柔性吊桥设计理论及其应用研究Ⅰ.福建省简易柔性悬索桥分析研究

在收集有关资料和调查研究的基础上 ,根据我国桥梁规范 ,对典型的简易柔性悬索桥主要技术参数及构造进行分析和评价。简述近年在简易柔性悬索桥理论设计和工程实践方面的成果 ,并结合省情展望其发展趋势     

Transitions in forest fragmentation: implications for restoration opportunities at regional scales

Where the potential natural vegetation is continuous forest (e.g., eastern US), a region can be divided into smaller units (e.g., counties, watersheds), and a graph of the proportion of forest in the largest patch versus the proportion in anthropogenic cover can be used as an index of forest fragmentation. If forests are not fragmented beyond that converted to anthropogenic cover, there would be only one patch in the unit and its proportional size would equal 1 minus the percentage of anthropogenic cover. For a set of 130 watersheds in the mid-Atlantic region, there was a transition in forest fragmentation between 15 and 20% anthropogenic cover. The potential for mitigating fragmentation by connecting two or more disjunct forest patches was low when percent anthropogenic cover was low, highest at moderate proportions of anthropogenic cover, and again low as the proportion of anthropogenic cover increased toward 100%. This fragmentation index could be used to prioritize locations for restoration by targeting watersheds where there would be the greatest increase in the size of the largest forest patch.     

节约型园林景观营造的类型及实践

总结了节约型绿地的设计理论及绿化工程的分类,并通过实践营造徐州市云龙湖珠山景观,以期为郊野公园的景观建设提供参考。     

21世纪中国竹产业可持续发展的历史机遇

林业跨越式发展是我国建设现代林业的重要途径，现代林业是跨越式发展战略的目标。以现代林业理论指导我国林业跨越式发展是我国林业健康发展的根本要求。因此，我们要深刻领会现代林业理论的内涵，以可持续林业理论为指导，从林业的多目标经营入手，采取多种经营方式，依靠科学技术进步，动员全社会力量，实现林业的跨越式发展。     

Predicting the humidity control capacity of material based on a linear excitation-response relationship

The Cb value is a useful parameter for estimating the humidity control capacity of materials. It is defined as the ratio of the range of variation of relative humidity in a steel box lined with the material of interest to that in an empty steel box, when sinusoidal temperature variation is applied. However, because it takes a long time to obtain the Cb values for materials at each temperature variation period, we developed an easier method based on a linear excitation-response theory to obtain the Cb values without measuring at each period. Japanese cedar was the material used in this study. The temperature excitation, a jump from a constant temperature to another constant temperature, was used to obtain the absolute humidity response. Under the assumption that the temperature excitation-humidity response relationship is linear, we were able to predict humidity variation to sinusoidal temperature variation at any period, and we obtained the Cb value for each temperature variation period. Predicted values agreed well with the experimental values. From this, it was found that the Cb value could be predicted without measuring the Cb value at each period over a long time. In addition, the peak time difference, which is closely related to the Cb value, could also be predicted in a similar manner.     

不同营养元素的施肥处理对马尾松近熟林木材基本性质的影响

研究了 4种不同营养元素的施肥处理对马尾松近熟林木材基本性质的影响。结果表明 ,在不同施肥处理后的同一年中 ,N、P、K、NPK施肥处理对木材管胞长、宽及基本密度的影响不同 ,同一施肥处理在不同年度中 ,对上述性质的影响亦异 ,总之 ,无明显变化规律。方差分析表明 4个施肥处理与无施肥处理的管胞长、宽及基本密度差异均不显著 ,生长轮宽度与管胞形态和基本密度都不显著相关。     

生态补偿关键问题的探讨

本文对生态补偿的定义、理论基础、类型、机制、评价方法进行了阐述,介绍了我国生态补偿的发展状况,并提出了完善生态补偿机制的建议。     

基于不同预处理的椴树木材基本密度近红外光谱估测及模型优化

【目的】木材的基本密度在木材质量等级评定中起着重要的作用,是木材分流及精细化利用的重要依据。利用近红外光谱技术,实时监测木材性质,掌握木材性质的变化,为进一步制定和改善林木培育方法提供理论依据。【方法】借助树木生长锥对椴树活立木取样,以椴树样品基本密度真值和近红外光谱数据为输入,分别通过卷积平滑、一阶导数和二阶导数预处理方法来实现近红外光谱数据的预处理,建立了基于偏最小二乘法(PLS)的椴树木材基本密度的近红外估测模型。【结果】在350~2 500 nm波段范围内,一阶导数预处理的椴树木材基本密度模型是最优的,校正集相关系数为0.964 8,校正均方根误差为0.002 7,验证集相关系数为0.943 2,预测均方根误差为0.003 3。在对近红外光谱数据进行去噪优化处理,构建椴树木材基本密度模型后,在500~2 300 nm波段范围内,一阶导数预处理椴树木材基本密度模型依旧最优,其校正集相关系数为0.987 1,校正均方根误差为0.001 6,验证集的相关系数是0.948 6,预测的均方根误差是0.002 1。【结论】选择特定的预处理方法,结合样本特征,建立椴树木材基本密度模型,可以显著降低建模成本,提高模型预测精度,快速测定椴树木材的基本密度。     

日本森林组合的作用及其基本属性分析

本回顾了日本森林组合制度的形成和发展过程，系统地阐述了森林组合的组织体系、运营机制、财务制度、业务范围等，在此基础上，对森林组合在民有林发展中的作用、森林组合的基本属性等进行了深入的分析和探讨。