Wireless network interface energy consumption

With the proliferation of mobile streaming multimedia, available battery capacity constrains the end-user experience. Since streaming applications are expected to be long running, wireless network interface card's (WNIC) energy consumption is particularly an acute problem. In this work, we explore various mechanisms to conserve client WNIC energy consumption for popular streaming formats such as Microsoft Windows media, Real and Apple Quicktime. First, we investigate the WNIC energy consumption characteristics for these popular multimedia streaming formats under varying stream bandwidth and network loss rates. We show that even for a high bandwidth 2000 kbps stream, the WNIC unnecessarily spent over 56% of the time in idle state; illustrating the potential for significant energy savings.Based on these observations, we explore two mechanisms to conserve the client WNIC energy consumption. First we show the limitations of IEEE 802.11 power saving mode for multimedia streams. Without an understanding of the stream requirements, these scheduled rendezvous mechanisms do not offer any energy savings for multimedia streams over 56 kbps. We also develop history-based client-side strategies to reduce the energy consumed by transitioning the WNICs to a lower power consuming sleep state. We show that streams optimized for 28.8 kbps can save over 80% in energy consumption with 2% data loss. A high bandwidth stream (768 kbps) can still save 57% in energy consumption with less than 0.3% data loss. We also show that Real and Quicktime packets are harder to predict at the network level without understanding the packet semantics. As the amount of cross traffic generated by other clients that share the same wireless segment increases, the potential energy savings from our client side policies deteriorate further. Our work enables multimedia proxy and server developers to suitably customize the stream to lower client energy consumption.     

一种无线传感器网络跨层能量模型及能耗计算

首先提出了一种基于无线传感器网络数据链路层的跨层能量模型。该能量模型考虑了网络层、物理层以及信道对能量损耗的影响。然后通过NS2仿真确定了模型中的重要因素对能耗的影响,并在此基础上推导了计算能耗的数学模型。最后通过对仿真结果的拟和得出模型中的参数,从而获得了能耗的计算公式。     

Designing buildings for minimal energy consumption

A dynamic model for predicting the thermal behaviour and energy consumption of a full-scale building has been developed. The model can include most of the design and climatological factors affecting the building. The time-dependent equation for the heat flow through the walls is converted into an implicit scheme and solved numerically. Special effort has been devoted to producing a model capable of aiding the architect during the various steps of building design, so as to approach thermal comfort with minimal energy consumption. The results are presented in graphical form, which allows the architect to detect easily the crucial factors in the thermal performance of the building.     

Modeling China's energy consumption behavior and changes in energy intensity

China's demand for energy has grown to fuel its rapidly expanding industrial, commercial and consumer sectors. At the same time, China has become the second largest consumer of petroleum products having surpassed Japan for the first time in 2003. The environmental consequences of a continuation of these trends will have global implications. Government policies and consumers have become more environmentally aware, but the ability of governments to formulate policies has been hindered by the lack of data on inter-factor and inter-fuel substitution possibilities. In this paper Allen partial elasticities of factor and energy substitution, and price elasticities of energy demand are calculated for China's industrial economy using a two-stage translog cost function approach for the period 1995–2004. The results suggest that energy is substitutable with both capital and labor. Coal is significantly substitutable with electricity and slightly complementary with oil, while oil and electricity are slightly substitutable. China's energy intensity is increasing during the study period and the major driver appears to be due to the increased use of energy-intensive technology.     

低功耗蓝牙模块能耗特征分析

煤矿电气设备可通过集成低功耗蓝牙模块,实现低功耗蓝牙通信功能,但在集成设计过程中,需要根据低功耗蓝牙模块的能耗特征设计电源保护电路、计算电池容量。针对该问题,在不同供电电压和射频功率下,采用高端电流监测芯片ZXCT1010对低功耗蓝牙模块在复位、初始化、广播、连接等不同工作状态下的能耗特征进行了分析。结果表明:低功耗蓝牙模块在射频收发时的能耗较大,且射频收发持续时间短,在射频静态时的能耗小,且射频静态持续时间长;低功耗蓝牙模块能耗受射频功率变化影响小,但受供电电压变化影响较大,供电电压越高,低功耗蓝牙模块各运行状态下的工作电流越大、能耗越大。因此,低功耗蓝牙模块集成应用时,应提供合适的供电电压,但无需限制射频功率。     

企业能耗过程性质判定及能量守恒性分析

为实现工业企业能源消耗过程行为和结构特性的分析,在企业能耗过程模型的基础上,研究了与模型相关的动态性质与结构性质,并有针对性地分析了网系统的能量守恒性。为实现生产中各物质流的动态逻辑关系以及工艺流程静态拓扑结构的描述,提出了动态与静态关联矩阵的概念并分别给出定义;分别研究了与动态行为有关的动态平衡量、稳态运行区间等性质;在模型加权守恒性研究的基础上,提出了一种基于S不变量的网系统能量守恒性计算方法并延伸出对设备与产品能效的分析计算。分析表明,方法有助于实际能源消耗过程中物料平衡性、产品或原料积压以及产品能效等特性的分析与检查。     

蜂窝异构网络能量消耗的研究

宏蜂窝和小蜂窝混合的异构网络必然将会成为一种满足日益增长的移动业务量需求的手段。然而,大规模部署小蜂窝接入点(SAPs)也会导致相当大的能量消耗的增长,随着环境意识的增强和能源价格的提高,为宏蜂窝和小蜂窝设计高能效的无线系统至关重要。本文研究了认知SAPs的一种分布式睡眠模式策略,利用随机几何工具,得出SAP的用户发现性能,并得到位于一个宏蜂窝基站Voronoi小区中的小蜂窝的上行链路容量以及系统总的网络能量消耗。     

起重机能耗监测节点设计

针对采用有线传输技术监测起重机能耗状态难度较大的问题,提出一种基于无线传感网络的能耗监测节点设计方案。该节点采用基于ZigBee技术的CC2430芯片作为主控芯片,实现了起重机能耗数据的实时采集与无线传输,具有能耗低、成本低、抗干扰能力强及适应能力强等优点。     

基于能耗的分簇频谱感知方法

在协作频谱感知中,当信道经历衰落和阴影时,各用户的感知性能会有不同程度影响,某些受影响严重的次用户甚至可能会严重影响到整个感知网络的性能.同时参与协作的用户数越多,认知传感器网络面临的问题越大.为了解决这些问题,提出了一种基于能耗的分簇协作感知算法.该算法引入基于节点能量的LEACH分簇算法,将认知传感器网络中的各个节点按该分簇算法分入若干簇内;在每个簇内,构造了同时考虑检测性能和能量消耗的效用函数,基于该效用函数对最佳协作用户数和用户进行选择,使每个簇内的检测性能和能耗达到很好的折中;在汇聚节点运用OR规则将簇头发送过来的感知信息进行融合,得到最终判决结果.仿真结果表明,该基于能耗的分簇协作频谱感知算法可以有效地延长认知传感器网络的生存时间,节省网络的能耗,并且保证良好的检测性能.     

聚乙二醇生产装置用能优化研究

对聚乙二醇生产装置的用能问题进行了研究,重点讨论了反应热的回收利用和换热系统的优化.采用时间分段法分析了装置的用能特征,针对间歇操作的特点,提出了利用中间热储罐进行间接热回收的改进工艺,并通过绘制间歇过程冷热物流组合曲线确定了中间热储罐的温位及可回收的热量.研究表明,应用本文方法可实现反应热的回收,工艺能耗显著降低,节能达69%以上.     

无线传感器网络中能耗问题的探讨

无线传感器网络中传感节点能量消耗不均衡将导致整个网络过早地失效。文章在LEACH层次路由算法的基础上,提出了自动退避的簇头竞争选择机制、设定阀值的数据融合和基于能量感知的多路径策略,并在网络均衡、能量消耗方面做了优化,极大地提高了传感节点的服务寿命,延长了整个网络的生存周期。     

基于能耗优化的AODV路由协议

在无线传感器网络中,为了优化和平衡各节点的能量消耗从而达到延长了网络寿命的目的,提出了一种基于能耗优化的AODV(E-AODV)路由协议。E-AODV优先选择剩余能量较高的节点参与路由同时选择能耗相对较小的路径作为路由,引进了被动更新路由和动态调整发射功率两种机制。NS-2仿真结果表明:与传统AODV相比,E-AODV降低了网络的整体能耗,有效均衡使用各节点的能量,延长了网络寿命。     

矿用终端节点能耗研究

通过分析CC2530的低功耗模式以及基于ZigBee协议的Z-Stack协议栈的休眠与唤醒机制,设计了一种基于CC2530的矿用无线传感器网络终端节点。采用基于福禄克万用表测量的实测方法,测试该终端节点的能耗,得出结论:终端节点与协调器建立连接时消耗的电流最大,在休眠与唤醒模式下电流消耗较小;终端节点的平均工作电流受发射功率影响较小;终端节点的休眠周期直接影响电流消耗,周期越长,则能耗越低。     

数据中心网络拓扑感知型能耗优化算法

针对数据中心网络中高能耗的问题,提出了一种拓扑感知型能耗优化算法。算法首先根据广义超立方体拓扑多维正交和单维全连接的结构特性,优化虚拟机的部署位置,进而提出多维最佳适应策略来充分利用服务器各维资源。然后利用虚拟机资源需求预测模型并结合迁移代价公式,均衡考虑服务器资源使用代价、虚拟机通信代价和迁移资源消耗,在合理迁移虚拟机以满足系统性能的前提下,降低了网络的能耗并且缓解了网络链路的拥塞。最终将网络的能耗优化问题转化成虚拟机在服务器上的优化配置问题。实验结果表明,与其他三种算法比较,算法在降低系统能耗和减少拥塞方面获得了良好的效果。     

工业机器人能耗优化方法研究综述

机器人技术作为智能制造的关键,其能耗问题已引起各制造业大国的关注,国内外的研究十分活跃。针对工业机器人能耗优化问题,介绍了轻量化设计、高效驱动系统设计、能量存储和共享装置等低能耗硬件设计方法,从轨迹规划和任务调度方面对能耗优化的软件方法进行了综述,介绍了具有应用潜力的软件优化和硬件相结合的混合方法,同时突出了主要研究成果并说明了不足之处;最后指出工业机器人能耗优化具有潜力的发展趋势。     

低能耗听觉优化产品的设计

结合用户需求进行科技创新,设计以骨传导技术为核心的低能耗听觉优化产品.产品由骨传导模块、USB转DC充电模块、蓝牙连接模块和储电模块组成,采用BLE蓝牙低能耗技术.在对现有骨传导技术的改进和创新基础上,通过对听觉产品的配方改进,实现了通过牙齿咬合传递音频的创新设计.     

Measuring mobile phone energy consumption for 802.11 wireless networking

The complexity of modern mobile phones makes it difficult for developers to understand the power consumption of their applications. Our measurement framework produces fine-grained, annotated traces of a phone’s power consumption which we are using to develop an understanding of how particular aspects of an application drive energy use. We ran a large number of automated tests using Google Android G1, Magic, Hero and Nexus handsets and present results for the average energy consumption of connection and data transmission over 802.11 wireless networks. Our results show that the optimal choice of data transmission strategy is different between handsets, operating systems, and device context.