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991.
Valia T. Petkova Lu Yuan Roxana A. Ion Peter C. Sander 《Reliability Engineering & System Safety》2005,88(2):147
It is well-known [Reliab. Eng. Syst. Saf. 75 (2002) 295] that in modern development processes it is essential to have an information flow structure that facilitates fast feedback from product users (customers) to departments at the front end, in particular development and production. As information is only relevant if it is used when taking decisions, this paper presents a guideline for building field feedback information flows that facilitate the decision taking during the product creation and realisation process. The guideline takes into consideration that the type of decisions depends on the span-of-control, therefore following Parsons [Structure and Process in Modern Societies (1990)] the span-of-control is subdivided into the following three levels: strategic, tactic, and executive. The guideline is illustrated with a case in which it is used for analysing the quality of existing field feedback flows. 相似文献
992.
High quality Tl2Ba2CaCu2O8 (Tl-2212) superconducting thin films are prepared on both sides of 2 in. LaAlO3(0 0 1) substrates by off-axis magnetron sputtering and post-annealing process. XRD measurements show that these films possess pure Tl-2212 phase with C-axis perpendicular to the substrate surface. The thickness unhomogeneity of the whole film on the 2 in. wafer is less than 5%. The superconducting transition temperatures Tcs of the films are around 105 K. At zero applied magnetic field, the critical current densities Jcs of the films on both sides of the wafer were measured to be above 2 × 106 A/cm2 at 77 K. The microwave surface resistance Rs of film was as low as 350 μΩ at 10 GHz and 77 K. In order to test the suitability of Tl-2212 thin films for passive microwave devices, 3-pole bandpass filters have been fabricated from double-sided Tl-2212 films on LaAlO3 substrates. 相似文献
993.
Solder joint fatigue failure is a serious reliability concern in area array technologies, such as flip chip and ball grid array packages of integrated-circuit chips. The selection of different substrate materials could affect solder joint thermal fatigue life significantly. The reliability of solder joints in real flip chip assembly with both rigid and compliant substrates was evaluated by the accelerated temperature cycling test and thermal mechanical analysis. The mechanism of substrate flexibility on improving solder joint thermal fatigue lifetime was investigated by fracture mechanics methods. Two different methods (crack tip opening displacement, CTOD and virtual crack closure technique, VCCT) are used to determine the crack tip parameters which are considered as the indices of reliability of solder joints, including the strain energy release rate and phase angle for the different crack lengths and temperatures. It was found that the thermal fatigue lifetime of solder joints in flip chip on flex assembly (FCOF) was much longer than that of flip chip on rigid board assembly (FCOB). The flex substrates could dissipate energy that otherwise would be absorbed by solder joints, that is, substrate flexibility has a great effect on solder joint reliability and the reliability improvement was attributed to flex buckling or bending during thermal cycling. 相似文献
994.
Ahmad E. Valavanis A. Claydon J.S. Lu Y.X. Xu Y.B. 《IEEE transactions on magnetics》2005,41(10):2592-2594
We report experimental transport measurements of a vertical hybrid ferromagnetic (FM)/III-V semiconductor (SC)/ferromagnetic(FM) type structure, i.e., Cr(20ML)/Co(15ML)/GaAs(50 nm, n-type)/Al/sub 0.3/Ga/sub 0.7/As(200 nm, n-type)/FeNi(30 nm). The current-voltage (I-V) characteristics reveal Schottky/tunneling type behavior in the direction of FeNi/Semiconductor/Co and observed to be dependent on external magnetic field. The magnetoresistance (MR) behavior shows a strong dependence on the measured current and field. At low fields no significant change in MR has been observed with increasing current. However, at high fields the MR initially increases with increasing current and becomes stable beyond a critical current of 10 /spl mu/A. A maximum of 12% change in the MR has been observed at room temperature, which is far larger than that of the conventional AMR effect. This property of the device could be utilized as field sensors or magnetic logic devices. 相似文献
995.
996.
介绍一种基于S698处理器的嵌入式系统教学平台,平台针对嵌入式系统开放式、设计型教学的特点进行设计;详细描述教学平台的硬件系统设计和软件实现。该教学平台具有易学习,简洁美观,方便实用等特点。 相似文献
997.
998.
根据铝型材氧化着色电泳自动生产线的布局结构及其PLC控制网络系统的特点,应用组态软件RSView32及嵌入式VBA开发该生产线的自动监控系统。介绍了监控工作站与PLC站点的数据通信接口及实现方法。应用基于事件驱动的动态调度方法实现行车的动态调度与决策,并给出了主要程序模块的工作流程图。 相似文献
999.
The transfer of mass flow between ironmaking and steelmaking process at Baoshan Iron and Steel Co. Ltd. has been analyzed. The mathematic-physical models of transport scheduling for hot metal manufacturing have been researched combined with the practical problem in the metallurgical manufacture procedure. Taking into account these models, the scheduling software has been designed, programmed and tested on-line. The new automation system of production scheduling has been implemented successfully at Baosteel, which produces a great economic benefit. 相似文献
1000.
The hydration characteristics and expansion impetus of three kinds of cement paste under free-and confined-curing conditions
were investigated, which were respectively mixed with three different kinds of expansive agent at low W/B ratio. The results
show that the hydration products of pure cement paste and paste mixed with expansive agent are same, but the amount of hydration
products, un-hydrated C3S and C2S are obviously different at the same hydration age. At 3 d age, the amount of CH in pure cement paste is less than that of
paste mixed with expansive agent, but it is reverse when at 28 d age. The amount of AFt at 3d and 28d age in pure cement paste
is less than those of paste mixed with expansive agent. Regardless of under free- or confined-curing condition, the amount
of ettringite produced varies little since 3d age. The joint effect of the tumefaction of gel-ettringite due to water absorption
and the expansive pressure on the pore caused by the crystalloid ettringite is the cause of the volume expansion of cement
paste, and the former effect is much greater than the latter.
LU Lin-nu : Born in 1972
Funded by 973 High-tech Project of China (No. 2001CB610704-2) and the Natural Science Foundation of Hubei Province(No. 2002AB075) 相似文献