Objective:To analyze the effectiveness of an integrated teaching platform combining virtual reality(VR)technology and high-end simulators in practical obstetrics and gynecology teaching.Methods:A total of 39 interns w...Objective:To analyze the effectiveness of an integrated teaching platform combining virtual reality(VR)technology and high-end simulators in practical obstetrics and gynecology teaching.Methods:A total of 39 interns who underwent obstetrics and gynecology internships from March 2023 to March 2024 were included in the reference group and received conventional practical teaching methods.Another 39 interns who underwent internships from April 2024 to April 2025 were included in the observation group and received the integrated teaching platform combining VR and high-end simulators.The teaching effects of the two groups were compared.Results:The observation group achieved higher assessment scores than the reference group,with higher scores in self-directed learning ability and clinical thinking ability after teaching,as well as higher teaching satisfaction(p<0.05).Conclusion:The integrated teaching platform combining VR and high-end simulators can improve the assessment scores of obstetrics and gynecology interns,cultivate their self-directed learning ability and clinical thinking ability,and achieve high teaching satisfaction.展开更多
The use of simulators as educational tools for medical procedures is spreading rapidly and many efforts have been made for their implementation in gastrointestinal endoscopy training. Endoscopy simulation training has...The use of simulators as educational tools for medical procedures is spreading rapidly and many efforts have been made for their implementation in gastrointestinal endoscopy training. Endoscopy simulation training has been suggested for ascertaining patient safety while positively influencing the trainees' learning curve. Virtual simulators are the most promising tool among all available types of simulators. These integrated modalities offer a human-like endoscopy experience by combining virtual images of the gastrointestinal tract and haptic realism with using a customized endoscope. From their first steps in the 1980s until today, research involving virtual endoscopic simulators can be divided in two categories: investigation of the impact of virtual simulator training in acquiring endoscopy skills and measuring competence. Emphasis should also be given to the financial impact of their implementation in endoscopy, including the cost of these state-of-theart simulators and the potential economic benefits from their usage. Advances in technology will contribute to the upgrade of existing models and the development of new ones; while further research should be carried out to discover new fields of application.展开更多
The International Maritime Organization (IMO) has encouraged its member countries to introduce Formal Safety Assessment (FSA) for ship operations since the end of the last century. FSA can be used through certain form...The International Maritime Organization (IMO) has encouraged its member countries to introduce Formal Safety Assessment (FSA) for ship operations since the end of the last century. FSA can be used through certain formal assessing steps to generate effective recommendations and cautions to control marine risks and improve the safety of ships. On the basis of the brief introduction of FSA, this paper describes the ideas of applying FSA to the prevention of human error in ship operations. It especially discusses the investigation and analysis of the information and data using navigation simulators and puts forward some suggestions for the introduction and development of the FSA research work for safer ship operations.展开更多
Objective: To explore the effectiveness of applying patient simulators combined with Internet Plus scenario simulation teaching models on intravenous (IV) infusion nursing education, and to provide scientific evidence...Objective: To explore the effectiveness of applying patient simulators combined with Internet Plus scenario simulation teaching models on intravenous (IV) infusion nursing education, and to provide scientific evidence for the implementation of advanced teaching models in future nursing education. Methods: Enrolled 60 nurses who took the IV infusion therapy training program in our hospital from January 2022 to December 2023 for research. 30 nurses who were trained in traditional teaching models from January to December 2022 were selected as the control group, and 30 nurses who were trained with simulation-based teaching models with methods including simulated patients, internet, online meetings which can be replayed and scenario simulation, etc. from January to December 2023 were selected as the experimental group. Evaluated the learning outcomes based on the Competency Inventory for Nursing Students (CINS), Problem-Solving Inventory (PSI), comprehensive learning ability, scientific research ability, and proficiency in the theoretical knowledge and practical skills of IV infusion therapy. Nursing quality, the incidence of IV infusion therapy complications and nurse satisfaction with different teaching models were also measured. Results: The scientific research ability, PSI scores, CINS scores, and comprehensive learning ability of the experimental group were better than those of the control group (P 0.05), and their assessment results of practical skills, nursing quality of IV infusion therapy during training, and satisfaction with teaching models were all better than those of the control group with statistical significance (P < 0.05). The incidence of IV infusion therapy complications in the experimental group was lower than that in the control group, indicating statistical significance (P < 0.05). Conclusions: Teaching models based on patient simulators combined with Internet Plus scenario simulation enable nursing students to learn more directly and practice at any time and in any place, and can improve their proficiency in IV infusion theoretical knowledge and skills (e.g. PICC catheterization), core competencies, problem-solving ability, comprehensive learning ability, scientific research ability and the ability to deal with complicated cases. Also, it helps provide high-quality nursing education, improve the nursing quality of IV therapy, reduce the incidence of related complications, and ensure the safety of patients with IV therapy.展开更多
The advantages of a flat-panel X-ray source(FPXS)make it a promising candidate for imaging applications.Accurate imaging-system modeling and projection simulation are critical for analyzing imaging performance and res...The advantages of a flat-panel X-ray source(FPXS)make it a promising candidate for imaging applications.Accurate imaging-system modeling and projection simulation are critical for analyzing imaging performance and resolving overlapping projection issues in FPXS.The conventional analytical ray-tracing approach is limited by the number of patterns and is not applicable to FPXS-projection calculations.However,the computation time of Monte Carlo(MC)simulation is independent of the size of the patterned arrays in FPXS.This study proposes two high-efficiency MC projection simulators for FPXS:a graphics processing unit(GPU)-based phase-space sampling MC(gPSMC)simulator and GPU-based fluence sampling MC(gFSMC)simulator.The two simulators comprise three components:imaging-system modeling,photon initialization,and physical-interaction simulations in the phantom.Imaging-system modeling was performed by modeling the FPXS,imaging geometry,and detector.The gPSMC simulator samples the initial photons from the phase space,whereas the gFSMC simulator performs photon initialization from the calculated energy spectrum and fluence map.The entire process of photon interaction with the geometry and arrival at the detector was simulated in parallel using multiple GPU kernels,and projections based on the two simulators were calculated.The accuracies of the two simulators were evaluated by comparing them with the conventional analytical ray-tracing approach and acquired projections,and the efficiencies were evaluated by comparing the computation time.The results of simulated and realistic experiments illustrate the accuracy and efficiency of the proposed gPSMC and gFSMC simulators in the projection calculation of various phantoms.展开更多
Background This paper shows how current collaborative virtual environments(VEs)such as Mozilla Hubs and AltspaceVR can aid in the task of requirements gathering in VR for simulation and training.Methods We performed a...Background This paper shows how current collaborative virtual environments(VEs)such as Mozilla Hubs and AltspaceVR can aid in the task of requirements gathering in VR for simulation and training.Methods We performed a qualitative study on our use of these technologies in the requirements gathering of two projects.Results Our results show that requirements gathering in virtual reality has an impact on the process of requirements identification.We report advantages and shortcomings that will be of interest to future practitioners.For example,we found that VR sessions for requirements gathering in current VEs could benefit from better pointers and better sound quality.Conclusion Current VEs are useful for the requirements gathering task in the development of VR simulators and VR training environments.展开更多
This article describes numerical simulation of gas pipeline network operation using high-accuracy computational fluid dynamics (CFD) simulators of the modes of gas mixture transmission through long, multi-line pipelin...This article describes numerical simulation of gas pipeline network operation using high-accuracy computational fluid dynamics (CFD) simulators of the modes of gas mixture transmission through long, multi-line pipeline systems (CFD-simulator). The approach used in CFD-simulators for modeling gas mixture transmission through long, branched, multi-section pipelines is based on tailoring the full system of fluid dynamics equations to conditions of unsteady, non-isothermal processes of the gas mixture flow. Identification, in a CFD-simulator, of safe parameters for gas transmission through compressor stations amounts to finding the interior points of admissible sets described by systems of nonlinear algebraic equalities and inequalities. Such systems of equalities and inequalities comprise a formal statement of technological, design, operational and other constraints to which operation of the network equipment is subject. To illustrate the practicability of the method of numerical simulation of a gas transmission network, we compare computation results and gas flow parameters measured on-site at the gas transmission enter-prise.展开更多
In this paper, we consider a novel two-dimensional(2D) geometry-based stochastic model(GBSM) for multiple-input multiple-output(MIMO) vehicle-to-vehicle(V2V) wideband fading channels. The proposed model employs the co...In this paper, we consider a novel two-dimensional(2D) geometry-based stochastic model(GBSM) for multiple-input multiple-output(MIMO) vehicle-to-vehicle(V2V) wideband fading channels. The proposed model employs the combination of a two-ring model and a multiple confocal ellipses model, where the signal is sum of the line-of-sight(Lo S) component, single-bounced(SB) rays, and double-bounced(DB) rays. Based on the reference model, we derive some expressions of channel statistical properties, including space-time correlation function(STCF), Doppler spectral power density(DPSD), envelope level crossing rate(LCR) and average fade duration(AFD). In addition, corresponding deterministic and stochastic simulation models are developed based on the reference model. Moreover, we compare the statistical properties of the reference model and the two simulation models in different scenarios and investigate the impact of different vehicular traffic densities(VTDs) on the channel statistical properties of the proposed model. Finally, the great agreement between simulation models and the reference model demonstrates not only the utility of simulation models, but also the correctness of theoretical derivations and simulations.展开更多
A critical challenge of any blast simulation facility is in producing the widest possible pressure-impulse range for matching against equivalent high-explosive events.Shock tubes and blast simulators are often constra...A critical challenge of any blast simulation facility is in producing the widest possible pressure-impulse range for matching against equivalent high-explosive events.Shock tubes and blast simulators are often constrained with the lack of effective ways to control blast wave profiles and as a result have a limited performance range.Some wave shaping techniques employed in some facilities are reviewed but often necessitate extensive geometric modifications,inadvertently cause flow anomalies,and/or are only applicable under very specific configurations.This paper investigates controlled venting as an expedient way for waveforms to be tuned without requiring extensive modifications to the driver or existing geometry and could be widely applied by existing and future blast simulation and shock tube facilities.The use of controlled venting is demonstrated experimentally using the Advanced Blast Simulator(shock tube)at the Australian National Facility of Physical Blast Simulation and via numerical flow simulations with Computational Fluid Dynamics.Controlled venting is determined as an effective method for mitigating the impact of re-reflected waves within the blast simulator.This control method also allows for the adjustment of parameters such as tuning the peak overpressure,the positive phase duration,and modifying the magnitude of the negative phase and the secondary shock of the blast waves.This paper is concluded with an illustration of the potential expanded performance range of the Australian blast simulation facility when controlled venting for blast waveform tailoring as presented in this paper is applied.展开更多
A practical survey on engineering implementation of flight control laws on helicopter engineering simulators is proposed.Advances of helicopter engineering simulators are introduced.Practical flight control technologi...A practical survey on engineering implementation of flight control laws on helicopter engineering simulators is proposed.Advances of helicopter engineering simulators are introduced.Practical flight control technologies are reviewed,with an emphasis on discussing the corresponding engineering simulation programs.Finally,the difficulties of implementing advanced control technologies are addressed,and the future development of helicopter engineering simulators are highlighted.展开更多
This paper proposes a compensation method for using the Harmonic Amplitude-Phase Adaptive Control(HAPAC)to increase the precision of sinusoidal motion simulators. It also expounds on the HAPAC principle and structural...This paper proposes a compensation method for using the Harmonic Amplitude-Phase Adaptive Control(HAPAC)to increase the precision of sinusoidal motion simulators. It also expounds on the HAPAC principle and structural disposition, develops the HAPAC control laws and analyzes the system stability in the HAPAC. A method for further improving the precision using online identification of the system’s frequency-response models is presented. The tested data and tracking errors of the simulator demonstrate that the HAPAC makes the sinusoidal motions achieve higher precision than the common classical controls. The HAPAC can also be used in other tracking systems of precision sinusoidal motions.展开更多
In china,many students are unable to do experiments in computer architecture courses,which is very important in helping them to understand many key points.The reason is that the cost of the hardware required is too mu...In china,many students are unable to do experiments in computer architecture courses,which is very important in helping them to understand many key points.The reason is that the cost of the hardware required is too much.Besides,it is very difficult to do research study in hardware experiments.In our course,we adopted an alternative way to deal with the problem: to use software simulators,and designed a set of virtual experiments based on these simulators,which are described in detail in this paper.展开更多
Driving simulators involve the capability of simulating critical and dangerous driving situations up to the limits of active safety. They are employed for investigating the interactions of the driver-vehicle system un...Driving simulators involve the capability of simulating critical and dangerous driving situations up to the limits of active safety. They are employed for investigating the interactions of the driver-vehicle system under reproducible and non-dangerous conditions. Because of their flexibility they are well established in scientific research. They are mainly used in current automotive fields of research like driver assistance and autonomous driving systems. The development of assistance systems makes the human being as the directly concerned component irreplaceable in the development process. Here the use of driving simulators has become an essential element, because they offer the possibility to integrate the human being as a real part into the simulation environment. It must be considered that the circuit of information has to be the same as under real driving conditions. Otherwise the results are not transferable. This paper deals with the possibilities of presenting all information to the driver, which are necessary to give him a realistic impression of driving. A main subject is the sensation of yaw-movements, which could be of interest when novel kinds of moving base systems are designed.展开更多
Two applications of the hybrid simulators have been presented as examples: nonpulsatile VAD interaction with lumped parameters cardiovascular system numerical model and respirator interacting with the Dubois numerical...Two applications of the hybrid simulators have been presented as examples: nonpulsatile VAD interaction with lumped parameters cardiovascular system numerical model and respirator interacting with the Dubois numerical model of obstructive lung diseases. The results of simulations showed how the tested assist devices change biological system - assist device characteristics in the course of heart or lungs diseases and how it influences pressure and flow in a particular point of cardiovascular or respiratory system numerical model.展开更多
Oral processing is the first step in food digestion,thereby affecting the later steps of gastric and intestinaldigestion.In vitro digestion systems have been developed that can recreate certain conditions of gastric a...Oral processing is the first step in food digestion,thereby affecting the later steps of gastric and intestinaldigestion.In vitro digestion systems have been developed that can recreate certain conditions of gastric andintestinal digestion.However,obtaining physiologically accurate results of bioaccessibility or gastric emptyingrequires starting with a bolus that contains a realistic particle size distribution.Oral processing simulators havebeen developed that can produce realistic boluses,but they have not yet become part of the majority of in vitrogastrointestinal digestion workflows.In this mini review,we highlight recent literature showing how oral processingaffects the particle size distribution of food in the swallowed bolus and then call attention to resultsshowing how the size distribution of food particles affects variables such as gastric emptying and bioaccessibilityfrom both in vitro and in vivo research.Overall,results of these previous studies have established that oralprocessing has profound implications for physiological response during later stages of digestion.In view of this,we propose that oral processing simulators should be developed specifically for the purpose of integration with invitro digestion systems.Furthermore,we identify challenges and design criteria to guide the development of oralprocessing simulators that could improve the accuracy of results from in vitro digestion experiments whilepreserving the advantages of in vitro research.展开更多
The fidelity of financial market simulation is restricted by the so-called“non-identifiability”difficulty when calibrating high-frequency data.This paper first analyzes the inherent loss of data information in this ...The fidelity of financial market simulation is restricted by the so-called“non-identifiability”difficulty when calibrating high-frequency data.This paper first analyzes the inherent loss of data information in this difficulty,and proposes to use the Kolmogorov-Smirnov test(K-S)as the objective function for high-frequency calibration.Empirical studies verify that K-S has better identifiability of calibrating high-frequency data,while also leads to a much harder multi-modal landscape in the calibration space.To this end,we propose the adaptive stochastic ranking based negatively correlated search algorithm for improving the balance between exploration and exploitation.Experimental results on both simulated data and real market data demonstrate that the proposed method can obtain up to 36.0%improvement in high-frequency data calibration problems over the compared methods.展开更多
The uplift resistance of the soil overlying shield tunnels significantly impacts their anti-floating stability.However,research on uplift resistance concerning special-shaped shield tunnels is limited.This study combi...The uplift resistance of the soil overlying shield tunnels significantly impacts their anti-floating stability.However,research on uplift resistance concerning special-shaped shield tunnels is limited.This study combines numerical simulation with machine learning techniques to explore this issue.It presents a summary of special-shaped tunnel geometries and introduces a shape coefficient.Through the finite element software,Plaxis3D,the study simulates six key parameters—shape coefficient,burial depth ratio,tunnel’s longest horizontal length,internal friction angle,cohesion,and soil submerged bulk density—that impact uplift resistance across different conditions.Employing XGBoost and ANN methods,the feature importance of each parameter was analyzed based on the numerical simulation results.The findings demonstrate that a tunnel shape more closely resembling a circle leads to reduced uplift resistance in the overlying soil,whereas other parameters exhibit the contrary effects.Furthermore,the study reveals a diminishing trend in the feature importance of buried depth ratio,internal friction angle,tunnel longest horizontal length,cohesion,soil submerged bulk density,and shape coefficient in influencing uplift resistance.展开更多
UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechani...UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechanical properties are unclear.Molecular dynamics simulations are valuable but often limited by computational constraints.Our aim is to simulate higher molecular weights to better represent real UHMWPE fibers.We used Packmol and Polyply methodologies to construct PE systems,with Polyply reproducing more reasonable properties of UHMWPE fibers.Additionally,tensile simulations showed that orientation and crystallinity greatly impact Young's modulus more than molecular weight.Energy decomposition indicated that higher molecular weights lead to covalent bonds that can withstand more energy during stretching,thus increasing breaking strength.Combining simulations with machine learning,we found that orientation has the most significant impact on Young's modulus,contributing 60%,and molecular weight plays the most crucial role in determining the breaking strength,accounting for 65%.This study provides a theoretical basis and guidelines for enhancing UHMWPE's modulus and strength.展开更多
基金2024 Undergraduate Teaching Reform Research Project,Department of Education of Shandong Province,2025 Key Project of University-Level Education and Teaching Reform and Research,Research Title:Research on Talent Demand in the Biomedical Industry Chain and Strategies for High-Quality Higher Education Talent Cultivation in Shandong Province under the Background of New Quality Productivity(Project No.:Z2024208)Shandong Second Medical University,Research Title:Construction and Application of an Integrated Teaching Platform Combining Virtual Simulation and High-Fidelity Simulators in Obstetrics and Gynecology Practice Teaching,Project No.:2025SJZX053)。
文摘Objective:To analyze the effectiveness of an integrated teaching platform combining virtual reality(VR)technology and high-end simulators in practical obstetrics and gynecology teaching.Methods:A total of 39 interns who underwent obstetrics and gynecology internships from March 2023 to March 2024 were included in the reference group and received conventional practical teaching methods.Another 39 interns who underwent internships from April 2024 to April 2025 were included in the observation group and received the integrated teaching platform combining VR and high-end simulators.The teaching effects of the two groups were compared.Results:The observation group achieved higher assessment scores than the reference group,with higher scores in self-directed learning ability and clinical thinking ability after teaching,as well as higher teaching satisfaction(p<0.05).Conclusion:The integrated teaching platform combining VR and high-end simulators can improve the assessment scores of obstetrics and gynecology interns,cultivate their self-directed learning ability and clinical thinking ability,and achieve high teaching satisfaction.
文摘The use of simulators as educational tools for medical procedures is spreading rapidly and many efforts have been made for their implementation in gastrointestinal endoscopy training. Endoscopy simulation training has been suggested for ascertaining patient safety while positively influencing the trainees' learning curve. Virtual simulators are the most promising tool among all available types of simulators. These integrated modalities offer a human-like endoscopy experience by combining virtual images of the gastrointestinal tract and haptic realism with using a customized endoscope. From their first steps in the 1980s until today, research involving virtual endoscopic simulators can be divided in two categories: investigation of the impact of virtual simulator training in acquiring endoscopy skills and measuring competence. Emphasis should also be given to the financial impact of their implementation in endoscopy, including the cost of these state-of-theart simulators and the potential economic benefits from their usage. Advances in technology will contribute to the upgrade of existing models and the development of new ones; while further research should be carried out to discover new fields of application.
文摘The International Maritime Organization (IMO) has encouraged its member countries to introduce Formal Safety Assessment (FSA) for ship operations since the end of the last century. FSA can be used through certain formal assessing steps to generate effective recommendations and cautions to control marine risks and improve the safety of ships. On the basis of the brief introduction of FSA, this paper describes the ideas of applying FSA to the prevention of human error in ship operations. It especially discusses the investigation and analysis of the information and data using navigation simulators and puts forward some suggestions for the introduction and development of the FSA research work for safer ship operations.
文摘Objective: To explore the effectiveness of applying patient simulators combined with Internet Plus scenario simulation teaching models on intravenous (IV) infusion nursing education, and to provide scientific evidence for the implementation of advanced teaching models in future nursing education. Methods: Enrolled 60 nurses who took the IV infusion therapy training program in our hospital from January 2022 to December 2023 for research. 30 nurses who were trained in traditional teaching models from January to December 2022 were selected as the control group, and 30 nurses who were trained with simulation-based teaching models with methods including simulated patients, internet, online meetings which can be replayed and scenario simulation, etc. from January to December 2023 were selected as the experimental group. Evaluated the learning outcomes based on the Competency Inventory for Nursing Students (CINS), Problem-Solving Inventory (PSI), comprehensive learning ability, scientific research ability, and proficiency in the theoretical knowledge and practical skills of IV infusion therapy. Nursing quality, the incidence of IV infusion therapy complications and nurse satisfaction with different teaching models were also measured. Results: The scientific research ability, PSI scores, CINS scores, and comprehensive learning ability of the experimental group were better than those of the control group (P 0.05), and their assessment results of practical skills, nursing quality of IV infusion therapy during training, and satisfaction with teaching models were all better than those of the control group with statistical significance (P < 0.05). The incidence of IV infusion therapy complications in the experimental group was lower than that in the control group, indicating statistical significance (P < 0.05). Conclusions: Teaching models based on patient simulators combined with Internet Plus scenario simulation enable nursing students to learn more directly and practice at any time and in any place, and can improve their proficiency in IV infusion theoretical knowledge and skills (e.g. PICC catheterization), core competencies, problem-solving ability, comprehensive learning ability, scientific research ability and the ability to deal with complicated cases. Also, it helps provide high-quality nursing education, improve the nursing quality of IV therapy, reduce the incidence of related complications, and ensure the safety of patients with IV therapy.
文摘The advantages of a flat-panel X-ray source(FPXS)make it a promising candidate for imaging applications.Accurate imaging-system modeling and projection simulation are critical for analyzing imaging performance and resolving overlapping projection issues in FPXS.The conventional analytical ray-tracing approach is limited by the number of patterns and is not applicable to FPXS-projection calculations.However,the computation time of Monte Carlo(MC)simulation is independent of the size of the patterned arrays in FPXS.This study proposes two high-efficiency MC projection simulators for FPXS:a graphics processing unit(GPU)-based phase-space sampling MC(gPSMC)simulator and GPU-based fluence sampling MC(gFSMC)simulator.The two simulators comprise three components:imaging-system modeling,photon initialization,and physical-interaction simulations in the phantom.Imaging-system modeling was performed by modeling the FPXS,imaging geometry,and detector.The gPSMC simulator samples the initial photons from the phase space,whereas the gFSMC simulator performs photon initialization from the calculated energy spectrum and fluence map.The entire process of photon interaction with the geometry and arrival at the detector was simulated in parallel using multiple GPU kernels,and projections based on the two simulators were calculated.The accuracies of the two simulators were evaluated by comparing them with the conventional analytical ray-tracing approach and acquired projections,and the efficiencies were evaluated by comparing the computation time.The results of simulated and realistic experiments illustrate the accuracy and efficiency of the proposed gPSMC and gFSMC simulators in the projection calculation of various phantoms.
基金the projects 75926 with the Colombian Navythe project 2020021 between Universidad de los Andes and the Military Hospital in Colombia.
文摘Background This paper shows how current collaborative virtual environments(VEs)such as Mozilla Hubs and AltspaceVR can aid in the task of requirements gathering in VR for simulation and training.Methods We performed a qualitative study on our use of these technologies in the requirements gathering of two projects.Results Our results show that requirements gathering in virtual reality has an impact on the process of requirements identification.We report advantages and shortcomings that will be of interest to future practitioners.For example,we found that VR sessions for requirements gathering in current VEs could benefit from better pointers and better sound quality.Conclusion Current VEs are useful for the requirements gathering task in the development of VR simulators and VR training environments.
文摘This article describes numerical simulation of gas pipeline network operation using high-accuracy computational fluid dynamics (CFD) simulators of the modes of gas mixture transmission through long, multi-line pipeline systems (CFD-simulator). The approach used in CFD-simulators for modeling gas mixture transmission through long, branched, multi-section pipelines is based on tailoring the full system of fluid dynamics equations to conditions of unsteady, non-isothermal processes of the gas mixture flow. Identification, in a CFD-simulator, of safe parameters for gas transmission through compressor stations amounts to finding the interior points of admissible sets described by systems of nonlinear algebraic equalities and inequalities. Such systems of equalities and inequalities comprise a formal statement of technological, design, operational and other constraints to which operation of the network equipment is subject. To illustrate the practicability of the method of numerical simulation of a gas transmission network, we compare computation results and gas flow parameters measured on-site at the gas transmission enter-prise.
基金supported in part by the project from the ZTEthe National Natural Science Foundation of China under Grant 61622101 and Grant 61571020National Science and Technology Major Project under Grant 2018ZX03001031
文摘In this paper, we consider a novel two-dimensional(2D) geometry-based stochastic model(GBSM) for multiple-input multiple-output(MIMO) vehicle-to-vehicle(V2V) wideband fading channels. The proposed model employs the combination of a two-ring model and a multiple confocal ellipses model, where the signal is sum of the line-of-sight(Lo S) component, single-bounced(SB) rays, and double-bounced(DB) rays. Based on the reference model, we derive some expressions of channel statistical properties, including space-time correlation function(STCF), Doppler spectral power density(DPSD), envelope level crossing rate(LCR) and average fade duration(AFD). In addition, corresponding deterministic and stochastic simulation models are developed based on the reference model. Moreover, we compare the statistical properties of the reference model and the two simulation models in different scenarios and investigate the impact of different vehicular traffic densities(VTDs) on the channel statistical properties of the proposed model. Finally, the great agreement between simulation models and the reference model demonstrates not only the utility of simulation models, but also the correctness of theoretical derivations and simulations.
基金funded partially by the Australian Government through the Australian Research Council’s Linkage Infrastructure,Equipment and Facilities (LIEF)funding scheme (LE130100133)。
文摘A critical challenge of any blast simulation facility is in producing the widest possible pressure-impulse range for matching against equivalent high-explosive events.Shock tubes and blast simulators are often constrained with the lack of effective ways to control blast wave profiles and as a result have a limited performance range.Some wave shaping techniques employed in some facilities are reviewed but often necessitate extensive geometric modifications,inadvertently cause flow anomalies,and/or are only applicable under very specific configurations.This paper investigates controlled venting as an expedient way for waveforms to be tuned without requiring extensive modifications to the driver or existing geometry and could be widely applied by existing and future blast simulation and shock tube facilities.The use of controlled venting is demonstrated experimentally using the Advanced Blast Simulator(shock tube)at the Australian National Facility of Physical Blast Simulation and via numerical flow simulations with Computational Fluid Dynamics.Controlled venting is determined as an effective method for mitigating the impact of re-reflected waves within the blast simulator.This control method also allows for the adjustment of parameters such as tuning the peak overpressure,the positive phase duration,and modifying the magnitude of the negative phase and the secondary shock of the blast waves.This paper is concluded with an illustration of the potential expanded performance range of the Australian blast simulation facility when controlled venting for blast waveform tailoring as presented in this paper is applied.
基金supported by the Fundamental Research Funds for the Central Universities (No. XBC16010)
文摘A practical survey on engineering implementation of flight control laws on helicopter engineering simulators is proposed.Advances of helicopter engineering simulators are introduced.Practical flight control technologies are reviewed,with an emphasis on discussing the corresponding engineering simulation programs.Finally,the difficulties of implementing advanced control technologies are addressed,and the future development of helicopter engineering simulators are highlighted.
文摘This paper proposes a compensation method for using the Harmonic Amplitude-Phase Adaptive Control(HAPAC)to increase the precision of sinusoidal motion simulators. It also expounds on the HAPAC principle and structural disposition, develops the HAPAC control laws and analyzes the system stability in the HAPAC. A method for further improving the precision using online identification of the system’s frequency-response models is presented. The tested data and tracking errors of the simulator demonstrate that the HAPAC makes the sinusoidal motions achieve higher precision than the common classical controls. The HAPAC can also be used in other tracking systems of precision sinusoidal motions.
文摘In china,many students are unable to do experiments in computer architecture courses,which is very important in helping them to understand many key points.The reason is that the cost of the hardware required is too much.Besides,it is very difficult to do research study in hardware experiments.In our course,we adopted an alternative way to deal with the problem: to use software simulators,and designed a set of virtual experiments based on these simulators,which are described in detail in this paper.
文摘Driving simulators involve the capability of simulating critical and dangerous driving situations up to the limits of active safety. They are employed for investigating the interactions of the driver-vehicle system under reproducible and non-dangerous conditions. Because of their flexibility they are well established in scientific research. They are mainly used in current automotive fields of research like driver assistance and autonomous driving systems. The development of assistance systems makes the human being as the directly concerned component irreplaceable in the development process. Here the use of driving simulators has become an essential element, because they offer the possibility to integrate the human being as a real part into the simulation environment. It must be considered that the circuit of information has to be the same as under real driving conditions. Otherwise the results are not transferable. This paper deals with the possibilities of presenting all information to the driver, which are necessary to give him a realistic impression of driving. A main subject is the sensation of yaw-movements, which could be of interest when novel kinds of moving base systems are designed.
文摘Two applications of the hybrid simulators have been presented as examples: nonpulsatile VAD interaction with lumped parameters cardiovascular system numerical model and respirator interacting with the Dubois numerical model of obstructive lung diseases. The results of simulations showed how the tested assist devices change biological system - assist device characteristics in the course of heart or lungs diseases and how it influences pressure and flow in a particular point of cardiovascular or respiratory system numerical model.
基金supported,in part,by the Oregon Agricultural Experi-ment Station with funding from the Hatch Act capacity funding pro-gram,award number NI25HFPXXXXXG022,from the USDA National Institute of Food and Agriculture。
文摘Oral processing is the first step in food digestion,thereby affecting the later steps of gastric and intestinaldigestion.In vitro digestion systems have been developed that can recreate certain conditions of gastric andintestinal digestion.However,obtaining physiologically accurate results of bioaccessibility or gastric emptyingrequires starting with a bolus that contains a realistic particle size distribution.Oral processing simulators havebeen developed that can produce realistic boluses,but they have not yet become part of the majority of in vitrogastrointestinal digestion workflows.In this mini review,we highlight recent literature showing how oral processingaffects the particle size distribution of food in the swallowed bolus and then call attention to resultsshowing how the size distribution of food particles affects variables such as gastric emptying and bioaccessibilityfrom both in vitro and in vivo research.Overall,results of these previous studies have established that oralprocessing has profound implications for physiological response during later stages of digestion.In view of this,we propose that oral processing simulators should be developed specifically for the purpose of integration with invitro digestion systems.Furthermore,we identify challenges and design criteria to guide the development of oralprocessing simulators that could improve the accuracy of results from in vitro digestion experiments whilepreserving the advantages of in vitro research.
基金supported by the National Natural Science Foundation of China(Nos.62272210,62250710682,and 62331014).
文摘The fidelity of financial market simulation is restricted by the so-called“non-identifiability”difficulty when calibrating high-frequency data.This paper first analyzes the inherent loss of data information in this difficulty,and proposes to use the Kolmogorov-Smirnov test(K-S)as the objective function for high-frequency calibration.Empirical studies verify that K-S has better identifiability of calibrating high-frequency data,while also leads to a much harder multi-modal landscape in the calibration space.To this end,we propose the adaptive stochastic ranking based negatively correlated search algorithm for improving the balance between exploration and exploitation.Experimental results on both simulated data and real market data demonstrate that the proposed method can obtain up to 36.0%improvement in high-frequency data calibration problems over the compared methods.
基金Guangzhou Metro Scientific Research Project(No.JT204-100111-23001)Chongqing Municipal Special Project for Technological Innovation and Application Development(No.CSTB2022TIAD-KPX0101)Science and Technology Research and Development Program of China State Railway Group Co.,Ltd.(No.N2023G045)。
文摘The uplift resistance of the soil overlying shield tunnels significantly impacts their anti-floating stability.However,research on uplift resistance concerning special-shaped shield tunnels is limited.This study combines numerical simulation with machine learning techniques to explore this issue.It presents a summary of special-shaped tunnel geometries and introduces a shape coefficient.Through the finite element software,Plaxis3D,the study simulates six key parameters—shape coefficient,burial depth ratio,tunnel’s longest horizontal length,internal friction angle,cohesion,and soil submerged bulk density—that impact uplift resistance across different conditions.Employing XGBoost and ANN methods,the feature importance of each parameter was analyzed based on the numerical simulation results.The findings demonstrate that a tunnel shape more closely resembling a circle leads to reduced uplift resistance in the overlying soil,whereas other parameters exhibit the contrary effects.Furthermore,the study reveals a diminishing trend in the feature importance of buried depth ratio,internal friction angle,tunnel longest horizontal length,cohesion,soil submerged bulk density,and shape coefficient in influencing uplift resistance.
基金financially supported by the National Natural Science Foundation of China(Nos.52303298 and 52233002)。
文摘UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechanical properties are unclear.Molecular dynamics simulations are valuable but often limited by computational constraints.Our aim is to simulate higher molecular weights to better represent real UHMWPE fibers.We used Packmol and Polyply methodologies to construct PE systems,with Polyply reproducing more reasonable properties of UHMWPE fibers.Additionally,tensile simulations showed that orientation and crystallinity greatly impact Young's modulus more than molecular weight.Energy decomposition indicated that higher molecular weights lead to covalent bonds that can withstand more energy during stretching,thus increasing breaking strength.Combining simulations with machine learning,we found that orientation has the most significant impact on Young's modulus,contributing 60%,and molecular weight plays the most crucial role in determining the breaking strength,accounting for 65%.This study provides a theoretical basis and guidelines for enhancing UHMWPE's modulus and strength.
