基于时延神经网络的木材干燥模型辨识的研究

木材干燥是一个复杂、多变的过程，传统的系统辨识方法很难建立一个理想的木材干燥模型。利用时延神经网络的特点，本文提出了基于时延神经网络的木材干燥模型辨识方法，并给出了辨识网络和结构。对辨识得到模型的仿真结果表明，利用时延神经网络所建立的模型是可靠且有效的。     

中国木工机械制造业的国际竞争力探讨

首先阐述了我国木工机械制造业的发展现状,然后运用迈克尔.波特的钻石模型对我国木工机械制造业国际竞争力的影响因素进行了深入分析,最后提出提升我国木工机械制造业国际竞争力的几点建议。     

荒漠化程度评价高光谱遥感信息模型

本文用国产高光谱分辨率成像光谱仪系统数据对荒漠化评价建立定量化遥感信息模型。对荒漠化评价因子中的主要定量因子 (植被盖度、生物量和土壤含水率 )进行了定量反演 ;对难于进行定量计算的评价指标 ,先通过目视解译获得各因子的编码图 ,分别进行影像化后参加荒漠化程度评价遥感信息模型计算。通过每个像元都可获取全部评价因子的指标值 ,在现有的荒漠化评价方法的基础上 ,建立以像元为单位的荒漠化程度评价的定量化遥感信息模型并输出荒漠化程度分布图。结果表明 ,用高光谱数据定量反演荒漠化地区植被生物量、盖度和土壤含水率是比较可靠的。当反演区域内灌木和草地同时存在时多项式模型的精度要明显高于线性模型 ;当植被类型单一时 ,模型即为较高精度的线性模型 ,但模型的应用地域范围受到限制 ,只能分块进行计算。因此 ,在只有灌木和草地的区域用多项式模型反演会提高效率。土壤含水量的反演方法适合于地形平坦、植被比较稀疏的条件。但研究发现 ,基于土壤热惯量的含水量模型具有一定的抗植被干扰能力。荒漠化程度评价的遥感信息模型的精度主要取决于现有荒漠化评价的方法 (即评价指标是否科学合理、专家给定的权重和等级标准是否客观 )以及各指标数据的获取精度     

适于AFLP分析的澳洲坚果DNA提取方法

利用SDS法和改良CTAB法对澳洲坚果两个品种的基因组DNA进行提取试验,结果表明:SDS法与改良CTAB法提取的基因组DNA完整性都比较好,但SDS法获得的DNA含有较多杂质,不能被限制性内切酶消化,改良CTAB法提取的基因组DNA可以完全酶切,DNA质量符合AFLP分析的要求。     

“洛阳1号”日本落叶松良种选育研究

"洛阳1号"日本落叶松是从天然林分后代超级苗中选出的天然杂种无性系,造林13年树高、胸径达11.33 m和11.67 cm,比对照高69.4%和114.9%,表现出明显的前期速生性。2011年该品种通过河南省林木品种审定委员会审定,具有生长快、材质优、抗性强、适应性广的优良特性,是优良的造纸用材树种,适宜在海拔800 m以上山区推广栽培。     

Growth and yield prediction models for Acacia mangium grown in the plantations of the central region of Bangladesh

Acacia mangium is a very fast growing species belonging to the family Leguminosae that has been introduced in the plantations in Bangladesh for its faster growth and wide range of adaptability. The present study aimed at development of growth and yield prediction models for the species using simultaneous equation method. Models were selected for the species to estimate stand dominant height, stand diameter, stand basal area per hectare and total volume yield per hectare. Paired t-test, 45-degree line test, percent absolute deviation and biological principle of stand development were used for the validation of chosen models. The results suggest that the models derived were statistically and biologically acceptable and could be satisfactorily used for stands of Acacia mangium of ages 4–7 yrs based on a base age of 6 yr.     

贮木场选址模型的研究

建立了一个贮木场选址的数学模型，这个模型将动态经济评价方法，运输网络和贮木场选址有机地结合起来。     

王朗林区人工缺苞箭竹亚层数量特征及其模型

王朗林区人工缺苞箭竹亚层数量特征及其模型刘兴良，向性明（四川省林业科学研究院成都６１００８１）关键词四川王朗，亚高山暗针叶林，亚建群层，缺苞箭竹，大熊猫，仿真造林缺苞箭竹（Ｆａｒｇｅｓｉａｄｅｎｕｄａｔａ）是四川王朗林区亚高山暗针叶林下亚建群层的主要...     

Comparing the model forms estimating generalised diameter-height relationships in Tecomella undulata plantations in hot arid region of India

Four generalised diameter-height equations were developed and compared for pure and even-aged stands of Tecomella undulata in hot arid region of Rajasthan State in India. The data used to fit the equations consisted of 1 540 diameter-height observations collected from the plots laid out in uniformly stocked stands of varying age and density. The performance of four equations was tested by non-linear least squares regression and evaluated using different statistical criteria. Finally, these equations, with the same values of coefficients ob- tained during the fitting phase, were validated by an independent data set consisting of 854 diameter-height observations. Overall, equation （4） （Hui and Gadow function） was found to perform best for both the fitting data set as well as validation data set.     

Traditional fallows in Latin America

Traditional fallow systems of Latin America have not been extensively studied from either a socioeconomic or biophysical viewpoint. Only in the past decade have some of these systems — modified shifting cultivation in the Amazon, the bracatinga (Mimosa scabrella) fallow of southeastern Brazil, the babassu (Attalea spp.) system of the Amazon margins, and short bush fallows mostly for Phaseolus bean (the so-called frijol tapado) — received any attention. Over the past century, traditional cultivators have adopted several legumes such as Mucuna spp., Lathyrus nigrivalis, Canavalia spp., and Senna guatemalensis as green manures or managed fallows in food crop production systems, which have recently been the object of studies by social and biological scientists. Longer, monospecific fallows involving woody legumes have been studied to varying degrees. The legumes include Senna guatemalensis, Mimosa tenuiflora, and Gliricidia sepium. Systems in which crop production is alternated with animal grazing of secondary vegetation include the caatinga of Northeast Brazil, the espinales of Chile, the matorrales of northern Mexico, and the chaco of Argentina, Paraguay, and Bolivia. A classification is proposed depending on the nature of the species (woody or nonwoody) and their composition (mono- or multispecies) and land management (burned or not). Much work is still needed in more complete characterization, determination of economic importance and potential, understanding the relationships among components, studies of nutrient cycling, and verification of the effects of shorter fallow periods of these systems.This revised version was published online in November 2005 with corrections to the Cover Date.