浮体稳定平衡的条件

浮体所受浮力的作用点一般不与其重力的作用点重合.那么,浮体在什么条件下平衡,是否在其重心低于浮心的情况下稳定平衡,这个问题容易产生误解.本文指出,决定浮体平衡与否的是重心与定倾中心的相对位置,而不是重心与浮心的相对位置,在重心低于或等于定倾中心时,浮体就处于稳定平衡.     

论国共合作的恒定条件 --以两次国共合作为例

以两次国共合作为例,阐明党派合作需要具备一定的恒定条件第一,两党为实现自己的总目标都面临着一个消除民族危机,实现民族复兴的共同的任务;第二,这个共同的任务单靠任何一党的力量都是难于单独完成的.第一次国共合作国共都难于单独完成的共同任务是反帝反封建,第二次国共合作国共都难于单独完成的共同任务是驱逐日本帝国主义出中国.历史事实证明,在这一恒定条件下完成的国共合作,对国共两党自身的发展壮大,对中国民族走向复兴和强盛,都取得了丰硕的成果.     

金融成长有赖于制度稳定

各种基于市场的金融活动必须依靠一定的法律规则,必须有一个健全但又不失灵活的法律制度基础,也需要一个独立有效的司法体系来支撑和执行各种法律制度。一旦失去了规则的保障和制度环境的依托,金融产品就失去了立身之本。     

关于微分方程△H＋2H（H~2－K）＝0

通过分析椭圆型微分方程△Ｈ＋２Ｈ（Ｈ~２－Ｋ）＝０得到关于闭Ｗ－曲面和卵形面的几个结论。这些结论具有清晰的几何特征，而且属于整体微分几何性质。     

韩国汉字音声母系统的几个特征

韩国从公元前开始借用汉字,虽然韩国语和汉语类型不同,但韩汉音和汉语声韵有密切的联系,这是因为韩国汉字音源于古代中国汉语音。同时,韩国汉字音为韩国语固有语音体系所制约,经过了与汉语不同的发展道路。它形成自己的体系之后,稳固地维护自己的读音规范。到了现代,韩国汉字音和中国普通话语音之间,存在着显著差异。了解韩国汉字音声母系统的特征,可以更好地研究汉语语音史以及中韩语言文学关系史。     

ON CHARACTERIZATIONS THROUGH MIXED SUMS

Let X, X‘ and X“ be independent and have the same law, and let U be uniform on [0,1] and independent of X’ and XI”. A problem which has received considerable attention is to identify the laws of X for which X =c U(X‘+X“), the equality being in law. If X is positive it has an exponential law, and mixture solutions exist without the sign restriction. The problem has been extended to allow more summands on either side and to let U have a special beta law. In the positive case X then has a gamma law. This problem is tackled in full generality by considering an integral equation for the characteristic function of X. Uniqueness results and necessary conditions are given. The general case is reduced to that where X is positive, and the solution of the corresponding integral equation is constructed under the necessary conditions. This is shown to characterize all possible laws of X when there is a single summand on the left and U has an arbitrary law on [0,1]. Examples are given and known particular results are sharpened.     

Policy Stable States in the Graph Model for Conflict Resolution

A new approach to policy analysis is formulated within the framework of the graph model for conflict resolution. A policy is defined as a plan of action for a decision maker (DM) that specifies the DM’s intended action starting at every possible state in a graph model of a conflict. Given a profile of policies, a Policy Stable State (PSS) is a state that no DM moves away from (according to its policy), and such that no DM would prefer to change its policy given the policies of the other DMs. The profile of policies associated to a PSS is called a Policy Equilibrium. Properties of PSSs are developed, and a refinement is suggested that restricts DMs to policies that are credible in that they are in the DM’s immediate interest. Relationships with existing stability definitions in the graph model for conflict resolution are then explored.     

The Evolution of Cooperative Strategies for Asymmetric Social Interactions

How can cooperation be achieved between self-interested individuals in commonly-occurring asymmetric interactions where agents have different positions? Should agents use the same strategies that are appropriate for symmetric social situations? We explore these questions through the asymmetric interaction captured in the indefinitely repeated investment game (IG). In every period of this game, the first player decides how much of an endowment he wants to invest, then this amount is tripled and passed to the second player, who finally decides how much of the tripled investment she wants to return to the first player. The results of three evolutionary studies demonstrate that the best-performing strategies for this asymmetric game differ from those for a similar but symmetric game, the indefinitely repeated Prisoner’s dilemma game. The strategies that enable cooperation for the asymmetric IG react more sensitively to exploitation, meaning that cooperation can more easily break down. Furthermore, once cooperation has stopped, it is much more difficult to reestablish than in symmetric situations. Based on these results, the presence of asymmetry in an interaction appears to be an important factor affecting adaptive behavior in these common social situations.     

Measuring Tail Thickness to Estimate the Stable Index α: A Critique

A generalized Pareto or simple Pareto tail-index estimate above 2 has frequently been cited as evidence against infinite-variance stable distributions. It is demonstrated that this inference is invalid; tail index estimates greater than 2 are to be expected for stable distributions with α as low as 1.65. The nonregular distribution of the likelihood ratio statistic for a null of normality and an alternative of symmetric stability is tabulated by Monte Carlo methods and appropriately adjusted for sampling error in repeated tests. Real stock returns yield a stable α of 1.845 and reject iid normality at the .996 level.     

Risk Finance for Catastrophe Losses with Pareto‐Calibrated Lévy‐Stable Severities

For catastrophe losses, the conventional risk finance paradigm of enterprise risk management identifies transfer, as opposed to pooling or avoidance, as the preferred solution. However, this analysis does not necessarily account for differences between light‐ and heavy‐tailed characteristics of loss portfolios. Of particular concern are the decreasing benefits of diversification (through pooling) as the tails of severity distributions become heavier. In the present article, we study a loss portfolio characterized by nonstochastic frequency and a class of Lévy‐stable severity distributions calibrated to match the parameters of the Pareto II distribution. We then propose a conservative risk finance paradigm that can be used to prepare the firm for worst‐case scenarios with regard to both (1) the firm's intrinsic sensitivity to risk and (2) the heaviness of the severity's tail.