Digital Twin Modeling and Simulation Optimization of Transmission Front and Middle Case Assembly Line

As the take-off of China’s macro economy,as well as the rapid development of infrastructure construction,real estate industry,and highway logistics transportation industry,the demand for heavy vehicles is increasing rapidly,the competition is becoming increasingly fierce,and the digital transformation of the production line is imminent.As one of themost important components of heavy vehicles,the transmission front andmiddle case assembly lines have a high degree of automation,which can be used as a pilot for the digital transformation of production.To ensure the visualization of digital twins(DT),consistent control logic,and real-time data interaction,this paper proposes an experimental digital twin modeling method for the transmission front and middle case assembly line.Firstly,theDT-based systemarchitecture is designed,and theDT model is created by constructing the visualization model,logic model,and data model of the assembly line.Then,a simulation experiment is carried out in a virtual space to analyze the existing problems in the current assembly line.Eventually,some improvement strategies are proposed and the effectiveness is verified by a new simulation experiment.

Computer-based simulative training system--a new approach to teaching pre-hospital trauma care

Objective:A computer-based STS(simulative training system) in providing pre-hospital trauma care at a disaster site was applied to teaching nursing students in the Second Military Medical University,China.This article reports on the teaching effectiveness of this system.Methods:Among 92 participants,46 were in the study group and 46 were in the 'control' group. Each student completed a multiple-choice quiz after completing 18 hours(six three-hour sessions) of the study module,and a score was recorded.The simulative training module was completed only by the study group;the 'control' group was assigned in-class discussions for the same amount of time covering the same content as the study group.The final course scores,which included both comprehensive and group task-based tests were compared between these two groups.The study used a descriptive and comparative approach for quantitative data analysis.Tests of independency between the multiple choice scores and the simulation scores were also performed.Finally,anonymous surveys were conducted.Results:The study group performed better than the 'control' group with a significantly higher average score for the group scenario task-based test score,and consequently the study group's final course score was significantly higher than the 'control' group.As per chi-square tests,no significant associations were found between the multiple choice scores and the simulated training scores.The final surveys showed students overwhelmingly agreed that STS training improved their knowledge and skills,their ability to recognize a potential critical event, and their initial response for trauma care at pre-hospital settings.The survey responses of the study group were noteworthy as they indicated that students recognized the importance of simulative training,appreciated the realism of the simulation,and were able to fight/adjust to the stressful feelings in order to focus on the task.Conclusion:Computer-based STS may be an effective teaching model to help students improve their capability in providing pre-hospital trauma care,and in their effectiveness in disaster response.

Numerical simulation of the anti-shock performance of a gear case

Both sea battles and testing of ship in underwater explosions reveal unacceptably poor anti-shock performance of important shipboard equipment. Anti-shock performance of shipboard equipment is a significant factor determining fighting strength and survivability. The anti-shock performance of a shipboard gear case based on BV043/85 was investigated using numerical simulation. A geometric model of the gear case was built using MDT software and meshed in HyperMesh software, and then the finite element model of the gear case was formed. Using ABAQUS software, the anti-shock performance of the gear case was simulated. First, shock response of typical regions of gear case was determined. Next, some generalizations were made about the anti-shock performance of the gear case by analyzing the Mises stress of typical regions varied with shock inputs. Third, weak regions were determined from simulation results. The threshold values of shock resistance of the gear case at different impulse widths were obtained through interpolating the numerical simulation results selected from the most dangerous spot. This research provides a basis for further optimization of the design of gear cases.

The Finite Element Analysis and Computer Simulation of the Composite Case

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AN INTEGRATION METHOD WITH FITTING CUBIC SPLINE FUNCTIONS TO A NUMERICAL MODEL OF 2ND-ORDER SPACE-TIME DIFFERENTIAL REMAINDER——FOR AN IDEAL GLOBAL SIMULATION CASE WITH PRIMITIVE ATMOSPHERIC EQUATIONS

In this paper,the forecasting equations of a 2nd-order space-time differential remainder are deduced from the Navier-Stokes primitive equations and Eulerian operator by Taylor-series expansion.Here we introduce a cubic spline numerical model(Spline Model for short),which is with a quasi-Lagrangian time-split integration scheme of fitting cubic spline/bicubic surface to all physical variable fields in the atmospheric equations on spherical discrete latitude-longitude mesh.A new algorithm of"fitting cubic spline—time step integration—fitting cubic spline—……"is developed to determine their first-and2nd-order derivatives and their upstream points for time discrete integral to the governing equations in Spline Model.And the cubic spline function and its mathematical polarities are also discussed to understand the Spline Model’s mathematical foundation of numerical analysis.It is pointed out that the Spline Model has mathematical laws of"convergence"of the cubic spline functions contracting to the original functions as well as its 1st-order and 2nd-order derivatives.The"optimality"of the 2nd-order derivative of the cubic spline functions is optimal approximation to that of the original functions.In addition,a Hermite bicubic patch is equivalent to operate on a grid for a 2nd-order derivative variable field.Besides,the slopes and curvatures of a central difference are identified respectively,with a smoothing coefficient of 1/3,three-point smoothing of that of a cubic spline.Then the slopes and curvatures of a central difference are calculated from the smoothing coefficient 1/3 and three-point smoothing of that of a cubic spline,respectively.Furthermore,a global simulation case of adiabatic,non-frictional and"incompressible"model atmosphere is shown with the quasi-Lagrangian time integration by using a global Spline Model,whose initial condition comes from the NCEP reanalysis data,along with quasi-uniform latitude-longitude grids and the so-called"shallow atmosphere"Navier-Stokes primitive equations in the spherical coordinates.The Spline Model,which adopted the Navier-Stokes primitive equations and quasi-Lagrangian time-split integration scheme,provides an initial ideal case of global atmospheric circulation.In addition,considering the essentially non-linear atmospheric motions,the Spline Model could judge reasonably well simple points of any smoothed variable field according to its fitting spline curvatures that must conform to its physical interpretation.

Three-dimensional image simulation of primary diaphragmatic hemangioma: A case report

BACKGROUND Fewer than 200 cases of diaphragmatic tumors have been reported in the past century. Diaphragmatic hemangiomas are extremely rare. Only nine cases have been reported in English literature to date. We report a case of cavernous hemangioma arising from the diaphragm. Pre-operative three-dimensional(3D)simulation and minimal invasive thoracoscopic excision were performed successfully, and we describe the radiologic findings and the surgical procedure in the following article.CASE SUMMARY A 40-year-old man was referred for further examination of a mass over the right basal lung without specific symptoms. Contrast-enhanced computed tomography revealed a poorly-enhanced lesion in the right basal lung, abutting to the diaphragm, measuring 3.1 cm × 1.5 cm in size. The mediastinum showed a clear appearance without evidence of abnormal mass or lymphadenopathy. A preoperative 3D image was reconstructed, which revealed a diaphragmatic lesion. Video-assisted thoracic surgery was performed, and a red papillary tumor was found, originating from the right diaphragm. The tumor was resected, and the pathological diagnosis was cavernous hemangioma.CONCLUSION In this rare case of diaphragmatic hemangioma, 3D image simulation was helpful for the preoperative evaluation and surgical decision making.

Numerical simulation of optimum mining design for high stress hard-rock deposit based on inducing fracturing mechanism

The 3D numerical simulation model of deep hard-rock deposit in Kaiyang Phosphate Mine of Guiyang was established based on the practical engineering using 3DEC numerical simulation software. The distribution characteristics of displacement fields and plastic zones of the orebody were simulated in three different excavation cases, including the case of excavation artificial inducted roadway in the orebody, the case of horizontal or vertical excavation direction and the case of the upward or downward excavation order. The simulation results indicate that the plastic zone and displacement field of surrounding rock around the inducted roadway are continuously increasing with the increase of the exposure time after digging an artificial inducted roadway in the orebody. Thus the raw rock ore becomes easier to be fragmented, which provides advantageous conditions for roadheader to cut high stress hard-rock. It is worthy noting that there is a large difference in effective utilization of deep ground pressure between horizontal and vertical excavation directions. The later can produce larger deformation and fracture zone than the former on the rock mass around the deduced roadway, which means that the later may utilize the high ground pressure more effectively to break hard-rock. And the obtained results also show that upward excavation order is more helpful for ground pressure to break rock than downward excavation order.

Three-Dimensional Finite Element Numerical Simulation and Physical Experiment for Magnetism-Stress Detecting in Oil Casing

The casing damage has been a big problem in oilfield production. The current detection methods mostly are used after casing damage, which is not very effective. With the rapid development of China's offshore oil industry, the number of offshore oil wells is becoming larger and larger. Because the cost of offshore oil well is very high, the casing damage will cause huge economic losses. What's more, it can also bring serious pollution to marine environment. So the effective methods of detecting casing damage are required badly. The accumulation of stress is the main reason for the casing damage. Magnetic anisotropy technique based on counter magnetostriction effect can detect the stress of casing in real time and help us to find out the hidden dangers in time. It is essential for us to prevent the casing damage from occurring. However, such technique is still in the development stage. Previous studies mostly got the relationship between stress and magnetic signals by physical experiment, and the study of physical mechanism in relative magnetic permeability connecting the stress and magnetic signals is rarely reported. The present paper uses the ANSYS to do the three-dimensional finite element numerical simulation to study how the relative magnetic permeability works for the oil casing model. We find that the quantitative relationship between the stress' s variation and magnetic induction intensity's variation is: Δδ =K* ΔB, K = 8.04×109, which is proved correct by physical experiment.

Collaborative Simulation and Testing of the Superconducting Dipole Prototype Magnet for the FAIR Project

The superconducting dipole prototype magnet of the collector ring for the Facility for Antiproton and Ion Research （FAIR） is an international cooperation project. The collaborative simulation and testing of the developed prototype magnet is presented in this paper. To evaluate the mechanical strength of the coil case during quench, a 3-dimensional （3D） electromagnetic （EM） model was developed based on the solid97 magnetic vector element in the ANSYS commercial software, which includes the air region, coil and yoke. EM analysis was carried out with a peak operating current at 278 A. Then, the solid97 element was transferred into the solid185 element, the coupled analysis was switched from electromagnetic to structural, and the finite element model for the coil case and glass-fiber reinforced composite （G10） spacers was established by the ANSYS Parametric Design Language based on the 3D model from the CATIA V5 software. However, to simulate the friction characteristics inside the coil case, the conta173 surface-to-surface contact element was established. The results for the coil case and G10 spacers show that they are safe and have sufficient strength, on the basis of testing in discharge and quench scenarios.

Erosion characteristics and simulation charts of sand fracturing casing perforation

Large-scale sand fracturing is a necessary means in the efficient exploitation of shale gas/oil.However,in the process of fracturing operation,the sand carrying fluid and proppant easily causes scouring and wear to production strings,especially the casing perforation system,which damage the wellbore integrity and deformation to affect the subsequent fracturing.For this problem,taking the actual construction conditions and perforation technology of an oilfield in western China as an example,the structural parameters of the downhole string were measured and the wall thickness reduction model of casing perforation suitable for large-displacement sand fracturing in horizontal well section was established.With software ANSYS-FLUENT,the casing perforation erosion under the conditions of different displacements,sand content and perforation sand-passing quantity in the process of sand fracturing was simulated and calculated.The influences of three parameters on perforation erosion and expansion were analyzed and the prediction chart of the influences of three main control factors on perforation erosion and expansion was established.The perforation erosion images after fracturing construction were obtained with the downhole eagle perforation logging technology.The logging chart results were compared with the downhole eagle perforation data.The error between the established numerical simulation calculation charts and the real logging data was about 5%,indicating that the simulation charts were the valuable reference.

Performance of a Combined Energy System Consisting of Solar Collector, Biogas Dry Reforming and Solid Oxide Fuel Cell: An Indian Case Study

An energy production system consisting of a solar collector, biogas dry reforming reactor and solid oxide fuel cell (SOFC) was assumed to be installed in Kolkata, India. This study aims to understand the impact of climate conditions on the performance of solar collectors with different lengths of parabolic trough solar collector (dx) and mass flow rate of heat transfer fluid (m). In addition, this study has evaluated the amount of H2 produced by biogas dry reforming (GH2), the amount of power generated by SOFC (PSOFC) and the maximum number of possible households (N) whose electricity demand could be met by the energy system proposed, considering the performance of solar collector with the different dx and m. As a result, the optimum dx was found to be 4 m. This study revealed that the temperature of heat transfer fluid (Tfb) decreased with the increase in m. Tfb in March, April and May was higher than that in other months, while Tfb from June to December was the lowest. GH2, PSOFC and N in March, April and May were higher than those in other months, irrespective of m. The optimum m was 0.030 kg/s.

基于AMESim/Simulink的“电液控制工程”教学案例应用

针对“电液控制工程”课程电液知识融合、理论性强、概念抽象等特点,将教学与科研相结合,以工程实例作为教学案例,引入AMESim/Simulink虚拟仿真实验,应用互联网技术,采用线上线下混合教学模式进行教学设计。教学实践表明:这种案例教学方法有助于培养和促进学生主动学习,体现了以学生为中心的教育理念,有助于学生掌握电液控制的工作原理及系统设计方法,培养学生解决问题的能力和创新能力,提高学生在就业中的竞争力。

基于程序变异的Simulink模型测试方法

为解决当前Simulink模型变异测试中测试执行开销大、测试用例生成效率低等问题,首先根据当前的Simulink模型变异算子集,基于程序变异技术提出了Simulink模型的变异测试过程和一组改进变异算子集.实验表明,在不影响测试用例集变异评分的情况下,该组变异算子集能够有效减少变异模型的生成数量,从而降低测试开销.其次,设计了一种基于搜索的Simulink模型变异测试用例生成方法,该方法将变异模型的测试用例生成问题转换为目标函数极小化问题,通过模拟退火算法对目标函数寻优,最终搜索出能够杀死该变异模型的测试用例.最后,将该方法应用于典型案例,验证了方法的正确性和有效性.

Numerical study on the case effect of a bomb air explosion

When considering the bomb explosion damage effect,the air shock wave and high-speed fragments of the bomb case are two major threats.In experiments,the air shock wave was studied by the bare explosives superseding the real cased bomb;in contrast,the bomb case influence was ignored to reduce risk.The air explosion simulations of the MK84 warhead with and without the case were conducted.The numerical simulation results showed that the bomb case significantly influenced the shock wave generated by the bomb:the spatial distribution of shock wave in the near field changed,and the peak value of shock wave was reduced.Breakage of the case and kinetic energy of the fragmentation consumed 3 and 38% of the explosion energy,respectively.The increasing factors of the peak overpressure induced by the bare explosive on the ground and in the air were 1.43-3.04 and 1.37-1.57,respectively.Four typical stages of case breakage were defined.The mass distribution of the fragments follows the Mott distribution.The initial velocity distribution of the fragments agreed well with the Gurney equation.

电力电子技术O2O教学与SIMULINK仿真的结合

探讨在电力电子技术教学中引入SIMULINK仿真环境作为O2O教学在线教学的一部分的重要性.O2O教学模式突破了传统教学方法的局限,更好地利用了学生的业余时间.由于SIMULINK仿真环境易于掌握,通过简单的教学视频学习,学生可自行完成所学电路的建模与仿真.这种结合方式不仅可以让学生更直观地得到电路工作波形,更有助于对电路工作过程的理解,可显著提高教学效果.

The Impact of Multilateral Imported Cases of COVID-19 on the Epidemic Control in China

While the spread of COVID-19 in China is under control,the pandemic is developing rapidly around the world.Due to the normal migration of population,China is facing the high risk from imported cases.The potential specific medicine and vaccine are still in the process of clinical trials.Currently,controlling the impact of imported cases is the key to prevent new outbreak of COVID-19 in China.In this paper,we propose two impulsive systems to describe the impact of multilateral imported cases of COVID-19.Based on the published data,we simulate and analyze the epidemic trends under different control strategies.In particular,we compare four different scenarios and show the corresponding medical burden.The results can be useful in designing appropriate control strategy for imported cases in practice.

基于Comsol软件的电磁兼容课程案例式教学设计

该文介绍基于Comsol软件的电磁兼容课程案例式教学方法。通过案例教学和仿真,学生将理论知识应用于实际问题,深入理解电磁兼容的概念和原理。通过仿真案例的可视化结果,学生直观地理解电磁辐射和传导,观察不同参数对电磁兼容性的影响。结果表明,仿真案例具有直观性和可视化等优势,同时又有简化模型、缺乏实际操作经验和对计算机的依赖等局限性。在设计仿真案例时,要充分发挥其优势,规避不足,为学生的学习提供实践性、直观性和灵活性,培养学生的工程设计与研发能力。

情景模拟结合CBL对提升产科住院医师医患沟通能力的效果分析

目的探讨在产科住院医师规范化培训(简称住培)中进行情景模拟结合以案例为基础的教学对医患沟通技能培训的效果。方法选取50名在产科规范化培训的住院医师为研究对象。培训前进行学员调查和医患沟通能力SEGUE测评。基于产科住培大纲选择5个典型病例情景,由教师录制5个典型病例病情医患沟通的示范视频,并梳理相关背景知识,在产科住院医师中依次开展培训课程,即视频示范、小组讨论、病例背景知识梳理讲解、分角色演练、演练后反馈和评价以及临床实践。培训后再次进行学员调查和医患沟通能力SEGUE测评。使用配对样本的非参数检验方法评价培训效果。结果情景模拟结合以案例为基础的教学的医患沟通技能培训后,学员医患沟通能力SEGUE测评总分提高[13.00(11.00~16.00)vs.22.00(20.00~24.00)],差异具有统计学意义(Z=-6.159,P<0.001);医患沟通能力SEGUE测评总体合格率提高[36.0%(18/50)vs.98.0%(49/50)],差异具有统计学意义(χ^(2)=43.464,P<0.001)。结论情景模拟结合以案例为基础的教学的医患沟通技能培训可有效提高学员医患沟通能力,调动学员的学习主动性,激发学员内在学习动力,建议在产科住培中纳入此类课程。

页岩气多级压裂断层动态滑移规律研究

泸州页岩气区块开发过程中套管变形现象严重,而多级压裂是诱发断层滑移并导致套管变形的主要因素,但目前缺乏对断层动态滑移演化规律的研究。在分析泸州地区套管变形失效特征和相关性的基础上,考虑水力裂缝沟通并激活断层实际,建立了多级压裂条件下断层滑移动态演化数值模型。研究结果表明:多级压裂导致近井筒位置孔隙压力随压裂逐级增加,有效地应力降低;模拟时间越长、注入点流量越大,断层滑移量越大,而压裂液黏度影响断层滑移量效果弱;断层长度、断层与井筒的夹角与其滑移量关系密切,断层长度越大,断层滑移量越大;断层与井筒夹角在一定范围内越大,断层滑移量越小;水平地应力差较大的地层断层滑移会越明显。研究成果可为页岩气多级压裂过程中控制压裂施工参数提供参考。

情景模拟教学和CBL在麻醉科住院医师培训中的应用

目的对情景模拟教学和案例教学法在麻醉科住院医师规范化培训中的应用效果进行评价。方法选取2021年1月—2023年1月广州中医药大学第一附属医院内的40名麻醉科住院医师为研究对象。随机分为对照组20名,采用传统教学方法,观察组20名,采用情景模拟教学联合案例教学法。对比2组教学效果。结果教学效果评估示,在学习积极性、学习主动性、合作精神、学习态度、沟通能力、专业精神、应变能力等方面,观察组的评分[(92.32±3.55)分、(92.28±3.23)分、(92.33±2.63)分、(93.25±3.35)分、(93.06±3.12)分、(95.45±2.43)分、(89.42±3.05)分]均高于对照组[(86.41±4.12)分、(85.56±3.53)分、(84.35±4.01)分、(85.38±3.46)分、(86.55±3.62)分、(88.68±3.42)分、(84.24±2.59)分],差异有统计学意义(P<0.001)。在理论知识和技术操作上,观察组住院医师规范化培训(简称“住培”)生的成绩得分均高于对照组,差异有统计学意义(P<0.001)。对照组考核评分低于观察组,差异有统计学意义(P<0.001)。对照组的培训总满意度显著低于观察组,差异有统计学意义(P<0.05)。结论麻醉科住院医师规范化培训中应用情景模拟教学和案例教学法取得了较好的教学效果,改善了麻醉科住院医师的学习能力和态度,提高了成绩和技能,增加了对培训工作的满意度。