Speculation and volatility spillover in the crude oil and agricultural commodity markets: A Bayesian analysis

This paper assesses factors that potentially influence the volatility of crude oil prices and the possible linkage between this volatility and agricultural commodity markets. Stochastic volatility models are applied to weekly crude oil, corn, and wheat futures prices from November 1998 to January 2009. Model parameters are estimated using Bayesian Markov Chain Monte Carlo methods. Speculation, scalping, and petroleum inventories are found to be important in explaining the volatility of crude oil prices. Several properties of crude oil price dynamics are established, including mean-reversion, an asymmetry between returns and volatility, volatility clustering, and infrequent compound jumps. We find evidence of volatility spillover among crude oil, corn, and wheat markets after the fall of 2006. This can be largely explained by tightened interdependence between crude oil and these commodity markets induced by ethanol production.     

单芯片10G EPON ONU发力中国市场

预计到2014年,互联网容量将比2009年扩大4倍;随着越来越多的客户订购高清IPTV业务以及越来越多的服务提供商增加按需视频点播(VOD)业务,住宅接入网络所需的带宽也将持续增加,需求也将激增至500M。有线和无线通信领导厂商Broadcom(博通)公     

Analytical modeling of bidirectional multi‐channel IEEE 802.11 MAC protocols

This paper presents an analytical approach to model the bi‐directional multi‐channel IEEE 802.11 MAC protocols (Bi‐MCMAC) for ad hoc networks. Extensive simulation work has been done for the performance evaluation of IEEE 802.11 MAC protocols. Since simulation has several limitations, this work is primarily based on the analytical approach. The objective of this paper is to show analytically the performance advantages of Bi‐MCMAC protocol over the classical IEEE 802.11 MAC protocol. The distributed coordination function (DCF) mode of medium access control (MAC) is considered in the modeling. Two different channel scheduling strategies, namely, random channel selection and fastest channel first selection strategy are also presented in the presence of multiple channels with different transmission rates. M/G/1 queue is used to model the protocols, and stochastic reward nets (SRNs) are employed as a modeling technique as it readily captures the synchronization between events in the DCF mode of access. The average system throughput, mean delay, and server utilization of each MAC protocol are evaluated using the SRN formalism. We also validate our analytical model by comparison with simulation results. The results obtained through the analytical modeling approach illustrate the performance advantages of Bi‐MCMAC protocols with the fastest channel first scheduling strategy over the classical IEEE 802.11 protocol for TCP traffic in wireless ad hoc networks. Copyright © 2010 John Wiley & Sons, Ltd.     

3G智能机器人的研究

随着3G通讯技术、物联网技术、机电控制技术、多媒体技术的日趋成熟,基于相关技术的产品也备受消费者的欢迎.本文结合当前机器人技术和嵌入式技术的融合发展方向,提出了一种基于ARM9与3G网络相结合的智能机器人,给出了系统结构设计,硬件模块设计,软件设计等.     

基于车联网的交通流云处理平台研究

Internet of Car, resulting from the Internet of Things , is a key point for the forthcoming smart city. In this article, GPS technology, 3G wireless technology and cloudprocessing technology are employed to construct a cloudprocessing network platform based on the Internet of Car. By this platform, positions and velocity of the running cars , information of traffic flow from fixed monitoring points and transportation videos are combined to be a virtual traffic flow data platform, which is a parallel system with real traffic flow and is able to supply basic data for analysis and decision of intelligent transportation system.     

建设全媒体科普视窗创新科普手段

全媒体、3G网络、LED显示屏等新技术的兴起给科学技术传播工作带来了全新的机遇和挑战。本文以新型科普设施"全媒体科普视窗"的研发、应用和推广为主线,探讨了新形势下依靠科技手段创新科普传播方式的意义与途径,并阐述了以全媒体科普视窗为基础的科普服务体系的建设,以及需要注意的问题和相应的解决方法。     

构建更加开放的移动互联网

随着HSPA+等网络的部署,移动互联网业务将进一步丰富,移动通信与互联网将会融合出更大的产业。文章探讨移动互联网的现状、发展趋势,并对运营商部署移动互联网业务提出了相关建议。     

2G向3G迁移策略研究

通过对日本3G十年发展历程分析,研究3G发展的客观规律,预测国内2G到3G迁移可能经历的阶段和各阶段的主要特征,并分析日本运营商2G到3G迁移发展经验和目前国内运营商采取的差异化策略,以期对国内运营商有步骤地实施3G迁移提供参考。     

基于ARM的3G无线射频测控平台设计与应用

介绍了一种3G无线射频测控平台设计方法。将华为3G无线模块与HID读卡器统一于ARM微处理器硬件平台,可满足大范围分散地域的多种测控需求。在此基础上,设计了可兼容WEIGAND26和WEIGAND34协议的读卡程序、3G无线通信程序和其他软件。在分散于湛江地区的多个移动营业厅实地应用表明,该设备读卡正确率高、响应快,数据存储和无线传输稳定可靠。     

基于3G-WLAN交互系统的物联网研究

文中介绍了3G-WLAN网络和物联网的概念和关键技术,设计出3G-WLAN交互系统网络,并把交互系统和物联网相结合,研究出3G网络、WLAN网络与物联网融合的系统架构.融合的系统充分利用了3G网络、WLAN网络的优势,提高物联网的安全性、稳定性和效率.