Retailer's rationale to refuse consumer returns in supply chains

While accepting consumer returns has long been proposed as a solution to resolve the consumer valuation uncertainty problem, there are still a sizable portion of retailers who insist on a “no return” policy. In this article, we offer an economic rationale for these seemingly unreasonable strategies in a supply chain context. We demonstrate when and why the retailer may benefit from refusing consumer returns, even though offering consumer returns allows the supply chain to implement the expostmarket segmentation. Granting the retailer the right to refuse consumer returns may sometimes improve supply chain efficiency: it eliminates the manufacturer's attempt to induce inefficient consumer returns and bring the equilibrium back to that in the vertically integrated benchmark. We also find that the refund and the retail price can move in the opposite directions when product reliability varies, and consumer returns have a nontrivial impact on the quality choice. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 686–701, 2015     

时滞细胞神经网络的代数抗饱和补偿设计

针对时滞细胞神经网络,提出了一种基于代数判据的抗饱和补偿设计。运用M矩阵理论、迪尼导数、系统参数设计了无饱和输入限制系统镇定的代数判据。在此基础上,利用不等式放缩原理、分区讨论与大中取大综合方法和Lyapunov理论,得出了二次矩阵不等式形式的抗饱和控制设计方案,进而将之转化为线性矩阵不等式。同时,给出了吸引域及其最大化方法。仿真验证了该设计方案的可行性和有效性。     

基于AIS的对海雷达多目标联合误差估计方法

提出了一种基于AIS的对海警戒雷达多目标联合误差估计方法,该方法以高精度AIS提供的目标信息为目标真值,对雷达进行误差估计。利用系统积累的多目标航迹信息,首先进行目标粗关联,将航迹信息进行时空对准后产生误差序列,通过单目标误差序列统计信息进行异常值的筛选,再通过多目标误差序列进行错误关联目标的检验,最终对剩余误差序列进行误差估计。通过实测数据和实际应用证明,该方法估计的雷达误差较准确,用估计结果对雷达误差进行校准后可有效减小对海雷达的系统误差。     

协同作战中信息分发算法研究

大规模协同作战中的高效通信问题为当前信息战的研究重点之一,但由于单独作战单元无法了解全局的信息内容及需求方,这给通信资源有限的参战兵力之间的态势共享带来了困难。为此提出了一个分布式协作信息分发算法,在理论上借鉴了复杂网络的小世界特性,即单元节点可以通过邻节点在较少跳数内完成信息的传输。在思路上利用了信息相关性概念,作战单元利用信息之间的关联性及信息与节点之间的收发关系建立控制信息发送的路由表。并通过仿真实验验证了不同网络拓扑下算法性能的变化情况,结果证明分发算法能较好地支持信息共享。     

PID调节下H桥式逆变器离散建模及分岔现象

为研究PID调节下H桥式逆变器的非线性行为,选取逆变器输入电压为分岔参数,利用频闪映射法推导出PID调节下H桥式逆变器的离散数学模型.使用Matlab编程得到系统输出电流随输入电压变化的动态分岔图,通过数值仿真验证了离散数学模型的正确性.仿真结果表明频闪映射法适用于建立H桥式逆变器的离散数学模型;PID调节下H桥式逆变器存在分岔行为.研究结果可为建立PID调节下H桥式逆变器的离散数学模型提供参考.     

Return policy: Hassle‐free or your money‐back guarantee?

This article compares the profitability of two pervasively adopted return policies—money‐back guarantee and hassle‐free policies. In our model, a seller sells to consumers with heterogeneous valuations and hassle costs. Products are subject to quality risk, and product misfit can only be observed post‐purchase. While the hassle‐free policy is cost advantageous from the seller's viewpoint, a money‐back guarantee allows the seller to fine‐tune the consumer hassle on returning the product. Thus, when the two return policies lead to the same consumer behaviors, the hassle‐free policy dominates. Conversely, a money‐back guarantee can be more profitable even if on average, high‐valuation consumers experience a lower hassle cost than the low‐valuation ones. The optimal hassle cost can be higher when product quality gets improved; thus, it is not necessarily a perfect proxy or signal of the seller's quality. We further allow the seller to adopt a mixture of these policies, and identify the concrete operating regimes within which these return policies are optimal among more flexible policies. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 403–417, 2014     

金属体在海水中运动产生的感应电场建模

分析了金属体在海水中运动产生感应电场的机理。采用镜像法推导了水下垂直和水平直流电流元在海水中的电场表达式,进一步导出了海水中运动金属体切割地磁场而在海水中产生的感应电场数学模型,并计算分析了运动金属体的感应电场大小及空间分布。仿真计算结果表明,20m长的金属椭球体,以4m/s的航速在水下10m航行时,在水下30m左右感应电场的量级为nV/m,并且该电场在空间分布上有明显的特征。     

采用波数域方法分析细长柱壳的振动与声辐射特性

采用波数域方法对细长柱壳进行振动与辐射噪声分析。在获得细长柱壳表面振动后,法向振动在波数域展开为波数谱,结构振动波数特征由此得以直观展现,与辐射噪声相关的有效振动量得以定量给出。对细长柱壳的波数谱分析表明:低阶周向波数振动是其参与有效声辐射的主要成分,通过不等间距分舱可以在一定程度上控制有效声辐射振动级,从而控制结构的噪声辐射,但对整体呼吸运动的振动则效果不显著。     

D0影响亚硝酸型SND工艺的机理探讨

亚硝酸型SND污水生物脱氮新工艺因兼具短程硝化和同时硝化反硝化工艺的优势而具有很强的开发潜力。在介绍亚硝酸型SND工艺特点之后,着重从微环境理论、微生物特性及化学计量学等角度较为深入地探讨了溶解氧浓度(DO)影响亚硝酸型SND工艺脱氮效果的机理,从理论上进一步证实了DO对于亚硝酸型SND工艺的重要性。     

Mechanical behavior and failure mechanism of polyurea nanocomposites under quasi-static and dynamic compressive loading

Polyurea is an elastomeric material that can be applied to enhance the protection ability of structures under blast and impact loading.In order to study the compressive mechanical properties of SiC/polyurea nanocomposites under quasi-static and dynamic loading,a universal testing machine and split Hop-kinson pressure bar(SHPB)apparatus were used respectively.The stress-strain curves were obtained on polyurea and its composites at strain rates of 0.001-8000 s-1.The results of the experiment suggested that increase in the strain rates led to the rise of the flow stress,compressive strength,strain rate sensitivity and strain energy.This indicates that all of the presented materials were dependent on strain rate.Moreover,these mechanical characters were enhanced by incorporating a small amount of SiC into polyurea matrix.The relation between yield stress and strain rates were established using the power law functions.Finally,in order to investigate the fracture surfaces and inside information of failed specimens,scanning electron microscopy(SEM)and micro X-ray computed tomography(micro-CT)were used respectively.Multiple voids,crazes,micro-cracks and cracking were observed in fracture surfaces.On the other hand,the cracking propagation was found in the micro-CT slice images.It is essential to understand the deformation and failure mechanisms in all the polyurea materials.