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Numerical investigation of pyrolysis effects on heat transfer characteristics and flow resistance of n-decane under supercritical pressure

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Chinese Journal of Aeronautics 2018年第6期31卷 1249-1257页

作者： Zhi TAO Xizhuo HU Jianqin ZHU Hongwei wu National Key Laboratory of Science and Technology on Aero-thermodynamies School of Energy and Power EngineeringBeihang University Beijing 100083 China School of Engineering and Technology University of Hertfordshire Hatfield AL10 9AB United Kingdom

Pyrolysis of hydrocarbon fuel plays an important role in the regenerative cooling process. In this article, a Two-Dimensional（2D） numerical model is proposed to investigate the pyrolysis effects on the heat transfer characteristics and flow resistance of n-decane under supercritical pressure. The one-step global pyrolytic reaction mechanism consisting of 19 species is adopted to simulate the pyrolysis process of n-decane. The thermophysical and transport properties of the fluid mixture are computed and incorporated into the numerical model for simulation. Comparisons between the current predictions and the open published experimental data are carried out and good agreement is achieved. In order to better understand the complicated physicochemical process, further investigations on the turbulent flow and heat transfer coupled with pyrolysis in a tube have been performed under various operating conditions. The results indicate that the pyrolysis intensively takes place in the high fluid temperature region. The occurrence of the heat transfer deterioration would lead to increasing n-decane conversion at the beginning of the heated section. It is found that the pyrolysis could improve the heat transfer deterioration and promote the heat transfer enhancement. Meanwhile, pyrolysis gives rise to an abrupt increase of flow resistance. The mechanisms of the physicochemical phenomena are also analyzed in a systematic manner, which would be very helpful in the development of the regenerative cooling technology.

关键词： n-Decane Convective heat transfer Flow resistance Pyrolysis Supercritical pressure

Rethinking the architecture design of data center networks

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Frontiers of Computer Science 2012年第5期6卷 596-603页

作者： Kaishun wu Jiang XIAO Lionel M. NI National Engineering Research Center of Digital Life State-Province Joint Laboratory of Digital Home Interactive Applications School of Physics and Engineering Sun Yat-sen University Guangzhou 510006 China Department of Computer Science and Engineering Hong Kong University of Science and Technology Hong Kong China

In the rising tide of the Internet of things, more and more things in the world are connected to the Internet. Recently, data have kept growing at a rate more than four times of that expected in Moore＇s law. This explosion of data comes from various sources such as mobile phones, video cameras and sensor networks, which often present multidi- mensional characteristics. The huge amount of data brings many challenges on the management, transportation, and pro- cessing IT infrastructures. To address these challenges, the state-of-art large scale data center networks have begun to provide cloud services that are increasingly prevalent. How- ever, how to build a good data center remains an open chal- lenge. Concurrently, the architecture design, which signifi- cantly affects the total performance, is of great research inter- est. This paper surveys advances in data center network de- sign. In this paper we first introduce the upcoming trends in the data center industry. Then we review some popular design principles for today＇s data center network architectures. In the third part, we present some up-to-date data center frame- works and make a comprehensive comparison of them. Dur- ing the comparison, we observe that there is no so-called op- timal data center and the design should be different referring to the data placement, replication, processing, and query pro- cessing. After that, several existing challenges and limitations are discussed. According to these observations, we point out some possible future research directions.

关键词： data center networks switch-based networks,direct networks hybrid networks

Simulations of Coarsening Behavior for M_(23)C_6 Carbides in AISI H13 Steel

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Journal of Materials Science & Technology 2006年第2期22卷 153-158页

作者： Xinbin HU Mei ZHANG Xiaochun wu Lin LI School of Materials Science and Engineering Shanghai University Shanghai 200072 China School of Mechanical Engineering Hubei University of Technology Wuhan 430068 China

Based on the local equilibrium assumption, coarsening behavior of M23C6 carbide at 700℃ in H13 steel was simulated by DICTRA software. The results from the calculations were compared with transmission electron microscopy （TEM） observations. The results show the interracial energy for M23C6 in H13 steel at 700℃ is thus probably 0.7J·m^-2, which fits the experiments well. The influence of composition and temperature on the coarsening rate was also investigated by simulations. Simulations show a decrease in the coarsening rate when V/Mo ratio is increased, while the coarsening rate increases with increasing temperature.

关键词： DICTRA Simulation Carbides coarsening AISI H13 steel Interfacial energy

Ultradeep diamonds originate from deep subducted sedimentary carbonates

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Science China Earth Sciences 2017年第2期60卷 207-217页

作者： GAO Jing NIU JingJing QIN Shan wu Xiang Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of EducationSchool of Earth and Space SciencesPeking University State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences

Diamonds are renowned as the record of Earth's evolution *** diamonds on the Earth can be distinguished in light of genetic types as kimberlitic diamonds(including peridotitic diamonds and eclogitic diamonds),ultrahigh-pressure metamorphic diamonds and ophiolitic *** to the inclusion mineralogy,most diamonds originated from continental lithospheric mantle at depths of 140-250 *** localities,however,yield ultradeep diamonds with inclusion compositions that require a sublithospheric origin(>~250 km).Ultradeep diamonds exhibit distinctions in terms of carbon isotope composition,N-concentration,mineral inclusions and so *** present study provides a systematic compilation concerning the features of ultradeep diamonds,based on which to expound their genesis affinity with mantle-carbonate *** diamond-parental carbonate melts are proposed to be stemmed from the Earth's crust through subduction of oceanic *** diamonds are classified into a subgroup attaching to kimberlitic diamonds grounded by formation mechanism,and present connections in respect of carbon origin to eclogitic diamonds,ultrahigh-pressure metamorphic diamonds and ophiolitic diamonds.

关键词： Ultradeep diamond Carbonates Oceanic subduction Earth carbon cycle

A polyoxometalate-functionalized two-dimensional titanium carbide composite MXene for effective cancer theranostics

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Nano Research 2018年第8期11卷 4149-4168页

作者： Luyan Zong Huixia wu Han Lin Yu Chen The Key Laboratory of Resource Chemistry of Ministry of Education Shanghai Key Laboratory of the Rare Earth Functional Materialsand Shanghai Municipal Education Committee Key Laboratory of Molecular Imaging Probes and Sensors Shanghai NormalUniversity Shanghai 200234 China State Key Laboratory of High Performance Ceramics and Superfine Microstructures Shanghai Institute of Ceramics ChineseAcademy of Sciences Shanghai200050 China

As a new family of two-dimensional （2D） nanomaterials, MXenes have recently attracted much attention because of high performance in versatile applications including energy storage and electrochemistry, but their specific application to biomedicine has been rarely reported, especially for theranostic nanomedicine, i.e., concurrent diagnostic imaging and therapy. This study shows for the first time surface engineering and functionalization of 2D Ti3C2 MXene nanosheets by the integration of GdWl0-based polyoxometalates （POMs）. These multifunctional GdWlo@Ti3C2 composite nanosheets provide hypertherrnal treatment with magnetic resonance （MR） and/or computed tomography （CT） imaging guidance toward tumor cells or xenografts. A tumor was effectively eradicated without further reoccurrence during the observation period. GdW10 nanoclusters that were integrated onto the surface of Ti3C2 nanosheets were demonstrated to serve as a contrast agent for contrast-enhanced CT and MR imaging based on their unique composition, thus showing the potential for diagnostic-imaging guidance and monitoring for tumor hyperthermia nanotherapy. The high in vivo biocompatibility of GdW10@TiaC2 composite nanosheets was demonstrated to guarantee their subsequent translation into a medical treatment. This study provides a novel strategy for broadening the biomedical applications of MXenes by surface engineering and multifunctionalization, which is expected to promote further exploration of biomedical applications of MXenes in nanotheranostics.

关键词： titanium carbide MXene,polyoxometalate dual-mode imaging photothermal therapy

Lateral dynamic flight stability of hovering insects: theory vs. numerical simulation

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Acta Mechanica Sinica 2012年第1期28卷 221-231页

作者： Yan-Lai Zhang Jiang-Hao wu Mao Sun Ministry-of-Education Key Laboratory of Fluid Mechanics Beihang University100191 BeijingChina

In the present paper, the lateral dynamic flight stability properties of two hovering model insects are predicted by an approximate theory based on the averaged model, and computed by numerical simulation that solves the complete equations of motion coupled with the Naviertokes equations. Comparison between the theoretical and simulational results provides a test to the validity of the assumptions made in the theory. One of the insects is a model dronefly which has relatively high wingbeat frequency （164Hz） and the other is a model hawkmoth which has relatively low wingbeat frequency （26 Hz）. The following conclusion has been drawn. The theory based on the averaged model works well for the lateral motion of the dronefly. For the hawkmoth, relatively large quantitative differences exist between theory and simulation. This is because the lateral non-dimensional eigenvalues of the hawkmoth are not very small compared with the non-dimensional flapping frequency （the largest lateral non-dimensional eigenvalue is only about 10% smaller than the non-dimensional flapping frequency）. Nevertheless, the theory can still correctly predict variational trends of the dynamic properties of the hawkmoth＇s lateral motion.

关键词： Insect - Hovering Lateral dynamic flight stabil- ity Averaged model Equations-of-motion Navier-Stokes simulation

Historical trends of heavy metal contamination and their sources in lacustrine sediment from Xijiu Lake,Taihu Lake Catchment,China

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Journal of Environmental Sciences 2011年第10期23卷 1671-1678页

作者： Haijian Bing Yanhong wu Zhaobin Sun Shuchun Yao Nanjing Institute of Geography and Limnology Chinese Academy of Sciences State Key Laboratory of Lake Science and Environment Nanjing 210008 China Graduate University of the Chinese Academy of Science Beijing 100049 China Institute of Mountain Hazard and Environment Chinese Academy of Sciences Chengdu 610041 China

Concentrations of Cd, Cr, Cu, Pb, Zn and Hg in Xijiu Lake sediment from the Taihu Lake catchment, China, were analyzed. Their contamination state was investigated based on the geoaccumulation index and enrichment factors. Statistical analysis was used to differentiate the anthropogenic versus natural sources of heavy metals （HMs）, and the anthropogenic accumulation fluxes were calculated to quantify anthropogenic contribution to HMs. The results indicated that the lake sediment had been heavily contaminated by Cd, enrichment of Zn and Hg was at a relatively high level, while that of Cu and Pb was in the lower-to-moderate level and Cr was in the low enrichment level. Sources of Cr in the sediment were mainly from natural inputs, while other metals, especially Cd, were predominantly derived from anthropogenic sources. In the past century, anthropogenic accumulation fluxes of Pb, Zn and Hg increased by 0.147.3 mg/（cm2-yr）, 2.4-398.1 mg/（***）, and 3.7-110.3 ng/（***）, respectively, accounting for most inputs of HMs entering the sediment. The contamination state of HMs varied with industrial development of the catchment, which demonstrated that contamination started in the early 20th century, reached the maximal level between the mid-1970s and mid-1990s, and decreased a little after the implementation of constraints on high contamination industries, although the contamination of some HMs, such as Cd, Zn and Hg, is still at high levels.

关键词： accumulation fluxes contamination heavy metals human activity sediment Xijiu Lake

Dynamic programming methodology for multi-criteria group decision-making under ordinal preferences

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Journal of Systems Engineering and Electronics 2010年第6期21卷 975-980页

作者： wu Li Guanqi Guo Chaoyuan Yue Yong Zhao School of Information and Communication Engineering Hunan Institute of Science and Technology Yueyang 414006 E R. China Institute of Systems Engineering Huazhong University of Science and Technology Wuhan 430074 P. R. China

A method of minimizing rankings inconsistency is proposed for a decision-making problem with rankings of alternatives given by multiple decision makers according to multiple criteria. For each criteria, at first, the total inconsistency between the rankings of all alternatives for the group and the ones for every decision maker is defined after the decision maker weights in respect to the criteria are considered. Similarly, the total inconsistency between their final rankings for the group and the ones under every criteria is determined after the criteria weights are taken into account. Then two nonlinear integer programming models minimizing respectively the two total inconsistencies above are developed and then transformed to two dynamic programming models to obtain separately the rankings of all alternatives for the group with respect to each criteria and their final rankings. A supplier selection case illustrated the proposed method, and some discussions on the results verified its effectiveness. This work develops a new measurement of ordinal preferences’ inconsistency in multi-criteria group decision-making （MCGDM） and extends the cook-seiford social selection function to MCGDM considering weights of criteria and decision makers and can obtain unique ranking result.

关键词： multi-criteria group decision-making (MCGDM) ordinal preference minimum deviation method dynamic programming Cook-Seiford social selection function.

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Bio-network medicine

Journal of Molecular Cell Biology 2015年第3期7卷 185-186页

作者： Luonan Chen Jiarui wu Key Laboratory of Systems Biology Innovation Center for Cell Signaling NetworkInstitute of Biochemistry and Cell BiologyShanghai Institutes for Biological SciencesChinese Academy of SciencesShanghai 200031China Key Laboratory of Systems Biology Institute of Biochemistry and Cell BiologyShanghai Institutes for Biological SciencesChinese Academy of SciencesShanghai 200031China

Complex diseases such as cancer or diabetes generally not result from mutations or malfunctions of individual molecules but from dysfunction of relevant ***,it is of great importance to analyze molecular mechanisms of... 详细信息

关键词： diseases networks. network