成庄矿瓦斯综合治理措施探讨

针对成庄矿煤层瓦斯含量高并有煤与瓦斯突出危险性的问题,实施了地面煤层气井抽放、井下区域性预抽、通风系统优化改造和提升瓦斯抽采系统能力等综合治理措施,应用结果表明,成庄矿2004-2010年,在绝对瓦斯涌出量增大了78.11％、相对瓦斯涌出量增大了27.74％的情况下,风排瓦斯量仅增大了6.35％,抽采瓦斯量增大了197.05％,大幅度降低瓦斯事故发生概率的同时瓦斯抽采效果显著提高.     

Fabrication of Densely Packed AlN Nanowires by a Chemical Conversion of Al2O3 Nanowires Based on Porous Anodic Alumina Film

Porous alumina film on aluminum with gel-like pore wall was prepared by a two-step anodization of aluminum, and the corresponding gel-like porous film was etched in diluted NaOH solution to produce alumina nanowires in the form of densely packed alignment. The resultant alumina nanowires were reacted with NH₃ and evaporated aluminum at an elevated temperature to be converted into densely packed aluminum nitride (AlN) nanowires. The AlN nanowires have a diameter of 15–20 nm larger than that of the alumina nanowires due to the supplement of the additional evaporated aluminum. The results suggest that it might be possible to prepare other aluminum compound nanowires through similar process.     

Manganese-based catalyst for NO removal at low temperatures: thermodynamics analysis and experimental validation

Abstract

Selective catalytic reduction of nitrogen oxides with loaded urea is a novel method for removing NO under excess oxygen and low temperature conditions. In present work, a comprehensive thermodynamic study for NO removal is executed based on the Gibbs free energy change. This research mainly includes the detailed analyses of NO removal mechanism, the feasibility analyses for manganese as the active element and the experimental study for synthesized manganese-based catalyst (preparation, characterization and performance test). The catalyst in present study can reach 82% NO conversion and near 98% N₂ selectivity at 50?°C, which validates the correctness of the thermodynamic calculations.     

Mechanism behind the Size Effect Phenomenon

Size effect (SE) on quasi-brittle fracture of concrete and concretelike heterogeneous materials has been commonly demonstrated by the influence of specimen size D on the transition from strength-dominant fracture to toughness-dominant fracture for geometrically similar specimens with a common initial-crack/specimen-size ratio, i.e., a0/D = constant. Under such a condition, size D appears to be the single controlling parameter for SE. In this study, we clarify that the primary source of quasi-brittle fracture, the presence of a large fracture process zone (FPZ) in front of a crack-tip, does not follow the condition of geometry similarity even for geometrically similar specimens. This suggests that the role of FPZ is not clearly explained for SE. Therefore, this study emphasizes the interaction between FPZ and the nearest specimen/structure boundary, and the consequent SE phenomenon. The deficiencies associated with the common SE models developed by Bazant and his coworkers are discussed through comparisons with the analysis on the boundary and FPZ interaction, or the boundary effect. It is shown that quasi-brittle fracture and the transition from strength-dominant fracture to toughness-dominant fracture can occur even if specimen/structure size D is constant, i.e., size D is not the dominant factor for SE.     

Study on multi‐objective optimization of load dispatch including renewable energy and CCS technologies

This paper mainly studies the multi‐objective optimization of load dispatch of power systems including renewable energy and CO₂ capture and storage (CCS) technologies. The improved environmental/economic load dispatch model for the power system is constructed, considering the renewable energy utilization and CCS technologies. A novel singular weighted method (SWM) has been proposed in this paper for solving this kind of multi‐objective and multi‐constraint optimization problem. A power system with five generators has been applied in one case study to test the model and SWM. It was concluded that the share that each unit takes is not linear; however, the optimal results are largely relevant to the characteristics of the units. In addition, the research results showed that with the increment of the weight coefficient for a certain objective function, the optimization result was closer to the single optimization result for that objective function; and with the increase of forecast demand load, a 35 MW wind energy unit and a 200 MW water energy unit should be built. Copyright © 2009 John Wiley & Sons, Ltd.     

Improved ant colony optimization algorithms for determining project critical paths

In project management, a project can be represented as a network in two ways; namely, activity-on-arc (AoA) and activity-on-node (AoN). Two recent papers have shown that ant colony optimization (ACO) could find critical path(s) in projects represented as AoA networks. This paper points out that the number and placement of logical dummy activities associated with AoA-based networks can pose serious problems. To get around the problems, an ACO technique based on AoN networks is then proposed. For comparison, the two existing AoA-based ACO algorithms were reproduced and modified into AoN-based algorithms. Moreover, the proposed ACO algorithm was applied to AoA networks as well. All six algorithms were tested with several benchmark problems. The test results strongly indicate that AoN-based ACO algorithms are more effective and efficient in finding critical paths than AoA-based algorithms.     

提高乡镇企业铸件品质的途径

乡镇企业铸造厂应结合自身情况，按ISO9000标准，建立科学管理体系；逐步完善检测手段；积极地采用新技术、新工艺；走专业化、规模化、集约化及清洁化的道路，以提高铸件的品质和经济效益。     

岩石、混凝土类材料复合裂纹断裂准则的探讨

本文对岩石与混凝土类脆性材料的强度和断裂机理进行了简要分析。在最大分离位移(MAXSD)屈服准则的基础上,建立了三维复合型裂纹的断裂准则。并与混凝土材料的三维复合裂纹和Ⅰ、Ⅱ型复合裂纹的断裂试验结果进行了比较。     

连续体形状优化中的几何表示及其敏度分析的研究

基于 B 样条函数与设计元概念,本文提出了连续体形状优化中颇为重要的几何描述法,并进而导出了所有的敏度计算公式.