一类带有Dirichlet边界值条件的椭圆型方程正解的存在性

利用欧拉变分原理,证明了一类带有Dirichlet边界值条件的椭圆型方程正解的存在性。     

An overview of cricket ball swing

The aerodynamic properties of a cricket ball have intrigued cricket players and spectators for years, arguably since the advent of the game itself. The main interest is in the fact that the ball can follow a curved flight path that may not always be under the control of the bowler. The basic aerodynamic principles responsible for the nonlinear flight or ‘swing’ of a cricket ball were identified decades ago and many papers have been published on the subject. Over the last 25 years or so, several empirical investigations have also been conducted on cricket ball swing, which revealed the amount of attainable swing and identified the parameters that affect it. Those findings are reviewed here with emphasis on phenomena such as late swing and the effects of humidity on swing. The relatively new concept of ‘reverse swing’, how it can be achieved in practice, and the role in it of ‘ball tampering’, are also discussed in detail. In particular, the ability of some bowlers to effectively swing an old ball in the conventional, reverse and the newly termed ‘contrast’ swing mode is addressed. A discussion of the ‘white” cricket ball used in the 1999 and 2003 World Cup tournaments, which supposedly possesses different swing properties compared to a conventional red ball, is also included. This is a current overview of cricket ball swing rather than a detailed review of all research work performed on the topic. The emphasis is on presenting scientific explanations for the various aerodynamic phenomena that affect cricket ball swing on a cricket ground.     

产业边界决策与企业战略性风险分析

从交易经济性、资源优势和不确定性角度分析了企业纵向边界决策风险,从业务间关联、共享和协同的角度分析了企业横向边界决策风险,探讨了在不同决策取向下企业在边界内外经营平衡的比较及其形成的战略性风险。     

产学合作网络中企业关系势能与自主创新绩效——基于地理边界拓展的调节作用

本文采用中国有机化学行业的产学合作专利数据,进行专利地图分析,并以参与产学合作的企业的自主创新绩效为因变量,构建非平衡面板数据下的负二项回归模型,研究产学合作网络中,企业的关系势能对企业自主创新绩效的影响,并考察合作网络的地理边界拓展对二者关系的调节作用。分析结果发现我国有机化学行业的产学合作近几年增速放缓,且已呈现出地理边界拓展的形态,回归结果支持了部分假设:企业的直接关系规模和间接关系强度与企业自主创新绩效正相关,合作网络的地理边界拓展正向调节间接关系规模、间接关系强度与企业自主创新绩效的关系。     

企业联盟、企业集团与“共谋垄断”的边界——兼论培育中国企业国际竞争力的新思路

企业联盟作为企业间合作博弈战略,是“市场———准市场组织———企业”三分析框架的产物,与外部一体化的市场安排相比,企业联盟是一种“组织化市场”;与内部一体化的层级制度安排相比,企业联盟是一种“市场化组织”。企业联盟与企业集团连接纽带、法律地位、经营目标等方面形貌相似,极易对之发生认识上的偏差,但二者具有实质的差别。中国企业集团化面临着产权模糊、行政干预等现实障碍。中国企业应转变战略视角,以联盟而非以集团化作为培育具有国际竞争力企业的首选。但作为企业间的契约结合与股权结合形式,联盟应时刻警惕其与“共谋垄断”的界限。     

企业知识传导与知识边界研究

本文分析了企业知识边界的存在性，并以知识传导成本与收益模型分析企业知识边界大小及其动态性。同时，研究并探讨企业知识边界与知识传导的关系，知识边界的模糊化、动态性及其与企业的治理结构的关系。     

Awkwardness of becoming a boundary object: Mangle and materialities of reports,documentation data,and the archaeological work

Information about an archaeological investigation is documented in an archaeological report, which makes it the boundary object par excellence for archaeological information work across stakeholder communities such as field archaeologists, heritage managers, and land developers. The quality of reports has been a subject of debate, and recently it has been argued that more emphasis should be placed on making primary research data at least similarly available. This study explores the changing materialities and reciprocal formation of documents and their users with the advent of digitization, and how documents form and lose their status as boundary objects in these processes. The study posits that in order to be functional, a boundary object needs to provide a disclosure that makes it accessible to cognate communities. Further, it shows how assumptions about the functioning of the human and nonhuman (material artifacts) influence the ways in which archaeologists conceptualize the preservation and archiving of archaeological information and the role and potential of different types of digital and paper-based documents. This article is based on an interview study of Swedish archaeology professionals (N = 16) with theoretical underpinnings in the notions of boundary objects, mangle of practice, and disclosure.     

兰州市城区稳定边界层变化规律的初步研究

兰州市城区空气污染严重与其特殊的大气边界层密切相关。利用兰州市城区现有大气边界层探测资料 ,采用多种稳定度参数计算方法 ,统计分析了该市大气层结稳定度的时空分布规律及其与天气形势的关系 ,发现兰州市城区冬季大气稳定边界层日间存在发生或发展的特有现象 ,并探寻了其形成机制 ,从而为兰州市开展空气污染预报提供可靠的理论依据     

Designing for communication at work: A case for technology-enhanced boundary objects

In this article we conceptualise the challenges of communication between a mortgage company and its customers in terms of crossing boundaries between communities. Through an ethnographic study we first address the question: what are the challenges of communication between sales agents and customers of a mortgage company around mathematical artefacts? Insight into these challenges formed the basis for an intervention in which we designed technology-enhanced boundary objects (TEBOs) that were reconfigurations of problematic symbolic artefacts. Secondly, we ask what the sales agents learned from the intervention. The data suggest that the intervention with the TEBOs helped employees to develop a better understanding of the mathematics behind the mortgages they sold, and to improve communication with their customers.