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941.
This study applies energy method to derive the system modeling of a triaxial microaccelerometer that consists of a quadri-beam
suspension, a seismic mass, and displacement transducers using piezoelectric thin films. Two suspension beams support both
ends of the seismic mass, which is fabricated by anisotropic etching of silicon. An out-of-plane acceleration will result
in a symmetric bend, and in-plane accelerations will produce asymmetric bend and torsion of the suspension beams. Two piezoelectric
thin-film transducers are arranged at both ends of each suspension beam. Eight transducers in total are interconnected such
that triaxial accelerations can be measured selectively. The structure stiffness of the suspension beams considers both the
silicon beams and piezoelectric films by the use of the laminated beam theory. Therefore, the analytical model is applicable
to the accelerometers with thick piezoelectric films. The model is based on the anisotropic material properties of Silicon
and PZT and Euler’s beam equation with the assumptions that smaller strains and stresses are negligible. The analytical results
of the resonant frequencies and sensor sensitivities to triaxial accelerations are presented and confirmed by finite element
analysis. 相似文献
942.
Wei-Lun Chang 《Knowledge》2011,24(8):1181-1186
In the past, companies changed their focus from product-oriented within marketing to demand-oriented within quality improvement. Today, they emphasize customer service, customer loyalty, and customer profitability. The significance of customer-centric services has become critical and essential. However, certain research which investigates the effect of customer lifetime value focuses only on lifetime values of existing customers. This study devises a novel model to predict customers’ prospect value. In the proposed model, we utilize the concept of finance which stands in the current status and predicts future value based on historical data. The simulated results reveal that, in a long-term simulation, customer prospect value rises when reach rate increases. Decreasing reach rate and costs result in high customer prospect value; however, the value of customer prospect value decreases in a long-term simulation. The new model complements the existing customer lifetime value model from a different perspective and provides clues to customer value for future researches. 相似文献
943.
给出了一种由方向盘转角及力矩传感器、16位∑-△型数模转换器、单片机和CAN总线芯片所组成的方向盘转角及转向力矩采集方案.阐述了A/D转换、转角及力矩值计算、CAN通讯的实现以及上位机采集软件的编写等重要过程的实现方法,在此基础上实现了对方向盘转角及转向力矩的数据采集,并进行了实际车载环境使用.应用结果表明,该系统测试... 相似文献
944.
945.
946.
We propose a nonlinear mathematical model to consider production scheduling and vehicle routing with time windows for perishable food products in the same framework. The demands at retailers are assumed stochastic and perishable goods will deteriorate once they were produced. Thus the revenue of the supplier is uncertain and depends on the value and the transaction quantity of perishable products when they are carried to retailers. The objective of this model is to maximize the expected total profit of the supplier. The optimal production quantities, the time to start producing and the vehicle routes can be determined in the model simultaneously. Furthermore, we elaborate a solution algorithm composed of the constrained Nelder–Mead method and a heuristic for the vehicle routing with time windows to solve the complex problem. Computational results indicate our algorithm is effective and efficient. 相似文献
947.
948.
949.
The objective of this study is to investigate whether work fatigue and physiological symptoms that high-elevation construction workers experience would be affected by the occupations. Questionnaires of demographic data and subjective fatigue symptoms as well as some physiological measurements were carried out, pre- and post-shift, on scaffolders, steel fixers, formworkers, electrician-plumbers, concreters and miscellaneous workers at a high-rise building construction site. This study found that some subjective fatigue symptoms coincide with the life style of some workers and that the extent of fatigue symptoms and physiological strains varies among different occupations of construction workers. Scaffolders, steel fixers and formworkers are categorized as physically demanding fatigue type of workers, while concreters, electrician-plumbers and miscellaneous workers as general type. The prevalence and occurrence of subjective fatigue symptoms indicate high-elevation workers have more complaints of “projection of physical impairment” than “drowsiness and dullness” and “difficulty in concentration”. Some unexpected changes (i.e., post-shift measurements are greater than pre-shift ones) in some strength tests in scaffolders and concreters were consistent with the observations of how they exercised their bodies during work shift. Considerable variation of average heart rate among occupations was found, with scaffolders the highest and concreters the lowest. This study concludes that questionnaires of subjective fatigue symptoms and some physiological measurements can be used as indicators to predict the extent of strains or hazards which construction workers encounter. In terms of management program of safety and health, more attention should be paid to those physically demanding workers, such as scaffolders, workers with lower sense of safety and health, such as miscellaneous workers, and workers with older age, such as concreters. 相似文献
950.
For a set S of n points in convex position in the plane, let P(S) denote the set of all plane spanning paths of S. The geometric path graph of S, denoted by Gn, is the graph with P(S) as its vertex set and two vertices P,Q∈P(S) are adjacent if and only if P and Q can be transformed to each other by means of a single edge replacement. Recently, Akl et al. [S.G. Akl, K. Islam, H. Meijer, On planar path transformation, Inform. Process. Lett. 104 (2007) 59-64] showed that the diameter of Gn is at most 2n−5. In this note, we derive the exact diameter of Gn for n?3. 相似文献