Estimation of shear moduli of wood by quasi-simple shear tests

A quasi-simple shear test, which is the most direct method for examining the shear properties of sheet metals, has been applied to measure the shear moduli of wood. Buna (Fagus crenata Blume) with variously sized shear regions was used for the test specimens. Strain gauges were mounted in the center of the shear regions to measure the shear strains. The shear tests were carried out to determine the shear moduli in the radial and tangential planes. Apparent shear moduli obtained from the experimental results were corrected by finite element method (FEM) simulation of the shear region, where both shearing and bending are produced. It was found that the corrected shear moduli are roughly independent of test conditions, and their values are in good agreement with the data obtained from bending-shear tests. This suggests that the method employed here can effectively estimate the shear moduli of wood.Part of this research was presented at the 50th Annual Meeting of the Society of Materials Science, Osaka, May 2001     

PV聚氨酯密封胶在高寒地区水泥混凝土路面的应用

详细地介绍了PV聚氨酯密封胶在高寒地区水泥混凝土路面接缝养护上的应用情况，阐述了PV聚氨酯密封胶的施工工艺和施工方法，对接缝料的配比试验和施工工艺提出了相应的技术要求。同时，分析了使用该材料的经济效益，肯定了在高寒地区的可用性和可推广性。     

苗圃精细筑床机设计

林业苗圃筑床机是育苗生产全程机械化的基础设备,但该设备三十多年几乎没有任何改进.针对原有(传统)筑床杌在作业过程中存在的问题和现代育苗生产的需求,研制开发了新型的苗圃精细筑床机.介绍了苗圃精细筑床机的总体方案、总体结构及总体参数的设计,以及其关键部件的设计过程.     

参与式流域管理理念下的林业活动策略和成效——澳援青海林业资源管理项目林业活动

在中澳合作青海林业资源管理项目实施过程中,引进和应用参与式方法和流域管理的理念,进行林业活动的设计和实施。文章全面总结了项目开展的主要林业活动,介绍了项目取得的成效和经验。项目的成功实施,为林业资源管理带来新的理念、新的管理方法和新的技术,取得的经验和做法值得在今后的生态环境保护和建设中借鉴。     

PVC管道或砌护渠道输水与开沟灌溉相结合的造林方法及效果

开沟灌溉造林与大田平灌相比，具有总体用水量少，局部给水量多的特点，能够显著地提高灌溉效率，提高造林成活率和林木生长量。同时，利用管道和砌护渠道输水，可防止渗漏，提高水的利用率。     

内蒙古集通铁路防护林构建技术研究

本项研究根据集通铁路所处的地理位置及所受沙灾、雪灾、风灾、水灾四大灾害的危害特点．以DK328 500～DK338 500为试验示范区，在调查分析当地自然条件的基础上．对沿线立地类型进行了科学的剖析和划分。针对铁路安全运输生产的要求，采用多种造林技术措施，乔灌草相结合，阻固造封并举．迅速恢复沿线林草植被。     

Shear strength of beam splice joints with glued-in rods

Splitting failure in beam splice joints with glued-in rods parallel to grain in endwood subjected to pure shear is considered. A simple theoretical expression based on beam-on-elastic-foundation theory and quasi-non-linear fracture mechanics is presented for calculation of the joint strength. Tests were conducted on jointed beams in a four-point bending test setup in which the joints were located at the point of pure shear force. Hardwood dowels with a diameter of 12mm and a glued-in length of 120mm were used as rods, and various beam cross sections and dowel configurations were tested. The theory presented is found to agree well with test results in all cases in which the edge distance of the glued-in rods is relatively small. Some test results indicate that the theory may be conservative in case of large edge distances.     

连续平压热压机的进展

论述了发展连续平压热压机的背景、必要性以及国外同类技术的详细情况,同时介绍了我国目前研究连续平压热压机的现状和迫切性。     

地下防水工程渗漏水的修堵

作者结合实践,分析了地下工程渗漏水的原因往往是由于设计不合理及施工不规范而造成的,并提出了相应的防治措施。     

杉木小径材胶拼技术

杉木小径材胶拼技术以６－１２ｃｍ的衫木小径材为原料，通过制材、胶拼、干燥和加工等工艺，生产出较大规格的板方材，可代替杉木中、大径材用于家俱、建筑等行业。