造园组创办始末

1951—1953年创办的造园组对中国风景园林学科 和教育影响深远。基于档案文件，以时间为序，描述造园组成 立的背景、沿革和办学情况，讨论造园组停办的主要原因。研 究表明：造园组隶属于北京农业大学园艺系，清华大学营建学 系合办，北京市人民政府建设局协办；汪菊渊、吴良镛、陈有 民以及梁思成等先生在造园组成立和建设之中发挥了重要的作 用；造园组是一个相对独立的教学和行政组织；造园组的成立 依赖于一系列的背景条件。     

The maximal covering location problem with accessibility indicators and mobile units

We study the Maximal Covering Location Problem with Accessibility Indicators and Mobile Units that maximizes the facilities coverage, the accessibility of the zones to the open facilities, and the spatial disaggregation. The main characteristic of our problem is that mobile units can be deployed from open facilities to extend the coverage, accessibility, and opportunities for the inhabitants of the different demand zones. We formulate the Maximal Covering Location Problem with Accessibility Indicators and Mobile Units as a mixed-integer linear programming model. To solve larger instances, we propose a matheuristic (combination of exact and heuristic methods) composed of an Estimation of Distribution Algorithm and a parameterized Maximal Covering Location Problem with Accessibility Indicators and Mobile Units integer model. To test our methodology, we consider the Maximal Covering Location Problem with Accessibility Indicators and Mobile Units model to cover the low-income zones with Severe Acute Respiratory Syndrome Coronavirus 2 patients. Using official databases, we made a set of instances where we considered the poverty index, number of population, locations of hospitals, and Severe Acute Respiratory Syndrome Coronavirus 2 patients. The experimental results show the efficiency of our methodologies. Compared to the case without mobile units, we drastically improve the coverage and accessibility for the inhabitants of the demand zones.