双牛头电火花机床平滑枕的轻量化设计

根据企业实际需求,对某型号双牛头电火花机床平滑枕结构的静、动态特性以及轻量化进行研究,在外形结构尺寸和所用材料的约束下,通过对不合理筋板结构的改进和针对主要尺寸参数灵敏度分析的基础上,最终得出优化设计模型。仿真分析结果表明:优化后的模型在确保静、动态特性的基础上,轻量化效果明显,质量减轻达12.07%。     

Assessing ecological risks of offshore wind power on Kattegat cod

Offshore wind power is expanding with particular development plans in the Baltic and the North Sea. To reassure an environmentally acceptable development, regulatory authorities need to make informed decisions even when evidence and experience are scarce. In this study Ecological Risk Assessment (ERA) has been applied on a wind farm project in Kattegat, proposed within a spawning ground for the Kattegat cod, a threatened population of Atlantic cod (Gadus morhua L.). Six stressors with potential impacts on cod and related to wind farms were investigated. Three of them – extreme noise from pile driving, noise from vessels, and disturbances due to cable-trenching – are related to the construction phase, while lubricant spills and noise from turbines together with electric fields from cables are related to the operation phase. The ecological risk was derived from the combined likelihood and magnitude of potential adverse effects from stressors to the cod population using a weight-of-evidence (WOE) ranking procedure. Available evidence was evaluated based on its reliability, and contradictory arguments were balanced against each other using evidence maps. The option of performing hazardous construction events (e.g. pile-driving) outside biologically sensitive periods was incorporated in the assessment. It was shown that the construction of the wind farm poses a high risk to cod, as defined by the ranked and combined likelihoods and magnitudes of adverse effects. However by avoiding particular construction events during the cod recruitment period ecological risks can be significantly reduced. Specifically for this case, ecological risks are reduced from high to low by avoiding pile-driving from December through June, which confirms previous indications that pile-driving is the most ecologically hazardous activity of offshore wind power development. Additional risk reduction is achieved by avoiding cable trenching from January through May. The study thus illustrates the effectiveness of time-planning for risk reduction. Importantly, the study illustrates how combined ERA and WOE methods can be valuable for handling uncertainties of environmental impacts within offshore industrial development.     

考虑负荷容量的改进型二阶灵敏度分析SV系数在城乡配电网无功选址中应用

在考虑负荷容量的前提下,针对灵敏度优选补偿集合存在的四个问题,在二阶无功灵敏度分析的基础上进一步探讨二阶无功灵敏度对线路总网损的影响,并通过极限与微分的公式推导得出了当二阶无功灵敏度与线路负荷相乘可以作为二阶无功灵敏度选址的依据,将其定义为SV系数,选取SV系数较大的节点作为无功补偿节点,并通过改进粒子群算法加以定容验证,以PGE69节点进行验证实验,验证了该方法的可行性和可靠性。     

A new ultrasonic angle-beam technique for sensitive evaluation of closed cracks

This paper is on the ultrasonic nondestructive evaluation of smaller cracks in the size range of 1–7 mm. Sensitive evaluation of the crack that was originally present or that developed during operation is imperative for assessing the integrity of structural components. In order to develop a method for the enhancement of sensitivity of ultrasonic evaluation of closed cracks, the principle of a new angle-beam approach is proposed, where the use of an oblique longitudinal wave with a small angle of incidence upon the specimen surface is emphasized. The crack treated exists nearly vertically on the back surface of the specimen. In contrast with the normally incident wave beam, the effect of angular incidence on the ultrasonic response due to a crack is investigated in an attempt to predict the optimum angle of evaluation. The sensitive feature of the present angle-beam technique is discussed in light of comparison made with the usual methods of normal incidence and large-angle beam technique. Ultrasonic measurements performed on the closed fatigue-cracked specimens show that the method offers bright prospects for the sensitive evaluation of small, closed cracks.     

压电石英晶体生物传感器及其检测方法

压电石英晶体生物传感器是一种生物传感设备,能快速,简单、无需进行任何标记,并且有选择性地对一些生物分子进行实时检测。已在临床检验、疾病诊断、生物医学、环境监测、污染控制、军事、食品安全以及工业等方面得到了广泛的应用。     

城市废弃采石场改造利用与生态设计——以广州番禺区六大连湖主题公园为例

近年来随着我国经济实力的增强和生态环境保护意识的提高,人们开始重视城市废弃采石场的生态修复与改造利用。该文以广州番禺区六大连湖主题公园为例,探讨如何在生态恢复基础上。利用原矿坑独特景现进行项目策划与生态设计,把原来生态脆弱、环境恶化的废弃采石场改造成为一个生态、民俗文化为主题的综合性生态公园。该案例对国内废弃采石场的改造利用具有一定的借鉴意义。     

生态学视野下的豫北山地民居景观分析——以河南省林县石板岩民居为例

特殊的峡谷地形地貌、特色的石板房建筑与环境有机结合,构成了豫北山地聚落特有的魅力景观。该文从河南林县石板岩村落独特的地域景观入手,详细分析豫北山地聚落在规划选址、营造技术和绿化景观等方面蕴含着生态思想。并进而提出山地聚落景观的可持续发展途径应是生态、社会文化、经济和建筑环境等多方面的协调发展。     

基于生态逻辑的建构意识初探

在商品化社会大潮中,建筑的发展也受到影响。隈研吾认为,现代主义运动在二战之后的胜利,正是因为他们将建筑商品化地呈现在人们面前。在现代主义运动过去一百多年之后的今天,中国建筑的商品化思维愈演愈烈,甚至走向了一种极端。该文从当今我国建筑现状出发,阐述了在我国建立普遍的建构意识的必要性;同时结合当今建筑所处的大环境,讨论了建构意识如何与当今现实问题结合,提出一种环境友好的建构逻辑,即生态逻辑的建构意识,并对其本质及重要性予以讨论。     

结合环境伦理学的城市生态规划与设计

城市生态问题的实质,是人与环境关系的失范,是环境伦理学范畴。城市生态规划是在大尺度上处理城市发展与生态环境保护关系的实践科学,需结合环境伦理学的最新理论与方法进行原则思辨。在具体的规划设计方法上应尊重自然,正确设定城市发展的限度与阈值,在城市自然生态可承受范围内,采取与环境更加包容的发展策略。要按照自然优先、代际公平、互利合作的原则重建城市近自然。按照生态承载力要求为城市的发展设定上限,在满足城市发展的同时取得环境健康的统一,同时转变增长方式,取得人与自然的协同发展。这样就能够从工业文明走向生态文明,建设更加可持续、健康的城市。     

国内生态足迹研究范围的相关文献综述

生态足迹概念于20世纪90年代提出,1999年正式引入我国。从该概念的引入至今,国内的诸多学者对于生态足迹的研究已有数年的成果,成果中不仅包括了对生态足迹研究方法的应用,更有大量的实证研究。本文是在大量分析前人的实例研究基础上,将所有的实例研究成果根据研究范围的不同分为国家级、省级、市级、以若干省或市组成的区域级和特定小区域五个层次,对于每个层次的相关研究进展以及存在的问题进行了综述,并对未来研究范围的扩展做出了展望。