小断面机掘工作面除尘技术的研究

1 前言 随着煤矿机械化程度的提高,高效、大功率掘进机的使用,机械化掘进工作面的粉尘产生量急剧增加。掘进机工作时产生的大量粉尘弥漫整个工作面,粉尘浓度最高可达1～2g/m~3。高浓度的粉尘严重影响矿工的身体健康,威胁矿井安全。我国机掘断面在10m~2以下的较多,采用一些国内外的大型除尘系统,     

职业适应性测试评价及应用

前言 随着科技的进步,经济的发展,工业自动化程度越来越高,人机系统越来越复杂,一方面虽然减轻了作业者的体力劳动负荷,但也增加了作业者的心理负荷,另一方面对作业者提出了新的和更高的要求。不同的职业(工种或岗位)具有不同的作业性质和特点,例如,我国“八五”科技攻关项目就将涉及重大危险装置操作的100多个工种划分     

Design and validation of a practical index for trauma assessment

In the past 20 years a variety of indices have been suggested for measuring the severity of trauma, however none of them meets the requirement of being a simple and objective instrument that can be utilized efficiently by lay persons and providers of health services without previous experience in triaging. A new system has been proposed which meets this requirement and which has been validated with 197 injured persons at the emergency ward of the Valle University Hospital in Call, Colombia. The instrument showed a high level of concordance with the conventional triaging method and classifies victims into four categories: critical with recovery unlikely, critical but recoverable, moderately serious, and ambulatory. There is discussion on the reliability of this instrument and it is recommended that it be validated with victims from larger disasters. Regardless, it has the advantage of being specific and free of the subjectivity that characterizes other indices.     

The role of socio-economic data in food needs assessment and monitoring

This paper reviews six case studies examined as part of a project to review targetting methodologies employed by non-government organisations in Africa during the 1984-6 food crisis. Most agencies have not yet fully evaluated the role of data in informing policy decisions during their respective emergency programmes. The case studies presented reflect a wide variety of approaches to targetting emergency food aid that are based largely on the use of 'socio-economic' data. The recent emergency relief operations in Africa seem to indicate a change in relief agencies' approaches to the assessment and monitoring of needs of the affected populations. Earlier dependance on nutritional data has given way to an increasing reliance on the use of socio-economic indicators. There was a wide variation in the case studies of the type of indicators collected and utilised in needs assessment and monitoring. There were those who relied almost exclusively on nutritional data to target resources during the 1984-86 African crisis, and others whose experiences during that period lead them to attach more weight to socio-economic data. Other agencies appear to have recognised the problems of relying solely on nutritional data to target food aid during their 1984–86 emergency programmes, and thus more or less abandoned classical anthropometric surveys in their needs assessment and monitoring methodologies during this period. Thus nutritional data has a less significant role in the decision making process than previously had been the case.     

Factors affecting trace-metal bioaccumulation in Finnish headwater lakes

Fourteen unpolluted Finnish headwater lakes with pH values varying from 4.8 to 7.0 were studied for trace-metal concentrations in water, sediment, aquatic plants (Nuphar luteum L., Sparganium sp.), aquatic insect larvae (Limnophilus sp., Phryganea sp.) and fish (Esox lucius L., Perca fluviatilis L., Coregonus sp., Salvelinus fontinalis L., Salmo trutta L.). Trace-metal deposition was estimated by analysing the snowpack. Non-parametric correlation analysis was carried out between trace metal concentrations in biota and pH, ANC, TOC, CA + Mg concentration in water and a given metal concentration in water and sediment. Bioaccumulation of several trace metals increased with increasing acidity and decreasing ANC in water. This was especially true for Pb and Cd. Aquatic plants were, in general, the best indicator group concerning differences in trace-metal bioaccumulation in lakes with different acidity. There was some evidence that a higher concentration of TOC in water may reduce bioaccumulation of Pb, Cd and Zn in aquatic plants and fish. The copper concentration in sediment was the only background variable explaining Cu concentration in aquatic insects. Multivariate analysis of the whole background data gave comparable preliminary results. Over 80% of the trace metal concentrations in biota of different lakes was explained by the background variables. In general, elevated concentrations of most of these trace metals can be expected to occur in the biota of acidified low calcareous lakes.     

A review of the likely causal pathways relating the reduced density of breeding dippers Cinclus cinclus to the acidification of upland streams

Previous work has shown that the breeding density of a bird characteristic of upland streams, the dipper Cinclus cinclus, is markedly reduced at low pH in both Wales and Scotland. Populations also declined when streams became more acidic. Evidence of causal explanation for these relationships is that: (1) Food quantity is reduced in acidic streams, and important prey, including those rich in calcium, are scarce; (2) Blood chemistry in pre-breeding birds differs between acid and circumneutral streams, with plasma calcium reduced in those breeding at low pH. Skeletal sources of calcium are probably limited; (3) The time spent foraging by pre-breeding birds on acidic streams is markedly increased, even though overall energy costs on acidic and circumneutral streams are similar. Body condition is inferior to birds on circumneutral streams; (4) Egg laying is significantly delayed on acidic streams irrespective of an effect on laying of altitude, and clutch and brood sizes are significantly reduced; (5) Eggs are lighter and shells thinner at low pH; (6) Chick growth is reduced at low pH; (7) Contamination by heavy metals and persistent organochlorines is low in the populations on acidic streams and cannot explain the impaired breeding performance. None of these features can exclude the possibilities that acidic streams either hold populations of poor quality birds, which show the above features, or that acidity affects the breeding ecology of all dippers that attempt to breed at low pH. The qualitative outcome of these two alternatives is identical.     

潜力的兑现还是赢者的诅咒——来自跨区域能源项目电价反向招标的证据(2006—2020年)北大核心CSCDCSSCI

能源项目反向招标作为替代统一上网电价的市场自由化政策在全球范围内有效提高了各类能源的降本效率,但近年来项目投标运营主体却陷入了盈利瓶颈。针对这一现象,该研究修正关联价值模型,构建动态竞标决策框架,评估项目成本和产出不确定时能源投资企业附加动态预期的最优投标电价决策,并利用2006—2020年欧美和亚太地区3000余个大型电站电价招标及项目后期运营的样本数据进行检验。结果显示:①几乎全球能源投资企业都会陷入“过分乐观”预期导致的“赢者诅咒”怪圈,最终所持项目的实际运营收益远低于预期。投标主体往往更容易低估项目建设和运营的成本压力和风险,并高估项目的电力产出和收入稳定性,尤其在联合投标机制被取消和禁止以后,招标结果甚至变得更加激进。由于经历过超预期技术进步的持续修正,过度乐观的预期超越了行业内生性的技术进步,成为持续施压电价下降的重要动力。②当前的能源产业特别是风、光新能源未能有效发挥行业潜力,随着新能源行业技术革新,它较之火电项目表现出更加激进的竞标策略。在内卷化竞标压力下,内生性的成本优化阻碍了新能源项目的潜力发挥,当期成本是导致其陷入“赢者诅咒”的最重要原因。③在考虑学习曲线效应等诸多因素以后,除了企业的融资成本优势以外,样本数据并未发现包括经验、市场环境等内外部因素能使企业跳出这一怪圈。甚至在过去的5年左右时间里,“赢者诅咒”导致的项目投资利润下降超过市场技术进步因素,一度成为风电和太阳能项目电力价格下降的最主要因素。因此,健康可持续的能源产业政策需要立足于上游持续的技术革新,完善绿色金融为基础的资本市场体系,确保提供优质项目服务能源消费者,并为能源项目投资者提供来自资本市场的认可和支持。     

江苏省环境监测系统进行监测分析质量大检查

由江苏省环保局、省监测站具体领导、并由省和各市监测站质量管理人员组成的“江苏省环境监测质量管理组”,于今年9月1日至13日分南北两片对全省十一个省辖市监测站实验室的监测分析质量进行了全面检查。     

湖北省召开大气环境监测网站工作会议

会议对全省网络建设基本情况、网站设置内容落实情况、监测质量保证及网站建设中存在的问题等作了全面总结,讨论和修订了《湖北省大气环境例行监测技术规定》.省中心站还表扬了多年来不间断监测、上报数据齐全、报表清晰和规矩的网站,同时对今后网站工作提出了要求.     

用新制蒸馏水代替重蒸蒸馏水配制测定亚硝酸盐氮、氨氮、酚的试液

用新制蒸馏水代替重蒸蒸馏水配制测定亚硝酸盐氮、氨氮、酚的试液ＣｏｍｐｏｕｎｄｅｄＴｈｅＳｏｌｕｔｉｏｎＮｉｔｒｉｔｅ－Ｎ，Ａｍｍｏｎｉａ－ＮａｎｄＰｈｅｎｏｌＷｉｔｈＮｅｗ－ｍａｄｅＤｉｓｔｉｌｅｄＷａｔｅｒｉｎｓｔｅａｄｏｆＡｆｒｅｓｈＤｉｓｔｉｌ...