CASIO fx-4500P/4800P计算器在伐倒木区分求积中的应用

对CASIO fx-4500P/4800P 型计算器在伐倒木区分求积中的应用进行了阐述.给出了按不同的区分方法和求积算法计算树干材积的方法、程序及相应的材积误差率.列出了程序流程及清单,并对其使用作了说明.     

编制photoshop7.0外接程序辅助计算林业调查及规划设计地形图勾绘小班扫描图面积

详细介绍了利用windows API功能调用,编制photoshop7.0外接程序,实现林业调查及规划设计中计算地形图勾绘小班扫描位图面积的方法。     

木家具常用榫结构受力分析与计算

家具的结实与稳定程度,一直是用户选购家具时所考虑的主要因素,同时也是衡量家具质量优劣的主要标准．对家具几种常用的、易受损坏的榫接合形式在承载荷过程中所受的各类力进行了分析;并在此基础上给出了对所受各类力进行量化计算的数学模型     

Possibilities for energy wood procurement in north-west Russia: Assessment of energy wood resources in the Leningrad region

Abstract

Methodology to assess the potential for energy wood procurement in Russia is described in this article and applied to the Leningrad region. Wood from thinnings, logging residues, non-industrial roundwood and residues from sawmilling are considered as sources for energy production. Energy wood available in the region, based on the 2004 actual cut, is approximately 4 million m³. Nearly 86% of this is non-industrial roundwood and felling residues, and 14% is by-products from sawmilling. Almost two-thirds of the non-industrial roundwood and felling residues are in cutting areas and one-third is in central processing yards. Deciduous tree species (birch and aspen) dominate in energy wood, representing about 65% of the total amount of felling residues and non-industrial wood. It is possible to intensify utilization of forest resources and thereby also to increase the use of wood in energy production. The total amount could be 54% higher if the allowable cut was fully utilized and 124% higher if thinnings were also utilized completely. There are, however, significant intraregional differences, as the current rate of utilization of forest resources varies in the region.     

广州南香山水库森林水文季节变化研究

为了提高森林水文研究过程中数据采集的精确性,应用现代测绘技术,包括水准测量、全站仪三维坐标测量、GNSS 卫星测量及测深仪的水深测量等,研究了广州南香山水库的库容变化规律,反演水库上游森林径流。研究结果表明：南香山一年内的降雨量分布出现类似双波浪形的变化,波峰出现在5月份和8月份,波谷出现在1月和10月;降雨量与库容增量存在线性关系,相关系数为0.9152;地表径流的大小主要与植被类型,土壤水分的饱和度及地形有密切关系。相比传统的测量方法,现代测绘技术更精确地反映了广州南香山地区森林水文的变化规律。     

果蔬热物性的研究与比较

利用测量热物性的实验装置与计算模型,对多种果蔬进行实验数据的研究比较,找出较为准确的方法,通过研究发现式(2)(6)和式(17)较好,并为今后果蔬热物性的研究提供理论基础.     

A Study Transient on Predictive Calculation Method of on Underground Ventilation Network

The authors developed a computer program of transient predictive calculation method on underground ventilation network. The program approximated a field data set of seasonal cyclic changes of air Temperature and humidity at the inlet to the sine curves, and included sensible heat conduction from rock to air current. The temperature of rock around and airway was calculated by finite difference method. The prediction method can be used to calculate the variation of flow rates, temperatures and humidities of air flow in the airways along underground network.     

改进遗传算法在环状管网水力平衡计算中的应用

标准遗传算法不擅于局部微调,在标准遗传算法的基础上,利用传统的优化方法中坐标轮换寻优方法对个体进行局部微调,寻优能力明显提高。把该算法用于环状管网水力平衡计算,计算结果精度较高。     

水环境容量的研究

如何将人类活动控制在水资源、水生态环境的承受范围之内,已成为实现人类可持续发展的核心问题之一。阐述水环境容量的定义、内涵、基本特征和类型,系统分析国内外对水环境容量研究的现状,并介绍水环境容量的计算方法,为今后水环境容量的研究提供一定的理论依据。     

淤泥对弧形钢闸门启门力影响的计算方法

为了估算泥沙淤积对弧形钢闸门启门力的影响,提出了一个计算公式.该公式将门前淤泥考虑为由粗细颗粒组成的宾汉体,同时考虑了泥沙附着力的力矩、梁格中附带泥沙重力的力矩、转动铰摩阻力的力矩、止水摩擦力矩、下吸力的力矩以及闸门重力和外加重力的力矩对弧形钢闸门启门力的影响.并利用该公式计算的弧形钢闸门启门力和西洱河二、四级电站泄洪闸门的实测资料进行对比得出：在门前泥沙淤积厚度较低的情况下,弧形钢闸门的启门力矩主要由闸门重力和外加重力决定,但是由泥沙引起的启门力矩变化也是不容忽视的,是导致闸门开启困难的影响因素之一,因此在设计过程中应充分考虑泥沙淤积对闸门启门力的影响,制定出合理的操作和维护方案,以防止闸门启闭困难情况的出现;该公式在计算门前有泥沙淤积情况下的启门力时,其计算精度能够满足工程实际需要.