综采工作面隔尘空气幕出口角度对隔尘效果的影响

综采工作面隔尘空气幕的出口角度是影响其隔尘效果的关键因素之一。利用Fluent计算流体力学软件,以河北金牛能源股份有限公司葛泉矿1528综采工作面为研究对象,对空气幕不同出口角度下综采工作面气流流场及空气幕两侧呼吸性粉尘浓度分布进行数值模拟,分析空气幕出口角度对其隔尘效果的影响。研究结果表明:适当调整空气幕出口角度,使气幕射流倾斜于产尘区,有利于提高空气幕的隔尘效果;并获得了阻止采煤机滚筒割煤时所产生的粉尘向司机工作区扩散的最佳空气幕出口角度,即出口角度在5°～10°范围,隔尘空气幕的工作效率较高,采煤机司机处的粉尘浓度最低,并通过现场试验对数值分析结果进行了验证。     

Dependence on forest resources and tropical deforestation in Ghana

In Ghana, forests provide many products on which the local population subsists. However, these resources are depleting due to a variety of factors including agricultural expansion and over-exploitation of forest resources. This paper presents an analysis of the level of local dependence on forest resources and its implications for forest management in Ghana. The paper also outlines the causes of continuing deforestation in the studied region from the perspective of the local residents and discusses what role they could play in addressing the problem. The aim is to share more light on the current causes of deforestation and make suggestions for improved community-based forest management practices that could help to reduce deforestation. Primary data was collected through personal interviews and focus group discussions with 431 household heads randomly selected from three Forest Districts in Ghana. The survey showed that income from agriculture constituted 60% of the average total rural household income. Forest income provided 38% of total household income, and off-farm income 2%. The four most highly ranked causes of deforestation are poverty-driven agriculture, lack of alternative rural wage employment other than farming, household population levels, and conflict in traditional land practices. This shows a shift in the view of local people who in the past were quick to blame logging companies and government policies for deforestation. The majority of the respondents depended on wild animals like snail, bush meat, wild honey and wild and cultivated vegetables. Given the reasons for deforestation, much thought needs to go into agroforestry practices (e.g. snail farming, bee keeping, fish farming, and vegetable production) in efforts to reduce deforestation, which are currently less promoted. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Occupational Safety Culture Index (OSCI)——measuring the community and employees awareness,attitude and knowledge towards workplace safety and health in Hong Kong SAR

Promoting occupational safety and health in Hong Kong,Special Administrative Region of China is an important and ongoing mission. As the major organization with statutory responsibilities,the Occupational Safety and Health Council understand the importance to strengthen and cultivate our safety culture. It is widely believed that numbers of occupational related diseases and injuries could be prevented with the improvement of the awareness and attitudes of the employees and the public. Therefore,a comprehensive and in-depth study to monitor the occupational health and safety level and status of the community and working population is needed. Objectives: Our Council has developed the Occupational Safety Culture Index ( OSCI) to measure the current level of community and workplace safety and health awareness,knowledge and attitude. Benchmarking measures of the key safety performance indicators are to be derived thereof. Methods: A territory-wide random telephone survey was conducted to assess the community and employees’awareness,attitude and knowledge in 2008. A structured questionnaire was designed with the content validity and reliability assessed before the survey administration. A series of quality control approaches were also applied to assure the quality of the fieldwork and the reliability of the data. Results: 1,531 eligible participants’data were collected and computed into 2 types of composite indices,Occupational Safety Culture Index ( Community) ( OSCIC) and Occupational Safety Culture Index (Workplace) (OSCIW) . With the maximum score of index at 100,the overall score of OSCIC is 66. 9 and the OSCIW is 61. 3 in Hong Kong. Achievements: OSCI served as an effective management tool to measure the safety culture in Hong Kong. With a representative sample and high quality study control and validated assessment approaches,the OSCI and the sub-indices are reliable indicators to assess the effectiveness of safety culture enhancement strategy and the OSH intervention measures.     

共同沟工艺及给排水设计的几点探讨

我国在工程设计中越来越多地采用共同沟工艺,但尚未有国家层面的标准化的相关规范,因此现阶段的工艺设计在给排水方面需参照国外及国内已兴建的共同管沟,尽可能全面地考虑工程设计中会碰到的问题,由此提出一些设计理念。     

以美国为鉴探讨中国参与公海保护区建设的对策建议

介绍了美国海洋保护区的主要管理模式和管理机构及相关法律与政策,建立公海保护区的立场和实践活动,提出了我国参与公海保护区建设的对策建议。     

鄱阳湖流域水葫芦(Eichhornia crassipes)对水体微塑料的吸附截留效应

微塑料是环境中的新型污染物,随着人们对微塑料污染的认识,微塑料在河流和湖泊等淡水湿地环境中的迁移问题受到普遍关注.中国内陆最大淡水湖鄱阳湖湿地受五河流域及其地表径流的影响,湿地水环境中的微塑料污染问题也不容忽视.为了解鄱阳湖各流域水体中微塑料的分布现状及水生植物对微塑料的吸附截留效应,选择鄱阳湖流域的赣江、信江、抚河、修水和饶河这五河水系入湖段为研究区,以各流域水体及其普遍存在的漂浮植物水葫芦（Eichhornia crassipes）为研究对象,分析鄱阳湖五河流域水葫芦对水体微塑料的吸附截留特征,探讨水生植物对水体环境中的微塑料是否具有吸附或截留效应,阐明水葫芦对微塑料的吸附与水体赋存微塑料的相关性,解析微塑料在湿地环境中的迁移特性,为鄱阳湖湿地环境中微塑料的管控及污染治理提供一定的理论基础与依据.在鄱阳湖流域赣江、抚河、信江、饶河和修水的五河水系入湖区和湖口出湖区共设置18个采样点,分别采集水表漂浮的水葫芦整株样品和水深约1 m处的水样,采用HNO₃（65%）-H₂ O₂（30%）混合试剂消解水样后抽滤分离水体及水葫芦体表微塑料;采用显微鉴定方法观察微塑料的颜色、粒径和形态等特征,采用Nano Measurer 1.2软件统计各流域水体和水葫芦体表中分离出的微塑料丰度;采用傅立叶变换红外（FTIR）光谱仪鉴定不同形态微塑料的聚合物成分.鄱阳湖流域各水体微塑料丰度处于中度偏高水平,丰度范围为65.5~353 n ·L^-1,且以0~0.5 mm范围内的小粒径微塑料为主,占各流域水体中微塑料的80%以上;各流域水葫芦截留或吸附的微塑料丰度范围为36~204 n ·kg^-1,且以0~1.5 mm范围内的小粒径微塑料为主,所占比例达80%以上;水葫芦吸附0~0.5 mm粒径范围内的微塑料丰度含量与水体中0~0.5 mm粒径范围内的微塑料丰度间呈显著相关,水葫芦对水体中占比较高的小粒径微塑料具有明显的吸附效应.鄱阳湖五河流域水体微塑料的聚合物成分以聚乙烯和聚苯乙烯为主体;各流域水体微塑料的丰度处于较高水平,以0~0.5 mm的小粒径微塑料为主,对水体生物及水环境易构成生态风险.各流域水葫芦对水体微塑料具有显著的吸附效应,且以吸附0~1.5 mm的小粒径微塑料为主;水葫芦吸附0~0.5 mm粒径范围内的微塑料丰度值与水体中0~0.5 mm粒径范围内的微塑料丰度间存在显著相关性;水葫芦对水体中的小粒径微塑料具有较强的吸附效应,可为水生植物吸附或截留水体环境中的微塑料提供一定的参考依据.     

Kinematic planning of slew manoeuvres after actuator failure for low-cost satellites

A kinematic scheme is presented which allows for planning attitude manoeuvres of satellites after actuator failure. The scheme relies on the identification of admissible rotation axes around which the control system can deliver torque components in spite of the failure. Two techniques discussed in the literature, based on a single rotation that either minimizes the angular displacement from a given target attitude or aims a sensor exactly along a prescribed direction, are compared with a new technique based on a two-step approach, which allows for achieving any prescribed attitude by means of a sequence of two feasible rotations. Dynamic simulation is used for analysing potential capabilities and limits of the considered kinematic approaches to manoeuvre planning of under-actuated satellites.     

烟气循环流化床（CFB-FGD）干法脱硫优化调整

本文分析了烟气循环流化床工艺的运行调节原理,针对电厂自身的特点,对吸收塔进出口烟温差及床层压降参数进行调整,提高了烟气循环流化床系统运行的经济性.最后根据此实践提出了系统运行中优化调整的可行性.     

六自由度动态模拟环境试验系统

六自由度动态模拟环境试验是考核车辆、舰船等运输工具在复线路面谱或海浪谱的运动条件和不同气候环境条件同时作用下的性能可靠性和行驶安全性及其使用寿命的重要模拟试验方法。本文详细介绍了为满足这一试验而研发的六自由度动态模拟环境试验系统。