Time-domain analysis of gravity dam–reservoir interaction using high-order doubly asymptotic open boundary

A procedure for the time-domain analysis of gravity dam–reservoir interaction is proposed. The dam and a part of the reservoir with irregular geometry are modeled with finite elements. A high-order doubly asymptotic open boundary condition is developed to model the remaining part of the reservoir simplified as a semi-infinite layer of constant depth. This open boundary is temporally local, stable and converges rapidly as the order increases. It is directly coupled with the commercial software ABAQUS by using a sequential staggered implicit-implicit partition algorithm. Numerical examples demonstrate the high accuracy and long-time stability of the proposed technique.     

Chaotic Bayesian optimal prediction method and its application in hydrological time series

The embedding dimension and the number of nearest neighbors are very important parameters in the prediction of chaotic time series. To reduce the prediction errors and the uncertainties in the determination of the above parameters, a new chaos Bayesian optimal prediction method (CBOPM) is proposed by choosing optimal parameters in the local linear prediction method (LLPM) and improving the prediction accuracy with Bayesian theory. In the new method, the embedding dimension and the number of nearest neighbors are combined as a parameter set. The optimal parameters are selected by mean relative error (MRE) and correlation coefficient (CC) indices according to optimization criteria. Real hydrological time series are taken to examine the new method. The prediction results indicate that CBOPM can choose the optimal parameters adaptively in the prediction process. Compared with several LLPM models, the CBOPM has higher prediction accuracy in predicting hydrological time series.     

Effects of eccentricity,temperature, velocity,and polymer properties on solids compressibility in vane extruder

An experimental instrument is developed with a purpose to study solids compaction behaviors in vane extruder in a direct manner. The effects of eccentricity, temperature, velocity, and polymer properties on the compressibility of polymer solids are reported in terms of compaction coefficient as a function of rotor torque. The results show that a relatively larger eccentricity or a lower external temperature can bring a smaller compaction coefficient, which results in higher pressure in the solids conveying zone of the vane extruder. However, rotor velocities almost have no influence on the compaction coefficient under the same condition. In addition, a difference is observed between the effects of the semicrystalline polymers and the noncrystalline polymers on the compaction coefficient, which should be taken into consideration in vane extrusion processing operations. POLYM. ENG. SCI., 54:1403–1411, 2014. © 2013 Society of Plastics Engineers     

Pellicle formation,microbial succession and lactic acid utilisation during the aerobic deteriorating process of Sichuan pickle

The pellicles formation, microbial changes and lactic acid utilisation during the aerobic deterioration of Sichuan pickle were discussed in this study. By plate counting, chemical detection and HPLC analysis, the aerobic deterioration of Sichuan pickle was featured by microbial growth, pellicle formation, lactic acid decrease and pH elevation. Bacteria dominated in pellicles and the pellicles present morphological change from smooth to wrinkly along with the aerobic deteriorating process. Nine species of bacteria were identified and responsible for the pellicle formation. Combined with Lactobacillus plantarum, eight pellicle‐forming bacteria were the dominant lactic acid consuming organisms in deteriorating Sichuan pickle. Especially under the harsh acid condition of the early deteriorating period, Lb. plantarum, pellicle‐forming bacteria Bacillus amyloliquefaciens, B. subtilis and Citrobacter freundii participated in the pellicles, utilised lactic acid and increased the brine pH effectively. Sequence analysis of 16S rDNA libraries suggested that the resulting pH of 4.8–5.0 initiated the growth of more undesirable organisms, and the pellicle bacterial diversity changed greatly compared with that in the early deteriorating period. The study indicated the important role of pellicles in the initiation of Sichuan pickle's aerobic deterioration and enhanced our ability to understand and potentially control the aerobic deterioration.     

钛合金亚β锻造与热处理组织与性能的研究

钛合金经不同锻造—热处理规范加工后,其显微组织的变化是比较复杂的,尤其是亚β锻造以后研获得的网篮组织的形态是多种多样的。本文研究的是TC6、TC11钛合金加热到高于β相变点及接近β相变温度开始进行的变形及在(α β)两相区终锻并经等温退火后,其显微组织的特殊变化,同时比较分析不同热处理后的组织一性能关系,为在生产实践中制订热加工工艺规范提供可靠的依据,以便充分挖掘钛合金性能方面的潜力。     

计算机辅助制定工时定额系统

本文阐述以我院为主开发的,人机会话式的计算机辅助制定工时定额系统。该系统在 APPLE-Ⅱ机上运行,用 BASIC 语言编写。本文介绍主要程序框图和相互之间的关系。采用该系统,可以显著地提高定额工作的效率,用计算机快速地制定出准确、统一的工时定额、系统操作简便,效益显著。     

直流数字电压表低量限检定线路的改进及测量不确定度评定

本文详细地叙述了利用YJV—1直流标准电压源作为信号源采用比较法检定直流数字电压表低量值时所存在的问题,并设计一种改进电路,同时按照JJF1059-1999《测量不确定度评定与表示》规范的要求,对上述方法中所阐述的直流数字电压表低量值部分示值误差测量结果的不确定度进行了评定。     

聚合物/粘土纳米复合材料研究进展

概述了近年来聚合物 /粘土纳米复合材料的研究进展 ,根据插层机理和方法的差别 ,将插层法分为 3类 :(1)单体原位插层复合 ;(2 )溶液中聚合物插层复合 ;(3)熔融聚合物插层复合。提出了利用双螺杆挤出机熔融挤出制备聚合物 /粘土纳米复合材料的新方法。并总结了聚合物 /粘土纳米复合材料的性能开发及应用前景。     

基于海明神经网的电压-无功功率自动调节理论的研究

本文引入了人工神经网络（海明网络），利用状态分类来解决变电站电压-无功功率双参数控制中的边界问题。     

河冰生消演变及其运动规律的研究进展

河冰是在特定的气象条件、地形河势和水力作用下产生的自然现象。研究河冰生消演变及其运动规律 ,从而根据气象、水文、冰情历史资料、现时信息和河道特征 ,应用热力学和水力学原理 ,对各种冰情要素进行预报 ,防治冰凌危害 ,是寒冷地区国家发展中必须考虑的一个重要问题。本文对河道中冰的形成、演变发展、输移、积聚堆积、消融和破碎冲蚀等各种冰情现象及其研究现状进行了分析总结 ,着重介绍国外最近的研究成果。