BKX-Ⅰ型并联机床的谐响应分析

应用有限元分析软件(ANSYS),对BKXⅠ型并联机床进行谐响应分析,分别得到了机床各节点沿机床的虚拟轴X、Y和Z向的位移谐响应曲线。在此基础上,还分析了该机床的谐响应规律,并明确了谐响应的特点,为改善此类机床的动态特性提供了一定的参考依据。     

A new efficient numerical method and the dynamic analysis of composite laminates with piezoelectric layers

Firstly, a numerical method for the inversion of Laplace transform is developed and its accuracy is shown through examples. Then, a state-vector equation for the dynamic problems of piezoelectric plates is deduced directly from a modified mixed variational principle for piezoelectric bodies and its exact solution for the dynamic problems of simply supported rectangle piezoelectric plate is simply given. For multilayered hybrid plates, we derive the solution in terms of the propagator matrices. The techniques accounts for the compatibility of generalized displacements and generalized stresses on the interface both the elastic layers and piezoelectric layers, and the transverse shear deformation and the rotary inertia of laminate are also considered in the global algebraic equation of structure. Meanwhile, there is no restriction on the thickness and the number of layers. As an application of the numerical inversion of Laplace transform presented in this paper, typical numerical examples of the harmonic vibration and transient response are proposed and discussed. Since the highly accurate numerical results, they can serve as benchmarks to test various thick plate theories and various numerical methods, such as the finite and boundary element methods for transient response problems.     

Lactic acid production from dining‐hall food waste by Lactobacillus plantarum using response surface methodology

BACKGROUND: Food waste generally has a high starch content and is rich in nutritional compounds, including lipids and proteins. It therefore represents a potential renewable resource. In this study, dining‐hall food waste was used as a substrate for lactic acid production, and response surface methodology was employed to optimise the fermentation conditions. RESULTS: Lactic acid biosynthesis was significantly affected by the interaction of protease and temperature. Protease, temperature and CaCO₃ had significant linear effects on lactic acid production, while α‐amylase and yeast extract had insignificant effects. The optimal conditions were found to be an α‐amylase activity of 13.86 U g^?1 dried food waste, a protease activity of 2.12 U g^?1 dried food waste, a temperature of 29.31 °C and a CaCO₃ concentration of 62.67 g L^?1, which resulted in a maximum lactic acid concentration of 98.51 g L^?1 (88.75% yield). An increase in inoculum size would be appropriate for accelerating the depletion of initial soluble carbohydrate to enhance the efficiency of α‐amylase in dining‐hall food waste fermentation. CONCLUSION: A suitable regression model for lactic acid production was developed based on the experimental results. Dining‐hall food waste was found to be a good substrate for lactic acid fermentation with high product yield and without nutrient supplementation. Copyright © 2008 Society of Chemical Industry     

液晶分子附着能和盒间隙对响应时间的影响

通过理论分析和实验研究液晶分子附着能和液晶盒间隙对响应时间(τ0)的影响。用液晶盒有效间隙法和表面动力学方程法两种方法推出分析公式,由这两种方法推出的结果是一致的。实验数据与简化方程τ0-dx基本拟合(其中d是液晶盒的间隙,x是指数)。在两种极端的(极大或极小)附着能极限下,指数x分别接近2和1。这个结论有助于优化液晶显示器件的应用。     

Using visual reinforcement to establish stimulus control of responding of Siamese fighting fish (Betta splendens).

Stimulus control of ring swimming was studied with male Siamese fighting fish (Betta splendens) using 2-component multiple schedules in which the components were correlated with the presence or absence of air bubbles in the water. In Experiment 1, either response-independent mirror presentations or extinction was juxtaposed with immediate response-dependent mirror presentations. Rates of ring swimming generally were higher with immediate reinforcement than with either response-independent mirror presentations or extinction. In Experiment 2, different durations of response-dependent mirror presentations were juxtaposed. Generally, higher rates of ring swimming occurred with 15-s than with 0-, 1-, or 3-s durations. Results demonstrate that stimulus control of responding can be established with these fish under several conditions of differential reinforcement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

虚拟企业模型并行仿真研究

随着各种全新的制造理念,特别是虚拟企业的出现,企业模型的规模不断扩大,使目前存在的大多数企业模型仿真系统的效率大大下降。该文针对此问题,通过深入分析虚拟企业模型结构,并在已有的构件化企业建模体系CEMS及其仿真系统的基础上,结合异步仿真技术和多线程技术提出了一种分层式企业模型仿真体系结构,为虚拟企业模型的快速高效的仿真提供了一种有效的方法。     

三代微光管均匀性测试与分析

利用自行研制的“光电阴极多信息量测试系统”首次对国产三代微光管中的GaAs光电阴极的均匀性进行了光谱响应测试 ,结果表明该国产三代微光管存在明显的非均匀性。利用曲线拟合方法估算了GaAs光电阴极的材料性能参数 ,发现表面逸出概率不一致是非均匀性的主要原因 ,GaAs材料的少子扩散长度 (1 1 2～ 1 82 ) μm ,与阴极厚度相当 ,后界面复合速率在 (1× 1 0 5～ 1× 1 0 6 )cm/s之间 ,它限制了阴极灵敏度的提高     

Diagnosing item score patterns on a test using item response theory-based person-fit statistics.

Person-fit statistics have been proposed to investigate the fit of an item score pattern to an item response theory (IRT) model. The author investigated how these statistics can be used to detect different types of misfit. Intelligence test data were analyzed using person-fit statistics in the context of the G. Rasch (1960) model and R. J. Mokken's (1971, 1997) IRT models. The effect of the choice of an IRT model to detect misfitting item score patterns and the usefulness of person-fit statistics for diagnosis of misfit are discussed. Results showed that different types of person-fit statistics can be used to detect different kinds of person misfit. Parametric person-fit statistics had more power than nonparametric person-fit statistics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

高强度钢板在汽车车身上的应用及问题对策

主要介绍高强度钢板使用量增加背景、已开发或正在开发的种类、高强度钢板在汽车车身上的应用以及高强度钢板使用中存在的主要问题及其对策等。     

PV module dynamic impedance and its voltage and frequency dependencies

The paper presents a derivation of the dynamic impedance of a PV module. At each bias voltage, the general form of the impedance describes a semicircular locus in the complex impedance plane. Intercepts of each impedance locus yield series, shunt and dynamic resistance of a module. Determinations of the dynamic impedance of a x-Si PV module in the dark with five reverse bias voltages and over a frequency range of 1 Hz to 60 kHz are made. The experimental results validate the derived general form of dynamic impedance.