应用软件的加密技术及其使用

本文从加密技术和基本特征出发,使用对磁盘局部特殊格式化和应用程序软加密相结合方法,取得了简单易行、实用有效,并且灵活变化的效果。     

生产率难题与家庭生产模型

在家庭生产模型中，存在着市场部门与家庭部门之间的劳动替代，这就提高了模型解释现场经济的能力，如果发生家庭生产率冲击，且这种冲击与市场生产率不完全相关，那么随着家庭生产率的相对变化了市场部门即定工资的工人愿意提供的劳动量，劳动供给将会发生变化，这就降低了市场生产率与工作时数之间的相关性。     

合肥同步辐射光源储存环真空系统改造段的设计

合肥同步辐射光源（HLS）安装了一台6T超导扭摆磁铁。原储存环真空系统的1／8必须由改造段更换。改造段设计中遇到了新问题，如超导扭摆磁铁发出的同步辐射光的光通路和电子束流通道的确定，吸收同步辐射光的吸收器的设计，同步辐射光的光电解吸气载的计算，改造段真空室截面的平滑过渡的实现和超导扭摆磁铁77K低温束流管道的特殊问题等。     

双电压合成矩阵变换器特性与电压扇区的关系分析

在双电压合成矩阵变换器中,需要将每个周期内的输入、输出电压划分成若干扇区。根据不同的划分方法,扇区的形状可以是S形或X形。首先对双电压合成方程的一般形式占空比的计算方法进行了改进。然后研究了输入、输出电压扇区形状的四种组合即{X,X}、{X,S}、{S,X}、{S,S}。针对每一种组合研究了矩阵变换器特性与相应扇区组合的关系。这些特性包括“原点开关”的存在性、最大电压增益及输入电流波形。通过分析比较得出,最佳输入、输出电压扇区组合是{S,X}。这种组合存在“原点开关”。便于实现,能够同时获得最大的电压增益和对称的正弦输入电流,功率因数可以达到1。通过仿真分析验证了结论的正确性。     

大型湖泊富营养化试验装置能耗分析与基于PLC控制的节能改造技术

分析了大型湖泊富营养化试验装置温度控制系统的结构和原理,指出了造成该系统高能耗的根本原因.提出了详细的结构和温控改造方案.通过改变原系统独立连续的恒温循环控制方案为按需联动间歇式的高低温循环控制方案,降低了系统的运行能耗.以原系统中的温控器作为温度处理单元,利用PLC接收各温控器的输出状态信号,产生相应执行动作信号实现系统的温度控制.试验结果表明,该系统节约能耗50%以上.     

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。     

Science-based Firms Going Public: The Role of Patent Indicators and Top Management Teams

This paper examines how specific dimensions related to innovative capabilities influence the economic value of science-based firms when they go public. To test a set of hypotheses, we conduct an empirical research of a sample of dedicated biotechnology firms that completed an initial public offering (IPO) in the USA during 1983–2009. The results indicate that technological diversity, the patent stock’s value and dominant functional diversity in top management teams (TMTs) are positively associated with raising funds through an IPO. However, intrapersonal functional diversity in the TMT does not have a significant effect.     

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.     

Performance of symmetric polygonal fins with and without tip loss — A comparison of different methods of prediction

No analytical solution exists for estimating the efficiency of symmetric polygonal fins (SPFs) circumscribing circular tubes. Performance of such fins is conventionally determined from either of the two approximate techniques, namely, the equivalent annulus method and the sector method. The present work aims to judge the relative merits and applicability of these two methods critically. To this end, the results obtained from the approximate techniques have compared with those obtained from a semi‐analytical technique. It has been noted that, with the increase of the tip heat loss, the accuracy of prediction from any of the approximate methods decreases. For the sector method, a modification has been suggested. The prediction from the modified version of the sector method is always more accurate than that from the equivalent annulus method. It has been further illustrated that though the approximate techniques can be employed for the prediction of efficiency, they cannot be used to predict the tip temperatures accurately.