振动焊接工艺

振动焊接工艺由大连理工大学、哈尔滨大学和海伦振动时效设备共同开发的振动焊接工艺填补了我国这一领域的空白。振动焊接是在金民焊接的过程中对被焊件施加振动处理的一项焊接工艺，能最大限度地改善焊接质量。经实验证明，振动焊接有以下优点：在焊接过程中施加振动，使...     

浅析监理人员对热力管道焊接的直接目视检查

分析热力管道焊接的监理的重要性,将热力管道焊接作业分为焊接作业前准备、焊接过程及焊接完工后三大环节,并逐一探讨热力管道焊接的监理要点,旨在为热力管道焊接监理工作提供思路和启发。     

钢结构产品焊接工序的质量控制

本文通过对广州内环路钢箱梁制作过程进行分析，以影响钢箱梁制作质量的关键工序——焊接工序为控制工序，分别从焊接前、焊接过程中、焊接后三个侧面对其质量控制进行了较为系统的阐述，具有较强的可操作性和实践意义。     

汽车制动蹄自动滚凸焊机

汽车制动蹄自动滚凸焊机该机主要用于大、中、小型汽车制动蹄和拖拉机、农用三轮车的制动蹄的滚凸焊焊接。转胎设计独特，焊接过程及胎具的转动全部由计算机数控控制，自动化程度高，焊接效率高，焊接过程中直板直接滚压为弧板，一次成型，焊接质量高；通过改换转胎也可进...     

焊接温度对木塑窗扇热熔焊接强度的影响分析

利用四位热熔焊接机对木塑窗扇进行热熔焊接实验,所用窗扇型材是由36%的塑粉（PE）、60%的木粉及偶联剂、抗氧化剂等挤出而成。在焊接过程中,影响热熔焊接强度因素较多,本次试验重点考察焊接温度对窗角焊接的影响。在完成焊接后,通过对木塑窗扇角强度的测试,进行单因素方差分析,并观察焊接接口,结果证明温度对焊接强度具有显著的影响,在240~280℃范围内可实现该木塑窗型材的焊接,理想焊接温度为260℃左右。     

带锯条对焊机的微机控制

带锯条在焊接过程中,容易产生某些质量问题。为解决这些问题,使带锯条的焊接质量达到统一标准,并使带锯条的焊接向自动化迈进一步,本文提出由微机进行控制的电路。给出了微机控制系统的硬件电路图,并阐述了它的部分工作原理。     

浅析液压挖掘机小臂的焊接方式

以部件机器人的结构和特点为基础,探究部件机器人对液压挖掘机小臂的定位与焊接技术。液压挖掘机小臂焊接技术由手工方式向自动化的方向改革发展,成为焊接技术领域新的发展趋势,其设计思想和整改方案,都显示了自动化技术的进步。部件机器人在工作的过程中,仍然存在着一些缺陷和不足之处,在推广运用部件机器人的过程中,需要不断地实践与优化,降低工程机械领域工人的劳动强度与劳动风险。     

锅炉生产中的焊接质量控制

根据锅炉生产的过程,对锅炉的焊接质量的控制进行了详细的阐述。     

定位焊在焊缝质量中的控制

定位焊作为焊缝中的一部分,其焊接质量的好坏将直接影响整条焊缝的质量,而在现实生产过程中定位焊却常常被忽视,就如何保证定位焊的质量进行了分析,总结了保证定位焊焊接质量的具体措施。     

技工学校焊接专业一体化教学模式探索

焊接专业一体化教学应从教学计划、教材设计、教学大纲、教学过程、教师资质以及教学环境等,实现以职业技能作为导向的专业化、一体化和综合化三者的有效结合。文章分析一体化教学推行的必要性,对焊接一体化教学方法进行了探讨。     

坚持和完善森林资源管理制度 保障和促进林业持续快速发展

概要阐述了森林资源在维护生态平衡、促进可持续发展中的重要作用,简要分析了当今全球和我国森林资源状况,全面总结了建国以来我国森林资源管理取得的成绩和经验,深入揭示了当前我国森林资源及其保护管理存在的问题和原因,系统介绍了我国森林资源管理的基本政策和制度。按照《中共中央国务院关于加快林业发展的决定》要求,对今后一个时期我国森林资源管理的思路、目标、任务提出了一些设想和建议。     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Short-term Effect of Thinning on Pinus sylvestris Damage and Sporulation Caused by Cronartium flaccidum

The short-term effect of thinning on cronartium rust on Scots pine ( Pinus sylvestris L.) was investigated in a stand of Scots pine (artificially seeded and in the pole-stage) severely infected by the stem-rust fungus Cronartium flaccidum (Alb. & Schwein) G. Winter. The disease rate (the number of old and fresh infections) was recorded before thinning, after which all trees with a resin-top as well as all individual branches with sporulating lesions were removed from the thinned plots, while the comparison plots remained non-thinned. The numbers of sporulating lesions were recorded on the plots annually for 2-5 yrs after thinning. Thinning had no significant short-term effect on the year-to-year relative number of sporulating lesions. The relative number of sporulating lesions, however, increased in both thinned and nonthinned trees, varying significantly from year to year. Thinning had no significant effect on the year of formation of the shoot bearing annual sporulating lesions, the duration of sporulation or the growth of the fungus along the infected shoot in perennial lesions during the first 5 yrs after the treatment.     

森林冠层结构与功能及其时空变化研究进展*

林冠是森林与外界环境相互作用最直接和最活跃的界面层 ,同时 ,它本身又承载了森林生物多样性的主体部分。森林冠层研究的方法和技术在近些年取得了长足发展 ,从而促进了有关林冠结构与功能的研究。这些研究深化了人们对于林冠结构与光能截获以及群落干物质积累之间关系的认识 ,同时 ,对于森林冠层的物质循环和能量传输以及冠层内各营养级之间相互关系动态也有了更为深入的理解。考察森林冠层的结构与功能及其时空变化是深入理解整个森林生态系统的格局、过程及其运作机制的重要基础。     

Concentrations of Cadmium,Lead and Mercury in Different Soils in Two Swedish Forest Catchments

Accumulation of cadmium (Cd), lead (Pb) and mercury (Hg), as affected by organic matter content, pH of different soil compartments and the physicochemical properties of each metal, was studied in different soil types within two forested catchments of the Norway spruce (Picea abies - Vaccinium myrtillus) type. Independent of soil type, the highest metal concentrations were found in the organic layers of the soil, usually in the surface soil. The concentrations in the upper part of the mineral subsoil were about one-fifth to one-tenth, or less, of those in the organic surface soil. Concentration maxima in the B-horizon were more pronounced for Cd and Hg than for Pb. When comparing soil types, the highest concentrations of Cd were found in the less acidified fens in the discharge area, while for Hg and Pb the highest concentrations usually occurred in the mor layer of the well-drained Podzols. For all metals, the soil types with the largest accumulation had concentrations up to 2-3-fold higher in the organic layers than those with the smallest accumulation.     

Photosynthetic Characteristics of Ash and Larch in Mixture and Pure stands

IntroductionDuringthepasttwodecades,studieshaverevealedthatgrowingash(Fnainusmandshurica)andlarch(LarlksPP.)togetherinaproperwaycanincreasetheproduc-tivityQfthestandsI"'}'-'].Theyieldimprovementmechanismsattributetotwoaspects,i.e.,theabovegroundandundergr…     

用碘结晶法测量针叶树材的微纤丝角

采用碘溶液和氢氧化钠两种溶液的混合液处理针叶树材管胞弦壁切片，并用干燥法脱除切片胞壁水，对碘结晶法测量木材微纤丝角的方法进行改良．结果表明，切片的木素脱除干净彻底，次生壁微纤丝之间易形成空隙，有利于碘离子进入其中形成碘结晶，可清晰地观察到微纤丝的走向，有利于有效而准确地测量微纤丝角，与改良前进行比较，具有省时省力，节约经费的优点．     

Improvement of dispersing property of sodium sulfite-formal-dehydeanthraquinone pulping effluent by treatment withCoriolus versicolor

A strain of the fungusCoriolus versicolor was inoculated periodically into potato dextrose agar (PDA) slants containing the effluent to enhance the natural ability to grow in the effluent. The acclimated strain grown in the 50% effluent-containing PDA slant and the original strain were employed to treat the effluent. The acclimated strain could grow in a higher concentration of the effluent than the original unacclimated one. Both the original and acclimated strains improved the dispersing ability of the effluent, especially the acclimated strain because of its higher laccase secretion. The dispersing ability of the SFP effluent was improved to a level comparable to a commercial lignosulfonate product because it was strongly polymerized by the fungus. During the fungal treatment, more than 50% of the sugars were removed from the effluent, thereby increasing the purity of the SFP lignin product.This work was presented at the 48th annual meeting of the Japan Wood Research Society, April 3–5, 1998, Shizuoka, Japa     

浅议野生动物所有权

野生动物所有权是所有权的一种,它与其他所有权的区别在于客体的不同。文章阐述了野生动物的内涵,分析了野生动物的分类和野生动物与野生动物资源的区别。在明确野生动物含义的基础上,提出了野生动物所有权的概念,深入论述了野生动物所有权与野生动物资源所有权的差异和联系,并对野生动物所有权的主体、客体、内容进行了分析。     

Persistence of herbicides in forest nursery soils

The persistence of the four herbicides atrazine, hexazinone, lenacil and linuron was studied in forest nursery soils. The adsorption capacities of the soils for the chemicals were described by the distribution coefficients kj and k_oc. Due to the low content of organic matter in the soils the k_a‐values were low, in several cases being <1 for hexazinone. Hexazinone also had the lowest k _oc‐value (30) while the other substances had k_oc ‐values within the range 200–400. In some cases hexazinone showed great mobility under field conditions. The formula c=c_o‐kt^1/2 was used to describe the disappearance of the herbicides from the various soils. The rate of degradation of the four herbicides correlated well with the rate of respiration in the same soils in laboratory experiments, and for linuron reasonably well also in field experiments. In the field experiments the herbicides penetrated the top soil layer. In the subsoil the risk of further transport downward to the drainage system or ground water increased, especially for hexazinone. Linuron as well as the fungicides maneb and tolylfluanid suppressed the decomposition rate of hexazinone in laboratory experiments.