利用数据缓存技术提升系统性能的探讨

Web在线系统在服务器物理性能无法提升的前提下,如何采用合适的系统架构和优化算法是广大系统开发人员努力的方向。本文探讨了如何利用J2EE中的MMF技术,利用设计的价制度优化算法提升系统性能,并利用LoadRunner软件进行了效果验证。     

城市肌理的传承与更新——河西古镇开发中街道空间的延续

城市肌理是随着人类社会历史的发展而逐步演化的产物,是一个城市人文记忆和历史信息的载体,如何在城市肌理中延续城市的历史文脉,解读城市的人文记忆,构筑城市的美好未来,必然成为城市发展的重中之重。在河西古镇开发中如何保护原有城市肌理,延续城市的历史文脉,做到保护城市的历史信息和风貌特征的同时,又能改善人居环境,使新的城市肌理能够"有机切入"原有肌理,成为一个必须重视的现实问题。     

Dynamic contracting under imperfect public information and asymmetric beliefs

We develop a dynamic principal–agent model to show how imperfect public information and asymmetric beliefs about payoff-relevant parameters, agency conflicts, and the agent's implicit incentives to influence the principal's posterior beliefs through his unobservable actions interact to affect optimal dynamic contracts. We make a methodological contribution to the literature by solving the continuous-time contracting problem using a discrete-time approximation approach. We obtain a simple characterization of optimal renegotiation-proof contracts in terms of the solution to a nonlinear ordinary differential equation (ODE). We then exploit the properties of the ODE to derive a number of novel implications for the dynamics of long-term contracts that alter the intuition gleaned from the previous literature. Optimism has a first-order impact on incentives, investment and output that could reconcile the “private equity” puzzle. Consistent with empirical evidence, the interaction between asymmetric beliefs, risk-sharing and adverse selection costs could cause the time-paths of the agent's incentive intensities to be increasing or decreasing. Our results also suggest that the incorporation of imperfect public information and asymmetric beliefs could potentially reconcile empirical evidence of an ambiguous relation between risk and incentives, and a non-monotonic relation between firm value and incentives. Permanent and transitory components of risk have differing effects on incentives, which suggest that empirical investigations of the link between risk and incentives should appropriately account for different components of risk.     

Learning from the alien: knowledge relationships with temporary workers in network contexts

This paper contributes to our understanding of the role of temporary workers in learning for innovation in network contexts. The strategy literature advocates that the knowledge and talent of workers is vital to competitive success yet at the same time temporary workers are becoming more prevalent, making relationships with workers more ephemeral. These shifting competitive and employment contexts make insights into learning from, and with, contractual nomads paramount. The setting is the UK television industry, where such workers are dominant. Internationally, creative industries are a prime site of networks where temporary workers are brought together for specific projects. In the television industry, a range of knowledge attachment employee relationships have been developed by firms to ‘contain’ and sustain worker contributions in terms of knowledge and talent. These relationships are identified as freelance, regular contract, golden handcuffs and invest in knowledge firm. This paper highlights the learning implications both positive and negative arising from these different ways of relating to temporary workers thereby extending our understanding of employee relationships built on mutuality.     

Approachability with bounded memory

We study Blackwell's approachability in repeated games with vector payoffs when the approaching player is restricted to use strategies with bounded memory: either strategies with bounded recall, or strategies that can be implemented by finite automata. Our main finding is that the following three statements are equivalent for closed sets. (i) The set is approachable with bounded recall strategies. (ii) The set is approachable with strategies that can be implemented with finite automata. (iii) The set contains a convex approachable set. Using our results we show that (i) there are almost-regret-free strategies with bounded memory, (ii) there is a strategy with bounded memory to choose the best among several experts, and (iii) Hart and Mas-Colell's adaptive learning procedure can be achieved using strategies with bounded memory.     

Does trade foster contract enforcement?

Contract enforcement is probabilistic, but the probability depends on rules and processes. A stimulus to trade may induce traders to alter rules or processes to improve enforcement. In the model of this paper, such a positive knock-on effect occurs when the elasticity of supply of traders is sufficiently high. Negative knock-on is possible when the elasticity is low. Enforcement strategies in competing markets are complements (substitutes) if the supply of traders is sufficiently elastic (inelastic). The model provides a useful structure of endogenous enforcement that gives promise of explaining patterns of institutional development. Presented to the GEP Conference on ‘New Directions in International Trade Theory’, 8 and 9 June, 2007. An earlier version of this paper under another title was presented to the American Economic Association meetings, January 2004.     

Commitment and observability in a contracting environment

This paper examines leader-follower games where a leader must purchase an essential input from a price-setting supplier in order to take an action. We show that equilibrium outcomes when the followers perfectly observe the leaders' actions cannot be approximated by mixed equilibrium outcomes of the game where followers imperfectly observe the leaders' actions, i.e. they are not accessible. Accessibility fails since in a pure strategy equilibrium, a supplier makes positive profits; however in an equilibrium where a leader randomizes, supplier profits must be zero. Our result follows from a generalized indifference principle that mixed strategies must satisfy in economic environments. While supplier profits cannot be approximated, player action profiles are accessible. Our results also apply to games with costly observation.     

Strategic Investment Decisions under Uncertainty,Tacit Collusion and Product Differentiation

This paper examines the effects of uncertainty, tacit collusion and product differentiation on strategic investment policy. The model demonstrates the equilibrium under competitive investments and under cooperative investments. In competitive investments, two firms compete by investing to preempt each other, and ultimately one firm invests earlier than its rival. In cooperative investments, two firms invest simultaneously and collude on their outputs. Cooperative investments are likely to be sustainable only under conditions of high volatility of future demand, low probability of market extinction and high degree of product differentiation, while competitive investments are sustainable for any set of these parametric values.     

从美国房价走势透视中国房地产市场走向

内容文章从量化分析的角度出发,研究了全美50个州和哥伦比亚特区房价指数序列的记忆性特征,发现各州房价指数序列均具有一定程度的长记忆性.同时,我们对50个州房价指数记忆参数的估计值进行了聚类分析,由此发现各州房价指数的记忆性呈现出一定的地区聚集性特征,而且还与地区的人口密度存在一定关系,从而为宏观政策制定者在决定房价调控措施的时候提供了有益的新思维,可使楼市更加健康稳定地发展.此外,文章的研究结果对于解决我国房地产市场目前存在的巨大泡沫问题提供了一个全新的视角     

企业为何要即兴运作:对中国企业战略决策风格的一个检验

文章以中国企业为研究对象,全面探究了其战略决策中的即兴运作行为,认为即兴运作作为一种可供选择的战略行动模式而值得关注.文章的研究结论表明:即兴运作在中国企业是一个较为普遍的现象.企业对战略行动的选择是由多种因素综合驱动的,当企业的组织记忆水平越高、企业家导向越明显以及所面对的竞争环境不确定性程度越高时,企业就越可能采取即兴运作的战略行动方式;即兴运作虽然会对战略行动绩效产生负面影响,但组织柔性会显著降低其负面作用.