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141.
A solution method suitable for the multi-threaded simulation ofmechanical systems represented in Cartesian coordinates isproposed and analyzed. In a state-space framework for thesolution of the Differential Algebraic Equations (DAE) ofMultibody Dynamics, the position/velocity stabilization and theacceleration computation are based on iterative solvers applied toequivalent reduced problems. The most in-depth computationalaspect analyzed is the preconditioning, i.e., the direct solutionof the reduced systems. Provided a topology index reduction is first applied to the model, the effort for the direct solution of the reduced systems is shown to be of order O(N
J
), where N
J
is the number of joints in the model. The recurring theme of thepaper is the central role that the topology of the mechanicalsystem plays in the overall performance of the numericalsimulation. Based on the topology of the model, parallelcomputational threads can be established to start in the equationformulation and continue through the iterative numericalalgorithms employed for the numerical solution. Task schedulingthese parallel threads is expected to redeem real-time performancefor certain classes of complex applications. 相似文献
142.
钢铁企业的氧气厂要深入了解本企业的用氧情况及周边市场的需要,据此确定拟新增空分装置的设计参数,选定最适宜的空分流程。探讨了空分流程选择时要考虑的几个方面。介绍了一种对空分装置的投资和长期运行费用之间进行经济性分析的定量计算公式,并得出了四点结论。 相似文献
143.
144.
Michael Fox Richard Hastings Scott Lovald Juan Heinrich 《Journal of Failure Analysis and Prevention》2007,7(3):165-174
A failure analysis case study is presented for a two-piece aerosol containing tetrafluoroethane, commonly referred to as Refrigerant
134a. A gentleman was preparing to recharge the air conditioning system of an automobile when the bottom exploded off the
aerosol container, propelling the body of the aerosol container like a rocket, which hit the man in the eye and blinded him
in that eye. The aerosol was never connected to the air conditioner, therefore backpressure from the air conditioner (AC)
compressor was ruled out as a cause for the explosion. The objective of the study was to determine why the aerosol exploded.
Several recently developed test methods were used, including two types of heat-to-burst tests and a puncture chamber to measure
the pressure-versus-temperature behavior of aerosols. More common test methods were also used, such as water bath pressure
tests, hydro pressure burst tests, pneumatic pressure burst tests, hardness measurements, weight measurements, metallography,
scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and an accident scenario recreation. A semi-empirical
correlation between the hardness and weights of the container bottoms was used to determine the explosion temperature and/or
pressure. This semi-empirical correlation agrees in principle with an analysis of the explosion pressures using finite-element
analysis (FEA). The root cause for the explosion was determined to be a lack of strength of the bottom of the two-piece aerosol
coupled with heating the aerosol to temperatures significantly above room temperature. 相似文献
145.
基于物元分析和层次分析的选厂综合性能评估 总被引:3,自引:2,他引:1
利用物元分析法和层次分析法的特点,将物元分析和层次分析法有机的结合起来建立选厂性能综合评估模型,建立的评估模型表明该评估方法能够克服传统方法中参评人员的主观不确定性和认识上的模糊性,可用于选厂有关指标的综合评估。 相似文献
146.
147.
This paper presents an application of digital signal processing to data acquired by the radio imaging method (RIM) that was adopted to measure moisture distribution inside the human body. RIM was originally developed for the mining industry; we are applying the method to a biomedical measurement because of its simplicity, economy, and safety. When a two‐dimensional image was constructed from the measured data, the method provided insufficient resolution because the wavelength of the measurement medium, a weak electromagnetic wave in a VHF band, was longer than human tissues. We built and measured a phantom, a model simulating the human body, consisting of two water tanks representing large internal organs. A digital equalizer was applied to the measured values as a weight function, and images were reconstructed that corresponded to the original shape of the two water tanks. As a result, a two‐dimensional image containing two individual peaks corresponding to the original two small water tanks was constructed. The result suggests the method was applicable to biomedical measurement by the assistance of digital signal processing. This technique may be applicable to home‐based medical care and other situations in which safety, simplicity, and economy are important. 相似文献
148.
从理论上分析了产生地电流干扰的原因,从而在实践上提出了一些经常被忽略,却是行之有效的方法来减小地电流的干扰,设计出高质量的电路。 相似文献
149.
150.
对氨基二苯胺是性能优异的对苯二胺类防老剂的中间体。其质量好坏直接关系到防老剂4020、4010NA、688等品种的质量。对氨基二苯胺质量检验方法的提出则有助于我们开拓思路,更新质量观念,地症下药,分析原因,采取措施,全面提高其内在质量。 相似文献