泉州市行政管理中心基坑控制爆破及安全技术

介绍了基坑控制爆破和安全技术,包括爆破设计、爆破参数的选取、装药结构、起爆网路的设计和安全防护措施,可供类似工程参考.     

深基坑降水设计及降水对周边环境影响的分析

为了更好地解决深基坑降水问题,本文分析了基坑降水的主要作用,介绍了常见的基坑降水方法与适用范围,并以武汉市瑞安街永清片区某深基坑降水工程为例,在结合其工程地质及水文地质条件和明确降水设计要点的基础上,选取合理的降水方案进行了深基坑降水的优化设计,同时探讨了深基坑降水对周边环境的影响以及相应的治理措施。     

基于数字处理技术的航空铝合金材料孔蚀率计算研究

通过航空LD2材料的加速腐蚀试验,获取该材料试件不同腐蚀周期的腐蚀形貌图像,对腐蚀形貌图像进行基于数字处理技术的一系列处理,最终通过二值特征提取方法得到二值化腐蚀图像,并依据二值化结果计算LD2材料不同腐蚀周期的孔蚀率。计算结果表明,此种方法得到的孔蚀率变化规律与该材料的电化学腐蚀机理较为吻合,并且该方法克服了传统方法计算孔蚀率精确性差的问题,为航空铝合金的孔蚀率计算及相关分析提供了新思路。     

Influence of fur trade,famine, and forest fires on moose and woodland caribou populations in northwestern Ontario from 1786 to 1911

Hudson’s Bay Company records were used to estimate the 1786–1911 annual number of moose (Alces alces andersonii) and caribou (Rangifer tarandus caribou) involved in trade by northern Ojibwa natives to the company post at Osnaburgh House (51°10′N 90°15′W) in northwest Ontario, Canada. The human population for the early 19th century, and the number and severity of human starvations from 1786 to 1911 were estimated. The extent of forest fires in the region around Osnaburgh was documented using a “fire-day” index computed from Hudson’s Bay Company journals and using qualitative archival information. It is argued that the human population was too small to have caused the observed early 19th century moose and caribou population decline solely through predation. Likewise, severe early 19th century famines were caused by climatic factors rather than by declines in moose and caribou numbers. Habitat change caused by increased forest fires correlates with the observed decline of caribou, while moose increased and subsequently collapsed as winter shelter was destroyed. A burgeoning human population, sustained during winter food shortages on potatoes donated by the Hudson’s Bay Company, then kept ungulate populations to low levels until the late 19th century. Only then did maturing forests and a new outbreak of fires provide renewed habitat for resurgences of, respectively, caribou and moose.     

黄土高原极强烈侵蚀（灾害性）的降雨产流产沙特征

本文通过对４５场极强烈侵蚀降雨、产流、产沙特征的统计分析,得到了极强烈侵蚀降雨、产流、产沙特征与过程变化的数量指标,并对岔巴沟和韭园沟的１０次极强烈侵蚀作了典型分析。     

基于差异进化支持向量机的坑外土体沉降预测

就用支持向量机(SVM)预测基坑外土体沉降而言,通过差异进化(DE)算法构造适合的决策函数十分重要。在确定坑外土体沉降函数的基本形式下,进行参数反演。后将得到的解析式作为SVM的决策函数,再进行核函数转换,从而使SVM的曲线拟合更加快速,预测更加准确。对大连地铁湾家车站基坑坑外土体的沉降数据的分析及预测的结果表明,使用SVM-DE算法在计算数据量、计算消耗时间和预测精度方面优于2种方法单独使用。     

SAMPLING ACCURACY OF PIT VS. STANDARD RAIN GAGES ON THE FERNOW EXPERIMENTAL FOREST1

ABSTRACT: Catch in standard (unshielded) rain gages exposed 3 feet above the land surface was compared with catch in pit (buried) gages exposed 1 inch above the land surface. These tests confirmed that catch in standard gages under estimates point rainfall in forest openings, as well as in conventional weather stations. Pit gages caught significantly (P=0.05) more rain than did standard gages at each of four locations tested. Catch increases ranged from 2.3 to 3.4 percent.     

露天煤矿开采对生态环境的影响及其亟待解决的问题

主要就露天矿山开采对区域生态环境的影响因素等问题进行了研究和探讨,并对目前国内露天煤矿复垦现状、及今后应着力解决的主要问题进行了概要分析。     

Portfolio-Based Electricity Generation Planning: Policy Implications For Renewables And Energy Security

Renewable generating technologies offer an effective means for climate change mitigation. Policy makers, however, are wary because of the widespread perception that these technologies cost more than conventional alternatives so that increasing their deployment will raise overall electricity generating costs. Energy planning represents an investment-decision problem. Investors commonly evaluate such problems using portfolio theory to manage risk and maximize portfolio performance under a variety of unpredictable economic outcomes. Energy planners need to similarly abandon their reliance on traditional, “least-cost” stand-alone kWh generating cost measures and instead evaluate conventional and renewable energy sources on the basis of their portfolio cost – their cost contribution relative to their risk contribution to a mix of generating assets. Energy security generally focuses on the threat of abrupt supply disruptions. This paper suggests a more profound aspect: mitigating fossil price volatility. An extensive body of research indicates that fossil volatility significantly disrupts the economies of consuming nations, potentially exacting hundreds of billions of dollars from the US and EU economies alone. Energy security is reduced when countries hold inefficient portfolios that are needlessly exposed to fossil price risks. This paper describes essential portfolio-theory ideas and uses three case studies to illustrate how electricity-generating mixes can benefit from additional shares of wind, geothermal and other renewables. Compared to existing, fossil-dominated mixes, efficient portfolios reduce generating cost while including greater renewables shares in the mix thereby enhancing energy security. Though counter-intuitive, the idea that adding more costly renewables can actually reduce portfolio-generating cost is consistent with basic finance theory. An important implication is that in dynamic and uncertain environments, the relative value of generating technologies must be determined not by evaluating alternative resources, but by evaluating alternative resource portfolios.     

深基坑拉锚联合支护结构设计及工程应用

深基坑拉锚式支护结构由于其经济可靠而且施工快速简便．已经在许多深基坑工程得到了迅速推广应用。结合工程实例，通过分析工程场地周边环境与工程地质条件．经方案比较后，采用拉锚式支护方案，着重阐述了拉锚式支护方案设计与施工工艺。工程实践表明，该设计方案是可行且经济的，对场地狭小、周边环境复杂的大面积深基坑工程，拉锚式支护体系具有独特的优势。