Geosynthetics in erosion control — the principles

The principles of erosion control are basic, but geosynthetic materials manufactured and marketed for erosion control applications have varied significantly in the last decade. The problem of soil retention, protection, revegetation, and turf reinforcement can be solved with many different materials, both organic and synthetic. Specific material properties must, however, be met to achieve proper performance.

This paper provides a review of the primary geosynthetic materials used for erosion control and their basic applications, including blankets for ground cover, geotextiles for filter protection beneath armor, geotextiles for silt control, synthetic mats and blankets used for erosion control/revegetation and turf reinforcement. The paper also includes several generic, physical-property criteria for the materials to be used in the primary applications discussed.     

Durability of soil-cement for building purposes — rain erosion resistance test

In this paper, the effects of compaction pressure (moulding pressure), simulated rainfall, and cement content on the durability of soil-cement bricks have been investigated. The results show that the resistance of the bricks to erosion by raindrops was enhanced by increase in compaction pressure and cement content. The bricks stabilised with 5 percent cement and compressed at 8 MN/m², compaction pressure were found durable to rain erosion. Higher cement content and/or higher compaction pressures yielded very negligibly higher weight losses. These later cases are considered uneconomical. The spray pressure (250 Kn/M²), distance from the face of brick (140mm), duration of spray (3 hours), were also found adequate for rainfall durability tests on cement stabilised soils.     

切坯机使挤出更完美——切坯技术现状

<正>切坯机是挤出机的主要部分,因为它是黏土泥条连续地通过切坯机制作最终产品的唯一方法。同时,切坯机也是切割后坯体全自动托盘处理、码坯、输送设备的一部分。从第一台人工切坯机到现在电子控制自动化切割设备,切坯机已经经历了快速和全面的发展。     

弦支结构体系研究进展

在阐述预应力钢结构发展历程的基础上,根据预应力钢结构中构件类型组成,将预应力钢结构分为刚性、刚柔混合和柔性三种预应力钢结构类型,其中刚柔混合预应力钢结构中的弦支结构是一种典型的预应力钢结构,是目前应用最广泛的结构体系之一。对于预应力钢结构的核心构件——拉索的温度线膨胀系数,建议今后工程设计时采用以理论分析和试验研究为基础的数据,即钢丝绳、钢绞线、半平行钢丝束三种索材的线膨胀系数值分别为1.92×10-5,1.38×10-5,1.87×10-5/℃。在分析弦支结构体系概念的基础上,将其分为平面弦支结构、可分解的空间弦支结构和不可分解的空间弦支结构三类,并对弦支结构体系中拉索的数值模拟理论进行了总结分析。随后分别针对三种弦支结构类型,对其发展历程、结构构成、结构特点以及工程应用进行了分析总结。     

Landscape photography: from art to now — artists' contemporary concerns

An account of the use of landscape as subject-matter as a basis for the exploration of personal concerns and the search for self by various 20th Century photographers. Particular reference is made to the landscape photography of Eugene Atget, Edward Weston and Bill Brandt.     

Detection of smoke gases by solid state sensors — A focus on research activities

Conventional smoke detection in fire alarm systems is based on a measurement of either physical properties of smoke aerosols (ionization and optical detectors), temperature increase (thermal detectors) or electromagnetic radiation emitted by the fire (radiation detectors). Not much emphasis has been put on smoke gases as signatures of various types of fires. In this paper the most elementary gases produced in CEN-norm fires are qualitatively discussed in order to define levels of gas concentrations reached on time scales typical of early fire warning. Based on that information, various principles and the current state of the research and development of solid state gas sensors are presented and discussed. These are, in particular, the solid state electrolyte, the metal oxide semiconductor, the silicon semiconductor device element and, finally, the microcalorimeter. It is concluded that, with the exception of the last mentioned operating principle, solid state gas detection could provide a viable alternative or additional means for the detection of smouldering or pyrolytic fires at an early stage.     

Planning history in Australia: The state of the art

Over the last two decades, planning history in Australia has firmed as both a specific research field and pragmatic endeavour geared to planning practice. The emergence of an identifiable planning history strand across the borders of such disciplines as planning, political science, human geography, and history in the mid‐1970s gained much of its rationale from other developments at this time, including the academic legitimation of urban studies and urban history, an unprecedented level of governmental interest in urban and regional development, reassessment and reaction to traditional land use planning, and the benevolent imprimatur of the British Planning History Group. From the vantage point of the early 1990s, a substantive literature can now be critically surveyed. Diverse if not fragmented, parochial and sometimes quirky, the general nature of this body of work partly reflects the spatial isolationism and parochialism that have been hallmarks of Australian cultural and political development. Beyond the straitlaced general surveys of state, city and metropolitan planning, several established lines of inquiry are evident, notably colonial town layout, civic design, the impact of planning movements, evaluations of metropolitan planning, political conflict, and federal urban policy. The links with cognate fields such as housing, landscape architecture and, increasingly, environmental studies, are close. Alongside these general themes have come more distinctively Antipodean preoccupations like the planning of Adelaide and Canberra as well as the work of Walter Burley Griffin. Future challenges lie in more original research, integration, theory development, and policy relevance.     

基于分权状态下的授权艺术

授权与分权是现代组织中权力分散的两条基本途径,两者既相互区别又相互联系。分权是一条组织工作原则,授权是一门领导艺术。在新的历史时期,面对复杂多变、竞争激励的外部环境,组织内部决策的复杂性和时效性已空前提高,此时,作为管理组织的领导者,已不可能事必躬亲、事无巨细,必须正确地认识授权的重要性、掌握授权的艺术。敢于授权又善于授权已成为现代领导活动的重要特征及目标追求。在现代组织中,权力的分散一般可以通过两条基本途径来实现:一是组织层级化设计中的分权(即制度分权);二是作为管理组织的领导者在工作过程中的授权。尽管授…     

视频火灾探测系统现状分析

介绍了国内外目前在视频火灾探测领域的几种典型产品以及视频探测算法的研究现状,分析了各个系统及算法的特点,并对此领域的发展前景进行了讨论和展望。     

浅谈升降脚手架技术发展现状和安全管理

介绍了升降脚手架技术的发展现状,针对升降脚手架施工中易出现的薄弱环节,提出了升降脚手架安全生产管理的重点。     

锈蚀钢筋与混凝土粘结性能研究进展

粘结性能退化是锈蚀钢筋混凝土构件力学性能下降的主要原因之一.锈蚀对钢筋与混凝土粘结性能的影响已成为混凝土结构耐久性研究的重要内容.文章全面地介绍了钢筋锈蚀及粘结性能测试的试验方法;系统地回顾与评述了锈蚀引起的粘结强度演化规律、粘结滑移本构关系以及粘结退化对结构承载力的影响等方面的研究进展.     

Techno-aesthetics in architectural discourses:A state of the art review

Since the beginning of the First Industrial Revolution,technology and its impact on art and design have been a topic of discussion.With the rise of digital technologies,there has been a renewed interest in exploring the relationship between technology and aesthetics.The aim of this paper is to clarify the concept of techno-aesthetics and make it a more accessible field of study by identifying its key discourses.In order to understand how technological ob-jects have been evaluated in architectural history,a systematic review of 177 studies was con-ducted.The collected literature was analyzed using Kant's characteristics of aesthetic judgment,discourse analysis techniques from Foucault's methodology and Laclau and Mouffe's discourse theory.This helped in creating a framework for classifying the literature.The study analyzed results based on five categories:admired technological objects and archi-tectural objects inspired by them,concepts(function,truth,freedom,objectivity,unity,and power),standpoints(rationalism,romanticism,optimism,and determinism),and benchmarks of legitimation(ideology,history,scientific nature,everyday aesthetics,and sublimation of technology).These results were then combined to identify eleven significant discourses of techno-aesthetics.     

Medical aspects of compressed air tunelling: Background and present state of the art

The author traces the history of compressed air tunelling from the medical perspective. He describes the phenomenon of decompression sickness and attempts that heve been over the years to ameliorate the effects of decompression, e.g. the split shift. Also described is the development of decompression tables, beginning with the 1908 Haldanian schedules and progressing to the Washington State tables, the Blackpool tables, and the new Milwaukee tables. The author discusses the state-of-the-art research on decompression sickness, based in part on his own experience in treating compressed air tunnel workers in Milwaukee, Wisconsin (U.S.A.); and describes the process by which new decompression tables have been developed. The article concludes with an examination of oxygen decompression methods, and regulatory and institutional impediments to implementing these methods.     

公路建设项目水土流失危害与原因分析

简要阐述了我国"十五"期间公路建设项目发展概况,对公路建设所造成的水土流失危害进行了总结,并对公路工程建设特点及其所造成的水土流失原因进行了深入剖析,旨在为我国公路建设过程中生态环境保护提供理论依据.     

Wind loads on low-rise buildings: a review of the state of the art

This paper refers to the most recent research on wind loads on low-rise buildings. Novel measurement techniques and methodologies are reviewed, and selected experimental results from various studies are presented. Particular emphasis is given to works aimed at the formulation of codified data, i.e. results appropriate for incorporation into design standards and codes of practice. Only either full-scale studies or those done under conditions simulating the earth's atmospheric boundary layer have been considered. Comparisons between full-scale and laboratory results are discussed. Areas requiring additional research and analysis are identified.     

Soil/cement as a walling material—II. Some measures of durability

In the first paper a full factorial experiment designed to investigate changes in strength and strain characteristics was discussed. The main factors in the experiment involved changes in soil type, cement content and compaction pressure. This paper discussed the results from the same experiment using two measures related to durability as criterion variables. The first measurements recorded were of the initial surface absorption values and the second from a simplified freeze/thaw cycle test.     

Soil/cement as a walling material—I. Stress/strain properties

The properties of soil/cement vary not only with changes in soil type and cement content but also with the compaction pressure. While the effect of compaction pressure is widely recognized as affecting the properties of the material, rarely has it formed part of a comprehensive investigation. Previous published work has also concentrated almost exclusively on ultimate strength. This investigation was designed as a full factorial experiment using soil type, cement content and compaction pressure as the main factors with not only ultimate strength but also measures of strain and modulus as criterion variables.