硫化矿石自燃倾向性的实验室测定方法与应用

硫化矿石自燃的防治一直是含硫矿床面对的主要安全问题。准确地测定硫化矿石自燃倾向性．对保护工人生命安全、保证矿山正常生产、充分利用矿产资源等具有十分重大的意义。通过对现有硫化矿石自燃倾向性测定方法进行全面而系统的分析．介绍了一种可靠的硫化矿石自燃倾向性的实验室测定方法．并对每一个步骤做了具体的阐述。最后,将该方法应用于矿山实际．得到了准确的测定结果。     

近距双线盾构隧道开挖诱发地层变形演变规律及数值模拟

双线平行隧道盾构施工相互扰动作用对其诱发的地层变形分布特征和演变规律影响显著。以某地铁双线盾构隧道工程为例,考虑双线平行隧道间距与盾构施工相互作用影响,采用数值模拟和现场实测相结合的方法对双线平行隧道盾构施工引起的地层变形演变规律进行了对比分析,并提出了考虑近远距状态的双线平行隧道盾构施工地层变形预测模型。研究结果表明,双线盾构隧道施工地层竖向变形曲线由“V”形发展为非对称“W”形分布,沉降槽宽度由6D扩大为10D,地层深度越深非对称“双峰”特征越明显;地层水平变形曲线以两隧道中线为轴线呈反对称分布,两隧道间区域土体变形受施工扰动影响显著;地表沉降曲线分布随双线隧道近远距变化由深“V”形—浅“V”形—“U”形—浅“W”形—深“W”形—两独立“V”形演变,采用L cr=2CKH可作为双线平行盾构隧道近远距状态临界判据,本文提出的预测模型能较好地反映近远距状态及施工相互扰动对双线平行隧道盾构施工地层变形的影响规律。研究成果可为类似地铁隧道盾构施工变形预测与精细化控制提供科学参考。     

Detecting pattern in biological stressor response relationships using model based cluster analysis

Environmental monitoring of aquatic systems is needed to estimate the quality of the systems, to evaluate standards and to study stressor–response relationships. Monitoring programs often focus on the collection of biological, chemical and physical measures of the system. An important concern is the effect of chemical and physical stressors on the biological community. Evaluation of relationships may be difficult as the extent of the relationship is not known. From a management perspective, interest is on what factors affect the biological community and where these factors have an influence. The focus of this paper is on the use of regression based cluster analysis as a tool for finding relationships between a single biological response and a suite of environmental stressors. The approach to cluster analysis uses a penalized regression classification likelihood and Markov Chain Model Composition Monte Carlo. This approach allows for simultaneous development of regression models and clustering of the regression models. The method is applied to the analysis of a data set describing stressors/response relationship in Ohio.     

A finite element method to solve a population dynamics stage-structured model of intertidal barnacles

Many marine organisms are fixed or highly sedentary as adults but the adult population may be strongly dependent on the oceanic transport of planktonic larvae. In order to assess interactions between oceanographic and biological processes that determine the population dynamics of marine organisms with a sessile adult phase restricted to the coastline and a planktonic larval phase, we present a stage-structured finite element model for the barnacle Balanus glandula that inhabits the rocky intertidal zone of central California, USA.     

National Responsibilities in European Species Conservation: a Methodological Review

Abstract: One particular challenge in reducing the loss of biodiversity by 2010, as agreed on at the Earth Summit in 2002, is to assign conservation tasks to geographic or administrative entities (e.g., countries or regions) on different geographical scales. To identify conservation tasks, it is imperative to determine the importance of a specific area for the global survival of a species. So far, these national or subnational responsibilities for the conservation of species have been included differently in methods prioritizing conservation. We reviewed how 12 European and 3 non‐European methods determined national conservation responsibilities and evaluated the international importance of a biological population. Different countries used different methodologies, which made a direct comparison of assessments of national responsibilities among countries extremely difficult. Differences existed in the importance criteria used. Criteria included population decline, range reduction, rarity status, degree of isolation of a population, endemism, proportional distribution, and geographic location. To increase comparability, it is imperative to develop criteria for which data are generally available and to standardize the methodology among countries. A standardized method would allow conservation decisions to be based on the conservation status of a species and on the responsibility of a geographic or administrative entity for the survival of a species. We suggest that such a method should use a scalable index of proportional distribution, taxonomic status, and the distribution pattern of a taxon or species as key elements. Such a method would allow for the creation of hierarchical lists and would be highly relevant for parts of the world with multiple political jurisdictions or state unions and for nations with regional governmental structures. Conservation priorities could then be reasonably set by combining national responsibility assessments with the international conservation status of a species.     

日本废弃物的管理制度与研究现状 Ⅲ.日本废弃物的试验分析方法体系 (B)产业废弃物的采样与制样方法

本文介绍了日本产业废弃物的采样方法并详细介绍了溶出试验和含量试验试液的制备方法及其适用范围,对测定重金属用试液的前处理方法也做了简要介绍。     

重铬酸盐法测定化学需氧量(CODcr)的不确定度评定

介绍滴定法测定水中CODcr的不确定度分析。用因果图分析了测量器具、标准溶液、环境条件和测量重复性等因素对测量不确定度的贡献,分析结果给出水中CODcr测量的扩展不确定度为2.2%。     

改进GC/ECD法连续测定大气中的CFCs

基于气相色谱仪 (GC)和电子捕获检测器 (ECD) ,设计了一种连续测量大气中痕量氯氟烃的自动系统。系统色谱基线稳定 ,分离效果好 ,定性、定量准确可靠 ,系统高度自动化 ,长期运行无需人值守 ,自动校正数据 ,定时进行严格的质量控制 ;系统具有较高的现场测量频率 (6次 /h) ,改进的反吹 /外切设计使CFCs色谱峰不再受氧峰的干扰 ,大大延长了检测器的寿命 ,使长期连续观测成为可能。系统设计在分离效果方面优于世界气象组织 (WMO)全球大气监测网 (GAW )目前所使用的测量大气本底CFCs的方法 ,采用美国EPA认可的标气 ,外标工作曲线法测定大气CFCs的浓度 ,最低检测限可达1pL/L ,检测精密度小于 1 % ,准确度在± 3%之内 ,可用于我国本底大气观测站对CFCs的连续测定     

川南页岩气区块生命周期用水核算

选取川南页岩气区块为研究对象,运用过程生命周期评估和投入产出生命周期方法核算页岩气开采生命周期的直接和间接用水量,并与美国Marcellus页岩气区块用水量进行比较。川南区块总直接用水量为22 928 m^3/井,高于Marcellus区块的总直接用水量15 320 m^3/井。从生命周期阶段来看,川南页岩气开采钻井和压裂阶段的直接用水均远大于Marcellus区块。结合水环境管理指标,自然资源禀赋条件主要决定了直接用水量的差异。川南区块总间接用水量为25 098 m^3/井,超过总直接用水量,约为Marcellus区块总间接用水量的3倍。除井场准备阶段外,其余阶段的间接用水量均大于Marcellus区块,间接用水量的差异与钻井和压裂过程的添加剂、能源使用量和全行业用水效率有关。减少川南区块页岩气开发用水量的主要途径包括提高钻井液和压裂液回用率、改善钻井和压裂添加剂使用效率、提高柴油和电力等能源利用效率和全行业用水效率。     

Investigation of three system shut-down strategies alongside optimization suggestion for proton exchange membrane fuel cells via in-situ measurements

ABSTRACT

Carbon corrosion caused by H₂/O₂ interface during the shut-down process is one of the factors that exacerbate the overall degradation of proton exchange membrane fuel cells (PEMFC) in automotive applications. Numerous studies have shown that system strategies are beneficial for reducing the duration of H₂/O₂ interface and alleviating performance degradation. In this paper, three different shut-down strategies are investigated and compared based on the internal behaviors acquired by in-situ measurements. For the three shut-down strategies, reverse current and high potential are mainly observed in a lower constant current and constant power strategy. Comparatively speaking, the internal uniformity of the cell under constant current and power load is better than that with constant voltage strategy when the shut-down time is about the same. The results suggest that adopting a higher constant power load followed by a larger voltage load during the shut-down process can effectively shorten the shut-down time and relieve carbon corrosion. These results add significant new insights into the shut-down process and will be of practical importance in directing design of combined shut-down strategy that can withstand carbon corrosion.