simulation

摘要： 运用有限元分析软件Solidworks Simulation对行星齿轮减速机的大行星架进行结构强度分析。分析结果表明,其在典型工况下的强度满足使用要求,但大部分结构的应力远低于材料强度,富余量较大,可以进行轻量化设计。在分析结果的指导下,对大行星架结构进行优化,在满足强度要求的前提下减轻大行星架质量,此方法对类似产品的轻量化设计提供了有益的参考。

摘要： BACKGROUND: A national standardized emergency medicine(EM) curriculum for medical students, including specific competencies in procedural skills, are absent in many countries. The development of an intensive simulating training program in EM, based on a tight schedule, is anticipated to enhance the competency of medical students.METHODS: A 3-day intensive EM training program, consisting of four procedural skills and 8-hour case-based learning(CBL), was developed by experienced physicians from the EM department in Peking Union Medical College Hospital(PUMCH). Medical students from Peking Union Medical College(PUMC) and Tsinghua University(THU) participated in the training. Three written tests were cautiously designed to examine the short-term(immediately after the program) and long-term(6 months after the program) efficacy of the training. After completion of the training program, an online personal appraisal questionnaire was distributed to the students on WeChat(a mobile messaging App commonly used in China) to achieve anonymous self-evaluation.RESULTS: Ninety-seven out of 101 students completed the intensive training and took all required tests. There was a significant increase in the average score after the intensive simulating training program(pre-training 13.84 vs. 15.57 post-training, P<0.001). Compared with the pre-training test, 63(64.9%) students made progress. There was no significant difference in scores between the tests taken immediately after the program and 6 months later(15.57±2.22 vs. 15.38±2.37, P=0.157). Students rated a higher score in all diseases and procedural skills, and felt that their learning was fruitful.CONCLUSIONS: The introduction of a standardized intensive training program in EM focusing on key competencies can improve clinical confidence, knowledge, and skills of medical students toward the specialty. In addition, having such a program can also enhance student’s interest in EM as a career choice which may enhance recruitment into the specialty and workplace planning.

摘要： Subjecting a normal mechanical vibration to a cooling slope plate,is a proposed method for preparing semisolid nondendritic slurry,named shear-vibration coupling sub-rapid solidification(SCS).Taking Al-8Si alloy as model material,the temperature field and distribution field of solid or liquid phase during SCS were simulated using COMSOL Multiphysics software to primarily choose the optimal processing parameters.Subsequently,the slurries were prepared with the parameters selected according to the simulation results and the microstructures of the slurries were experimentally investigated.Results indicate that the simulation results could provide a basis for roughly choosing the processing parameters,although the calculated solid fractions are always higher than the experimental ones.The processing parameters affect the primary grain size,shape factor and solid fraction mainly through altering the contact duration of melt on the plate,and thus affecting the cooling effect on the melt,nucleation rate,and grain dissociation and proliferation.Experiments with optimized processing parameters show that the primary grains in the slurry have an average size of about 32μm and shape factor of 1.38,and are quite uniform,even at the highest pouring rate of 2.81 kg·s^(-1),the size and shape factor are about 46μm and 1.7,respectively,which implies that the proposed SCS is a promising technology for efficient fabrication of high-quality Al slurry available for engineering applications.

摘要： BACKGROUND: Transesophageal echocardiography(TEE) is used in the emergency department to guide resuscitation during cardiac arrest. Insertion of a TEE transducer requires manual skill and experience, yet in some residency programs cardiac arrest is uncommon, so some physicians may lack the means to acquire the manual skills to perform TEE in clinical practice. For other infrequently performed procedural skills, simulation models are used. However, there is currently no model that adequately simulates TEE transducer insertion. The aim of this study is to evaluate the feasibility and efficacy of using a cadaveric model to teach TEE transducer placement among novice users.METHODS: A convenience sample of emergency medicine residents was enrolled during a procedure education session using cadavers as tissue models. A pre-session assessment was used to determine prior knowledge and confidence regarding TEE manipulation. Participants subsequently attended a didactic and hands-on education session on TEE placement. All participants practised placing the TEE transducer until they were able to pass a standardized assessment of technical skill(SATS). After the educational session, participants completed a post-session assessment. RESULTS: Twenty-five residents participated in the training session. Mean assessment of knowledge improved from 6.2/10 to 8.7/10(95% confidence interval [CI] of knowledge difference 1.6–3.2, P<0.001) and confidence improved from 1.6/5 to 3.1/5(95% CI of confidence difference 1.1–2.0, P<0.001). There was no relationship between training level and the delta in knowledge or confidence.CONCLUSIONS: In this pilot study, the use of a cadaveric model to teach TEE transducer placement methods among novice users is feasible and improves both TEE manipulation knowledge and confidence levels.

摘要： To better utilize the infrared(IR)region in sunlight for photovoltaic devices(PVs),upconversion nanoparticles(UCNPs)have been proposed to improve power conversion efficiency(PCE).However,researchers recently have found that the upconversion(UC)effect is negligible in PVs performance improvement for their ultra-low UC photoluminescence quantum yields of UCNPs solid film,while the real mechanism of UCNPs in PVs has not been clearly studied.Herein,based on the material inorganic perovskitesγ-CsPbI_(3),NaYF_(4):20%Yb^(3+),2%Er^(3+)UCNPs were integrated into different transport layer to optimize device performance.Compared with reference device,the short-circuit current density and PCE of optimized device reached 20.87 mA/cm^(2)(20.39 mA/cm^(2))and 18.34%(17.72%),respectively,without sacrificing open-circuit voltage and filling factor.Further experimental characterizations verified that the improved performance was attributable to enhanced visible light absorption instead of IR.To theoretically explain the statement,the light field distribution in device was simulated and the absorption in different layers was calculated.The results revealed that the introduction of UCNPs with different refractive index from other layers caused light field disturbance,and improved visible light captured by γ-CsPbI_(3).Importantly,through experiments and theoretical calculation,the research deeply explored the potential mechanism of UCNPs in optimizing PVs performance.

摘要： Thin Layer Activation is a nuclear technique that has key advantages over other wear measuring techniques for mechanical systems,especially for in site experiments on equipment important to safety in nuclear plants.Still,it incurs radioactive dose and,thus,must be proved radiologically safe before use,otherwise,the utilization of this technique may be hindered inviable.Proving said technique is safe previous to any operational/monetary cost is key,providing a methodology for this early assertion is the main contribution of this work—here,only non-occupationally exposed individuals are considered.This work offers a methodology,through a case study,to ascertain the Thin Layer Activation parameters to obtain safe levels of radioactive dose while maintaining statistically reliable results.This methodology consists of using simulations,through the Monte Carlo Method,to obtain the floors and ceilings for the previously mentioned activation parameters based on operation and work conditions on site.

摘要： This paper dwells upon optimizing the azimuth samp-ling interval of digital surface maps used to model radar ground clutter.The resulting equations can be used to find the digital map sampling interval for the required calculation error and modeled power of the simulated signal,which determines the resulting distribution of backscatter intensity.The paper further showcases how the sampling interval could be increased by pre-processing the map.

摘要： BACKGROUND:Diverse models of automated external defibrillators(AEDs)possess distinctive features.This study aimed to investigate whether laypersons trained with one type of AED could intelligently use another initial contact type of AED with varying features.METHODS:This was a prospective crossover simulation experimental study conducted among college students.Subjects were randomly trained with either AED1(AED1 group)or AED2(AED2 group),and the AED operation performance was evaluated individually(Phase I test).At the 6-month follow-up AED performance test(Phase II test),half of the subjects were randomly switched to use another type of AED,which formed two switches(Switch A:AED1-1 group vs.AED2-1 group;Switch B:AED2-2 group vs.AED1-2 group).RESULTS:A total of 224 college students participated in the study.In the phase I test,a significantly higher proportion of successful defibrillation and shorter shock delivery time to achieve successful defibrillation was observed in the AED2 group than in the AED1 group.In the phase II test,no statistical differences were observed in the proportion of successful defibrillation in Switch A(51.4%vs.36.6%,P=0.19)and Switch B(78.0%vs.53.7%,P=0.08).The median shock delivery time within participants achieving successful defibrillation was significantly longer in the switched group than that of the initial group in both Switch A(89[81-107]s vs.124[95-135]s,P=0.006)and Switch B(68[61.5-81.5]s vs.95.5[55-131]s,P<0.001).CONCLUSION:College students were able to effectively use AEDs different from those used in the initial training after six months,although the time to shock delivery was prolonged.

摘要： Aiming at the position and attitude tracking of coaxial rotor aircraft(CRA),this paper proposes a combinatorial control method of sliding mode control(SMC)coupled with proportional-integralderivative control(PIDC).Considering the complete description of flight dynamics,aerodynamics and airflow interference,the dynamical model of CRA is established.The dynamical model is simplified according to the actual flight,then the simplified dynamical model is divided into two subsystems:a fully-actuated subsystem and an under-actuated subsystem.The controller of the fully-actuated subsystem consists of a SMC controller coupled with a rate bounded PIDC controller,while the controller of the under-actuated subsystem is composed of a SMC controller.The sliding manifold is defined by combining the position and velocity tracking errors of the state variables for each subsystem.Lyapunov stability theory is used to verify the stability of the sliding mode controller,which ensures that all state trajectories of the system can reach and stay on the sliding mode surface,the uncertainty and external interference of the model are compensated.Simulation and experiment compared with the conventional PIDC are carried out,the results demonstrate the effectiveness and the robustness of the proposed control method of this paper.

摘要： 针对风电轴承滚道热处理,设计了一种45kW并联谐振感应加热电源电路。首先,对电源结构及并联谐振等效电路进行分析,确定电路设计组成;其次,采用基于神经网络PID的闭环反馈策略,改变直流侧电压,实现功率调节;最后,为验证并联谐振感应加热电源电路的有效性,建立了SimuLation模型,模拟仿真电源功率输出。研究结果表明:设计的感应加热电源电路,用于风电轴承滚道热处理,输出功率稳定,符合设计要求。

摘要： EMAT is short for Electro-Magnetic Acoustic Trans-ducer. It’s a new device for acoustic emission and receiv-ing. It has many advantages such as noncontact the ma-terial being tested directly in process of testing. It doesn’tneed couple agent, and has high speed testing and goodrepeatability, and performs well at high temperature, andis suitable to test material with special shape, and so on.This paper describes a simulation based on the electromagnetic ultrasonic pulse discharge experi-ment. Selecting each experimental parameter by the way of theory and Pspice simulate excitation signal. Fi-nally, simulation results obtained are consistent with the theoretical conclusions.

摘要： In order to secure high strength and high elongation of suspension parts，it is very important to predictshrinkage porosity quantitatively．A new simulation method for quantitative prediction of shrinkage porosity when replenishing molten metal has been proposed for squeeze casting process．To examine the adequacy of the calculation model，the proposed method was applied to a plate model．

摘要： The penicillin fermentation process is a complicate biochemical system with time varying, nonlinear anduncertainty feature. Since some important parameters can't be measured online and the metabolizing routes of manybiochemical processes are not well known, it is difficult to obtain its accurate model using routine modeling method. ButRBF neural networks have ability to get nonlinear function and self-study capability. Therefore, RBF neural network wasused to describe penicillin fermentation process in this paper. Simulations were made, and results of the simulation showthat the model is practicable.

摘要： Reliable mine gas prediction is not only essential for effective gas drainage and control，improvement of mining safety and reduction of coal production costs，but also important to mine gas production assessment for gas utilisation evaluation and planning．An integrated mine gas simulation system has been developed to predict strata conditions and methane gas emission during longwall mining．The system is used to assist selection and planning of suitable mining，gas management and utilisation strategies for new and existing mines．Several key mine gas assessment processes，such as mine site gas and geotechnical characterisation,and fully coupled mechanical deformation-fluid flow computer simulation，have been integrated in the simulation system．Gas flow during mining is controlled by in situ gas content and geotechnical conditions，as well as the mining induced changes in the strata such as those of stress，fracture，pore pressure and permeability.The central part of the integrated simulation system is the new 3D code called COSFLOW that simulates the complex behaviour of rock，water and gas flow，and predicts gas emission during longwall development and retreat．The code is also capable of simulating gas drainage performance and estimating gas production．This system was developed from a recently completed collaborative project entitled “Predevelopment Studies for Mine Methane Management and Utilisation”，between the New Energy and Industrial Technology Development Organization (NEDO) of Japan，the Japan Coal Energy Center (JCOAL)，and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) of Australia．The integrated simulation approach is described in this paper and examples of mine site application are presented．

摘要： In the study of CCS and related process calculi, there are two standard approaches to the definition of similarity or equivalence of processes. The first is bisimulation, an equivalence relation based on the structural operational semantics of the calculus. It has simulation as an asymmetric variant. The second is refinement, an ordering defined as inclusion of the sets of observations that may be made of the behaviour of each process. The original forms of bisimulation (strong and weak) were intended to give the strongest reasonable definition of process expressions.This paper shows how to define a process calculus in which the concepts of simulation and refinement coincide with each other : thus the combined benefits of two approaches are available uniformly to all applications.

摘要： developed for the trajectory tracking of robot manipulators with parameter uncertainty and outside disturbance. A functional-link neural network is used to approximate a unknown function. And a new network weight tuning law is given which is different to the existing σ-modification method. The proposed robust neural network controller based on this new tuning law can guarantee not only the boundedness of network weight but also the asymptotic stability of the tracking error. The numerical experiment shows that the proposed method is feasible and efficient.

摘要： developed for the trajectory tracking of robot manipulators with parameter uncertainty and outside disturbance. A functional-link neural network is used to approximate a unknown function. And a new network weight tuning law is given which is different to the existing σ-modification method. The proposed robust neural network controller based on this new tuning law can guarantee not only the boundedness of network weight but also the asymptotic stability of the tracking error. The numerical experiment shows that the proposed method is feasible and efficient.

摘要： developed for the trajectory tracking of robot manipulators with parameter uncertainty and outside disturbance. A functional-link neural network is used to approximate a unknown function. And a new network weight tuning law is given which is different to the existing σ-modification method. The proposed robust neural network controller based on this new tuning law can guarantee not only the boundedness of network weight but also the asymptotic stability of the tracking error. The numerical experiment shows that the proposed method is feasible and efficient.

摘要： developed for the trajectory tracking of robot manipulators with parameter uncertainty and outside disturbance. A functional-link neural network is used to approximate a unknown function. And a new network weight tuning law is given which is different to the existing σ-modification method. The proposed robust neural network controller based on this new tuning law can guarantee not only the boundedness of network weight but also the asymptotic stability of the tracking error. The numerical experiment shows that the proposed method is feasible and efficient.

摘要： developed for the trajectory tracking of robot manipulators with parameter uncertainty and outside disturbance. A functional-link neural network is used to approximate a unknown function. And a new network weight tuning law is given which is different to the existing σ-modification method. The proposed robust neural network controller based on this new tuning law can guarantee not only the boundedness of network weight but also the asymptotic stability of the tracking error. The numerical experiment shows that the proposed method is feasible and efficient.

摘要： 本发明公开了一种基于SolidWorks Flow Simulation的SiC功率分析方法，包括SiC芯片晶元，所述SiC芯片晶元的底部设有覆铜陶瓷基板，所述覆铜陶瓷基板的底部设有焊接层，所述焊接层的底部设有散热器，所述散热器的底部设有水道壳体，所述水道壳体的两端均进水口管道，所述水道壳体的内部设有冷却液网格控制体积。本发明利用嵌入于三维设计软件SolidWorks中的SolidWorks Flow Simulation直接进行仿真分析，与三维设计软件无缝连接，避免三维模型的导入和导出，本发明通过网格精度级别设置，寻求求解精度和效率间的平衡点，网格无需手动划分，由软件自动划分，且仿真计算结果精度较高，完全适用于工业应用场合，同时流程固定，求解的收敛性好，仿真过程稳定。

摘要： 本发明提供了一种基于Simulation铁道机车车辆轮轴过盈装配接触应力分析方法。本发明技术方案如下：以CRH2型动车组拖车轮对为雏形，利用SolidWorks软件建立轮轴过盈装配三维数字化模型；将轮轴过盈装配三维模型转换到SolidWorks有限元分析模块Simulation中，建立其有限元模型；设定轮对轮轴过盈装配相接触面组为冷缩配合的接触方式，进行过盈接触应力分析；等差选定若干个规定范围内不同轮轴过盈量值进行分析处理。以多次有限元分析数据为基础，对比轮轴材料屈服强度极限，判断说明该过盈量范围的合理性与可靠性，同时确定该车型轮轴过盈装配过盈量—应力函数模型。