Study on splitting failure in rock masses by simulation test,site monitoring and energy model

To study the phenomenon of splitting failure in the rock mass adjacent to an underground hydro-power station excavation in a region of high initial stresses, both laboratory simulation tests and site monitoring were undertaken. Concurrent with the excavation design and monitoring, an energy dissipation model was formulated. Back analysis was performed on the monitored site data obtained during excavation and construction. For study in the laboratory, large specimens were designed using rock-like materials. Using a true triaxial state test condition, one side of the specimen was unloaded to model the exposed cavern wall of the excavation. In the experimental model, rock splitting failure was observed. During the excavation (construction site), monitoring instruments were installed in boreholes in the cavern wall. Sliding micrometer, electrical resistivity tomography equipment and a borehole TV camera were employed to monitor the effects of the excavation. Back analysis using the deformation of the surrounding rock mass was carried out. The deformation and the depth of the splitting area in the surrounding rock mass after final excavation were predicted using the energy dissipation model and also by an alternate prediction formula for the splitting depth previously proposed by the authors. The correlation of measurements and predicted results was reasonably good.     

Immigration and Construction: The Makeup of the Workforce in the Washington, D.C., Metropolitan Area

There are an estimated 11 million illegal immigrants currently residing in the United States. Of this population, research shows that approximately 19% work in the construction industry, comprising around 14% of all construction workforces. The Washington, D.C. metropolitan region has a unique makeup of workforces within the construction industry. Between September 2006 and February 2007, 896 construction workers from several projects in the Washington, D.C. metropolitan area participated in a survey. The study targeted the low-skilled, immigrant-saturated trades in construction. The most compelling finding in this study was that illegal immigrants make up a far greater proportion of the construction workers in low-skilled trades than indicated by national averages, 55% as compared to between 20 and 36% nationally. This will increase the impact of immigration and immigration reform substantially for the Washington, D.C. metropolitan.     

Environomic multi-objective optimisation of a district heating network considering centralized and decentralized heat pumps

Concern for the environment has been steadily growing in recent years, and it is becoming more common to include environmental impact and pollution costs in the design problem along with construction, investment and operating costs.     

耐酸性混凝土在弱酸性地基中的工程应用

针对重庆江北区建新西路三期工程（天原段）建设中所遇到的弱酸性地基处理难题，通过试验研究和工程检测，选择配制耐弱酸性混凝土的地方材质，对耐弱酸性混凝土进行试配和优化，确定设计配合比，使所配制的耐弱酸混凝土具有良好的性能，满足工程的需要，为重庆市弱酸性地基环境中耐酸混凝土施工应用探索出了一条新路。     

The role of district heating in future renewable energy systems

Based on the case of Denmark, this paper analyses the role of district heating in future Renewable Energy Systems. At present, the share of renewable energy is coming close to 20 per cent. From such point of departure, the paper defines a scenario framework in which the Danish system is converted to 100 per cent Renewable Energy Sources (RES) in the year 2060 including reductions in space heating demands by 75 per cent. By use of a detailed energy system analysis of the complete national energy system, the consequences in relation to fuel demand, CO₂ emissions and cost are calculated for various heating options, including district heating as well as individual heat pumps and micro CHPs (Combined Heat and Power). The study includes almost 25 per cent of the Danish building stock, namely those buildings which have individual gas or oil boilers today and could be substituted by district heating or a more efficient individual heat source. In such overall perspective, the best solution will be to combine a gradual expansion of district heating with individual heat pumps in the remaining houses. Such conclusion is valid in the present systems, which are mainly based on fossil fuels, as well as in a potential future system based 100 per cent on renewable energy.     

Increased use of district heating in industrial processes – Impacts on heat load duration

Current knowledge of the potential for an increased use of industrial district heating (DH) due to conversions of industrial processes to DH is limited. In this paper, a Method for Heat Load Analysis (MeHLA) for exploring industrial DH conversions has been developed. This method can be a helpful tool for analyzing the impact different industrial processes have on the local DH system, when processes that utilize electricity and other fuels, convert to utilizing DH. Heat loads for different types of industries and processes are analyzed according to characteristics such as temperature levels and time-dependency. MeHLA has been used to analyze 34 Swedish industries and the method demonstrates how conversion of industrial processes to DH can result in heat load duration curves that are less outdoor temperature-dependent and more evenly distributed over the year. An evenly distributed heat load curve can result in increased annual operating time for base load DH plants such as cogeneration plants, leading to increased electricity generation. In addition to the positive effects for the DH load duration curve, the conversions to DH can also lead to an 11% reduction in the use of electricity, a 40% reduction in the use of fossil fuels and a total energy end-use saving of 6% in the studied industries. Converting the industrial processes to DH will also lead to a potential reduction of the global carbon dioxide emissions by 112,000 tonnes per year.     

Field investigation on consumer behavior and hydraulic performance of a district heating system in Tianjin,China

With the implementation of heat reforms in China, the application of thermostatic radiator valves (TRVs) has been gaining popularity in the new-style district heating systems (DHSs). The objective of this study was to investigate consumer behavior (including regulation of TRVs and opening of windows) and its influences on the hydraulic performance and energy consumption of individuals and the whole system. The concurrence rate of individual behaviors and hydraulic interactions between individuals were analyzed. This study should be helpful to gain a comprehensive understanding of the new DHSs in China and consider a proper design/control strategy for these systems.     

The effect of proposed district centres on Melbourne's central business district

Abstract

Concerns have been expressed that the designation of the 14 district centres in the MMBW's proposed Amendment 150 will have an adverse effect on the Central Business District. This paper analyses these claims and contends that there is little threat from the district centres themselves. Because the planning concepts espoused in Amendment 150 and the Melbourne LDS are not sufficiently related to the economic development processes occurring in the city, they will have limited success in other than physical enhancement terms. The opportunity to develop an alternative economic role for the CBD has been overlooked.     

人-机参与公交客运枢纽选址方法

提出了一种城市客运枢纽选址方法——人-机参与枢纽选址法,并以北京市公交系统为研究对象,应用该方法进行城市客运枢纽选址试算。该方法分为两部分,确定性选址与非确定性选址,前者主要依据城市总体规划以及有关专家的综合分析确定枢纽地址;后者主要依据有关的基础资料,经计算机进行有关指标的计算,进行定量遗址,然后根据计算结果并参照其它制约条件,进行综合性决策,做出最终的城市客运枢纽的选址布局。