进口变频器在集中供热中的应用

对变频器在集中供热系统的应用情况作了介绍，对进口变频器的工作原理进行了示说明，从而说明了进口变频器在节能、高效、安全、数字显示等方面体现了更大的优越性，在使用中出现的散热问题，电磁干扰问题，操作问题和参数设置问题等进行了认真分析，从中找出了出现总是的原因，并积累了一些经验。     

恒压供水软启动节能控制系统设计

针对变频软启动在工程应用中存在的问题，分析了变频器依次启动多台电动机的切换问题，提出一种采用变频器和软启动器共同控制的恒压供水软启动系统，达到了较好的软启动效果，实现了泵控节能目的。     

变频器常见故障处理及维护

随着当前经济的快速发展。近几年来，市场的各种类型的变频器在各行各业得到了很多企业广泛地应用，本文结合工作实践，对一些变频器的通用问题与处理进行分析。     

基于PWM变频器的电动机端过电压研究

研究了PWM变频器通过长电缆驱动电动机时的电动机端过电压问题。理论分析表明，由于电缆分布参数的影响，电动机端会出现电压反射现象，从而造成电动机端过电压，导致线圈绝缘失效。提出了一种变频器输出端的无源滤波器，通过控制变频器输出电压脉冲的上升时间达到抑制电动机端过电压的目的，并采用11kw的电梯系统验证了该滤波器的有效性及可行性。     

高压变频器研究与应用

简要介绍高压变频器分类，比较电压源型变频器和电流源型变频器技术特点。结合项目案例，探讨高压变频器的设计选型，包括启动运行、切换方式等。     

电梯变频器安装应注意的事项

交流调压调频电梯以其节能、舒适感好赢得了越来越多用户的信赖，应用越来越广泛。其中变频器是交流调压调频电梯的主要部件，但有部分用户由于对其安装或维护不当，造成变频器短路烧毁、对控制线路产生影响而停梯、雷雨天气造成经常停梯等故障时有发生。本文结合实际，谈一谈对电梯变频器安装过程中应注意的几个方面的问题。     

变频器在安装中应注意的几个问题

介绍了变频器安装前的准备工作,提出了变频器安装的一般要求,强调了变频器安装中应注意的几个问题,以保证变频器的安装质量,从而保证变频器正常工作,具有一定的参考价值。     

变频器在中小城市污水处理厂运行调节和节能改造中的应用

县级城市以上建成的中小型污水处理厂运行中遇到水量不足、难以实现稳定达标的问题，通过利用变频器控制设备进行系统调试可以实现稳定达标运行。实践表明，充分发挥变频器调速作用有利于污水处理厂在低于设计负荷情况下实现正常运行和节能。     

变频器的节能原理及在浮法玻璃生产线中的应用

对变频器的功率因数问题、变频器的节能原理进行了分析,简单介绍了变频器在浮法玻璃生产线中的应用及经济效益分析。     

浅谈变频器运行过程中存在的问题及其对策

针对大功率设备应用变频器运行过程中存在的谐波问题、负载匹配问题和发热问题,逐一进行了分析,并提出了相对应的解决方案,以推广变频器的应用,充分发挥变频器节约能源和投资少的优点。     

Intersections of inequality in homeownership in Sweden

Abstract

Inequalities relating to ownership of housing have become a major issue de jour in many Western societies. This article examines how the distribution of homeownership in Sweden relates to two factors widely seen as significant to such inequalities, namely parental tenure status and place of birth. We use longitudinal registry data to examine the bearing of these two factors on individual-level tenure progression since the beginning of the 1990s for persons at different stages of their housing careers. We extend existing understandings of Swedish homeownership patterns by demonstrating that inequalities relating to place of birth and parental tenure intersect with one another in ways that substantially advantage certain subgroups while disadvantaging others, and by demonstrating that experiences of entry into homeownership have in recent years been changing in markedly different ways for these different subgroups. Overall, Swedish homeownership inequalities, far from dissipating, appear to be hardening along existing lines.     

Living in and leaving poor neighbourhood conditions in England

Current neighbourhood renewal and urban policies in the UK seek to improve neighbourhood conditions in poor areas and achieve greater residential stability. Using one of the few longitudinal housing datasets available in the UK, this paper analyses the influence of residential perceptions on house moving behaviour in poor and other areas. It is found that residential dissatisfaction is notably higher among residents of poor areas, and they respond to poor neighbourhood conditions in the same way as the general population. Dissatisfaction with the home itself, and unhappiness with disorder in the immediate surroundings both significantly increased the odds that someone would move home. Perceived neighbourhood decline was also found to increase the odds that someone wished to move home but to reduce the likelihood that they would actually do so. Residential mobility was found to be a particular problem for owner occupiers in declining neighbourhoods and for residents in deprived parts of inner London.     

Local associations and participation in place: change and continuity in the relationship between state and civil society in twentieth-century Britain

This paper uses a review of evidence relating to the history of local civic associations to address the temporally and geographically variable relationship between state and civil society. We focus particularly on the historical development of participative practices, thus also contributing to contemporary debate about the potentials of increased community involvement in place-making. The paper has three primary purposes. First, we assess the role that local associations have played in advancing planning and conservation agendas. Second, we discuss the differing modes of participation that are most visible in the work of local groups. Third, we use a focus on the discussions of participation that took place in the late 1960s, which raised explicit questions about the relations between local state and civil society, to explore a series of problematics relating to the promise and the practice of participation. We argue that in seeking to understand both the past and the present of local associational involvement in place-making and management it is important to recognize that local groups have variable professional and social resources that lead to differences in their ability to engage in local governance. We also argue that this sphere of voluntary activity exhibits continuities with longer term practice, rather than the paradigm shift that is sometimes described in accounts of the development of participation.     

Trends in productivity improvement in the US construction industry

Surveys of the top 400 US contractors were conducted in 1979, 1983 and 1993 to identify the areas with potential for productivity improvement in the construction industry. The trends in the findings of these surveys are observed and interpreted. The results indicate that cost control, scheduling, design practices, labour training, and quality control are the functions that consistently over the years are perceived as having considerable room for productivity improvement, whereas materials packaging and foreign developments in construction technologies are perceived consistently as functions that do not have much effect on improving construction productivity. The functions that were identified as needing more improvement in 1993 compared with the previous surveys were prefabrication, new materials, value engineering, specifications, labour availability, labour training, and quality control, whereas those that were identified as needing less improvement than in the previous surveys were field inspection and labour contract agreements. Also, respondents indicated consistently over the years that they are willing to participate in activities related to improving construction productivity but are not interested in funding any such activities.     

Variation in property taxation in Tulsa

Conclusions It may be reasonably concluded from this study that the range of variation in these ratios of assessed to actual value are of a reasonable size for the great majority of cases. The frequency distribution of these sample ratios was not normal, however, as was assumed a process of this type would produce. On the other hand, the failure of the regression analysis to identify any significant variables which would explain these variations would tend to re-enforce the assumption that the fluctuations were indeed of a random nature.To sum it up in one paragraph, aside from a few extreme cases, the assessing process appears to give estimates which are more consistent than would be expected under the assumption that any errors would be of a random nature, but the regression analysis was unable to isolate any particular socioeconomic characteristics which would explain the variation which was present.Financial support for this research project was furnished by the University of Tulsa.     

Design-and-build contractors' service quality in public projects in Singapore

In the construction industry, total quality comprises corporate service quality, project service quality and quality of the constructed facility. This study investigates the project service quality of design-and-build (D&B) contractors when undertaking projects for public sector clients in Singapore. Service quality is operationalized into five determinants: reliability, responsiveness, assurance, empathy and tangible. From these, 34 attributes that may affect project service quality in D&B projects are identified. A questionnaire is used to ascertain clients' service quality expectations of these 34 attributes. The clients were also asked the extent to which D&B contractors achieve project service quality. It is found that D&B contractors did not meet clients' expectations in all the five dimensions of service quality. This means that D&B contractors are not giving clients the satisfaction that they hope for. This study offers D&B contractors feedback relating to clients' expectations of their service delivery and the areas of service that need to be improved in order to provide quality service that will satisfy public sector clients.     

Advanced lighting simulation in architectural design in the tropics

This paper outlines a 2-year research program that the team attempted to apply one of the most powerful computational lighting simulation softwares, radiance, to assist in the daylighting design of an actual building in the tropics. The validation studies, which were carried out in the Asian Civilisation Museum (ACM) in Singapore, showed that radiance can be used to predict the internal illuminance with a high degree of accuracy under overcast sky conditions. The experimental application of radiance to daylighting investigation of the ACM further supports its capabilities as well as its accuracy. Using radiance to study two daylighting control options (curtains and louvers), it can be found that louvers are more effective than curtains as daylighting control devices, and that the angle of the louvers have more effect than their reflectance on daylight penetration and distribution.     

全球化语境中的青岛旧城更新

在全球化语境中,青岛旧城更新应保持历史文化名城的地方性和多样性,维护旧城不同时代多种风格建筑新旧对立混合并存的建设格局,对整体街区环境意象和旧城格局肌理的宏观控制,使传统街区在有机更新中适应现代生活。     

Developer behavior in local infrastructure provision in Indonesia: Implications for policy

Residential areas in Indonesia face many challenges related to the adequacy and quality of infrastructure due to the limited scope of policies that regulate infrastructure provision by housing project developers. The analysis explores the role of developers in local-scale infrastructure provision. We adapt multi-criteria decision analysis to survey data for Indonesia. The analysis finds that the private developer's attitude is the top-ranking factor influencing their behavior in providing local infrastructure that is up to standard. This study proposes the elements that must be regulated and detailed in local government policy and regulation by considering the behavior of developers.     

Exfiltration in sanitary sewer systems in the US

Many municipalities throughout the US have sewer systems (separate and combined) that may experience exfiltration of untreated wastewater. A study was conducted by the US Environmental Protection Agency (USEPA) to focus on estimating the magnitude of leakage of sanitary and industrial wastewater from sewer pipes on a national basis. The method for estimating exfiltration amounts utilized groundwater table information to identify areas of the country where the hydraulic gradients of the wastewater are typically positive, i.e. the wastewater flow surface (within pipelines) is above the groundwater table. An examination of groundwater table elevations on a national basis reveals that the contiguous US comprises groundwater regions (established by the US Geological Survey) that are markedly different. Many parts of the northeastern, southeastern, and midwestern US have groundwater tables that are higher than the wastewater flow surface, resulting in inflow or infiltration. Conversely, the combination of a relatively low groundwater table and shallow sewer systems creates the potential for widespread exfiltration, a situation more commonly found in communities located in the western US.