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Search Results: 1 - 10 of 78242 matches for " Darui Chen "
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Sustainable Throughput of Wireless LANs with Multi-Packet Reception Capability under Bounded Delay-Moment Requirements
Ying Jun,Zhang,Soung Chang Liew,Darui Chen
Computer Science , 2010,
Abstract: With the rapid proliferation of broadband wireless services, it is of paramount importance to understand how fast data can be sent through a wireless local area network (WLAN). Thanks to a large body of research following the seminal work of Bianchi, WLAN throughput under saturated traffic condition has been well understood. By contrast, prior investigations on throughput performance under unsaturated traffic condition was largely based on phenomenological observations, which lead to a common misconception that WLAN can support a traffic load as high as saturation throughput, if not higher, under non-saturation condition. In this paper, we show through rigorous analysis that this misconception may result in unacceptable quality of service: mean packet delay and delay jitter may approach infinity even when the traffic load is far below the saturation throughput. Hence, saturation throughput is not a sound measure of WLAN capacity under non-saturation condition. To bridge the gap, we define safe-bounded-mean-delay (SBMD) throughput and safe-bounded-delay-jitter (SBDJ) throughput that reflect the actual network capacity users can enjoy when they require finite mean delay and delay jitter, respectively. Our earlier work proved that in a WLAN with multi-packet reception (MPR) capability, saturation throughput scales super-linearly with the MPR capability of the network. This paper extends the investigation to the non-saturation case and shows that super-linear scaling also holds for SBMD and SBDJ throughputs. Our results here complete the demonstration of MPR as a powerful capacity-enhancement technique for WLAN under both saturation and non-saturation conditions.
Delay Analysis for Wireless Local Area Networks with Multipacket Reception under Finite Load
Ying Jun Zhang,Soung Chang Liew,Darui Chen
Computer Science , 2008,
Abstract: To date, most analysis of WLANs has been focused on their operation under saturation condition. This work is an attempt to understand the fundamental performance of WLANs under unsaturated condition. In particular, we are interested in the delay performance when collisions of packets are resolved by an exponential backoff mechanism. Using a multiple-vacation queueing model, we derive an explicit expression for packet delay distribution, from which necessary conditions for finite mean delay and delay jitter are established. It is found that under some circumstances, mean delay and delay jitter may approach infinity even when the traffic load is way below the saturation throughput. Saturation throughput is therefore not a sound measure of WLAN capacity when the underlying applications are delay sensitive. To bridge the gap, we define safe-bounded-mean-delay (SBMD) throughput and safe-bounded-delay-jitter (SBDJ) throughput that reflect the actual network capacity users can enjoy when they require bounded mean delay and delay jitter, respectively. The analytical model in this paper is general enough to cover both single-packet reception (SPR) and multi-packet reception (MPR) WLANs, as well as carrier-sensing and non-carrier-sensing networks. We show that the SBMD and SBDJ throughputs scale super-linearly with the MPR capability of a network. Together with our earlier work that proves super-linear throughput scaling under saturation condition, our results here complete the demonstration of MPR as a powerful capacity-enhancement technique for both delay-sensitive and delay-tolerant applications.
Influences of marine floor hydrothermal activity on organic matter abundance in marine carbonate rocks — A case study of middle-upper Proterozoic in the northern part of North China
Jie Wang,Jianfa Chen,Zhidong Bao,Shuichang Zhang,Yongchang Xu,Darui Wang
Chinese Science Bulletin , 2006, DOI: 10.1007/s11434-006-0585-7
Abstract: Study indicates that the elements rich in marine floor hydrothermal fluids have a positive influence, not only on total organic carbon (TOC), but also on the abundance of SiO2 in some Middle-Upper Proterozoic strata. The TOC bears a better positive correlation with abundance of SiO2. By the correlation analysis between organic matter and sea-floor hot fluid characterized trace elements such as P, Cu, Zn, Ni, Ba, etc in marine carbonate rocks, we conclude that organic matter enrichment of carbonate rocks were related to marine floor hydrothermal activity in a part of layers. Some thin-layered cherts, which were thought to be the indicators of hydrothermal activity, frequently occurring in Gaoyuzhuang, Wumishan, Tieling and Xiamaling formation support our conclusion. With the increasing of trace elements in marine carbonate rocks, the TOC and Fe/Ti ratio is creasing. In contrast, the Al/(Al+Fe+Mn) ratio is usually decreasing.
Effects of UV/Ag-TiO2/O3 advanced oxidation on unicellular green alga Dunaliella salina: Implications for removal of invasive species from ballast water

Donghai Wu,Hong You,Jiaxuan Du,Chuan Chen,Darui Jin,

环境科学学报(英文版) , 2011,
Abstract: The UV/Ag-TiO2/O3 process was investigated for ballast water treatment using Dunaliella salina as an indicator. Inactivation curves were obtained, and the toxicity of e uent was determined. Compared with individual unit processes using ozone or UV/Ag-TiO2, the inactivation e ciency of D. salina by the combined UV/Ag-TiO2/O3 process was enhanced. The presence of ozone caused an immediate decrease in chlorophyll a (chl-a) concentration. Inactivation e ciency and chl-a removal e ciency were positively correlated with ozone dose and ultraviolet intensity. The initial total residual oxidant (TRO) concentration of e uent increased with increasing ozone dose, and persistence of TRO resulted in an extended period of toxicity. The results suggest that UV/Ag-TiO2/O3 has potential for ballast water treatment.
Developmental modes of the Neoproterozoic-Lower Paleozoic marine hydrocarbon source rocks in China
BaoMin Zhang,ShuiChang Zhang,LiZeng Bian,ZhiJun Jin,DaRui Wang
Chinese Science Bulletin , 2007, DOI: 10.1007/s11434-007-6018-4
Abstract: Based on the researches on rock type, the mode of occurrence, diagnostic minerals and creatures, the sedimentary geochemistry and organic facies of Chinese marine source rocks from wells and outcrops, and on the research findings of developmental modes of foreign marine source rock, the authors consider that it is impossible to objectively make clear the formation mechanism of hydrocarbon source rock with high organic matter abundance by either single mode of preservation or high organic matter productivity. According to the Chinese geological features, the formation mechanism of the Neoproterozoic-Lower Paleozoic marine source rock is generalized into four modes, namely, thermal water activity-upwelling flow-anoxic; carbonate gentle slope-upwelling flow; xerothermic climate-brine euxinic milieu; and humid climate-retained euxinic milieu; as the Lower Cambrian undercompensation basin organic facies (the Tarim Basin, South China and southwestern margin of North China), carbonate gentle lime mud bound organic facies (the Upper Ordovician in Tazhong region of the Tarim Basin and the Lower Silurian in the Upper Yangtze Platform), the Middle Cambrian evaporation laggon organic facies (the Tarim Basin and the Upper Yangtze Platform), enclosed undercompensation terrigenous bay organic facies (the Middle-Upper Ordovician in the west of the Tarim Basin, the Lower Silurian Long-maxi Formation in the Upper Yangtze platform). Chinese marine sedimentations with lower organic matter abundance are generalized into two modes of consumption-dilution mode of open epicontinental sea and depletion-dilution mode of supercompensation basin.
A model for carbon isotope distribution of methane during diagenesis
Ping Guan,Yongchang Xu,Wenhui Liu,Darui Wang
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02883643
Abstract: The evolution of methane carbon isotope with depth has been discussed based on diagenetic reaction kinetics and isotopic Rayleigh fractionational theory. A mathematical model to describe data of methane carbon isotope for the Liaohe oil field has been established.
A model for carbon isotope distribution of methane duringdiagenesis

Ping Guan,Yongchang Xu,Wenhui Liu,Darui Wang,

科学通报(英文版) , 1998,
Abstract: The evolution of methane carbon isotope with depth has been discussed based on diagenetic reaction kinetics and isotopic Rayleigh fractionational theory. A mathematical model to describe data of methane carbon isotope for the Liaohe oil field has been established.
Analysis on Characteristics of Citation of Petroleum Exploration and Development
《石油勘探与开发》论文被引分析

WANG DaRui,GUO HaiLi,MIAO Xin,
王大锐
,郭海莉,缪昕

中国科技期刊研究 , 2006,
Abstract: 根据近年“中国科技期刊引证报告”(CJCR)的统计数据,从影响因子和总被引频次两个指标对《石油勘探与开发》刊出的论文近年的引证情况进行了统计和分析、评议,提出了科技期刊要“贴近科研、贴近生产、服务科研、服务生产”的办刊理念,来源于科研、生产第一线的高质量稿源是期刊保持高水平的根本因素。
Analysis on Chinese Oil and Gas Journals Cited by American Petroleum Abstracts (PA)
美国《石油文摘》收录中国油气类期刊情况分析

WANG DaRui,SONG LiChen,
王大锐
,宋立臣

中国科技期刊研究 , 2008,
Abstract: 介绍了美国《石油文摘》数据库收录中国大陆油气类期刊的基本情况,以及所提供的主要服务。认为中国油气类期刊应该在国际期刊数据库中占有更大的比例,努力提高期刊的学术水平与影响力,提高英文摘要的信息量,坚持沟通提高期刊的自身显示度是进入国际著名检索数据库的重要前提。
Analysis on Characteristics of Illustrations Printed in Famous Chinese and Foreign Oil and Gas Journals and Its Inspiration
国内外著名油气期刊插图特色分析与启迪

WANG DaRui,FU GaiRong,LI XiuXian,
王大锐
,付改荣,李秀贤

中国科技期刊研究 , 2007,
Abstract: 分析研究了国内外12种著名而优秀的油气类科技期刊的插图风格与特色,包括插图的比重,图幅的尺寸,色彩的使用,及其他多种表达特色。发现国外期刊中图件基本不受版面的限制,而国内期刊中的图件则严格受版面限制的规律性特点,认为国外期刊的做法是应该学习借鉴的。
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