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71.
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Since the energy budget of mobile nodes is limited, the performance of a networking protocol for such users should be evaluated in terms of its energy efficiency, in addition to the more traditional metrics such as throughput. In this paper, two topology-unaware MAC protocols—in which the scheduling time slots are allocated irrespectively of the underline topology—are considered and their energy consumption is derived. It turns out that the per frame power consumption is lower for the less throughput-efficient protocol, suggesting that energy savings are achieved at the expense of throughput.A finer energy consumption study is carried out in the sequel, focusing on the amount of energy consumed to successfully transmit a certain number of packets, or equivalently, on the per successful transmission power consumption. It is shown that the more throughput-efficient protocol consumes less energy per successful transmission under certain conditions (which are derived), due to the lower number of transmission attempts before a data packet is successfully transmitted. The same energy-efficiency relation is observed under certain conditions (which are derived) when data packets are delay constrained and, thus, may become obsolete if not transmitted successfully within a specific time interval. The conditions under which the per successful transmission power consumption is minimized for delay-constrained packets, are also established in this work and it is observed that when the system throughput is maximized, the power consumed is close to the minimum. Simulation results support the claims and the expectations of the aforementioned analysis. 相似文献
73.
文章从居住社区的规划设计和建筑设计两方面以低能耗的角度分析了城市居住功能的分布、社区住宅建筑布局的合理性、社区景观设置的合理性以及停车、中水处理与被动式太阳能住宅建筑的相关先进生态理念,希望通过居住社区的生态可持续性设计改善社区的舒适性和能源的可持续性. 相似文献
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海洋钻井液有机物添加剂生物降解性评价 总被引:1,自引:0,他引:1
随着海洋石油的勘探开发,钻井液有机添加剂不可避免地进入海洋.因此在海洋勘探开发过程中应选择环保性能好,即生物降解性能好的有机物添加剂。用累计耗氧量法测定了海洋钻井液有机添加剂的生物降解性,研究评价了有机添加剂的生物降解规律和机理,探讨了有机物生物降解性同其化学结构的内在联系,为海洋勘探开发过程中选择环保性能好的有机物添加剂提供理论依据。总结实验结果发现:淀粉类(如DFD-140和FI-E1等)最容易生物降解;其次是纤维素类(如MV-CMC等)和烯类单体聚合物(如PAM和PHP);而沥青类、两性离子类则难以生物降解,有的甚至对生物降解起抑制作用。 相似文献
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本文对2002年国际国内白银市场做了全面分析,对2003年白银市场走势进行了分析预测。白银作为一种贵金属,同时又具有工业金属的特性,世界经济形势,世界政治局势的变化,都对白银价格走势产生影响。鉴于该金属的双重特性,本文就从白银的供应、需求、消费及世界经济的发展等方面论述白银市场前进趋势。 相似文献
78.
The non-fossil fuel obligation (NFFO), which consisted in a competitive auction for the deployment of renewable electricity, was the main policy for almost a decade in England and Wales. Once also used in Ireland and France, it has recently been abandoned in all countries. Many critics of the NFFO have focused on its inability to develop a national industry and promote a climate of stability among investors. This paper focuses on the incentives faced by developers bidding for a NFFO contract and shows that the low deployment rate under this scheme is likely to have been a predictable outcome of how the policy was structured and implemented rather than an unfortunate accident. The importance of the NFFO goes beyond the lack of an intense deployment of renewable electricity generation observed in the years in which the policy was on place. In fact, the NFFO has contributed to: promoting hostility against wind farms; creating false expectations of a price competitive renewable electricity sector; creating a playing field giving advantages to big players; preventing the creation of a wide renewable lobby coalition and the effective solution of planning constraints encountered by several renewable developers. 相似文献
79.
Conventional drying, dehumidification drying, and combined conventional-dehumidification drying of wood were experimentally studied in this article. The results showed that the energy consumption in the dehumidification drying is the least but its drying time is the longest. The energy consumption in the combined drying is more than that in the dehumidification drying but less than that in the conventional drying, and the drying time is half of that in the dehumidification drying. The advantages of the combined conventional and dehumidification drying are discussed from the experiments results. 相似文献
80.