Noise analysis compact differential evolution

This article proposes a compact algorithm for optimisation in noisy environments. This algorithm has a compact structure and employs differential evolution search logic. Since it is a compact algorithm, it does not store a population of solutions but a probabilistic representation of the population. This kind of algorithmic structure can be implemented in those real-world problems characterized by memory limitations. The degree of randomization contained in the compact structure allows a robust behaviour in the presence of noise. In addition the proposed algorithm employs the noise analysis survivor selection scheme. This scheme performs an analysis of the noise and automatically performs a re-sampling of the solutions in order to ensure both reliable pairwise comparisons and a minimal cost in terms of fitness evaluations. The noise analysis component can be reliably used in noise environments affected by Gaussian noise which allow an a priori analysis of the noise features. This situation is typical of problems where the fitness is computed by means of measurement devices. An extensive comparative analysis including four different noise levels has been included. Numerical results show that the proposed algorithm displays a very good performance since it regularly succeeds at handling diverse fitness landscapes characterized by diverse noise amplitudes.     

Development of a fish‐based index of biotic integrity (FIBI) for monitoring riverine ecosystems in the Lake Victoria drainage Basin,Kenya

The long term monitoring of aquatic ecosystems based on chemical analysis is expensive resulting in a lack of time series data for management purposes thus necessitating the need for new cost effective methodologies. This study developed a fish‐based index of biotic integrity (FIBI) for monitoring environmental conditions in riverine ecosystems within the Lake Victoria Basin, Kenya. The fish fauna in the basin is poorly studied, less diverse and ecologically specialized than the temperate fauna that provided the origins of the Index of Biotic Integrity. Fish samples were collected by electrofishing from 24 sites during baseflow periods in February, March and July 2004. Validation data were collected from 7 sites with varying levels of degradation. Fish samples were identified, counted and grouped into different trophic groups, relative tolerance to pollution, habitat guild and whether exotic or native to riverine environment. Thirty‐three candidate metrics were evaluated for responsiveness to habitat quality and twelve were selected for inclusion in the final index. The index classified 6 of the 7 validation sites according to their levels of degradation. As a bioassessment tool, the index was useful in laying the basis for long‐term monitoring of rivers in the Lake Victoria drainage basin. Copyright © 2010 John Wiley & Sons, Ltd.     

水泵选型应用系统中CAD在线绘图的设计与实现

水泵选型应用研究的目的是用计算机来代替传统的纸质资料。系统地介绍了在水泵选型应用系统中利用网络进行CAD在线绘图的特点、CAD在线绘图的设计构思以及实现方法,为B/S结构的水泵选型应用系统奠定基础。     

森林保险市场的信号甄别和激励机制

基于森林保险市场存在的两种不确定因素,从减少道德风险和抑制逆向选择两方面出发,同时引入了免赔额和共保率,并对投保林主和森林进行综合风险分类,构建了一个信号甄别和激励模型,导出了一种符合森林保险市场发展需要的费率与共保率厘定体系.该方法打破了传统森林保险费率统一的定价模式.     

合肥城市高速铁路走向研究

高速铁路已成为区域大城市之间联系的重要纽带.高速铁路市区段的建设对城市的发展将产生深远影响.基于合肥城市发展的特征,重点从城市空间结构的视角,对合肥城市高速铁路走向进行多方案比较研究,并提出适宜的方案.进而指出,高速铁路市区段的选线应与城市规划相协调,引导城市良好空问结构的形成.     

When does visual attention select all features of a distractor?

What happens after visual attention is allocated to an object? Although many theories of attention assume that all of its features are selected and processed, there has been little direct evidence that an irrelevant feature dimension of an attended nontarget is processed. In 5 experiments presented here, the authors used a singleton paradigm to investigate the effect of attention on nontarget objects. Participants made a speeded feature discrimination of a target for which the response was either compatible or incompatible with an irrelevant feature dimension of a distractor. The results show that the irrelevant distractor features were processed to the point that they interfered with the response to the target. The response compatibility effect was observed even when the location of the target or the distractor was invariant, although it was much weaker when both locations were invariant. These results demonstrate that in many circumstances, an attended distractor is completely selected and fully processed, and the complete processing of distractors depends on a number of factors, many of which are related to the strength of attention to the distractor. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

闽江口湿地遥感影像最佳景观观察尺度的选择

应用遥感和地理信息系统技术,对景观最佳观察尺度选择的方法进行了探讨;构建了“定量化景观指数粒度敏感区间,定性化尺度大小,定性与定量相结合决定最佳观察尺度值“的最佳景观观察尺度选择模式,并以ASTER遥感影像为数据源,应用该模式对闽江口湿地景观最佳观察尺度进行了研究,指出闽江口湿地的景观观察尺度应以50m和100m为主,最大尺度不应超过200m.     

锅炉等离子点火技术的应用及燃油系统选择

适用于贫煤、烟煤、褐煤,可连续运行的多根碳棒等离子点火技术,较前苏联采用银棒等离子点火技术具有造价低、使用寿命长等优点。以包头第二热电厂为例,对采用等离子点火技术前后的运行情况分析比较,经济效益可观。针对丰镇电厂三期2×600MW机组,设计采用等离子无油点火技术,对燃油系统进行了优化选择,简化了油罐设置。工程具有显著的经济效益和环境效益。     

A comparative study of exchange and aggregation models in the B2B e-marketplace

This research seeks to provide an economic framework for understanding two major forms of e-marketplaces: aggregation-oriented vs. exchange-oriented e-marketplaces. By analyzing the marginal benefit per transaction in alternative models, we are able to determine the most suitable B2B e-marketplace for a wide variety of product categories, market conditions, and procurement methods. For example, when companies sell commodities in a fragmented market, the aggregation model is suitable for spot purchasing, and the exchange model works best for systematic purchasing. In addition, the effect of supplier consolidation and information technology-enabled cost reduction on model selection is discussed.     

关于最佳鉴别特征维数问题的讨论

该文对最佳鉴别特征的最佳维数问题进行了详细的讨论．文章首先对最佳维数问题进行了界定，然后指出了两种最佳特征维数为c-1维的情况即以某些基于矩的可分性判据(准则函数)为优化目标的最优特征和以某些特殊的分类器错误率为优化目标的最优特征．最后该文运用方差分析法对最佳鉴别特征进行特征选择使之代入最小距离分类器后识别率最大．