斜预应力空心板施工裂缝控制

通过对预应力空心板施工裂缝的调查总结,对斜预应力空心板施工裂缝产生的原因进行了分析,并提出了制定预防裂缝的具体措施。     

桥梁空心板梁底开裂成因及其处理防范措施

针对某空心板桥梁在施工中出现锚端裂缝的问题,结合施工经验,分析裂缝产生原因,指出裂缝对梁承载力和正常使用的影响,提出了具有针对性的处理防范措施。     

路基填方过度碾压开裂的力学分析

结合兰州市北滨河路银农段路堤填筑施工中出现的大范围的表层裂缝,选取合适的应力函数进行力学分析,从而找到了产生这种裂缝的力学机理,提出防止出现类似裂缝的措施以指导施工.     

混凝土冬季施工裂缝控制

混凝土进入冬期施工,受气温影响,属于裂缝多发期。文章分析混凝土冬期施工裂缝产生的特性及原因,提出了相应的控制措施。     

解析某水电站蜗壳施工中化学灌浆施工技术的应用

蜗壳施工是水电站工程施工中的重要环节,一般水电站的修建都需要混凝土蜗壳方面的施工技术为辅助,由于长期水力冲刷使混凝土施工中出现大量裂缝,在大多数工程中,采用化学灌浆作为处理裂缝问题的主要方法。结合某水电站使用化学灌浆进行处理裂缝的施工程序,对化学灌浆前所做的准备、施工工艺等进行了分析。     

"福胜大厦"地下室混凝土施工的控制裂缝技术措施

在高层地下室施工过程中,结构产生裂缝是一个相当普遍的问题,文章从材料和施工两方面提出了一些控制裂缝的有效技术措施。     

混凝土楼板裂缝的分析、控制和防治

本文时楼板裂缝产生的原因进行了分析,从裂缝原因、裂缝防治措施和处理等方面进行了论述,指出只要按规范进行设计与施工,即可使裂缝得到有效的控制.     

浅谈混凝土裂缝与施工

混凝土内出现的裂缝按深度的不同,分为贯穿裂缝、深层裂缝及表面裂缝三种。为了保证出现最少的裂缝,就必须在混凝土施工时掌握它的基本性能,并根据实际应用情况采取有效措施,以确保施工质量。     

论述混凝土裂缝形成的原因及防治措施

论述混凝土在施工中裂缝产生的几个重要因素。分析和总结裂缝产生的原因，强调了施工中所采用的几种防治措施。     

浅谈混凝土裂缝修补方法

混凝土在施工过程中要产生裂缝,本文分析裂缝产生的原因,提出了修补方法。     

Repair and strengthening of timber cantilever beams

This research aims to study the feasibility of repair and strengthening of timber cantilever beams used in historic buildings. It is conducted to investigate the feasibility of using different valid materials and techniques to repair and strengthen timber cantilever beams in new and historic timber buildings. The study is performed in terms of structural performance as well as historic and architectural values. An experimental program of several different materials and techniques is executed. The results are driven in terms of initial cracking load, crack propagation for the tested samples at different loading stages, deflection values, and failure load for each repaired or strengthened material and technique. The main variables are timber types (new and historic), repair and strengthening materials (steel plates, Glass Fiber Reinforced Polymer wrap, and Carbon Fiber Reinforced Polymer laminates), repair or strengthening techniques (near surface mounted and externally bonded system), and cantilever length (1000 and 1250?mm). Test results indicated that using steel plates, glass fiber wrap, and carbon fiber laminates increases the value of failure loads and decreases the deflection at both; repaired and strengthened timber cantilever beams compared to control beams.     

竹大片刨花板对竹材生物学特性的适应性

以云南四种典型材用丛生竹（龙竹、甜龙竹、黄竹和油勒竹）宏观构造、组织结构、主要物理力学性质和化学组份等竹材主要生物学特性的研究分析结果为依据,提出了竹大片刨花板的结构、制板工艺和设备与原料竹材生物学特性之间应有的适应性关系。继而,通过实验室系列化试验和工厂试生产,确定了竹大片刨花板的应有性能和最佳工艺条件包括竹大片刨花的最佳质量指标及其最佳制备条件。     

Comparative Study in Chemical Character and Fatty acid Compositions of Masked Civet''''s Fat and Nutria''''s Oil

IntroductionMaskedciVet(Paguma18vata),Mammalia,Viverridae,ismainlydiStributedinShanxi,Sichuan,Tibet,Yunnanprovinces,etc..Itsmeatisdeliciousandhasspecialflavor.Itiseasytoberaisedartificially,withhighproduCtivity.Nutria(MyocasterCOypus),Rodentia,Capromyidae,originatedinArgentina,Chili,etc.insouthAmerica.Itisakindofherbivoresfur-bearer.itsartificialraisinghassuchmeritsasdurablefurandlowcostandhighproduCtivity.MaskedcivetandnutriahavehigheconomicvalueandwideprospeCtofutilization.Atpresen…     

自然保护区合作管理(共管)理论研究综述

自然保护区合作管理自20世纪80年代末期开始逐步兴起,在资源管理中被广泛使用。文章介绍了共管的含义、共管实施原则、分析框架和评价指标。从公共部门和私有部门的互动模式、集体行动类型的不同、政府和资源使用者的参与管理方式三个方面论述了共管的模式。分析了政府和社区在共管实施过程中的作用,指出共管仍面临着分权不够、合作中的文化障碍、组织类型简单和信息交流不充分、社区参与能力和认识能力不足等挑战。     

Spatial patterns of Douglas-fir and aspen forest expansion

Spatial patterns, rates, and density of encroaching forests into adjacent grasslands have important implications for long-term land use management and resource planning. This study examines the effects of Douglas-fir (Pseudotsuga menzeisii) and aspen (Populus tremuloides) regeneration mechanisms on sucker and seedling spatial patterns, distance from adult trees, and density in encroaching forests. A total of 8,924 aspen suckers and 1,244 Douglas-fir seedlings were counted and mapped in 2,920 quadrats (5 m × 5 m) in 106 plots along a lower forest-grassland ecotone in the Centennial Valley, MT, USA. Sucker and seedling spatial patterns were analyzed using Morisita’s I index. Average sucker and seedling density per quadrat and distance from adult trees were estimated for each plot and compared between aspen-dominated plots and Douglas-fir-dominated plots using ANOVA tests. Aspen suckers were established in a clustered spatial pattern at a significantly higher density and a significantly shorter distance from the adult trees. In contrast, Douglas-fir seedlings were established in varying spatial patterns at a significantly lower density and a significantly greater distance from the adult trees. Forest encroachment into the adjacent grassland in the Centennial Valley is occurring in contrasting patterns and at varying rates and densities due to the difference in aspen and Douglas-fir regeneration mechanisms.     

气候因子对竹子生长的影响研究综述

竹子是集经济、生态和社会效益于一体的优良林种,是区域农村经济社会发展的重要资源和生态环境保护的重要屏障.温度、水分、光照、大气组分等的变化直接影响着竹子的生长发育和分布.该文从主要气候因子对竹子生物学特性、生态学特征及其分布和经济产出的影响研究现状进行了综述,提出了今后需要重点开展的相关研究内容.     

Modelling impacts of changes in carbon dioxide concentration,climate and nitrogen deposition on carbon sequestration by European forests and forest soils

Changes in the Earth's atmosphere are expected to influence the growth, and therefore, carbon accumulation of European forests. We identify three major changes: (1) a rise in carbon dioxide concentration, (2) climate change, resulting in higher temperatures and changes in precipitation and (3) a decrease in nitrogen deposition. We adjusted and applied the hydrological model Watbal, the soil model SMART2 and the vegetation model SUMO2 to asses the effect of expected changes in the period 1990 up to 2070 on the carbon accumulation in trees and soils of 166 European forest plots. The models were parameterized using measured soil and vegetation parameters and site-specific changes in temperature, precipitation and nitrogen deposition. The carbon dioxide concentration was assumed to rise uniformly across Europe. The results were compared to a reference scenario consisting of a constant CO₂ concentration and deposition scenario. The temperature and precipitation scenario was a repetition of the period between 1960 and 1990. All scenarios were compared to the reference scenario for biomass growth and carbon sequestration for both the soil and the trees.     

我国湿地保护管理现状与优化对策

我国湿地资源在全球占据重要地位, 在我国生物多样性保护与社会经济可持续发展方面发挥着重要作用。在总结我国湿地保护管理现状的基础上, 文中指出我国湿地保护管理方面存在着责权不清、管理机构不健全且有重叠、将湿地划为未利用地以及制度与机制有待完善等问题, 提出了优化我国湿地保护管理体制的建议, 以期为湿地相关立法提供依据, 并进一步促进我国湿地保护管理水平的整体提升。     

Socioeconomic research in agroforestry: a decade in review

Agroforestry research in academia and government and non-governmental agencies began by focusing on biophysical aspects. As this science represents a series of practices implemented by individual farmers, it requires in-depth social and economic analyses to assess economic feasibility of agroforestry systems, factors influencing the adoption of agroforestry, monitor the relevance and effectiveness of investigations, and guide future research efforts. This study presents literature dealing with socioeconomic issues in agroforestry research from interdisciplinary peer-reviewed journals, book chapters, and gray literature from 1992 to 2002. Over 500 publications were analyzed to determine relative dominance of geographical regions, types of analyses, agroforestry technologies, and socioeconomic issues. Trends were examined over time and by region. Overall, the body of literature exhibits an increasing trend toward regional and analytical diversity over time. Some deficiencies of regional and thematic nature were observed, which included underrepresented temperate regions and technologies such as riparian buffers, as well as only a small number of papers dealing with gender and property rights. These suggest opportunities for future investigations.     

竹纤维增强聚合物基复合材料性能及应用

植物纤维来源丰富，能耗低，被认为是最具前景的绿色可再生资源。竹纤维具有成本低、密度小、比强度高等特点，与其他材料组成的复合材料是一种资源节约型和环境友好型材料。文章概述了竹纤维的结构组成与力学性能，综述了竹纤维增强聚合物基复合材料(BFRP)的研究与应用现状，在此基础上提出了BFRP今后的研究重点，包括竹纤维化学组成、界面性能及生产工艺等，以期为发挥其优良特性、扩大其应用领域提供参考。