4D Integration and Evaluation of Electrostatic Force between Two Charged Parallel Plates

Evaluation of electrostatic force between two arbitrary shaped charged objects encounters a six-fold integration. Analytic evaluation of the integral is not conducive and its numeric evaluation is CPU intensive. For two planar objects, the required integration reduces to a four-fold integration;however, it suffers the same two symptoms. In this article, utilizing a discrete method, we evaluate the much needed integration in a fraction of a second. For a special case, we show the output of our approach agrees with its analytic equivalent formulation.

Exploratory Study on the Simulated Police Force Allocation of Shopping Mall Emergency Based on AnyLogic Platform

Due to the rapid development of society,public places,especially large shopping malls,are relatively frequent places for emergencies.Such emergencies not only seriously affect public security and property,but also bring great psychological pressure to citizens.Therefore,this study is of great significance for the exploration and study of public place emergencies.The research object of this study is the public shopping mall.Based on the AnyLogic simulation platform and guided by the relevant principles of social force model,this study utilize the pedestrian storehouse in the platform as the core module to build the simulation environment,and attempts to simulate the police force restraining effect on the overall event and the perpetrators after the occur of emergent incident under different police force allocations.In order to ensure the accuracy of the experimental data,the research team conducted field survey to estimate the average flow of people and the general data of the security personnel in shopping malls,also estimated the rest rain and capture time after repeated experiments.The results indicate that increasing additional police force outside the shopping malls and pre-organizing reasonable patrol routes can obviously facilitate police officers to restrain perpetrators.Meanwhile,it is also clear that the AnyLogic platform can effectively simulate pedestrian movement and interaction behaviour in emergencies.

Evaluation of integration methods for hybrid simulation of complex structural systems through collapse

This study examines the performance of integration methods for hybrid simulation of large and complex structural systems in the context of structural collapse due to seismic excitations. The target application is not necessarily for real-time testing, but rather for models that involve large-scale physical sub-structures and highly nonlinear numerical models. Four case studies are presented and discussed. In the first case study, the accuracy of integration schemes including two widely used methods, namely, modified version of the implicit Newmark with fixed-number of iteration （iterative） and the operator-splitting （non-iterative） is examined through pure numerical simulations. The second case study presents the results of 10 hybrid simulations repeated with the two aforementioned integration methods considering various time steps and fixed-number of iterations for the iterative integration method. The physical sub-structure in these tests consists of a single-degree-of-freedom （SDOF） cantilever column with replaceable steel coupons that provides repeatable highly- nonlinear behavior including fracture-type strength and stiffness degradations. In case study three, the implicit Newmark with fixed-number of iterations is applied for hybrid simulations of a 1：2 scale steel moment frame that includes a relatively complex nonlinear numerical substructure. Lastly, a more complex numerical substructure is considered by constructing a nonlinear computational model of a moment frame coupled to a hybrid model ofa 1：2 scale steel gravity frame. The last two case studies are conducted on the same porotype structure and the selection of time steps and fixed number of iterations are closely examined in pre-test simulations. The generated unbalance forces is used as an index to track the equilibrium error and predict the accuracy and stability of the simulations.

Parameters Sensitivity Characteristics of Highly Integrated Valve-Controlled Cylinder Force Control System

Nowadays, a highly integrated valve?controlled cylinder(HIVC) is applied to drive the joints of legged robots. Although the adoption of HIVC has resulted in high?performance robot control, the hydraulic force system still has problems, such as strong nonlinearity, and time?varying parameters. This makes HIVC force control very diffcult and complex. How to improve the control performance of the HIVC force control system and find the influence rule of the system parameters on the control performance is very significant. Firstly, the mathematical model of HIVC force control system is established. Then the mathematical expression for parameter sensitivity matrix is obtained by applying matrix sensitivity analysis(PSM). Then, aimed at the sinusoidal response under(three factors and three levels) working conditions, the simulation and the experiment are conducted. While the error between the simulation and experiment can’t be avoided. Therefore, combined with the range analysis, the error in the two performance indexes of sinusoidal response under the whole working condition is analyzed. Besides, the sensitivity variation pattern for each system parameter under the whole working condition is figured out. Then the two sensitivity indexes for the three system parameters, which are supply pressure, proportional gain and initial displacement of piston, are proved experimentally. The proposed method significantly reveals the sensitivity characteristics of HIVC force control system, which can make the contribution to improve the control performance.

Proportion Integration Differentiation(PID)Control Strategy of Belt Sander Based on Fuzzy Algorithm

Aiming at solving the problems of response lag and lack of precision and stability in constant grinding force control of industrial robot belts,a constant force control strategy combining fuzzy control and proportion integration differentiation(PID)was proposed by analyzing the signal transmission process and the dynamic characteristics of the grinding mechanism.The simulation results showed that compared with the classical PID control strategy,the system adjustment time was shortened by 98.7%,the overshoot was reduced by 5.1%,and the control error was 0.2%-0.5%when the system was stabilized.The optimized fuzzy control system had fast adjustment speeds,precise force control and stability.The experimental analysis of the surface morphology of the machined blade was carried out by the industrial robot abrasive grinding mechanism,and the correctness of the theoretical analysis and the effectiveness of the control strategy were verified.

A Novel Integrated Stability Control Based on Differential Braking and Active Steering for Four-axle Trucks

Di erential braking and active steering have already been integrated to overcome their shortcomings. However, existing research mainly focuses on two-axle vehicles and controllers are mostly designed to use one control method to improve the other. Moreover, many experiments are needed to improve the robustness; therefore, these control methods are underutilized. This paper proposes an integrated control system specially designed for multi-axle vehicles, in which the desired lateral force and yaw moment of vehicles are determined by the sliding mode control algorithm. The output of the sliding mode control is distributed to the suitable wheels based on the abilities and potentials of the two control methods. Moreover, in this method, fewer experiments are needed, and the robustness and simultaneity are both guaranteed. To simplify the optimization system and to improve the computation speed, seven simple optimization subsystems are designed for the determination of control outputs on each wheel. The simulation results show that the proposed controller obviously enhances the stability of multi-axle trucks. The system improves 68% of the safe velocity, and its performance is much better than both di erential braking and active steering. This research proposes an integrated control system that can simultaneously invoke di erential braking and active steering of multi-axle vehicles to fully utilize the abilities and potentials of the two control methods.

Impact of computed tomography image and contact force technology on catheter ablation for atrial fibrillation

AIM:To investigate the impact of using computed tomography(CT) and contact force(CF) technology on recurrence of atrial tachyarrhythmia after atrial fibrillation(AF) ablation.METHODS: This non-randomized study included 2 groups of patients. All patients had symptomatic recurrent paroxysmal or persistent AF and were treated with at least 1 anti arrhythmic medication or intolerant to medication. The first group included 33 patients who underwent circumferential pulmonary veins isolation(PVI) for AF during 2012 and 2013 guided by CT image integration(Cartomerge, Biosense Webster, Diamond Bar, CA, United States) of left atrium and pulmonary veins into an electroanatomic mapping(EAM) system(CT group) using standard irrigated radiofrequency catheter(Thermo Cool, Carto, Biosense Webster, Diamond Bar, CA, United States) or irrigated catheter with integrated CF sensor(Smart Touch, Carto, Biosense Webster, Diamond Bar, CA, United States). The second group included immediately preceding 32 patients who had circumferential PVI by standard irrigated catheter(Thermo Cool) using only EAM(Carto) system(EAM group). Linear lesions were performed according to the discretion of operator. RESULTS: Sex, age, and persistent AF were not different between groups. PVI was achieved in all patients in both groups. Linear ablations including cavo-tricuspid isthmus and or roof line ablation were not different between groups. Free of atrial tachyarrhythmia during follow-up of 24 mo was significantly higher among CT group compared to EAM group(81% vs 55%; respectively; P = 0.027). When 11 patients from CT group who had ablation using Smart Touch catheter were excluded, the difference between CT group and EAM became non significant(73% vs 55%; respectively; P = 0.16). Sub analysis of CT group showed that patients who had ablation using Smart Touch catheter tend to be more free of atrial tachyarrhythmia compared to patients who had ablation using standard irrigated catheter during follow-up(100% vs 73%; respectively; P = 0.07). Major complications(pericardial effusion, cerebrovascular accident/transient ischemic attack, vascular access injury requiring intervention) did not occurred in both groups.CONCLUSION:These preliminary results suggest that CT image integration and CF technology may reduce the recurrence of atrial tachyarrhythmia after catheter ablation for AF.

Feasibility study of wave-motion milling of carbon fiber reinforced plastic holes

Carbon fiber reinforced plastic(CFRP)has been applied in aeronautics,aerospace,automotive and medical industries due to its superior mechanical properties.However,due to its difficult-to-cut characteristic,various damages in twist drilling and chip removal clog in core drilling could happen,inevitably reducing hole quality and hole-manufacturing efficiency.This paper proposes the wave-motion milling(WMM)method for CFRP hole-manufacturing to improve hole quality.This paper presents a motion path model based on the kinematics of the WMM method.The wave-motion cutting mode in WMM was analyzed first.Then,comparison experiments on WMM and conventional helical milling(CHM)of CFRP were carried out under dry conditions.The results showed that the hole surface quality of the CFRP significantly improved with a decrease of 18.1%–36%of Ra value in WMM compared to CHM.WMM exerted a significantly weaker thrust force than that of CHM with a reduction of 12.0%–24.9%and 3%–7.7%for different axial feed per tooth and tangential feed per tooth,respectively.Meanwhile,the hole exit damages significantly decreased in WMM.The average tear length at the hole exit in WMM was reduced by 3.5%–29.5%and 35.5%–44.7%at different axial feed per tooth and tangential feed per tooth,respectively.Moreover,WMM significantly alleviated tool wear.The experimental results suggest that WMM is an effective and promising strategy for CFRP hole-manufacturing.

Milling Machinability of TiC Particle and TiB Whisker Hybrid Reinforced Titanium Matrix Composites

The milling machinabilities of titanium matrix composites were comprehensively evaluated to provide a theoretical basis for cutting parameter determination. Polycrystalline diamond （PCD） tools with different grain sizes and geometries, and carbide tools with and without coatings were used in the experiments. Milling forces, milling temperatures, tool lifetimes, tool wear, and machined surface integrities were investigated. The PCD tool required a primary cutting force 15 % smaller than that of the carbide tool, while the uncoated carbide tool required a primary cutting force 10% higher than that of the TiA1N-eoated tool. A cutting force of 300 N per millimeter of the cutting edge （300 N/mm） was measured. This caused excessive tool chipping. The cutting temperature of the PCD tool was 20%-30% lower than that of the carbide tool, while that of the TiA1N-coated tool was 12% lower than that of the uncoated carbide tool. The cutting temperatures produced when using water-based cooling and minimal quantity lubrication （MQL） were reduced by 100 ~C and 200 ~C, compared with those recorded with dry cutting, respectively. In general, the PCD tool lifetimes were 2--3 times longer than the carbide tool lifetimes. The roughness Ra of the machined surface was less than 0.6μm, and the depth of the machined surface hardened layer was in the range of 0.15-0.25 mm for all of the PCD tools before a flank wear land of 0.2 mm was reached. The PCD tool with a 0.8 mm tool nose radius, 0% rake angle, 10% flank angle, and grain size of （30＋2） μm exhibited the best cutting performance. For this specific tool, a lifetime of 16 rain can be expected.

Numerical investigation on damping coefficient of the integral squeeze film damper

The elimination of rotor vibration is usually achieved by applying additional damping to the system.Squeeze film dampers are widely used in various aerospace and turbine equipments.The research is carried out on flow characteristics in the integral squeeze film dampers(ISFDs).The dynamic response to the operation condition is investigated through the computational fluid dynamics(CFD) model of ISFD.Due to the large pressure loss at the oil inlet,the oil film force only changes slightly with the increase of oil supply pressure,and the damping increases slightly.The vibration amplitude only affects the film force,but has no effect on the damping.The oil film force and damping show an upward tendency with the decrease of thickness of the end seal clearance.

Dynamics of mechanical system for electromechanical integrated toroidal drive under electric disturbance

Based on electromagnetics and mechanics, electromechanical coupled dynamic equations for the drive were developed. Using method of perturbation, free vibrations of the mechanical system under electric disturbance were investigated. The forced responses of the mechanical system to mechanical excitation under electric disturbance were also presented. It is known that for the system with electric disturbance, as time grows, beat occurs. When electric disturbing frequency is near to the natural frequencies of the mechanical system or their integer multiple, resonance vibrations occur. The forced responses of the mechanical system to mechanical excitation under electric disturbance are compound vibrations decided by mechanical excitation, electric disturbance and parameters of the system. The coupled resonance vibration caused by electric disturbance and mechanical excitation was discussed as well. The conditions under which above coupled resonance occurs were presented. The results show that when the difference of the excitation frequency and the perturbation frequency is equal to some order of natural frequency, coupled resonance vibrations occur.

Solution of a Green's function for a saturated porous medium in a half-space subjected to a torsional force

Based on the solutions of the Green＇s function for a saturated porous medium obtained by the authors, and using transformation of axisymmetric coordinates, Sommerfeld integrals and superposition of the influence field on a free surface, the authors have obtained displacement solutions of a saturated porous medium subjected to a torsional force in a half-space. The relationship curves of the displacement solutions and various parameters （permeability, frequency, etc.） under action of a unit of torque are also given in this paper. The results are consistent with previous Reissner＇s solutions, where a two-phase medium decays to a single-phase medium. The solution is useful in solving relevant dynamic problems of a two- phase saturated medium in engineering.

Numerical solutions of singular integral equations for planar rectangular interfacial crack in three dimensional bimaterials

Stress intensity factors for a three dimensional rectangular interfacial crack were considered using the body force method. In the numerical calculations, unknown body force densities were approximated by the products of the fundamental densities and power series; here the fundamental densities are chosen to express singular stress fields due to an interface crack exactly. The calculation shows that the numerical results are satisfied. The stress intensity factors for a rectangular interface crack were indicated accurately with the varying aspect ratio, and bimaterial parameter.

Maxwell-Chern-Simons Casimir Force Between Perfectly Conducting Parallel Lines

Using Feynman path integral method we calculate the Casimir force of Maxwell Chern Simons Abelian gauge field between perfectly conducting parallel lines.

新质生产力促进我国体育产业高质量发展的关联机理、内在逻辑与实施方略

新质生产力是推进我国经济社会高质量发展的强劲动力。从历史视野审视发现,中国式现代化进程中我国体育产业迫切需要引入新的增长动力来实现高质量发展。研究认为,新质生产力可以重塑体育产业增长的底层逻辑、促进体育产业整合与产业重构、拓展体育产业高质量发展的虚拟空间;新质生产力通过为体育产业发展提供新质和新型生产要素、打造创新驱动和协同发展模式、倒逼体育管理体制机制改革创新促进体育产业高质量发展;同时,产业性原创性关键技术研发能力不足、数字体育基础设施及信息资源匮乏、体育产业创新文化和创新氛围亟待培育等制约新质生产力作用的发挥;培育和发展体育产业领域新质生产助力体育产业高质量发展,应推进问题导向的体育科技攻关,加强数字体育基础设施建设,夯实体育产业发展的文化基础,积极推进技术创新与价值回归,增强有为政府和有效市场的更好结合。

高校服务新质生产力发展的能力审视与评价机制改革

新质生产力以科技创新为驱动,以高层次创新型人才为支撑,以战略性新兴产业和未来产业为载体,是高效能、高质量的新质态生产力。新质生产力的持续发展要求高校为之提供新质性的人才和科技支持,但长期以来基于效率取向的高校评价模式束缚了高校的生产力和服务力。深化高校评价机制改革,构建质量取向的新评价体系,是高校解放生产力,有效参与和服务新质生产力发展的必要举措。构建新的评价体系,当务之急是塑立基于“质量与贡献”的评价标准,改革政府主导的行政性评价,促进高校评价的生态化,强化高校自我评价的发展价值。

外圆磨削18CrNiMo7-6力模型及表面完整性研究

为了准确和有效地控制磨削参数对磨削力及表面完整性的影响,通过解析法,以磨粒与材料间的塑性变形、压痕理论以及剪切应变效应为理论依据,建立了三阶段的磨削力理论模型。选定棕刚玉砂轮进行磨削试验,探究了磨削参数对磨削力的影响以及磨削参数和磨削力对表面完整性的影响,通过外圆横向磨削正交试验获得了外圆磨削最优工艺参数。结果表明,外圆磨削力模型法向磨削力和切向磨削力的预测平均误差分别为5.56%和7.08%;砂轮径向进给速度f_(r)对磨削力的影响最大,磨削宽度b次之,工件转速n_(w)和砂轮粒度的影响较小;f_(r)和b对残余应力的影响较大,砂轮粒度对表面粗糙度的影响最大;随着磨削力的增大,表面粗糙度值一直增大,残余应力先减小后增大,沿深度方向残余应力最大值先增大后减小,在试验所取参数条件下,影响残余应力的深度分布范围基本在20~40μm;最优工艺参数组合如下:f_(r)=0.15 mm/min,n_(w)=120 r/min,b=10 mm,砂轮粒度80。

Development of an Integrated Coastal Vulnerability Index for the Ivorian Coast in West Africa

This study assesses the vulnerable state of the 566-km Ivorian coastal area using the physical (geomorphology, coastal slope, coastal retreat rate, relative sea level rise and wave/Tide energy) and socio-economic (coastal population density, harbor, airport, road, land use and protected area) factors as indicators. This enabled an Integrated Coastal Vulnerability Index to be determined for the Ivorian coastal zone. This Index could be defined as the weighted average of indexes based on physical and socio-economic factors. The study revealed that vulnerability of the western and the eastern coastlines of Cote d’Ivoire are strongly influenced by human activities, while physical forcing affects significantly the vulnerability of the central section. The relative vulnerability of the different sections depends also strongly on the geomorphology, wave energy, coastal population density and land use factors. The west and central sections of the coastline are more resilient than the eastern section when integrating physical and socio-economic factors. The Integrated Coastal Vulnerability Index, based on physical and socio-economic factors, appears to be more appropriate for coastal vulnerability assessment. These results could be useful in the development of adaptation strategies to increase the resilience of this coastal area and then extended for West Africa Coastal Areas Management.

科教融汇赋能新质生产力:内在逻辑、现实困境和实践路径——基于高等职业教育的视角

在新质生产力背景下,科教融汇成为推动社会经济发展和提高劳动者竞争力的重要途径。通过对科教融汇的历史进程、新质生产力的特征分析,从理论逻辑、社会逻辑和技术逻辑三个层面阐述了科教融汇赋能新质生产力的内在逻辑。科教融汇本质上是通过合理的科教资源配置,不断提高创新人才培养质量,但面临治理环境缺乏支撑、科教赋能建设不足、创新融合深度缺乏等现实困境。因此,可从实践出发,从以下方面探索科教融汇赋能新质生产力的实践路径:统筹谋划顶层设计,形塑科教文化生态;多元主体积极参与,完善政策支持体系;增强人才培养供需耦合,提供高素质劳动者队伍;完善科研创新平台建设,创新数字技术运用场景。

加快发展新质生产力的主要措施与产业政策转型

发展以智能技术为代表的新质生产力,在时间分布上要动态合理地配置传统产业改造、新兴产业壮大、未来产业培育三大任务,尤其要高度重视用智能化新技术对传统产业进行改造升级;在具体策略上要积极推进针对现有产业的“智改数转网联”三大行动,尤其要注重“网联”行动;在治理结构上要大力培育“链主”企业、“专精特新”企业、中小企业三类主体,尤其要聚焦上下游互动与市场化治理,以突破各种创新的瓶颈;在动力机制上要努力增强创新、改革、开放三大引擎的动能,尤其要加大对内开放的力度;在要素结构上要充分展现知识、技术、人才三大要素的市场价值,畅通教育、科技、人才的良性循环。同时,不仅要在理论上澄清一些认识误区,也要对现有产业政策的实施方式进行改革,如从注重产能扩张转向创新支持、从地方主导型转向中央主导型、从挑选“输家赢家”转向创造竞争环境、从补贴生产者转向补贴用户,以防止在实践中出现产能严重过剩等泡沫化现象与问题,最大限度地支持新质生产力发展。