融合对象颜色和边缘特征的图像检索

由于图像内容特性的复杂性,对图像特征的抽取、索引及检索匹配计算量巨大,空问模型向量动辄几百上千维,使基于内容的图像信息检索在Internet上的应用面临着所谓的“维数灾难“问题。提出了一个新的图像检索模型,该模型融合了颜色的空间分布信息和对象的形状特征。颜色特征采用改进的HSV模型——扇形模型描述;对象的边缘特征采用Canny方法进行计算,并通过Hough变换产生描述对象形状特征(相对位置和方向)的空间信息;图像的相似性比较采用两个全局性向量距离描述。实验结果表明,该模型比采用单一特征(颜色)具有更高的检索效率,是高效率和合理检准率的良好折中。     

The persistence of efficiency

Profits can persist in the resource-based view (RBV) of the firm because of heterogeneity of inputs combined with resource immobility. The firm-efficiency interpretation of the RBV posits that heterogeneity in, for example, technology or know-how, leads to inter-firm efficiency differences which can persist because of imperfect imitability. Thus the persistence of efficiency leads to the persistence of profitability. There has been no empirical research into the firm-efficiency view, and this paper therefore fills that gap by utilizing a panel of 4280 firms in the manufacturing sector over the period 1983–2003. Efficiency scores are derived using data envelopment analysis (DEA) and these are then modelled in a random parameter framework where one determinant of current period efficiency is the firm’s own lagged efficiency. The estimated coefficient of efficiency persistence is found to be around 0.7, thereby offering support for the firm-efficiency view, and this varies by country and by industry.     

Evaluating knowledge and capacity development in the water sector: challenges and progress

As knowledge and capacity development (KCD) is increasingly acknowledged as crucial for development, the need to evaluate its impact increases, too. However, evaluating KCD in practice remains a challenge. This article aims to synthesize the current wisdom on the topic of KCD evaluation in the water sector. We discuss two leading approaches to KCD (positivist and complex adaptive systems) and their associated evaluation paradigms, the major methodological challenges facing KCD evaluation, and progress made in that respect. The article provides insights for KCD practitioners and policy makers in the water sector that can help them improve their KCD evaluation practice.     

Improved Analysis of Co-Channel Interference in Cellular Communications Systems

1 Introduction The performance analysis of co-channel interferenceincellular systems has been actively researched in the lastfewyears , due to the rapid deployment and success ofsuch systems , and because of the scarce bandwidthwhich calls for very careful design tools in order to uti-lizeit most efficiently.Signal transmission over a mobilechannel often suffers fromshadowing effect ,causing byobstacles in the radio propagation, such as the build-ings .In a cellular mobile system,the problemis…     

煤矿铁路曲线地段养护方法的探讨

结合我部现有铁路曲线地段的常见病害,进行全面分析其生成原因,提出相应的养护方法及达到的效果。     

So what are master's-level psychology practitioners doing? Surveys of employers and recent graduates in North Carolina.

In response to questions regarding the marketability of master's-level psychology practitioners, 2 surveys were conducted: 1 of prospective employers of master's-level psychologists and 1 of recent graduates of the University of North Carolina system's master's in psychology programs with clinical emphases. Results indicate that graduates face a healthy job market in the public sector and have a good reputation for value in the marketplace. Graduates reported finding desirable work shortly after graduation, primarily in the public sector. Few described any difficulties with the state-mandated supervision requirement or managed-care reimbursement, perhaps because most public-sector settings provided for both. The data represent the collaborative effort of 1 state's university-system's psychology master's programs to assess employment experiences and marketplace trends. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

扇形铅黏弹性阻尼器综合设计及加固框架抗震性能分析

为研究扇形铅黏弹性阻尼器与加固框架结构之间的匹配关系及其对加固框架抗震性能的影响规律,用ABAQUS软件建立了对比空框架和加固框架的精细化有限元模型,结合试验试件骨架曲线及破坏形态验证了其合理性。提出扇形铅黏弹性阻尼器加固框架的综合设计原则,设定阻尼器扇形有效半径与框架柱净高之比为设计尺寸比,在此基础上,对不同设计尺寸比的加固框架进行对比分析。分析结果表明,合理设置的扇形铅黏弹性阻尼器可以显著提高加固框架的抗震性能,保护梁柱节点核心区;当设计尺寸比取值超过0.24时,会导致加固试件较早达到峰值荷载,但其后承载力又急剧衰减;建议扇形铅黏弹性阻尼器加固框架的设计尺寸比宜控制在0.1~0.2之间,实际设计中应依据不同加固需求选取相应的设计尺寸比。     

Household electricity demand in Latin America and the Caribbean: A meta-analysis of price elasticity

Studying the price elasticity of demand is essential when considering rate policies in the electricity sector. This research aims to perform a meta-analysis and a meta-regression of the price elasticity of electricity demand for the residential sector in Latin American and Caribbean countries. Results show that the true value of the short-term price elasticity is between −0.197 and −0.468 and, for the long-term, is between −0.252 and −0.331. Findings differ substantially when studies are classified by their quality in econometric procedures. The long-term price elasticity seems to be lower than estimates found for other regions.     

Comparative Performance of Different Sector Arrangement in a Desiccant Wheel Using a Mathematical Model

A one‐dimensional mathematical model has been used for a three‐sector desiccant wheel (two sectors with purge) with different flow arrangements. The model considers both gas and solid side resistance and shows a good agreement with experimental results. This model has been used to conduct a comparative performance analysis in both the effective adsorption and effective regeneration sector of a desiccant wheel. It was found that an effective regeneration sector gives better results for the performance parameters (rotation of wheel, regeneration temperature, velocity, and ambient moisture) as compared to an effective adsorption sector. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21103     

新能源行业政府补贴对企业创新绩效的影响

“十四五”计划在原有国民经济和社会发展规划的基础上,进一步强调了创新、绿色在新发展理念中的重要地位。政府补贴,作为政府支持企业研发活动的重要政策工具之一,激励企业加大研发投入,增强企业创新动力。为探究不同产权性质调节下,政府补贴如何影响新能源企业创新绩效,以及将三者纳入同一框架下,考虑研发投入作为中介变量对企业创新绩效的影响。选取CSMAR数据库和wind数据库2015—2019年高研发投入、低短期经济效益的战略性新兴产业中的106家国有与非国有产权性质的新能源企业,进行面板数据分析。被解释变量为企业创新绩效,解释变量为政府补贴,调节变量为产权性质,中介变量为研发投入强度,通过对新能源行业政府补贴的研究,以检验在研发投入强度作为中介效应,企业产权性质作为调节作用时政府补贴对企业创新绩效的影响。研究结果显示,政府补贴与新能源行业的创新绩效呈正相关关系,研发投入强度在政府补贴与企业创新绩效之间发挥着部分中介作用,且不同企业产权性质的新能源企业,在政府补贴与企业创新绩效之间存在显著差异。根据上述结论提出：1）在市场经济下,政府补贴是保证新能源企业生存以及促进其发展的直接激励方式,因此建议政府应在合理监管下持续对新能源企业提供有效财税和金融等政策补贴;2）由于部分新能源企业违规将政府补贴转移到非研发投入中,从而使得政府补贴失灵,因此在国家后续政策法规出台后需细化新能源企业获得政府补贴后的使用路径;3）相比于国有企业非国有企业可获得的资源较少,市场风险抵御能力较弱,因此政府在进行补贴激励时可以重点倾斜给非国有企业以促进其产出更高的创新绩效。