Co-current and counter-current modes for water gas shift membrane reactor

In this study the performances of a membrane reactor (MR) are estimated when both shell side stream (sweep gas) and lumen side stream are continuously either in parallel flow configuration (co-current mode) or in counter-flow configuration (counter-current mode). Two mathematical models have been formulated and steady-state mass-balance gave two-dimensional differential equations, which were solved by using the orthogonal collocation technique. Simulation results for both co-current mode and counter-current mode have been compared in terms of hydrogen molar fraction (in the shell side) vs. axial co-ordinate at different hydrogen permeances, temperatures, and lumen pressures. At the operative conditions considered, a very similar CO conversion value has been obtained for both modes.     

安徽省主要地市工业经济状况的分析研究

以第三次工业普查资料为基础,着重从地区工业经济结构与综合效益、工业企业财务状况、工业经济实力、大中型企业活力等五个方面,对安徽省主要地市的工业经济状况进行分析研究．     

基于深度神经网络的搜索引擎点击模型构建

随着富媒体展现形式被越来越多地引入搜索交互界面,搜索引擎的结果页面呈异质化和二维模块展现形式,这对传统的点击预测模型提出了巨大的挑战。针对这一情况,我们对实际搜索引擎结果页面的多模态结果进行了分析,构建了一个结合深度神经网络和点击模型的框架,该框架既包含了神经网络的特性,又利用了点击模型的预测能力。我们希望利用这个框架挖掘出多模态信息与文本信息之间的相关性,使之具有描述异质化结果和二维模块展示形式的能力。实验表明,我们的框架相较于传统的点击模型在点击预测性能上有显著提升,但由于搜索引擎的多模态结果内容复杂,仅利用多模态结果的底层特征,即使使用深度神经网络,从中能够挖据出的语义相关性较弱。     

大坝变形监控数据处理的粗差识别方法及应用效果分析

正大坝安全监控的核心就在于通过各种监控理论与方法对监测资料进行分析,建立各类监控模型及监控指标,据此定量分析大坝及坝基的安全状态,监控大坝的安全运行,使大坝在安全运行的前提下充分发挥工程效益。大坝安全监测资料是大坝运行状态的直接反应,监测值的变化与大坝运行的环境荷载以及大坝本身结构形态有关,同时监测系统的稳定性也是重要的影响因素。大坝监测数据的异常一般由结构形态变化、环境量异常、系统改造、人为误测、误计或系统故障等     

PHY-CRAM物理层激励响应认证机制的性能分析

物理层认证是利用物理层资源的特性识别通信用户身份,可以有效地阻止非法用户的接入与访问,加强无线网络的信息安全性。PHY-CRAM是最近提出的一种典型的物理层激励响应认证机制,目前其性能主要依赖于仿真。尝试对其认证性能进行理论分析,推导了成功认证概率和错误接收概率的解析表达式。推导结果表明:PHY-CRAM认证准则中的相关系数服从莱斯分布,成功认证概率和错误接收概率均可用Marcum Q函数来计算。进一步的计算机仿真结果显示:相关系数的概率密度曲线与莱斯分布的概率密度曲线相吻合,且认证使用的密钥越长,吻合性越好;接收操作特性(ROC)曲线的理论值和统计值是一致的。     

Tuning algorithms for fractional order internal model controllers for time delay processes

This paper presents two tuning algorithms for fractional-order internal model control (IMC) controllers for time delay processes. The two tuning algorithms are based on two specific closed-loop control configurations: the IMC control structure and the Smith predictor structure. In the latter, the equivalency between IMC and Smith predictor control structures is used to tune a fractional-order IMC controller as the primary controller of the Smith predictor structure. Fractional-order IMC controllers are designed in both cases in order to enhance the closed-loop performance and robustness of classical integer order IMC controllers. The tuning procedures are exemplified for both single-input-single-output as well as multivariable processes, described by first-order and second-order transfer functions with time delays. Different numerical examples are provided, including a general multivariable time delay process. Integer order IMC controllers are designed in each case, as well as fractional-order IMC controllers. The simulation results show that the proposed fractional-order IMC controller ensures an increased robustness to modelling uncertainties. Experimental results are also provided, for the design of a multivariable fractional-order IMC controller in a Smith predictor structure for a quadruple-tank system.     

VBA在成绩分析中的应用

介绍在Excel平台上利用VBA开发成绩分析的过程,实现了计算机对数据的自动化处理,包括自动计算最高分、最低分、平均分、统计各分数段的人数及所占的百分比,提高了工作效率和准确性。     

E-commerce system quality assessment using a model based on ISO 9126 and Belief Networks

As business transitions into the new economy, e-system successful use has become a strategic goal. Especially in business to consumer (e-commerce) applications, users highly evaluate the quality of their interactive shopping experience. However, quality is difficult to define and measure and most importantly, it is difficult to measure its impact on the end-user. Among the many research questions that arise, some of the most important concern the exact nature of the quality attributes that define an e-commerce system, and how one could model these attributes in order to increase its acceptance. Bearing in mind that e-commerce systems are actually user/data-intensive web-based software systems, this work performed a survey which resulted in a theoretical model that helps to measure such systems’ dynamics through their decomposition into primary quality characteristics. The proposed model is based on Bayesian Networks and ISO 9126. Besides the emphasis on specific software quality attributes, it also provides a quality assessment process aiding developers to design and produce e-commerce systems of high quality. Using a Bayesian Network the model can be used to combine different types of evidences and provide reasoning from effect to cause and vice versa.

Rehabilitation of an unloved child: semi‐splaying

Splay trees are widely considered as the classic examples of self‐adjusting binary search trees and are part of most courses on data structures and algorithms. Already in the first seminal paper on splay trees (J. Assoc. Comput. Mach. 1985; 32(3):652–686) alternative operations were introduced, among which is semi‐splaying. On the one hand, the analysis of semi‐splaying gives a smaller constant for the amortized complexity, but on the other hand the authors write: Whether any version of semi‐splaying is an improvement over splaying depends on the access sequence. Semi‐splaying may be better when the access pattern is stable, but splaying adapts much faster to changes in usage. Maybe this sentence was the reason that nobody seriously ran tests to compare the performance of semi‐splaying and splaying. Semi‐splaying is conceptually simpler than splaying, has the same asymptotic amortized complexity and, as will be clear from empirical data presented in this paper, the practical performance is better for a very broad variety of access patterns. Therefore, its efficiency is a good reason to use semi‐splaying for applications instead of its more prominent brother. Moreover, its simplicity also makes it very attractive for teaching purposes. Copyright © 2008 John Wiley & Sons, Ltd.     

Optimization method for the inverse problem of reconstructing the source term in a parabolic equation

This work investigates the inverse problem of reconstructing a spacewise dependent heat source in the parabolic heat equation using a final temperature measurement. Such problem has important application in a large field of applied science. On the basis of the optimal control framework, the existence and necessary condition of the minimizer for the cost functional are established. The global uniqueness and stability of the minimizer are deduced from the necessary condition. The Landweber iteration algorithm is applied to the inverse problem and some numerical results are presented for various typical test examples.