为全面掌握林场森林资源数量与质量变化情况,促进林场森林资源高质量发展,采用2003-2020年广西国有维都林场森林资源规划设计调查报告数据,对林业用地、森林面积、森林蓄积、森林覆盖率、森林生长量、森林消耗量等49项指标分析森林资源...为全面掌握林场森林资源数量与质量变化情况,促进林场森林资源高质量发展,采用2003-2020年广西国有维都林场森林资源规划设计调查报告数据,对林业用地、森林面积、森林蓄积、森林覆盖率、森林生长量、森林消耗量等49项指标分析森林资源数量动态变化;并采用层次分析法在森林起源、森林结构、森林产能、森林健康、森林价值等方面综合评价森林质量。结果表明,2003年到2020年维都林场森林资源在数量上有较大的增加,森林质量有所上升,从及格等级上升到中等等级,当前制约森林质量提升关键评价指标是单位面积蓄积量严重偏低、平均径级偏小。针对存在问题提出了精准提升森林质量的意见建议。In order to known the changes of forest resource quantity and quality in Guangxi state-owned Weidu Forest Farm, to promote high-quality development of forest resources in the forest farm, using the data of forest resource investigation of the forest farm from 2003 to 2020,woodland,forest area, forest stock volume, forest covering rate, forest growth, per unit area stock volume, forest consumption were statistically analyzed, and the forest resource quality was evaluated according to its forest origin, structure, productivity, health and value. The results are as follows: the forest resource quantity was increased and forest quality was promoted from 2003 to 2020. The rank of the forest resource quality valuation was increased from pass to medium. The key indicators restricting forest quality were that per unit area stock volume and DBH (diameter-breast-height) were very small. Some suggestions for accurate promoting the forest quality in Weidu Forest Farm were proposed.展开更多
文摘工程结构在制造工艺过程中或使用期间会产生裂纹,对结构断裂路径的预测和研究是防治工程安全问题发生的重要手段。在考虑裂纹尖端应力场常数项T应力的基础上对传统的最大周向应力准则(Maximum tangential stress criterion,MTS)和最小应变能密度因子准则(Minimum strain energy density criterion,SED)进行修正,采用Python语言对ABAQUS的前、后处理和有限元计算模块进行二次开发,通过计算最优解的粒子群算法(Particle swarm optimization,PSO)将修正后的准则编入裂纹自动扩展程序脚本中。利用上述二次开发程序对初始纯Ⅰ型裂纹的扩展路径进行模拟,结果表明:采用ABAQUS脚本程序模拟结果与相关文献实验结果吻合,表明了程序的有效性,进而实现考虑T应力的多种断裂准则对裂纹扩展路径的预测;当T应力值处于一定范围内时,修正的MTS准则无法预测裂纹发生的偏转现象,扩展路径呈直线,此时可采用修正的SED准则进行预测。
文摘为全面掌握林场森林资源数量与质量变化情况,促进林场森林资源高质量发展,采用2003-2020年广西国有维都林场森林资源规划设计调查报告数据,对林业用地、森林面积、森林蓄积、森林覆盖率、森林生长量、森林消耗量等49项指标分析森林资源数量动态变化;并采用层次分析法在森林起源、森林结构、森林产能、森林健康、森林价值等方面综合评价森林质量。结果表明,2003年到2020年维都林场森林资源在数量上有较大的增加,森林质量有所上升,从及格等级上升到中等等级,当前制约森林质量提升关键评价指标是单位面积蓄积量严重偏低、平均径级偏小。针对存在问题提出了精准提升森林质量的意见建议。In order to known the changes of forest resource quantity and quality in Guangxi state-owned Weidu Forest Farm, to promote high-quality development of forest resources in the forest farm, using the data of forest resource investigation of the forest farm from 2003 to 2020,woodland,forest area, forest stock volume, forest covering rate, forest growth, per unit area stock volume, forest consumption were statistically analyzed, and the forest resource quality was evaluated according to its forest origin, structure, productivity, health and value. The results are as follows: the forest resource quantity was increased and forest quality was promoted from 2003 to 2020. The rank of the forest resource quality valuation was increased from pass to medium. The key indicators restricting forest quality were that per unit area stock volume and DBH (diameter-breast-height) were very small. Some suggestions for accurate promoting the forest quality in Weidu Forest Farm were proposed.
