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Testing of electronic systems using conventional testing methods has become more difficult and costly as these systems have become more complex and compact. Conventional testing methods and systems often require lengthy analysis to define testing strategies. These test systems may require lengthy test periods, complex stimulus and measurement instrumentation as well as complicated fixturing. The results are often ambiguous and require further interpretation. This paper presents an exploration of a “non-intrusive” test method based on interpreting changes in the magnetic field close to a Printed Circuit Board (PCB). Currents moving between devices on the PCB produce these magnetic fields. Changes of the PCB operational status due to faults cause changes in the associated magnetic field pattern that can be interpreted by Artificial Neural Networks (ANNs) for fault identification. An apparatus to collect magnetic field measurements is described along with some problems of collecting data. Typical magnetic field patterns for “known-good” and faulted PCBs are presented. Possible extensions of the method are discussed. This paper resulted from internally funded work at Southwest Research Institute (SwRI) concerning non-intrusive diagnostic techniques 相似文献
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Keenan E. Wright R.G. Zgol M. Mulligan R. Tagliava V. Kirkland L.V. 《Aerospace and Electronic Systems Magazine, IEEE》2004,19(6):9-15
This paper describes research and development efforts in the use of infrared (IR) laser beams for detecting failures in integrated circuits resident on printed circuit boards. This work involves taking advantage of the transparency of the silicon substrate of ICs to radiation in the near infrared (NIR) spectrum to devise a non-invasive method for imaging the component circuitry of the IC. The implication is that a means to see into the physical structure of an integrated circuit can be created by using lasers tuned to these wavelengths. While the silicon substrate is transparent to the laser, the circuit paths and devices embedded within the substrate are readily visible since their metallic composition is opaque to laser energy at this wavelength. A laser test fixture consisting of a 1064 nm continuous wave laser, CCD camera, and image acquisition board is used to generate images from flip-chip integrated circuits. Multiresolution image processing techniques are then applied to the resulting images to identify potential defects. 相似文献
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印刷电路板的动力学特性直接影响机载电子设备在振动和冲击环境下的工作可靠性,有必要在设计阶段对其进行动力学分析.印刷电路板为薄壁结构,质量一般较小,在使用传统的加速度传感器测量时,传感器的附加质量会对模态测试结果造成影响.通过加速度传感器与激光测振仪测试数据的对比,分析了加速度传感器附加质量对模态测试结果的影响,验证了传感器附加质量消除方法的效果,结论认为传感器附加质量对印刷电路板模态测试的结果影响明显且这种影响不能被完全消除;使用扫描式激光测振仪可以得到精确详细的模态参数. 相似文献
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针对类客车体(Ahmed Model)1:1.5模型,采用风洞试验和数值模拟相结合的研究方法,研究了在模型尾部安装多种构型的隔板对气动阻力特性的影响规律。通过分析各种构型隔板对尾流结构和尾部压力分布的影响,初步分析了尾部隔板的减阻机理。研究结果表明:①隔板须根据尾涡结构设计其参数和构型布置,才能达到较理想的减阻效果;②隔板以适当的参数及构型布置时,可以控制尾涡、提高尾部压力、减小压差阻力;③针对该文模型,当隔板宽度为60mm,距尾部后缘10mm,并以3横3纵构型布置时,模型阻力系数降低达15.58%。 相似文献
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去年下半年以来,世界航空运输业因全球金融危机影响开始步入衰退,为了应对危机,国际航空巨头纷纷祭起联合重组的法宝,先后有美国达美航空公司与美国西北航空公司、英国航空公司和西班牙伊比利亚航空公司重组的消息传出。在国内,民航新一轮联合重组的呼声频现报端。在人们更多关注联合重组对市场影响之时,我们不应忽视对联合重组法律关系的研究, 相似文献
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Cooperation between the Eveready Battery Company and the Environmental Protection Agency has already led to significant improvements for the environment. Eveready Battery Company, Inc. and the Environmental Protection Agency (EPA) have for many years worked successfully in partnership for the benefit of the environment. This article examines an example of successful cooperation and partnership between Eveready and the EPA. In the early 1980's, the environmental community began to focus its attention on the mercury in household batteries. Studies had been performed in the US, Japan and the United Kingdom regarding the potential environmental harm resulting from the disposal of household batteries containing mercury 相似文献
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Proceeding from the first assumption of kinetic-molecular theory, the authors propose the Toms effect on reducing the hydrodynamic drag in a turbulent flow with polymer additives and its usage in power plants, to be explained. 相似文献
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耿宏 《中国民航学院学报》1999,17(4):31-37
以三菱AnS系列可编程控制器为例,在介绍其主要模块的性能参数基础上,从硬件和软件两方面,阐述了如何实现对拦焦机和装煤车的控制及其控制特点。 相似文献
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Previous test sequencing algorithms only consider the execution cost of a test at the application stage. Due to the fact that the placement cost of some tests at the design stage is considerably high compared with the execution cost, the sequential diagnosis strategy obtained by previous methods is actually not optimal from the view of life cycle. In this paper, the test sequencing problem based on life cycle cost is presented. It is formulated as an optimization problem, which is non-deterministic polynomial-time hard (NP-hard). An algorithm and a strategy to improve its computational efficiency are proposed. The formulation and algorithms are tested on various simulated systems and comparisons are made with the extant test sequencing methods. Application on a pump rotational speed control (PRSC) system of a spacecraft is studied in detail. Both the simulation results and the real-world case application results suggest that the solution proposed in this paper can significantly reduce the life cycle cost of a sequential fault diagnosis strategy. 相似文献
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传统的薪酬管理普遍关注的是薪酬的基本制度设计和相关技术方法。在航空业迅速发展的今天,市场竞争持续加剧,民航系统各单位员工的工作性质和工作动机日益复杂,作为发挥重要激励和约束功能的薪酬管理体系已不能停留在简单的操作、技术和制度层面,它作为一种能有效辅助民航强国战略实施的重要人力资源管理手段,应该逐步纳 相似文献
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近年来,国内航空企业广泛开展了企业文化建设。但是,经过较长时间的实践后发现,文化建设在航空企业经营管理中所发挥的作用与预期还有所差距。其原因主要在于企业文化与经营管理脱节,存在着两条腿走路、各行其事的现象,严重的甚至互相矛盾和冲突。因此,现阶段如何提高航空企业文化执行力,让优秀的企业文化真正为安全生产和经营管理服务,是我们必须认真思考的问题。 相似文献
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<正>先让我们看一则新闻:麦当劳近年来将主要的市场转向年轻人群体。在2009夏季促销调查中麦当劳发现,年轻人尤其是大学生目前的主要业余时间都用在了网络交流上,而人人网 相似文献
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在一座小型跨超声速风洞上采用夏克-哈特曼波前传感器进行了Ma=3试验段流场对光传输特性影响的试验研究。空风洞流场的测试结果表明,由于试验段壁面湍流边界层中气流脉动与流场密度变化的影响,光波前会发生畸变。为了降低湍流边界层流场对光传输的影响,在风洞试验段单侧壁板上安装导流板进行了试验。测试数据表明,光波前畸变量的PV均值和RMS均值分别由3.5λ和0.73λ降低到了1.09λ和0.22λ,而且光波前畸变量的波动幅度也大为降低。初步研究结果说明,采用加装导流板等措施可以显著降低风洞流场对光传输的影响,有利于提高风洞试验时流场显示与测量结果的可靠性和有效性。 相似文献
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