A new leak location method based on leakage acoustic waves for oil and gas pipelines

In order to study a new leak detection and location method for oil and natural gas pipelines based on acoustic waves, the propagation model is established and modified. Firstly, the propagation law in theory is obtained by analyzing the damping impact factors which cause the attenuation. Then, the dominant-energy frequency bands of leakage acoustic waves are obtained through experiments by wavelet transform analysis. Thirdly, the actual propagation model is modified by the correction factor based on the dominant-energy frequency bands. Then a new leak detection and location method is proposed based on the propagation law which is validated by the experiments for oil pipelines. Finally, the conclusions and the method are applied to the gas pipelines in experiments. The results indicate: the modified propagation model can be established by the experimental method; the new leak location method is effective and can be applied to both oil and gas pipelines and it has advantages over the traditional location method based on the velocity and the time difference. Conclusions can be drawn that the new leak detection and location method can effectively and accurately detect and locate the leakages in oil and natural gas pipelines.     

Ecological Risk Assessment of Abandoned Shrimp Ponds in Southern Thailand

The potential ecological risks associated with contaminants from 15 abandoned shrimp ponds in southern Thailand were assessed at the screening level. Shrimp ponds reported as out of production for more than 2 years were selected as sampling sites. The assessment endpoint was identified as the protection of aquatic life from hazard of multiple agents or stressors in water or sediment from the ponds. The measurement endpoints were amount of toxic phytoplankton species, Yellow Head Viruses, SEMB viruses, oxytetracycline, cadmium, copper, and manganese. Data from field measurements and laboratory analyses obtained primarily from April to June 2003 were used in the risk analysis. The results showed that insignificant amounts of stressors were present, except for the metals. So, only concentration values of the metals were used in the calculation of hazard quotients (HQ) for risk characterization. The highest potential ecological risk characterized by the highest HQ value observed for each metal was 19 for manganese, 4.3 for cadmium, and 1.8 for copper. These findings indicated a need for further ecological risk assessment at a more detailed level to focus on the bioavailability and effects of metals from abandoned shrimp farms, with manganese the highest priority.     

论高等学校班主任和辅导员工作的定位

本文强调工作定位的重要性,对高等学校班主任和辅导员等学生工作者的定位进行了分析,指出:高等学校的班主任和辅导员既是第一线的教师,又是第一线的管理干部,是集"高校教师"和"高校管理干部"双重身份于一体的教育工作者,思想政治工作者,大学生日常行为的管理者,大学生成才与发展的服务者。     

基于主逻辑图的安全风险建模研究

概率风险评估已成为研究复杂系统安全风险较为成熟的方法 ,其风险模型的建立是基于故障树/事件树的 ,风险分析具有众多的静态特性。然而 ,大的复杂系统往往存在诸多动态因素 ,在风险研究需要考虑这些动态因素的情况下 ,基于传统故障树 /事件树的模型则难以提供支持。笔者对此进行了分析 ,提出了基于主逻辑图的安全风险建模 ;主要介绍了主逻辑图的概念及其建模方法 ,并对模型进行了分析 ;在此基础上 ,基于主逻辑图分析事故场景 ,对场景风险的量化评估进行了简要介绍 ,并结合某核反应堆例子进行了分析。     

复杂矿井通风系统角联风路自动识别方法的研究

角联风路的识别与稳定性分析是矿井通风系统稳定性与可靠性分析理论中的核心内容之一。笔者对通风系统角联风路进行了深入的研究;分析了通路法的局限性,简化了角联风路的数学模型,提出了快速、准确、灵活的角联风路自动识别的新方法——节点位置法;编写了角联风路自动识别软件,并应用现场数据进行测试,将其结果与通路法的结果进行了比较分析;证明了节点位置法是切实可行的。     

河流水质自动监测站选址适宜性评价

为建立和量化适于河流水质自动监测站选址的评价方法体系,提出了河流水质自动监测站选址一致性、可行性和适宜性评价问题,并建立了选址可行性和适宜性评价2套指标体系。以自动站选址与手工断面位置不一致为前提,利用累乘指数判断选址可行性,在可行的基础上利用模糊综合评价进一步分析选址的适宜性。应用案例显示,罗汉大桥断面水质自动站选址于手工断面下游150 m处是可行的,并且此选址高度适宜,在具有水质代表性的同时兼顾成本和运维管理需求。     

基于专利的区域环境技术创新水平空间分异研究

以环境技术专利表征创新水平,采用绝对指标与相对指标、专利结构布局系数(或特化系数)与技术创新主体结构布局系数,衡量中国各省市环境技术创新水平的空间分异,探讨其不平衡性的原因.研究结果表明,绝对指标评价的环境技术创新水平,呈现"东高西低"的格局;相对指标表征的环境技术创新水平,大部分省市的评价结果基本上在0.1～0.5、0.59～1.04之间,空间分异不明显.东部地区省市发明专利、企业专利特化系数高,如天津、香港、北京、上海的发明专利特化系数均在1.3以上,香港和上海的企业专利特化系数大于2.但是发明专利、公司企业专利--2项最具价值的专利技术创新水平均较高的省市不多,我国环境技术创新水平整体水平不高.     

手机定位人口数据在应急救援中的应用

随着智能手机的普及,基于手机定位的人口数据在突发性灾害应急救援领域发挥着日益重要的作用.以近几年地震灾区为主要研究对象,选择灾区中有代表性的旅游景区、县城及乡镇,获取这些区域手机定位的人口数据,同时采用传统方法估算区域内人口数量,并进行差异性对比.研究结果表明:差异性最大的是旅游景区、其次是县城和乡镇;在人口年度变化上...     

Field released transgenic papaya effect on soil microbial communities and enzyme activities

Soil properties, microbial communities and enzyme activities were studied in soil amended with replicase （RP）-transgenic or non-transgenic papaya under field conditions. Compared with non-transgenic papaya, significant differences （P〈0.05） were observed in total nitrogen in soils grown with transgenic papaya. There were also significant differences （P〈0.05） in the total number of colony forming units （CFUs） of bacteria, actinomycetes and fungi between soils amended with RP-transgenic plants and non-transgenic plants. Compared with non-transgenic papaya, the total CFUs of bacteria, actinomycetes and fungi in soil with transgenic papaya increased by 0.43-1.1, 0.21-0.80 and 0.46-0.73 times respectively. Significantly higher （P〈0.05） CFUs of bacteria, actinomycetes and fungi resistant to kanamycin （Km） were obtained in soils with RP-transgenic papaya than those with non-transgenic papaya in all concentrations of Km. Higher resistance quotients for Km＇ （kanamycin resistant） bacteria, actinomycetes and fungi were found in soil planted with RP-transgenic papaya, and the resistance quotients for Km＇ bacteria, actinomycetes and fungi in soils with transgenic papaya increased 1.6-4.46, 0.63-2.5 and 0.75-2.30 times. RP-transgenic papaya and non-transgenic papaya produced significantly different enzyme activities in arylsulfatase （5.4-5.9x）, polyphenol oxidase （0.7-1.4x）, invertase （0.5-0.79x）, cellulase （0.23-0.35x） and phosphodiesterase （0.16-0.2x）. The former three soil enzymes appeared to be more sensitive to the transgenic papaya than the others, and could be useful parameters in assessing the effects of transgenic papaya. Transgenic papaya could alter soil chemical properties, enzyme activities and microbial communities.     

横通道通风对隧道火灾烟气蔓延影响的数值模拟研究

为探究隧道横通道通风对隧道火灾烟气蔓延的影响规律,使用火灾动力学模拟软件FDS,对不同火源位置的横通道临界风速、主隧道温度分布以及烟气层高度进行研究。研究结果表明：在一定火源功率范围内,隧道横通道临界风速与火源功率的1/3次方成正比且火源距横通道越远,临界风速越小;当火源位于交叉口,横通道使用临界风速通风时,隧道内烟气温度明显降低,烟气迅速沉降到2 m以下;当火源距离交叉口10,20 m,横通道通风会加快火源下游烟气沉降,烟气沉降速度随横通道通风速率的增大而增大;当火源位于交叉口时,烟气沉降由横通道通风对烟气的降温作用和涡旋作用共同主导,当火源位于距离交叉口10,20 m时,烟气沉降主要由涡旋作用主导。