路线平面曲线定测极坐标原理计算程序

文章介绍适用于PC-E500计算器使用的、采用TRUE BASIC语言编制的路线平面线型定测计算程序,论述程序的基本结构、数据输入与结果输出及使用方法,并举例说明源程序的应用。     

具有缓和曲线圆曲线的二种测设方法

本文介绍具有缓和曲线圆曲线的2种测设方法:a.分布测设缓和曲线和圆曲线;b.在直缓点或缓直点1次设站连续测设近端缓和曲线和圆曲线。同时给出2种测设方法的切线支距法和偏角法的公式。     

道路圆曲线平面详测的又一种新方法

根据切线支距法计算曲线坐标 ,提出了在交点架设仪器应用极坐标施测方法进行曲线测设的方法     

PC—1500在正弦支距法中的应用

在公路测设中，用切线支距法与弦支距法结合完成曲线测设，并用ＰＣ－１５００机辅助计算，能简化计算过程及正确完成曲线测设。     

PC─1500在正弦支距法中的应用

在公路测设中，用切线支距法与弦支距法结合完成曲线测设，并用ＰＣ—１５００机辅助计算，能简化计算过程及正确完成曲线测设。     

林区道路复曲线施测新方法

本文通过一系列数学推导，得出了复曲线上待测点及任意测站点的坐标公式，使极坐标法施测复曲线成为可能，为在不利的环境中施测复曲线提供了一个既简便又灵活的新方法。     

线形诱导标志在带有缓和曲线的平曲线上的设置

在国内外关于线形诱导标志的研究基础上，按照切线支距法，对我国山区高等级公路含有缓和曲线路段的线形诱导标志设置进行了探讨。     

林区道路复曲线施测新方法

本文通过一系列数学推导,得出了复曲线上待测点及任意测站点的坐标公式,使极坐标法施测复曲线成为可能,为在不利的环境中施测复曲线提供了一个既简便又灵活的新方法。     

基于Android的角规测树及数据处理软件的设计与实现

利用智能手机摄像头和虚拟角规原理,在小米3和魅族MX2两款手机上实现了虚拟角规,并将其集成在一款Android野外测树及数据记录处理应用程序中,利用手机触摸屏实现了在调查数据散点图上画随手曲线的功能,为小班调查野外作业提供了便捷的工具,同时,还实现了与该款软件相匹配的一款桌面应用程序,方便后续内业数据的汇总处理。     

掌握根腐规律提高造材效率

本文通过对有干基根腐缺陷的原条的统计与分析，提出了“一次截断法”，并在实际生产中得到应用，提高了造材效率。     

松毛虫病毒增殖新方法

大型围栏和开放式围栏是病毒增殖的两种新方法。大型围栏用塑料薄膜制成 ,长12～ 30m ,宽 1 8～ 2 5m ,四周用木桩固定 ,栏内设置悬挂松枝的桩或木杆 ;开放式围栏是用塑料薄膜围住一片低矮林分 ,面积为 2 0～ 4 0 0m2 。栏内幼虫投放量为 4～ 6kg/m2 ,感染浓度为(1～ 5 )× 10 7PIB/mL ,接种病毒后 13～ 15d回收感病虫     

Modeling Branch Length and Branch Angle with Linear Mixed Effects for Dahurian Larch

In this study,the sample data was based on 2 190 branch length and angle samples of 30 trees from dahurian larch（Larix gmeiinii） plantations located in Wuying Forest Bureau in Heilongjiang Province.The stepwise regression techniques were used to develop branch length and branch angle models:BL= b₁ + b₂ DINC + b₃ DINC² + b₄ DBH·DINC²,BA = b₁ + b₂ DINC + b₃ DINC² + b₄ DBH·DINC.Then,the developed models were fitted using linear mixed-effects modeling approach based on LME procedure of S-PLUS software.Evaluation statistics,such as AIC,BIC, Log Likelihood and Likelihood ratio test were used for model comparisons.The results showed that the branch length and branch angle models with parameters b₁,b₂,b₃ as mixed effects showed the best performance.Exponential and power functions were incorporated into mixed branch length and branch angle model.The addition of the exponential and power functions significantly improved the mixed-effects model.The plots of standardized residuals indicated that the mixed-effect model with exponential and power functions showed more homogeneous residual variance than the mixed-effects model.Validation confirmed that the mixed model with calibration of random parameters could provide more accurate and precise prediction.Therefore,the application of mixed model not only showed the mean trends of branch length and branch angle,but also showed the individual difference based on variance-covariance structure.     

Practical methods for non-destructive measurement of tree leaf area

In an agroforestry context, the knowledge of leaf area is an important parameter to take into consideration because tree foliage shades the intercrop. Single leaf measurement (for example leaf length and width) is a widely used method to estimate leaf area in a rapid non-destructive way. In this study, the objectives were to estimate the leaf area of different leaf sizes and shapes for Acacia mangium Willd. (Mimosaceae), Tectona grandis L. (Verbenaceae), Hevea brasiliensis Muell.-Arg. (Euphorbiaceae), and Swietenia macrophylla King. (Meliaceae) Indonesian agroforestry trees. In order to characterise leaf area in field conditions a digital photograph method was used. Leaf length was measured in order to build relationships between leaf length versus actual leaf area. Additional measurements obtained from the digital pictures such as lamina width, number of leaflets, leaflet length and width were recorded in order to test the benefit regarding leaf area estimation based only on the leaf length model. The combination of these different linear leaf measurements led to various degrees of precision of leaf area estimation. The different models can then be chosen according to a compromise between the accuracy of leaf area estimation and the time allocated to field measurements.     

Assessment of Three Methods for Estimating Abundance of Ungulate Populations

InttoductionEStimahonofabundsnceisabasictaskinanalytingthe~csOfwildlifePOpulahon.TheinformahononpoPulahonabundanceisalsocrucialtoscienhficman-agementofwildlife.Toeshmatethedensity,theaccu-rnyofamethodisanimPOrtantconsiderahon.Ungulatesarerelahvelylargeint…     

基于线性混合模型的落叶松人工林节子大小预测模型

以黑龙江省东北部落叶松人工林为研究对象,应用19块标准地中95株解析木(每块标准地选取5株)的节子剖析数据,采用线性混合效应模型理论建立落叶松节子各因子(节子直径、着生角度、长度)的预估模型。结果表明:节子直径、着生角度和长度都随着树木胸径的增大而增大;节子直径随着着生高度的增大先增大后减小;节子角度随着着生高度的增大而逐渐减小;节子长度随着直径的增大而增大。与固定效应模型相比,考虑混合效应所建立的节子大小预测模型其参数估计更为准确,残差分布更加均匀,模型拟合精度明显得到提高(R2约提高了0.3)。独立样本的检验结果表明:各模型的预估精度均在90%以上,说明所建模型可以很好地描述落叶松人工林节子变化规律。     

毛白杨优良无性系(新品种)材性测定研究

按生长性状预选出毛白杨１３年生１０个无性系用于材质测定。试材取自北方大兴县测定林,每无性系在３个重复中各抽样１株,伐倒取样,分析表明,毛白杨无性系间纤维长度,宽度和长宽比差异极显著,重复率依次为０．７７７,０．５３７和０．６７６;木材全年密度,早材密度和晚材密度差异极显著,重复率依次为０．５３６,０．５１４和０．４２９。     

利用经纬仪测量水平距离和高差的新方法

介绍了利用经纬仪测量竖直角和中丝读数，推导出两点间的水平距离和高差的计算方法，该法与常规视距测量相比，推导严谨，实测精度较高，且不受地形限制，方便快捷。随着高精度的电子经纬仪的开发应用，可以大大提高本方法的测量精度，甚至在一定精度范围内可取代全站仪进行所有的功能测算。     

Effects of strand length and layer structure on some properties of strandboard made from bamboo

Strandboard panels were experimentally produced from moso bamboo (Phyllostachys pubescens) using various strand lengths and layer structures to evaluate the effects of manufacturing parameters on panel properties. The strandboard was fabricated in a laboratory using diphenylmethane diisocyanate (MDI) resin and laboratory-made strands of four lengths and four different structures. Strand alignment distributions and concentration parameter (k) values were greatly affected by strand length. A linear correlation was found between the value of k and the modulus of rupture (MOR), with correlation coefficients of 0.81 and 0.93 for unidirectional boards and three-layer boards, respectively. This correlation may be used to predict the strength properties of boards. Bending properties were significantly affected by both the strand length and the layer structure of the bamboo strandboard tested. Elasticity data from unidirectional boards and random boards can be used to predict the elastic properties of three-layer boards. The linear expansion (LE) of the random boards increased with decreasing strand length. The difficulty in mat forming and resin distribution for longer strands could cause deviation in modulus of elasticity (MOE) and LE, especially in strand lengths around 80 mm.