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2016-03-01 | We investigate a two-level system in a cavity QED by considering the effects of amplitude damping, phase damping and driving field. We have studied the non-Markovianity in resonance and non-resonance limits in the presence of these effects using Breuer–Laine–Piilo (BLP) non-Markovianity measure ( N _BLP). The evolution of the system is derived using the time convolutionless (TCL) master equation. In some conditions, it is shown that in the presence of a driving field, the N _BLP increases in the resonance and non-resonance limits. We have also found the exact solution of the master equation in order to investigate the effect of temperature- and environment-excited states. We have shown that the behaviour of non-Markovianity is very different from what one can see from the TCL approach. We have also presented some explanation about the behaviour of non-Markovianity in the exact solution using quantum discord (QD). | Dynamics of non-Markovianity in the presence of a driving field | 10.1007/s12043-015-1039-z |
2016-03-01 | The damping characterization is important in making accurate predictions of the seismic response of the hybrid structures dominated by different damping mechanisms. Different damping characteristics arise from the construction of the tower with different materials: steel for the upper part; reinforced concrete for the lower main part and interaction with supporting soil. The process of modeling damping matrices and experimental verification is challenging because damping cannot be determined via static tests as mass and stiffness can be. The assumption of classical damping is not appropriate if the system to be analyzed consists of two or more parts with significantly different levels of damping. The dynamic response of structures is critically determined by the damping mechanisms, and its value is very important for the design and analysis of vibrating structures. An analytical approach that is capable of evaluating the equivalent modal damping ratio from structural components is desirable for improving seismic design. Two approaches are considered to define and investigate dynamic characteristics of a composite tower of cable-stayed bridges: The first approach makes use of a simplified approximation of two lumped masses to investigate the structure irregularity effects including damping of different material, mass ratio, frequency ratio on dynamic characteristics and modal damping. The second approach employs a detailed numerical step-by-step integration procedure. | Exploring damping characteristics of composite tower of cable-stayed bridges | 10.1007/s12046-016-0467-x |
2016-03-01 | The problem of damping motion of a hydromechanical system consisting of a viscous fluid and its bounding rigid walls is solved. A condition under which there is an abrupt deceleration of the hydromechanical system is determined. | Motion of a viscous fluid and a wall in the presence of a stationary wall | 10.1134/S0021894416020085 |
2016-03-01 | This paper analyzes the dynamical response of taut strings crossed by systems of traveling forces at constant velocity. Starting from the classic solution for the single moving load, the effect of trains of forces having a step equal to the string length is dealt with. The response is formulated in terms of a linear map, whose reiteration furnishes the discrete-time response, and enables the investigation of the asymptotic behavior of the system. The analytical solution highlights the presence of many critical velocities, for which an instability phenomenon by response accretion may occur. The presence of damping inhibits the onset of instability but also allows to attain large displacements, especially in correspondence of the first critical velocities of the undamped string. Finite-difference numerical solutions confirm the full validity of the proposed analytical solutions. A simple procedure to deduce an improved solution for the problem of the single moving force is outlined in the Appendix. | Dynamics of taut strings traveled by train of forces | 10.1007/s00161-015-0473-y |
2016-03-01 | Thermoelastic damping is a significant energy lost mechanism at room temperature in micro-scale resonators. Prediction of thermoelastic damping (TED) is crucial in the design of high quality MEMS resonators. In this study the governing equations of motion and the thermal couple equation of a microplate with an arbitrary rectangular shape are derived using the modified version of the couple stress theory. Analytical expressions are presented for calculating the quality factor (QF) of TED in a rectangular microplate considering the plane stress and plane strain conditions. As a case study, a rectangular microplate resonator is considered with material property of gold that has a considerably high value of length-scale parameter in comparison with silicon and the effect of the length-scale parameter on the QF of TED is discussed in detail. The relation between QF and temperature increment for microplates with clamped boundary conditions based on plane stress and plane strain models are studied and results obtained by considering classical and modified couple stress theory (MCST) are compared. The effect of thickness of the plate on the rigidity ratio is studied and the critical thickness which is an important design parameter is obtained using the MCST for three boundary conditions. Variations of TED versus the plate thickness for various boundary conditions according to the classical and the modified couple stress theories are investigated. | Investigation of thermoelastic damping in rectangular microplate resonator using modified couple stress theory | 10.1007/s10999-014-9286-6 |
2016-03-01 | Numerical methods for solving linearly damped Hamiltonian systems are constructed using the popular Störmer–Verlet and implicit midpoint methods. Each method is shown to preserve dissipation of symplecticity and dissipation of angular momentum of an N -body system with pairwise distance dependent interactions. Necessary and sufficient conditions for second order accuracy are derived. Analysis for linear equations gives explicit relationships between the damping parameter and the step size to reveal when the methods are most advantageous; essentially, the damping rate of the numerical solution is exactly preserved under these conditions. The methods are applied to several model problems, both ODEs and PDEs. Additional structure preservation is discovered for the discretized PDEs, in one case dissipation in total linear momentum and in another dissipation in mass are preserved by the methods. The numerical results, along with comparisons to standard Runge–Kutta methods and another structure-preserving method, demonstrate the usefulness and strengths of the methods. | Second Order Conformal Symplectic Schemes for Damped Hamiltonian Systems | 10.1007/s10915-015-0062-z |
2016-03-01 | Dynamic stability of cutting processes against chatter vibration is a key requirement for high-speed machining and high material removal rate with high-quality surface finish. In the present work, the stiffness and damping of the machine tool are varied semi-actively by means of a magnetorheological (MR) damper to suppress chatter. An integrated mechatronic model is presented for the chatter analysis of a machine tool equipped with MR damper. Since the structure becomes nonlinear in the presence of MR damper, a novel chatter detection index (CDI) is developed to detect chatter from time-domain vibration signals. Subsequently, a fuzzy controller is designed to compute the best supply voltage to MR damper based on the measured vibration signals. The obtained results from the numerical analysis of the integrated model are encouraging, demonstrating a significant improvement in the dynamic stability of machining process, as well as the ability of detecting and suppressing chatter. | Semi-active fuzzy control of machine tool chatter vibration using smart MR dampers | 10.1007/s00170-015-7503-6 |
2016-03-01 | Hanged cables of through and half-through arch bridges are vulnerable to dynamic excitation because their intrinsic damping is very low. These components have been exhibiting unanticipated and excessive vibrations, which require more frequent maintenance and affect normal operations of the entire arch bridge. Mitigation of cable vibrations is commonly addressed by using an external damper attached to the cable. In this paper, the vibrations of hanged cables controlled by the viscous damper system was studied in detail using an analytical formulation of the complex eigenvalue problem. Oscillation parameters of the hanged cable-damper systems were analyzed by the exact values of complex eigenvalue. As a result, optimal parameters of the viscous damper could be evaluated and selected in order to reduce vibrations of cable. In addition, a design example was presented to justify the methodology. | Optimal parameters of viscous damper for hanged cables in arch bridges | 10.1007/s12205-015-0771-8 |
2016-03-01 | The mechanical properties and phase morphology of a nanocomposite plate made from sulphonated poly (ether ether ketone) and p-toluene sulphonic acid-doped polyaniline nanoparticles were investigated. To study the static and dynamic response of the plate to transverse loads, the method of multiquadric radial basis functions is developed. The numerical results obtained are compared with those found by other analytical methods. | Analysis of High-Performance PTSA-DOPED Polyaniline-Speek Nanocomposites | 10.1007/s11029-016-9563-6 |
2016-03-01 | The wide deployment of wind turbines in locations with high seismic hazard has led engineers to take into account a more comprehensive seismic design of such structures. Turbine specific guidelines usually use simplified methods and consider many assumptions to combine seismic demand with the other operational loads effecting the design of these structures. As the turbines increase in size and capacity, the interaction between seismic loads and aerodynamic loads becomes even more important. In response to the need for a computational tool that can perform coupled simulations of wind and seismic loads, a seismic module is developed for the FAST code and described in this research. This platform allows engineers working in this industry to directly consider interaction between seismic and other environmental loads for turbines. This paper details the practical application and theory of this platform and provides examples for the use of different capabilities. The platform is then used to show the suitable earthquake and operational load combination with the implicit consideration of aerodynamic damping by estimating appropriate load factors. | A computational platform for considering the effects of aerodynamic and seismic load combination for utility scale horizontal axis wind turbines | 10.1007/s11803-016-0307-3 |
2016-03-01 | The motion of collisional plasmas can be governed either by the Euler-Maxwell system with damping at the fluid level or by the Vlasov-Maxwell-Boltzmann system at the kinetic level. In the note, we present some recent results in [8] and [7] for the study of the non-trivial large-time behavior of solutions to the Cauchy problem on the related models in perturbation framework. | Large-time behavior for fluid and kinetic plasmas with collisions | 10.1007/s00574-016-0140-3 |
2016-03-01 | Falling Weight Deflectometer (FWD) produces pavement responses using a falling mass drop. This study investigated the features involved in the finite element modeling of FWD tests to help in the calibration of backcalculation. Falling mass, model size, subgrade damping, and boundary conditions were studied to reveal the significances of these factors on pavement responses. By modeling the falling mass in finite element models, this study has justified the idea that field-measured time history of impact force can be used as an alternative to falling mass. It is also concluded that subgrade damping, self-weight of slab, and boundary conditions are significant in modeling and interpretation of FWD finite element analysis. Finite element model with at least six times radius of relative stiffness is required to simulate dynamic responses of a continuously reinforced concrete slab. | Issues in simulating falling weight deflectometer test on concrete pavements | 10.1007/s12205-015-0299-y |
2016-03-01 | A hybrid joint interface module (HJIM) was developed using viscoelastic materials’ (VEM) “incompressible” property. The HJIM composes VEM layers compressed by screws. Its static stiffness and damping had been characterized by inverse receptance method. The analysis result showed that its static stiffness increases by nearly 50 % with increasing compression preload without compromising its loss factor. A comparison study of HJIM with a viscoelastic material joint interface module (VJIM) revealed that the change of the screws mechanical contact conditions affected the HJIM’s stiffness. Compression preload by fastening the screws, however, did not significantly affect the damping property of the HJIM. On the contrary to shear pre-strain, compression preload did not affect the VEM’s properties shown by studying the VJIM case. A workpiece was studied while fixed on the HJIM. Varying compression preload affected the stiffness of HJIM and that resulted in increased shear strain in VEM for certain modes while decreased shear strain in VEM for other modes. The affected shear strain in VEM altered the vibrational strain energy distribution and changed the receptance amplitude of different modes. In addition to apply the VEM where it is significantly strained, the analysis revealed that constraining the shear strain in VEM resulted in reduced receptance amplitude for different modes. The changes of receptance will further affect the vibration conditions in machining. | Constraining the shear strain in viscoelastic materials and utlization of the “incompressible” properties for damping treatment in hybrid joint interface module to improve their effect for vibration control in machining | 10.1007/s00170-015-7487-2 |
2016-03-01 | It is analytically difficult to calculate roll damping of ships due to the effects of viscosity. Therefore, computational fluid dynamics (CFD) has become a powerful tool in predicting roll damping recently. The unsteady flow around a forced rolling hull section with bilge keels can be calculated using a commercial URANS code which includes the viscous effects. In this study, two-dimensional (2D) roll damping calculations for a S60 midsection with bilge keels including free surface effects are performed for shallow draft case. The first objective of the study is to show whether the URANS code can be used to predict roll damping coefficient correctly. The second one is to show why Ikeda’s estimation method is insufficient at shallow draft case. Sinusoidal forced roll motion calculation method of roll damping moment with the help of a sliding interface and a fixed roll axis is successfully applied to predict roll damping coefficient. The calculations are carried out for different roll motion periods and amplitudes to validate the accuracy of the URANS code for different cases. Numerical results are compared with experiments, which were carried out at the towing tank facility of Osaka Prefecture University (OPU), and Ikeda’s estimation method. The results show that the URANS code is capable of predicting roll damping coefficients in a good agreement with experimental results and can be used further to develop a better model for prediction of roll damping. | URANS prediction of roll damping for a ship hull section at shallow draft | 10.1007/s00773-015-0331-4 |
2016-03-01 | We demonstrate methods of enhancing robustness of entanglement of two-qubit systems undergoing generalized amplitude damping decoherence using weak measurement and measurement reversal. The results show that the local action of generalized amplitude damping noise can cause sudden death of entanglement, and the weak measurement and measurement reversal is useful for combating generalized amplitude damping decoherence and recovering the entanglement of two entangled qubits. In addition, the results indicate that it would be much more easily implemented by applying quantum measurement reversal on a single-qubit to enhance robustness of entanglement in finite temperature environment, than on both qubits. | Enhancing Robustness of Entanglement in Finite Temperature Environment Using Quantum Measurement Reversal | 10.1007/s10773-015-2781-1 |
2016-03-01 | A method for determining the drag coefficient of a thin plate harmonically oscillating in a viscous incompressible fluid is proposed. The method is based on measuring the amplitude of deflections of cantilever-fixed thin plates exhibiting damping flexural oscillations with a frequency corresponding to the first mode and on solving an inverse problem of calculating the drag coefficient on the basis of the experimentally found logarithmic decrement of beam oscillations. | Theoretical-experimental method of determining the drag coefficient of a harmonically oscillating thin plate | 10.1134/S0021894416020103 |
2016-03-01 | We studied a mold oscillating mechanism for continuous casting. An equivalent hydraulic servo system model was established including a non-linear property and line volume near the hydraulic cylinder. The analysis focused on a practical behavior of the system. To observe an oscillated object and dynamic responses, an equivalent stiffness, damping ratio and simple mass-damper-spring 1-DOF model were established by Karl-Erik Rydberg’s research, and showed hydraulic cylinder pressure and line volume near the hydraulic cylinder. Especially, hydraulic pressure including statue of a mechanical and hydraulic cylinder was analyzed in the time and frequency domain. The results were validated by comparing responses between the 1-DOF model and the nonlinear hydraulic servo system model. The line volume that connects the hydraulic cylinder and the hydraulic servo valve has great effect on damping ratio and natural frequency of the hydraulic servo system. When the line pipe has high volume compared to normal statue, the hydraulic cylinder pressure has sharp peak frequencies that are located on natural frequency and its duple-harmonic terms with sideband peaks; (±2×exciting frequency) space. Based on this fact, we investigated the model using sensitivity analysis, and explained an oscillating mechanism about the mold oscillator by applying additional spring. A design of robust control for the mold oscillator was suggested by Negative strip time criterion, and maximum additional spring stiffness was shown. | Practical behavior of advanced non-linear hydraulic servo system model for a mold oscillating mechanism depending on line volume | 10.1007/s12206-016-0201-y |
2016-03-01 | Frequency-domain airborne electromagnetics is a proven geophysical exploration method. Presently, the interpretation is mainly based on resistivity—depth imaging and one-dimensional layered inversion; nevertheless, it is difficult to obtain satisfactory results for two- or three-dimensional complex earth structures using 1D methods. 3D forward modeling and inversion can be used but are hampered by computational limitations because of the large number of data. Thus, we developed a 2.5D frequency-domain airborne electromagnetic forward modeling and inversion algorithm. To eliminate the source singularities in the numerical simulations, we split the fields into primary and secondary fields. The primary fields are calculated using homogeneous or layered models with analytical solutions, and the secondary (scattered) fields are solved by the finite-element method. The linear system of equations is solved by using the large-scale sparse matrix parallel direct solver, which greatly improves the computational efficiency. The inversion algorithm was based on damping least-squares and singular value decomposition and combined the pseudo forward modeling and reciprocity principle to compute the Jacobian matrix. Synthetic and field data were used to test the effectiveness of the proposed method. | 2.5D forward modeling and inversion of frequency-domain airborne electromagnetic data | 10.1007/s11770-016-0548-y |
2016-02-27 | Background The N -dimensional isentropic compressible Euler system with a damping term is one of the most fundamental equations in fluid dynamics. Since it does not have a general solution in a closed form for arbitrary well-posed initial value problems. Constructing exact solutions to the system is a useful way to obtain important information on the properties of its solutions. Method In this article, we construct two families of exact solutions for the one-dimensional isentropic compressible Euler equations with damping by the perturbational method. The two families of exact solutions found include the cases $$\gamma >1$$ γ > 1 and $$\gamma =1$$ γ = 1 , where $$\gamma$$ γ is the adiabatic constant. Results With analysis of the key ordinary differential equation, we show that the classes of solutions include both blowup type and global existence type when the parameters are suitably chosen. Moreover, in the blowup cases, we show that the singularities are of essential type in the sense that they cannot be smoothed by redefining values at the odd points. Conclusion The two families of exact solutions obtained in this paper can be useful to study of related numerical methods and algorithms such as the finite difference method, the finite element method and the finite volume method that are applied by scientists to simulate the fluids for applications. | Perturbational blowup solutions to the compressible Euler equations with damping | 10.1186/s40064-016-1766-8 |
2016-02-06 | We establish a Philos-type oscillation theorem for a class of nonlinear second-order neutral delay dynamic equations with damping on a time scale by using the Riccati transformation and integral averaging technique. An illustrative example is provided to show that our theorem has practicability and maneuverability. | A Philos-type theorem for second-order neutral delay dynamic equations with damping | 10.1186/s13662-016-0767-9 |
2016-02-01 | Rubbers are commonly used in industry to reduce vibration transfer and, consequently, reduce structural noise. The vibration transfer through rubber can be modelled with finite elements; however, to achieve satisfactory results it is necessary to know the viscoelastic properties of the rubber. This paper describes the commonly used theory of vibration transmission through rubber modelled as a single-degree-of-freedom (SDOF) system. Three simplified rubber models are used to identify the constant Young’s modulus and damping factor from the measurements of two different rubber specimens, and with the obtained results the theoretical transmissibilities are calculated. The frequency-dependent Young’s modulus and damping factor are also calculated from measurements. The practical use of previous measurements of dynamic material properties is presented in a finite-element analysis, where three different definitions of the dynamic material properties are carried out for four different rubber specimens, which corresponds to 12 analyses. The finite-element analyses are then compared with the measurements, and general guidelines for using dynamic material properties in ANSYS Workbench v.14 are given. | Evaluation of the Frequency-Dependent Young’s Modulus and Damping Factor of Rubber from Experiment and Their Implementation in a Finite-Element Analysis | 10.1007/s40799-016-0027-7 |
2016-02-01 | In the current research, the muscle equivalent linear damping coefficient which is introduced as the force–velocity relation in a muscle model and the corresponding time constant are investigated. In order to reach this goal, a 1D skeletal muscle model was used. Two characterizations of this model using a linear force–stiffness relationship (Hill-type model) and a nonlinear one have been implemented. The OpenSim platform was used for verification of the model. The isometric activation has been used for the simulation. The equivalent linear damping and the time constant of each model were extracted by using the results obtained from the simulation. The results provide a better insight into the characteristics of each model. It is found that the nonlinear models had a response rate closer to the reality compared to the Hill-type models. | Equivalent linear damping characterization in linear and nonlinear force–stiffness muscle models | 10.1007/s00422-016-0680-z |
2016-02-01 | A theoretical scheme is proposed to implement bidirectional quantum controlled teleportation (BQCT) by using a nine-qubit entangled state as a quantum channel, where Alice may transmit an arbitrary two-qubit state called qubits $$A_1$$ A 1 and $$A_2$$ A 2 to Bob; and at the same time, Bob may also transmit an arbitrary two-qubit state called qubits $$B_1$$ B 1 and $$B_2$$ B 2 to Alice via the control of the supervisor Charlie. Based on our channel, we explicitly show how the bidirectional quantum controlled teleportation protocol works. And we show this bidirectional quantum controlled teleportation scheme may be determinate and secure. Taking the amplitude-damping noise and the phase-damping noise as typical noisy channels, we analytically derive the fidelities of the BQCT process and show that the fidelities in these two cases only depend on the amplitude parameter of the initial state and the decoherence noisy rate. | Bidirectional controlled teleportation by using nine-qubit entangled state in noisy environments | 10.1007/s11128-015-1194-7 |
2016-02-01 | We study the kinetic Kuramoto model for coupled oscillators with coupling constant below the synchronization threshold. We manage to prove that, for any analytic initial datum, if the interaction is small enough, the order parameter of the model vanishes exponentially fast, and the solution is asymptotically described by a free flow. This behavior is similar to the phenomenon of Landau damping in plasma physics. In the proof we use a combination of techniques from Landau damping and from abstract Cauchy–Kowalewskaya theorem. | Exponential Dephasing of Oscillators in the Kinetic Kuramoto Model | 10.1007/s10955-015-1426-3 |
2016-02-01 | In the present study, forced vibration of an oscillator equipped with the tuned mass damper and the impact damper is investigated. In the impact damper system, elastic contact between masses is described using the Hertzian contact model and the energy loss during each contact is considered using a viscous damper. Application of the conventional impact dampers for suppressing forced vibrations is studied with changing the mass ratio and restitution coefficient. Furthermore, variable coefficient of restitution impact dampers are used to attenuate forced vibration. To improve application of the conventional impact dampers, the barriers of these systems are equipped with the MR fluid dampers, and for convenience, this kind of impact dampers is simply named as smart impact dampers. Effect of changing the input electrical current and contact speed is studied on application of the smart impact dampers. Finally, it is shown that the smart impact dampers can suppress undesired forced vibrations stronger than their equivalent impact dampers and tuned mass dampers. | Suppressing forced vibrations of structures using smart vibro-impact systems | 10.1007/s11071-015-2437-y |
2016-02-01 | The classical theory of mass-spring-damper-type dynamical systems on the ordinary flat space ℝ^3 may be generalized to higher-dimensional Riemannian manifolds by reformulating the basic underlying physical principles through differential geometry. Nonlinear dynamical systems have been studied in the scientific literature because they arise naturally from the modeling of complex physical structures and because such dynamical systems constitute the basis for several modern applications such as the secure transmission of information. The flows of nonlinear dynamical systems may evolve over time in complex, non-repeating (although deterministic) patterns. The focus of the present paper is on formulating the general equations that describe the dynamics of a point-wise particle sliding on a Riemannian manifold in a coordinate-free manner. The paper shows how the equations particularize in the case of some manifolds of interest in the scientific literature, such as the Stiefel manifold and the manifold of symmetric positive-definite matrices. | Nonlinear damped oscillators on Riemannian manifolds: Fundamentals | 10.1007/s11424-015-4063-7 |
2016-02-01 | A mechanically resonant torsional spring scanner was previously designed for light dispersion application. However, the effects of mountings and pressure variation on the damping characteristic of the scanner were not well studied. In this study, the damping characteristics of the linear optical scanner with torsional spring mechanism are investigated with a mathematical model and various experiments. To examine the scanner’s free response profile when the resonance frequency and damping ratio were varied, a damping model was established based on experimental results. Several experiments were performed to investigate the damping characteristics when environmental pressure and scanner mounting are changed. The scanner mountings consist of rigid mounting, spring demounting, and the use of various dampers. In general, the scanner damping was shown to be greater at higher atmospheric pressures when the scanner was mounted on a foam damper. | An Investigation on the Damping Characteristics of a Linear Optical Scanner | 10.1007/s40799-016-0032-x |
2016-02-01 | A simple and practical multiscale approach suitable for topology optimization of structural damping in a component ready for additive manufacturing is presented. The approach consists of two steps: First, the homogenized loss factor of a two-phase material is maximized. This is done in order to obtain a range of isotropic microstructures that have a connected stiff material phase. Second, the structural damping of the component is maximized using material interpolations based on the homogenized properties of the microstructures. In order to achieve convergence towards a discrete set of material phases in the macroscopic problem, a material interpolation that favors values close to the predefined material densities is introduced. | A practical multiscale approach for optimization of structural damping | 10.1007/s00158-015-1326-9 |
2016-02-01 | The Mg alloy composite foams reinforced by SiC particles were fabricated by the melt foaming route. The composite foams exhibit uniform cell structure with a size of 0.6-0.8 mm and SiC_p distribution. The compressive behavior and damping property of the composite foams were emphasized. It is shown that the yield stress and the plateau stress depend on both porosity and SiC_p content of the composite foam, which decrease with the increasing porosity, while sharper fluctuation of flow stress in the plateau region appears under the higher SiC_p content. Meanwhile, the SiC_p addition elevates the ideal energy absorption efficiency of the Mg alloy foams, but decreases the total amount of energy absorption. Furthermore, the loss factor β is essentially independent of temperature below approximately 250 °C, then increases rapidly with the increasing temperature. It is concluded that the composite foams show typical brittle characteristic and better damping property compared to Mg alloy foams for the SiC_p addition. The improvement is attributed to the increasing interfacial microslip and microplasticity deformation derived from the micro-crack between the SiC_p-Mg alloy interfaces. | Compressive Behavior and Damping Property of Mg Alloy/SiC_p Composite Foams | 10.1007/s11665-015-1878-2 |
2016-02-01 | An analytical approach is presented to investigate the optimal problem of non-traditional type of Dynamic vibration absorber (DVA) for damped primary structures subjected to ground motion. Different from the standard configuration, the non-traditional DVA contains a linear viscous damper connecting the absorber mass directly to the ground instead of the main mass. There have been many studies on the design of the non-traditional DVA for undamped primary structures. Those studies have shown that the non-traditional DVA produces better performance than the standard DVA does. When damping is present at the primary system, there are very few works on the non-traditional dynamic vibration absorber. To the best of our knowledge, there is no study on the design of non-traditional DVA for damped structures under ground motion. We propose a simple method to determine the approximate analytical solutions of the nontraditional DVA when the damped primary structure is subjected to ground motion. The main idea of the study is based on the criterion of the equivalent linearization method to replace approximately the original damped structure by an equivalent undamped one. Then the approximate analytical solution of the DVA’s parameters is given by using known results for the undamped structure obtained. Comparisons have been done to validate the effectiveness of the obtained results. | Research on the design of non-traditional dynamic vibration absorber for damped structures under ground motion | 10.1007/s12206-016-0113-x |
2016-02-01 | In this paper an energy generated mono tube MR damper model has been developed for vehicle suspension systems. A 3D model of energy generated MR damper is developed in Solid Works electromagnetic simulator (EMS) where it is analyzed extensively by finite element method. This dynamic simulation clearly illustrates the power generation ability of the damper. Two magnetic fields are induced inside this damper. One is in the outer coil of the power generator and another is in the piston head coils. The complete magnetic isolation between these two fields is accomplished here, which can be seen in the finite element analysis. The induced magnetic flux densities, magnetic field intensities of this damper are analyzed for characterizing the damper’s power generation ability. Finally, the proposed MR damper’s energy generation ability was studied experimentally. | Design and modeling of energy generated magneto rheological damper | 10.1007/s13367-016-0007-6 |
2016-01-21 | This paper presents a study on the damping ratio $$({\upbeta })$$ ( β ) used in discrete element simulations. Physical experiments are performed by dropping particles from a predetermined height. Two kinds of granular particles, aluminum and steel spheres, are used. The size of these particles are the same. The process of particle depositing under gravity is simulated using the discrete element method. The experimental observation is compared with the numerical result to identify the appropriate $${\upbeta }$$ β . The result indicates that the appropriate damping ratio used in discrete element simulations is between 0.2 and 0.3 %. Various $${\upbeta }$$ β are then used in the numerical simulations to study the effect of $${\upbeta }$$ β on the dropping process. The final height of the sample relates to $${\upbeta }$$ β and the drop height. The effect of $${\upbeta }$$ β is more profound for small drop height. For greater drop height, the effect of $${\upbeta }$$ β is negligible. | Numerical and experimental verification of a damping model used in DEM | 10.1007/s10035-015-0597-6 |
2016-01-01 | This chapter examines the dissipation of sound and vibration into heat, which, in turn, yields a damping of the amplitudes. One consequence of dissipation is that the quality factors of the resonances decrease. This decrease usually depends on frequency. In addition, dissipative phenomena are likely to modify the nature of the modes, which can become a combination of traveling and standing waves, called complex modes. This happens if the internal damping is said to be “non-proportional,” i.e., when the damping coefficients depend on space. It also occurs as a consequence of acoustic radiation into an “infinite” space, outside the instruments. Various causes of dissipation are examined in solid materials and in air. In solid materials, thermoelasticity and viscoelasticity are the main mechanisms of internal damping mechanisms. In some situations, air viscosity should also be considered as a pertinent cause of energy loss, as in the case of thin strings. In wind instruments, heat diffusion and viscosity are the main causes of damping. They appear near the walls of a tube. The theory of Kirchhoff, following that of Stokes and simplified by Zwikker and Kosten, is particularly relevant for describing these phenomena. | Dissipation and Damping | 10.1007/978-1-4939-3679-3_5 |
2016-01-01 | Levitation using superconducting magnets has come a long way since Arkadiev’s experiment in the early 1940s, resulting in the superconducting maglev system L0 series for the route between Tokyo and Osaka at 505 km/h. Recently, several prototypes were built to transfer semiconductors using superconducting magnets in a clean environment. With advances in high-temperature superconducting materials with more manageable proportions, this type of levitation is becoming worthy of further consideration. The three methods for levitation, based on diamagnetism, flux pinning effects and inductive systems, are outlined with their respectively associated applications. | Superconducting Magnet | 10.1007/978-94-017-7524-3_4 |
2016-01-01 | In seismic design, buildings are designed to respond to strong earthquake ground motions inelastically. The engineering norm followed in design and analysis is to use constant modal viscous damping ratios to account for all energy dissipation aside from that arising from material nonlinearity. In general, equivalent linear models, which aim to capture primarily the peak response with typically 2–5 % of critical damping are employed. In this paper, we show that the effective viscous damping ratio can be estimated from the dynamic response of actual building structural systems without linearization of the load-deformation characteristics. The empirical method we present, which estimates the effective viscous damping ratios of buildings, has been applied to several laboratory specimens and actual buildings. We show that the effective viscous damping ratio in a low to mid-rise reinforced concrete (RC) building responding at its dominant mode (equivalent of fundamental mode in linear elastic systems) varies linearly with the effective period of its dominant mode. The practical use of the method is demonstrated using acceleration records obtained in two 9-story small-scale RC laboratory test specimens during a series of strong base motions. Fundamental mode envelopes of hysteretic responses, that is, the backbone curves for both structures are estimated by excluding higher mode effects from the measured responses. | Estimating Effective Viscous Damping and Restoring Force in Reinforced Concrete Buildings | 10.1007/978-3-319-29751-4_27 |
2016-01-01 | Section 10.1 describes Landau damping and cyclotron damping. Dielectric tensor of bi-Maxwellian hot plasma ( 10.59 ) and ( 10.60 ) are derived step by step in Sects. 10.2 – 10.5 . Section 10.6 explains mathematical property of plasma dispersion function $$Z_\mathrm{p}(\zeta )$$ Z p ( ζ ) . Dispersion relation of electrostatic wave in homogeneous and inhomogeneous plasma are derived in Sects. 10.7 and 10.8 respectively. | Waves in Hot Plasmas | 10.1007/978-3-662-49781-4_10 |
2016-01-01 | Steel–concrete hybrid systems are used in buildings, in which a steel structure has been placed on a concrete structure to make a lighter structure and have a faster construction. Dynamic analysis of hybrid structures is usually a complex procedure due to various dynamic characteristics of each part, i.e., stiffness, mass and especially damping. Dynamic response of hybrid structures has some complications. One of the reasons is the different stiffness of the two parts of structure and another reason is non-uniform distribution of materials and their different features such as damping in main modes of vibration. The available software is not able to calculate damping matrices and analyze these structures because the damping matrix of these irregular structures is non-classical. Also an equivalent damping should be devoted to the whole structure and using the available software. In the hybrid structures, one or more transitional storeys are used for better transition of lateral and gravity forces. In this study, an equation has been proposed to determine the equivalent uniform damping ratio for hybrid steel–concrete buildings with transitional storey(s). In the proposed method, the hybrid structure containing concrete, steel and transitional storeys appropriately substituted with 3-DOF structure. A wide range of eigenfrequency and mass ratios is examined for each ratio pair, and given the characteristics of the primary system, the complete 3-DOF structure can be formed. Equivalent uniform damping ratio is derived by means of a semi-empirical error minimization procedure. The multiple nonlinear regressions are used for determination of equations of modal damping ratios of hybrid buildings. | Uniform Damping Ratio For Non-Classically Damped Hybrid Steel Concrete Structures | 10.1007/s40999-016-0003-8 |
2016-01-01 | As HXD high-power AC electric locomotives and CRH (China Railways High-speed) electrical multiple units (EMUs) are put into operation in large scale in China, coupled oscillation between locomotives and traction power supply network is increasingly prominent and unfavorable for normal operations of railways and safety of equipment. Nowadays, oscillation between locomotives and traction power supply network is urgently needed to be solved. High-frequency resonance is almost solved; therefore, low-frequency oscillation becomes the focus and difficulty. In this article, the state equations of the AC electric locomotives and the traction power supply network system are converted to transfer functions, and then input admittance transfer functions of the AC electric locomotives and the traction power supply network system are obtained according to the relationship between each other. Through analysis and simulation tools, in frequency domain, qualitative analysis is carried out for four low-frequency oscillation factors including control parameters, line impedance, load, and the number of the locomotives, and frequency-domain analysis results are effectively verified through time-domain simulation. The cause that influences the low-frequency oscillation is found in the relationship among the four factors, and then, the principle of low-frequency oscillation between the AC electric locomotives and the traction power supply network is obtained. | The Cause Analysis for Low-Frequency Oscillation of AC Electric Locomotive and Traction Power Supply Network | 10.1007/978-3-662-49367-0_59 |
2016-01-01 | An investigation on the damping effects of different gas mediums in a capacitive MEMS accelerometer is carried out. Air, argon, carbon-dioxide, helium, hydrogen, nitrogen and oxygen are considered for the study. Detailed calculations of the temperature and pressure effects on the properties of various gases are first performed. An electrical equivalent circuit is developed for the accelerometer structure incorporating squeezed film effects. The equivalent circuit is used to determine the dynamic and frequency response of the accelerometer under different pressures at 300 K, for various gases. From the simulation, the system bandwidth, resonant frequency, rise time and settling time are evaluated. Further, for the structure under investigation, the static sensitivity of the displacement and capacitance were obtained as 17 nm g^−1 and 101 fF g^−1, which is constant for all gases. It is inferred that helium provides better damping at low pressures, compared to other gases. However, at higher pressures, all the gases are found to behave similarly. | Study of squeeze film damping characteristics under different gas mediums in a capacitive MEMS accelerometer | 10.1007/s40430-015-0316-6 |
2016-01-01 | A waveguide is a system, which by means of its boundaries contains and directs the flow of energy in a construction. One such system is a structural waveguide typical of a ship construction. Aircraft and certain train constructions are also built up of frames and plates. Parallel frames mounted to plate elements guide the propagation of waves in a direction of the frames. A sandwich or honeycomb plate forms another type of waveguide. The laminates coupled to a core contain the energy flow in the structure. A third type of a waveguide system is a cylinder. | Waveguides | 10.1007/978-3-662-47934-6_14 |
2016-01-01 | Over the last two decades, piezoelectric materials have been extensively used as components in active and passive structural vibration control solutions. The most frequent applications consider piezoceramic thin patches bonded to thin structures subjected to bending. For active vibration control solutions, the piezoceramic patches can be used as strain sensors and/or bending actuators when connected to properly designed signal conditioning, processing, and amplification. For passive vibration control solutions, they can be used as vibration dampers and/or absorbers when connected to properly designed electronic shunt circuits. The objective of this chapter is to present some examples of the use of piezoelectric materials, as distributed sensors and actuators, for the development and implementation of passive and active vibration control solutions. | Piezoelectric Structural Vibration Control | 10.1007/978-3-319-29982-2_12 |
2016-01-01 | This paper presents a novel switched damping method which is able to improve the operational bandwidth of a linear electromagnetic energy harvester. In this system, different damping coefficients, in which values are computed based on the adaptive percentage-varying factor, are electronically switched at different points within the predefined oscillating quadrants. An analytical model of the switching damping device is presented, and the predictive results indicate that a reasonable large range of frequency shifts can be achieved for the proposed output resistances. The outputs for a range of values of internal coil resistance and electromotive force (emf) constant are recorded, and for the proposed system, the frequency can be shifted up to range of +19.50 to −81.46 % away from the initial resonance. | Analytical Modeling for Switched Damping Electromagnetic Energy Harvester | 10.1007/978-3-319-30117-4_1 |
2016-01-01 | The paper at hand shows how structural damping and stiffness parameters in shrunk joints can be determined by a generic joint experiment. With thin layer elements these parameters from the joint experiment are coupled to the structures Finite Element Model. Equivalent modal damping factors can be determined by performing a complex numerical modal analysis, by which the stability of the rotor can be tested. The two disc rotor is examined as an application sample. This rotor consists of a shaft with two shrunk-on discs. With the above mentioned approach, and by considering structural damping added to material damping, the modal damping of the first torsional eigenfrequency is calculated and then compared to the results of an experimental modal analysis. The paper shows that the presented approach leads to a reliable approximation of the examined structure’s dissipation properties. It serves as a prediction tool for the response behavior of a turbo-generator. | Simulation of Rotor Damping Assembled by Disc Shrink Fits | 10.1007/978-3-319-30084-9_43 |
2016-01-01 | Damping properties of assembled structures are largely influenced by frictional damping between joint interfaces. Therefore, these effects must be considered during the modeling process. Applying thin-layer elements (TLEs) with a linear, orthotropic material model on mechanical interfaces to incorporate joint damping has shown good agreement with experimental modal analysis in previous work. In the TLE model, constant hysteretic damping is assumed. The damping and stiffness parameters for the TLEs are experimentally identified on an isolated lap joint. Imprecisions caused by model simplifications and parameter uncertainty are addressed by model updating or uncertainty analysis. This requires multiple evaluations of models that are equivalent in all respects but their TLE parameterization. In this work, a model reduction technique for the TLE modeling approach is presented which significantly reduces computational cost for the re-calculation of eigenvalues after joint parameters are changed. The reduction is based on an eigensensitivity analysis and results in a single, linear equation for each eigenvalue. The presented approach is applied to a model updating example. Here, the model reduction allows for a much larger number of design variables which means experimental data can be reproduced more accurately with a physically more meaningful model. | Reduced thin-layer elements for modeling the nonlinear transfer behavior of bolted joints of automotive engine structures | 10.1007/s00419-015-1109-1 |
2016-01-01 | Without loss of generality, it can be assumed that a shunt VSC is installed at a busbar between nodes 1 and 2 in an N-machine power system, as shown in Fig. 7.1 . The shunt VSC can be connected to an energy storage system ( ESS ESS ), a HVDC, or a static renewable power station, such as a photovoltaic (PV) or fuel cell (FC) power station. It can operate alone as a VSC-based FACTS device, STATCOM (see Sect. 4.1.1.1 ). | Multi-machine Power Systems Installed with VSC-Based Stabilizers | 10.1007/978-1-4899-7696-3_7 |
2016-01-01 | A novel analytic approximate technique, namely optimal variational method (OVM), is employed to propose an approach to solve some nonconservative nonlinear oscillators. Different from perturbation methods, the validity of the OVM is independent on whether or not there exist small physical parameters in the considered nonlinear equations. This procedure offers a promising approach by constructing a generalized Lagrangian and a generalized Hamiltonian for nonlinear oscillators. An excellent agreement has been found between the analytical results obtained by the proposed method and numerical integration results. | The Oscillator with Linear and Cubic Elastic Restoring Force and Quadratic Damping | 10.1007/978-3-319-42408-8_18 |
2016-01-01 | In this chapter, we present the development of the 5-mg suspended mirror driven by the quantum back-action larger than the thermal fluctuating force. The origin of quantum back-action is momentum transferred to the mirror by light upon its reflection. Concerning the coherent light, the photon number fluctuates according to a Poisson distribution, which caused the radiation pressure fluctuation, termed radiation pressure shot noise (RPSN). The pendulum mode excited by this force fluctuation was estimated to be larger than the thermal fluctuating force by a factor of $$1.4\pm 0.2$$ 1.4 ± 0.2 at 325 Hz. To explain our estimation based on the noise analysis, we also present the optical, the mechanical, and the optomechanical characterization of our system. The relevant publication is Phys. Rev. A 92 , 033825 (2015) [ 1 ]. | Experimental Results | 10.1007/978-4-431-55882-8_6 |
2016-01-01 | A human can perceive the hardness of an object by tapping its surface. We compared the ranked subjective hardness values and physical properties of objects, including their stiffness, viscosity, density, and Shore hardness, and the frequencies and time constants of the natural vibrations caused by tapping. The stiffness, frequency, and viscosity exhibited a relatively strong positive correlation with the perceived hardness. The results show that the viscosity influences the hardness perceived by tapping, as well as the stiffness, whereas the stiffness and elasticity are considered to be major factors in the hardness perceived by pinching or pushing. | What is the Hardness Perceived by Tapping? | 10.1007/978-3-319-42321-0_1 |
2016-01-01 | For damped acoustic metamaterials, a discrete model is proposed in the form of a periodic structure with cells of the simplest type. The effective parameters of the model are determined by criteria based on the equality of dispersion of waves. The general properties of the model are studied. An example of one negative type of metamaterials is presented. The model is useful for analyzing wave properties and creating metamaterials with given acoustic properties. | A discrete model of damped acoustic metamaterials | 10.1134/S1063771016010012 |
2016-01-01 | A fractional derivative Zener (FDZ) model connected in parallel with a linear viscous damper and a Coulomb friction slider is used to numerically simulate the mechanical behavior of a base isolated (BI) building tested under free vibration conditions in Solarino, Sicily. This hybrid BI system comprises high damping rubber bearings in combination with low friction sliding bearings. A comparison study of the present model with previous ones appearing in the literature, namely the bi-linear and the tri-linear models defined in the time domain, is carried out here. Furthermore, the linear viscoelastic solid, namely the classical Zener model, is also implemented and evaluated. The rheological models representing all the above BI systems are analyzed and, for the first time, the rheological formulation for the tri-linear model is presented. The present comparison study shows that the FDZ model is capable of describing the complex nonlinear response of BI systems. | A fractional derivative Zener model for the numerical simulation of base isolated structures | 10.1007/s10518-015-9801-7 |
2016-01-01 | This text deals with the determination of stiffness and damping parameters of a dynamic system. These parameters are determined mathematically from the amplitude-frequency characteristics. In practice, this method is applied to automobile seat, which is equipped with a system of air springs without dampers. | Identification of Parameters of Stiffness and Damping Based on the Amplitude Frequency Characteristics | 10.1007/978-3-319-22762-7_63 |
2016-01-01 | In this paper, experimental characterization studies conducted for a tuned vibration absorber is presented. The tuned vibration absorber has been particularly designed to reduce transverse resonant vibration response of a supported cylinder structure at its dominant two modes. Various testing configurations and techniques have been used such as transmissibility measurements, frequency response measurements, sweep sine testing, impact testing, and random testing. Different testing approaches were needed to explain the differences between actual TVA characteristics and the initial design objectives. Finally, structure and tuned vibration absorber are tested together to check the actual vibration reduction performance of the tuned vibration absorber. | Experimental Characterization of a Tuned Vibration Absorber | 10.1007/978-3-319-29859-7_18 |
2016-01-01 | In this paper, we consider the wave equation with both weak frictional damping and viscoelastic damping acting simultaneously and complementarily in the domain. We establish an explicit and general decay rate result, using some properties of the convex functions. Our result is obtained without imposing any restrictive growth assumption on the frictional damping term and strongly weakening the usual assumptions on the relaxation function. | Uniform Decay Rates for Viscoelastic Dissipative Systems | 10.1007/s10883-014-9256-1 |
2016-01-01 | This article presents the sensitivity analysis of the method for determination of mass, damping and stiffness coefficients using the impulse excitation technique for a rotor-bearing system. Such an experimental approach is an adequate tool for the estimation of 24 dynamic coefficients, that is 4 damping coefficients, 4 mass coefficients and 4 stiffness coefficients for each bearing. As yet, the literature is exclusive of any researches into the sensitivity of this experimental method itself. However, the influence of several parameters (e.g. supply pressure, bearing geometry, etc.) on the calculation results concerning bearing dynamic coefficients had already been examined in detail. The preparation of the numerical model of the rotor made it possible to assess how influential are the input parameters—such as position and angle of an excitation force or movements of the sensor heads used to measure the displacements of bearing journals—to the results. The potential impact of changing parameters, such as stiffness of rotor material, its unbalance or its geometry, on the values of calculated stiffness, damping and mass coefficients in tested rotor-bearing system was also verified. The paper presents the calculation results of dynamic coefficients for the bearings along with their relative errors. It was shown how the calculated values change according to the different input parameters. The excitation signals and the corresponding system responses were also provided. Moreover, the article contains information on how to enhance the accuracy of calculations. | The Sensitivity Analysis of the Method for Identification of Bearing Dynamic Coefficients | 10.1007/978-3-319-42402-6_8 |
2016-01-01 | A rod-shape finite element with twelve degrees of freedom is proposed for modeling the elastic and damping properties of rotor blades with regard to their geometric stiffness caused by rotation of the rotor. A model of coupling of the torsion bar with blades is developed based on the hypothesis of linear deplanation of the connecting section of the torsion bar and a special transition element to ensure the compatibility of displacements of the torsion bar and blades upon their vibrations in the flapping and rotation planes. Numerical experiments were carried out to test and assess the validity of the model developed. Suggestions are made for ensuring unconditional stability of the iteration method in a subspace in determining the specified number of modes and frequencies of free vibrations of the torsion bar-blade structure. | Modeling the Elastic and Damping Properties of the Multilayered Torsion Bar-Blade Structure of Rotors of Light Helicopters of the New Generation 2. Finite-Element Approximation of Blades and a Model of Coupling of the Torsion Bar with the Blades | 10.1007/s11029-016-9548-5 |
2016-01-01 | In this paper, we mainly focus our attention on the global dynamical behaviour of some ubiquitous nonlinear oscillators under the presence of nonlinear dissipation. We particularly consider the parametrically driven Duffing oscillator and externally driven Helmholtz–Duffing oscillators with nonlinear dissipation term proportional to the power of velocity $$(v\left| v \right| ^{p-1})$$ ( v v p - 1 ) . We obtain the threshold condition for the occurrence of chaos analytically as well as numerically for all the cases $$p=$$ p = 1, 2, 3 and 4. We also identify the regions of 2D parameter space (consisting of external forcing amplitude and damping coefficient) corresponding to various asymptotic dynamics and analyse the effect of nonlinear damping on the overall dynamical behaviour of these nonlinear oscillators. | Dynamical behaviour of parametrically driven Duffing and externally driven Helmholtz–Duffing oscillators under nonlinear dissipation | 10.1007/s11071-015-2334-4 |
2016-01-01 | We turn now to a description of the basic techniques used for iteratively solving unconstrained minimization problems. These techniques are, of course, important for practical application since they often offer the simplest, most direct alternatives for obtaining solutions; but perhaps their greatest importance is that they establish certain reference plateaus with respect to difficulty of implementation and speed of convergence. Thus in later chapters as more efficient techniques and techniques capable of handling constraints are developed, reference is continually made to the basic techniques of this chapter both for guidance and as points of comparison. | Basic Descent Methods | 10.1007/978-3-319-18842-3_8 |
2016-01-01 | This paper firstly presents an equivalent coupling circuit modeling of multi-parallel inverters in microgrid operating in grid-connected mode. By using the model, the coupling resonance phenomena are explicitly investigated through the mathematical approach, and the intrinsic and extrinsic resonances exist widely in microgrid. Considering the inverter own reference current, other inverters reference current, and grid harmonic voltage, the distributions of resonance peaks with the growth in the number of inverters are obtained. Then, an active damping control parameter design method is proposed to attenuate coupling resonance, and the most salient feature is that the optimal range of the damping parameter can be easily located through an initiatively graphic method. Finally, simulations and experiments verify the validity of the proposed modeling and method. | Generalized coupling resonance modeling, analysis, and active damping of multi-parallel inverters in microgrid operating in grid-connected mode | 10.1007/s40565-016-0184-9 |
2016-01-01 | Damping vibrations occurring within the car’s suspension is an indispensable phenomenon in suspension operation. The most common damping element used in the suspension is the hydraulic shock absorber. Modern shock absorbers used in the suspensions mostly have nonlinear characteristics and other complex functional properties. The chapter presents research on hydraulic shock absorbers for similar conditions of their operation. The main aim of the study is to determine the forces generated in the damper due to the impact of road roughness. Thus the simulation studies were carried out on a developed dynamic model of the damper. Defined random signals were used as the input functions, which correspond to the real spectral density of road inequalities. For the proper analysis result, signal processing in the time and frequency domains was conducted. A further objective of the work is to develop guidelines for test methods for the technical conditions under normal operation of shock absorbers built into vehicles. | Analysis of the Forces Generated in the Shock Absorber for Conditions Similar to the Excitation Caused by Road Roughness | 10.1007/978-3-319-42408-8_30 |
2016-01-01 | We present a model to explain the bottomonium suppression observed in Pb $$+$$ + Pb collisions at Large Hadron Collider (LHC) energy, $$\sqrt{s_{NN}}=2.76$$ s N N = 2.76 TeV. A quasi-particle model (QPM) equation of state (EOS) for the Quark-Gluon Plasma (QGP) expanding under Bjorken’s scaling law at mid rapidity is employed. The present work incorporates the formation time based on the temperature of QGP, color screening during bottomonium production, gluon induced dissociation and collisional damping. The cold nuclear matter (CNM) effects, decay of higher resonances of bottomonium have also been included in the current work. The final suppression of the bottomonium states at mid rapidity is plotted as a function of centrality. Our results show reasonably good agreement with the recent centrality dependent bottomonium suppression data in the mid rapidity region obtained from CMS experiment at Large Hadron Collider (LHC). | Bottomonium Suppression at LHC Energy Based on the Temperature Dependent Formation Time | 10.1007/978-3-319-25619-1_18 |
2016-01-01 | In order to satisfy high-accuracy navigation, improve comprehensive calibration accuracy, improved two-point calibration based on Extended State Observer (ESO).Gave a brief analysis on traditional two-point calibration, restrictive navigating state and its shortage, then estimated platform horizontal errors based on EOS, improved the two-point calibration, then gave the algorithm simulation and numerical validate. The results indicate that traditional two-point calibration give a bad estimation result when carrier cannot satisfy navigating state, but new algorithm has the stronger applicability, reduce the restrictive navigating state and improve comprehensive calibration accuracy. | Research on Improvement of INS Two-Point Calibration in Horizontal Damping State | 10.2991/978-94-6239-145-1_41 |
2016-01-01 | Reduction of noise and vibration coming from the rail transport activities is an important objective of the environmental policy of the European Union, due to its impact on human and animal health. It has been identified that one of the major sources of noise and vibration in rail transport is from the interaction between the wheel and the rail, the so called rolling noise. One way to mitigate this noise is to attach polymeric damping elements to the rail. By modifying bulk properties of polymeric material we can modify its damping characteristics. In this chapter we demonstrated on the example of thermoplastic polyurethane (TPU) the effect of inherent hydrostatic pressure on the time- and frequency-dependent behavior of polymers. For the selected TPU material we found that increasing hydrostatic pressure from 1 to 2000 bar shifts frequency at which material exhibits its maximal damping properties (G″max) from 37 kHz to 235 Hz. It was also found that change of pressure changes values of storage modulus G′ up to 3.5 times (depending on the frequency), while the values of loss modulus G″ are changed up to 5.5 times. Using this property of polymeric materials we developed new generation damping elements composed of glass fiber textile tubes filled with pressurized granulated polymeric materials. Granular material with properly selected multimodal particle size distribution acts as pressurizing agent. At the same time the generated hydrostatic pressure changes frequency dependence of the granular material bulk properties. By modifying material bulk properties we can modify damping characteristics of the new generation damping elements. Applying these damping elements to the rail can substantially reduce vibration amplitudes as well as sound pressure levels, thus reducing exposure of human and animal to noise and vibration. | Effect of Pressure on Damping Properties of Granular Polymeric Materials | 10.1007/978-3-319-21762-8_13 |
2016-01-01 | Broadband impact excitation in structural dynamics is a common technique used to detect and characterize nonlinearities in mechanical systems since it excites many frequencies of a structure at once. Non-stationary time signals from transient ring-down measurements require time-frequency analysis tools to observe variations in frequency and energy dissipation as the response evolves. This work uses the short-time Fourier transform to estimate the instantaneous parameters from measured or simulated data. By combining the discrete Fourier transform with an expanding or contracting window function that moves along the time axis, the resulting spectra are used to estimate the instantaneous frequencies, damping ratios and complex Fourier coefficients. This method is demonstrated on a multi-degree-of-freedom beam with a cubic spring attachment. The amplitude-frequency dependence in the damped response is compared to the undamped nonlinear normal modes. A second example shows the results from experimental ring-down measurements taken on a beam with a lap joint, revealing how the mechanical interface introduces nonlinear frequency and damping parameters. | Instantaneous Frequency and Damping from Transient Ring-Down Data | 10.1007/978-3-319-29763-7_24 |
2016-01-01 | Underwater competitions confirm that the PID yaw controller is less efficient for low mass Autonomous Underwater Vehicle (AUV) to handle the robot uncertainties. Nonlinear hydrodynamic behavior, waves, current, AUV bouyance change, motor calibration variations, sensor disturbance and battery variations perturbate the PID control behavior a lot. Therefore, in this paper we present a model based robust controller to control the yaw heading of AUV CISCREA. The modeling result was verified with experiments, and the robust controller was simulated. | Underwater Vehicle Modeling and Control Application to Ciscrea Robot | 10.1007/978-3-319-32107-3_9 |
2016-01-01 | Various real-time correlation functions are defined (Wightman, retarded, advanced, time-ordered, spectral). Their analytic properties are discussed, and general relations between them are worked out for the case of a system in thermal equilibrium. Examples are given for free scalar and fermion fields. A physically relevant spectral function related to a composite operator is analyzed in detail. The so-called real-time formalism is introduced, and it is shown how it can be used to compute the same spectral function that was previously determined with the imaginary-time formalism. The need for resummations in order to systematically determine spectral functions in weakly coupled systems is stated. The concept of Hard Thermal Loops (HTLs), which implement a particular resummation, is introduced. HTL-resummed gauge field and fermion propagators are derived. The main plasma physics phenomena that the HTL resummation captures are pointed out. A warning is issued that although necessary HTL resummation is in general not sufficient for obtaining a systematic weak-coupling expansion. | Real-Time Observables | 10.1007/978-3-319-31933-9_8 |
2016-01-01 | The base vibration of a linear motor motion stage has been reduced with a passive reaction force compensation (RFC) mechanism based on a movable magnet track and springs. This paper presents the design procedure of an eddy-current damper (ECD) type RFC mechanism for a linear motor motion stage. The RFC mechanism with a movable magnet track and an ECD can overcome the disadvantages of the spring based RFC mechanism such as resonance and difficulty of assembly due to springs. A lumped parameter model for the ECD type RFC mechanism is derived considering sinusoidal magnetic flux density and the effective width of the ECD according to magnet track motion. Then, an iterative design procedure for ECD type RFC mechanisms is proposed to meet system requirements such as the transmission ratio of the reaction force and the maximum magnet track motion. Finally, a design example illustrates the effectiveness of the proposed design procedure for an ECD type RFC mechanism. | Eddy current damper type reaction force compensation mechanism for linear motor motion stage | 10.1007/s40684-016-0009-3 |
2016-01-01 | It has long been believed that the main oxidant created inside a bubble at the bubble collapse in aqueous solutions under strong ultrasound is OH radical. However, numerical simulations of chemical reactions inside an air bubble in water indicate that the main oxidant is not always OH radical but sometimes H_2O_2 or O atom. The lifetime of O atom in the gas–liquid interface region is, however, unknown partly due to unknown temperature in the region. It has been experimentally reported that the upper levels of OH vibration are overpopulated inside a sonoluminescing bubble compared to the equilibrium Boltzmann distribution from the analysis of OH line spectra in SL. However, the reason is unknown although it could be due to the excitation through chemical reactions. The acoustic field inside a sonochemical reactor is also not fully understood because bubbles strongly attenuate ultrasound and radiate acoustic waves into the liquid. The spatial distribution of bubbles is strongly inhomogeneous. The number density of bubbles temporally changes due to fragmentation, coalescence, and dissolution. The liquid surface vibrates under ultrasound. The vibration of the container’s wall also affects the acoustic field because acoustic waves are radiated from the vibrating walls. The bubble–bubble interaction on pulsation of a bubble is also discussed. | Unsolved Problems in Acoustic Cavitation | 10.1007/978-981-287-278-4_1 |
2016-01-01 | Movement facilitation has a fundamental role in the rehabilitation treatment of stroke survivors. However, its action mechanisms are still poorly understood. An open question is to identify the effect of the level of assistance on the recovery process. To address this topic, new insight on voluntary control and movement strategies during rehabilitation must be gained. Robot-assisted arm movements were examined in a task where subjects had to reach distal targets in the presence of assistive forces. As the training proceeded, subjects improved their performance and exercised with both the initial force level of the first session and with progressively decreasing levels of assistive force. We found that when stroke survivors became to execute voluntary movements with lower forces levels they decreased their voluntary control in the presence of higher forces, following a minimum effort trajectory. These findings provide a new important insight for the rehabilitation of stroke survivors, suggesting that passive mobilization and exercise with constant force, although useful for muscular reinforcement, may have a detrimental effect on voluntary control and movements planning. | A Computational Index to Describe Slacking During Robot Therapy | 10.1007/978-3-319-47313-0_19 |
2016-01-01 | Joints, interfaces, and frictional contact between two substructures can be modelled as discrete nonlinearities that connect the substructures. Over the past decade, a number of phenomenologically different approaches to modelling and simulating the dynamics of a jointed structure have been proposed. This research focuses on assessing multiple modelling techniques to predict the nonlinear dynamic behaviour of a bolted lab joint, including frequency based sub-structuring methods, harmonic balance methods, discontinuous basis function methods, and high fidelity FEA approaches. The regimes in which each method is best suited are identified, and recommendations are made for how to select a modelling method and for advancing numerical modelling of discrete nonlinearities. | Numerical Round Robin for Prediction of Dissipation in Lap Joints | 10.1007/978-3-319-15221-9_4 |
2016-01-01 | The viscoelastic properties Viscoelastic properties of carbon nanofiber (CNF) Carbon nanofiber reinforced polymer matrix composites are examined in this chapter. Temperature-dependent variations in the properties from subzero to above glass transition temperature Glass transition temperature ( T _ g ) is studied. Different compositions of CNF/polymer composites are evaluated for parameters such as storage modulus Storage modulus , loss modulus Loss modulus , and damping Damping parameter using a dynamic mechanical analyzer. The maximum use temperature and T _ g of such composites are also determined. The ability to tailor the properties by means of CNFs and improve the stability of reinforced polymer composites at high temperatures is important for aerospace applications that handle mechanical load under thermal extremes. | Dynamic Mechanical Analysis of CNF/Polymer Composites | 10.1007/978-3-319-23787-9_6 |
2016-01-01 | This work presents a strategy for testing and validating structures connected together with bolted joints, which are the most common components in mechanical structures. Considering the great number of coupled mechanical structures and research studies on this subject, the authors focused this research work on bolted flanges of aircraft engine casings. In fact, the coupling of engine casings is generally obtained by a large number of joints which assure the correct sealing at the flanges’ interfaces. From a finite element (FE) modelling perspective, joints are often modelled by either rigid connections or springs, otherwise incurring a very expensive computational time. This modelling approach is not a problem when dealing with low amplitude levels of vibrations. For higher levels of vibrations, joints and flanges cannot be considered rigidly connected and that exerted flexibility at the joints’ area can determine nonlinear dynamic behaviour. This work aims to study the dynamic behaviour of bolted flanges by using modal testing performed under controlled response amplitude. Two test structures, (1) a simple bolted flange test case and (2) a sector of a Rolls-Royce aero-engine casing, are tested under high level of vibrations. Both test structures are modelled by FE method, and nonlinear elements are used for modelling the flanges’ interfaces so as to perform prediction of nonlinear responses. These predictions are eventually correlated with the measured data. | Development of a test planning methodology for performing experimental model validation of bolted flanges | 10.1007/s11071-015-2382-9 |
2016-01-01 | In this chapter, a wide-area robust coordination method is proposed for HVDC- and FACTS-WADC. It can provide an effective damping on multiple inter-area oscillations excited by various operating conditions. A design procedure is planned as a way of executing the robust coordination for HVDC- and FACTS-WADC. In each step, the WADC design is formulated as a standard robust problem of H _2/ H _∞ output feedback control. The proposed coordination method is able to consider the output disturbance rejection problem, reduce the control effort, and ensure robustness against model uncertainties. | Robust Coordination of HVDC and FACTS Wide-Area Damping Controllers | 10.1007/978-3-662-48627-6_8 |
2016-01-01 | Dynamics of Langmuir solitons is considered in the framework of the extended nonlinear Schrödinger equation (NLSE), including a pseudo-stimulated-Raman-scattering (pseudo-SRS) term, caused by stimulated scattering on damping ion-sound waves. Also included are spatially decreasing second-order dispersion (SOD) and increasing self-phase modulation (SPM), caused by spatially decreasing electron temperature of plasma. It is shown that the wavenumber downshift of solitons, caused by the pseudo-SRS, may be compensated by an upshift provided by the decreasing SOD and increasing SPM coefficients. An analytical solution for solitons is obtained in an approximate form. Analytical and numerical results agree well. | Langmuir Solitons in Plasma with Inhomogeneous Electron Temperature and Space Stimulated Scattering on Damping Ion-Sound Waves | 10.1007/978-3-319-29608-1_19 |
2016-01-01 | Motivated by the current demands in high-performance structural analysis, and by a desire to better model systems with localized nonlinearities, analysts have developed a number of different approaches for modelling and simulating the dynamics of a bolted-joint structure. However, the types of conditions that make one approach more effective than the others remains poorly understood due to the fact that these approaches are developed from fundamentally and phenomenologically different concepts. To better grasp their similarities and differences, this research presents a numerical round robin that assesses how well three different approaches predict and simulate a mechanical joint. These approaches are applied to analyze a system comprised of two linear beam structures with a bolted joint interface, and their strengths and shortcomings are assessed in order to determine the optimal conditions for their use. | A Numerical Round Robin for the Prediction of the Dynamics of Jointed Structures | 10.1007/978-3-319-29763-7_20 |
2016-01-01 | The detection of structural damping is a crucial point in structural identification. Classic techniques usually refer to deterministic systems, since the assumption of randomness in the mechanical quantities implies non-trivial analytical difficulties in the development of both the direct and the inverse problem. In some recent works, starting from the statistics of mode-shapes and (undamped) frequencies, a perturbative approach has been introduced by the authors for the estimation of mean and variance of uncertain mass and stiffness. Here dissipative structures are considered; in detail, the method is applied for the stochastic structural identification of classically damped linear dynamic systems, dependent on a random parameter, assumed to be Gaussian. A numerical validation of the technique is then presented and discussed. | Dynamic Identification of Classically Damped Uncertain Structures | 10.1007/978-3-319-29754-5_12 |
2016-01-01 | A design of double resonant control combined with a model-free decoupling filter (MFDF) is presented in this paper. The design is demonstrated using the proposed MFDF to decouple a parallel multi-input multi-output (MIMO) system into several single-input single-output systems and applying a double resonant controller for vibration damping and cross coupling reduction in nanopositioners. Raster scan results of simulations based on an identified MIMO transfer function of a nanopositioning stage over an area of 4 μm × 0.4 μm with small RMS errors are demonstrated. Comparisons with using the double resonant controller alone show the effectiveness of the proposed controller. | Combined Model-Free Decoupling Control and Double Resonant Control in Parallel Nanopositioning Stages for Fast and Precise Raster Scanning | 10.1007/978-3-319-43506-0_5 |
2016-01-01 | This chapter is devoted to summarize different approaches for the imaging technique of elastography: Quasi-Static, Harmonic and Transient elastography, Models for viscoelasticity. This promising technique is a good example of interdisciplinary mathematical research and applications. | Elasticity Imaging | 10.1007/978-3-319-31323-8_10 |
2016-01-01 | Resonant analysis of a vibration system equipped with a nonlinear displacement-dependent (NDD) damper is investigated. The frequency of the external forcing is chosen to be close to the natural frequency of the system. The system is modeled and the approximate analytical solution of the governing equation is developed using the multiple scales method (MSM). Several case studies with various amounts of external force’s frequencies are performed to investigate the resonant excitation analysis. The proposed analytical solution is also verified by the fourth order Runge-Kutta method. Moreover, the performance of the used NDD damper is analyzed and compared with the ordinary linear damper through the same periodic resonant excitation. It is found that the NDD damper has a superior performance in reducing the vibration amplitude, compared to the traditional linear damper when resonance occurs. In addition, utilizing the NDD damper in the resonant-excited system provides a smaller force transmitted to the base than the system with the ordinary linear damper. | Resonant Analysis of Systems Equipped with Nonlinear Displacement-Dependent (NDD) Dampers | 10.1007/978-3-319-29739-2_8 |
2016-01-01 | Finite Element (F.E.) models need validating in order to reliably predict the dynamic properties of the system. One parameter that is necessary for updating the analytical models is the mode shape. The mode shapes obtained from analytical models are real-valued (normal modes), whereas the experimental mode shapes are more often than not complex-valued (complex modes). In order to be able to compare the experimental and analytical mode shapes, the former needs to be normalized. Two techniques to normalize the complex mode shapes will be discussed in this paper. The first technique is a pre-processing technique based on truncation of the α polynomial obtained from the Unified Matrix Polynomial Approach (UMPA) model of modal parameter estimation (MPE). The proposed technique eliminated the damping and normalized the complex modal vectors, however, the undamped natural frequencies deviated from that of the actual system. The disagreement in natural frequencies is explained with the help of 2 and 4 degree of freedom (DOF) analytical models. The second normalization method proposed is a post-processing technique based on the partial fraction method of residue synthesis. The technique successfully normalized the complex modal vectors with a very good correlation with the actual (complex) mode shapes resulting in a very high modal assurance criterion (MAC) value. | Normalization of Complex Mode Shapes by Truncation of Alpha-Polynomial | 10.1007/978-3-319-30249-2_6 |
2016-01-01 | An innovative modeling approach to reduce the whirling in the lathe machine using houdaille is presented by introducing the system excitation in the form of cutting forces between the cutting edge head and the workpiece. Houdaille damper is placed on the workpiece to minimize the whirling motion as much as possible. This involves nonhomogeneous boundary conditions with homogeneous equations. The mathematical modeling approach enabled us to solve the problem by modal analysis by transforming the problem into nonhomogeneous equations with homogenous boundary conditions. The proposed approach enables us to reduce the whirling motion at different locations on the cutting edge-workpiece system by different percentages. | Reducing whirling motion in the lathe machine using houdaille damper | 10.1007/s12206-015-1203-x |
2016-01-01 | Shock absorbers of electronic devices can reduce vibration and protect devices. If shock absorbers don’t work normally, vibration cannot be effectively reduced which may lead to devices’ degradation or even failure. Through a method combining theoretical analysis, simulation and test, failure mechanisms of dry friction damping shock absorber were analyzed, including brittle fracture of spring, fatigue fracture of spring and wear of damping disk. By building the 3D solid model and performing finite element analysis which consists of statics analysis, modal analysis and random vibration analysis, stresses of corresponding positions are obtained. Additionally, the morphology of brittle fracture, measure force-displacement relation of spring and hardness of shock absorber’s inner wall are observed by some instruments. Finally, we know the main failure mechanism is fatigue fracture of the spring, and obtain the life estimation of shock absorber. The result provides basis for later reliability tests and design improvement. | Failure Mechanism Analysis and Life Estimation of Dry Friction Damping Shock Absorber | 10.2991/978-94-6239-148-2_58 |
2016-01-01 | From the manifold strategies that nature offers to materials under overload conditions, we describe two: the fibrous and multi-layered system of the bark of the Giant Sequoia, which possesses an impressive damping mechanism, and the spines of pencil and lance sea urchins. The latter introduce a new concept to energy dissipation in brittle construction materials, namely quasi-ductility by multiple local fracturing. The potential for transfer as bioinspired technical solutions is high as the biological role models combine several advantages such as lightweight, recyclability and high protective efficiency. We demonstrate that, in principle, the concepts found in the biological role models can be transferred to concrete-based building materials. | Plants and Animals as Source of Inspiration for Energy Dissipation in Load Bearing Systems and Facades | 10.1007/978-3-319-46374-2_7 |
2016-01-01 | Figure 4.1 shows the configuration of a shunt voltage source converter (VSC)-based unit connected to high-voltage transmission line through a step-down transformer. x_s is the equivalent reactance of the step-down transformer. | Single-Machine Infinite-Bus Power Systems Installed with VSC-Based Stabilizers | 10.1007/978-1-4899-7696-3_4 |
2016-01-01 | Reducing the magnitude of the vibrations transmitted to a user’s hands through the loop handle and grip of a string trimmer is a priority for maintaining both health and comfort. Prior work on internal-combustion (IC) powered string trimmers has indicated that Lodengraf™ damping may be effective in reducing vibration amplitude at both the loop handle and grip. Lodengraf damping utilizes lightweight, low-density particles added to a vibrating device, either as a fill in existing cavities or as a wrap surrounding the device. The mechanism for the damping is that vibrations generated by the device are absorbed into the Lodengraf particles, where the energy of the vibrations is converted to heat and released before they can be transmitted to the user. In this set of experiments performed on battery-powered string trimmers, the effectiveness of applying Lodengraf particles using specially designed 3D printed loop handles as well as a clam-shell shaft enclosure, all comprised from ABS is explored. The 3D printed parts were designed to be hollow, forming cavities to accommodate the Lodengraf materials. The Lodengraf was found to be effective at frequencies above 200 Hz. Both trimmers have a first fundamental frequency that falls below the cutoff frequency for effective Lodengraf damping, but the approach effectively reduced the amplitude of higher frequency harmonics generated. | Evaluating the Effectiveness of a Lodengraf Damping Approach for String Trimmers | 10.1007/978-3-319-30084-9_34 |
2016-01-01 | We consider the half-linear differential equation with an unbounded damped term, $$\begin{aligned} (\phi _p(x'))' + h(t)\!\,\phi _p(x') + \omega ^p\phi _p(x) = 0, \end{aligned}$$ ( ϕ p ( x ′ ) ) ′ + h ( t ) ϕ p ( x ′ ) + ω p ϕ p ( x ) = 0 , where $$\omega > 0$$ ω > 0 and $$\phi _p(z) = |z|^{p-2}z$$ ϕ p ( z ) = | z | p - 2 z with $$p > 1$$ p > 1 . The divergence speed of the damping coefficient $$h(t)$$ h ( t ) is assumed to be determined by some parameters. By using the relations between the index number $$p$$ p and the parameters, we describe some criteria judging whether the equilibrium of this equation is globally asymptotically stable or not. We also present parameter diagrams to clarify the relations between them. | Parameter diagram for global asymptotic stability of damped half-linear oscillators | 10.1007/s00605-014-0695-2 |
2016-01-01 | The geometric layout and physical properties of a viscoelastic damping material have a significant influence on the damping performance of a passive constrained layer damping (PCLD) structure. This paper presents a two-scale optimization method and aims to find the optimal microstructural configuration of the viscoelastic material (i.e., the optimal effective properties of the material) with maximum modal loss factors of the macrostructures. The modal loss factor is obtained by using the Modal Strain Energy (MSE) method. The material microstructure is assumed to be homogeneous in the macro-scale, i.e., the macrostructure is composed of periodic unit cells (PUC). In the optimization formulation, the relative densities are introduced as the design variables for the material microstructure design, based upon the idea of the Solid Isotropic Material with Penalization (SIMP) method of topology optimization. The modal loss factor of the structure is assigned as the objective function. All the sensitivities of the modal loss factor with respect to the design variables are derived analytically and the optimization problem is solved by Method of Moving Asymptote (MMA) method. Several examples of the design optimization of viscoelastic cellular materials are presented to demonstrate the validity of the method. The effectiveness of the design method is illustrated by comparing a solid and an optimized cellular viscoelastic material as applied to a cantilever beam with the PCLD treatment. | Microstructural topology optimization of viscoelastic materials for maximum modal loss factor of macrostructures | 10.1007/s00158-015-1305-1 |
2016-01-01 | Currently, to obtain an understanding of the frequency and damping of the modes of a rotating system, an impact test or a shaker test is done to find the frequency at which the modes of the system exist. Then, an operating test is done to obtain an understanding of the orders of the system. A Mode Enhanced Order Track (MEOT) can be used to obtain the frequency and damping of various modes directly from the operating data of a rotating system but it cannot find modes which are very close together in frequency or those that are repeated. The MEOT is a method described in Dr J.R. Blough’s PhD dissertation, which has not been tested on data obtained from an actual rotating system. This data was taken from a Toro Leaf Blower, using a laser tachometer and 7 triaxial sensors. Using Mode enhanced Order Tracking, the frequency and damping of different modes was found. These were then compared to the results obtained from an Impact Test performed on the Toro Leaf Blower. This method was also tested after using the virtual sensor concept on the data. A virtual sensor was created for each triaxial sensor. The results obtained from the impact test, MEOT and the MEOT performed on the virtual sensor data were then compared and analysed. | Estimation of Frequency and Damping of a Rotating System Using MEOT and Virtual Sensor Concept | 10.1007/978-3-319-29910-5_3 |
2016-01-01 | To illustrate the power and the pitfalls of Bionic Optimization, we will show some examples spanning classes of applications and employing various strategies. These applications cover a broad range of engineering tasks. Nevertheless, there is no guarantee that our experiences and our examples will be sufficient to deal with all questions and issues in a comprehensive way. As general rule it might be stated, that for each class of problems, novices should begin with a learning phase. So, in this introductory phase, we use simple and quick examples, e.g., using small FE-models, linear load cases, short time intervals and simple material models. Here beginners within the Bionic Optimization community can learn which parameter combinations to use. In Sect. 3.3 we discuss strategies for optimization study acceleration. Making use of these parameters as starting points is one way to set the specific ranges, e.g., number of parents and kids, crossing, mutation radii and, numbers of generations. On the other hand, these trial runs will doubtless indicate that Bionic Optimization needs large numbers of individual designs, and considerable time and computing power. We recommend investing enough time preparing each task in order to avoid the frustration should large jobs fail after long calculation times. | Application of Bionic Optimization | 10.1007/978-3-662-46596-7_5 |
2016-01-01 | The mathematical models of processes in technology, economics, and nature are often nonlinear. Nonlinear problems often also arise in mathematics, an example of this is finding roots of a general function (e.g. of a high order polynomial). As the case of polynomials shows, nonlinear equations mostly have several roots. And often the user does not accept our tediously obtained solution and asks us to find another one. | Nonlinear Equations and Systems | 10.1007/978-3-319-44660-8_7 |
2016-01-01 | Modern drivetrain, new types of engines and the effort to reduce the weight of the system improves the efficiency of powertrain. But also it is the way that the given system much more sensitive to the vibration. Today’s damper system, damped clutch disc and dual mass flywheel cannot remove or shift the resonance field from working area of engine in all cases which powertrain can have. Therefore we proposed a new type of the dual mass flywheel in the framework of our workplace in order to improve behaviour of powertrain in vibration field. | Pneumatic Dual Mass Flywheel – Damper Concept for Downspeeding | 10.1007/978-3-319-22762-7_54 |
2016-01-01 | Inflammatory processes play a key role in the initiation of the acute painful vaso-occlusive crises that constitute the main cause of hospitalization in individuals with sickle cell anemia, as well as many of its numerous complications, including autosplenectomy, pulmonary hypertension, acute chest syndrome, leg ulcers, nephropathy and stroke. Ischemia-reperfusion injury (due to microvascular and macrovascular occlusions), membrane alterations of the sickle red blood cell, and hemolysis may all trigger endogenous proinflammatory signals (damage-associated molecular patterns-DAMPs) that lead to the vicious circle of pan-cellular activation, inflammatory mediator release, leukocyte recruitment and occlusive mechanisms that result in the chronic inflammatory state that is associated with sickle cell anemia. We, herein, review the probable primary inflammatory triggers that initiate inflammatory mechanisms in the disease and postulate the cells and molecules that may contribute to establish chronic inflammation. The anti-inflammatory effects of hydroxyurea are discussed, as are novel anti-inflammatory approaches currently under study. | Inflammation and Sickle Cell Anemia | 10.1007/978-3-319-06713-1_8 |
2016-01-01 | This study aims to evaluate the seismic performance of steel moment resisting frames upgraded with shape memory alloy (SMA)-based self-centering viscous dampers. The superelastic viscous damper (SVD) relies on SMA cables for re-centering capability and employs viscoelastic (VE) damper that consists of two layers of a high damped (HD) blended butyl elastomer compound to augment its energy dissipation capacity. First, the design and mechanical behavior of SVDs are described. A nine-story steel frame building is selected for the numerical analyses. The building is analyzed as (1) a conventional special moment resisting frame (SMRF), (2) a dual SMRF-buckling restrained brace (BRB) system, and (3) a SMRF with SVDs. A model of the steel building for each configuration is developed to determine the dynamic response of the structure. The incremental dynamic analysis is used to evaluate the behavior of each building under seven ground-motion records. The analytical results indicate that the SVDs improve the response of steel frame buildings under different level of seismic hazards. | Incremental Dynamic Analyses of Steel Moment Resisting Frames with Superelastic Viscous Dampers | 10.1007/978-3-319-29910-5_17 |
2016-01-01 | In this paper, we study an interconnected system of a Schrödinger and a wave equation with Kelvin-Voigt damping Kelvin-Voigt (K-V) damping, where the K-V damped wave equation performs as a Dynamic feedback controller dynamic feedback controller. We show that the system operator generates a C _0-semigroup of contractions in the energy state space, and the system is well-posed. By detailed spectral analysis, we know that the spectral of the system operator composes of two parts, point spectrum and continuous spectrum. Moreover, the points in the spectra all have negative real parts. It follows that the C _0-semigroup C _0-semigroup generated by the system operator achieves Asymptotic stability asymptotic stability. | Dynamic Boundary Stabilization of a Schrödinger Equation Through a Kelvin-Voigt Damped Wave Equation | 10.1007/978-3-319-30379-6_12 |
2016-01-01 | Hybrid Simulation (HS) and Real Time Hybrid Simulation (RTHS) are recognized as powerful techniques for civil infrastructure assessment. Typically in HS/RTHS, a critical component is isolated as the physical component in the simulation, while the remainder of the structure is modeled numerically. This approach enables response evaluation on both local and global level. Broadening the applications that would like to use HS and RTHS requires that we examine more complex structural systems. When multiple components in the structural system have the same design and contribute roughly equally to the response, it may be difficult to select the most appropriate physical component. However, modeling errors in those structural components that reside in the numerical component can influence the accuracy of the global responses. Model updating based on the responses of the physical component for determining the model parameters will reduce the influence of the modeling errors. Advances in online system identification techniques and their application to more complex structural models, enables the option of incorporating online model updating into HS/RTHS. Through a simplified case study, we explore the feasibility of HS/RTHS with model updating (HSMU/RTHSMU). A two story steel frame equipped with two identical magnetic-rheological (MR) dampers. In RTHS, the first story MR damper is loaded as the physical component and the remainder of the structure, including the frame and the second MR damper, is numerically modeled. Simulation and conventional RTHS response are considered. In each case the second story MR damper model uses one initial parameter set, which is then updated online using identified parameters based on the physical component (RTHSMU). Online model updating is then investigated using a validation signal, and the fidelity and advantages of RTHSMU are discussed. | Real Time Hybrid Simulation with Online Model Updating on Highly Nonlinear Device | 10.1007/978-3-319-30084-9_32 |
2016-01-01 | A strategy of parallel computing (HPC) is proposed to solve the problem of inverse kinematics in 3D with multiple objectives using the damped least squares method, also known as the Levenberg-Marquardt method. The program solves the problem of moving one or more end-effectors of a robot to a desired target position by manipulating its joints, which are the degrees of freedom. The HPC strategy consists in parallelizing the motion calculations required to accomplish the different objectives. Tests were conducted with a simulation of a ping-pong game using multiple balls. Robots are placed at each end of a table, the movement of the balls is predicted integrating its position numerically, and the robots’ end-effectors are moved to hit the balls. The amount of end-effectors correspond to the number of balls, with priorities assigned to each of them. | Parallelized 3D Inverse Kinematics with Multiple Objectives | 10.1007/978-3-319-32243-8_7 |
2015-12-12 | This paper is concerned with the long-time behavior of solutions to the weakly damped wave equation with lower regular forcing defined on the entire space R 3 $\mathbb{R}^{3}$ . The existence of a global attractor in H 1 ( R 3 ) × L 2 ( R 3 ) $H^{1}(\mathbb{R}^{3}) \times L^{2}(\mathbb{R}^{3})$ is proven. Moreover, under some additional condition, the translational regularity of the attractor is established. | Remark on global attractor for damped wave equation on
R
3
$\mathbb{R}^{3}$
| 10.1186/s13662-015-0717-y |
2015-12-03 | We consider the periodic initial value problem associated to the generalized Benjamin-Bona-Mahony equation with generalized damping on the one dimensional torus. In contrast to the classical BBM equation, the main difference is that the generalized equation contains two nonlocal operators, and the main difficulty comes from two nonlocal operators. By the fixed point theorem, we prove that the periodic initial value problem is locally well-posed. We also prove that if the solution exists globally in time, it exhibits some asymptotic behavior. | Local well-posedness of generalized BBM equations with generalized damping on 1D torus | 10.1186/s13661-015-0494-2 |
2015-12-01 | This paper is concerned with the study of the uniform decay rates of the energy associated with the wave equation subject to a locally distributed viscoelastic dissipation and a nonlinear frictional damping $$u_{tt}- \Delta u+ \int_0^t g(t-s){\rm div}[a(x)\nabla u(s)]\,{\rm d}s + b(x) f(u_t)=0\,\quad {\rm on} \quad \Omega\times]0,\infty[,$$ u t t - Δ u + ∫ 0 t g ( t - s ) div [ a ( x ) ∇ u ( s ) ] d s + b ( x ) f ( u t ) = 0 on Ω × ] 0 , ∞ [ , where $${\Omega\subset\mathbb{R}^n, n\geq 2}$$ Ω ⊂ R n , n ≥ 2 is an unbounded open set with finite measure and unbounded smooth boundary $${\partial\Omega = \Gamma}$$ ∂ Ω = Γ . Supposing that the localization functions satisfy the “competitive” assumption $${a(x)+b(x)\geq\delta>0}$$ a ( x ) + b ( x ) ≥ δ > 0 for all $${x\in \Omega}$$ x ∈ Ω and the relaxation function g satisfies certain nonlinear differential inequalities introduced by Lasiecka et al. (J Math Phys 54(3):031504, 2013 ), we extend to our considered domain the prior results of Cavalcanti and Oquendo (SIAM J Control Optim 42(4):1310–1324, 2003 ). In addition, while in Cavalcanti and Oquendo ( 2003 ) the authors just consider exponential and polynomial decay rate estimates, in the present article general decay rate estimates are obtained. | General decay rates for the wave equation with mixed-type damping mechanisms on unbounded domain with finite measure | 10.1007/s00033-015-0547-5 |
2015-12-01 | The initial-boundary value problem for a class of nonlinear hyperbolic equations system in bounded domain is studied. The existence of global solutions for this problem is proved by constructing a stable set, and obtain the asymptotic stability of global solutions by means of a difference inequality. | Existence and asymptotic behavior for systems of nonlinear hyperbolic equations | 10.1007/s11766-015-3083-3 |
2015-12-01 | The present study investigates the thermo-elastic damping (TED) of transversal vibration in a functionally graded piezoelectric (FGP) micro-beam resonator. The model is a functionally graded silicon-piezoelectric fully clamped micro beam exposed to a DC piezoelectric tuning voltage. The object is to propose a novel FGP MEM system, with a controllable thermo-elastic damping. It is shown that the functionality of the material distribution not only reduces the TED ratio, but also enables tuning the resonance frequency of the resonator due to the piezoelectric actuation. The effects of portion of piezoelectric material, geometrical dimensions, the ambient temperature and tuning DC voltage, on the quality factor of the flexural vibrations of the structure is analyzed through solving the thermo elastically coupled dynamic equations of the motion. | Thermo-elastic damping in a functionally graded piezoelectric micro-resonator | 10.1007/s10999-014-9285-7 |
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