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A computational aero-acoustic (CAA) method is used to predict the tonal noise generated from a cavity of automobile door seals or gaps at low flow Mach numbers (M=0.077 and 0.147). In the present method, the acoustically perturbed Euler equations are solved with the acoustic source term obtained from the unsteady incompressible Navier-Stokes calculations of the cavity flow in self-sustained oscillations. The aerodynamic and acoustic fields are computed for the Reynolds numbers based on the displacement thickness, Reδ*=850 and 1620 and their fundamental mode characteristics are investigated. The present method is also verified with the experimentally measured sound pressure level (SPL) spectra.  相似文献
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The proportional pressure control valve having versatile functions and higher performance is an essential component in the open loop controlled rear wheel steering gear of the four wheel steering system on a passenger car. In this study, the authors suggest a new type of load pressure feedback mechanism which can make it easy to change the control range of load pressure without changing the capacity of solenoid. The concept of the suggested mechanism, composed of the pressure chamber with throttles in series, was described. The mathematical model was derived from the rear wheel steering gear system consisting of a valve and a cylinder for the purpose of analyzing the valve characteristics. And the programme for computing the characteristic of the valve was developed. Experiments were carried out to confirm the performance of the valve and computations were performed to ascertain the usefulness of the developed programme. The results from the computations fairly coincide with those from the experiments. The results from the experiments and computations show that the performance of new valve is as good as that of the already developed one and the new valve has an advantage in the easiness in varying the control range of load pressure.  相似文献
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由于实验室条件限制,发射装置在随主机进行综合航电系统试验时没有液压系统。为了满足实验室联试试验时的需要,使用凌华公司的数据采集卡DAQ-2501多功能卡搭建出系统的硬件平台,软件方面在VC++环境下,利用多线程技术设计实现了基于PCI的多通道高速数据采集与反馈系统,用于模拟发射装置的机构动作。详细介绍整个系统的设计思路,对其中使用到的关键技术进行了研究,实验证明,系统具有较高的可靠性。  相似文献
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针对机械产品装配过程中的实时物料配送问题,在分析实时物料配送过程的优化目标、影响因素以及约束条件的基础上,重点研究了一种与制造执行系统结合的实时物料配送方法。通过生成物料配送计划、对物料进行跟踪管理以及实时反馈机制的运用,实现了装配车间物料的实时、小批量配送,并通过实例验证了上述方法的有效性和可行性。  相似文献
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For MIMO mechanical systems using position measurements only, this paper presents a dynamic output feedback sliding mode control algorithm in which an additional dynamics is introduced into the design of the sliding surface. Although the system has the mismatched uncertainty and external disturbance, once the system is in the sliding mode, the proposed method can guarantee robust stabilization and sustain the nature of performing disturbance attenuation through utilizing H control analytical technique. A controller is then designed to drive the system to the sliding surface in a finite time and stay on it thereafter. Finally, a numerical example is explained for demonstrating the applicability of the proposed scheme.  相似文献
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依据现代设计心理学,利用四杆机构、楔形滑块及摩擦块组成的速度反馈机构自动控制速度,以及分步逐级减速的方法设计了操作简易快捷的高楼逃生装置,它具有逃生速度可实现自动调节并稳定在可控范围、在不需要其它能源下能照明和发出求救信号、对称结构可以像蠕虫一样交互式下降、可实现多人次循环逃生等特点。  相似文献
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