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In the design of tolerance allocation the cost–tolerance function is usually employed to represent the objective function which is to be minimized. The traditional cost–tolerance functions in the literature are concerned with only one characteristic. In this paper we obtain a bivariate cost–tolerance function to describe the relationship between the cost and tolerances of two characteristics (i.e. the thickness and inner diameter) of a lock wheel. Then the bivariate loss function is combined with the bivariate cost–tolerance function to determine the optimal tolerances for the thickness and inner diameter of a lock wheel such that the user's potential loss/cost may be evaluated. When the quality loss is considered, the tolerances of both characteristics become tighter. By including the effect of product degradation, the present work of expected bivariate quality loss is then introduced as a quality performance measure. By assuming linear drifts on both the thickness and inner diameter of the lock wheels, the model with the present worth of quality loss leads to tighter tolerances of both characteristics. In addition, a longer planning horizon (or a longer useful life of the product) leads to tighter tolerances and a larger user's discount rate results in looser tolerances for both characteristics. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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Hsi-Ya Chang Kuo-Chan Huang Cherng-Yeu Shen Shou-Cheng Tcheng & Chaur-Yi Chou 《Computer-Aided Civil and Infrastructure Engineering》2001,16(5):365-373
Recently, the superior and continuously improving cost-performance ratio of commodity hardware and software has made PC clustering a popular alternative for high-performance computing in both academic institutes and industrial organizations. The purpose of this work is to use PC clusters to solve a weather-prediction model in parallel mode, and the result also will be compared with those obtained on some conventional parallel platforms such as the Fujitsu VPP300, IBM SP2 (160 and 120 MHz), and HP SPP2200. Techniques of domain decomposition and data communication are used to exploit parallelism of the model. Interprocessor data communication is done by the Message Passing Interface communication library routines. Two versions of the parallel codes, one with longitude decomposition and the other with latitude decomposition, are tested and compared. Speedups of the parallel weather model on these machines with various numbers of processors show that substantial reductions in computation time can be achieved as compared with sequential runs. 相似文献
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Jesse V. Jokerst Jie Chou James P. Camp Jorge Wong Alexis Lennart Amanda A. Pollard Pierre N. Floriano Nicolaos Christodoulides Glennon W. Simmons Yanjie Zhou Mehnaaz F. Ali John T. McDevitt 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(5):612-612
The slow development of cost‐effective medical microdevices with strong analytical performance characteristics is due to a lack of selective and efficient analyte capture and signaling. The recently developed programmable nano‐bio‐chip (PNBC) is a flexible detection device with analytical behavior rivaling established macroscopic methods. The PNBC system employs ≈300 μm‐diameter bead sensors composed of agarose “nanonets” that populate a microelectromechanical support structure with integrated microfluidic elements. The beads are an efficient and selective protein‐capture medium suitable for the analysis of complex fluid samples. Microscopy and computational studies probe the 3D interior of the beads. The relative contributions that the capture and detection of moieties, analyte size, and bead porosity make to signal distribution and intensity are reported. Agarose pore sizes ranging from 45 to 620 nm are examined and those near 140 nm provide optimal transport characteristics for rapid (<15 min) tests. The system exhibits efficient (99.5%) detection of bead‐bound analyte along with low (≈2%) nonspecific immobilization of the detection probe for carcinoembryonic antigen assay. Furthermore, the role analyte dimensions play in signal distribution is explored, and enhanced methods for assay building that consider the unique features of biomarker size are offered. 相似文献
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表层嵌贴预应力FRP板条加固钢筋混凝土结构技术可充分发挥FRP材料强度,且不需设置永久锚具,具有较大的潜力。以试验得到的嵌贴FRP混凝土粘结滑移关系为基础,建立了嵌贴预应力CFRP板条与混凝土的粘结应力微分方程,并根据边界条件推导了方程的解析解,得到了嵌贴预应力CFRP板条放张后界面粘结应力、CFRP拉伸应力的分析模型。与试验结果的比较表明,该模型得出的界面粘结应力及CFRP拉伸应力与试验结果吻合较好。在此基础上,考虑放张后CFRP混凝土界面不出现剥离的条件,分析了粘结界面能抵抗的最大容许预应力。 相似文献
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