The evolution of misfit dislocation network at γ/γ＇ phase interfaces and the stress distribution characteristics of Ni-based single-crystal superalloys under different temperatures of 0, 100 and 300 K are studied b...The evolution of misfit dislocation network at γ/γ＇ phase interfaces and the stress distribution characteristics of Ni-based single-crystal superalloys under different temperatures of 0, 100 and 300 K are studied by molecular dynamics （MD） simulation. It was found that a closed three-dimensional misfit dislocation network appears on the γ/γ＇ phase interfaces, and the shape of the dislocation network is independent of the lattice mismatch. Under the influence of the temperature, the dislocation network gradually becomes irregular, a/2 [110] dislocations in the γ matrix phase emit and partly cut into the γ＇ phase with the increase in temperature. The dislocation evolution is related to the local stress field, a peak stress occurs at γ/γ＇ phase interface, and with the increase in temperature and relaxation times, the stress in the γ phase gradually increases, the number of dislocations in the γ phase increases and cuts into γ＇ phase from the interfaces where dislocation network is damaged. The results provide important information for understanding the temperature dependence of the dislocation evolution and mechanical properties of Ni-based single-crystal superalloys.展开更多
Ongoing research is described that is focused upon modelling the space base information network and simulating its behaviours： simulation of spaced based communications and networking project. Its objective is to dem...Ongoing research is described that is focused upon modelling the space base information network and simulating its behaviours： simulation of spaced based communications and networking project. Its objective is to demonstrate the feasibility of producing a tool that can provide a performance evaluation of various eonstellation access techniques and routing policies. The architecture and design of the simulation system are explored. The algorithm of data routing and instrument scheduling in this project is described. Besides these, the key methodologies of simulating the inter-satellite link features in the data transmissions are also discussed. The performance of both instrument scheduling algorithm and routing schemes is evaluated and analyzed through extensive simulations under a typical scenario.展开更多
<div style="text-align:justify;"> <strong>Background and Aim:</strong><span "=""> The only way to survive a sudden cardiac arrest is when the CPR is performed immediate...<div style="text-align:justify;"> <strong>Background and Aim:</strong><span "=""> The only way to survive a sudden cardiac arrest is when the CPR is performed immediately after the arrest. The focus of the present research study is to assess the effectiveness of a pre</span>- and post-simulation-based BLS training (BLS) and the outcome was<span "=""> measured on the basis of patient survival after the cardiac arrest. <b>Study Design</b><strong>:</strong> This pre- and post-training BLS/CPR training study enrolled all nursing staff, all hospital residents, internees, throughout the hospital in a simulation-based BLS training as per the standards of American Heart Association (AHA), to make them respond to immediate resuscitation and code blue activation during the cardiac arrest within the hospital premises including ED, wards, ICUs, MRI, CT and all miscellaneous areas. The providers completed self-efficacy questionnaires as per the AHA protocol before being certified and were evaluated during the emergency in hospital cardiopulmonary arrest. <b>Results: </b>296 nursing staff, 206 non-healthcare professionals, 143 residents, 212 internees, and 98 medical staff grade doctors completed the BLS training (total 955 hospital staff—providers) were graded for the response by pre- and post-training testing. In the course of pre</span>-BLS training period out of the 250 cardiac arrest patients, 68 patients (27.2%) had ROSC, while after instituting the BLS training period, 143 individuals (40.86%) of the 350 patients who had cardiac arrest had ROSC (p<span "=""> </span><<span "=""> </span>0.05<span "="">). <b>Conclusion: </b>A simulation-based CPR and BLS training curriculum greatly improves patient outcome by reducing mortality and morbidity with improved subjectivity, self-efficiency along with the objective assessment of the performance scores during acute cardiac arrest in Emergency Cardiovascular Care (ECC).</span> </div>展开更多
Helicopters are playing an increasingly important part in emergency relief, such as earthquake rescue, firefighting and medical transport. With the development of virtual simulation technology, virtual simulation-base...Helicopters are playing an increasingly important part in emergency relief, such as earthquake rescue, firefighting and medical transport. With the development of virtual simulation technology, virtual simulation-based training is widely used in the training of the helicopter crew especially for the dangerous and costly missions mentioned above. A complete training effectiveness evaluation method is proposed to evaluate the trainees＇ training effect based on virtual simulation in this paper. A key to this method is regarding the complicated process as a discrete event-activity flow system and establishing the evaluation indicator system. Then expert group and Analytical Network Process（ANP） are applied to determine the weight of indicators. When the training data are processed, there is a novel attempt to apply Fuzzy Comprehensive Evaluation（FCE） model to calculate the two categories of indicators. Eventually, an experiment and the analysis were carried out to validate the evaluation method.展开更多
In this paper, a distributed muting strategy based on simplified topology （DRBST） was proposed for LEO satellite networks. The topology of LEO satellite networks was simplified aiming at minimizing intersatellite li...In this paper, a distributed muting strategy based on simplified topology （DRBST） was proposed for LEO satellite networks. The topology of LEO satellite networks was simplified aiming at minimizing intersatellite links handover number. To optimize the route based on the simplified topology, we considered not only the transmission delay but also the queuing delay and the processing delay, which were analyzed using Markov chain and determined using a novel methodology. The DRBST algorithm was simulated in a LEO satellite networks model built using OPNET. The simulation results demonstrate that the low complexity DRBST algorithm can guarantee end-to-end delay bound. Moreover, the muting protocol cost is much less than traditional algorithms.展开更多
Network-based manufacturing is a kind of distributed system, which enables manufacturers to finish production tasks as well as to grasp the opportunities in the market, even if manufacturing resources are insufficient...Network-based manufacturing is a kind of distributed system, which enables manufacturers to finish production tasks as well as to grasp the opportunities in the market, even if manufacturing resources are insufficient. One of the main problems in network-based manufacturing is the allocation of resources and the assignment of tasks rationally, according to flexible resource distribution. The mapping rules and relations between production techniques and resources are proposed, followed by the definition of the resource unit. Ultimately, the genetic programming method for the optimization of the manufacturing system is put forward. A set of software for the optimization system of simulation process using genetic programming techniques has been developed, and the problems of manufacturing resource planning in network-based manufacturing are solved with the simulation of optimizing methods by genetic programming. The optimum proposal of hardware planning, selection of company and scheduling will be obtained in theory to help company managers in scientific decision-making.展开更多
As the speed of optical access networks soars with ever increasing multiple services, the service-supporting ability of optical access networks suffers greatly from the shortage of service awareness. Aiming to solve t...As the speed of optical access networks soars with ever increasing multiple services, the service-supporting ability of optical access networks suffers greatly from the shortage of service awareness. Aiming to solve this problem, a hierarchy Bayesian model based services awareness mechanism is proposed for high-speed optical access networks. This approach builds a so-called hierarchy Bayesian model, according to the structure of typical optical access networks. Moreover, the proposed scheme is able to conduct simple services awareness operation in each optical network unit(ONU) and to perform complex services awareness from the whole view of system in optical line terminal(OLT). Simulation results show that the proposed scheme is able to achieve better quality of services(Qo S), in terms of packet loss rate and time delay.展开更多
The simulator is a combination of computational functions describing physical system, distributed rule and knowledge bases, and a reasoning machine, all executing in parallel. The hardware,comprising two levels of mul...The simulator is a combination of computational functions describing physical system, distributed rule and knowledge bases, and a reasoning machine, all executing in parallel. The hardware,comprising two levels of multiprocessor network-- a T800 transputer and STD--BUS computer systems--and analogue and I/O boards, has been used successfully to train and simulate a 100 MW power system at a low cost. The system has wide applications in industry.展开更多
Based on the gene-protein-reaction (GPR) model of S. cerevisiae_iND750 and the method of constraint-based analysis, we first calculated the metabolic flux distribution of S. cere-visiae_iND750. Then we calculated the ...Based on the gene-protein-reaction (GPR) model of S. cerevisiae_iND750 and the method of constraint-based analysis, we first calculated the metabolic flux distribution of S. cere-visiae_iND750. Then we calculated the deletion impact of 438 calculable genes, one by one, on the metabolic flux redistribution of S. cere-visiae_iND750. Next we analyzed the correlation between v (describing deletion impact of one gene) and d (connection degree of one gene) and the correlation between v and Vgene (flux sum controlled by one gene), and found that both of them were not of linear relation. Furthermore, we sought out 38 important genes that most greatly affected the metabolic flux distribution, and determined their functional subsystems. We also found that many of these key genes were related to many but not several subsystems. Because the in silico model of S. cere-visiae_iND750 has been tested by many ex-periments, thus is credible, we can conclude that the result we obtained has biological sig-nificance.展开更多
Train traffic rescheduling is a complicated and large-scaled combinatorial problem. According to the characteristics of China railway system and from the point of practical use, this paper introduces a rule-based trai...Train traffic rescheduling is a complicated and large-scaled combinatorial problem. According to the characteristics of China railway system and from the point of practical use, this paper introduces a rule-based train traffic reschedule interactive simulator. It can be used as a powerful training tool to train the dispatcher and to carry out experimental analysis. The production rules are used as the basic for describing the processes to be simulated. With the increase of rule, users can easily upgrade the simulator by adding their own rules.展开更多
Objective:Proficiency in endoscopic endonasal skull base surgery requires both substantial baseline training and progressive lifelong learning.Endoscopic simulation models continue to evolve in an effort to optimize t...Objective:Proficiency in endoscopic endonasal skull base surgery requires both substantial baseline training and progressive lifelong learning.Endoscopic simulation models continue to evolve in an effort to optimize trainee education and preoperative preparation and improve surgical outcomes.The current scoping review systematically reviews all available literature and synthesizes the current paradigms of simulation models for endoscopic skull base surgery training and skill enhancement.Methods:In accordance with Preferred Reporting Items for Systemic Review and Meta-Analyses guidelines,we systematically searched PubMed,Embase,CINAHL,and Cochrane databases.Studies were categorized according to the type of simulation models investigated.Results:We identified 238 unique references,with 55 studies ultimately meeting inclusion criteria.Of these,19 studies described cadaveric dissection models,17 discussed three-dimensional(3D)printed models,14 examined virtual surgical planning and augmented reality-based models,and five 5 articles described task trainers.Conclusions:There are a wide variety of simulation models for endoscopic skull base surgery,including high-fidelity cadaveric,virtual reality,and 3D-printed models.These models are an asset for trainee development and preoperative surgical preparation.展开更多
To simulate the rumor propagation process on online social network during emergency, a new rumor propagation model was built based on active immune mechanism. The rumor propagation mechanisms were analyzed and corresp...To simulate the rumor propagation process on online social network during emergency, a new rumor propagation model was built based on active immune mechanism. The rumor propagation mechanisms were analyzed and corresponding parameters were defined. BA scale free network and NW small world network that can be used for representing the online social network structure were constructed and their characteristics were compared. Agent-based simulations were conducted on both networks and results show that BA scale free network is more conductive to spreading rumors and it can facilitate the rumor refutation process at the same time. Rumors paid attention to by more people is likely to spread quicker and broader but for which the rumor refutation process will be more effective. The model provides a useful tool for understanding and predicting the rumor propagation process on online social network during emergency, providing useful instructions for rumor propagation intervention.展开更多
The use of virtual simulation-based training continues to expand, as organizations explore alternative methods to reduce the cost of training. While virtual simulation has been empirically validated to be effective in...The use of virtual simulation-based training continues to expand, as organizations explore alternative methods to reduce the cost of training. While virtual simulation has been empirically validated to be effective in the transfer of skills to the live environment, what is still unknown is what effect, if any, that an individual’s sense of presence in the simulation has on their performance. In this paper, we examine the relationship between presence and performance while performing a psychomotor task in a virtual environment. The independent variables were visual display and expertise level. The dependent variables were presence and performance. We found evidence of a moderate relationship between the degree of presence experienced in the simulation and an individual’s performance over three training trials. Results of this study may inspire future research to investigate whether higher presence in virtual simulation results in higher performance.展开更多
A simulation model was proposed to investigate the relationship between train delays and passenger delays and to predict the dynamic passenger distribution in a large-scale rail transit network. It was assumed that th...A simulation model was proposed to investigate the relationship between train delays and passenger delays and to predict the dynamic passenger distribution in a large-scale rail transit network. It was assumed that the time varying original-destination demand and passenger path choice probability were given. Passengers were assumed not to change their destinations and travel paths after delay occurs. CapaciW constraints of train and queue rules of alighting and boarding were taken into account. By using the time-driven simulation, the states of passengers, trains and other facilities in the network were updated every time step. The proposed methodology was also tested in a real network, for demonstration. The results reveal that short train delay does not necessarily result in passenger delays, while, on the contrary, some passengers may get benefits from the short delay. However, large initial train delay may result in not only knock-on train and passenger delays along the same line, but also the passenger delays across the entire rail transit network.展开更多
Although train modeling research is vast, most available simulation tools are confined to city-or trip-scale analysis, primarily offering micro-level simulations of network segments. This paper addresses this void by ...Although train modeling research is vast, most available simulation tools are confined to city-or trip-scale analysis, primarily offering micro-level simulations of network segments. This paper addresses this void by developing the Ne Train Sim simulator for heavy long-haul freight trains on a network of multiple intersecting tracks. The main objective of this simulator is to enable a comprehensive analysis of energy consumption and the associated carbon footprint for the entire train system. Four case studies were conducted to demonstrate the simulator's performance. The first case study validates the model by comparing Ne Train Sim output to empirical trajectory data. The results demonstrate that the simulated trajectory is precise enough to estimate the train energy consumption and carbon dioxide emissions. The second application demonstrates the train-following model considering six trains following each other. The results showcase the model ability to maintain safefollowing distances between successive trains. The next study highlights the simulator's ability to resolve train conflicts for different scenarios. Finally, the suitability of the Ne Train Sim for modeling realistic railroad networks is verified through the modeling of the entire US network and comparing alternative powertrains on the fleet energy consumption.展开更多
The on-board diagnosis network is the nervous system of high-speed Maglev trains, connecting all controller sensors, and corresponding devices to realize the information acquisition and control. In order to study the ...The on-board diagnosis network is the nervous system of high-speed Maglev trains, connecting all controller sensors, and corresponding devices to realize the information acquisition and control. In order to study the on-board diagnosis network＇s security and reliability, a simulation model for the on-board diagnosis network of high-speed Maglev trains with the optimal network engineering tool （OPNET） was built to analyze the network＇s performance, such as response error and bit error rate on the network load, throughput, and node-state response. The simulation model was verified with an actual on-board diagnosis network structure. The results show that the model results obtained are in good agreement with actual system performance and can be used to achieve actual communication network optimization and control algorithms.展开更多
Simulating large-scale and complex systems is commonly considered a difficult and time-consuming task. In this paper, we propose a partial simulation way to speed up the simulation with real time demands. It is based ...Simulating large-scale and complex systems is commonly considered a difficult and time-consuming task. In this paper, we propose a partial simulation way to speed up the simulation with real time demands. It is based on the idea that a train traffic diagram is expressed in a network, and through calculating the maximal long path in the network the simulation is done, but only within a particular partial area.Upon this, we let it become a problem oriented simulation. The simulation could be started at any time,from any trains or at any stations and stopped as the same way according to the problem to be concerned.We can use this kind of simulation to analyse or confirm the correctness of traffic schedule at a high speed to meet the real time demands.展开更多
Based on the discrete time method, an effective movement control model is designed for a group of high- speed trains on a rail network. The purpose of the model is to investigate the specific traffic characteristics o...Based on the discrete time method, an effective movement control model is designed for a group of high- speed trains on a rail network. The purpose of the model is to investigate the specific traffic characteristics of high-speed trains under the interruption of stochastic irregular events. In the model, the high-speed rail traffic system is supposed to be equipped with the moving-block signalling system to guarantee maximum traversing capacity of the railway. To keep the safety of trains＇ movements, some operational strategies are proposed to control the movements of trains in the model, including traction operation, braking operation, and entering-station operation. The numerical simulations show that the designed model can well describe the movements of high-speed trains on the rail network. The research results can provide the useful information not only for investigating the propagation features of relevant delays under the irregular disturbance but also for rerouting and reseheduling trains on the rail network.展开更多
Traditional algorithms do not fully utilize the timing information of non-cooperative targets,and setting too many motion parameters can lead to complex dynamic model calculations.This paper proposes a long short-term...Traditional algorithms do not fully utilize the timing information of non-cooperative targets,and setting too many motion parameters can lead to complex dynamic model calculations.This paper proposes a long short-term memory(LSTM)network-based method for estimating the parameters of the active segment of the non-cooperative target under single-satellite observation.Based on the simulation training set of the active segment of the non-cooperative target,the network parameters of the LSTM network are designed,the motion characteristics of the active segment of the non-cooperative target are fully excavated through data-driven methods,and the candidate cutting trajectories are screened and predicted to realize the estimation of the motion parameters of the active segment of the non-cooperative target under the condition of single-satellite observation.The experimental results show that the estimation method proposed in this paper can effectively deal with the inaccurate problem with the non-cooperative target’s active segment motion model established under the condition of single-satellite observation,obtain more accurate active segment motion parameters,and provide a feasible new idea and method for the parameter estimation of the active segment of the non-cooperative target under the single-satellite observation.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.11102139 and 11472195)the Natural Science Foundation of Hubei Province of China(No.2014CFB713)
文摘The evolution of misfit dislocation network at γ/γ＇ phase interfaces and the stress distribution characteristics of Ni-based single-crystal superalloys under different temperatures of 0, 100 and 300 K are studied by molecular dynamics （MD） simulation. It was found that a closed three-dimensional misfit dislocation network appears on the γ/γ＇ phase interfaces, and the shape of the dislocation network is independent of the lattice mismatch. Under the influence of the temperature, the dislocation network gradually becomes irregular, a/2 [110] dislocations in the γ matrix phase emit and partly cut into the γ＇ phase with the increase in temperature. The dislocation evolution is related to the local stress field, a peak stress occurs at γ/γ＇ phase interface, and with the increase in temperature and relaxation times, the stress in the γ phase gradually increases, the number of dislocations in the γ phase increases and cuts into γ＇ phase from the interfaces where dislocation network is damaged. The results provide important information for understanding the temperature dependence of the dislocation evolution and mechanical properties of Ni-based single-crystal superalloys.
基金This project was supported by the National "863" High-Tech Research and Development Program of China(2002AA7170)
文摘Ongoing research is described that is focused upon modelling the space base information network and simulating its behaviours： simulation of spaced based communications and networking project. Its objective is to demonstrate the feasibility of producing a tool that can provide a performance evaluation of various eonstellation access techniques and routing policies. The architecture and design of the simulation system are explored. The algorithm of data routing and instrument scheduling in this project is described. Besides these, the key methodologies of simulating the inter-satellite link features in the data transmissions are also discussed. The performance of both instrument scheduling algorithm and routing schemes is evaluated and analyzed through extensive simulations under a typical scenario.
文摘<div style="text-align:justify;"> <strong>Background and Aim:</strong><span "=""> The only way to survive a sudden cardiac arrest is when the CPR is performed immediately after the arrest. The focus of the present research study is to assess the effectiveness of a pre</span>- and post-simulation-based BLS training (BLS) and the outcome was<span "=""> measured on the basis of patient survival after the cardiac arrest. <b>Study Design</b><strong>:</strong> This pre- and post-training BLS/CPR training study enrolled all nursing staff, all hospital residents, internees, throughout the hospital in a simulation-based BLS training as per the standards of American Heart Association (AHA), to make them respond to immediate resuscitation and code blue activation during the cardiac arrest within the hospital premises including ED, wards, ICUs, MRI, CT and all miscellaneous areas. The providers completed self-efficacy questionnaires as per the AHA protocol before being certified and were evaluated during the emergency in hospital cardiopulmonary arrest. <b>Results: </b>296 nursing staff, 206 non-healthcare professionals, 143 residents, 212 internees, and 98 medical staff grade doctors completed the BLS training (total 955 hospital staff—providers) were graded for the response by pre- and post-training testing. In the course of pre</span>-BLS training period out of the 250 cardiac arrest patients, 68 patients (27.2%) had ROSC, while after instituting the BLS training period, 143 individuals (40.86%) of the 350 patients who had cardiac arrest had ROSC (p<span "=""> </span><<span "=""> </span>0.05<span "="">). <b>Conclusion: </b>A simulation-based CPR and BLS training curriculum greatly improves patient outcome by reducing mortality and morbidity with improved subjectivity, self-efficiency along with the objective assessment of the performance scores during acute cardiac arrest in Emergency Cardiovascular Care (ECC).</span> </div>
文摘Helicopters are playing an increasingly important part in emergency relief, such as earthquake rescue, firefighting and medical transport. With the development of virtual simulation technology, virtual simulation-based training is widely used in the training of the helicopter crew especially for the dangerous and costly missions mentioned above. A complete training effectiveness evaluation method is proposed to evaluate the trainees＇ training effect based on virtual simulation in this paper. A key to this method is regarding the complicated process as a discrete event-activity flow system and establishing the evaluation indicator system. Then expert group and Analytical Network Process（ANP） are applied to determine the weight of indicators. When the training data are processed, there is a novel attempt to apply Fuzzy Comprehensive Evaluation（FCE） model to calculate the two categories of indicators. Eventually, an experiment and the analysis were carried out to validate the evaluation method.
基金Supported by the National Science Foundation of China （No. 60873219）.
文摘In this paper, a distributed muting strategy based on simplified topology （DRBST） was proposed for LEO satellite networks. The topology of LEO satellite networks was simplified aiming at minimizing intersatellite links handover number. To optimize the route based on the simplified topology, we considered not only the transmission delay but also the queuing delay and the processing delay, which were analyzed using Markov chain and determined using a novel methodology. The DRBST algorithm was simulated in a LEO satellite networks model built using OPNET. The simulation results demonstrate that the low complexity DRBST algorithm can guarantee end-to-end delay bound. Moreover, the muting protocol cost is much less than traditional algorithms.
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2002AA411030)National Defense Foundation Scientific Research of China (Grant No. d2520061124)
文摘Network-based manufacturing is a kind of distributed system, which enables manufacturers to finish production tasks as well as to grasp the opportunities in the market, even if manufacturing resources are insufficient. One of the main problems in network-based manufacturing is the allocation of resources and the assignment of tasks rationally, according to flexible resource distribution. The mapping rules and relations between production techniques and resources are proposed, followed by the definition of the resource unit. Ultimately, the genetic programming method for the optimization of the manufacturing system is put forward. A set of software for the optimization system of simulation process using genetic programming techniques has been developed, and the problems of manufacturing resource planning in network-based manufacturing are solved with the simulation of optimizing methods by genetic programming. The optimum proposal of hardware planning, selection of company and scheduling will be obtained in theory to help company managers in scientific decision-making.
基金supported by the Science and Technology Project of State Grid Corporation of China:"Research on the Power-Grid Services Oriented"IP+Optics"Coordination Choreography Technology"
文摘As the speed of optical access networks soars with ever increasing multiple services, the service-supporting ability of optical access networks suffers greatly from the shortage of service awareness. Aiming to solve this problem, a hierarchy Bayesian model based services awareness mechanism is proposed for high-speed optical access networks. This approach builds a so-called hierarchy Bayesian model, according to the structure of typical optical access networks. Moreover, the proposed scheme is able to conduct simple services awareness operation in each optical network unit(ONU) and to perform complex services awareness from the whole view of system in optical line terminal(OLT). Simulation results show that the proposed scheme is able to achieve better quality of services(Qo S), in terms of packet loss rate and time delay.
文摘The simulator is a combination of computational functions describing physical system, distributed rule and knowledge bases, and a reasoning machine, all executing in parallel. The hardware,comprising two levels of multiprocessor network-- a T800 transputer and STD--BUS computer systems--and analogue and I/O boards, has been used successfully to train and simulate a 100 MW power system at a low cost. The system has wide applications in industry.
文摘Based on the gene-protein-reaction (GPR) model of S. cerevisiae_iND750 and the method of constraint-based analysis, we first calculated the metabolic flux distribution of S. cere-visiae_iND750. Then we calculated the deletion impact of 438 calculable genes, one by one, on the metabolic flux redistribution of S. cere-visiae_iND750. Next we analyzed the correlation between v (describing deletion impact of one gene) and d (connection degree of one gene) and the correlation between v and Vgene (flux sum controlled by one gene), and found that both of them were not of linear relation. Furthermore, we sought out 38 important genes that most greatly affected the metabolic flux distribution, and determined their functional subsystems. We also found that many of these key genes were related to many but not several subsystems. Because the in silico model of S. cere-visiae_iND750 has been tested by many ex-periments, thus is credible, we can conclude that the result we obtained has biological sig-nificance.
文摘Train traffic rescheduling is a complicated and large-scaled combinatorial problem. According to the characteristics of China railway system and from the point of practical use, this paper introduces a rule-based train traffic reschedule interactive simulator. It can be used as a powerful training tool to train the dispatcher and to carry out experimental analysis. The production rules are used as the basic for describing the processes to be simulated. With the increase of rule, users can easily upgrade the simulator by adding their own rules.
文摘Objective:Proficiency in endoscopic endonasal skull base surgery requires both substantial baseline training and progressive lifelong learning.Endoscopic simulation models continue to evolve in an effort to optimize trainee education and preoperative preparation and improve surgical outcomes.The current scoping review systematically reviews all available literature and synthesizes the current paradigms of simulation models for endoscopic skull base surgery training and skill enhancement.Methods:In accordance with Preferred Reporting Items for Systemic Review and Meta-Analyses guidelines,we systematically searched PubMed,Embase,CINAHL,and Cochrane databases.Studies were categorized according to the type of simulation models investigated.Results:We identified 238 unique references,with 55 studies ultimately meeting inclusion criteria.Of these,19 studies described cadaveric dissection models,17 discussed three-dimensional(3D)printed models,14 examined virtual surgical planning and augmented reality-based models,and five 5 articles described task trainers.Conclusions:There are a wide variety of simulation models for endoscopic skull base surgery,including high-fidelity cadaveric,virtual reality,and 3D-printed models.These models are an asset for trainee development and preoperative surgical preparation.
基金Supported by the National Natural Science Foundation of China(51374242,51504286)China Postdoctoral Science Foundation(2015M572270)the Fundamental Research Funds for the Central Universities of Central South University(2015zzts079)
文摘To simulate the rumor propagation process on online social network during emergency, a new rumor propagation model was built based on active immune mechanism. The rumor propagation mechanisms were analyzed and corresponding parameters were defined. BA scale free network and NW small world network that can be used for representing the online social network structure were constructed and their characteristics were compared. Agent-based simulations were conducted on both networks and results show that BA scale free network is more conductive to spreading rumors and it can facilitate the rumor refutation process at the same time. Rumors paid attention to by more people is likely to spread quicker and broader but for which the rumor refutation process will be more effective. The model provides a useful tool for understanding and predicting the rumor propagation process on online social network during emergency, providing useful instructions for rumor propagation intervention.
文摘The use of virtual simulation-based training continues to expand, as organizations explore alternative methods to reduce the cost of training. While virtual simulation has been empirically validated to be effective in the transfer of skills to the live environment, what is still unknown is what effect, if any, that an individual’s sense of presence in the simulation has on their performance. In this paper, we examine the relationship between presence and performance while performing a psychomotor task in a virtual environment. The independent variables were visual display and expertise level. The dependent variables were presence and performance. We found evidence of a moderate relationship between the degree of presence experienced in the simulation and an individual’s performance over three training trials. Results of this study may inspire future research to investigate whether higher presence in virtual simulation results in higher performance.
基金Project(51008229)supported by the National Natural Science Foundation of ChinaProject supported by Key Laboratory of Road and Traffic Engineering of Tongji University,China
文摘A simulation model was proposed to investigate the relationship between train delays and passenger delays and to predict the dynamic passenger distribution in a large-scale rail transit network. It was assumed that the time varying original-destination demand and passenger path choice probability were given. Passengers were assumed not to change their destinations and travel paths after delay occurs. CapaciW constraints of train and queue rules of alighting and boarding were taken into account. By using the time-driven simulation, the states of passengers, trains and other facilities in the network were updated every time step. The proposed methodology was also tested in a real network, for demonstration. The results reveal that short train delay does not necessarily result in passenger delays, while, on the contrary, some passengers may get benefits from the short delay. However, large initial train delay may result in not only knock-on train and passenger delays along the same line, but also the passenger delays across the entire rail transit network.
基金funded in part by the Advanced Research Projects AgencyEnergy (ARPA-E), U.S. Department of Energy, under award number DE-AR0001471。
文摘Although train modeling research is vast, most available simulation tools are confined to city-or trip-scale analysis, primarily offering micro-level simulations of network segments. This paper addresses this void by developing the Ne Train Sim simulator for heavy long-haul freight trains on a network of multiple intersecting tracks. The main objective of this simulator is to enable a comprehensive analysis of energy consumption and the associated carbon footprint for the entire train system. Four case studies were conducted to demonstrate the simulator's performance. The first case study validates the model by comparing Ne Train Sim output to empirical trajectory data. The results demonstrate that the simulated trajectory is precise enough to estimate the train energy consumption and carbon dioxide emissions. The second application demonstrates the train-following model considering six trains following each other. The results showcase the model ability to maintain safefollowing distances between successive trains. The next study highlights the simulator's ability to resolve train conflicts for different scenarios. Finally, the suitability of the Ne Train Sim for modeling realistic railroad networks is verified through the modeling of the entire US network and comparing alternative powertrains on the fleet energy consumption.
基金supported by the National Natural Science Foundation of China (No. 51007074)the Program for New Century Excellent Talents in University(NECT-08-0825)+1 种基金the Research and Development Project of the National Railway Ministry (2011J016-B)The basic research universities special fund operations(SWJTU11CX141)
文摘The on-board diagnosis network is the nervous system of high-speed Maglev trains, connecting all controller sensors, and corresponding devices to realize the information acquisition and control. In order to study the on-board diagnosis network＇s security and reliability, a simulation model for the on-board diagnosis network of high-speed Maglev trains with the optimal network engineering tool （OPNET） was built to analyze the network＇s performance, such as response error and bit error rate on the network load, throughput, and node-state response. The simulation model was verified with an actual on-board diagnosis network structure. The results show that the model results obtained are in good agreement with actual system performance and can be used to achieve actual communication network optimization and control algorithms.
文摘Simulating large-scale and complex systems is commonly considered a difficult and time-consuming task. In this paper, we propose a partial simulation way to speed up the simulation with real time demands. It is based on the idea that a train traffic diagram is expressed in a network, and through calculating the maximal long path in the network the simulation is done, but only within a particular partial area.Upon this, we let it become a problem oriented simulation. The simulation could be started at any time,from any trains or at any stations and stopped as the same way according to the problem to be concerned.We can use this kind of simulation to analyse or confirm the correctness of traffic schedule at a high speed to meet the real time demands.
基金Supported by the National Natural Science Foundation of China under Grant No. 70901006Research Foundation of Beijing Jiaotong University under Grant Nos. 2011JBM158, 2011JBM162Research Foundation of State Key Laboratory of Rail Traffic Control and Safety under Grant Nos. RCS2009ZT001, RCS2010ZZ001
文摘Based on the discrete time method, an effective movement control model is designed for a group of high- speed trains on a rail network. The purpose of the model is to investigate the specific traffic characteristics of high-speed trains under the interruption of stochastic irregular events. In the model, the high-speed rail traffic system is supposed to be equipped with the moving-block signalling system to guarantee maximum traversing capacity of the railway. To keep the safety of trains＇ movements, some operational strategies are proposed to control the movements of trains in the model, including traction operation, braking operation, and entering-station operation. The numerical simulations show that the designed model can well describe the movements of high-speed trains on the rail network. The research results can provide the useful information not only for investigating the propagation features of relevant delays under the irregular disturbance but also for rerouting and reseheduling trains on the rail network.
基金supported by the National Natural Science Foundation of China under grant 42271448by the Key Laboratory of Land satellite Remote sensing Application,Ministry of Natural Resources of the People’s Republic of China(Grant No.KLSMNR-G202317).
文摘Traditional algorithms do not fully utilize the timing information of non-cooperative targets,and setting too many motion parameters can lead to complex dynamic model calculations.This paper proposes a long short-term memory(LSTM)network-based method for estimating the parameters of the active segment of the non-cooperative target under single-satellite observation.Based on the simulation training set of the active segment of the non-cooperative target,the network parameters of the LSTM network are designed,the motion characteristics of the active segment of the non-cooperative target are fully excavated through data-driven methods,and the candidate cutting trajectories are screened and predicted to realize the estimation of the motion parameters of the active segment of the non-cooperative target under the condition of single-satellite observation.The experimental results show that the estimation method proposed in this paper can effectively deal with the inaccurate problem with the non-cooperative target’s active segment motion model established under the condition of single-satellite observation,obtain more accurate active segment motion parameters,and provide a feasible new idea and method for the parameter estimation of the active segment of the non-cooperative target under the single-satellite observation.
