群决策在房屋结构可靠性评估中的应用

阐述了砌体结构房屋可靠性评估中，各影响因素权重的确定是重要而困难的问题。基于层次分析的群决策确定各因素权重分配时，可有效地减少人为因素的影响，从而使权重确定结果更加客观、科学、合理。     

Decision modeling and acceptance criteria

This paper is partly tutorial by presenting well known classical decision theory in a slightly untraditional form, but it does also present thinking and results that have not been published in the engineering literature before. The paper introduces the mathematical modeling basis for rational formulation of decision criteria and public acceptance criteria connected to risk analysis of technical operations that may endanger human life and property. Public restrictions on the decisions concerning the design, construction and managing of the technical operation have in the past been imposed on the basis of the frequency and severity of experienced adverse events. No clear rationale to decide how restrictive the public should be in setting a boundary for allowable risk seems to have been applied. To clarify this problem, focus is on the difficulty of simultaneously having two decision makers, the owner that tries to optimize the net gain of the operation, and the public that has somewhat different preferences than the owner, but also strong interests in the success of the owner. The principles of rational decision are needed for appreciation of the problem. Recognizing that there is an insurance compensation value of a human life and a public money equivalent of a human life, where the last value usually is considerably larger than the first value, it is possible from the decision analysis to determine an upper limit that the public should impose on the ratio of the owner's expected loss rate to the expected gain rate. The public money equivalent of a human life is assessed by use of a recently in (Nathwani JS, Lind NC, Pandey MD. Affordable safety by choice: the life quality method. Waterloo, Ontario, Canada: Institute for risk Research, University of Waterloo, 1997) suggested Life Quality Index (LQI) that combines wealth in terms of Gross Domestic Product per person, life expectancy at birth, and yearly work time into a single number. The philosophy behind the published evaluations is that the prevention of a loss of a life is counteracted by a cost such that the LQI remains unchanged (Skjong R, Ronold K. Societal indicators and risk acceptance. In: 17th International Conference on Offshore Mechanics and Arctic Engineering, number OMAE98-1488. ASME; 1998; Rackwitz R. Optimization and risk acceptability based on the Life Quality Index. Structural Safety 2002;24:297–331.).     

Comparative analysis and performance of load bearing characteristics of biogas and gasoline-fuelled electric generator

ABSTRACT

This research demonstrates a simplified purification of biogas from hybrid waste and conversion of a single cylinder spark ignition engine to use biogas. The scrubbed gas obtained showed 95% methane enriched biogas. The carburettor of the gasoline engine was modified with a tri-fuel carburettor to suit the input specimen fuel fed to the modified 2.5 kVA, 230 V, and 50 Hz reciprocating engine to generate power. Results showed that 1 kg of compressed biogas ran for 46 min with a load capacity of 1800 W on the 2.5 kVA modified generator, while a litre of gasoline ran for 72 min under the same loading capacity. A comparative assessment of the load bearing characteristics was conducted. Load condition exceeding 1000 W resulted in a voltage output drop of 14.25% on biogas while a small change in voltage of 0.06% occurred for loading conditions between 100 and 1000 W. There was 8.5% decrease in engine speed while operating on biogas with little or no change on gasoline. Maximum torque of 5 and 3.5 Nm at 1800 W electric loading was experienced for gasoline and biogas. Finally, the BSFC for gasoline and biogas at 15% loading condition was maximum at 2000 and 2400 kg/kWh, respectively.     

A fuzzy approach for the earned value management

The Earned Value technique is a crucial technique in analyzing and controlling the performance of a project which allows a more accurate measurement of both the performance and the progress of a project. This paper presents a new fuzzy-based earned value model with the advantage of developing and analyzing the earned value indices, and the time and the cost estimates at completion under uncertainty. As the uncertainty is inherent in real-life activities, the developed model is very useful in evaluating the progress of a project where uncertainty arises. A small example illustrates how the new model can be implemented in reality.     

Benefit evaluation for off‐site production in construction

Evaluating to what extent a component or building system should be produced off‐site is inadequate within the industry. The potential benefits of off‐site production (OSP) are commonly cited when justifying an OSP approach, yet holistic and methodical assessments of the applicability and overall benefit of these solutions, to a particular project, have been found to be deficient. Common methods of evaluation simply take material, labour and transportation costs into account when comparing various options, often disregarding other cost‐related items such as site facilities, crane use and rectification of works. These cost factors are usually buried within the nebulous preliminaries figure, with little reference to the building approach taken. Further, softer issues such as health and safety, effects on management and process benefits are either implicit or disregarded within these comparison exercises. Yet it is demonstrated that these issues are some of the most significant benefits of OSP. A series of case studies demonstrated that evaluation focus is almost solely on direct material and labour costs of components, without explicit regard for the wider cost or soft issue implications of OSP on a project. The paper argues that until evaluation is more holistic and value‐based rather than cost‐based, OSP uptake in construction will be slow.     

Making client values explicit in value management workshops

Value management is a project‐focused process that makes explicit and appraises the functional benefits of a product, process or service consistent with a value system determined by the client. The value system of the client necessarily requires a method for value setting using harder performance variables than the commonly described facets of time, cost and quality. Current value theory is critically appraised in the context of current value management practice. The research proposition is that the constituent parts of time, cost and quality can be made overt enabling a client to express satisfaction in terms of a finite number of variables enabling the explicit statement of client value within a value management workshop. An action research study into the discovery of the component parts of the client's value system at the early stages of construction projects concludes that the variables are the nine non‐correlated, high order, discretionary performance variables of capital expenditure, operational expenditure, time, esteem, environment, exchange, politics/community, flexibility and comfort.     

冻融循环对烧结砖回弹值影响的试验研究

回弹法检测砖强度虽然简便、快捷,但对既有建筑砌体中的砖检测是否适用?通过冻融试验加快砖的"老化",由此对回弹法的适用性进行了探索性研究,并提出了相关建议。     

刍议新时期大学教学管理的价值取向

教学管理改革是高等学校教育教学改革的重要内容,对于高等学校提高人才培养水平和办学质量具有重大意义。大学教学管理价值取向的基本内涵及其在提高大学教学管理质量和效率方面的重要性,归纳出在国家经济体制实现重大变革、高等教育进入大众化的新时期,大学教学管理应该具备的价值取向。新的价值取向包括尊重学术权力、尊重师生自由发展、重视服务、尊重民主法治、注重公平、重视节能环保。     

Recursive State-space Model Identification of Non-uniformly Sampled Systems Using Singular Value Decomposition☆

In this paper a recursive state-space model identification method is proposed for non-uniformly sampled systems in industrial applications. Two cases for measuring all states and only output(s) of such...     

钠基膨润土胶质价测试方法的改进

以两种人工钠化膨润土为研究对象,探讨了文献胶质价测试方法的不合理性、取土量和MgO量这两个关键因素。实验结果表明:用常规100 mL量筒测胶质价时,取土量和MgO量影响较大,有必要针对具体试样做条件试验,最佳条件是1#钠土为取3.00 g土、0.2 g MgO,2#钠土为取5.00 g土、0.33 g MgO。