Modeling and simulation of shear resistance of R/C beams using artificial neural network

Artificial neural network (ANN) has been used in several engineering application areas including civil engineering. The use of ANN to predict the behavior of reinforced concrete (R/C) members, using the vast amount of experimental data as a test-bed for learning and verification of results, proved to be a viable method for carrying out parametric studies. This paper presents application of ANN for predicting the shear resistance of rectangular R/C beams. Six parameters that influence the shear resistance of beams, mainly shear-span-to-depth ratio, concrete strength, longitudinal reinforcement, shear reinforcement, beam depth and beam width, are used as input for the ANN. A back propagation neural network (BPNN) with different activation functions is used and their results are compared. The sigmoid function with variable threshold is adopted due to its accuracy of prediction. The ANN prediction and the measured experimental values are compared with the shear strength predictions of ACI318-02 and BS8110 codes. A sensitivity study of the parameters that affect shear strength of R/C beams is carried out and the underlying complex nonlinear relationships among these parameters were investigated. Shear response curves and surfaces based on these parameters were generated. It is concluded that ANN can predict, to a great degree of accuracy, the shear resistance of rectangular R/C beams and it is a viable tool for carrying out parametric study of shear behavior of R/C beams.     

采用络合滴定法与原子吸收光谱法测定皮蛋中的铅含量

文章采用络合滴定法测定和原子吸收光谱法测定皮蛋中铅的含量,结果表明:络合滴定法测定法过程简单易行,结果重现性强,准确度高,适用于铅含量相对较高的皮蛋中铅的测定。而原子吸收光谱法灵敏度高,可以检出皮蛋中少量的铅含量。市面上散装的皮蛋铅含量远超国家安全标准。     

基于SPA的同异反科研管理理论及应用

本文初步探讨了基于集对分析（ＳＰＡ）的同异反科研管理理论及其在高校科研管理中的应用。     

西藏地区高压灭菌柜应用状况

对西藏地区二十六家医院四种类型一百零一台高压消毒灭菌装置的应用及各型优劣状况进行调查、统计、对比，西藏地区相对滞后。     

Absorptive capacity and the reach of collaboration in high technology small firms

The current paper is concerned with exploring the role of absorptive capacity in extending the reach of innovation-related collaboration in high technology small firms. Drawing on survey data from a sample of 316 Dutch high-tech small firms, engaged in 1245 collaborations, we explore the relationship between R&D expenditure and distance to collaboration partners. In general terms, we find most partners to be ‘local’. However, controlling for a variety of potential influences, higher R&D expenditure is positively related to collaboration with more distant organizations. The implications of our results for policy, practice and future research are discussed.     

基于PLC（FX2N）T、C、D设定值的改变及显示设计

文章针对PLC控制系统中T、C、D软元件数据常频繁改变的特点,介绍了一种利用变址寄存器V预先设定T（C或者D）的软元件序号,并根据设定的序号,改变用户程序中的T（C或者D）的设定值并显示。     

Measurement of expansin activity and plant cell wall creep by using a commercial texture analyzer

BackgroundExpansins play an important role in cell wall metabolism and fruit softening. Determination of expansin activity is a challenging problem since it depends on measuring cell wall properties by using ad hoc extensometers, a fact that has strongly restricted its study. Then, the objective of the work was to adapt a methodology to measure cell wall creep and expansin activity using a commercial texture meter, equipped with miniature tensile grips and an ad hoc cuvette of easy construction.ResultsIt was possible to measure hypocotyls acid growth and expansin activity in a reliable and reproducible way, using a commercial texture meter, common equipment found in laboratories of food science or postharvest technology. Expansin activity was detected in protein extracts from cucumber hypocotyls, tomato and strawberry fruits, and statistical differences in expansin activity were found in both fruit models at different ripening stages.ConclusionsThe possibility of measuring expansin activity following this adapted protocol with a commercial texture meter could contribute to ease and increase the analysis of expansin in different systems, leading to a better understanding of the properties of these proteins under different experimental conditions.