城市燃气管网GIS系统的开发

随着我国天然气工业的不断发展，对于城市天然气管网的智能化管理已经作为一个全新的课题出现在燃气企业里。过去所使用的MIS系统（Management Information System），无论从效率、准确度、智能程度上讲，都已经不能满足目前城市燃气管网的精确管理。因此地理信息系统（Geography Information System，简称GIS系统）作为一种新的计算机管理系统应运而生，其主要特点是：有精确的管理、有标准的地图提供直接判断、空间关系与实物对应明确、管理直观。文章以企业对管理系统的需求以及技术可行性为出发点，阐述了GIS系统应具有的基本性能；同时结合燃气工程技术的发展，对燃气GIS系统做了应用开发研究；此外还对现阶段部分燃气GIS信息系统的不足做出了分析。     

VOD在有线电视网的实现

从视频点播系统的结构及组成和在有线电视网络中VOD系统的结构模式与应用两个方面，详细地阐述了如何利用有线电视网络实现视频点播，主要从以下3个方面介绍关于视频点播系统VOD技术：①视频点播VOD的技术原理；②视频点播系统的结构及组成；③有线电视视频点播系统的结构模式与应用。     

ADSL MODEM 远程管理方案浅析

阐述了ADSLMODEM远程管理的意义及应遵循的原则，并对远程管理的方案作了简要阐述，最后比较分析了不同方案的优缺点。     

The Challenge of the Market

Identifying markets for new or improved products for minor crops threatened with extinction is one critical component of any strategy intended to enhance prospects for sustainable production and use. Typically, however, activities linked to the sustainability of these commodities avoid addressing questions associated with assessing their commercial potential. After a brief review of this avoidance syndrome, this article presents a sample of practical, low-cost procedures to help evaluate the market prospects and procedures for crops like quinoa, while citing references to other methodological materials covering similar topics.     

圆杆弹性和弹—塑性扭转公式的探讨

对圆杆在线弹性阶段，弹－塑性阶段和全塑性阶段的扭转剪应力的计算公式作了分析，并推导了在材料的应力－应变关系（τ－γ关系）不服从虎克定律时，扭转真实剪应力的计算公式。文中对扭转强度计算公式的来源，物理含义及其都作了详细的说明。这对执行和理解国家ＧＢ１０１２８－８８《金属室温扭转试验方法》是有益的，而且对高校中材料力学的教学具有一定的参考价值。     

Demand elasticities in OECD: Dynamical aspects

Four models with different lag structures are used to express final energy demand in OECD from 1960–1982 as a function of real GDP and average energy price. The income and long-run price elasticities are not significantly dependent on the model specification, but the Koyck lag scheme, estimated in its distributed lag form, is found to give the most satisfactory results. The statistical properties of the data together with evidence of trends in the elasticities both suggest that the period of falling real prices prior to 1971 is not comparable to the present period. For the period after 1971, an income elsticity of 1.02 and a long-run price elasticity of -0.37 are obtained.     

Decentralized energy supply: Suitability for the UK's industrial sectors

From the results reported here it is suggested that policy decisions about the potential contribution of decentralized energy supply systems to UK industrial energy requirements should be based on the suitability of individual sectors rather than averaged over all sectors. The suitability of decentralized energy sources is evaluated, based on a themodynamic match between source and demand. This suitability criterion is used to identify the most appropriate sector in manufacturing industries for the adoption of decentralized energy supply, leaving aside economic cost considerations and individual site requirements.     

吉林省中部地区水资源配置初探

中部地区水资源总量为39.61亿m3。城市用水与农业、生态用水矛盾突出,城市供水能力不足,水污染问题严重,地下水超采严重,水资源开发利用不协调。该区水资源已无进一步开发利用的潜力,需通过调水工程解决缺水问题。水资源配置思路为从地处松花江上游的丰满水库引水,增加供水能力。     

基于生态水深-流速法的河段生态需水量计算方法

在界定了生态流速和生态水深概念的基础上，提出了一种同时考虑河道本身参数(湿 周、糙率、水力坡度)和维持某一生态功能所需河流流量的水力学方法，避免了湿周法不能反映复式断面真实水位流量关系的缺点，并用于验证黄河上游小川河段生态需水量，同时用Tennant法作了对比。结果表明：用生态水深-流速法得到的小川河段生态流量优于Tennant法所计算的生态需水量，由于该方法考虑了生态流速和生态水深，故所得的结果符合实际情况。     

Testing viability of cross subsidy using time-variant price elasticities of industrial demand for electricity: Indian experience

Indian electric tariffs are characterized by very high rates for industrial and commercial classes to permit subsidized electric consumption by residential and agricultural customers. We investigate the viability of this policy using monthly data for 1997–2003 on electric consumption by a few large industrial customers under the aegis of a small distribution company in the state of Uttar Pradesh. For a given price/cost ratio, it can be shown that if the cross-subsidizing class’ electricity demand is sufficiently elastic, increasing the class’ rates fail to recover incremental cross-subsidy necessary to support additional revenues for subsidized classes. This suboptimality is tested by individually estimating time-variant price-elasticities of demand for these industrial customers using Box-Cox and linear regressions. We find that at least for some of these customers, cross-subsidy was suboptimal prior to as late as October 2001, when rates were changed following reforms.