abstract stringlengths 3 192k | title stringlengths 4 857 |
|---|---|
one of the increasing threats to functional spacecraft around earth is that of space debris. the risks that it poses for current and future space operations due to collisions are growing in an exponential manner. it is essential to create and maintain a catalog of space debris to monitor the space environment. optical ... | perturbations in the optimized boundary value initial orbit determination approach |
as advances in technology allow the acquisition of complementary information, it is increasingly common for scientific studies to collect multiple datasets. large-scale neuroimaging studies often include multiple modalities (e.g., task functional mri, resting-state fmri, diffusion mri, and/or structural mri), with the ... | simultaneous non-gaussian component analysis (sing) for data integration in neuroimaging |
tether systems have been used in space for various scopes since the beginning of the space era. they have been investigated as electrodynamics power generators or motors, momentum exchange and orbital stabilization assets or formation flying connection and pulling ropes. in the most recent years, in the context of esa ... | tethers as pulling capture technology for e.deorbit and harpoon-based adr missions |
the grand challenge of surface leak monitoring is to detect and attribute even small leaks across large energy development sites, which often span hundreds of square kilometres. ratio-based geochemical methods show great potential for near-surface leak detection and attribution in vehicle-based mobile surveys. ratios a... | mobile detection of fugitive emissions using computationally optimized geochemical methods |
southeastern saskatchewan (sk) is a major oil-producing region in central canada. mainly, the developed plays include the historic weyburn-midale unit (conventional), and bakken unit (unconventional). collectively, developments across these plays occupy about 10,000 km2. to help reduce fugitive emissions and venting in... | fugitive and vented gas emissions across conventional and unconventional oil developments in southeastern saskatchewan, canada |
with the expansion of the space industry, debris congestion has become a serious problem. when space debris collides with satellites in orbit, it may damage the satellites or, in the worst case, cause an explosion. while economic activity influences debris congestion, debris can also influence the economy. to what exte... | to what extent will space debris impact the economy? |
lakes are carbon gateways with immense processing capacity, acting as either sinks or sources for co2. as climate change exacerbates weather extremes, carbon stored within permafrost and soils is liberated to water systems, altering aquatic carbon budgets and light availability for photosynthesis. the functional respon... | temporally-resolved study of atmosphere-lake net co2 exchange at lochaber lake, nova scotia, canada |
the militarization of outer space and development of counterspace technologies is a growing concern, especially as commercial and governmental entities are sending thousands of satellites into orbit. anti-satellite (asat) tests and weapons put the sustainability of space at greater risks because the debris they generat... | on the increased risk of kessler syndrome by anti-satellite tests |
the main limitation of the currently adopted method for predicting spacecraft catastrophic fragmentation due to a collision with large debris is the total independence of the critical value of the energy-to-target mass ratio from both the satellite configuration and the impact point; in fact these two issues are not ac... | a contribution to the definition of a new method to predict the catastrophic disintegration of spacecraft after collision with large orbital debris |
this study characterizes the deposition profile for the current on-orbit massive derelicts (i.e., rocket bodies and nonoperational payloads) by country, orbit, and mass. this research provides context for ongoing debris collision risk analysis. | intact derelict deposition study |
this research simulates spacecraft explosions in cislunar space and analyzes the resulting risk to other notional spacecraft. three case studies are considered, which include simulations of spacecraft explosions during earth-moon hohmann transfers, along the manifold of the [formula: see text] earth-moon lagrange point... | debris collision risk analysis following simulated cislunar spacecraft explosions |
fire frequency and areal extent have been increasing for the past several decades in carbon-rich boreal and tundra ecosystems. the summer of 2015 was the second worst fire year on record in alaska. one of these 2015 alaskan fires burned within the yukon-kuskokwim delta (yk delta), where more area was burned in 2015 tha... | short-term impacts from the 2015 yukon-kuskokwim river delta tundra fire on permafrost vulnerability and c loss |
the development of nanosatellites raises the question of the evolution of risk posed by the increasing number of orbital debris to the sustainable use of space. in order to better understand and measure this increased risk, cnes' tech4spacecare initiative has granted an experimental and numerical study on the consequen... | on-ground hvi on a nanosatellite. impact test, fragments recovery and characterization, impact simulations |
this paper presents the modelling methodology and the results of a feasibility study of a device for just-in time collision avoidance (jca). the main principle of the proposed system is to generate a cloud intercepting the object trajectory and locally increasing the density, causing an aerodynamic drag force acting on... | space debris braking system using derivative srm for just-in time collision avoidance maneuver |
determining the risks from space debris involve a number of statistical calculations. these calculations inevitably involve assumptions about geometry — including the physical geometry of orbits and the geometry of satellites. a number of tools have been developed in nasa's orbital debris program office to handle these... | algorithms for the computation of debris risks |
nearly half of alberta's oil and gas related methane emissions are due to fugitives and leaks, which pose significant potential for mitigation. accurate and spatially-extensive emissions data can help operators and regulators meet reduction targets, and highlight which infrastructure requires immediate attention. this ... | baselining fugitive and vented emissions across canadian energy developments |
vehicle-based measurements of wind speed and direction are presently used for a range of applications, including gas plume detection. theoretically, vehicle-based measurements could also be integrated with fixed-site measurements to add spatial richness in weather and atmospheric observing systems, but the quality and ... | using fluid dynamics and field experiments to improve vehicle-based wind measurements for environmental monitoring |
equatorial satellites in low or medium altitude orbits have shown great potential for monitoring space debris in the geosynchronous belt and performing remote sensing tasks in low latitudes. however, the possibility of satellite collision between proposed equatorial satellites and existed spacecraft in sun-synchronous ... | design principles of equatorial satellite for the concerns of space debris |
we examined the occurrence and sources of 16 priority pahs in the water and sediment samples of the miankaleh wetland (coastal biosphere reserve), famous for harbouring huge flocks of migrating birds. the water and sediment samples collected from various locations were visualized and processed using a self-organizing m... | occurrence and source of pahs in miankaleh international wetland in iran |
fusion of ftir with h&e images reveals the contributions of collagen, dna and cytokeratin in metastatic/lymphoid tissue at high spatial resolution. a regression-based fusion algorithm has been used to merge hyperspectral fourier transform infrared (ftir) data with an h&e image of oral squamous cell carcinoma me... | tissue discrimination in head and neck cancer using image fusion of ir and optical microscopy |
over the past several decades, surface air temperatures in the arctic have increased at approximately twice the global rate, and climate models project that this rate of warming will continue through the century, with the greatest warming occurring during the winter months. carbon emissions during the cold season (i.e.... | a pan-arctic synthesis of cold season carbon emissions |
at the core of design-technology co-optimization (dtco) processes, is the design space exploration (dse), where different design schemes and patterns are systematically analyzed and design rules and processes are co-optimized for optimal yield and performance before real products are designed. synthetic layout generati... | approaches for full coverage physical design space exploration and analysis by synthetic layout generation |
the rising space debris population is becoming an increasing risk for space assets. even objects with the size of 10mm can cause major damages to active spacecraft. especially the orbits around 800km high are densely populated with space debris objects. to assess the risk of collisions with active satellites, the earth... | passive optical link budget for leo space surveillance |
parkinson’s disease patients present diminished coordination caused by neural degeneration. this leads to large motor difficulties during gait such as balance loss and pronounced forward inclination of the upper body. this work assessed the spinal sagittal plane angle alterations in two groups: six parkinsonian patient... | two-dimensional posture evaluation in parkinson’s disease: effect of loads on the spinal angle during gait. |
resident space object mass is a fundamental property and a key object characterization attribute. estimating the debris mass from fragmentation events provide insight into the root causes and symmetry of these events by considering the conservation of momentum. mass estimates of debris also enable an understanding if s... | estimating orbital debris mass via solar radiation pressure and photometric signatures |
canadian governments have pledged to cut energy sector methane emissions 40-45% below 2012 levels by 2025. site-level measurements of methane will guide reduction efforts and confirm the success of new regulation. however, available data are still sparse, and current reported inventories are disputed due to the discrep... | developing a better understanding of methane emissions patterns and inventories across major canadian energy developments |
spatio-temporal patterns of methane (ch4) and carbon dioxide (co2) release from natural sources needs to be better understood across the arctic region. climate change in the arctic is occurring at a pace that may be 2 to 4 times the global average, and existing measurements derive from a limited number of field sites, ... | characterization of atmospheric methane release at hotspots in the outer mackenzie river delta |
air temperature across the arctic has been increasing twice as fast as the global average, with the greatest warming occurring during the nongrowing season (ngs; late fall, winter, early spring). warming during the ngs may have a profound impact on belowground carbon storage because microbial respiration continues when... | a pan-arctic synthesis of nongrowing season respiration: key drivers and responses to a changing climate |
interest in lunar exploration, development, and utilization has been increasing in recent years. it is concerned that space debris is generated and accumulated around the moon as historically occurred in earth orbit if the development and utilization are massively conducted without sufficient measures. as demonstrated ... | orbital propagation to assess the lunar orbital debris and its collision risk onto the lunar surface |
spacecraft operating in low orbit are at risk of being hit by space debris. in the debris environment, the impact of debris is likely to cause the double satellite formation to exit science mode or even lead to the divergence of the control system, thus affecting the scientific exploration mission. in this paper, the a... | relative attitude stability analysis of double satellite formation for gravity field exploration in space debris environment |
the united states air force maintains the catalog of earth orbiting satellites, or satcat. in february of 2009, a collision between cosmos 2251 and iridium 33 occurred. this event not only generated thousands of pieces of debris, but also heightened international interest in preventing future orbital collisions. future... | trending analysis of historical conjunction data messages |
northern soils are vast reservoirs of carbon and even small changes in soil co2 respiration could significantly alter atmospheric concentrations. recent synthetic modeling studies have shown that the temperature sensitivity (q10) of soil respiration is most accurately solved using a combination of subsurface and surfac... | temperature sensitivity of northern soils using flux-concentration measurements and inversion analysis |
the presence of debris in earth's orbit poses a significant risk to human activity in outer space. this debris population continues to grow due to ground launches, loss of external parts from space ships, and uncontrollable collisions between objects. a computationally feasible continuum model for the growth of the deb... | a population dynamics approach to the distribution of space debris in low earth orbit |
the space community is nowadays aware of the space debris problems. in particular, the collision avoidance is a subject that is more and more studied. moreover, the specific problematic of collision avoidance during the launch phase of a spacecraft should be studied carefully because there are specific constraints to c... | vi. space traffic management: the 7th iaass conference |
due to increasing demand for food, intensive mariculture of finfish is a fast developing industry in the iranian part of the persian gulf (pg). the environmental impacts of cage fish farming largely involve release of excessive organic matter (biodeposits). careful monitoring of fish farms to avoid anoxia and bottom "d... | biodeposit dispersion around a deep cage finfish farm in the northern persian gulf |
a recent trilateral accord between north american governments pledges to cut energy sector methane emissions 40-45 per cent below 2012 levels by 2025. effective methane-reduction policy relies on accurate and spatially extensive emissions data. in this study, we assessed the feasibility of bottom-up data collection for... | baselining fugitive and vented emissions across canadian energy developments |
in the oil and gas industry, fugitive and vented releases of trace gases (co2, ch4 and h2s) are known to originate from many forms of infrastructure including well casings, pipelines and storage tanks. while emission factors for these infrastructure are widely known, we lack a good understanding from top-down studies o... | explaining seasonal variation of fugitive and vented emissions from upstream oil and gas infrastructure |
due to the biological, physical and chemical complexities of the soil environment, soil respiration is arguably the least well understood component of the terrestrial carbon balance. while chambers are commonly used to measure soil respiration, subsurface gradient approaches have become increasingly popular as solid-st... | in-situ diffusivity measurements using solid-state co2 sensors |
since about 15 years, esa's space debris office provides a service to support operational collision avoidance activities. this support currently covers the esa missions cryosat-2, sentinel-1a/b, sentinel-2a/b, sentinel-3a and the constellation of swarm-a/b/c in low-earth orbit and cluster-ii in highly eccentric orbit a... | current collision avoidance service by esa's space debris office |
estimating the density of space debris as a function of orbital elements and size is crucial for determining the risk of collision of spacecraft. for objects 1 cm or larger in diameter, this information can be obtained using beam park observations made with powerful ground based radars. this study presents a novel tech... | estimating the space debris density function using radar beam park measurements |
the likelihood of on-orbit breakups, whether spontaneous or the result of collision, will likely continue to grow as the barriers of entry to and use of space are reduced. in all orbitalregimes, especially low earth orbit (leo), preparation to respond quickly when the next breakup occurs is critical. this research util... | utilizing supercomputing to analyze risks of an emergent large-scale debris field in low earth orbit |
in recent years, energy sector methane emissions have been recorded in large part by applying modern non-industry-standard techniques. industry may lack the regulatory flexibility to use such techniques, or in some cases may not understand the possible associated economic advantage. as progressive jurisdictions move fr... | how much can non-industry standard measurement methodologies benefit methane reduction programs? |
simulations of spacecraft breakup events in low lunar orbit are conducted with the aim of determining the longevity of the resulting debris and the hazards it could pose. the trajectories of approximately 97,000 debris particles across eight monte carlo breakup simulations are propagated for 1 year using a high-precisi... | simulation of debris events in selected low lunar orbits |
radiocarbon co2 (δ14co2 ) is considered a useful tool for studying soil-respired co2 and its sources of production. previous surface soil gas measurement monitoring and verification (mmv) studies at aquistore, a carbon capture and storage (ccs) project in canada, have used δ14co2 as part of a geochemical mmv suite to h... | radiocarbon co2 in soil: investigating natural anomalies at the aquistore ccs project |
brain temperature is an understudied parameter relevant to brain injury and ischemia. to advance our understanding of thermal dynamics in the human brain, combined with the challenges of routine experimental measurements, a biophysical modeling framework was developed to facilitate individualized brain temperature pred... | comparisons of healthy human brain temperature predicted from biophysical modeling and measured with whole brain mr thermometry |
the oil and gas industry is canadas largest contributor to national methane (ch4) emissions. in order to quantify differences between producing regions, we conducted truck-based mobile ch4 surveys, stationary measurements (otm33a), and optical gas imaging in canadas heavy oil capital lloydminster in saskatchewan, and a... | methane emissions from three canadian oil and natural gas developments |
the mackenzie river delta is the second largest arctic river delta in the world. thin and destabilizing permafrost coupled with vast natural gas reserves at depth, high organic-content soils, and a high proportion of wetlands create a unique ecosystem conducive to high rates of methane (ch4) emission from biogenic and ... | characterization of atmospheric methane release in the outer mackenzie river delta from biogenic and thermogenic sources |
the number of satellites and space debris has increased alarmingly in recent years, such as risky encounters have increased, especially in the near earth region. the collision probability between space objects will increase constantly so that the analysis of high-risk conjunctions will become a time consuming task. the... | autonomous collision avoidance system |
methane emissions were measured at ~7000 sites across major oil and gas producing regions in canada to examine regional emission trends, and to derive an inventory estimate for canada's upstream oil and gas sector. emissions varied by fluid type and geographic region, with the heavy oil region of lloydminster ranking h... | methane emissions from upstream oil and gas production in canada are underestimated |
there is likely to be a surge of satellites launched into space over the next decade, which means the risk of collisions in space will rise along with risks to the sustainability of the space environment from debris. how can the sustainability of the space domain be protected in a looming new era of increasingly conges... | slash the trash: incentivizing deorbit |
in recent months, there have been several high-profile near-miss conjunction events [1], most notably of which, and of greatest concern, were those between two non-manoeuvrable space debris objects. to detect such a potentially catastrophic event, it is essential to search for conjunctions between all possible sets of ... | artificial intelligence for all vs. all conjunction screening |
the amount of orbital debris generated in low earth orbit has been steadily increasing. recently, deployments of large satellite constellations in low-earth orbit (leo) mean that the number of satellites in key orbits will increase at a much higher rate than seen historically, raising concerns over the sustainability o... | assessing debris removal services for large constellations |
space debris have become a persistent problem and a growing concern for operations of satellites orbiting around the earth, with several fragmentation events occurring every year. the increasing number of launches and operative satellites leads to the production of more debris, as the probability of collisions increase... | puzzle software for the characterisation of in-orbit fragmentations |
recently, there has been increased emphasis on satellites used for aspect of both our life and security. nec operates remote sensing satellite asnaro2, which was developed and operated in-house. on the other hand, an increase in the number of space objects (e.g. satellite constellation or debris), anti-satellite weapon... | notable object detection from tle based on deep metric learning |
in the ever-evolving landscape of satellite technology, the ability to effectively monitor and predict the trajectories of space objects is imperative. there is an escalating concern regarding the congestion of the space environment resulting from an increasing number of satellites, which poses risks of collision and t... | maneuver detection from tle data: a comparative analysis with emphasis on romanian contributions and current space activities |
arctic and boreal ecosystems are vast reservoirs of carbon and are particularly sensitive to climate warming. changes in the temperature and precipitation regimes of these regions could significantly alter soil respiration rates, impacting atmospheric concentrations and affecting climate change feedbacks. many incubati... | effect of soil moisture on the temperature sensitivity of northern soils |
among the over 23,000 catalogued objects orbiting the earth, only 6% represent actual active satellites. this number is quickly rising thanks to an increasing interest in space-based activities and an ever more affordable access to orbit. this situation entails that close conjunctions between space residents have becom... | network representation of in-orbit traffic for space situational awareness: a complex system perspective |
even a low failure rate means that dozens of satellites could lose control and become debris. because they are located in an operational orbit, they pose a serious problem. therefore, a few active debris removal (adr) ideas have been proposed, which is to tow and de-orbit debris satellites with rescue satellites simila... | study of laser ablation induced impulse for laser space debris removal |
the cryosat-2 mission was launched from baikonour cosmodrome on the 8th april 2010 aboard a dnepr launch vehicle (based on a modified ss18 satan icbm) into a near polar non-sun synchronous orbit at about 700 km altitude. cryosat-2 is an esa earth explorer mission operated from esoc/esa in darmstadt, with the prime obje... | cryosat-2 : in-orbit collision avoidance manoeuvre support tools and operation evolutions |
we develop a gaussian process ("gp") framework for modeling mortality rates and mortality improvement factors. gp regression is a nonparametric, data-driven approach for determining the spatial dependence in mortality rates and jointly smoothing raw rates across dimensions, such as calendar year and age. the gp model q... | gaussian process models for mortality rates and improvement factors |
bandt and pompe introduced permutation entropy in 2002 for time series where equal values, xt1 = xt2, t1 = t2, were neglected and only inequalities between the xt were considered. since then, this measure has been modified and extended, in particular in cases when the amount of equal values in the series can not be neg... | an empirical evaluation of alternative methods of estimation for permutation entropy in time series with tied values |
the space debris problematic is directly linked to the inorbit collision risk between artificial satellites. with the increase of the space constellation projects, a multiplication of multi-payload launches should occur. in the specific cases where many satellites are injected into orbit with the same launcher upper st... | optimization of constellation jettisoning regards to short term collision risks |
the massive collision monitoring activity has been conducted since 2014 to monitor and characterize the encounter dynamics of massive derelicts in low earth orbit. this activity has identified critical clusters of high debris-generating potential. however, the constant evolution of the debris environment due to continu... | updating the massive collision monitoring activity - creating a collision risk continuum |
space debris has grown to be a significant problem for outer space activities. the remnants of human activities in space are very diverse; they can be tiny paint flakes, all sorts of fragments, or entirely intact—but otherwise nonfunctional spacecraft and rocket bodies. the amount of debris is increasing at a growing p... | legal consequences of the pollution of outer space with space debris |
more than 90% of the space objects orbiting around the earth are space debris. since the orbits of these debris often overlap the trajectories of spacecraft, they create a potential collision risk. the problem of removing the most dangerous space debris can be modeled as a biobjective time dependent traveling salesman ... | a biobjective branch and bound procedure for planning spatial missions |
recent studies have highlighted fluctuations in the carbon isotope content (δ13c) of co2 produced by soil respiration. these have been correlated with diel cycles of environmental forcing (e.g., soil temperature), or with synoptic weather events (e.g., rain events and pressure-induced ventilation). we used an extensive... | environmental forcing does not lead to variation in carbon isotope content of forest soil respiration |
presently, fugitive emissions released into the atmosphere during the completion and production of oil and gas wells are poorly regulated within canada. some possible upstream sources of these emissions include flowback during well completions, liquid unloading, chemical injection pumps, and equipment leaks. the enviro... | fugitive emissions from conventional and hydraulically fractured natural gas developments in western canada |
physical soil properties create lags between temperature change and corresponding soil responses, which obscure true q10 values and other biophysical parameters such as depth of production. this study examines an inversion approach for estimating q10 and depth of production (zp) using physically based soil models, cons... | an inversion approach for determining production depth and temperature sensitivity of soil respiration |
groundwater methane in areas of fossil fuel development has been a recent focus of study as high methane (ch4) concentrations pose water quality concerns and potential explosive hazards. in this study, we used groundwater and ambient air ch4 surveys to investigate ch4 distribution and sources in the stellarton basin of... | occurrence and origin of groundwater methane in proximity to legacy coal mines in nova scotia |
spacecraft orbiting in low earth orbit (leo) undergo complex and poorly understood interactions with their environment leading to large uncertainties in predicting orbits and an associated risk of collision with other satellites and space debris. the drag of orbiting spacecraft represents one of the largest sources of ... | development of a high-speed, rarefied plasma wind tunnel for ionospheric aerodynamics research |
while the dependence on space expands in our normal life, the risks for space systems are also increasing, caused by congested space debris, and contesting, challenging space activities. reflecting these backgrounds, the japanese government designated the jmod(japan ministry of defense) under the basic plan on space po... | commercial ssa capability in japan |
the monitoring of space debris and satellites orbiting around earth is an essential topic in the space surveillance. the impact of debris, even of small size, against active spatial installations causes serious damage, malfunctions and potential service interruptions. collision-avoidance maneuverings are often performe... | space debris monitoring based on inter-continental stereoscopic detections |
recent advances in space technologies cause significant increase in satellite launches in next decade. it is expected that hundreds of satellites to be launched into orbit every year. current operations of the satellites struggle with keeping their satellites in safe condition (free of collision risks). in near future,... | general collision avoidance maneuver decision algorithm |
this paper lies in the framework of mission scenarios, such as active debris removal and on-orbit servicing, which require an active spacecraft (chaser) to orbit in close-proximity with respect to a space target. specifically, these activities involve relative orbital maneuvers, such as monitoring, rendezvous and docki... | safe trajectory design and pose estimation for target monitoring in geo |
the deployment of mega constellations has had a significant effect on the compounding space debris environment, increasing the number of on-orbit objects in all conditions and damaging the stability of the space debris environment. the increased density of space objects is associated with an increased risk of on-orbit ... | self-induced collision risk of the starlink constellation based on long-term orbital evolution analysis |
canada was an early adopter of methane regulation in the oil and gas sector, and recently announced a more ambitious goal to reduce 75% of methane emissions by 2030. new stricter methane regulations should also help reduce loading of air pollutants typically associated with methane emissions (h2s, vocs, ozone). to exam... | underestimation of reported methane emissions, and air pollutant loadings, from upstream oil and gas activities in canada |
canada is a signatory to the global methane pledge and is aiming to achieve a 75% cut in methane from 2030 levels from oil and gas production through regulatory updates and a 50% cut in waste sector emissions using new regulations. despite numerous large-scale studies that have measured and identified emission sources ... | a comparison of methane source localization methods in landfills across canada using truck-based measurement, lagrangian stochastic back trajectory modeling, and landsat thermal images |
at present, governments around the world and the organization are demonstrating how to deploy leo communication constellations, such as starlink, space-based information network and other mega constellations. with the satellite increasing quantity, it greatly increases the risk of satellite in orbit collision. in case ... | research on the autonomous avoidance technology of satellite applicable to the low-orbit giant constellations |
the intensive use of near-earth space and the lack of disposal measures for space objects of various purposes (spacecraft, launch vehicle stages, upper stages, upper stages, etc.) resulted in the formation of what is called debris, in this case space debris. part of the space debris is observed and registered, these ar... | analysis of empirical dependencies to calculate the crater diameter produced by the collision of a spacecraft with a space debris fragment |
we present results on the shape of bennu, using newly acquired data by the osiris-rex mission. | investigating the shape of bennu |
reducing fugitive methane emissions has become a focus area in many jurisdictions looking to curb greenhouse gas emissions. continued drilling combined with aging oil and gas infrastructure suggests occurrences of fugitive methane emissions due to gas migration (a type of wellbore instability) are likely to increase. p... | surface-based soil gas flux measurements are a more reliable tool than in-soil gas concentrations for detecting gas migration |
the mackenzie-beaufort delta (mbd) in northern canada is an area rich in hydrocarbon deposits, with known natural geologic methane seeps that are aided by permafrost heterogeneity. a recent airborne eddy covariance study found hotspots of activity in which methane was moderately elevated and presumed to be geologic in ... | landscape-scale variability of methane in the mackenzie-beaufort delta region of northern canada, during winter and summer. |
we consider calculation of capital requirements when the underlying economic scenarios are determined by simulatable risk factors. in the respective nested simulation framework, the goal is to estimate portfolio tail risk, quantified via var or tvar of a given collection of future economic scenarios representing factor... | sequential design and spatial modeling for portfolio tail risk measurement |
a 2016 study produced an initial feasibility assessment of a system, called "necropolis", to collect uncontrolled satellites in geosynchronous orbit and re-locate them at a long-term storage facility, kept under permanent control. the study identified three areas that required attention in subsequent work. the first ar... | preserving geostationary orbit: the next steps |
the permafrost affected arctic-boreal region is increasingly vulnerable to soil thaw and warming, which can enhance root respiration and microbial mineralization. however, the seasonal patterns and magnitudes of belowground co2 emissions from boreal and tundra remain poorly understood. also uncertain is how feedbacks a... | soil co2 flux in the permafrost zone: new insight from a year-round chamber network in alaska and canada |
southeastern saskatchewan, canada contains a 10,000 km2 region heavily developed by oil and gas activity that has been struggling with air quality issues, arising from hundreds or thousands of oil and gas leak points. the region is also very diverse in terms of oilfield operators, who use extraction techniques includin... | mapping fugitive gas emission sources and severity across southeastern saskatchewan |
this paper investigates which debris are highly dangerous to exacerbate the future orbital environment based on the outcomes of an orbital debris evolutionary model with two different algorithms of collision risk assessment. one is "two-sphere overwrap" collision risk assessment, which focuses on the geometrical relati... | determination of harmful space debris using two collision calculation algorithms |
vehicle-based surveys using laser and other analyzers are now commonplace in research and industry. in many cases when these studies target biologically-relevant gases like methane and carbon dioxide, the minimum detection limits are often coarse (ppm) relative to the analyzer's capabilities (ppb), because of the inher... | timeseries signal processing for enhancing mobile surveys: learning from field studies |
fugitive gas, comprised primarily of methane, can be unintentionally released from upstream oil and gas development either at surface from leaky infrastructure or in the subsurface through failure of energy well bore integrity. for the latter, defective cement seals around energy well casings may permit buoyant flow of... | advancing knowledge on fugitive natural gas from energy resource development at a controlled release field observatory |
most of the cataloged objects in low earth orbits are space debris, considering that less than 7% are operational spacecraft. in this work, the orbital dynamics of spacedebris are studied in the neighborhood of the brazilian satellites, cbers and scd, and around of the iss - international space station. the resultsshow... | space debris in the neighborhood of the operational artificial satellites |
the evolution of the debris field generated by an onorbit explosion or collision fragmentation event is of critical concern to space operators and ssa organizations. the debris field can be initially generated by combining one of the available breakup models containing imparted velocity and fragment size probability de... | fragmentation event debris field evolution using 3d volumetric risk assessment |
in recent years several formulations of debris indices have been proposed to provide a fast assessment of the criticality of a space object in terms of its impact on the debris environment. in a previous work, we proposed a formulation (ecob, environmental consequences of orbital breakups) based on the evaluation of th... | extending the ecob space debris index with fragmentation risk estimation |
in this chapter, a method to assess the occurrence of impacts between objects (either spacecraft or space debris) orbiting around the earth is presented. the method is based on the computation of the minimum distance between two evolving orbits by means of a rigorous global optimizer. analytical solutions of artificial... | rigorous global optimization for collision risk assessment on perturbed orbits |
surface air temperatures in the arctic have been increasing twice as fast as the global average, and climate models project that this rate of warming will continue through the century, with the greatest warming occurring during the winter months. an increase in wintertime temperature may reduce belowground carbon stora... | co2 emissions from permafrost regions in alaska during the nongrowing seasons |
orbit lifetime prediction is an important component of satellite mission design and post-launch space operations. throughout its lifetime in space, a spacecraft is exposed to risk of collision with orbital debris or operational satellites. this risk is especially high within the low earth orbit (leo) region where the h... | effects of deorbitsail as applied to lifetime predictions of low earth orbit satellites |
if we are to attain the recent north american goals to reduce methane (ch4) emissions, we must understand emission patterns across developments of different types. in this study we quantified the incidence of ch4 emissions from unconventional natural gas infrastructure accessing the montney play in british columbia, ca... | methane emissions from hydraulically fractured natural gas developments in northeastern british columbia |
the marcellus shale energy and environment laboratory (mseel) in west virginia provides a unique opportunity in the field of unconventional energy research. by studying near-surface atmospheric chemistry over several phases of a hydraulic fracturing event, the project will help evaluate the impact of current practices,... | atmospheric gas concentrations in the pre- and post-production phases of an unconventional oil and gas recovery operation at the mseel test site, west virginia |
numerous parameter estimation techniques exist for characterizing the arterial system using electrical circuit analogs. however, they are often limited by their requirements and usually high computational burdain. therefore, a new method for estimating arterial parameters based on monte carlo simulation is proposed. a ... | time domain estimation of arterial parameters using the windkessel model and the monte carlo method |
in the harsh conditions of the antarctic dry valleys, microbial activity has been recorded via measurements of soil carbon dioxide (co2) concentration and surface efflux. however, high temporal resolution studies in the dry valleys have also shown that abiotic solubility-driven processes can strongly influence (and per... | role of biotic and abiotic processes on soil co2 dynamics in the mcmurdo dry valleys, antarctica |
concentrations of gases in the lower atmosphere are controlled by spatially and temporally heterogeneous factors such as air temperature, biological activity and degree of industrial development. seeing as how baseline concentrations are often required for studies of environmental change, we need a better understanding... | raw baseline concentrations and environmental controls on background co2 and ch4 for sites across canada |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.