ENO格式应用分析

对一类高阶、高分辨率的ENO格式进行了较为详细的讨论。通过一些典型算例的应用和同常用TVD类型格式的比较 ,说明了在计算中采用高阶格式分辨复杂流动结构的优越性。在对格式应用分析的基础上 ,指出了格式应用中需注意的问题。通过定量分析说明 ,高阶ENO格式在计算中 ,不但能够减少网格规模 ,而且能够明显提高计算物理量 ,特别是其导数的计算精度     

双谱特征在水下目标自动识别中的应用

非高斯信号处理是信号处理的一个新领域。以舰船辐射噪声为主的噪声具有很强的非高斯性和非线性性。由此可利用信号双谱,提取舰船辐射噪声信号的非高斯成份。实验结果表明,高阶谱在声纳目标识别方面具有很大的发展潜力     

Coherent systems based on sequential order statistics

The sequential order statistics (SOS) are a good way to model the lifetimes of the components in a system when the failure of a component at time t affects the performance of the working components at this age t. In this article, we study properties of the lifetimes of the coherent systems obtained using SOS. Specifically, we obtain a mixture representation based on the signature of the system. This representation is used to obtain stochastic comparisons. To get these comparisons, we obtain some ordering properties for the SOS, which in this context represent the lifetimes of k‐out‐of‐n systems. In particular, we show that they are not necessarily hazard rate ordered. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

Managing components for assemble‐to‐order products with lead‐time‐dependent pricing: The full‐shipment model

We study a component inventory planning problem in an assemble‐to‐order environment faced by many contract manufacturers in which both quick delivery and efficient management of component inventory are crucial for the manufacturers to achieve profitability in a highly competitive market. Extending a recent study in a similar problem setting by the same authors, we analyze an optimization model for determining the optimal component stocking decision for a contract manufacturer facing an uncertain future demand, where product price depends on the delivery times. In contrast to our earlier work, this paper considers the situation where the contract manufacturer needs to deliver the full order quantity in one single shipment. This delivery requirement is appropriate for many industries, such as the garment and toy industries, where the economies of scale in transportation is essential. We develop efficient solution procedures for solving this optimization problem. We use our model results to illustrate how the different model parameters affect the optimal solution. We also compare the results under this full‐shipment model with those from our earlier work that allows for multiple partial shipments. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

钛酸铅晶体反铁电相至电场感应铁电相相变的研究

仔细研究了PbTiO3电场感应铁电相的晶体结构。在初始反铁电相中,各离子位移方向与极轴垂直,但在外电场感应下,Pb离子沿极轴方向有相同方向0.17的位移,从而使晶体呈现铁电相特征,发生反铁电-铁电相变。此铁电相称之为电场感应铁(EFI)电相。通过结构对称性分析,确定EFI铁电相的对称性是C2mm(C2v),用极矢量Ps作为序参量来描述相变时对称性的变化是合适的。     

(Re-)emergent orders: understanding the negotiation(s) of rebel governance

Abstract

The concept of order is often neglected in the study of conflict – seemingly such a ‘disordering’ process. With the recent increase in the examination of rebel governance however, bringing order back into our understanding of rebel and insurgent groups has much to offer in exploring the everyday politics which connect authorities, rebel movements and the population itself, in a complex mass of intersubjective and power-based interactions and negotiations. Rebels both shape and are shaped by existing forms of order in complex and ongoing ways. This article explores how varying elements interact in the negotiation, framing and enforcement of order and develops an original analytical framework to examine the perpetual negotiations of rebel movements in their attempts to cement their control.     

Rebels & Legitimacy; An Introduction

Abstract

This introduction to the double special issue on the theme of rebels and legitimacy aims to set out the parameters for the discussion. It looks at legitimacy as a concept and at legitimation as a process. To date most of the literature on legitimacy has focused on the state. However, rebel groups such as insurgents, terrorists, warlords and guerrillas have all had claims, and continue to claim, legitimacy as well. How and when are these rebels seen as legitimate actors? Existing suggestions of rebel legitimacy focus heavily on state models of social order and the social contract. This first contribution discusses how to conceptualize legitimacy and how to make it operational. A two-pronged approach, borrowing heavily from Max Weber, is proposed. Legitimacy is investigated based on beliefs and belief systems about what is considered legitimate. This is combined with practices whereby legitimacy is enacted, copied and emulated by the population the rebels claim to represent.     

正弦波调制的光纤环本征频率测量方法

为了弥补传统光纤环本征频率测量方法中方波调制存在死区的缺陷,提出正弦波调制的本征频率测量方法。对正弦波调制下的光纤陀螺输出信号进行分析,得到二次谐波幅度与调制频率间的二次函数关系,通过计算抛物线顶点即可求得本征频率。依据该原理对已有的光纤陀螺进行升级改造,研制了一套本征频率测量系统。试验结果表明:该方法可达到1×10-5的测量精度,是一种成本低、精度高的光纤环本征频率测量方法。     

PMSM位置伺服系统新型融合控制策略

针对PMSM位置伺服系统存在非线性、强耦合等特征,提出了一种基于分数阶PID和分数阶滑模控制的新型融合控制策略。通过检测位置误差、速度及负载转矩,归一化处理后带入构造的二次性能指标函数,根据其数值动态改变分数阶PID和分数阶滑模控制器输入到被控对象控制量的权重值大小,从而确保提出的新型融合控制策略具有快速跟踪和抗扰动能力。数值仿真实验结果表明:新型融合控制策略比分数阶PID和分数阶滑模控制拥有优良的动静态性能和较好的鲁棒性。     

舰艇编队协同作战的空中目标威胁评估研究

从系统分析舰艇编队协同作战的空中目标威胁评估问题入手,深入研究了协同作战环境下编队空中目标威胁评估的基本过程。在此基础上,针对编队协同决策的特点,建立了基于两层决策的协同作战环境下编队空中目标威胁评估模型,从而提出了舰艇编队协同作战的空中目标威胁评估方法。最后,通过实例说明了所提方法的有效性。