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生态恢复理论下的人居景观规划设计及生态建设研究 被引量:3
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作者 楚芳芳 《环境科学与管理》 CAS 2020年第12期142-147,共6页
为改善居住生态环境,提出生态恢复理论下人居景观规划设计及生态建设。利用热力学定律获取熵值,作为生态稳定度量,构建居住区生态系;根据三维景观图像计算植被覆盖率、建筑密度等指数,确保自然景观与人工景观相宜;获取平均斑块面积、景... 为改善居住生态环境,提出生态恢复理论下人居景观规划设计及生态建设。利用热力学定律获取熵值,作为生态稳定度量,构建居住区生态系;根据三维景观图像计算植被覆盖率、建筑密度等指数,确保自然景观与人工景观相宜;获取平均斑块面积、景观形状等规划设计指标,通过生态干扰频率与强度确定生物数量与种类;采用空间格局梯度优化建立潜力预测模型,完成对人居景观植被、水环境、园路的设计。实验结果表明,该方法可以提高人居景观生物多样性,满足生态恢复要求。 展开更多
关键词 生态恢复 人居景观 规划设计 空间梯度优化 生物多样性
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A Barzilai-Borwein conjugate gradient method 被引量:7
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作者 DAI YuHong KOU CaiXia 《Science China Mathematics》 SCIE CSCD 2016年第8期1511-1524,共14页
The linear conjugate gradient method is an optimal method for convex quadratic minimization due to the Krylov subspace minimization property. The proposition of limited-memory BFGS method and Barzilai-Borwein gradient... The linear conjugate gradient method is an optimal method for convex quadratic minimization due to the Krylov subspace minimization property. The proposition of limited-memory BFGS method and Barzilai-Borwein gradient method, however, heavily restricted the use of conjugate gradient method for largescale nonlinear optimization. This is, to the great extent, due to the requirement of a relatively exact line search at each iteration and the loss of conjugacy property of the search directions in various occasions. On the contrary, the limited-memory BFGS method and the Barzilai-Bowein gradient method share the so-called asymptotical one stepsize per line-search property, namely, the trial stepsize in the method will asymptotically be accepted by the line search when the iteration is close to the solution. This paper will focus on the analysis of the subspace minimization conjugate gradient method by Yuan and Stoer(1995). Specifically, if choosing the parameter in the method by combining the Barzilai-Borwein idea, we will be able to provide some efficient Barzilai-Borwein conjugate gradient(BBCG) methods. The initial numerical experiments show that one of the variants, BBCG3, is specially efficient among many others without line searches. This variant of the BBCG method might enjoy the asymptotical one stepsize per line-search property and become a strong candidate for large-scale nonlinear optimization. 展开更多
关键词 conjugate gradient method subspace minimization Barzilai-Bowein gradient method line search descent property global convergence
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