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51.
The development of future mobile networks will be driven, in large part, by content and web based services. In this paper,
we examine several performance, scalability and architectural challenges faced by future mobile web applications and how advanced
mobile content delivery techniques can address these challenges. We review existing content delivery using a taxonomy that
consists of three categories: network scaling, end system acceleration, and content and protocol optimization. While wireline
content delivery focuses on network and server scalability, mobile content delivery will likely benefit most from optimizing
radio link usage. We also present our ongoing work in this area, which extends the functionality of edge caching to the terminal,
uses user interest correlation information to maintain low terminal power consumption and adds a new dimension to radio resource
management.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
52.
The distribution of ergosterol in different parts of shiitake mushrooms was studied in order to optimize the conversion of ergosterol to vitamin D2 during drying. The effect of moisture on the conversion of ergosterol to vitamin D2 was also investigated by adjusting the moisture content of fresh mushrooms to different levels in a large vacuum desiccator and subjecting them to UV irradiation at 290-320 nm wavelength, for 2 h. The moisture, ergosterol and vitamin D2 contents were determined using standard procedures. It was found that the ergosterol content on a dry matter basis of fresh shiitake mushroom was highest in the gills (10.6 ± 0.99 mg/g DM), followed by the cap or pileus (5.34 ± 0.64 mg/g DM) and was least in the stalk or stipe (2.97 ± 0.56). The moisture content had a marked influence on the conversion of ergosterol to vitamin D2, the best conversion taking place at a moisture content of about 70% on a wet basis. 相似文献
53.
M. Safar D. Bertrand P. Robert M. F. Devaux C. Genot 《Journal of the American Oil Chemists' Society》1994,71(4):371-377
The combination of attenuated total reflectance (ATR) and mid-infrared spectroscopy (MIRS) with statistical multidimensional
techniques made it possible to extract relevant information from MIR spectra of lipid-rich food products. Wavenumber assignments
for typical functional groups in fatty acids were made for standard fatty acids: Absorption bands around 1745 cm−1, 2853 cm−1, 2954 cm−1, 3005 cm−1, 966 cm−1, 3450 cm−1 and 1640 cm−1 are due to absorption of the carbonyl group, C−H stretch, =CH double bonds of lipids and O−H of lipids, respectively. In
lipid-rich food products, some bands are modified. Water strongly absorbs in the region of 3600–3000 cm−1 and at 1650 cm−1 in butters and margarines, allowing one to rapidly differentiate the foods as function of their water content. Principal
component analysis was used to emphasize the differences between spectra and to rapidly classify 27 commercial samples of
oils, butters and margarines. As the MIR spectra contain information about carbonyl groups and double bonds, the foods were
classified with ATR-MIR, in agreement with their degree of esterification and their degree of unsaturation as determined from
gas-liquid chromatography analysis. However, it was difficult to differentiate the studied food products in terms of their
average chainlength. 相似文献
54.
The spatiotemporal aspects of the Portevin–Le Chatelier effect in Al–Mg alloys are investigated using direct observations of the sample surface with a digital camera. Optical measurements of the surface profile using a white light interferometer allow the estimation of the local strain and strain rate associated with the bands. The effect of Mg content on instability characteristics is analyzed. The reloading time is shown to depend on the Mg content only at the strain and strain rates where type C bands are observed. 相似文献
55.
详细地论述了霍林河一号露天矿各煤层的灰分特征和同一煤层不同地段灰分的变化情况,揭示了各煤层灰分的变化规律,为露天开采提供了可靠的技术保证。 相似文献
56.
Low carbon steel was oxidized over the temperature range 1000‐1250°C in O2‐CO2‐H2O‐N2, O2‐H2O‐N2, and O2‐CO2‐N2 gas mixtures. Oxidation times were 12‐120 min. and the scales were 50‐2000 μm thick. The variations of these parameters were chosen to elucidate the phase composition of oxide scales under conditions similar to those of reheating furnaces in hot strip mills, using either thin slab casting or conventional casting and rolling technology. Two types of scales have been observed which are influenced by the furnace atmosphere, oxidation time, and temperature. The first type is a crystalline scale with an irregular outer surface, composed mostly of wustite (FeO), and a negligible amount of magnetite (Fe3O4). The second type is the classical three‐layer scale, composed of wustite (FeO), magnetite (Fe3O4), and hematite (Fe2O3). In general, the experiments showed that an increase in oxidation time decreased the percentage of wustite while the percentages of magnetite and hematite increased. A rise in oxygen concentration in the gas mixture increased the percentages of magnetite and hematite, confirming earlier experimental findings. In water vapour‐free atmospheres O2‐CO2‐N2, the oxide scales had a low percentage of wustite, and high percentage of magnetite and hematite. Carbon dioxide showed a small influence at 1100°C, and a negligible one at 1250°C. 相似文献
57.
高放废液化学成分分析 总被引:3,自引:0,他引:3
概述了高放废液中25种阳离子、5种阴离子以及总蒸残物、总氧化物、密度和游离酸的分析方法。对核燃料后处理高放废液进行取样分析,其主要化学成分采用两种以上不同原理的方法作对比测定,结果相互符合情况良好,为高放废液处理处置研究设计,提供了完整、准确的基础数据。 相似文献
58.
It has recently been shown that authenticated Byzantine agreement,
in which more than a third of the parties are corrupted, cannot be
securely realized under concurrent or parallel (stateless)
composition. This result puts into question any usage of
authenticated Byzantine agreement in a setting where many
executions take place. In particular, this is true for the whole
body of work of secure multi-party protocols in the case that a
third or more of the parties are corrupted. This is because these
protocols strongly rely on the extensive use of a broadcast
channel, which is in turn realized using authenticated Byzantine
agreement. We remark that it was accepted folklore that the use of
a broadcast channel (or authenticated Byzantine agreement) is
actually essential for achieving meaningful secure multi-party
computation whenever a third or more of the parties are corrupted.
In this paper we show that this folklore is false. We present a
mild relaxation of the definition of secure computation allowing
abort. Our new definition captures all the central security issues
of secure computation, including privacy, correctness and
independence of inputs. However, the novelty of the definition is
in decoupling the issue of agreement from these issues. We
then show that this relaxation suffices for achieving secure
computation in a point-to-point network. That is, we show that
secure multi-party computation for this definition can be achieved
for any number of corrupted parties and without a
broadcast channel (or trusted pre-processing phase as required for
running authenticated Byzantine agreement). Furthermore, this is
achieved by just replacing the broadcast channel in known
protocols with a very simple and efficient echo-broadcast
protocol. An important corollary of our result is the ability to
obtain multi-party protocols that remain secure under composition,
without assuming a broadcast channel. 相似文献
59.
赵惠琴 《有色冶金设计与研究》2004,25(4):4-8
根据所使用的低水泥浇注料的性能,对中铝山西分公司检修厂4号焙烧炉制定了合理的烘烤曲线,提高了耐火内衬的质量,延长了内衬的使用寿命。 相似文献
60.
详细介绍了ZPG系列盘式真空过滤机的主要特点、基本原理和主要技术参数。对盘式真空过滤机的过滤理论进行了系统的研究 ,以及为提高过滤系数和降低滤饼水分所采取的关键措施。与传统的真空过滤机进行了对比 ,表明ZPG系列盘式真空过滤机的滤饼水分可以降低 1 %~ 3 % ,过滤系数提高 3 0 %~5 0 % ,过滤每吨精矿的能耗可以降低 5 0 %左右 ,使得ZPG系列盘式真空过滤机在国内各大冶金矿山得到全面推广使用 ,创造了巨大的经济效益和社会效益。 相似文献