企业规模对专利产出影响的实证分析——基于1998—2010年上市公司经验证据

使用1998—2010年中国A股上市公司的年度数据,研究了企业规模对专利产出和专利密度的影响。结果表明:发明专利和实用新型专利与企业规模之间存在U型关系,外观设计专利与公司规模呈倒U型关系;三类专利的专利密度都与企业规模之间存在U型关系;企业的知识存量、成立时间、财务杠杆、所有制类型等企业内部因素以及市场集中度、企业所处区域等外部环境因素都对企业的专利产出有显著影响。据此提出企业创新发展路径假说。     

Knowledge distance and R&D collaboration in Cournot oligopoly

A Cournot collaboration game is complemented with the hypothesis that the cost of R&D collaboration depends on firm’s directed knowledge distance with respect to potential R&D partners. The further hypothesis that directed distance may be non‐uniform and pair‐wise asymmetric reconciles theoretical predictions with qualitative evidence about concentration and multiplicity of components in industrial R&D networks. The welfare properties of sparse stable networks are also affected.     

Impact of distance on the arrivals,behaviours and attitudes of international tourists in Hong Kong: A longitudinal approach

This study revisits the impact of distance on international tourist behaviours in Hong Kong. This work divides and cross-validates the concept of distance into physical and cultural distance. This work also proposes an alternative cultural distance measure by introducing optimal weight amongst Hofstede's dimensions and then compares the proposed measure with the traditional Kogut and Singh's and Kandogan's measures. By using data from the Visitor Profile Report of the Hong Kong Tourism Board and the World Trade Organisation from 2002 to 2017, along with latent growth curve modelling, multivariate regression and panel data analysis, findings confirmed the significant role of physical and cultural distance. In addition, quadratic relationships are detected using cross-validation methods. The effect of physical distance on tourist demands clearly dominates that of cultural distance in the overall market. The problem of spurious correlation and the results of three cultural distance measures are also discussed.     

中国区域城市体系演化实证研究

针对我国区域城市体系发展现状,对该体系的演化过程进行了实证分析,考察了我国城市体系的区域分布特征、区域城市体系的分布密度以及规模结构.研究结论显示,东部省份城市的数量和空间分布密度要明显高于中西部地区,说明东部地区城市体系的发育程度处于领先地位;同时,分析结果也表明,各地区城市体系的规模结构演化趋势较为一致,都经历了一个先分散、后集中的过程.     

国外城市蔓延研究进展

在对国外关于"城市蔓延"概念的界定进行综述的基础上,对"城市蔓延"的成本效益、肌理、定量化方法及其对环境的影响进行分析,最后得出对我国城市化的有益启示。     

Urban density and pupil attainment

We explore the association between urban density and pupil attainment using three cohorts of pupils in schooling in England. Although—as widely recognised—attainment in dense urban places is low on average, this is not because urban environments disadvantage pupils, but because the most disadvantaged pupils with low average attainments attend the most urbanised schools. To control for this, we exploit changes in urban density faced by pupils during compulsory transition from Primary to Secondary school, and measure educational progress at the end of the Secondary phase, relative to attainment at the end of Primary schooling. Our results suggest that there are small but significant benefits from education in schools in more densely urbanised settings. We detect this density advantage even amongst pupils moving relatively short distances between Primary and Secondary schools within urban areas, so we cannot attribute it to broad urbanisation effects experienced by pupils making rural–urban school moves. A more likely explanation lies in greater school choice and competition between closely co-located educational providers.     

Some antecedent factors that shape actors’ adoption of enterprise systems

This paper proposes a conceptual model based on technology-organization-environment (T-O-E) and institutional frameworks and examines how the traditional and isomorphic factors explain adoption of enterprise systems (ES) by service small and medium enterprise (SMEs) in Nigeria. The model extends the T-O-E framework by integrating environmental typology with institutional changes in order to recognize homologous behavior in the social systems. Logistic regression and Wald’s statistics were used to analyze the data from field survey questionnaire administered to a purposive and snow-ball sample of 262 executives. The results show that adoption of ES is significantly influenced by organizational, technological and isomorphic factors though normative and mimetic isomorphism had negative coefficients; a unit increase in the complexity of the two attracts less analogous modeling and mimicry or vice versa. The technical, economic and legitimated elements are critical adoption determinants; thus, managers make informed decisions that improve competitive advantage when they understand the institutional homogeneity that drives less efficiency in the social structure.     

Optimal portfolio allocation under the probabilistic VaR constraint and incentives for financial innovation

We characterize the investor’s optimal portfolio allocation subject to a budget constraint and a probabilistic VaR constraint in complete markets environments with a finite number of states. The set of feasible portfolios might no longer be connected or convex, while the number of local optima increases exponentially with the number of states, implying computational complexity. The optimal constrained portfolio allocation may therefore not be monotonic in the state–price density. We propose a type of financial innovation, which splits states of nature, that is shown to weakly enhance welfare, restore monotonicity of the optimal portfolio allocation in the state-price density, and reduce computational complexity. We are grateful to Ken Kavajecz and seminar participants at Harvard Business School, London School of Economics, Maastrict University, ZEI Bonn, and Danske Bank Symposium on Asset allocation and Value-at-Risk: Where Theory Meets Practice for comments on an earlier version of this paper. We also benefitted from the suggestions of two anonymous referees. Our papers can be downloaded from www.RiskResearch.org.     

低温低密度水泥复合减轻材料研究

深水固井一直存在低环境温度、低破裂压力梯度、潜在浅层流、材料成本较高等技术难题。针对这些问题开发出了一种适用于低温（10 ℃）深水固井的低密度水泥复合减轻材料体系KBS1053,该水泥体系的密度为1.55 g/cm3,具有低温下凝结速度较快、低温强度发展较好、浆体流动性较好等特点,其早期抗压强度高于同等密度空心玻璃微珠低密度水泥体系,且原材料来源广泛,具有良好的工程性能和经济效益。     

工程物探技术在地下库可研阶段勘察中的应用

根据某大型地下水封石油油库可研阶段勘察实施过程,介绍大型地下水封石油油库可研阶段工程勘察的要求和方法、工程物探种类、高密度电法和地震反射法的原理、方法、实施过程中的应用情况、勘察成果整理分析。阐述了物探与钻探、地质测绘相互验证对建库条件的评价。