体制变迁下的兰州城市总体规划实施效果分析

城市总体规划两项最重要的功能——预测城市人口、用地规模;对城市各项建设用地在空间上作出具体安排,为了检测这两项功能在不同时期发挥作用的效果,笔者运用GIS分析方法,结合城市现状人口数据分析,结果发现:传统计划经济时期城市规划人口预测畸形地符合规划期末现状人口,而改革开放以来人口预测与现实偏差巨大;在用地布局方面,不管是计划经济时期,还是改革开放以来,不同类型的城市建设用地在组团城市中的各个组团实施效果也差别明显,但实施效果均不如预期。最后通过回顾新中国成立以来各种与城市发展相关的制度演变发现:影响城市总体规划实施的根本原因是规划期内各种剧烈的社会动荡和深刻的政治和经济体制的转变。     

Glutamine Induced High-Quality Perovskite Film to Improve the Efficiency of NIR Perovskite Light-Emitting Diodes

Formamidine lead iodide (FAPbI₃) is an important material for realizing high-performance near-infrared light-emitting diodes (NIR-LEDs). However, due to the uncontrollable growth of solution-processed films which usually causes low coverage, and poor surface morphology, the development of FAPbI₃-based NIR-LEDs is hindered, restraining its potential industrial applications. In this work, by employing glutamine (Gln) in perovskite precursor, the quality of FAPbI₃ film is improved significantly. Due to the ameliorated solution process by the organic additive, the film coverage over the substrate is substantially enhanced. Meanwhile, the trap state of grain is largely reduced. Consequently, NIR perovskite LEDs are demonstrated with a maximum external quantum efficiency (EQE) of 15% with the emission peak at 795 nm, which is four times higher than the device with pristine perovskite film.