Fisher判别法在煤与瓦斯突出危险程度预测中的应用

为了提高煤与瓦斯突出的预测精度,根据煤与瓦斯突出的综合作用假说,选取开采深度、瓦斯压力、瓦斯放散初速度、煤的普氏系数以及煤体破坏类型作为判别指标。利用国内典型突出矿井20个实测数据作为训练样本,建立煤与瓦斯突出危险程度预测的Fisher判别分析模型,并应用于其他待判样本的预测。结果表明:Fisher判别分析模型能够反映多因素对煤与瓦斯突出的影响,分类性能良好,误判率低,借助SPSS软件实现,具有计算简单的特点,是煤与瓦斯突出预测的一种有效方法。     

酚取代微生物的QSAR研究

计算了带７种不同取代基的２９种酚取代衍生物的分子表面积。用分子表面积,ＯＨ基表面积,代基当量作为描述变量,对上述化合物的ＭｉｃｒｏｔｏｘＲ毒性进行了回归分析,得到有一定意义的回归方程,其相关系数为０．９０。如果氰取代酚作为局外化合物,则相关系数达０．９４。说明这些参数在预言毒性方面有重要意义。     

三相生物流化床膨胀特性方程的研究

研究建立了描写三相生物流化床床层膨胀特性的经验关联式．当已知床内表观液速、表观气速和载体上生物膜厚度时,能比较准确地预测床层膨胀高度,为设计提供依据．与以往不同的是,本研究通过等效函数的设置和求解,用一个方程将两相床和三相床的膨胀特性描述出来．该方程能反映三相床低气速下的床层收缩行为,在气速为零时可还原为两相床．试验用反应器直径１．４ｍ,高６．５ｍ,载体为０．３—０．５ｍｍ的石英砂,射流曝气体内充氧．４种生物膜厚：５２,８０,１１５,１３７μｍ．试验用生活污水ＢＯＤ５４７．６—７７．２ｍｇ／Ｌ．     

根据现代企业理论探讨煤炭企业安全管理问题

煤炭行业属于高危险性行业,降低其事故发生率,提高安全生产水平是煤炭工作者孜孜以求的目标。笔者应用委托——代理理论对煤炭安全管理问题进行探讨,分析了安全投入与安全水平、安全投入与安全报酬、事故赔偿与安全水平等之间的关系,提出了煤炭企业改善安全现状的管理对策及建议,并认为事故赔偿金过低,不足以对企业形成足够的压力,不利于企业主动提高安全水平,应加大惩罚力度,提高惩罚成本和惩处率。     

安徽省地表137Cs的活度水平与分布特征

在安徽全省均匀布置采样点,采集222个样品并测定~(137)Cs.其活度,南部山区明显高于北部平原,全省平均值为834Bq/m~2.~(137)Cs高值带大体上为西北-东南走向,并在山脉两侧形成更高值区。     

航空电连接器腐蚀退化仿真研究

目的 探索当航空电连接器腐蚀退化时,其接触阻抗的变化规律,研究航空电连接器腐蚀退化对信号传输的影响规律。方法 首先对航空电连接器腐蚀退化的机理进行研究,建立其等效电路模型,然后分别对低频电连接器和射频电连接器进行仿真研究,提取阻抗参数,分析腐蚀退化对信号传输的影响规律。结果 接触电阻随着腐蚀程度的加深明显增大,接触电感随着腐蚀程度的加深变化不大,接触电容随着接触面腐蚀面积的增大而增大,随接触面间腐蚀厚度的增加而减小。接触电阻随频率的增加而增大,接触电感和接触电容随频率的增大基本保持不变。接触阻抗在低频时呈现感性特征,高频时呈现容性特征,阻抗幅值随频率的增加先增大、后减小,峰值出现在感性和容性转换频率处,腐蚀退化将使该转换频率减小。结论 对于低频信号,腐蚀退化将导致信号的衰减和延迟;对于高频信号,在转换频率处,信号的回波损耗、插入损耗和电压驻波比出现极值。     

Dioxins in the Venice lagoon

Venice is famous around the world for its uniqueness and architectural splendours, arts and the history of the “Serenissima Repubblica”, as it was known in the past, but few are aware that Venice economy is strongly dependent on the industrial activities based mainly on the adjacent Porto Marghera area. For many years, the lagoon that physically separates the city from the dry land has avoided association between the concern connected with the pollution derived from these industrial activities and the public perception of Venice. Since 1995, dioxins have appeared as a lagoon contaminant, and their presence, at such a level requiring immediate “in depth” studies and interventions, has been fully realized for decades.     

声屏障环境影响及其评价探讨

近年来,随着人们环保意识的提高,修建声屏障已成为解决交通噪声问题的首要选择,但与此同时也给沿线的居民和建筑物带来了其他的环境污染问题。在探讨声屏障应该考虑的环境影响因素的基础上,提出把声屏障环境影响评价纳入环境影响评价(EIA)体系中来的建议,为解决声屏障建设发展过程中出现的问题提供参考。     

Economic Growth and Marine Biodiversity: Influence of Human Social Structure on Decline of Marine Trophic Levels

Abstract:  We assessed the effects of economic growth, urbanization, and human population size on marine biodiversity. We used the mean trophic level (MTL) of marine catch as an indicator of marine biodiversity and conducted cross-national time-series analyses (1960–2003) of 102 nations to investigate human social influences on fish catch and trends in MTL. We constructed path models to examine direct and indirect effects relating to marine catch and MTL. Nations' MTLs declined with increased economic growth, increased urbanization, and increased population size, in part because of associated increased catch. These findings contradict the environmental Kuznets curve hypothesis, which claims that economic modernization will reduce human impact on the environment. To make informed decisions on issues of marine resource management, policy makers, nonprofit entities, and professional societies must recognize the need to include social analyses in overall conservation-research strategies. The challenge is to utilize the socioeconomic and ecological research in the service of a comprehensive marine-conservation movement.     

The effect of hunger on the strength and duration of the antipredator behavioral response of green frog (<Emphasis Type="Italic">Rana clamitans</Emphasis>) tadpoles

The activity level of prey reflects a trade-off between predation risk and foraging gain. A number of theoretical and empirical studies have shown that a prey's energetic state or the level of its resource should influence this trade-off (i.e., what the optimal activity level at a level of predation risk is). Here, I show that the energetic state of prey may also influence the duration of their antipredator behavioral response. Green frog tadpoles (Rana clamitans) reduced their activity level for a shorter time during exposure to the chemical cue of predatory larval dragonflies (Anax spp.) as their time since last feeding increased (i.e., as their energetic state decreased). Interestingly, the tadpoles strongly reduced their activity level upon cue exposure in all treatments. Thus, the relative activity level of tadpoles at different energetic states varied over time.