A class of hybrid algorithms of real-time simulation based on evaluation of non-integerstep right-hand side function are presented in this paper. And some results of the convergence and stability of the algorithms are...A class of hybrid algorithms of real-time simulation based on evaluation of non-integerstep right-hand side function are presented in this paper. And some results of the convergence and stability of the algorithms are given. Using the class of algorithms, evaluation for the right-hand side function is needed once in every integration-step. Moreover, comparing with the other methods with the same amount of work, their numerical stability regions are larger and the method errors are smaller, and the numerical experiments show that the algorithms are very effective.展开更多
In this paper, a mathematical model of real-time simulation is given, and the problem of convergence on real-time Runge-Kutta algorithms is analysed. At last a theorem on the relation between the order of compensation...In this paper, a mathematical model of real-time simulation is given, and the problem of convergence on real-time Runge-Kutta algorithms is analysed. At last a theorem on the relation between the order of compensation and the convergent order of real-time algorithm is proved.展开更多
Developing the control of modem power converters is a very expensive and time-consuming task. Time to market can take unacceptable long. FPGA-based real-time simulation of a power stage with analog measured signals ca...Developing the control of modem power converters is a very expensive and time-consuming task. Time to market can take unacceptable long. FPGA-based real-time simulation of a power stage with analog measured signals can reduce significantly the cost and time of testing a product. This new approach is known as HIL （hardware-in-the-loop） testing. A general power converter consists of two main parts： a power level （main circuit） and a digital controller unit, which is usually realized by using some kind of DSP. Testing the controller HW and SW is quite problematic： live tests with a completely assembled converter can be dangerous and expensive. A low-power model of the main circuit can be built under laboratory conditions, but it will have parameters （e.g. time constants and relative losses） differing from the ones of the original system. The solution is the HIL simulation of the main circuit. With this method the simulator can be completely transparent for the controller unit, unlike other computer based simulation methods The subject of this paper is to develop such a real-time simulator using FPGA. The modeled circuit is a three-phase inverter, which is widely used in power converters of renewable energy sources.展开更多
AC-HVDC-AC energy conversion systems using MMC （modular multilevel converters） are becoming popular to integrate distributed energy systems to the main grid. Such multilevel converters pose a serious problems for H...AC-HVDC-AC energy conversion systems using MMC （modular multilevel converters） are becoming popular to integrate distributed energy systems to the main grid. Such multilevel converters pose a serious problems for HIL （hardware in the loop） simulators required for control, protection design and testing due to the large number of cells that must be simulated individually using very small time steps. This paper demonstrates the advantages of using a very small time step to simulate a MMC topology. The MMC is implemented on FPGA （fiel-programmable gate array） to simulate fast transient with a time step of 250 ns. The AC network and HVDC bus is simulated on the PC, with a slower time step of 10 μs to 20 μs. The simulator architecture and the components simulated on the FPGA and on the PC will be discussed, as well as the method allowing the interconnection of this slow and fast system.展开更多
This article deals with real-time hi-fi simulation of large aircraft flying in turbulent wind in a simulator to study its takeoff and landing behavior in microburst wind shear. A parameterized three-dimensional （3D）...This article deals with real-time hi-fi simulation of large aircraft flying in turbulent wind in a simulator to study its takeoff and landing behavior in microburst wind shear. A parameterized three-dimensional （3D） microburst model is built up on the basis of vortex ring and Rankine vortex principle. Complicated microburst wind fields are simulated by means of vortex ring declination and multi-vortex superposition. Based on the modeling data of Boeing 747-100, a dynamic model with wind shear effects considered is established and a general method to modify the aerodynamic model is proposed. A controller for longitudinal and lateral escapes is designed and verified in simulated microburst wind field. Results indicate that, with high extensibility, reasonability and effectiveness, the 3D microburst model with wind shear effects considered is fit to simulate real wind fields. Different escape schemes can be adopted to fly through a wind field from different locations. The model can be used for real-time flight simulation in a flight simulator.展开更多
With the development of accelerograph, strong ground motion data can be widely applied to many fields. Especially, it is an important milestone for strong motion observation to expand application fields into earthquak...With the development of accelerograph, strong ground motion data can be widely applied to many fields. Especially, it is an important milestone for strong motion observation to expand application fields into earthquake monitoring that real-time simulation of ground displacement can be obtained by strong motion records for determining three earthquake parameters. For the purpose of application, on the basis of principle of seismic response of single-degree-of-freedom (SDOF) system, this paper presents a suit of formula of simulating ground displacement records by using strong ground motion records with the help of simulator of SDOF system. The research results show that the technique is very efficient and can be widely applied to earthquake monitoring.展开更多
This paper extends the SPH method to gas simulation. The SPH （Smoothed Particles Hydrodynamics） method is the most popular method of flow simulation, which is widely used in large-scale liquid simulation. However, i...This paper extends the SPH method to gas simulation. The SPH （Smoothed Particles Hydrodynamics） method is the most popular method of flow simulation, which is widely used in large-scale liquid simulation. However, it is not found to apply to gas simulation, since those methods based on SPH can＇t be used in real-time simulation due to their enormous particles and huge computation. This paper proposes a method for gas simulation based on SPH with a small number of particles. Firstly, the method computes the position and density of each particle in each point-in-time, and outlines the shape of the simulated gas based on those particles. Secondly the method uses the grid technique to refine the shape with the diffusion of particle＇s density under the control of grid, and get more lifelike simulation result. Each grid will be assigned density according to the particles in it. The density determines the final appearance of the grid. For ensuring the natural transition of the color between adjacent grids, we give a diffuse process of density between these grids and assign appropriate values to vertexes of these grids. The experimental results show that the proposed method can give better gas simulation and meet the request of real-time.展开更多
To improve the safety of construction workers and help workers remotely control humanoid robots in construc-tion,this study designs and implements a computer vision based virtual construction simulation system.For thi...To improve the safety of construction workers and help workers remotely control humanoid robots in construc-tion,this study designs and implements a computer vision based virtual construction simulation system.For this pur-pose,human skeleton motion data are collected using a Ki-nect depth camera,and the obtained data are optimized via abnormal data elimination,smoothing,and normalization.MediaPipe extracts three-dimensional hand motion coordi-nates for accurate human posture tracking.Blender is used to build a virtual worker and site model,and the virtual worker motion is controlled based on the quaternion inverse kinematics algorithm while limiting the joint angle to en-hance the authenticity of motion simulation.Experimental results show that the system frame rate is stable at 60 frame/s,end-to-end delay is less than 20 ms,and virtual task comple-tion time is close to the real scene,verifying its engineering applicability.The proposed system can drive virtual work-ers to perform tasks and provide technical support for con-struction safety training.展开更多
A model suitable for describing the mechanical response of thin elastic objects is proposed to simulate the deformation of guide wires in minimally invasive interventions. The main objective of this simulation is to p...A model suitable for describing the mechanical response of thin elastic objects is proposed to simulate the deformation of guide wires in minimally invasive interventions. The main objective of this simulation is to provide doctors an opportunity to rehearse the surgery and select an optimal operation plan before the real surgery. In this model the guide wire is discretized with the multi-body representation and its elastic energy derivate from elastic theory is a polynomial function of the nodal displacements. The vascular structure is represented by a tetrahedron mesh extended from the triangular mesh of the artery, which can be extracted from the patient＇s CT image data. The model applies the energy decline process of the conjugate gradient method to the deformation simulation of the guide wire. Experimental results show that the polynomial relationship between elastic energy and nodal displacements tremendously simplifies the evaluation of the conjugate gradient method and significantly improves the model＇s efficiency. Compared with models depending on an explicit scheme for evaluation, the new model is not only non-conditionally stable but also more efficient. The model can be applied to the real-time simulation of guide wire in a vascular structure.展开更多
In this paper a class of real-time parallel modified Rosenbrock methods of numerical simulation is constructed for stiff dynamic systems on a multiprocessor system, and convergence and numerical stability of these met...In this paper a class of real-time parallel modified Rosenbrock methods of numerical simulation is constructed for stiff dynamic systems on a multiprocessor system, and convergence and numerical stability of these methods are discussed. A-stable real-time parallel formula of two-stage third-order and A(α)-stable real-time parallel formula with o ≈ 89.96° of three-stage fourth-order are particularly given. The numerical simulation experiments in parallel environment show that the class of algorithms is efficient and applicable, with greater speedup.展开更多
The electric vehicle(EV)charging station is a critical part of the infrastructure for the wide adoption of EVs.Realtime simulation of an EV station plays an essential role in testing its operation under different oper...The electric vehicle(EV)charging station is a critical part of the infrastructure for the wide adoption of EVs.Realtime simulation of an EV station plays an essential role in testing its operation under different operating modes.However,the large numbers of high-frequency power electronic switches contained in EV chargers pose great challenges for real-time simulation.This paper proposes a compact electromagnetic transient program(C-EMTP)algorithm for FPGA-based real-time simulation of an EV station with multiple high-frequency chargers.The C-EMTP algorithm transforms the traditional EMTP algorithm into two parallel sub-tasks only consisting of simple matrix operations,to fully utilize the high parallelism of FPGA.The simulation time step can be greatly reduced compared with that of the traditional EMTP algorithm,and so the simulation accuracy for high-frequency power electronics is improved.The EV chargers can be decoupled with each other and simulated in parallel.A CPU-FPGA-based realtime simulation platform is developed and the proposed simulation of the EV station is implemented.The control strategy is simulated in a CPU with 100μs time-step,while the EV station circuit topology is simulated in a single FPGA with a 250 ns time-step.In the case studies,the EV station consists of a two-level rectifier and five dual-active bridge(DAB)EV chargers.It is tested under different scenarios,and the real-time simulation results are validated using PSCAD/EMTDC.展开更多
Virtual reality-based surgery simulation is becoming popular with the development of minimally invasive abdominal surgery,where deformable soft tissue is modelled and simulated.The mass-spring model(MSM)and finite ele...Virtual reality-based surgery simulation is becoming popular with the development of minimally invasive abdominal surgery,where deformable soft tissue is modelled and simulated.The mass-spring model(MSM)and finite element method(FEM)are common methods used in the simulation of soft tissue deformation.However,MSM has an issue concerning accuracy,while FEM has a problem with efficiency.To achieve higher accuracy and efficiency at the same time,we applied a co-rotational FEM in the simulation of a kidney with a tumour inside,achieving a real-time and accurate deformation simulation.In addition,we set a multi-model representation for mechanical simulation and visual rendering.The implicit Euler method and conjugate gradient method were adopted for setting and solving the linear system.For a realistic simulation of surgery,constraints outside the kidney and between the kidney and tumour were set with two series of mechanical properties for the two models.Experiments were conducted to validate the accuracy and real-time performance.展开更多
An environment control and life support system（ECLSS） is an important system in a space station. The ECLSS is a typical complex system, and the real-time simulation technology can help to accelerate its research pro...An environment control and life support system（ECLSS） is an important system in a space station. The ECLSS is a typical complex system, and the real-time simulation technology can help to accelerate its research process by using distributed hardware in a loop simulation system. An implicit fixed time step numerical integration method is recommended for a real-time simulation system with time-varying parameters. However, its computational efficiency is too low to satisfy the real-time data interaction, especially for the complex ECLSS system running on a PC cluster. The instability problem of an explicit method strongly limits its application in the ECLSS real-time simulation although it has a high computational efficiency. This paper proposes an improved numerical simulation method to overcome the instability problem based on the explicit Euler method. A temperature and humidity control subsystem（THCS） is firstly established, and its numerical stability is analyzed by using the eigenvalue estimation theory. Furthermore, an adaptive operator is proposed to avoid the potential instability problem. The stability and accuracy of the proposed method are investigated carefully. Simulation results show that this proposed method can provide a good way for some complex time-variant systems to run their real-time simulation on a PC cluster.展开更多
In this paper parallel Rosenbrock methods in real-time simulation are presented on parallel computers. Their construction, their convergence and their numerical stability are studied, and the numerical simulation expe...In this paper parallel Rosenbrock methods in real-time simulation are presented on parallel computers. Their construction, their convergence and their numerical stability are studied, and the numerical simulation experiments are conducted on a personal computer and a parallel computer respectively. [ABSTRACT FROM AUTHOR]展开更多
Recently, real-time simulation of renewable energy sources are indispensible for evaluating the performance of the maximum power point tracking （MPPT） controller, especially in the photovoltaic （PV） system in orde...Recently, real-time simulation of renewable energy sources are indispensible for evaluating the performance of the maximum power point tracking （MPPT） controller, especially in the photovoltaic （PV） system in order to reduce cost in the testing phase. Nowadays, real time PV simulators are obtained by using analog and/or digital components. In this paper, a real-time simulation of a PV system with a boost converter was proposed using only the digital signal processor （DSP） processor with two DC voltage sources to emulate the temperature and irradiation in the PV system. A MATLAB/ Simulink environment was used to develop the real-time PV system with a boost converter into a C-program and build it into a DSP controller TMS320F28335. Besides, the performance of the real-time DSP-based PV was tested in different temperature and irradiation conditions to observe the P-V and V-I characteristics. Further, the performance of the PV with a boost converter was tested at different temperatures and irradiations using MPPT algorithms. This scheme was tested through simulation and the results were validated with that of standard conditions given in the PV data sheets. Implementation of this project helped to attract more researchers to study renewable energy applications without real sources. This might facilitate the study of PV systems in a real-time scenario and the evaluation of what should be expected for PV modules available in the market.展开更多
In order to study the interaction among the traction power supply,the train group and the operation dispatching of urban rail transit,a coupling simulation system of power supply system,trains and dispatching manageme...In order to study the interaction among the traction power supply,the train group and the operation dispatching of urban rail transit,a coupling simulation system of power supply system,trains and dispatching management is constructed.In order to solve the problems of different timescales and difficult cooperation operation for related subsystems,a multi-bus distributed real-time network architecture based on hierarchical management of communication data is established,and simulation management software is developed to facilitate the free expansion of the simulation system.Meanwhile,the track line,train operation and other large timescale subsystems are realized by the pure digital simulation.And the time-sensitive subsystems,such as train traction system,braking system,auxiliary power supply system and network system etc.,are built by the semi-physical simulation.In this article,the system structure and the main implementation principle of each simulation subsystem are given in detail,and the system is tested and verified at the end.The results show that the simulation system can meet the expected requirements.展开更多
As an important autumn feature,scenes with large numbers of falling leaves are common in movies and games. However,it is a challenge for computer graphics to simulate such scenes in an authentic and efficient manner. ...As an important autumn feature,scenes with large numbers of falling leaves are common in movies and games. However,it is a challenge for computer graphics to simulate such scenes in an authentic and efficient manner. This paper proposes a GPU based approach for simulating the falling motion of many leaves in real time. Firstly,we use a motionsynthesis based method to analyze the falling motion of the leaves,which enables us to describe complex falling trajectories using low-dimensional features. Secondly,we transmit a primitive-motion trajectory dataset together with the low-dimensional features of the falling leaves to video memory,allowing us to execute the appropriate calculations on the GPU.展开更多
Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
BACKGROUND Orthopaedic surgical education has traditionally depended on the apprenticeship model of“see one,do one,teach one”.However,reduced operative exposure,stricter work-hour regulations,medicolegal constraints...BACKGROUND Orthopaedic surgical education has traditionally depended on the apprenticeship model of“see one,do one,teach one”.However,reduced operative exposure,stricter work-hour regulations,medicolegal constraints,and patient safety concerns have constrained its practicality.Simulation-based training has become a reliable,safe,and cost-efficient alternative.Dry lab techniques,especially virtual and augmented reality,make up 78%of current dry lab research,whereas wet labs still set the standard for anatomical realism.AIM To evaluate the effectiveness,limitations,and future directions of wet and dry lab simulation in orthopaedic training.METHODS A scoping review was carried out across four databases-PubMed,Cochrane Library,Web of Science,and EBSCOhost-up to 2025.Medical Subject Headings included:"Orthopaedic Education","Wet Lab","Dry Lab","Simulation Training","Virtual Reality",and"Surgical Procedure".Eligible studies focused on orthopaedic or spinal surgical education,employed wet or dry lab techniques,and assessed training effectiveness.Exclusion criteria consisted of non-English publications,abstracts only,non-orthopaedic research,and studies unrelated to simulation.Two reviewers independently screened titles,abstracts,and full texts,resolving discrepancies with a third reviewer.RESULTS From 1851 records,101 studies met inclusion:78 on dry labs,7 on wet labs,4 on both.Virtual reality(VR)simulations were most common,with AI increasingly used for feedback and assessment.Cadaveric training remains the gold standard for accuracy and tactile feedback,while dry labs-especially VR-offer scalability,lower cost(40%-60%savings in five studies),and accessibility for novices.Senior residents prefer wet labs for complex tasks;juniors favour dry labs for basics.Challenges include limited transferability data,lack of standard outcome metrics,and ethical concerns about cadaver use and AI assessment.CONCLUSION Wet and dry labs each have unique strengths in orthopaedic training.A hybrid approach combining both,supported by standardised assessments and outcome studies,is most effective.Future efforts should aim for uniform reporting,integrating new technologies,and policy support for hybrid curricula to enhance skills and patient care.展开更多
Real-time hybrid simulation is an efficient and cost-effective dynamic testing technique for performance evaluation of structural systems subjected to earthquake loading with rate-dependent behavior. A loading assembl...Real-time hybrid simulation is an efficient and cost-effective dynamic testing technique for performance evaluation of structural systems subjected to earthquake loading with rate-dependent behavior. A loading assembly with multiple actuators is required to impose realistic boundary conditions on physical specimens. However, such a testing system is expected to exhibit significant dynamic coupling of the actuators and suffer from time lags that are associated with the dynamics of the servo-hydraulic system, as well as control-structure interaction （CSI）. One approach to reducing experimental errors considers a multi-input, multi-output （MIMO） controller design, yielding accurate reference tracking and noise rejection. In this paper, a framework for multi-axial real-time hybrid simulation （maRTHS） testing is presented. The methodology employs a real-time feedback-feedforward controller for multiple actuators commanded in Cartesian coordinates. Kinematic transformations between actuator space and Cartesian space are derived for all six-degrees-of- freedom of the moving platform. Then, a frequency domain identification technique is used to develop an accurate MIMO transfer function of the system. Further, a Cartesian-domain model-based feedforward-feedback controller is implemented for time lag compensation and to increase the robustness of the reference tracking for given model uncertainty. The framework is implemented using the 1/5th-scale Load and Boundary Condition Box （LBCB） located at the University of Illinois at Urbana- Champaign. To demonstrate the efficacy of the proposed methodology, a single-story frame subjected to earthquake loading is tested. One of the columns in the fraane is represented physically in the laboratory as a cantilevered steel column. For real- time execution, the numerical substructure, kinematic transformations, and controllers are implemented on a digital signal processor. Results show excellent performance of the maRTHS framework when six-degrees-of-freedom are controUed at the interface between substructures.展开更多
文摘A class of hybrid algorithms of real-time simulation based on evaluation of non-integerstep right-hand side function are presented in this paper. And some results of the convergence and stability of the algorithms are given. Using the class of algorithms, evaluation for the right-hand side function is needed once in every integration-step. Moreover, comparing with the other methods with the same amount of work, their numerical stability regions are larger and the method errors are smaller, and the numerical experiments show that the algorithms are very effective.
文摘In this paper, a mathematical model of real-time simulation is given, and the problem of convergence on real-time Runge-Kutta algorithms is analysed. At last a theorem on the relation between the order of compensation and the convergent order of real-time algorithm is proved.
文摘Developing the control of modem power converters is a very expensive and time-consuming task. Time to market can take unacceptable long. FPGA-based real-time simulation of a power stage with analog measured signals can reduce significantly the cost and time of testing a product. This new approach is known as HIL （hardware-in-the-loop） testing. A general power converter consists of two main parts： a power level （main circuit） and a digital controller unit, which is usually realized by using some kind of DSP. Testing the controller HW and SW is quite problematic： live tests with a completely assembled converter can be dangerous and expensive. A low-power model of the main circuit can be built under laboratory conditions, but it will have parameters （e.g. time constants and relative losses） differing from the ones of the original system. The solution is the HIL simulation of the main circuit. With this method the simulator can be completely transparent for the controller unit, unlike other computer based simulation methods The subject of this paper is to develop such a real-time simulator using FPGA. The modeled circuit is a three-phase inverter, which is widely used in power converters of renewable energy sources.
文摘AC-HVDC-AC energy conversion systems using MMC （modular multilevel converters） are becoming popular to integrate distributed energy systems to the main grid. Such multilevel converters pose a serious problems for HIL （hardware in the loop） simulators required for control, protection design and testing due to the large number of cells that must be simulated individually using very small time steps. This paper demonstrates the advantages of using a very small time step to simulate a MMC topology. The MMC is implemented on FPGA （fiel-programmable gate array） to simulate fast transient with a time step of 250 ns. The AC network and HVDC bus is simulated on the PC, with a slower time step of 10 μs to 20 μs. The simulator architecture and the components simulated on the FPGA and on the PC will be discussed, as well as the method allowing the interconnection of this slow and fast system.
基金Foundation item： Program of National Natural Science Foundation of China and The Civil Aviation （60776812）
文摘This article deals with real-time hi-fi simulation of large aircraft flying in turbulent wind in a simulator to study its takeoff and landing behavior in microburst wind shear. A parameterized three-dimensional （3D） microburst model is built up on the basis of vortex ring and Rankine vortex principle. Complicated microburst wind fields are simulated by means of vortex ring declination and multi-vortex superposition. Based on the modeling data of Boeing 747-100, a dynamic model with wind shear effects considered is established and a general method to modify the aerodynamic model is proposed. A controller for longitudinal and lateral escapes is designed and verified in simulated microburst wind field. Results indicate that, with high extensibility, reasonability and effectiveness, the 3D microburst model with wind shear effects considered is fit to simulate real wind fields. Different escape schemes can be adopted to fly through a wind field from different locations. The model can be used for real-time flight simulation in a flight simulator.
基金National Nature Science Foundation of China (50378086) Commonweal Foundation of the Ministry of Science and+1 种基金Technology (2003DIB2J099) key project of China EarthquakeAdministrationduring the tenth Five-year Plan.
文摘With the development of accelerograph, strong ground motion data can be widely applied to many fields. Especially, it is an important milestone for strong motion observation to expand application fields into earthquake monitoring that real-time simulation of ground displacement can be obtained by strong motion records for determining three earthquake parameters. For the purpose of application, on the basis of principle of seismic response of single-degree-of-freedom (SDOF) system, this paper presents a suit of formula of simulating ground displacement records by using strong ground motion records with the help of simulator of SDOF system. The research results show that the technique is very efficient and can be widely applied to earthquake monitoring.
基金Supported by National Natural Science Foundation of China(No.61272024)
文摘This paper extends the SPH method to gas simulation. The SPH （Smoothed Particles Hydrodynamics） method is the most popular method of flow simulation, which is widely used in large-scale liquid simulation. However, it is not found to apply to gas simulation, since those methods based on SPH can＇t be used in real-time simulation due to their enormous particles and huge computation. This paper proposes a method for gas simulation based on SPH with a small number of particles. Firstly, the method computes the position and density of each particle in each point-in-time, and outlines the shape of the simulated gas based on those particles. Secondly the method uses the grid technique to refine the shape with the diffusion of particle＇s density under the control of grid, and get more lifelike simulation result. Each grid will be assigned density according to the particles in it. The density determines the final appearance of the grid. For ensuring the natural transition of the color between adjacent grids, we give a diffuse process of density between these grids and assign appropriate values to vertexes of these grids. The experimental results show that the proposed method can give better gas simulation and meet the request of real-time.
基金The Eighth National “Ten Thousand Talents Plan for Top Young Talents” of Chinathe National Natural Science Foundation of China (No. 52478117, 52378120)。
文摘To improve the safety of construction workers and help workers remotely control humanoid robots in construc-tion,this study designs and implements a computer vision based virtual construction simulation system.For this pur-pose,human skeleton motion data are collected using a Ki-nect depth camera,and the obtained data are optimized via abnormal data elimination,smoothing,and normalization.MediaPipe extracts three-dimensional hand motion coordi-nates for accurate human posture tracking.Blender is used to build a virtual worker and site model,and the virtual worker motion is controlled based on the quaternion inverse kinematics algorithm while limiting the joint angle to en-hance the authenticity of motion simulation.Experimental results show that the system frame rate is stable at 60 frame/s,end-to-end delay is less than 20 ms,and virtual task comple-tion time is close to the real scene,verifying its engineering applicability.The proposed system can drive virtual work-ers to perform tasks and provide technical support for con-struction safety training.
文摘A model suitable for describing the mechanical response of thin elastic objects is proposed to simulate the deformation of guide wires in minimally invasive interventions. The main objective of this simulation is to provide doctors an opportunity to rehearse the surgery and select an optimal operation plan before the real surgery. In this model the guide wire is discretized with the multi-body representation and its elastic energy derivate from elastic theory is a polynomial function of the nodal displacements. The vascular structure is represented by a tetrahedron mesh extended from the triangular mesh of the artery, which can be extracted from the patient＇s CT image data. The model applies the energy decline process of the conjugate gradient method to the deformation simulation of the guide wire. Experimental results show that the polynomial relationship between elastic energy and nodal displacements tremendously simplifies the evaluation of the conjugate gradient method and significantly improves the model＇s efficiency. Compared with models depending on an explicit scheme for evaluation, the new model is not only non-conditionally stable but also more efficient. The model can be applied to the real-time simulation of guide wire in a vascular structure.
基金This project was supported by the National Natural Science Foundation of China (No. 19871080).
文摘In this paper a class of real-time parallel modified Rosenbrock methods of numerical simulation is constructed for stiff dynamic systems on a multiprocessor system, and convergence and numerical stability of these methods are discussed. A-stable real-time parallel formula of two-stage third-order and A(α)-stable real-time parallel formula with o ≈ 89.96° of three-stage fourth-order are particularly given. The numerical simulation experiments in parallel environment show that the class of algorithms is efficient and applicable, with greater speedup.
基金supported by China Postdoctoral Science Foundation(BX20200221,2020 M671122)National Key Research and Development Program of China(2019YFE012784)National Natural Science Foundation of China(51877133).
文摘The electric vehicle(EV)charging station is a critical part of the infrastructure for the wide adoption of EVs.Realtime simulation of an EV station plays an essential role in testing its operation under different operating modes.However,the large numbers of high-frequency power electronic switches contained in EV chargers pose great challenges for real-time simulation.This paper proposes a compact electromagnetic transient program(C-EMTP)algorithm for FPGA-based real-time simulation of an EV station with multiple high-frequency chargers.The C-EMTP algorithm transforms the traditional EMTP algorithm into two parallel sub-tasks only consisting of simple matrix operations,to fully utilize the high parallelism of FPGA.The simulation time step can be greatly reduced compared with that of the traditional EMTP algorithm,and so the simulation accuracy for high-frequency power electronics is improved.The EV chargers can be decoupled with each other and simulated in parallel.A CPU-FPGA-based realtime simulation platform is developed and the proposed simulation of the EV station is implemented.The control strategy is simulated in a CPU with 100μs time-step,while the EV station circuit topology is simulated in a single FPGA with a 250 ns time-step.In the case studies,the EV station consists of a two-level rectifier and five dual-active bridge(DAB)EV chargers.It is tested under different scenarios,and the real-time simulation results are validated using PSCAD/EMTDC.
基金the National Key Research and Development Program of China(No.2017YFB1302900)the National Natural Science Foundation of China(Nos.81971709,M-0019,and 82011530141)+2 种基金the Foundation of Science and Technology Commission of Shanghai Municipality(Nos.19510712200,and 20490740700)the Shanghai Jiao Tong University Foundation on Medical and Technological Joint Science Research(Nos.ZH2018ZDA15,YG2019ZDA06,and ZH2018QNA23)the 2020 Key Research Project of Xiamen Municipal Government(No.3502Z20201030)。
文摘Virtual reality-based surgery simulation is becoming popular with the development of minimally invasive abdominal surgery,where deformable soft tissue is modelled and simulated.The mass-spring model(MSM)and finite element method(FEM)are common methods used in the simulation of soft tissue deformation.However,MSM has an issue concerning accuracy,while FEM has a problem with efficiency.To achieve higher accuracy and efficiency at the same time,we applied a co-rotational FEM in the simulation of a kidney with a tumour inside,achieving a real-time and accurate deformation simulation.In addition,we set a multi-model representation for mechanical simulation and visual rendering.The implicit Euler method and conjugate gradient method were adopted for setting and solving the linear system.For a realistic simulation of surgery,constraints outside the kidney and between the kidney and tumour were set with two series of mechanical properties for the two models.Experiments were conducted to validate the accuracy and real-time performance.
基金supported by the Aeronautical Science Foundation of China(No.2014ZC09002)
文摘An environment control and life support system（ECLSS） is an important system in a space station. The ECLSS is a typical complex system, and the real-time simulation technology can help to accelerate its research process by using distributed hardware in a loop simulation system. An implicit fixed time step numerical integration method is recommended for a real-time simulation system with time-varying parameters. However, its computational efficiency is too low to satisfy the real-time data interaction, especially for the complex ECLSS system running on a PC cluster. The instability problem of an explicit method strongly limits its application in the ECLSS real-time simulation although it has a high computational efficiency. This paper proposes an improved numerical simulation method to overcome the instability problem based on the explicit Euler method. A temperature and humidity control subsystem（THCS） is firstly established, and its numerical stability is analyzed by using the eigenvalue estimation theory. Furthermore, an adaptive operator is proposed to avoid the potential instability problem. The stability and accuracy of the proposed method are investigated carefully. Simulation results show that this proposed method can provide a good way for some complex time-variant systems to run their real-time simulation on a PC cluster.
文摘In this paper parallel Rosenbrock methods in real-time simulation are presented on parallel computers. Their construction, their convergence and their numerical stability are studied, and the numerical simulation experiments are conducted on a personal computer and a parallel computer respectively. [ABSTRACT FROM AUTHOR]
文摘Recently, real-time simulation of renewable energy sources are indispensible for evaluating the performance of the maximum power point tracking （MPPT） controller, especially in the photovoltaic （PV） system in order to reduce cost in the testing phase. Nowadays, real time PV simulators are obtained by using analog and/or digital components. In this paper, a real-time simulation of a PV system with a boost converter was proposed using only the digital signal processor （DSP） processor with two DC voltage sources to emulate the temperature and irradiation in the PV system. A MATLAB/ Simulink environment was used to develop the real-time PV system with a boost converter into a C-program and build it into a DSP controller TMS320F28335. Besides, the performance of the real-time DSP-based PV was tested in different temperature and irradiation conditions to observe the P-V and V-I characteristics. Further, the performance of the PV with a boost converter was tested at different temperatures and irradiations using MPPT algorithms. This scheme was tested through simulation and the results were validated with that of standard conditions given in the PV data sheets. Implementation of this project helped to attract more researchers to study renewable energy applications without real sources. This might facilitate the study of PV systems in a real-time scenario and the evaluation of what should be expected for PV modules available in the market.
文摘In order to study the interaction among the traction power supply,the train group and the operation dispatching of urban rail transit,a coupling simulation system of power supply system,trains and dispatching management is constructed.In order to solve the problems of different timescales and difficult cooperation operation for related subsystems,a multi-bus distributed real-time network architecture based on hierarchical management of communication data is established,and simulation management software is developed to facilitate the free expansion of the simulation system.Meanwhile,the track line,train operation and other large timescale subsystems are realized by the pure digital simulation.And the time-sensitive subsystems,such as train traction system,braking system,auxiliary power supply system and network system etc.,are built by the semi-physical simulation.In this article,the system structure and the main implementation principle of each simulation subsystem are given in detail,and the system is tested and verified at the end.The results show that the simulation system can meet the expected requirements.
基金supported by National High-tech Research and Development Program of China(No.2013AA013903)
文摘As an important autumn feature,scenes with large numbers of falling leaves are common in movies and games. However,it is a challenge for computer graphics to simulate such scenes in an authentic and efficient manner. This paper proposes a GPU based approach for simulating the falling motion of many leaves in real time. Firstly,we use a motionsynthesis based method to analyze the falling motion of the leaves,which enables us to describe complex falling trajectories using low-dimensional features. Secondly,we transmit a primitive-motion trajectory dataset together with the low-dimensional features of the falling leaves to video memory,allowing us to execute the appropriate calculations on the GPU.
基金National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
文摘BACKGROUND Orthopaedic surgical education has traditionally depended on the apprenticeship model of“see one,do one,teach one”.However,reduced operative exposure,stricter work-hour regulations,medicolegal constraints,and patient safety concerns have constrained its practicality.Simulation-based training has become a reliable,safe,and cost-efficient alternative.Dry lab techniques,especially virtual and augmented reality,make up 78%of current dry lab research,whereas wet labs still set the standard for anatomical realism.AIM To evaluate the effectiveness,limitations,and future directions of wet and dry lab simulation in orthopaedic training.METHODS A scoping review was carried out across four databases-PubMed,Cochrane Library,Web of Science,and EBSCOhost-up to 2025.Medical Subject Headings included:"Orthopaedic Education","Wet Lab","Dry Lab","Simulation Training","Virtual Reality",and"Surgical Procedure".Eligible studies focused on orthopaedic or spinal surgical education,employed wet or dry lab techniques,and assessed training effectiveness.Exclusion criteria consisted of non-English publications,abstracts only,non-orthopaedic research,and studies unrelated to simulation.Two reviewers independently screened titles,abstracts,and full texts,resolving discrepancies with a third reviewer.RESULTS From 1851 records,101 studies met inclusion:78 on dry labs,7 on wet labs,4 on both.Virtual reality(VR)simulations were most common,with AI increasingly used for feedback and assessment.Cadaveric training remains the gold standard for accuracy and tactile feedback,while dry labs-especially VR-offer scalability,lower cost(40%-60%savings in five studies),and accessibility for novices.Senior residents prefer wet labs for complex tasks;juniors favour dry labs for basics.Challenges include limited transferability data,lack of standard outcome metrics,and ethical concerns about cadaver use and AI assessment.CONCLUSION Wet and dry labs each have unique strengths in orthopaedic training.A hybrid approach combining both,supported by standardised assessments and outcome studies,is most effective.Future efforts should aim for uniform reporting,integrating new technologies,and policy support for hybrid curricula to enhance skills and patient care.
基金CONICYT-Chile through Becas Chile Scholarship under Grant No.72140204Universidad Tecnica Federico Santa Maria(Chile)through Faculty Development Scholarship under Grant No.208-13
文摘Real-time hybrid simulation is an efficient and cost-effective dynamic testing technique for performance evaluation of structural systems subjected to earthquake loading with rate-dependent behavior. A loading assembly with multiple actuators is required to impose realistic boundary conditions on physical specimens. However, such a testing system is expected to exhibit significant dynamic coupling of the actuators and suffer from time lags that are associated with the dynamics of the servo-hydraulic system, as well as control-structure interaction （CSI）. One approach to reducing experimental errors considers a multi-input, multi-output （MIMO） controller design, yielding accurate reference tracking and noise rejection. In this paper, a framework for multi-axial real-time hybrid simulation （maRTHS） testing is presented. The methodology employs a real-time feedback-feedforward controller for multiple actuators commanded in Cartesian coordinates. Kinematic transformations between actuator space and Cartesian space are derived for all six-degrees-of- freedom of the moving platform. Then, a frequency domain identification technique is used to develop an accurate MIMO transfer function of the system. Further, a Cartesian-domain model-based feedforward-feedback controller is implemented for time lag compensation and to increase the robustness of the reference tracking for given model uncertainty. The framework is implemented using the 1/5th-scale Load and Boundary Condition Box （LBCB） located at the University of Illinois at Urbana- Champaign. To demonstrate the efficacy of the proposed methodology, a single-story frame subjected to earthquake loading is tested. One of the columns in the fraane is represented physically in the laboratory as a cantilevered steel column. For real- time execution, the numerical substructure, kinematic transformations, and controllers are implemented on a digital signal processor. Results show excellent performance of the maRTHS framework when six-degrees-of-freedom are controUed at the interface between substructures.
