PLC控制的恒变频供水系统的使用与优势

<正>某生活小区有近千用户,就现在的供水系统而言,在用水量大的时间段,常常出现供水不足的情况,水压下降,严重影响住户的生活质量。现在的供水系统采用水泵定速控制,通过改变阀门的大小的广泛调节流量和压力,以达到水压恒定。这种方式在运行中存在三个问题。第一,人工操作存在调节滞后,整个系统稳定性差,自动化程度低,使得溢水管经常排水,造成资源浪费。第二,水泵定速运行,不仅     

长江引水三期取水泵站前池流态问题的解决方案

在通过水力模型试验后,提出了改善进水流态、提高水泵装置效率的工程措施。经实践证明:采用八字形导流墩对于大型泵站来说有其合理性,尤其在多机组工况运行时。     

变频调速装置在煤气生产中的应用

分析了煤气生产中高压氨水无烟加煤装置的运转模式及存在问题,提出了在高压氨水泵上安装变频调速装置并通过可编程序控制器自动调节高压氨水泵的运行速度,以达到降低能耗,延长设备使用寿命的目的。     

城市集中供热行业运行重点环节的政府监管

城市集中供热行业运行的政府监管需要明确重点环节与内容，围绕完善价格机制、保障市场运行、提高运行质量等核心问题实施科学监管，以提高监管效率、促进市场健康发育为主要目标，其根本在于确保城市集中供热行业运行有序、事业健康发展。     

中美国家机场系统对比研究

机场系统是航空运输系统的重要组成部分,机场系统运行效率的高低直接影响着航空运输量的大小。文章从机场系统管理体制、投资状况、机场定性、机场的管理方式和运行机制与机场的“市场化”等方面,对中美国家机场系统进行了详细论述,并在此基础上对我国的机场系统管理提出了一些合理化建议。     

公共实训基地运行模式的探索与实践

青岛市公共实训基地建设起步较早，经过6年建设、实践和探索，积累经验，不断刨新，积极探讨运作新模式，逐渐摸索出一条适应现实条件、运转高效的运行模式，提高了实训『基地的运行和使用效率，充分发挥了在高技能人才培训方面的重要作用。     

提高制度执行力的对策和建议的研究

本文从三个方面剖析了当前转变工作作风方面弱化制度执行力,影响制度刚性运行的因素。围绕如何提高制度执行能力,推进制度刚性运行,提出了三项措施。一是正确研判当前转变工作作风形势,迅速提高对制度刚性运行重要性的认识;二是围绕转变工作作风目标,通过提高学习成效,为保障制度刚性运行奠定基础;三是抓住关键环节,通过强化制度运行能力,为实施制度刚性运行加油助力。     

三相变压器的连接组别

变压器的并联运行，是指变压器的一次绕组都接在某一电压等级的公共母线上，而各变压器的二次绕组也都接在另一电压等级的公共母线上，共同向负载供电的运行方式。变压器并联运行有如下优点：一是提高了供电的可靠性。多台变压器并联运行时，如果其中一台变压器发生故障或需要检修，那么另外几台变压器可分担它的负载继续供电。二是提高运行效率。可根据电力系统中负荷的变化，调整投入并联的变压器台数，以减小电能损耗。     

高职院校教学运行模式内涵探析

本文探究了教学运行模式及高职院校教学运行模式的内涵.高职院校教学运行模式是高职院校教学运行整体过程的结构系统,应是适应校企合作、工学结合、顶岗实习人才培养模式的教学运行模式,是适应现代职业教育特点以及职业技术教育办学理念的教学运行模式.     

提升变电运行管理水平的若干思考

随着我国电网的快速发展，变电运行作为保证电网安全稳定运行的重一环，其管理水平至关重。为提升变电运行管理水平，我们制作了变电运行管理卡，以保证变电站安全运行为目的，以视觉熏陶为手段，系统优化安全运行、技能培训、文明生产等方面的视觉管理，实现了变电运行管理的“可控、在控、能控”，全面提升了变电运行科学管理水平。     

Bank Efficiency in Transitional Countries: Sensitivity to Stochastic Frontier Design

This article provides an empirical insight on the heterogeneity in the estimates of banking efficiency produced by the stochastic frontier approach. Using data from five countries of Central and Eastern Europe, we study the sensitivity of the efficiency score and the efficiency ranking to a change in the design of the frontier. We found that the average scores are significantly smaller when the transcendental logarithmic functional form is used in the profit efficiency measurement and when the scaling effect is neglected in the cost efficiency measurement. The implied bank ranking is robust to changes in the stochastic frontier definition for cost efficiency, but not for profit efficiency.     

Evaluation of technological competence and operations efficiency in the defense industry: The strategic planning of South Korea

This research aims to contribute to efficiency improvement by providing the implications for decision-making on continuous defense R&D investment strategies and acquisition methods via analyzing the current position and measuring the efficiency of overall weapon systems on technological competence and operations. This research is distinctive in comparison to previous studies because it is structured in a two-stage DEA analysis for efficiency by distinguishing between the technology and operations of the current eight fields of weapon systems and by adding the external index for government competence and market competence. In 2016, in comparison to the year 2013, the eight major weapon systems’ efficiency fields of the overall system of Korea, efficiency of technological competence, and efficiency of operations all increased. This research introduced the input and output variable that fits in with the defense industry by connecting the weapon systems efficiency with the national innovation system and the sectoral innovation system that are both projected in this industry. It also formed the concepts of technological competence efficiency and operations efficiency using the two-stage Network DEA method.     

Exploring the link between government funding and efficiency in nonprofit colleges

Previous literature has suggested that federal funding can hinder the efficiency of nonprofit organizations, but this has yet not been empirically tested. This study used a two‐stage data envelopment analysis (DEA) model to measure the efficiency of a set of private nonprofit teaching‐oriented colleges, then estimate the impact of federal and state funding on organizational efficiency. The findings indicate that, on average, increases in neither state nor federal funding effect efficiency of nonprofit colleges. Increasing state funding negatively impacted the efficiency of public colleges (N = 799). This study suggests that the challenges for nonprofits that accompany government funding may not rise to a quantifiable negative effect on efficiency.     

Efficiency, growth, and concentration: an empirical analysis of hospital markets

Taking an evolutionary view, Harold Demsetz hypothesized that firms differ persistently in efficiency and that industry concentration results from growth of efficient firms at the expense of inefficient ones. We test this idea with microdata from the hospital industry. Initial hospital efficiency and subsequent growth (and profitability) are significantly and positively related. Also, greater initial variation in hospital efficiency within local markets is positively related to subsequent growth in market concentration. Our findings support the evolutionary efficiency hypothesis, though they cannot confirm the stronger idea that variation in efficiency is the dominant explanation for changes in concentration.     

Examination of the relationship between urban form and urban eco-efficiency in china

The present study aims at exploring whether aspects of urban form are associated with urban eco-efficiency in China. Quantitative indicators relating to urban form (form, compactness ratio, elongation ratio and population density) and urban eco-efficiency (resource efficiency, environmental efficiency and overall eco-efficiency) were selected and quantified using remote sensing and data envelopment analysis methods. The urban form aspects of form and compactness ratios were positively correlated with urban eco-efficiency and resource efficiency. Conversely, the urban elongation ratio exhibited negative correlations with urban eco-efficiency and resource efficiency. Regarding environmental efficiency, no significant correlation is found with compactness though a negative correlation is found with population density. These results indicate that, within China, designing cities to be compact may be lead to increases in eco-efficiency and resource efficiency, but if the population density is too high the increased pollution costs will result in a decrease in environmental efficiency.     

The Role of Stakeholders in the Efficiency of Nonprofit Sports Clubs

This article analyzes the efficiency levels of nonprofit sports clubs through the data envelopment analysis methodology and specifically evaluates how efficient and inefficient clubs perceive the distinct contribution of stakeholders in attaining their respective levels of output efficiency. The results distinguish the varying levels of efficiency between such clubs and highlight significant differences in the roles of the local government and of associations and federations in attaining these efficiency levels. The study further suggests best practices that can be adopted by officials at inefficient clubs toward reducing or eliminating their shortfalls in efficiency.     

The Role of Progress Factors Explaining Inefficiencies in Transition Countries

This paper examines whether progress in transition has a significant effect on the economic efficiency for 24 transition countries from 1990 to 2006. It uses nine progress factors to analyze the role of the progress factors to explain inefficiencies. It also questions the effect of the transition countries that recently joined the European Union on efficiency. The results suggest that the average efficiency scores for EU-N10 are much higher than the average efficiency scores for SEE/CIS. The scores increase over time for both groups of transition countries. Reforms also contribute to efficiency in general.     

Technical efficiency estimates of Cherokee agriculture: A pre- and post-removal analysis

Although there is a large literature on the pre-removal Cherokee acculturation during the early nineteenth century there are no estimates of the technical efficiency of Cherokee agriculture. In this paper two sets of nineteenth century farming data on Cherokee households are used to estimate Shephard output distance functions and to model the determinants of Cherokee technical efficiency. Controlling for farm size, spatial heterogeneity, market orientation, and experience, technical efficiency was between 7% and 9% greater in mixed-blooded households than in full-blooded households. However, using pooled time series data of post-removal Cherokee farm households in North Carolina, Cherokee technical efficiency ranged from 0% to 4% less than the efficiency of their neighboring white farmers.     

基于数据包络分析的珠三角城市竞争力研究

本文运用可变规模的数据包络分析,采用2005-2007年珠三角城市数据从资源利用效率的角度出发对珠江三角洲城市竞争力进行评价分析。数据包络分析结果显示,整体上珠三角城市竞争力较强,但城市平均效率出现缓慢下降趋势,规模效率下降大于纯技术效率下降。