北京八达岭人工油松林地表枯死可燃物负荷量研究

地表枯死可燃物负荷量多少是森林火灾发生的基础。调查八达岭林场不同地形条件下油松林地表枯死可燃物和林分因子,取得42块样地资料;用线性相关分析法对各因子与地表枯死可燃物负荷量进行分析,平均树高、坡度和海拔与对应负荷量有显著线性关系;应用多元线性回归中的逐步回归剔除法,建立了估测模型,除平均胸径外,平均树高、密度、郁闭度、海拔、坡度被引入,经检验回归显著,该估测模型可用于其它油松林地表可燃物负荷量估测。     

多重集合的运算研究与应用

集合是现代数学中最基本的概念之一,并已深入到各种学科和技术领域中.而作为集合概念扩展的多重集合概念,却少有应用.通过对多重集合进行系统研究,提出了多重集合的包含、相等、多重幂集,以及多重集合补集等相关概念和运算,建立了多重集合完善的理论体系,并给出了多重集合在古典概率中的应用.为进一步研究多重集合在各种学科和技术领域中的应用打下了良好的基础.     

基于多指标区间数关联分析的相对隶属度方法

针对具有区间数的多指标决策问题,借鉴一种逼近于理想点(TOPS IS)分析方法的思想,采用区间数灰色关联度的计算方法,对正、负关联度,利用相对隶属度方法对多方案进行排序,给出了解决区间数多指标决策问题的计算步骤.本文将整个评价方案看作一个整体来寻求正、负理想方案,该方法避免了区间数难以排序的问题,具有可理解性和可操作性.最后给出实例以验证该方法的有效性和实用性.     

硬岩抗剪强度参数的最优化确定法

为了减小岩工程分析计算的工作量和节约研究经费,须利用有限的室内实验样本的测定值,通过对有限实验样本数据的回归分析整理,确定岩石抗剪强度参数c、φ,进而估计岩体的抗剪强度c、φ.由于试验方法、试验条件等有一定局限性,因而,岩石力学参数的试验结果具有一定的不确定性.其不确定性包含随机性和模糊性.而用传统的数理统计方法处理岩石样本值,显然是不合适的,只有通过寻求最优的数学回归分析方法,来处理相关试验结果.笔者通过对硬岩变角度剪切实验和常规三轴压缩实验的数据回归分析,得到利用最小二乘法的抛物线回归分析结果和随机-模糊回归分析结果比较符合.因而,为了优化计算结果而又避免繁琐的计算,通常可以采用最小二乘法的抛物线回归分析计算代替随机-模糊回归分析相关结果.     

辽东山地混牧林经济分析

混牧林业是森林生态系统开发利用的一个重要组成部分。发展混牧林业直接关系到山地农村经济发展与环境改善和农民收入的提高。通过对辽东山地主要树种的林牧结合经营模式的实地观察调查,并采取回归分析和净现值计算,结果证实:混牧林业可以直接提高森林资源经营的经济效益,并且有较高的经济阈值,但对林分蓄积增长有负面影响,应适度控制载畜量和禁止在幼林下放牧。     

An analysis of a silvopastoral system for the marginal land in the Southeast United States

Almost 20 million acres of non-forest cropland in the South can be classified as marginal. Demand projections for forest products call for a 40 percent increase by year 2030. Recent regenerated tree acres lag behind harvested acres. Multiple land use practices combining trees and grazing adjust cash flows forward mitigating negative flow period associated with conventional forest production. Profit opportunities for private, non-industrial landowners can be increased by ranking inputs in order of changes to net present value(NPV). A sensitivity analysis of an agroforestry scenario, including trees, beef cattle, and pasture, allows producers to concentrate management efforts where returns are greatest. Model results show greatest returns to NPV was realized from improvement to Chip-N-Saw income. The least increase in NPV came when the cost of control burns was changed.     

外界生态因子对油茶品质影响的研究

对21个地区58个油茶物种(或优良品种)进行了含油率、脂肪酸组成、碘值和粗蛋白质等化学品质的分析。通过选取14个不同地区的普通油茶(Camellia oleifera Abel)的品质与19个生态因子进行多元线性逐步回归分析,揭示了不饱和脂肪酸含量与纬度成明显的正相关;种仁蛋白质含量与8、9月份的降雨量呈负相关的趋势。品质之间的相关分析表明:不饱和脂肪酸含量与蛋白质含量存在明显的负相关关系;不同物种之间,其不饱和脂肪酸含量与果实的大小成负相关。     

Height–diameter equations for boreal tree species in Ontario using a mixed-effects modeling approach

Height–diameter relationships based on stand characteristics (trees/ha, basal area, and dominant stand height) were investigated for balsam fir, balsam poplar, black spruce, jack pine, red pine, trembling aspen, white birch, and white spruce using data from permanent growth study plots in northern Ontario, Canada. Approximately half the data were used to estimate model parameters with the rest used for model evaluation. Multiple Chapman–Richards functions with parameters expressed in terms of various stand characteristics were fit to determine the best models for predicting height.     

闽东桉树品系造林效果综合评价研究

选择福建省有一定栽培面积的7个桉树品系,在永泰县的三个海拔带分别采用随机区组,3次重复的试验设计,运用多目标决策原理,进行综合评价研究,结果表明在永泰山地造林综合指标表现最好的为尾赤桉201;其次为尾园桉184、尾巨桉3229、赤桉9号、巨尾桉C6、;比较差的为巨桉A5、柳窿桉9号。在本地区,包括整个闽东Ⅱ08桉树引种小区,发展桉树宜提倡使用尾赤桉201。     

Assessment of wood surface roughness: comparison of tactile roughness and three-dimensional parameters derived using a robust Gaussian regression filter

Japanese oak and Japanese beech were sanded by hand with abrasive papers of varying grit number. Two three-dimensional parameters selected to characterize their surface roughness – one parameter for the distribution of roughness-profile peaks and the other for the relative area of the roughness-profile peaks above the threshold height – were compared against tactile roughness. The parameters were obtained from roughness profiles as determined by a robust Gaussian regression filter (RGRF) using seven cutoffs. The RGRF filtering process was adjusted specifically for the evaluation of wood surface roughness. Except for a cutoff wavelength of 0.25mm, the RGRF lent itself well to the determination of roughness profiles. No distortion of roughness profiles occurred around deep valleys, and there was a good correlation between the parameters and tactile roughness.Part of this study was presented at the 2002 Kansai Branch Office lecture meeting of the Japan Society for Precision Engineering, Kyotanabe, August 2002