美国深空网的同波束干涉测量技术

讨论了美国NASA深空网(DSN)对深空飞船所采用的同波束干涉(SBI)技术概念和测量原理，并介绍了这一技术的应用和发展情况。     

正度拟齐次Toeplitz算子的乘积

在Bergman空间上讨论了以拟齐次函数为符号的Toeplitz算子的乘积问题.使用Mellin变换作为工具,得出了当拟齐次函数的度都为正度时两个Toeplitz算子乘积仍是Toeplitz算子的充分必要条件,完善了以往文献中的有关结果.     

Economics and underdetermination: a case study of urban land and housing economics

Underdetermination, associated with the Duhem–Quine thesis,is a familiar if under-researched theme in economics. In thelight of this, we examine the development of urban land andhousing economics. Through its Cartesian dualistic delineationof theory and data, the contemporary mainstream approach appearsunable to circumvent the problem of underdetermination. In effect,it employs the strong version of Duhem–Quine in its retentionof the assumption of a single, unitary competitive market (andassociated access–space trade-off). Conversely, we highlightthe affinity of Ely's (and the later Columbia School's) approachto pragmatists Dewey and Peirce, which provides a more fruitfulbasis for explanation.     

Who's in charge of the central city? The conflict between efficiency and equity in the design of a metropolitan area

A circular metropolitan area consists of a central city surrounded by a suburb. Households sort over the two jurisdictions based on public service levels and their costs of commuting to the metropolitan center. Using numerical simulations, we show that (1) there typically exist two equilibria: one in which the poor form the voting majority in the central city and the other in which the rich form the majority in the central city; (2) there is an efficiency vs. equity trade-off as to which equilibrium is preferred; and (3) if the central city contains only poor households, equity favors expanding the central city to include rich households. The third result arises not because of a fiscal subsidy from rich to poor households induced by a property tax but rather because of a change in house price capitalization.     

The topography of metropolitan employment: Identifying centers of employment in a polycentric urban area

While it is well recognized that US metropolitan areas are polycentric, there is little consensus as to the appropriate method for identifying concentrations of employment within them. Existing methods suffer from strong assumptions about parametric form, misspecification, or reliance on local knowledge to calibrate model parameters. This paper introduces a new nonparametric method for identifying subcenters. Results indicate that this, more flexible, nonparametric approach yields greater accuracy with regard to both urban and suburban centers compared with other approaches. This approach should provide better data for the numerous topics that depend on the spatial accounting of employment within metropolitan areas.     

我国城乡耐用消费品市场用户构成差异的研究——一个创新扩散的视角

创新扩散理论按照用户采用新产品的时间先后顺序将市场细分为创新者、早期采用者、早期大多数、晚期大多数和落后者五种类型。本文在扩散经典理论和中国市场特征的基础上,提出城镇市场和农村市场耐用消费品用户构成差异的假设。研究结果证实了全部假设:城镇的创新者比例显著高于农村,农村的早期采用者比例显著超过城镇,而各类型采用者的采用持续时间农村全面长于城镇。这些结论为更加深入地了解二元经济结构下中国市场的特征提供了有益启示。     

城市空间发展哲学思辩

通过对十多个城市空间发展的个案分析 ,作者指出 ,在城市空间拓展过程中 ,通过规划调控、行政区划调整等手段 ,可以使城市劣势空间变优势空间 ,使分割空间变整体空间 ,平淡空间变特色空间 ,变限制空间为超越限制空间     

中国城市住宅市场的结构差异性分析

市场价商品房、经济适用住房和廉租房构成了目前中国城市住宅市场的供应体系.依据中国30个主要城市的房地产开发统计数据,选择吸纳率作为评价住宅市场供需均衡状态的指标,利用固定影响变截距模型,重点研究了商品房和经济适用住房供给结构的城市差异性.研究发现,在城市住宅市场中,经济适用住房市场和商品房市场具有很强的相关性.作为具有政府资助性质的经济适用住房建设,存在典型的地域性特征,其政策的设定和实施会对整个住宅市场产生影响,地方政府应在利用比较全面的住宅市场指标体系进行综合分析基础上,制定适合本地的经济适用住房政策.     

Study on the planning principles of urban forest

The urban forest is the main body for the urban forestry management. There are not unified rules and standards for the planning of the urban forest yet in China. This paper discusses the planning principles of the urban forest： the priority of the ecological function, the adaptation to local condilions, the optimization in the whole system, the mutual dependence of forest and city, the culturecontinuance and recreation satisfaction, sustainable development and operability, etc. This paper takes Changsha as an example to elaborate the planning principles of the urban forest. Firstly, Changsba urban forest ecosphere is composed of the eco-garden, the round-the-city forest belt, the ecological isolation belt, the green channel, the landscape of the rivers and streams, the forest park, the biodiversity reserve and the eco-forest in suburb area. It aims to make every kind of ecological essential factors organically merge into the complex city ecosystem to build an eco-city, to strengthen the connection of wide-open space with various habitats spots, to promote resident＇s accessibility, to perfect landscape ecology, and to make full use of the ecological function of urban forest. When we construct the urban forest, we must optimize the comprehensive benefit and make the urban forest structure and the layout in the best condition in order to buiM the harmonious green city for both man and nature to realize the whole optimization of the city system by the complex functions of the urban forest in ecology, environmental protection, landscape, recreation, etc.     

北京市农村集体建设用地规划管理研究

通过分析北京农村集体建设用地规划管理现状,明确农村集体建设用地规划管理工作中存在的问题以及根源,提出符合北京实际的农村集体建设用地规划管理体系建议,为进行社会主义新农村建设构建良好的制度框架,保障新一轮北京城市总体规划在部区的有效实施.