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Numerical Study of the Vibrations of Beams with Variable Stiffness under Impulsive or Harmonic Loading

World Journal of Engineering and Technology 2024年第2期12卷 401-425页

作者： moussa sali Fabien Kenmogne Jean Bertin Nkibeu Abdou Njifenjou Laboratory of Materials Mechanics and Civil Engineering National Higher Polytechnic School of Maroua University of Maroua Maroua Cameroon Department of Civil Engineering Advanced Teachers Training College of the Technical Education University of Douala Douala Cameroon Laboratory Engineering Civil and Mechanics National Advanced School of Engineering University of Yaound&#233 1 Yaound&#233 Cameroon Laboratory of Energy Materials Modeling and Method (E3M) National Advanced School of Engineering University of Douala Douala Cameroon Laboratory of Mathematical Engineering and Information Systems National Advanced School of Engineering University of Yaound&#233 1 Yaound&#233 Cameroon

The behavior of beams with variable stiffness subjected to the action of variable loadings (impulse or harmonic) is analyzed in this paper using the successive approximation method. This successive approximation method is a technique for numerical integration of partial differential equations involving both the space and time, with well-known initial conditions on time and boundary conditions on the space. This technique, although having been applied to beams with constant stiffness, is new for the case of beams with variable stiffness, and it aims to use a quadratic parabola (in time) to approximate the solutions of the differential equations of dynamics. The spatial part is studied using the successive approximation method of the partial differential equations obtained, in order to transform them into a system of time-dependent ordinary differential equations. Thus, the integration algorithm using this technique is established and applied to examples of beams with variable stiffness, under variable loading, and with the different cases of supports chosen in the literature. We have thus calculated the cases of beams with constant or variable rigidity with articulated or embedded supports, subjected to the action of an instantaneous impulse and harmonic loads distributed over its entire length. In order to justify the robustness of the successive approximation method considered in this work, an example of an articulated beam with constant stiffness subjected to a distributed harmonic load was calculated analytically, and the results obtained compared to those found numerically for various steps (spatial h and temporal τ ¯ ) of calculus, and the difference between the values obtained by the two methods was small. For example for ( h=1/8 , τ ¯ =1/ 64 ), the difference between these values is 17%.

关键词： Successive Approximations Method Direct Integration Differential Equations Beams of Variable Stiffness Quadratic Parabola Impulse and Harmonic Loads

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Optimization and Simulation of the Process of Scenario-driven V2X Applications Testing

Optimization and Simulation of the Process of Scenario-drive...

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作者： moussa sali 长安大学

学位级别：硕士

智能车路系统(Intelligent Vehicle-Infrastructure System,IVIS)是交通领域的前沿科技,是以车和路的智能化为条件,强调车与路智能协同能力和服务水平的复杂系统;是引发道路交通组织和运行形态变革,解决道路交通安全、拥堵、污染等重大... 详细信息

智能车路系统(Intelligent Vehicle-Infrastructure System,IVIS)是交通领域的前沿科技,是以车和路的智能化为条件,强调车与路智能协同能力和服务水平的复杂系统;是引发道路交通组织和运行形态变革,解决道路交通安全、拥堵、污染等重大问题的有效手段。车道保持、自适应巡航控制、行人/障碍物避免碰撞、自动变道、紧急制动系统等驾驶员辅助系统正在高端汽车中应用。车-车(V2V)和车-路(V2I)通信是V2X技术在行车安全方面的两个主要应用,可以为司机提供超视距的道路危险和环境信息。这些应用有助于提升交通运输的安全和效率,减少事故发生的可能性,降低事故的损失。然而,配备V2X应用的车辆必须经过充分的评估与测试,以确保它们的功能与性能达到相应道路准入要求。本论文针对场景驱动的V2X应用测试过程的优化问题开展研究,通过最小化评估时间和最大化对给定测试场可用资源实现V2X应用测试过程的优化。本文的主要研究工作包括:1)单位距离测试场景数最大化算法(Maximization of Scenarios per Mile for a Given Test Field,MSM-GTF)。该算法在给定测试场、测试入口位置和出口位置条件下,在Dijkstra算法的基础上对松弛函数进行修改,实现单位距离测试场景数最大化的最优路径搜索。该路径可以最大限度地利用可用资源,并优化V2X测试过程所需的总体评估时间。2)给定测试规范的最优路径搜索(Optimal Route Search for a Given Test Case Scenarios,ORS-GTCS)算法。ORS-GTCS算法将给定测试规范的最优路径搜索问题建模为混合整数线性规划的最优路径问题。该算法在给定测试场、一组测试场景规范、测试入口位置和出口位置的条件下,实现满足测试场景规范的最优路径规划,从而优化V2X测试过程所需的总体评估时间。3)微观交通模拟器SUMO中场景注入与仿真。为了进一步验证论文提出的ORS-GTCS算法,论文使用公安部交通管理科学研究所的真实测试场的路网结构,应用ORSGTCS算法得到的最优路径作为SUMO仿真的输入,通过注入测试场景方法对优化的V2X测试过程进行了仿真与验证。

关键词： Test scenarios V2X applications Test and simulation constrained shortest path SUMO path planning

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A Review on Methods for Determining the Vibratory Damping Ratio

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Open Journal of Civil Engineering 2023年第2期13卷 199-209页

作者： Nkibeu Jean Bertin Charly Julien Nyobe moussa sali Madja Doumbaye Jerémie Laboratory Engineering Civil and Mechanics National Advanced School of Engineering The University of Yaoundé 1 Yaounde Cameroon Mechanics Laboratory Advanced Technical Teachers Training College The University of Douala Douala Cameroon Department of Civil Engineering Advanced Technical Teachers Training College The University of Douala Douala Cameroon Department of Civil Engineering National Advanced School of Public Works Yaounde Cameroon

This article aims to popularize the methods for determining the vibratory damping ratio, to explain the various mathematical and physical theorems related to the establishment of literal expressions. Vibration damping is an essential parameter to reduce the dynamic responses of structures. The study aimed at its determination is necessary and essential for the safeguard of buildings and human lives during the earthquake. Among the main methods studied in this article, the free vibration attenuation method seems to be easy to implement but requires a state-of-the-art device to capture the responses. In addition to this device, the other methods require other equipment for the vibration of the system and the transformation of the responses in the frequency domain.

关键词： Damping Oscillator Attenuation of Free Vibrations Amplification at Resonance Resonance Peak Width Energy Dissipated by Damping Stored Elastic Energy

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Research on the Comparison between the Different Policies by Service Level and Inventory Level Performance of Auto Parts in N.A.C.C.(North Automobile Components Company)

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Journal of Management Science & Engineering Research 2022年第2期5卷 1-16页

作者： Sory Ibrahima Cisse Jianwu Xue moussa sali School of Management Northwestern Polytechnical UniversityXi’an710072China School of Information Engineering Chang’an UniversityXi’anChina

As after sales services become more and more popular,particularly preventive or corrective maintenance,the intervention and repair of the customer’s goods in a timely and efficient manner ensure customer satisfaction and contribute to the establishment of brand image in the market of the *** availability and quality of spare parts are key elements of this strategy while ensuring minimal management *** reuse of spare parts retrieved from customer systems is a growing maintenance strategy practice which impacts the traditional spare parts supply *** reuse is primarily driven by extending the economic life of goods,initially regarded as waste and therefore without added value,by transforming them into valuable spare parts that can be reused;secondly,for environmental or regulatory reasons,demanding responsibility for the treatment of products at the end of their life;and thirdly,to improve the availability of parts for maintenance,especially parts that the organization can no longer purchase or that are impacted by other *** also involves the analysis of their condition and their eventual return to working order as they are retrieved from the customer’s systems in a defective *** this paper,we will identify and classify the different customers and spare parts by estimating the critical level of rationing policy based on forecasts,identify the thresholds of inventory management policies,and finally,compare the different policies by service level and inventory level performance for the ***.

关键词： Classification Policies Auto parts Forecast Performance analysis Comparison

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