车联网中基于距离的多转发者广播协议

为实现安全信息在车载自组织网络中快速、有效的传播,提出一种基于距离的多转发者广播协议.将上一跳转发节点信号边缘处的节点作为最优转发节点,以增加单次转发覆盖新节点的数量.选择信号覆盖范围中点处节点和次接近信号覆盖范围边缘处节点作为备选转发节点,以降低因隐蔽站或车辆脱离信号覆盖范围导致转发失败的概率,并通过反向车辆存储转发广播分组恢复路由.仿真结果表明,该协议能够适应多种车辆密度的车载自组织网络,满足不同交通流密度情况下紧急信息的分发要求,降低车辆间通信的平均端到端延时和转发率,提高转发效率,并且负载上升缓慢,能有效抑制广播风暴.     

A study of detecting and combating cybersickness with fuzzy control for the elderly within 3D virtual stores

Elderly individuals can access online 3D virtual stores from their homes to make purchases. However, most virtual environments (VEs) often elicit physical responses to certain types of movements in the VEs. Some users exhibit symptoms that parallel those of classical motion sickness, called cybersickness, both during and after the VE experience. This study investigated the factors that contribute to cybersickness among the elderly when immersed in a 3D virtual store. The results of the first experiment show that the simulator sickness questionnaire (SSQ) scores increased significantly by the reasons of navigational rotating speed and duration of exposure. Based on these results, a warning system with fuzzy control for combating cybersickness was developed. The results of the second and third experiments show that the proposed system can efficiently determine the level of cybersickness based on the fuzzy sets analysis of operating signals from scene rotating speed and exposure duration, and subsequently combat cybersickness.     

Optimal pricing decisions for an omni‐channel supply chain with retail service

Motivated by the emergence of dominant physical stores utilizing a buy‐online‐and‐pickup‐in‐store (BOPS) channel, we examine the interaction of such a stronger retailer and a manufacturer's strategies on the pricing and service value. The dominant retailer provides an added service value to end consumers by the traditional channel and BOPS option, which has a positive influence on the market demand. The manufacturer makes the channel selection decision between a dual channel and an omni‐channel. We formulate a retailer Stackelberg game and characterize the equilibrium pricing and service solutions under centralized and decentralized cases. Our results indicate that the service value of a physical store strongly influences the players' pricing strategies. The sensitivity analysis reveals that the total revenue of the supply chain increases with the market scale expansion coefficient of the BOPS option. Furthermore, the result suggests that offering the BOPS channel is always an effective initiative to boost supply chain performance, especially in the centralized structure.     

The impact of goods-classification and landmarks for spatial knowledge and goods-finding in the elderly within a 3D virtual store

Online shopping has become quite popular since its first arrival on the internet. Although numerous studies have been performed to investigate various issues related to the internet store, some research issues relating to the spatial cognition of the elderly (the fastest growing internet group) when exploring a 3D virtual store still await further empirical investigation. The objective of this study was to examine how elderly users acquire spatial knowledge in an on-screen virtual store. Specifically, the impact of different types of landmarks on the acquisition of spatial knowledge was examined. In addition, in this study, goods-classification was seen as an implicit landmark associated with the acquisition of spatial knowledge. Therefore, it is worth observing the impact during the location of the goods and examining the combined effect with landmarks. The experimental results indicated that landmarks are important for the elderly as they attempt to locate goods within a 3D virtual store, no matter what types are used. However, landmarks are not the only resources for constructing spatial knowledge in a 3D virtual store; the classification of goods is also a good resource and may be more important than landmarks. In addition, the combined effect of goods-classification and landmarks in a 2D image would be best for the elderly in terms of acquired spatial cognition and the location of goods within a 3D virtual store.     

SSDKV:一种SSD友好的键值对存储系统

当前大量键值对(Key-Value)存储系统使用固态硬盘(SSD)改善系统的I/O响应速度。但是现有的键值对存储系统应用程序使用标准文件系统处理数据在固态硬盘上的存储,这对应用程序而言底层固态盘的物理特性被屏蔽,同时固态盘也无法针对应用程序的特定I/O模式进行优化,使得基于固态盘的键值对系统性能没有得到充分发挥。针对此问题,设计了同时考虑键值对应用程序存取行为和SSD存储器访问特性的存储管理模块,并与LevelDB结合实现了一种轻量级的、将上层应用与底层存储集成一体的键值对系统—SSDKV。它提供键值对接口给外部程序,结合键值对数据的特点构造适应SSD的数据布局。SSDKV简化了传统文件系统对键值对数据的额外处理,并根据键值对数据的类型及其存取模式对SSD存储空间进行有效管理,使得基于SSD设备的键值对系统性能进一步提高。通过基准程序测试,与运行于传统文件系统上的LevelDB相比,SSDKV使得写性能提高达4倍,读性能提高达1.5倍。     

A convergence of key‐value storage systems from clouds to supercomputers

This paper presents a convergence of distributed key‐value storage systems in clouds and supercomputers. It specifically presents ZHT, a zero‐hop distributed key‐value store system, which has been tuned for the requirements of high‐end computing systems. ZHT aims to be a building block for future distributed systems, such as parallel and distributed file systems, distributed job management systems, and parallel programming systems. ZHT has some important properties, such as being lightweight, dynamically allowing nodes join and leave, fault tolerant through replication, persistent, scalable, and supporting unconventional operations such as append, compare and swap, callback in addition to the traditional insert/lookup/remove. We have evaluated ZHT's performance under a variety of systems, ranging from a Linux cluster with 64 nodes, an Amazon EC2 virtual cluster up to 96 nodes, to an IBM Blue Gene/P supercomputer with 8K nodes. We compared ZHT against other key‐value stores and found it offers superior performance for the features and portability it supports. This paper also presents several real systems that have adopted ZHT, namely, FusionFS (a distributed file system), IStore (a storage system with erasure coding), MATRIX (distributed scheduling), Slurm++ (distributed HPC job launch), Fabriq (distributed message queue management); all of these real systems have been simplified because of key‐value storage systems and have been shown to outperform other leading systems by orders of magnitude in some cases. It is important to highlight that some of these systems are rooted in HPC systems from supercomputers, while others are rooted in clouds and ad hoc distributed systems; through our work, we have shown how versatile key‐value storage systems can be in such a variety of environments. Copyright © 2015 John Wiley & Sons, Ltd.     

服装品牌概念向大众认知转换的机制

本文基于对国内外服装品牌的概念营销的关注,分析了服装品牌概念向大众认知转换的关键因素,指出服装品牌基于注意力导向进行概念营销的特征。重点通过对转换的介入点、途径、方法的分析,构架了转换的机制。     

带软时间窗的两阶段连锁门店配送车辆路径问题研究

针对连锁企业配送路径优化决策问题,利用分解法进行两阶段分析,建立数学模型,并引入时间窗约束。应用最小包络聚类分析方法确定供应商与配送中心的最佳位置与数量,运用禁忌搜索算法求解配送中心到门店的最佳配送路径,算例测试验证了该方法的有效性与研究的实用价值。     

基于C++的Windows CE文件I/O处理技术

通过对Windows文件系统的分析以及各种文件I／O处理方法的进一步研究,发现大多数Windows CE应用程序的文件I/O处理都是使用基于Win32 API函数的方法或基于MFC类库中CFile类的方法,本文讨论了这两种文件处理方法的基本原理及其运用。     

Quick response and omnichannel retail operations with the ship‐to‐store program

To better integrate online businesses with offline stores, fast‐fashion retailers roll out the “ship‐to‐store” (STS) initiative, which is an omnichannel fulfillment method that allows consumers to order online and have their parcels delivered to selected stores for pickup. To study the impact of STS on fast‐fashion operations, we consider four scenarios: multichannel retailing, multichannel retailing with quick response (QR), omnichannel retailing with STS, and omnichannel retailing with both STS and QR. Moreover, we investigate how STS influences the value of QR. The results show that although STS benefits firms in many situations, STS under a QR strategy can reduce a retailer's profits when inventory information disclosure due to STS dampens cross‐selling opportunities. Our findings also reveal that the implementation of STS may lower the value of QR when customers who encounter stockouts offline opt to purchase online directly rather than use STS.