大同矿区综放开采覆岩压力拱演化规律研究

为研究大同矿区综放开采的覆岩运动特征,以同忻矿8105工作面为研究对象,运用关键层理论确定了同忻矿8105工作面关键层分布,采用理论分析、相似材料模拟方法对压力拱的演化规律进行了研究,并结合现场监测数据对研究结果进行了验证。结果表明,在同忻矿双系煤层开采条件下,关键层破断影响着压力拱的发展高度,沿工作面推进方向,压力拱的失稳步距为283~330 m。拱脚位置在工作面前方40~55 m,压力拱承载着大部分的覆岩载荷,一旦发生失稳破坏,会造成石炭系岩层与侏罗系采空区连通,引起工作面强矿压显现。     

中国交通运输碳排放时空演变及差异分析

核算了2003—2012年间中国30个省域的交通运输碳排放量和碳排放强度,分析了交通运输碳排放时空演变规律,分别计算了中国东、中、西部的交通运输碳排放量和碳排放强度的标准差和变异系数以定量分析其差异.结果表明:2003—2012年10年间,中国30个省域交通运输碳排放量呈逐年增长趋势,并整体呈现"西低东高"的特征,其中,湖北、广东和山东三省的总量居前3位,而内蒙古、吉林和重庆这3个省份(直辖市)的增速最快;交通运输碳排放强度整体上全国呈增长趋势,呈现出"西高东低"的非均衡变化特征;交通运输碳排放强度绝对差异增速趋缓,自2008年后三大区域的标准差和变异系数都呈现明显趋同效应.     

海河流域河流空间分布特征及演变趋势

海河流域涵盖我国"京津冀"经济圈,河流对流域内人类生存和经济发展具有重要支撑作用,研究河流空间分布及演变趋势对于合理利用河流水资源、保护河流生态和实现经济可持续发展具有重要意义.本文运用遥感资料的GIS分析方法,对海河流域的河流地貌、水系结构、河流曲率和河网密度、闸坝等指标进行分析,发现:1海河流域河流地貌划分为上游山区段、中部平原段和下游滨海段,3个区段水系形状依次为树枝状(受人为干扰小),编织状(中度人为干扰),稀疏编织状(人为干扰强烈);2流域水库和水闸修建阻断河流纵向连续性,五大水系(滦河、北三河、永定河、大清河、子牙河)连续性指标值低于5;320世纪60年代—80年代—2000年,流域河流平均曲率不断减小,河网密度呈现不定向波动,反映出人为控制对河道形态改变程度大.今后应减少人类活动对河流自然属性的改变,河流治理和修复过程中应充分考虑保护和改造河流地貌、水系结构、河流曲率和河网密度.     

雅鲁藏布江径流变化的影响因素分析研究

雅鲁藏布江流域作为西藏最重要的经济区,对全球气候变化极其敏感和脆弱.文章选择雅鲁藏布江流域作为研究区,通过对气候因素、径流变化的时空规律的分析,探讨了降水、气温等气候因子对径流的影响.得出:流域1960年-2009年年平均气温具有显著的上升趋势,升温趋势随海拔升高而增大的特点,流域1960年-2009年流域年降水呈上升的趋势,但趋势不显著,流域降水变化呈现复杂性.气温、降水的变化是影响雅鲁藏布江天然径流变化最直接的影响因素.     

产业共生网络演化研究进展

产业共生网络是通过物料、能源或信息等的传递所形成的企业间复杂的合作共生关系网络。由于受各种内外部因素的影响,产业共生网络一直处于不断发展演变中。研究产业共生网络演化,对破解工业园区资源与环境瓶颈、推动园区可持续发展具有重要的意义。我国工业园区经过数十年的快速发展,已初步形成了基于园区尺度的产业共生网络。本文对产业共生网络的形成及发展现状进行总结,分析了产业共生网络演化的驱动力及影响因素,并对现有的产业共生网络研究方法进行综述,对比与评价了不同建模方法的建模思路及优劣势。基于此,提出了未来研究与实践中需要突破的关键问题,建议继续拓展产业共生的研究范围,加强对产业共生网络演化仿真及可持续性评估的研究,从而为工业园区规划与管理提供可预测的、量化的指导工具。     

The effect of orifice plates with different shapes on explosion propagation of premixed methane–air in a semi-confined pipeline

The effect of internal shape of obstacles on the deflagration of premixed methane–air (concentration of 10%) was experimentally investigated in a semi-confined steel pipeline (with a square cross section size of 80 mm × 80 mm and 4 m long). The obstacles used in this study were circular, square, triangular and gear-shaped (4-teeth, 6-teeth and 8-teeth) orifice plates with a blockage ratio of 75%, and the perimeter of the orifice was regarded as a criterion for determining the sharpness of the orifice plate. The overpressure history, flame intensity histories, flame front propagation speed, maximum flame intensity and peak explosion overpressure were analyzed. The explosion in the pipeline can be divided into two stages: initial explosion and secondary explosion. The secondary explosion is caused by recoiled flame. The perimeter is positively related to the intensity of the recoiled flame and the ability of orifice plate to suppress the explosion propagation. In addition, the increase in the perimeter will cause the acceleration of the flame passing through the orifice plate, while after the perimeter of the orifice reaches a certain value, the effect of the increase in perimeter on explosion excitation becomes no obvious. The overpressure (static pressure) downstream of the orifice plate is the result of the combined effect of explosion intensity and turbulence. The increase in perimeter leads to the increase in turbulence downstream of the orifice plate which in turn causes more explosion pressure to be converted into dynamic pressure.     

A preliminary explore to the forced ventilation on the toxic gas release/dispersion and the hazard mitigation within a petrochemical plant

More than thirty-five years ago, the Bhopal disaster shook the whole world and investigators found out that many people survived just because they turned on the fans in their bedrooms. It was postulated that the forced ventilation played an important role in diluting the toxic gas and saved these people. In order to provide evidence to solve this old mystery, this research employed FLACS software to assess the hazardous degree of a toxic gas (hydrogen sulfide) leakage within a petrochemical process. Series of gas dispersion simulations were performed to actualize the hazardous characteristics and the corresponding risks of the release accident. The study shows that the hazardous level and the hazard range can be greatly influenced when parameters, such as the gas leakage circumstances (atmospheric conditions and wind speed) and the mitigation measures (direction of fans and their speed) are altered.By using explosion-proof fans in different positions and ventilation directions, combined with the natural wind in a certain direction, this research attempts to detect the best combination from various mitigation designs and to compare the influence of fan directions on hazard mitigation. It is also the first time of its kind to simulate the effect of forced ventilation on hazard mitigation within a process plant. The results show that the hazardous level of a toxic release can be effectively alleviated, when the direction of the mechanical ventilation is against the natural wind direction. With the help of the CFD simulation and the quantitative risk analysis technique, different loss prevention strategies can be tested via this method in order to establish a safer working environment.     

Assessing the influence of real releases on explosions: Selected results from large-scale experiments

The research activities in the project Assessing the Influence of Real Releases on Explosions (AIRRE) included a unique series of large-scale explosion experiments with high-momentum jet releases directed into congested geometries with subsequent ignition. The primary objective for the AIRRE project was to gain improved understanding of the effect that realistic releases and turbulent flow conditions have on the consequences of accidental gas explosions in the petroleum industry. A secondary objective was to develop a methodology that can facilitate safe and optimal design of process facilities. This paper presents selected results from experiments involving ignition of a highly turbulent gas cloud, generated by a large-scale, pressurised release of natural gas. The paper gives an overview of the effect on maximum explosion overpressures of varying the ignition position relative to the release point of the jet and a congested region placed inside the flammable cloud, with either a high or a medium level of congestion. For two of the tests, involving a jet release and the medium congestion rig, the maximum overpressures significantly exceeded those obtained in a quiescent reference test. The paper presents detailed results for selected tests and discusses the effect of the initial flow field generated by realistic releases – including turbulence, net flow and concentration gradients – on relevant explosion phenomena.     

不同应力比的循环荷载下砂岩变形损伤特性研究*

为探究循环荷载下砂岩试件的变形损伤特性,开展3种不同幅值下的循环加卸载试验,分析应力比对砂岩变形损伤与能量耗散特性的影响规律。结果表明:应力比越大,相邻加载段应变差越大,部分高应力下不可恢复的变形在低应力时有所恢复;当应力比为0.50和0.67时,各循环泊松比相差不大,介于0.231~0.247之间,而当应力比为0.88时,泊松比随循环数有增加趋势;应力比越大耗散能占比越大,试件吸收并转化为用于自身损伤的能量越大。高应力循环荷载下试件损伤逐渐积累,在衡量试件损伤变化时采用的耗散能只考虑了轴向残余应变与应力,忽略了径向变形的影响。     

The asymmetric scent: ringtailed lemurs (<Emphasis Type="Italic">Lemur catta</Emphasis>) have distinct chemical signatures in left and right brachial glands

Distinctive cues are predicted to evolve when the benefits obtained by the recognition process overcome its costs. When individual recognition is particularly beneficial for both senders and receivers, the expression of strongly distinctive signals is predicted to evolve. On the other hand, it could be predicted that each individual should show a very stable individual signature. In the same perspective, a great stability of the individual signatures could be expected. Lemur catta is the first non-human primate in which olfactory individual recognition has been demonstrated on the basis of the specialized brachial gland secretions. In this paper, I performed gas chromatograph analyses of right and left gland samples collected in two different periods (breeding and non-breeding seasons) from seven males. The aim was to verify if a diversification in such cues, already demonstrated at the inter-individual level, also occurs at the intra-individual level between left and right glands. I verified, by discriminant analysis and chemical distance comparisons, that each gland of each lemur has its particular signature that is maintained through time. Moreover, such diversification resulted so marked to make the overall intra-individual chemical differences similar to/as strong as the inter-individual ones. Since in rodents several odors from different glands may be integrated in individual recognition, I suggest that bilateral diversification in L. catta scents may offer an enhanced distinctiveness that could provide benefits in mate choice and social relationships.