Designing rewards-based crowdfunding campaigns for strategic (but distracted) contributors

In rewards-based crowdfunding, entrepreneurs solicit donations from a large number of individual contributors. If total donations exceed a prespecified funding target, the entrepreneur distributes nonmonetary rewards to contributors; otherwise, their donations are refunded. We study how to design such campaigns when contributors choose not just whether to contribute, but also when to contribute. We show that strategic contribution behavior—when contributors intentionally delay until campaign success is likely—can arise from the combination of nonrefundable (potentially very small) hassle costs and the risk of campaign failure, and can explain pledging patterns commonly observed in crowdfunding. Furthermore, such delays do not hurt the entrepreneur if contributors are perfectly rational, but they do if contributors are distracted, that is, if they might fail to return to the campaign after an intentional delay. To mitigate this, we find that an entrepreneur can use a simple menu of rewards with a fixed number of units sold at a low price, and an unlimited number sold at a higher price; this segments contributors over time based on the information they observe upon arrival. We show that, despite its simplicity, such a menu performs well compared to a theoretically optimal menu consisting of an infinite number of different rewards and price levels under many conditions.     

RCS特性辅助的CMIMO雷达功率资源分配方法

针对集中式多输入多输出(collocated multiple-input multiple-output, CMIMO)雷达在实际探测过程中,未有效结合目标雷达散射截面(radar cross section, RCS)高动态变化特性导致雷达跟踪精度不高甚至失跟的问题,提出一种基于目标RCS高动态特性的CMIMO雷达功率资源自适应分配方法。考虑到目标RCS特征的角度敏感性,利用目标运动状态的可预测性动态获取实际观测角度,从而完成跟踪帧的极化方式优选;在此基础上构建包含功率与RCS的多目标跟踪误差后验克拉美罗下界,将其作为目标函数进行优化,利用内点惩罚法求解该凸优化问题即可实现RCS高动态情况下的功率优化分配。实验结果表明:该方法可结合目标不同方向RCS动态分集特性实现功率的有效分配,相比于传统RCS模型分配方案,有效解决了分配方案与实际跟踪场景之间的失配问题,从而提升了CMIMO雷达的多目标跟踪性能。     

STUDY ON REALISTIC TECHNOLOGY OF CONDITION MONITORING AND FAULT DIAGNOSTIC SYSTEM FOR SHIPPING POWER DEVICES

ＳＴＵＤＹＯＮＲＥＡＬＩＳＴＩＣＴＥＣＨＮＯＬＯＧＹＯＦＣＯＮＤＩＴＩＯＮＭＯＮＩＴＯＲＩＮＧＡＮＤＦＡＵＬＴＤＩＡＧＮＯＳＴＩＣＳＹＳＴＥＭＦＯＲＳＨＩＰＰＩＮＧＰＯＷＥＲＤＥＶＩＣＥＳＷｅｎＸｉｓｅｎ;ＬｉＹｕｅ;ＴａｎｇＢｉｎｇｙａｎｇ（Ｄｅｐ...     

泛函在射表逼近中的应用

运用泛函理论,对方差最小原则下射表逼近进行分析,给出了在给定基函数形式条件下的统一计算公式,并对最小二乘方法作了改进,消除系数矩阵的原理误差,给出了提高精度的方法。最后,提出了一个选择基函数的有效方法。     

装备贮存可靠性指标的统计描述

对军用装备的贮存可靠性指标进行统计描述,对装备系统常见的有性能参数要求的机械、电子整机,有强度要求的结构件整机和一次性使用产品等三大类型军用装备的贮存可靠性给出定量评定的模型。     

某型反坦克导弹充电器改进研究

简析了某型反坦克导弹武器系统充电器的工作原理及主要缺点,按照简单、高效、可靠的原则对电路提出了改进方案。应用开关电源技术完成了充电主回路的设计,应用线性恒流源技术完成了容检放电回路的设计。实验结果表明,该改进方案切实可行。     

How might Democratisation Affect Military Professionalism in Africa? Reviewing the Literature

The search continues for methods to improve security for development in Sub-Saharan Africa. One of the important actors in this security arena is Sub-Saharan African governments’ armies. Much of their capability to meet security challenge depends on how militarily professional they are. The wave of democratic evolution in Africa since 1990 also affected military professionalism. This article reviews three models for assessing how democratisation might affect military professionalism in Sub-Saharan Africa, with special attention to post-conflict states. This should make it possible to decide which analytical methods are most appropriate to measure military professionalism in the particular circumstances of Sub-Saharan African post-conflict democratisation. Depending upon the particular nation-state in question, this decision on analytical methods may be useful for other Sub-Saharan states as well.     

某型运载火箭1/5动力学缩比模型设计

缩比模型试验是获取大型运载火箭动特性的一种有效途径,其中一项重要内容是动力学缩比模型设计。本文以某型运载火箭为原型对象,首先根据其结构组成分别推导各部件的相似关系;然后,利用横向刚度和质量相似系数保持一致性,联立形成了运载火箭横向动特性相似关系;同时,考虑实际加工制造条件,分析了横向刚度和质量相似系数的约束;最后,根据上述相似关系和相似系数约束设计了1/5缩比模型,并对该缩比模型的动特性相似进行了有限元数值计算验证。验证结果表明,设计所得1/5缩比模型在动特性方面与原型具有较高的相似性,相关方法能够有效应用于运载火箭的动力学缩比模型设计。     

The Clausewitzian fallacy of absolute war

Clausewitz was much preoccupied with the apparent contradiction between real and absolute war. Why did war in history so rarely exhibit the extremes of violence and energy implied in the pure concept of war? Clausewitz’s commentators have usually followed him in thinking that this was a genuine problem in need of a solution, but I want to question that view. I will argue that Clausewitz did not have a coherent philosophy of absolute war, and therefore the contradiction he posited between real and absolute war was equally meaningless – as, too, was his effort to resolve it by claiming that some real wars approached or even attained the absolute form of war. The real problem was not the opposition of real and absolute war, but the self-contradictory theory of absolute war.     

基于累积前景理论的时间矩阵多属性综合评判模型

针对动态多属性方案排序优选决策问题,提出了一种基于累积前景理论的时间矩阵序列动态多属性综合评判系统模型。依据累积前景理论,将时间矩阵序列动态多属性决策转化为关于属性期望的益损时间矩阵序列动态决策,综合考虑各属性权重、各时间点的权重,计算各方案的最终综合前景值,并依据其大小对方案进行综合评判排序。最后给出了一个决策实例。