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0912.1016
|
Refactoring of a Database
|
cs.DB
|
The technique of database refactoring is all about applying disciplined and
controlled techniques to change an existing database schema. The problem is to
successfully create a Database Refactoring Framework for databases. This paper
concentrates on the feasibility of adapting this concept to work as a generic
template. To retain the constraints regardless of the modifications to the
metadata, the paper proposes a MetaData Manipulation Tool to facilitate change.
The tool adopts a Template Design Pattern to make it database independent. The
paper presents a drawback of using java for constraint extraction and proposes
an alternative.
|
0912.1017
|
Genetic Programming Framework for Fingerprint Matching
|
cs.CR cs.CV cs.MM
|
A fingerprint matching is a very difficult problem. Minutiae based matching
is the most popular and widely used technique for fingerprint matching. The
minutiae points considered in automatic identification systems are based
normally on termination and bifurcation points. In this paper we propose a new
technique for fingerprint matching using minutiae points and genetic
programming. The goal of this paper is extracting the mathematical formula that
defines the minutiae points.
|
0912.1023
|
Efficient Relay Beamforming Design with SIC Detection for Dual-Hop MIMO
Relay Networks
|
cs.NI cs.IT math.IT
|
In this paper, we consider a dual-hop Multiple Input Multiple Output (MIMO)
relay wireless network, in which a source-destination pair both equipped with
multiple antennas communicates through a large number of half-duplex
amplify-and-forward (AF) relay terminals. Two novel linear beamforming schemes
based on the matched filter (MF) and regularized zero-forcing (RZF) precoding
techniques are proposed for the MIMO relay system. We focus on the linear
process at the relay nodes and design the new relay beamformers by utilizing
the channel state information (CSI) of both backward channel and forward
channel. The proposed beamforming designs are based on the QR decomposition
(QRD) filter at the destination node which performs successive interference
cancellation (SIC) to achieve the maximum spatial multiplexing gain. Simulation
results demonstrate that the proposed beamformers that fulfil both the
intranode array gain and distributed array gain outperform other relaying
schemes under different system parameters in terms of the ergodic capacity.
|
0912.1059
|
Reduced Complexity Angle-Doppler-Range Estimation for MIMO Radar That
Employs Compressive Sensing
|
cs.IT math.IT
|
The authors recently proposed a MIMO radar system that is implemented by a
small wireless network. By applying compressive sensing (CS) at the receive
nodes, the MIMO radar super-resolution can be achieved with far fewer
observations than conventional approaches. This previous work considered the
estimation of direction of arrival and Doppler. Since the targets are sparse in
the angle-velocity space, target information can be extracted by solving an l1
minimization problem. In this paper, the range information is exploited by
introducing step frequency to MIMO radar with CS. The proposed approach is able
to achieve high range resolution and also improve the ambiguous velocity.
However, joint angle-Doppler-range estimation requires discretization of the
angle-Doppler-range space which causes a sharp rise in the computational burden
of the l1 minimization problem. To maintain an acceptable complexity, a
technique is proposed to successively estimate angle, Doppler and range in a
decoupled fashion. The proposed approach can significantly reduce the
complexity without sacrificing performance.
|
0912.1110
|
XML Multidimensional Modelling and Querying
|
cs.DB
|
As XML becomes ubiquitous and XML storage and processing becomes more
efficient, the range of use cases for these technologies widens daily. One
promising area is the integration of XML and data warehouses, where an
XML-native database stores multidimensional data and processes OLAP queries
written in the XQuery interrogation language. This paper explores issues
arising in the implementation of such a data warehouse. We first compare
approaches for multidimensional data modelling in XML, then describe how
typical OLAP queries on these models can be expressed in XQuery. We then show
how, regardless of the model, the grouping features of XQuery 1.1 improve
performance and readability of these queries. Finally, we evaluate the
performance of query evaluation in each modelling choice using the eXist
database, which we extended with a grouping clause implementation.
|
0912.1128
|
How to Explain Individual Classification Decisions
|
stat.ML cs.LG
|
After building a classifier with modern tools of machine learning we
typically have a black box at hand that is able to predict well for unseen
data. Thus, we get an answer to the question what is the most likely label of a
given unseen data point. However, most methods will provide no answer why the
model predicted the particular label for a single instance and what features
were most influential for that particular instance. The only method that is
currently able to provide such explanations are decision trees. This paper
proposes a procedure which (based on a set of assumptions) allows to explain
the decisions of any classification method.
|
0912.1155
|
A Learning-Based Approach to Reactive Security
|
cs.CR cs.GT cs.LG
|
Despite the conventional wisdom that proactive security is superior to
reactive security, we show that reactive security can be competitive with
proactive security as long as the reactive defender learns from past attacks
instead of myopically overreacting to the last attack. Our game-theoretic model
follows common practice in the security literature by making worst-case
assumptions about the attacker: we grant the attacker complete knowledge of the
defender's strategy and do not require the attacker to act rationally. In this
model, we bound the competitive ratio between a reactive defense algorithm
(which is inspired by online learning theory) and the best fixed proactive
defense. Additionally, we show that, unlike proactive defenses, this reactive
strategy is robust to a lack of information about the attacker's incentives and
knowledge.
|
0912.1198
|
Delay-Optimal Power and Subcarrier Allocation for OFDMA Systems via
Stochastic Approximation
|
cs.LG
|
In this paper, we consider delay-optimal power and subcarrier allocation
design for OFDMA systems with $N_F$ subcarriers, $K$ mobiles and one base
station. There are $K$ queues at the base station for the downlink traffic to
the $K$ mobiles with heterogeneous packet arrivals and delay requirements. We
shall model the problem as a $K$-dimensional infinite horizon average reward
Markov Decision Problem (MDP) where the control actions are assumed to be a
function of the instantaneous Channel State Information (CSI) as well as the
joint Queue State Information (QSI). This problem is challenging because it
corresponds to a stochastic Network Utility Maximization (NUM) problem where
general solution is still unknown. We propose an {\em online stochastic value
iteration} solution using {\em stochastic approximation}. The proposed power
control algorithm, which is a function of both the CSI and the QSI, takes the
form of multi-level water-filling. We prove that under two mild conditions in
Theorem 1 (One is the stepsize condition. The other is the condition on
accessibility of the Markov Chain, which can be easily satisfied in most of the
cases we are interested.), the proposed solution converges to the optimal
solution almost surely (with probability 1) and the proposed framework offers a
possible solution to the general stochastic NUM problem. By exploiting the
birth-death structure of the queue dynamics, we obtain a reduced complexity
decomposed solution with linear $\mathcal{O}(KN_F)$ complexity and
$\mathcal{O}(K)$ memory requirement.
|
0912.1216
|
Distributive Subband Allocation, Power and Rate Control for
Relay-Assisted OFDMA Cellular System with Imperfect System State Knowledge
|
cs.NI cs.IT math.IT
|
In this paper, we consider distributive subband, power and rate allocation
for a two-hop transmission in an orthogonal frequency-division multiple-access
(OFDMA) cellular system with fixed relays which operate in decode-and-forward
strategy. We take into account of system fairness by considering weighted sum
goodput as our optimization objective. Based on the cluster-based architecture,
we obtain a fast-converging distributive solution with only local imperfect
CSIT by using decomposition of the optimization problem. To further reduce the
signaling overhead and computational complexity, we propose a reduced feedback
distributive solution, which can achieve asymptotically optimal performance for
large number of users with arbitrarily small feedback overhead per user. We
also derive asymptotic average system throughput for the relay-assisted OFDMA
system so as to obtain useful design insights.
|
0912.1224
|
The university-industry knowledge relationship: Analyzing patents and
the science base of technologies
|
cs.DL cs.CY cs.IR physics.soc-ph
|
Via the Internet, information scientists can obtain cost-free access to large
databases in the hidden or deep web. These databases are often structured far
more than the Internet domains themselves. The patent database of the U.S.
Patent and Trade Office is used in this study to examine the science base of
patents in terms of the literature references in these patents.
University-based patents at the global level are compared with results when
using the national economy of the Netherlands as a system of reference. Methods
for accessing the on-line databases and for the visualization of the results
are specified. The conclusion is that 'biotechnology' has historically
generated a model for theorizing about university-industry relations that
cannot easily be generalized to other sectors and disciplines.
|
0912.1294
|
Conception d'un outil d'aide \`a l'indexation de ressources
p\'edagogiques - Extraction automatique des th\'ematiques et des mots-clefs
de documents UNIT
|
cs.IR
|
Indexing learning documents using the Learning Object Metadata (LOM) is often
carried out manually by archivists. Filling out the LOM fields is a long and
difficult task, requiring a complete reading and a full knowledge on the topic
dealt within the document. In this paper, we present an innovative model and
method to assist the archivists in finding the important concepts and keywords
of a learning document. The application is performed using wikipedia's category
links.
|
0912.1310
|
Automatic creation of urban velocity fields from aerial video
|
cs.CV
|
In this paper, we present a system for modelling vehicle motion in an urban
scene from low frame-rate aerial video. In particular, the scene is modelled as
a probability distribution over velocities at every pixel in the image.
We describe the complete system for acquiring this model. The video is
captured from a helicopter and stabilized by warping the images to match an
orthorectified image of the area. A pixel classifier is applied to the
stabilized images, and the response is segmented to determine car locations and
orientations. The results are fed in to a tracking scheme which tracks cars for
three frames, creating tracklets. This allows the tracker to use a combination
of velocity, direction, appearance, and acceleration cues to keep only tracks
likely to be correct. Each tracklet provides a measurement of the car velocity
at every point along the tracklet's length, and these are then aggregated to
create a histogram of vehicle velocities at every pixel in the image.
The results demonstrate that the velocity probability distribution prior can
be used to infer a variety of information about road lane directions, speed
limits, vehicle speeds and common trajectories, and traffic bottlenecks, as
well as providing a means of describing environmental knowledge about traffic
rules that can be used in tracking.
|
0912.1333
|
Spectral Efficiency Optimization for an Interfering Cognitive Radio with
Adaptive Modulation and Coding
|
cs.IT math.IT
|
In this paper, we consider a primary and a cognitive user transmitting over a
wireless fading interference channel. The primary user transmits with a
constant power and utilizes an adaptive modulation and coding (AMC) scheme
satisfying a bit error rate requirement. We propose a link adaptation scheme to
maximize the average spectral efficiency of the cognitive radio, while a
minimum required spectral efficiency for the primary user is provisioned. The
resulting problem is constrained to also satisfy a bit error rate requirement
and a power constraint for the cognitive link. The AMC mode selection and power
control at the cognitive transmitter is optimized based on the modified signal
to noise plus interference ratio feedback of both links. The problem is then
cast as a nonlinear discrete optimization problem for which a fast and
efficient suboptimum solution is presented. We also present a scheme with rate
adaptive and constant power cognitive radio. An important characteristic of the
proposed schemes is that no computation or coordination overhead is imposed on
the primary radio due to the cognitive radio activity. Numerical results and
comparison with the interweave approach to cognitive radio demonstrate the
efficiency of the proposed solutions.
|
0912.1412
|
Topological Properties of an Exponential Random Geometric Graph Process
|
cs.IT cs.DM math.IT math.PR
|
In this paper, we consider a one-dimensional random geometric graph process
with the inter-nodal gaps evolving according to an exponential AR(1) process,
which may serve as a mobile wireless network model. The transition probability
matrix and stationary distribution are derived for the Markov chains in terms
of network connectivity and the number of components. We characterize an
algorithm for the hitting time regarding disconnectivity. In addition, we also
study topological properties for static snapshots. We obtain the degree
distributions as well as asymptotic precise bounds and strong law of large
numbers for connectivity threshold distance and the largest nearest neighbor
distance amongst others. Both closed form results and limit theorems are
provided.
|
0912.1420
|
Nonlinear Effects in Stiffness Modeling of Robotic Manipulators
|
cs.RO
|
The paper focuses on the enhanced stiffness modeling of robotic manipulators
by taking into account influence of the external force/torque acting upon the
end point. It implements the virtual joint technique that describes the
compliance of manipulator elements by a set of localized six-dimensional
springs separated by rigid links and perfect joints. In contrast to the
conventional formulation, which is valid for the unloaded mode and small
displacements, the proposed approach implicitly assumes that the loading leads
to the non-negligible changes of the manipulator posture and corresponding
amendment of the Jacobian. The developed numerical technique allows computing
the static equilibrium and relevant force/torque reaction of the manipulator
for any given displacement of the end-effector. This enables designer detecting
essentially nonlinear effects in elastic behavior of manipulator, similar to
the buckling of beam elements. It is also proposed the linearization procedure
that is based on the inversion of the dedicated matrix composed of the
stiffness parameters of the virtual springs and the Jacobians/Hessians of the
active and passive joints. The developed technique is illustrated by an
application example that deals with the stiffness analysis of a parallel
manipulator of the Orthoglide family.
|
0912.1421
|
Context and Keyword Extraction in Plain Text Using a Graph
Representation
|
cs.IR
|
Document indexation is an essential task achieved by archivists or automatic
indexing tools. To retrieve relevant documents to a query, keywords describing
this document have to be carefully chosen. Archivists have to find out the
right topic of a document before starting to extract the keywords. For an
archivist indexing specialized documents, experience plays an important role.
But indexing documents on different topics is much harder. This article
proposes an innovative method for an indexing support system. This system takes
as input an ontology and a plain text document and provides as output
contextualized keywords of the document. The method has been evaluated by
exploiting Wikipedia's category links as a termino-ontological resources.
|
0912.1440
|
Comment on "New Results on Frame-Proof Codes and Traceability Schemes"
|
cs.IT math.IT
|
In the paper "New Results on Frame-Proof Codes and Traceability Schemes" by
Reihaneh Safavi-Naini and Yejing Wang [IEEE Trans. Inform. Theory, vol. 47, no.
7, pp. 3029-3033, Nov. 2001], there are lower bounds for the maximal number of
codewords in binary frame-proof codes and decoders in traceability schemes.
There are also existence proofs using a construction of binary frame-proof
codes and traceability schemes. Here it is found that the main results in the
referenced paper do not hold.
|
0912.1534
|
Evolutionary multi-stage financial scenario tree generation
|
cs.NE q-fin.CP q-fin.PM
|
Multi-stage financial decision optimization under uncertainty depends on a
careful numerical approximation of the underlying stochastic process, which
describes the future returns of the selected assets or asset categories.
Various approaches towards an optimal generation of discrete-time,
discrete-state approximations (represented as scenario trees) have been
suggested in the literature. In this paper, a new evolutionary algorithm to
create scenario trees for multi-stage financial optimization models will be
presented. Numerical results and implementation details conclude the paper.
|
0912.1588
|
Self-organizing urban transportation systems
|
nlin.AO cs.MA
|
Urban transportation is a complex phenomenon. Since many agents are
constantly interacting in parallel, it is difficult to predict the future state
of a transportation system. Because of this, optimization techniques tend to
give obsolete solutions, as the problem changes before it can be optimized. An
alternative lies in seeking adaptive solutions. This adaptation can be achieved
with self-organization. In a self-organizing transportation system, the
elements of the system follow local rules to achieve a global solution. Like
this, when the problem changes the system can adapt by itself to the new
configuration.
In this chapter, I will review recent, current, and future work on
self-organizing transportation systems. Self-organizing traffic lights have
proven to improve traffic flow considerably over traditional methods. In public
transportation systems, simple rules are being explored to prevent the "equal
headway instability" phenomenon. The methods we have used can be also applied
to other urban transportation systems and their generality is discussed.
|
0912.1628
|
KF-CS: Compressive Sensing on Kalman Filtered Residual
|
cs.IT math.IT stat.ME
|
We consider the problem of recursively reconstructing time sequences of
sparse signals (with unknown and time-varying sparsity patterns) from a limited
number of linear incoherent measurements with additive noise. The idea of our
proposed solution, KF CS-residual (KF-CS) is to replace compressed sensing (CS)
on the observation by CS on the Kalman filtered (KF) observation residual
computed using the previous estimate of the support. KF-CS error stability over
time is studied. Simulation comparisons with CS and LS-CS are shown.
|
0912.1655
|
Maximum-likelihood co-channel interference cancellation with power
control for cellular OFDM networks
|
cs.IT math.IT
|
In cellular Orthogonal Frequency Division Multiplexing (OFDM) networks,
Co-Channel Interference (CCI) leads to severe degradation in the BER
performance. To solve this problem, Maximum-Likelihood Estimation (MLE) CCI
cancellation scheme has been proposed in the literature. MLE CCI cancellation
scheme generates weighted replicas of the transmitted signals and selects
replica with the smallest Euclidean distance from the received signal. When the
received power of the desired and interference signals are nearly the same, the
BER performance is degraded. In this paper, we propose an improved MLE CCI
canceler with closed-loop Power Control (PC) scheme capable of detecting and
combating against the equal received power situation at the Mobile Station (MS)
receiver by using the newly introduced parameter Power Ratio (PR). At cell edge
where Signal to Interferer Ratio (SIR) is considered to have average value
between -5 and 10 dB, computer simulations show that the proposed closed-loop
PC scheme has a gain of 7 dB at 28 km/h and about 2 dB at 120 km/h.
|
0912.1658
|
On the achievable improvement by the linear minimum mean square error
detector
|
cs.IT math.IT
|
Linear minimum mean square error (MMSE) detector has been shown to alleviate
the noise amplification problem, resulting in the conventional zero-forcing
(ZF) detector. In this paper, we analyze the performance improvement by the
MMSE detector in terms of the condition number of its filtering matrix, and in
terms of the post-precessing signal to noise ratio (SNR) improvement. To this
end, we derive explicit formulas for the condition numbers of the filtering
matrices and the post-processing SNRs. Analytical and simulation results
demonstrate that the improvement achieved by the MMSE detector over the ZF
detector is not only dependent on the noise variance and the condition number
of the channel matrix, but also on how close the smallest singular values are
to the noise variance.
|
0912.1661
|
Fixed-complexity vector perturbation with Block diagonalization for
MU-MIMO systems
|
cs.IT math.IT
|
Block diagonalization (BD) is an attractive technique that transforms the
multi-user multiple-input multiple-output (MU-MIMO) channel into parallel
single-user MIMO (SU-MIMO) channels with zero inter-user interference (IUI). In
this paper, we combine the BD technique with two deterministic vector
perturbation (VP) algorithms that reduce the transmit power in MU-MIMO systems
with linear precoding. These techniques are the fixed-complexity sphere encoder
(FSE) and the QR-decomposition with M-algorithm encoder (QRDM-E). In contrast
to the conventional BD VP technique, which is based on the sphere encoder (SE),
the proposed techniques have fixed complexity and a tradeoff between
performance and complexity can be achieved by controlling the size of the set
of candidates for the perturbation vector. Simulation results and analysis
demonstrate the properness of the proposed techniques for the next generation
mobile communications systems which are latency and computational complexity
limited. In MU-MIMO system with 4 users each equipped with 2 receive antennas,
simulation results show that the proposed BD-FSE and BD-QRDM-E outperforms the
conventional BD-THP (Tomlinson Harashima precoding) by 5.5 and 7.4dB,
respectively, at a target BER of 10^{-4}.
|
0912.1767
|
An evaluation of Flickrs distributed classification system, from the
perspective of its members, and as an image retrieval tool in comparison with
a controlled vocabulary
|
cs.DL cs.IT math.IT
|
The profusion of online digital images presents new challenges for image
indexing. Images have always been problematic to describe and catalogue due to
lack of inherent textual data and ambiguity of meaning. An alternative to
time-consuming professionally-applied metadata has been sought in the form of
tags, simple keywords that form a flat structure known as distributed
classification, or more popularly as a folksonomy.
This research aims to increase understanding of why people tag and how
effective they find it for searching, using as the focus. Open-ended
questionnaires were sent out to members of the photo-sharing website Flickr,
with the opportunity to post comments to an online discussion space. There is
also a systematic comparison between a tag-based system and a more traditional
controlled vocabulary, to test out the claims made regarding the suitability of
tagging for searching and browsing. For this purpose Flickr has been compared
with Getty Images using a series of test themes.
The small number of people who replied to the questionnaire gave detailed
answers that confirmed several assertions made about tags: they are accepted
despite their flaws (sloppiness and potential for inaccuracy) because they
serve their purpose to a satisfactory level. Some answers challenged the
assumption that tagging is only done for personal benefit. The search
comparison found that while Getty allows highly specific queries and logical
semantic links, Flickr is more flexible and better placed to deal with subtle
concepts. The overall conclusion is that tags achieve most when used in
conjunction with groupings of people with a shared interest.
|
0912.1768
|
Frequency of Occurrence and Information Entropy of American Sign
Language
|
cs.IT math.IT
|
American Sign Language (ASL) uses a series of hand based gestures as a
replacement for words to allow the deaf to communicate. Previous work has shown
that although it takes longer to make signs than to say the equivalent words,
on average sentences can be completed in about the same time. This leaves
unresolved, however, precisely why that should be the case. This paper reports
a determination of the empirical entropy and redundancy in the set of
handshapes of ASL. In this context, the entropy refers to the average
information content in a unit of data. It is found that the handshapes, as
fundamental units of ASL, are less redundant than phonemes, the equivalent
fundamental units of spoken English, and that their entropy is much closer to
the maximum possible information content. This explains why the slower signs
can produce sentences in the same time as speaking; the low redundancy
compensates for the slow rate of sign production. In addition to this precise
quantification, this work is also novel in its approach towards quantifying an
aspect of the ASL alphabet. Unlike spoken and written languages, frequency
analysis of ASL is difficult due to the fact that every sign is composed of
phonemes that are created through a combination of manual and a relatively
large and imprecise set of bodily features. Focusing on handshapes as the
ubiquitous and universal feature of all sign languages permits a precise
quantitative analysis. As interest in visual electronic communication explodes
within the deaf community, this work also paves the way for more precise
automated sign recognition and synthesis.
|
0912.1790
|
A Note on the Injection Distance
|
cs.IT math.IT
|
Koetter and Kschischang showed in [R. Koetter and F.R. Kschischang, "Coding
for Errors and Erasures in Random Network Coding," IEEE Trans. Inform. Theory,
{54(8), 2008] that the network coding counterpart of Gabidulin codes performs
asymptotically optimal with respect to the subspace distance. Recently, Silva
and Kschischang introduced in [D. Silva and F.R. Kschischang, "On Metrics for
Error Correction in Network Coding," To appear in IEEE Trans. Inform. Theory,
ArXiv: 0805.3824v4[cs.IT], 2009] the injection distance to give a detailed
picture of what happens in noncoherent network coding. We show that the above
codes are also asymptotically optimal with respect to this distance.
|
0912.1815
|
Detection of Denial of Service Attacks against Domain Name System Using
Neural Networks
|
cs.CR cs.NE
|
In this paper we introduce an intrusion detection system for Denial of
Service (DoS) attacks against Domain Name System (DNS). Our system architecture
consists of two most important parts: a statistical preprocessor and a neural
network classifier. The preprocessor extracts required statistical features in
a shorttime frame from traffic received by the target name server. We compared
three different neural networks for detecting and classifying different types
of DoS attacks. The proposed system is evaluated in a simulated network and
showed that the best performed neural network is a feed-forward backpropagation
with an accuracy of 99%.
|
0912.1820
|
Parsing of part-of-speech tagged Assamese Texts
|
cs.CL
|
A natural language (or ordinary language) is a language that is spoken,
written, or signed by humans for general-purpose communication, as
distinguished from formal languages (such as computer-programming languages or
the "languages" used in the study of formal logic). The computational
activities required for enabling a computer to carry out information processing
using natural language is called natural language processing. We have taken
Assamese language to check the grammars of the input sentence. Our aim is to
produce a technique to check the grammatical structures of the sentences in
Assamese text. We have made grammar rules by analyzing the structures of
Assamese sentences. Our parsing program finds the grammatical errors, if any,
in the Assamese sentence. If there is no error, the program will generate the
parse tree for the Assamese sentence
|
0912.1822
|
Association Rule Pruning based on Interestingness Measures with
Clustering
|
cs.LG
|
Association rule mining plays vital part in knowledge mining. The difficult
task is discovering knowledge or useful rules from the large number of rules
generated for reduced support. For pruning or grouping rules, several
techniques are used such as rule structure cover methods, informative cover
methods, rule clustering, etc. Another way of selecting association rules is
based on interestingness measures such as support, confidence, correlation, and
so on. In this paper, we study how rule clusters of the pattern Xi - Y are
distributed over different interestingness measures.
|
0912.1826
|
Robust Video Watermarking using Multi-Band Wavelet Transform
|
cs.IT math.IT
|
This paper addresses copyright protection as a major security demand in
digital marketplaces. Two watermarking techniques are proposed and compared for
compressed and uncompressed video with the intention to show the advantages and
the possible weaknesses in the schemes working in the frequency domain and in
the spatial domain. In this paper a robust video watermarking method is
presented. This method embeds data to the specific bands in the wavelet domain
using motion estimation approach. The algorithm uses the HL and LH bands to add
the watermark where the motion in these bands does not affect the quality of
extracted watermark if the video is subjected to different types of malicious
attacks. Watermark is embedded in an additive way using random Gaussian
distribution in video sequences. The method is tested on different types of
video (compressed DVD quality movie and uncompressed digital camera movie). The
proposed watermarking method in frequency domain has strong robustness against
some attacks such as frame dropping, frame filtering and lossy compression. The
experimental results indicate that the similarity measure before and after
certain attacks is very close to each other in frequency domain in comparison
to the spatial domain.
|
0912.1828
|
Using social annotation and web log to enhance search engine
|
cs.IR cs.CY
|
Search services have been developed rapidly in social Internet. It can help
web users easily to find their documents. So that, finding a best method search
is always an imagine. This paper would like introduce hybrid method of
LPageRank algorithm and Social Sim Rank algorithm. LPageRank is the method
using link structure to rank priority of page. It doesn't care content of page
and content of query. Therefore, we want to use benefit of social annotations
to create the latent semantic association between queries and annotations. This
model, we use algorithm SocialPageRank and LPageRank to enhance accuracy of
search system. To experiment and evaluate the proposed of the new model, we
have used this model for Music Machine Website with their web logs.
|
0912.1829
|
Document Searching System based on Natural Language Query Processing for
Vietnam Open Courseware Library
|
cs.IR cs.CL
|
The necessary of buiding the searching system being able to support users
expressing their searching by natural language queries is very important and
opens the researching direction with many potential. It combines the
traditional methods of information retrieval and the researching of Question
Answering (QA). In this paper, we introduce a searching system built by us for
searching courses on the Vietnam OpenCourseWare Program (VOCW). It can be
considered as the first tool to be able to perform the user's Vietnamese
questions. The experiment results are rather good when we evaluate this system
on the precision
|
0912.1830
|
Gesture Recognition with a Focus on Important Actions by Using a Path
Searching Method in Weighted Graph
|
cs.CV cs.LG
|
This paper proposes a method of gesture recognition with a focus on important
actions for distinguishing similar gestures. The method generates a partial
action sequence by using optical flow images, expresses the sequence in the
eigenspace, and checks the feature vector sequence by applying an optimum
path-searching method of weighted graph to focus the important actions. Also
presented are the results of an experiment on the recognition of similar sign
language words.
|
0912.1883
|
The Bellman equation for power utility maximization with semimartingales
|
q-fin.PM cs.SY math.OC math.PR q-fin.CP
|
We study utility maximization for power utility random fields with and
without intermediate consumption in a general semimartingale model with closed
portfolio constraints. We show that any optimal strategy leads to a solution of
the corresponding Bellman equation. The optimal strategies are described
pointwise in terms of the opportunity process, which is characterized as the
minimal solution of the Bellman equation. We also give verification theorems
for this equation.
|
0912.1909
|
MIMO Precoding with X- and Y-Codes
|
cs.IT math.IT
|
We consider a time division duplex (TDD) $n_t \times n_r$ multiple-input
multiple-output (MIMO) system with channel state information (CSI) at both the
transmitter and receiver. We propose X- and Y-Codes to achieve high
multiplexing and diversity gains at low complexity. The proposed precoding
schemes are based upon the singular value decomposition (SVD) of the channel
matrix which transforms the MIMO channel into parallel subchannels. Then X- and
Y-Codes are used to improve the diversity gain by pairing the subchannels,
prior to SVD precoding. In particular, the subchannels with good diversity are
paired with those having low diversity gains. Hence, a pair of channels is
jointly encoded using a $2 \times 2$ real matrix, which is fixed {\em a priori}
and does not change with each channel realization. For X-Codes these matrices
are 2-dimensional rotation matrices parameterized by a single angle, while for
Y-Codes, these matrices are 2-dimensional upper left triangular matrices. The
complexity of the maximum likelihood decoding (MLD) for both X- and Y-Codes is
low. Specifically, the decoding complexity of Y-Codes is the same as that of a
scalar channel. Moreover, we propose X-, Y-Precoders with the same structure as
X-, Y-Codes, but the encoding matrices adapt to each channel realization. The
optimal encoding matrices for X-, Y-Codes/Precoders are derived analytically.
Finally, it is observed that X-Codes/Precoders perform better for
well-conditioned channels, while Y-Codes/Precoders perform better for
ill-conditioned channels, when compared to other precoding schemes in the
literature.
|
0912.1987
|
Training and Feedback Optimization for Multiuser MIMO Downlink
|
cs.IT math.IT
|
We consider a MIMO fading broadcast channel where the fading channel
coefficients are constant over time-frequency blocks that span a coherent time
$\times$ a coherence bandwidth. In closed-loop systems, channel state
information at transmitter (CSIT) is acquired by the downlink training sent by
the base station and an explicit feedback from each user terminal. In open-loop
systems, CSIT is obtained by exploiting uplink training and channel
reciprocity. We use a tight closed-form lower bound on the ergodic achievable
rate in the presence of CSIT errors in order to optimize the overall system
throughput, by taking explicitly into account the overhead due to channel
estimation and channel state feedback. Based on three time-frequency block
models inspired by actual systems, we provide some useful guidelines for the
overall system optimization. In particular, digital (quantized) feedback is
found to offer a substantial advantage over analog (unquantized) feedback.
|
0912.2134
|
Enterprise Multi-Branch Database Synchronization with MSMQ
|
cs.DB cs.NI
|
When we talk about databases there have always been problems concerning data
synchronization. The latter is a technique for maintaining consistency among
different copies of data (often called replicas). In general, there is no
universal solution to this problem and often a particular situation requires a
particular approach driven by specific conditions. This paper presents an
approach tackling the issue of data synchronization in a distributed
multi-branch enterprise database. The proposed solution is based on MSMQ
(Microsoft Message Queue), a mechanism for asynchronous messaging.
|
0912.2282
|
Design of Intelligent layer for flexible querying in databases
|
cs.DB cs.AI
|
Computer-based information technologies have been extensively used to help
many organizations, private companies, and academic and education institutions
manage their processes and information systems hereby become their nervous
centre. The explosion of massive data sets created by businesses, science and
governments necessitates intelligent and more powerful computing paradigms so
that users can benefit from this data. Therefore most new-generation database
applications demand intelligent information management to enhance efficient
interactions between database and the users. Database systems support only a
Boolean query model. A selection query on SQL database returns all those tuples
that satisfy the conditions in the query.
|
0912.2302
|
Synthesis of supervised classification algorithm using intelligent and
statistical tools
|
cs.CV cs.LG
|
A fundamental task in detecting foreground objects in both static and dynamic
scenes is to take the best choice of color system representation and the
efficient technique for background modeling. We propose in this paper a
non-parametric algorithm dedicated to segment and to detect objects in color
images issued from a football sports meeting. Indeed segmentation by pixel
concern many applications and revealed how the method is robust to detect
objects, even in presence of strong shadows and highlights. In the other hand
to refine their playing strategy such as in football, handball, volley ball,
Rugby..., the coach need to have a maximum of technical-tactics information
about the on-going of the game and the players. We propose in this paper a
range of algorithms allowing the resolution of many problems appearing in the
automated process of team identification, where each player is affected to his
corresponding team relying on visual data. The developed system was tested on a
match of the Tunisian national competition. This work is prominent for many
next computer vision studies as it's detailed in this study.
|
0912.2307
|
Rank Based Clustering For Document Retrieval From Biomedical Databases
|
cs.IR cs.DB
|
Now a day's, search engines are been most widely used for extracting
information's from various resources throughout the world. Where, majority of
searches lies in the field of biomedical for retrieving related documents from
various biomedical databases. Currently search engines lacks in document
clustering and representing relativeness level of documents extracted from the
databases. In order to overcome these pitfalls a text based search engine have
been developed for retrieving documents from Medline and PubMed biomedical
databases. The search engine has incorporated page ranking bases clustering
concept which automatically represents relativeness on clustering bases. Apart
from this graph tree construction is made for representing the level of
relatedness of the documents that are networked together. This advance
functionality incorporation for biomedical document based search engine found
to provide better results in reviewing related documents based on relativeness.
|
0912.2310
|
NeuralNetwork Based 3D Surface Reconstruction
|
cs.NE
|
This paper proposes a novel neural-network-based adaptive hybrid-reflectance
three-dimensional (3-D) surface reconstruction model. The neural network
combines the diffuse and specular components into a hybrid model. The proposed
model considers the characteristics of each point and the variant albedo to
prevent the reconstructed surface from being distorted. The neural network
inputs are the pixel values of the two-dimensional images to be reconstructed.
The normal vectors of the surface can then be obtained from the output of the
neural network after supervised learning, where the illuminant direction does
not have to be known in advance. Finally, the obtained normal vectors can be
applied to integration method when reconstructing 3-D objects. Facial images
were used for training in the proposed approach
|
0912.2311
|
VirusPKT: A Search Tool For Assimilating Assorted Acquaintance For
Viruses
|
cs.IR q-bio.OT
|
Viruses utilize various means to circumvent the immune detection in the
biological systems. Several mathematical models have been investigated for the
description of viral dynamics in the biological system of human and various
other species. One common strategy for evasion and recognition of viruses is,
through acquaintance in the systems by means of search engines. In this
perspective a search tool have been developed to provide a wider comprehension
about the structure and other details on viruses which have been narrated in
this paper. This provides an adequate knowledge in evolution and building of
viruses, its functions through information extraction from various websites.
Apart from this, tool aim to automate the activities associated with it in a
self-maintainable, self-sustainable, proactive one which has been evaluated
through analysis made and have been discussed in this paper.
|
0912.2314
|
Early Detection of Breast Cancer using SVM Classifier Technique
|
cs.LG
|
This paper presents a tumor detection algorithm from mammogram. The proposed
system focuses on the solution of two problems. One is how to detect tumors as
suspicious regions with a very weak contrast to their background and another is
how to extract features which categorize tumors. The tumor detection method
follows the scheme of (a) mammogram enhancement. (b) The segmentation of the
tumor area. (c) The extraction of features from the segmented tumor area. (d)
The use of SVM classifier. The enhancement can be defined as conversion of the
image quality to a better and more understandable level. The mammogram
enhancement procedure includes filtering, top hat operation, DWT. Then the
contrast stretching is used to increase the contrast of the image. The
segmentation of mammogram images has been playing an important role to improve
the detection and diagnosis of breast cancer. The most common segmentation
method used is thresholding. The features are extracted from the segmented
breast area. Next stage include, which classifies the regions using the SVM
classifier. The method was tested on 75 mammographic images, from the mini-MIAS
database. The methodology achieved a sensitivity of 88.75%.
|
0912.2316
|
Heart Rate Variability Analysis Using Threshold of Wavelet Package
Coefficients
|
cs.CV physics.data-an physics.med-ph
|
In this paper, a new efficient feature extraction method based on the
adaptive threshold of wavelet package coefficients is presented. This paper
especially deals with the assessment of autonomic nervous system using the
background variation of the signal Heart Rate Variability HRV extracted from
the wavelet package coefficients. The application of a wavelet package
transform allows us to obtain a time-frequency representation of the signal,
which provides better insight in the frequency distribution of the signal with
time. A 6 level decomposition of HRV was achieved with db4 as mother wavelet,
and the above two bands LF and HF were combined in 12 specialized frequencies
sub-bands obtained in wavelet package transform. Features extracted from these
coefficients can efficiently represent the characteristics of the original
signal. ANOVA statistical test is used for the evaluation of proposed
algorithm.
|
0912.2378
|
Limited Feedback for Temporally Correlated MIMO Channels with Other Cell
Interference
|
cs.IT math.IT
|
Limited feedback improves link reliability with a small amount of feedback
from the receiver back to the transmitter. In cellular systems, the performance
of limited feedback will be degraded in the presence of other cell
interference, when the base stations have limited or no coordination. This
paper establishes the degradation in sum rate of users in a cellular system,
due to uncoordinated other cell interference and delay on the feedback channel.
A goodput metric is defined as the rate when the bits are successfully received
at the mobile station, and used to derive an upper bound on the performance of
limited feedback systems with delay. This paper shows that the goodput gained
from having delayed limited feedback decreases doubly exponentially as the
delay increases. The analysis is extended to precoded spatial multiplexing
systems where it is shown that the same upper bound can be used to evaluate the
decay in the achievable sum rate. To reduce the effects of interference, zero
forcing interference cancellation is applied at the receiver, where it is shown
that the effect of the interference on the achievable sum rate can be
suppressed by nulling out the interferer. Numerical results show that the decay
rate of the goodput decreases when the codebook quantization size increases and
when the doppler shift in the channel decreases.
|
0912.2381
|
LAGOVirtual: A Collaborative Environment for the Large Aperture GRB
Observatory
|
cs.CE astro-ph.HE astro-ph.IM hep-ex
|
We present the LAGOVirtual Project: an ongoing project to develop platform to
collaborate in the Large Aperture GRB Observatory (LAGO). This continental-wide
observatory is devised to detect high energy (around 100 GeV) component of
Gamma Ray Bursts, by using the single particle technique in arrays of Water
Cherenkov Detectors (WCD) at high mountain sites (Chacaltaya, Bolivia, 5300 m
a.s.l., Pico Espejo, Venezuela, 4750 m a.s.l., Sierra Negra, Mexico, 4650 m
a.s.l). This platform will allow LAGO collaboration to share data, and computer
resources through its different sites. This environment has the possibility to
generate synthetic data by simulating the showers through AIRES application and
to store/preserve distributed data files collected by the WCD at the LAGO
sites. The present article concerns the implementation of a prototype of
LAGO-DR adapting DSpace, with a hierarchical structure (i.e. country,
institution, followed by collections that contain the metadata and data files),
for the captured/simulated data. This structure was generated by using the
community, sub-community, collection, item model; available at the DSpace
software. Each member institution-country of the project has the appropriate
permissions on the system to publish information (descriptive metadata and
associated data files). The platform can also associate multiple files to each
item of data (data from the instruments, graphics, postprocessed-data, etc.).
|
0912.2385
|
Closing the Learning-Planning Loop with Predictive State Representations
|
cs.LG cs.AI
|
A central problem in artificial intelligence is that of planning to maximize
future reward under uncertainty in a partially observable environment. In this
paper we propose and demonstrate a novel algorithm which accurately learns a
model of such an environment directly from sequences of action-observation
pairs. We then close the loop from observations to actions by planning in the
learned model and recovering a policy which is near-optimal in the original
environment. Specifically, we present an efficient and statistically consistent
spectral algorithm for learning the parameters of a Predictive State
Representation (PSR). We demonstrate the algorithm by learning a model of a
simulated high-dimensional, vision-based mobile robot planning task, and then
perform approximate point-based planning in the learned PSR. Analysis of our
results shows that the algorithm learns a state space which efficiently
captures the essential features of the environment. This representation allows
accurate prediction with a small number of parameters, and enables successful
and efficient planning.
|
0912.2404
|
Succinct Coverage Oracles
|
cs.DS cs.DB
|
In this paper, we identify a fundamental algorithmic problem that we term
succinct dynamic covering (SDC), arising in many modern-day web applications,
including ad-serving and online recommendation systems in eBay and Netflix.
Roughly speaking, SDC applies two restrictions to the well-studied Max-Coverage
problem: Given an integer k, X={1,2,...,n} and I={S_1, ..., S_m}, S_i a subset
of X, find a subset J of I, such that |J| <= k and the union of S in J is as
large as possible. The two restrictions applied by SDC are: (1) Dynamic: At
query-time, we are given a query Q, a subset of X, and our goal is to find J
such that the intersection of Q with the union of S in J is as large as
possible; (2) Space-constrained: We don't have enough space to store (and
process) the entire input; specifically, we have o(mn), and maybe as little as
O((m+n)polylog(mn)) space. The goal of SDC is to maintain a small data
structure so as to answer most dynamic queries with high accuracy. We call such
a scheme a Coverage Oracle.
We present algorithms and complexity results for coverage oracles. We present
deterministic and probabilistic near-tight upper and lower bounds on the
approximation ratio of SDC as a function of the amount of space available to
the oracle. Our lower bound results show that to obtain constant-factor
approximations we need Omega(mn) space. Fortunately, our upper bounds present
an explicit tradeoff between space and approximation ratio, allowing us to
determine the amount of space needed to guarantee certain accuracy.
|
0912.2415
|
Adapting Heuristic Mastermind Strategies to Evolutionary Algorithms
|
cs.NE cs.AI
|
The art of solving the Mastermind puzzle was initiated by Donald Knuth and is
already more than 30 years old; despite that, it still receives much attention
in operational research and computer games journals, not to mention the
nature-inspired stochastic algorithm literature. In this paper we try to
suggest a strategy that will allow nature-inspired algorithms to obtain results
as good as those based on exhaustive search strategies; in order to do that, we
first review, compare and improve current approaches to solving the puzzle;
then we test one of these strategies with an estimation of distribution
algorithm. Finally, we try to find a strategy that falls short of being
exhaustive, and is then amenable for inclusion in nature inspired algorithms
(such as evolutionary or particle swarm algorithms). This paper proves that by
the incorporation of local entropy into the fitness function of the
evolutionary algorithm it becomes a better player than a random one, and gives
a rule of thumb on how to incorporate the best heuristic strategies to
evolutionary algorithms without incurring in an excessive computational cost.
|
0912.2425
|
Consensus and synchronization in discrete-time networks of multi-agents
with stochastically switching topologies and time delays
|
math.DS cs.SY math.OC
|
We analyze stability of consensus algorithms in networks of multi-agents with
time-varying topologies and delays. The topology and delays are modeled as
induced by an adapted process and are rather general, including i.i.d.\
topology processes, asynchronous consensus algorithms, and Markovian jumping
switching. In case the self-links are instantaneous, we prove that the network
reaches consensus for all bounded delays if the graph corresponding to the
conditional expectation of the coupling matrix sum across a finite time
interval has a spanning tree almost surely. Moreover, when self-links are also
delayed and when the delays satisfy certain integer patterns, we observe and
prove that the algorithm may not reach consensus but instead synchronize at a
periodic trajectory, whose period depends on the delay pattern. We also give a
brief discussion on the dynamics in the absence of self-links.
|
0912.2492
|
Learning an Interactive Segmentation System
|
stat.ML cs.CV stat.ME
|
Many successful applications of computer vision to image or video
manipulation are interactive by nature. However, parameters of such systems are
often trained neglecting the user. Traditionally, interactive systems have been
treated in the same manner as their fully automatic counterparts. Their
performance is evaluated by computing the accuracy of their solutions under
some fixed set of user interactions. This paper proposes a new evaluation and
learning method which brings the user in the loop. It is based on the use of an
active robot user - a simulated model of a human user. We show how this
approach can be used to evaluate and learn parameters of state-of-the-art
interactive segmentation systems. We also show how simulated user models can be
integrated into the popular max-margin method for parameter learning and
propose an algorithm to solve the resulting optimisation problem.
|
0912.2548
|
Towards Utility-driven Anonymization of Transactions
|
cs.DB cs.CR
|
Publishing person-specific transactions in an anonymous form is increasingly
required by organizations. Recent approaches ensure that potentially
identifying information (e.g., a set of diagnosis codes) cannot be used to link
published transactions to persons' identities, but all are limited in
application because they incorporate coarse privacy requirements (e.g.,
protecting a certain set of m diagnosis codes requires protecting all m-sized
sets), do not integrate utility requirements, and tend to explore a small
portion of the solution space. In this paper, we propose a more general
framework for anonymizing transactional data under specific privacy and utility
requirements. We model such requirements as constraints, investigate how these
constraints can be specified, and propose COAT (COnstraint-based Anonymization
of Transactions), an algorithm that anonymizes transactions using a flexible
hierarchy-free generalization scheme to meet the specified constraints.
Experiments with benchmark datasets verify that COAT significantly outperforms
the current state-of-the-art algorithm in terms of data utility, while being
comparable in terms of efficiency. The effectiveness of our approach is also
demonstrated in a real-world scenario, which requires disseminating a private,
patient-specific transactional dataset in a way that preserves both privacy and
utility in intended studies.
|
0912.2551
|
Efficient Parallel Statistical Model Checking of Biochemical Networks
|
cs.CE cs.DC cs.LO q-bio.QM
|
We consider the problem of verifying stochastic models of biochemical
networks against behavioral properties expressed in temporal logic terms. Exact
probabilistic verification approaches such as, for example, CSL/PCTL model
checking, are undermined by a huge computational demand which rule them out for
most real case studies. Less demanding approaches, such as statistical model
checking, estimate the likelihood that a property is satisfied by sampling
executions out of the stochastic model. We propose a methodology for
efficiently estimating the likelihood that a LTL property P holds of a
stochastic model of a biochemical network. As with other statistical
verification techniques, the methodology we propose uses a stochastic
simulation algorithm for generating execution samples, however there are three
key aspects that improve the efficiency: first, the sample generation is driven
by on-the-fly verification of P which results in optimal overall simulation
time. Second, the confidence interval estimation for the probability of P to
hold is based on an efficient variant of the Wilson method which ensures a
faster convergence. Third, the whole methodology is designed according to a
parallel fashion and a prototype software tool has been implemented that
performs the sampling/verification process in parallel over an HPC
architecture.
|
0912.2563
|
A Model-Based Approach to Predicting Predator-Prey & Friend-Foe
Relationships in Ant Colonies
|
cs.AI cs.CV q-bio.PE
|
Understanding predator-prey relationships among insects is a challenging task
in the domain of insect-colony research. This is due to several factors
involved, such as determining whether a particular behavior is the result of a
predator-prey interaction, a friend-foe interaction or another kind of
interaction. In this paper, we analyze a series of predator-prey and friend-foe
interactions in two colonies of carpenter ants to better understand and predict
such behavior. Using the data gathered, we have also come up with a preliminary
model for predicting such behavior under the specific conditions the experiment
was conducted in. In this paper, we present the results of our data analysis as
well as an overview of the processes involved.
|
0912.2630
|
Transmission Capacity of Ad-hoc Networks with Multiple Antennas using
Transmit Stream Adaptation and Interference Cancelation
|
cs.IT math.IT
|
The transmission capacity of an ad-hoc network is the maximum density of
active transmitters per unit area, given an outage constraint at each receiver
for a fixed rate of transmission. Assuming that the transmitter locations are
distributed as a Poisson point process, this paper derives upper and lower
bounds on the transmission capacity of an ad-hoc network when each node is
equipped with multiple antennas. The transmitter either uses eigen multi-mode
beamforming or a subset of its antennas to transmit multiple data streams,
while the receiver uses partial zero forcing to cancel certain interferers
using some of its spatial receive degrees of freedom (SRDOF). The receiver
either cancels the nearest interferers or those interferers that maximize the
post-cancelation signal-to-interference ratio. Using the obtained bounds, the
optimal number of data streams to transmit, and the optimal SRDOF to use for
interference cancelation are derived that provide the best scaling of the
transmission capacity with the number of antennas. With beamforming, single
data stream transmission together with using all but one SRDOF for interference
cancelation is optimal, while without beamforming, single data stream
transmission together with using a fraction of the total SRDOF for interference
cancelation is optimal.
|
0912.2709
|
The Gaussian Surface Area and Noise Sensitivity of Degree-$d$
Polynomials
|
cs.CC cs.LG
|
We provide asymptotically sharp bounds for the Gaussian surface area and the
Gaussian noise sensitivity of polynomial threshold functions. In particular we
show that if $f$ is a degree-$d$ polynomial threshold function, then its
Gaussian sensitivity at noise rate $\epsilon$ is less than some quantity
asymptotic to $\frac{d\sqrt{2\epsilon}}{\pi}$ and the Gaussian surface area is
at most $\frac{d}{\sqrt{2\pi}}$. Furthermore these bounds are asymptotically
tight as $\epsilon\to 0$ and $f$ the threshold function of a product of $d$
distinct homogeneous linear functions.
|
0912.2737
|
An Extreme form of Superactivation for Quantum Zero-Error Capacities
|
quant-ph cs.IT math.IT
|
The zero-error capacity of a channel is the rate at which it can send
information perfectly, with zero probability of error, and has long been
studied in classical information theory. We show that the zero-error capacity
of quantum channels exhibits an extreme form of non-additivity, one which is
not possible for classical channels, or even for the usual capacities of
quantum channels. By combining probabilistic arguments with algebraic geometry,
we prove that there exist channels E1 and E2 with no zero-error classical
capacity whatsoever, C_0(E1) = C_0(E2) = 0, but whose joint zero-error quantum
capacity is positive, Q_0(E1 x E2) >= 1. This striking effect is an extreme
from of the superactivation phenomenon, as it implies that both the classical
and quantum zero-error capacities of these channels can be superactivated
simultaneously, whilst being a strictly stronger property of capacities.
Superactivation of the quantum zero-error capacity was not previously known.
|
0912.2820
|
Network Coding for Computing: Cut-Set Bounds
|
cs.IT math.IT
|
The following \textit{network computing} problem is considered. Source nodes
in a directed acyclic network generate independent messages and a single
receiver node computes a target function $f$ of the messages. The objective is
to maximize the average number of times $f$ can be computed per network usage,
i.e., the ``computing capacity''. The \textit{network coding} problem for a
single-receiver network is a special case of the network computing problem in
which all of the source messages must be reproduced at the receiver. For
network coding with a single receiver, routing is known to achieve the capacity
by achieving the network \textit{min-cut} upper bound. We extend the definition
of min-cut to the network computing problem and show that the min-cut is still
an upper bound on the maximum achievable rate and is tight for computing (using
coding) any target function in multi-edge tree networks and for computing
linear target functions in any network. We also study the bound's tightness for
different classes of target functions. In particular, we give a lower bound on
the computing capacity in terms of the Steiner tree packing number and a
different bound for symmetric functions. We also show that for certain networks
and target functions, the computing capacity can be less than an arbitrarily
small fraction of the min-cut bound.
|
0912.2822
|
Data management in Systems biology II - Outlook towards the semantic web
|
cs.DB q-bio.OT
|
The benefit of using ontologies, defined by the respective data standards, is
shown. It is presented how ontologies can be used for the semantic enrichment
of data and how this can contribute to the vision of the semantic web to become
true. The problems existing today on the way to a true semantic web are
pinpointed, different semantic web standards, tools and development frameworks
are overlooked and an outlook towards artificial intelligence and agents for
searching and mining the data in the semantic web are given, paving the way
from data management to information and in the end true knowledge management
systems.
|
0912.2826
|
An iterative approach for generating statistically realistic populations
of households
|
cs.MA cs.CY
|
Background: Many different simulation frameworks, in different topics, need
to treat realistic datasets to initialize and calibrate the system. A precise
reproduction of initial states is extremely important to obtain reliable
forecast from the model. Methodology/Principal Findings: This paper proposes an
algorithm to create an artificial population where individuals are described by
their age, and are gathered in households respecting a variety of statistical
constraints (distribution of household types, sizes, age of household head,
difference of age between partners and among parents and children). Such a
population is often the initial state of microsimulation or (agent)
individual-based models. To get a realistic distribution of households is often
very important, because this distribution has an impact on the demographic
evolution. Usual techniques from microsimulation approach cross different
sources of aggregated data for generating individuals. In our case the number
of combinations of different households (types, sizes, age of participants)
makes it computationally difficult to use directly such methods. Hence we
developed a specific algorithm to make the problem more easily tractable.
Conclusions/Significance: We generate the populations of two pilot
municipalities in Auvergne region (France), to illustrate the approach. The
generated populations show a good agreement with the available statistical
datasets (not used for the generation) and are obtained in a reasonable
computational time.
|
0912.2828
|
Pulse Shaping, Localization and the Approximate Eigenstructure of LTV
Channels
|
cs.IT math.IT
|
In this article we show the relation between the theory of pulse shaping for
WSSUS channels and the notion of approximate eigenstructure for time-varying
channels. We consider pulse shaping for a general signaling scheme, called
Weyl-Heisenberg signaling, which includes OFDM with cyclic prefix and
OFDM/OQAM. The pulse design problem in the view of optimal WSSUS--averaged SINR
is an interplay between localization and "orthogonality". The localization
problem itself can be expressed in terms of eigenvalues of localization
operators and is intimately connected to the concept of approximate
eigenstructure of LTV channel operators. In fact, on the L_2-level both are
equivalent as we will show. The concept of "orthogonality" in turn can be
related to notion of tight frames. The right balance between these two sides is
still an open problem. However, several statements on achievable values of
certain localization measures and fundamental limits on SINR can already be
made as will be shown in the paper.
|
0912.2843
|
Intrusion Detection In Mobile Ad Hoc Networks Using GA Based Feature
Selection
|
cs.NE cs.CR cs.LG
|
Mobile ad hoc networking (MANET) has become an exciting and important
technology in recent years because of the rapid proliferation of wireless
devices. MANETs are highly vulnerable to attacks due to the open medium,
dynamically changing network topology and lack of centralized monitoring point.
It is important to search new architecture and mechanisms to protect the
wireless networks and mobile computing application. IDS analyze the network
activities by means of audit data and use patterns of well-known attacks or
normal profile to detect potential attacks. There are two methods to analyze:
misuse detection and anomaly detection. Misuse detection is not effective
against unknown attacks and therefore, anomaly detection method is used. In
this approach, the audit data is collected from each mobile node after
simulating the attack and compared with the normal behavior of the system. If
there is any deviation from normal behavior then the event is considered as an
attack. Some of the features of collected audit data may be redundant or
contribute little to the detection process. So it is essential to select the
important features to increase the detection rate. This paper focuses on
implementing two feature selection methods namely, markov blanket discovery and
genetic algorithm. In genetic algorithm, bayesian network is constructed over
the collected features and fitness function is calculated. Based on the fitness
value the features are selected. Markov blanket discovery also uses bayesian
network and the features are selected depending on the minimum description
length. During the evaluation phase, the performances of both approaches are
compared based on detection rate and false alarm rate.
|
0912.2846
|
Multi-valued Action Languages in CLP(FD)
|
cs.AI cs.LO cs.PL
|
Action description languages, such as A and B, are expressive instruments
introduced for formalizing planning domains and planning problem instances. The
paper starts by proposing a methodology to encode an action language (with
conditional effects and static causal laws), a slight variation of B, using
Constraint Logic Programming over Finite Domains. The approach is then
generalized to raise the use of constraints to the level of the action language
itself. A prototype implementation has been developed, and the preliminary
results are presented and discussed.
To appear in Theory and Practice of Logic Programming (TPLP)
|
0912.2881
|
Representing human and machine dictionaries in Markup languages
|
cs.CL
|
In this chapter we present the main issues in representing machine readable
dictionaries in XML, and in particular according to the Text Encoding
Dictionary (TEI) guidelines.
|
0912.3029
|
Interference Alignment and a Noisy Interference Regime for Many-to-One
Interference Channels
|
cs.IT math.IT
|
We study the capacity of discrete memoryless many-to-one interference
channels, i.e., K user interference channels where only one receiver faces
interference. For a class of many-to-one interference channels, we identify a
noisy interference regime, i.e., a regime where random coding and treating
interference as noise achieves sum-capacity. Specializing our results to the
Gaussian MIMO many-to-one interference channel, which is a special case of the
class of channels considered, we obtain new capacity results. Firstly, we
extend the noisy interference regime, previously studied for (many-to-one)
interference channels with average power constraints on the inputs, to a more
general class of inputs. This more general class includes the practical
scenario of inputs being restricted to fixed finite-size constellations such as
PSK or QAM. Secondly, we extend noisy interference results previously studied
in SISO interference channels with full channel state information (CSI) at all
nodes, to MIMO and parallel Gaussian many-to-one interference channels, and to
fading Gaussian many-to-one interference channels without CSI at the
transmitters. While the many-to-one interference channel requires interference
alignment, which in turn requires structured codes in general, we argue that in
the noisy interference regime, interference is implicitly aligned by random
coding irrespective of the input distribution. As a byproduct of our study, we
identify a second class of many-to-one interference channels (albeit
deterministic) where random coding is optimal (though interference is not
treated as noise). The optimality of random coding in this second class of
channels is due to an interference resolvability condition which precludes
interference alignment and hence obviates the need of structured codes.
|
0912.3036
|
Proceedings 8th International Workshop on Parallel and Distributed
Methods in verifiCation
|
cs.LO cs.CE cs.DC cs.SE
|
The 8th International Workshop on Parallel and Distributed Methods in
verifiCation (PDMC 2009) took place on November 4, 2009 at the Eindhoven
University of Technology, in conjunction with Formal Methods 2009 and other
related events for the first time under the heading of Formal Methods Week.
This volume contains the final workshop proceedings.
|
0912.3067
|
A Recursive Formula for Power Moments of 2-Dimensional Kloosterman Sums
Assiciated with General Linear Groups
|
math.NT cs.IT math.IT
|
In this paper, we construct a binary linear code connected with the
Kloosterman sum for $GL(2,q)$. Here $q$ is a power of two. Then we obtain a
recursive formula generating the power moments 2-dimensional Kloosterman sum,
equivalently that generating the even power moments of Kloosterman sum in terms
of the frequencies of weights in the code. This is done via Pless power moment
identity and by utilizing the explicit expression of the Kloosterman sum for
$GL(2,q)$.
|
0912.3134
|
Complexity of Propositional Abduction for Restricted Sets of Boolean
Functions
|
cs.CC cs.AI cs.LO
|
Abduction is a fundamental and important form of non-monotonic reasoning.
Given a knowledge base explaining how the world behaves it aims at finding an
explanation for some observed manifestation. In this paper we focus on
propositional abduction, where the knowledge base and the manifestation are
represented by propositional formulae. The problem of deciding whether there
exists an explanation has been shown to be SigmaP2-complete in general. We
consider variants obtained by restricting the allowed connectives in the
formulae to certain sets of Boolean functions. We give a complete
classification of the complexity for all considerable sets of Boolean
functions. In this way, we identify easier cases, namely NP-complete and
polynomial cases; and we highlight sources of intractability. Further, we
address the problem of counting the explanations and draw a complete picture
for the counting complexity.
|
0912.3228
|
On Backtracking in Real-time Heuristic Search
|
cs.AI
|
Real-time heuristic search algorithms are suitable for situated agents that
need to make their decisions in constant time. Since the original work by Korf
nearly two decades ago, numerous extensions have been suggested. One of the
most intriguing extensions is the idea of backtracking wherein the agent
decides to return to a previously visited state as opposed to moving forward
greedily. This idea has been empirically shown to have a significant impact on
various performance measures. The studies have been carried out in particular
empirical testbeds with specific real-time search algorithms that use
backtracking. Consequently, the extent to which the trends observed are
characteristic of backtracking in general is unclear. In this paper, we present
the first entirely theoretical study of backtracking in real-time heuristic
search. In particular, we present upper bounds on the solution cost exponential
and linear in a parameter regulating the amount of backtracking. The results
hold for a wide class of real-time heuristic search algorithms that includes
many existing algorithms as a small subclass.
|
0912.3245
|
Structured Error Recovery for Codeword-Stabilized Quantum Codes
|
quant-ph cs.IT math.IT
|
Codeword stabilized (CWS) codes are, in general, non-additive quantum codes
that can correct errors by an exhaustive search of different error patterns,
similar to the way that we decode classical non-linear codes. For an n-qubit
quantum code correcting errors on up to t qubits, this brute-force approach
consecutively tests different errors of weight t or less, and employs a
separate n-qubit measurement in each test. In this paper, we suggest an error
grouping technique that allows to simultaneously test large groups of errors in
a single measurement. This structured error recovery technique exponentially
reduces the number of measurements by about 3^t times. While it still leaves
exponentially many measurements for a generic CWS code, the technique is
equivalent to syndrome-based recovery for the special case of additive CWS
codes.
|
0912.3264
|
Random Access: An Information-Theoretic Perspective
|
cs.IT math.IT
|
This paper considers a random access system where each sender can be in two
modes of operation, active or not active, and where the set of active users is
available to a common receiver only. Active transmitters encode data into
independent streams of information, a subset of which are decoded by the
receiver, depending on the value of the collective interference. The main
contribution is to present an information-theoretic formulation of the problem
which allows us to characterize, with a guaranteed gap to optimality, the rates
that can be achieved by different data streams.
Our results are articulated as follows. First, we exactly characterize the
capacity region of a two-user system assuming a binary-expansion deterministic
channel model. Second, we extend this result to a two-user additive white
Gaussian noise channel, providing an approximate characterization within
$\sqrt{3}/2$ bit of the actual capacity. Third, we focus on the symmetric
scenario in which users are active with the same probability and subject to the
same received power constraint, and study the maximum achievable expected
sum-rate, or throughput, for any number of users. In this case, for the
symmetric binary expansion deterministic channel (which is related to the
packet collision model used in the networking literature), we show that a
simple coding scheme which does not employ superposition coding achieves the
system throughput. This result also shows that the performance of slotted ALOHA
systems can be improved by allowing encoding rate adaptation at the
transmitters. For the symmetric additive white Gaussian noise channel, we
propose a scheme that is within one bit of the system throughput for any value
of the underlying parameters.
|
0912.3275
|
A Formal Framework for Mobile Robot Patrolling in Arbitrary Environments
with Adversaries
|
cs.GT cs.MA
|
Using mobile robots for autonomous patrolling of environments to prevent
intrusions is a topic of increasing practical relevance. One of the most
challenging scientific issues is the problem of finding effective patrolling
strategies that, at each time point, determine the next moves of the patrollers
in order to maximize some objective function. In the very last years this
problem has been addressed in a game theoretical fashion, explicitly
considering the presence of an adversarial intruder. The general idea is that
of modeling a patrolling situation as a game, played by the patrollers and the
intruder, and of studying the equilibria of this game to derive effective
patrolling strategies. In this paper we present a game theoretical formal
framework for the determination of effective patrolling strategies that extends
the previous proposals appeared in the literature, by considering environments
with arbitrary topology and arbitrary preferences for the agents. The main
original contributions of this paper are the formulation of the patrolling game
for generic graph environments, an algorithm for finding a deterministic
equilibrium strategy, which is a fixed path through the vertices of the graph,
and an algorithm for finding a non-deterministic equilibrium strategy, which is
a set of probabilities for moving between adjacent vertices of the graph. Both
the algorithms are analytically studied and experimentally validated, to assess
their properties and efficiency.
|
0912.3309
|
New Generalization Bounds for Learning Kernels
|
cs.AI
|
This paper presents several novel generalization bounds for the problem of
learning kernels based on the analysis of the Rademacher complexity of the
corresponding hypothesis sets. Our bound for learning kernels with a convex
combination of p base kernels has only a log(p) dependency on the number of
kernels, p, which is considerably more favorable than the previous best bound
given for the same problem. We also give a novel bound for learning with a
linear combination of p base kernels with an L_2 regularization whose
dependency on p is only in p^{1/4}.
|
0912.3323
|
Minimizing Sum-MSE Implies Identical Downlink and Dual Uplink Power
Allocations
|
cs.IT math.IT
|
In the multiuser downlink, power allocation for linear precoders that
minimize the sum of mean squared errors under a sum power constraint is a
non-convex problem. Many existing algorithms solve an equivalent convex problem
in the virtual uplink and apply a transformation based on uplink-downlink
duality to find a downlink solution. In this letter, we analyze the optimality
criteria for the power allocation subproblem in the virtual uplink, and
demonstrate that the optimal solution leads to identical power allocations in
the downlink and virtual uplink. We thus extend the known duality results and,
importantly, simplify the existing algorithms used for iterative transceiver
design.
|
0912.3419
|
Application Driven Joint Uplink-Downlink Optimization in Wireless
Communications
|
cs.IT math.IT
|
This paper introduces a new mathematical framework, which is used to derive
joint uplink/downlink achievable rate regions for multi-user spatial
multiplexing between one base station and multiple terminals. The framework
consists of two models: the first one is a simple transmission model for uplink
and downlink, which is capable to give a lower bound on the capacity for the
case that the transmission is subject to imperfect CSI. A detailed model for
concrete channel estimation and feedback schemes provides parameter input to
the former model and covers the most important aspects such as pilot design
optimization, linear channel estimation, feedback delay, and feedback
quantization. We apply this framework to determine optimal pilot densities and
CSI feedback quantity, given that a weighted sum of uplink and downlink
throughput is to be maximized for a certain user velocity. We show that for low
speed, and if downlink throughput is of particular importance, a significant
portion of the uplink should be invested into CSI feedback. At higher velocity,
however, downlink performance becomes mainly affected by CSI feedback delay,
and hence CSI feedback brings little gain considering the inherent sacrifice of
uplink capacity. We further show that for high velocities, it becomes
beneficial to use no CSI feedback at all, but apply random beamforming in the
downlink and operate in time-division duplex.
|
0912.3441
|
On Space-Time Capacity Limits in Mobile and Delay Tolerant Networks
|
cs.NI cs.IT math.IT
|
We investigate the fundamental capacity limits of space-time journeys of
information in mobile and Delay Tolerant Networks (DTNs), where information is
either transmitted or carried by mobile nodes, using store-carry-forward
routing. We define the capacity of a journey (i.e., a path in space and time,
from a source to a destination) as the maximum amount of data that can be
transferred from the source to the destination in the given journey. Combining
a stochastic model (conveying all possible journeys) and an analysis of the
durations of the nodes' encounters, we study the properties of journeys that
maximize the space-time information propagation capacity, in bit-meters per
second. More specifically, we provide theoretical lower and upper bounds on the
information propagation speed, as a function of the journey capacity. In the
particular case of random way-point-like models (i.e., when nodes move for a
distance of the order of the network domain size before changing direction), we
show that, for relatively large journey capacities, the information propagation
speed is of the same order as the mobile node speed. This implies that,
surprisingly, in sparse but large-scale mobile DTNs, the space-time information
propagation capacity in bit-meters per second remains proportional to the
mobile node speed and to the size of the transported data bundles, when the
bundles are relatively large. We also verify that all our analytical bounds are
accurate in several simulation scenarios.
|
0912.3461
|
Application of Graph Coloring to Biological Networks
|
cs.CE q-bio.QM
|
We explore the application of graph coloring to biological networks,
specifically protein-protein interaction (PPI) networks. First, we find that
given similar conditions (i.e. number of nodes, number of links, degree
distribution and clustering), fewer colors are needed to color disassortative
(high degree nodes tend to connect to low degree nodes and vice versa) than
assortative networks. Fewer colors create fewer independent sets which in turn
imply higher concurrency potential for a network. Since PPI networks tend to be
disassortative, we suggest that in addition to functional specificity and
stability proposed previously by Maslov and Sneppen (Science 296, 2002), the
disassortative nature of PPI networks may promote the ability of cells to
perform multiple, crucial and functionally diverse tasks concurrently. Second,
since graph coloring is closely related to the presence of cliques in a graph,
the significance of node coloring information to the problem of identifying
protein complexes, i.e. dense subgraphs in a PPI network, is investigated. We
find that for PPI networks where 1% to 11% of nodes participate in at least one
identified protein complex, such as H. sapien (DIP20070219, DIP20081014 and
HPRD070609), DSATUR (a well-known complete graph coloring algorithm) node
coloring information can improve the quality (homogeneity and separation) of
initial candidate complexes. This finding may help to improve existing protein
complex detection methods, and/or suggest new methods.
|
0912.3503
|
Absolutely Secure Communications by Johnson-like Noise and Kirchhoff's
Laws
|
physics.gen-ph cond-mat.stat-mech cs.IT math.IT quant-ph
|
We survey the most important results and some recent developments about the
secure key exchange protocol where the security is based on the Second Law of
Thermodynamics and the robustness of classical physical information. We
conclude that a classical physical system offers a higher level of control and
security during the communication. We also mention some recent attempts
inspired by this communicator to create other systems where Alice and Bob do
not form an organic single system and/or the Second Law is irrelevant. It seems
philosophically that they cannot be unconditionally secure, however it is yet
an open question how to crack them; how can they be best used for conditionally
secure communications, and what are the practical implications.
|
0912.3541
|
Spectrum Sharing as Network Congestion Games
|
cs.IT cs.GT math.IT math.OC
|
This paper has been withdrawn by the first author due to incomplete
bibliography and incorporation of multiple formats in the same file.
|
0912.3589
|
Matching 2-D Ellipses to 3-D Circles with Application to Vehicle Pose
Estimation
|
cs.CV
|
Finding the three-dimensional representation of all or a part of a scene from
a single two dimensional image is a challenging task. In this paper we propose
a method for identifying the pose and location of objects with circular
protrusions in three dimensions from a single image and a 3d representation or
model of the object of interest. To do this, we present a method for
identifying ellipses and their properties quickly and reliably with a novel
technique that exploits intensity differences between objects and a geometric
technique for matching an ellipse in 2d to a circle in 3d.
We apply these techniques to the specific problem of determining the pose and
location of vehicles, particularly cars, from a single image. We have achieved
excellent pose recovery performance on artificially generated car images and
show promising results on real vehicle images. We also make use of the ellipse
detection method to identify car wheels from images, with a very high
successful match rate.
|
0912.3599
|
Robust Principal Component Analysis?
|
cs.IT math.IT
|
This paper is about a curious phenomenon. Suppose we have a data matrix,
which is the superposition of a low-rank component and a sparse component. Can
we recover each component individually? We prove that under some suitable
assumptions, it is possible to recover both the low-rank and the sparse
components exactly by solving a very convenient convex program called Principal
Component Pursuit; among all feasible decompositions, simply minimize a
weighted combination of the nuclear norm and of the L1 norm. This suggests the
possibility of a principled approach to robust principal component analysis
since our methodology and results assert that one can recover the principal
components of a data matrix even though a positive fraction of its entries are
arbitrarily corrupted. This extends to the situation where a fraction of the
entries are missing as well. We discuss an algorithm for solving this
optimization problem, and present applications in the area of video
surveillance, where our methodology allows for the detection of objects in a
cluttered background, and in the area of face recognition, where it offers a
principled way of removing shadows and specularities in images of faces.
|
0912.3747
|
A Survey of Paraphrasing and Textual Entailment Methods
|
cs.CL cs.AI
|
Paraphrasing methods recognize, generate, or extract phrases, sentences, or
longer natural language expressions that convey almost the same information.
Textual entailment methods, on the other hand, recognize, generate, or extract
pairs of natural language expressions, such that a human who reads (and trusts)
the first element of a pair would most likely infer that the other element is
also true. Paraphrasing can be seen as bidirectional textual entailment and
methods from the two areas are often similar. Both kinds of methods are useful,
at least in principle, in a wide range of natural language processing
applications, including question answering, summarization, text generation, and
machine translation. We summarize key ideas from the two areas by considering
in turn recognition, generation, and extraction methods, also pointing to
prominent articles and resources.
|
0912.3848
|
Wavelets on Graphs via Spectral Graph Theory
|
math.FA cs.IT math.IT
|
We propose a novel method for constructing wavelet transforms of functions
defined on the vertices of an arbitrary finite weighted graph. Our approach is
based on defining scaling using the the graph analogue of the Fourier domain,
namely the spectral decomposition of the discrete graph Laplacian $\L$. Given a
wavelet generating kernel $g$ and a scale parameter $t$, we define the scaled
wavelet operator $T_g^t = g(t\L)$. The spectral graph wavelets are then formed
by localizing this operator by applying it to an indicator function. Subject to
an admissibility condition on $g$, this procedure defines an invertible
transform. We explore the localization properties of the wavelets in the limit
of fine scales. Additionally, we present a fast Chebyshev polynomial
approximation algorithm for computing the transform that avoids the need for
diagonalizing $\L$. We highlight potential applications of the transform
through examples of wavelets on graphs corresponding to a variety of different
problem domains.
|
0912.3882
|
Science overlay maps: a new tool for research policy and library
management
|
cs.DL cs.IR physics.soc-ph
|
We present a novel approach to visually locate bodies of research within the
sciences, both at each moment of time and dynamically. This article describes
how this approach fits with other efforts to locally and globally map
scientific outputs. We then show how these science overlay maps help benchmark,
explore collaborations, and track temporal changes, using examples of
universities, corporations, funding agencies, and research topics. We address
conditions of application, with their advantages, downsides and limitations.
Overlay maps especially help investigate the increasing number of scientific
developments and organisations that do not fit within traditional disciplinary
categories. We make these tools accessible to help researchers explore the
ongoing socio-cognitive transformation of science and technology systems.
|
0912.3907
|
Efficient Linear Programming Decoding of HDPC Codes
|
cs.IT math.IT
|
We propose several improvements for Linear Programming (LP) decoding
algorithms for High Density Parity Check (HDPC) codes. First, we use the
automorphism groups of a code to create parity check matrix diversity and to
generate valid cuts from redundant parity checks. Second, we propose an
efficient mixed integer decoder utilizing the branch and bound method. We
further enhance the proposed decoders by removing inactive constraints and by
adapting the parity check matrix prior to decoding according to the channel
observations. Based on simulation results the proposed decoders achieve near-ML
performance with reasonable complexity.
|
0912.3917
|
Speech Recognition Oriented Vowel Classification Using Temporal Radial
Basis Functions
|
cs.CL cs.MM
|
The recent resurgence of interest in spatio-temporal neural network as speech
recognition tool motivates the present investigation. In this paper an approach
was developed based on temporal radial basis function "TRBF" looking to many
advantages: few parameters, speed convergence and time invariance. This
application aims to identify vowels taken from natural speech samples from the
Timit corpus of American speech. We report a recognition accuracy of 98.06
percent in training and 90.13 in test on a subset of 6 vowel phonemes, with the
possibility to expend the vowel sets in future.
|
0912.3924
|
A Study on Feature Selection Techniques in Educational Data Mining
|
cs.DB
|
Educational data mining (EDM) is a new growing research area and the essence
of data mining concepts are used in the educational field for the purpose of
extracting useful information on the behaviors of students in the learning
process. In this EDM, feature selection is to be made for the generation of
subset of candidate variables. As the feature selection influences the
predictive accuracy of any performance model, it is essential to study
elaborately the effectiveness of student performance model in connection with
feature selection techniques. In this connection, the present study is devoted
not only to investigate the most relevant subset features with minimum
cardinality for achieving high predictive performance by adopting various
filtered feature selection techniques in data mining but also to evaluate the
goodness of subsets with different cardinalities and the quality of six
filtered feature selection algorithms in terms of F-measure value and Receiver
Operating Characteristics (ROC) value, generated by the NaiveBayes algorithm as
base-line classifier method. The comparative study carried out by us on six
filter feature section algorithms reveals the best method, as well as optimal
dimensionality of the feature subset. Benchmarking of filter feature selection
method is subsequently carried out by deploying different classifier models.
The result of the present study effectively supports the well known fact of
increase in the predictive accuracy with the existence of minimum number of
features. The expected outcomes show a reduction in computational time and
constructional cost in both training and classification phases of the student
performance model.
|
0912.3956
|
Modeling and Application of Series Elastic Actuators for Force Control
Multi Legged Robots
|
cs.RO
|
Series Elastic Actuators provide many benefits in force control of robots in
unconstrained environments. These benefits include high force fidelity,
extremely low impedance, low friction, and good force control bandwidth. Series
Elastic Actuators employ a novel mechanical design architecture which goes
against the common machine design principal of "stiffer is better". A compliant
element is placed between the gear train and driven load to intentionally
reduce the stiffness of the actuator. A position sensor measures the
deflection, and the force output is accurately calculated using Hooke's Law
(F=Kx). A control loop then servos the actuator to the desired output force.
The resulting actuator has inherent shock tolerance, high force fidelity and
extremely low impedance. These characteristics are desirable in many
applications including legged robots, exoskeletons for human performance
amplification, robotic arms, haptic interfaces, and adaptive suspensions. We
describe several variations of Series Elastic Actuators that have been
developed using both electric and hydraulic components.
|
0912.3957
|
Realization of Semantic Atom Blog
|
cs.IR
|
Web blog is used as a collaborative platform to publish and share
information. The information accumulated in the blog intrinsically contains the
knowledge. The knowledge shared by the community of people has intangible value
proposition. The blog is viewed as a multimedia information resource available
on the Internet. In a blog, information in the form of text, image, audio and
video builds up exponentially. The multimedia information contained in an Atom
blog does not have the capability, which is required by the software processes
so that Atom blog content can be accessed, processed and reused over the
Internet. This shortcoming is addressed by exploring OWL knowledge modeling,
semantic annotation and semantic categorization techniques in an Atom blog
sphere. By adopting these techniques, futuristic Atom blogs can be created and
deployed over the Internet.
|
0912.3960
|
Optimal Design of Fuzzy Based Power System Stabilizer Self Tuned by
Robust Search Algorithm
|
cs.NE
|
In the interconnected power system network, instability problems are caused
mainly by the low frequency oscillations of 0.2 to 2.5 Hz. The supplementary
control signal in addition with AVR and high gain excitation systems are
provided by means of Power System Stabilizer (PSS). Conventional power system
stabilizers provide effective damping only on a particular operating point. But
fuzzy based PSS provides good damping for a wide range of operating points. The
bottlenecks faced in designing a fuzzy logic controller can be minimized by
using appropriate optimization techniques like Genetic Algorithm, Particle Swam
Optimization, Ant Colony Optimization etc.In this paper the membership
functions of FLC are optimized by the new breed optimization technique called
Genetic Algorithm. This design methodology is implemented on a Single Machine
Infinite Bus (SMIB) system. Simulation results on SMIB show the effectiveness
and robustness of the proposed PSS over a wide range of operating conditions
and system configurations.
|
0912.3961
|
Enhancing Multi-Agent Based Simulation with Human-Agents Interactive
Spatial Behaviour
|
cs.MA
|
We are exploring the enhancement of models of agent behaviour with more
"human-like" decision making strategies than are presently available. Our
motivation is to developed with a view to as the decision analysis and support
for electric taxi company under the mission of energy saving and reduction of
CO2, in particular car-pool and car-sharing management policies. In order to
achieve the object of decision analysis for user, we provide a human-agents
interactive spatial behaviour to support user making decision real time. We
adopt passenger average waiting time and electric taxi average idle time as the
performance measures and decision support fro electric taxi company. Finally,
according to the analysis result, we demonstrate that our multi-agent
simulation and GUI can help users or companies quickly make a quality and
accurate decision to reduce the decision-making cost and time.
|
0912.3964
|
A Novel Channel Coding for Progressive Transmission of Medical Images
|
cs.IT math.IT
|
A novel channel coding scheme for progressive transmission of large images is
proposed. The transmission time, low distortion reconstructed image and low
complexity are most concerned in this paper. In the case of medical data
transmission, it is vital to keep the distortion level under control as in most
of the cases certain clinically important regions have to be transmitted
without any visible error. The proposed system significantly reduces the
transmission time and error. The progressive transmission is based on the
process that the input image is decomposed into many subblocks each to be
coded, compressed, and transmitted individually. Therefore, firstly the image
is segmented into a number of subblocks and then the discrete wavelet transform
decomposes each subblock into different time-frequency components. Finally the
components are coded for error control and transmitted. The complete system is
coded in VHDL. In the proposed system, we choose a 3-level Haar wavelet
transform to perform the wavelet transform for each subblock. It is simple,
faster and easier to implement when compared with other transform method. The
channel coding used here is Hamming code which is a simpler and efficient
forward error control code.
|
0912.3973
|
A Novel Feature Extraction for Robust EMG Pattern Recognition
|
cs.CV
|
Varieties of noises are major problem in recognition of Electromyography
(EMG) signal. Hence, methods to remove noise become most significant in EMG
signal analysis. White Gaussian noise (WGN) is used to represent interference
in this paper. Generally, WGN is difficult to be removed using typical
filtering and solutions to remove WGN are limited. In addition, noise removal
is an important step before performing feature extraction, which is used in
EMG-based recognition. This research is aimed to present a novel feature that
tolerate with WGN. As a result, noise removal algorithm is not needed. Two
novel mean and median frequencies (MMNF and MMDF) are presented for robust
feature extraction. Sixteen existing features and two novelties are evaluated
in a noisy environment. WGN with various signal-to-noise ratios (SNRs), i.e.
20-0 dB, was added to the original EMG signal. The results showed that MMNF
performed very well especially in weak EMG signal compared with others. The
error of MMNF in weak EMG signal with very high noise, 0 dB SNR, is about 5-10
percent and closed by MMDF and Histogram, whereas the error of other features
is more than 20 percent. While in strong EMG signal, the error of MMNF is
better than those from other features. Moreover, the combination of MMNF,
Histrogram of EMG and Willison amplitude is used as feature vector in
classification task. The experimental result shows the better recognition
result in noisy environment than other success feature candidates. From the
above results demonstrate that MMNF can be used for new robust feature
extraction.
|
0912.3978
|
Diversity-Multiplexing Tradeoff in Multi-Antenna Multi-Relay Networks:
Improvements and Some Optimality Results
|
cs.IT math.IT
|
This paper investigates the benefits of Amplify-and-Forward (AF) relaying in
the setup of multi-antenna wireless networks. The concept of Random Sequential
(RS) relaying is previously introduced in the literature and showed that it
achieves the maximum diversity gain in a general multi-antenna network. Here,
we show that random unitary matrix multiplication at the relay nodes empowers
the RS scheme to achieve a better Diversity-Multiplexing Tradeoff (DMT) as
compared to the traditional AF relaying. First, we study the case of a
multi-antenna full-duplex single-relay two-hop network, for which we show that
the RS achieves the optimum DMT. Applying this result, we derive a new
achievable DMT for the case of multi-antenna half-duplex parallel relay
network. Interestingly, it turns out that the DMT of the RS scheme is optimum
for the case of multi-antenna two parallel non-interfering half-duplex relays.
Next, we show that random unitary matrix multiplication also improves the DMT
of the Non-Orthogonal AF relaying scheme in the case of a multi-antenna single
relay channel. Finally, we study the general case of multi-antenna full-duplex
relay networks and derive a new lower-bound on its DMT using the RS scheme.
|
0912.3981
|
Multiplexing Gain of Amplify-Forward Relaying in Wireless Multi-Antenna
Relay Networks
|
cs.IT math.IT
|
This paper studies the general multi-antenna multiple-relay network. Every
two nodes of the network are either connected together through a Rayleigh
fading channel or disconnected. We study the ergodic capacity of the network in
the high SNR regime. We prove that the traditional amplify-forward relaying
achieves the maximum multiplexing gain of the network. Furthermore, we show
that the maximum multiplexing gain of the network is equal to the minimum
vertex cut-set of the underlying graph of the network, which can be computed in
polynomial time in terms of the number of network nodes. Finally, the argument
is extended to the multicast and multi-access scenarios.
|
0912.3983
|
Performance Analysis of AIM-K-means & K-means in Quality Cluster
Generation
|
cs.LG
|
Among all the partition based clustering algorithms K-means is the most
popular and well known method. It generally shows impressive results even in
considerably large data sets. The computational complexity of K-means does not
suffer from the size of the data set. The main disadvantage faced in performing
this clustering is that the selection of initial means. If the user does not
have adequate knowledge about the data set, it may lead to erroneous results.
The algorithm Automatic Initialization of Means (AIM), which is an extension to
K-means, has been proposed to overcome the problem of initial mean generation.
In this paper an attempt has been made to compare the performance of the
algorithms through implementation
|
0912.3984
|
Multi-Agent Model using Secure Multi-Party Computing in e-Governance
|
cs.MA
|
Information management and retrieval of all the citizen occurs in almost all
the public service functions. Electronic Government system is an emerging trend
in India through which efforts are made to strive maximum safety and security.
Various solutions for this have been proposed like Shibboleth, Public Key
Infrastructure, Smart Cards and Light Weight Directory Access Protocols. Still,
none of these guarantee 100 percent security. Efforts are being made to provide
common national identity solution to various diverse Government identity cards.
In this paper, we discuss issues related to these solutions.
|
0912.3995
|
Gaussian Process Optimization in the Bandit Setting: No Regret and
Experimental Design
|
cs.LG
|
Many applications require optimizing an unknown, noisy function that is
expensive to evaluate. We formalize this task as a multi-armed bandit problem,
where the payoff function is either sampled from a Gaussian process (GP) or has
low RKHS norm. We resolve the important open problem of deriving regret bounds
for this setting, which imply novel convergence rates for GP optimization. We
analyze GP-UCB, an intuitive upper-confidence based algorithm, and bound its
cumulative regret in terms of maximal information gain, establishing a novel
connection between GP optimization and experimental design. Moreover, by
bounding the latter in terms of operator spectra, we obtain explicit sublinear
regret bounds for many commonly used covariance functions. In some important
cases, our bounds have surprisingly weak dependence on the dimensionality. In
our experiments on real sensor data, GP-UCB compares favorably with other
heuristical GP optimization approaches.
|
0912.4012
|
Balancing Traffic in Networks: Redundancy, Learning and the Effect of
Stochastic Fluctuations
|
math.PR cs.GT cs.IT cs.NI math.IT
|
We study the distribution of traffic in networks whose users try to minimise
their delays by adhering to a simple learning scheme inspired by the replicator
dynamics of evolutionary game theory. The stable steady states of these
dynamics coincide with the network's Wardrop equilibria and form a convex
polytope whose dimension is determined by the network's redundancy (an
important concept which measures the "linear dependence" of the users' paths).
Despite this abundance of stationary points, the long-term behaviour of the
replicator dynamics turns out to be remarkably simple: every solution orbit
converges to a Wardrop equilibrium.
On the other hand, a major challenge occurs when the users' delays fluctuate
unpredictably due to random external factors. In that case, interior equilibria
are no longer stationary, but strict equilibria remain stochastically stable
irrespective of the fluctuations' magnitude. In fact, if the network has no
redundancy and the users are patient enough, we show that the long-term
averages of the users' traffic flows converge to the vicinity of an
equilibrium, and we also estimate the corresponding invariant measure.
|
0912.4107
|
New [48,16,16] Optimal Linear Binary Block Code
|
cs.IT math.IT
|
A new [48,16,16] optimal linear binary block code is given. To get this code
a general construction is used which is also described in this paper. The
construction of this new code settles an conjecture mentioned in a 2008 paper
by Janosov et al. where the authors found an new optimal [47,15,16]-code, which
is relevant to the applied construction.
|
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