The experience of it manufacturing clusters in guangdong indicates that whether local clusters can upgrade its technology or realize sustainable development depends on many factors , such as , the regional element cost and exterior effect of cluster , the technological gap between local enterprise and mne , the nature of foreign enterprise and the technological structure etc 摘要广东东莞it制造业集群的经验表明，本地集群能否借助外资实现技术升级与可持续发展，除了受地方要素成本及集群外部效应的影响之外，还受到本地企业与外资企业的技术差距、外资企业的性质、技术结构等多种因素的影响。
To improve the performance of ashp , an improved ashp system is presented . different from the original system , the new one can control the refrigerant flow rate by the sub - cooling of condenser and adjust the sup - heating of the compressor inlet vapor by the heater in accumulator . the simulation shows the new system not only has better dynamic characteristic of frost and defrost of ashp , but also has higher coefficient of performance 为改善空气源热泵机组的结霜除霜动态性能，提出了一种利用冷凝器过冷度来调节制冷剂流量，在气液分离器里增加电热装置保持压缩机进口过热度的改进型系统，结果表明这种改进型系统不但可以改善系统的运行性能，同时能改善系统运行的经济性，为机组的技术升级和产品更新提供了一个新的途径。
