Physics-based seismic analysis of ancient wood structure:fault-to-structure simulation

Based on the domain reduction method,this study employs an SEM-FEM hybrid workflow which integrates the advantages of the spectral element method(SEM)for flexible and highly efficient simulation of seismic wave propagation in a three-dimensional(3D)regional-scale geophysics model and the finite element method(FEM)for fine simulation of structural response including soil-structure interaction,and performs a physics-based simulation from initial fault rupture on an ancient wood structure.After verification of the hybrid workflow,a large-scale model of an ancient wood structure in the Beijing area,The Tower of Buddhist Incense,is established and its responses under the 1665 Tongxian earthquake and the 1730 Yiheyuan earthquake are simulated.The results from the simulated ground motion and seismic response of the wood structure under the two earthquakes demonstrate that this hybrid workflow can be employed to efficiently provide insight into the relationships between geophysical parameters and the structural response,and is of great significance toward accurate input for seismic simulation of structures under specific site and fault conditions.

DISCREPANCIES IN THE REGRESSION MODELLING OF RECRYSTALLIZATION RATE AS USING THE DATA FROM PHYSICAL SIMULATION TESTS

The analysis of numerous experimental equations published in the literature reveals awide scatter in the predictions for the static recrystallization kinetics of steels. Thepowers of the deformation variables, strain and strain rate, similarly as the powerof the grain size vary in these equations. These differences are highlighted and thetypical values are compared between torsion and compression tests. Potential errorsin physical simulation testing are discussed.

Physics-based Modeling and Simulation for Motional Cable Harness Design

The design work of motional cable in products is vital due to the difficulty in estimating the potential issues in current researches.In this paper,a physics-based modeling and simulation method for the motional cable harness design is presented.The model,based on continuum mechanics,is established by analyzing the force of microelement in equilibrium.During the analysis procedure,three coordinate systems：inertial,Frenet and main-axis coordinate systems are used.By variable substitution and dimensionless processing,the equation set is discretized by differential quadrature method and subsequently becomes an overdetermined nonlinear equation set with boundary conditions solved by Levenberg-Marquardt method.With the profile of motional cable harness obtained from the integral of arithmetic solution,a motion simulation system based on＂path＂and＂profile＂as well as the experimental equipments is built.Using the same parameters as input for the simulation and the real cable harness correspondingly,the issue in designing,such as collision,can be easily found by the simulation system.This research obtains a better result which has no potential collisions by redesign,and the proposed method can be used as an accurate and efficient way in motional cable harness design work.

MODELING AND SIMULATION OF COMPOUND CLUTTER FOR COASTAL ENVIRONMENT

This paper introduces a novel clutter power model of coastal compound and deduces the statistic characteristics and the arithmetics of model parameter estimation algorithm. Then, a novel coastal compound distributed model of the clutter amplitude is proposed and its statistic character- istics are studied. Subsequently, the nonlinear relation of autocorrelation function is deduced between the coastal compound clutter random sequences and the correlated Gaussian random sequences, which is the important prerequisite for the clutter simulation based on the ZMNL (Zero Memory NonLin- earity). Lastly, the advantage of the algorithm is demonstrated by a feasible simulation of the gen- eration of the random coastal compound clutter sequences.

Numerical Simulation of Dynamic Response of A Net Cage for Flatfish in Waves

A numerical model of flatfish cage is built based on the lumped mass method and the principle of rigid body kinematics. To validate the numerical model, a series of physical model tests are conducted in the wave flume. The numerical results correspond well with the data sets from physical model test. The effect of weight of bottom frame, height of fish net and net shape on motion responses of fish cage and tension force on mooring lines is then analyzed. The results indicate that the vertical displacements of float collar and bottom frame decrease with the increase in the weight of bottom frame; the maximum tension force on mooring lines increases with the increasing weight of bottom frame. The inclination angles of float collar and bottom frame decrease with the increasing net height; the maximum tension force increases obviously with the increase of net height.

Numerical simulation of non-Archie electrophysical property of saturated rock with lattice Boltzmann method

The electrophysical property of saturated rocks is very important for reservoir identification and evaluation. In this paper, the lattice Boltzmann method （LBM） was used to study the electrophysical property of rock saturated with fluid because of its advantages over conventional numerical approaches in handling complex pore geometry and boundary conditions. The digital core model was constructed through the accumulation of matrix grains based on their radius distribution obtained by the measurements of core samples. The flow of electrical current through the core model saturated with oil and water was simulated on the mesoscopic scale to reveal the non-Archie relationship between resistivity index and water saturation （I-Sw）. The results from LBM simulation and laboratory measurements demonstrated that the I-Sw relation in the range of low water saturation was generally not a straight line in the log-log coordinates as described by the Archie equation. We thus developed a new equation based on numerical simulation and physical experiments. This new equation was used to fit the data from laboratory core measurements and previously published data. Determination of fluid saturation and reservoir evaluation could be significantly improved by using the new equation.

A P.hysical Numerical Ionospheric Model and Its Simulation Results

This paper describes the construction of a one-dimensional time-dependent theoretical ionospheric model, which is based on numerical solution of continuity and momentum equations for , and NO+. The model is designed to have an option to incorporate the observational ionospheric characteristic parameters into the numerical model to indirectly determine the upper boundary condition when solving the transport equations of O+. A preliminary simulation result of the model when used to simulate the ionosphere during April 18 ~ May 10, 1998, which includes both quiet and disturbed periods, showed that the model constructed is able to reproduce the observational results reasonably well both for quiet and disturbed periods.

Simulation Experiments of Land Surface Physical Processes and Ecological Effect over Different Underlying Surface

Based on the existing Land Surface Physical Process Models(Deardorff, Dickinson, LIU, Noilhan, Seller, ZHAO), a Comprehensive Land Surface Physical Process Model (CLSPPM) is developed by considering the different physical processes of the earth's surface-vegetation-atmosphere system more completely. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feas...

Numerical Simulation of Ionization Enhancement in the Topside Ionosphere of Cusp Foot-Point Region Caused by Low Energy Particle Precipitation

The Graz Ionospheric Flux Tube Simulations （GIFTS） has been improved. The improved GIFTS model was used to numerically investigate the energy particle precipitation on the distribution of electron density in the ionospheric cusp foot-point region under conditions of large plasma convection during magnetic storm. After including the effects of low energy incident particles, the ionospheric electron densities increase remarkably above altitude of -250 km, showing a peak at about 350 km. The percent enhancements of electron densities increase gradually with altitude, exceed- ing 60% near the upper boundary of the calculation. The calculated ionospheric F2-peak was remarkably enhanced and lifted up by the incident low energy electrons.

Topology-Based and Event-Oriented Approach to Simulation of Cyber-Physical Systems

A simulation model for cyber-physical systems(CPSs)was presented.The model was developed by the method of combination of topology-based and event-oriented that could be used to simulate systems with routing flexibility,service-selection flexibility and service- mode flexibility overall by integrating the strategies related.The validity of the model has been verified by two extensive experiments.

Model test and numerical simulation of a new prefabricated double-row piles retaining system in silty clay ground

This paper introduces a new prefabricated recyclable double-row piles retaining system for excavations in silty clay ground.Laboratory model test and numerical simulation are conducted to study the system behavior upon excavation.The horizontal displacement(δ_(h)),Von Mises stress(δ_(M)),strain(ε),ground surface settlement(δ_(v)),and earth pressure are systematically investigated.Furthermore,the monitoring data of 13 excavation cases supported by double-row piles retaining system are presented and discussed.The experimental results can basically match the numerical results,and the maximumδ_(M),maximum bending moment(M_(max)),maximum horizontal displacement(δ_(hm))of structural members are all less than the tolerance limits.The ground surface settlement model of double-row piles retaining system consists of three zones,i.e.,rebound influence zone,primary influence zone and secondary influence zone.The dhm values are 0.07%–1.42%of the excavation depth(He).The maximum ground surface settlement(δ_(vm))is generally less than dhm.The ratio ofδ_(vm)=δ_(hm)varies between 0.09 and 0.76,with an average value of 0.5.The observed earth pressure on the retained side of front pile(paf)is about 0.53–0.57γH below the excavation surface.Above the excavation surface,p_(af)decreases dramatically when getting closer to the ground surface.

Performance simulation method and state of health estimation for lithium-ion batteries based on aging-effect coupling model

Accurate simulation of characteristics performance and state of health(SOH)estimation for lithium-ion batteries are critical for battery management systems(BMS)in electric vehicles.Battery simplified electrochemical model(SEM)can achieve accurate estimation of battery terminal voltage with less computing resources.To ensure the applica-bility of life-cycle usage,degradation physics need to be involved in SEM models.This work conducts deep analysis on battery degradation physics and develops an aging-effect coupling model based on an existing improved single particle(ISP)model.Firstly,three mechanisms of solid electrolyte interface(SEI)film growth throughout life cycle are analyzed,and an SEI film growth model of lithium-ion battery is built coupled with the ISP model.Then,a series of identification conditions for individual cells are designed to non-destructively determine model parameters.Finally,battery aging experiment is designed to validate the battery performance simulation method and SOH estimation method.The validation results under different aging rates indicate that this method can accurately es-timate characteristics performance and SOH for lithium-ion batteries during the whole life cycle.

Meshless methods for physics-based modeling and simulation of deformable models

As 3D digital photographic and scanning devices produce higher resolution images, acquired geometric data sets grow more complex in terms of the modeled objects＇ size, geometry, and topology. As a consequence, point-sampled geometry is becoming ubiquitous in graphics and geometric information processing, and poses new challenges which have not been fully resolved by the state-of-art graphical techniques. In this paper, we address the challenges by proposing a meshless computational framework for dynamic modeling and simulation of solids and thin-shells represented as point sam- ples. Our meshless framework can directly compute the elastic deformation and fracture propagation for any scanned point geometry, without the need of converting them to polygonal meshes or higher order spline representations. We address the necessary computational techniques, such as Moving Least Squares, Hierarchical Discretization, and Modal Warping, to effectively and efficiently compute the physical simulation in real-time. This meahless computational framework aims to bridge the gap between the point-sampled geometry with physics-based modeling and simulation governed by partial differential equations.

Computer simulation to arc spraying

The arc spraying process is divided into two stages: the first stage is atomization-spraying stream (ASS) and the second one is spraying deposition (SD). Then study status is described of both stages’ physical model and corresponding controlling-equation. Based on the analysis of study status, the conclusion as follows is got. The heat and mass transfer models with two or three dimensions in ASS stage should be established to far deeply analyses the dynamical and thermal behavior of the overheat droplet. The statistics law of overheated droplets should be further studied by connecting simulation with experiments. More proper validation experiments should be designed for flattening simulation to modify the models in SD stage.

Vector Shift Method for Islanding Detection Based on Simulation Test

Vector shift(VS)is one of the typical methods used for islanding detection in distributed generations.This paper investigates the impact of both the active power imbalance and load variation on VS method.The investigation was conducted via simulation test in the power system dynamic simulation laboratory of Shandong University.The results show that it will take longer time for the VS relay to detect islanding state with the decrease of active power imbalance.In some cases,the vector shift angle is smaller than the setting and VS method would not be able to detect islanding state.In addition,the performance of VS method is impacted by the load variation in normal operation in which the distributed generator is operated in parallel with the main grid.The simulation results show that VS method would cause nuisance tripping if the load changes sharply. It can be summarized that VS method would be unable to reliably discriminate islanding state and normal system disturbances in some cases.

Mechanical behaviors of backfill-rock composites: Physical shear test and back-analysis

The shear behavior of backfill-rock composites is crucial for mine safety and the management of surface subsidence.For exposing the shear failure mechanism of backfill-rock composites,we conducted shear tests on backfill-rock composites under three constant normal loads,compared with the unfilled rock.To investigate the macro-and meso-failure characteristics of the samples in the shear tests,the cracking behavior of samples was recorded by a high-speed camera and acoustic emission monitoring.In parallel with the experimental test,the numerical models of backfill-rock composites and unfilled rock were established using the discrete element method to analyze the continuous-discontinuous shearing process.Based on the damage mechanics and statistics,a novel shear constitutive model was proposed to describe mechanical behavior.The results show that backfill-rock composites had a special bimodal phenomenon of shearing load-deformation curve,i.e.the first shearing peak corresponded to rock break and the second shearing peak induced by the broken of aeolian sand-cement/fly ash paste backfill.Moreover,the shearing characteristic curves of the backfill-rock composites could be roughly divided into four stages,i.e.the shear failure of the specimens experienced:stage I:stress concentration;stage II:crack propagation;stage III:crack coalescence;stage IV:shearing friction.The numerical simulation shows that the existence of aeolian sand-cement/fly ash paste backfill inevitably altered the coalescence type and failure mode of the specimens and had a strengthening effect on the shear strength of backfillrock composites.Based on damage mechanics and statistics,a shear constitutive model was proposed to describe the shear fracture characteristics of specimens,especially the bimodal phenomenon.Finally,the micro-and meso-mechanisms of shear failure were discussed by combining the micro-test and numerical results.The research can advance the better understanding of the shear behavior of backfill-rock composites and contribute to the safety of mining engineering.

Case study on the mechanics of NPR anchor cable compensation for large deformation tunnel in soft rock in the Transverse Mountain area,China

A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced during the tunnel construction.To mitigate this problem,a support system was designed incorporating negative Poisson ratio(NPR)anchor cables with negative Poisson ratio effect.Physical model experiments,field experiments,and numerical simulation experiments were conducted to investigate the compensation mechanical behavior of NPR anchor cables.The large deformations of soft rocks in the Daliangshan Tunnel are caused by a high ground stress,a high degree of joint fracture development,and a high degree of surrounding rock fragmentation.A compensation mechanics support system combining long and short NPR anchor cables was suggested to provide sufficient counter-support force(approximately 350 kN)for the surrounding rock inside the tunnel.Comparing the NPR anchor cable support system with the original support system used in the Daliangshan tunnel showed that an NPR anchor cable support system,combining cables of 6.3 m and 10.3 m in length,effectively prevented convergence of surrounding rock deformation,and the integrated settlement convergence value remained below 300 mm.This study provides an effective scientific basis for resolving large deformation problems in deeply buried soft rocks in western transverse mountain areas.

The influence of inter-band rock on rib spalling in longwall panel with large mining height

In order to improve rib stability,failure criteria and instability mode of a thick coal seam with inter-band rock layer are analysed in this study.A three-dimensional mechanical model is established for the rib by considering the rock layer.A safety factor is defined foy the rib,and it is observed that the safety factor exhibits a positive correlation with the thickness and strength of the inter-band rock.A calculation method for determining critical parameters of the rock layer is presented to ensure the rib stability.It is revealed that incomplete propagation of the fracture at the hard rock constitutes a fundamental prerequisite for ensuring the rib stability.The influence of the position of the inter-band rock in the coal seam on failure mechanism of the rib was thoroughly investigated by developing a series of physical models for the rib at the face area.The best position for the inter-band rock in the coal seam is at a height of 1.5 m away from the roof line,which tends to provide a good stability state for the rib.For different inter-band rock positions,two ways of controlling rib by increasing supports stiffness and flexible grouting reinforcement are proposed.

Physics of Failure(PoF)-Based Reliability and Performance Integrating Modeling Method and Software for Electromechanical Product

Electromechanical product's reliability is affected by uncertainty as well as performance degeneration during its life cycle.The present reliability and performance integrating modeling methods have obvious deficiencies in long period reliability analysis and assessment when applied to such system.A novel integrating modeling method based on physics of failure(PoF)and a simulation algorithm that considers uncertainty and degeneration are proposed in this paper to compute maintenance free operation period or maintenance free operation period survivability which is used to assess long period reliability of system.Furthermore,the concept design of this kind of software based on the above theory is also introduced.A case study of servo valve demonstrates the feasibility of the method and usability of the software in this research.

Constitutive model for methane desorption and diffusion based on pore structure differences between soft and hard coal

This paper aims to improve the accuracy and applicability of gas diffusion mathematical models from coal particles. Firstly, a new constitutive model for gas diffusion from coal particles with tri-disperse pore structure is constructed by considering the difference in characteristics between soft coal and hard coal.The analytical solution is then derived, that is, the quantitative relationship between gas diffusion rate(Qt/Q_∞) and diffusion time(t), The pore structure parameters of soft coal and hard coal from Juji coal mine are determined. Gas diffusion rules are numerically calculated and investigated by physical simulation methods. Lastly, the applicability of this model is verified. The results show that the homogeneous model only applies to the gas diffusion process of hard coal during the initial 10 min. The calculation results from this model and the physical experimental results of soft coal and hard coal are nearly identical during the initial 30 min.