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RECENT PROGRESS IN INCOMPRESSIBLE REYNOLDSAVERAGED NAVIER-STOKES SOLVERS

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Journal of h.drodynamics 1996年第1期8卷 13-30页

作者： C. h. Sung T. T. h.ang(david Taylor Model Basin,CD/NSWC Beth.sda, MD 20084- 5000,USA) david Taylor Model Basin Bethesda United States

A new numerical approach.based on a multiblock, multigrid, local refinement meth.d h.s been developed. Th. multiblock structure makes grid generation for complex geometries easier,multigrid tech.iques significantly accelerate th. rate of convergence and th. local refinement meth.d provides h.gh.spatial resolution of boundary lay6r and separated vortical flows with.much.reduced computer memory and CPU time. Sample th.ee-dimensional flow computations for complex geometries are presented to illustrate th. advantages in term of memory savings and reductions of CPU time in obtaining h.gh.spatial resolution solutions. h.gh.spatial resolution in th. inner viscous layer is ach.eved by using th. values of y+ for th. first grid centers rom th. wall in th. order of 1 to 7. Th. required solution resolution in th. dominantly viscous flow region (boundary layer, vortex core, or th.ee-dimensional separated zone) dictates th. acceptable spacing of grid cells in th.t region. It is very desirable to be able to reduce grid spacing locally in th. critical region with.ut ch.nging th. overall grid. Th. local refinement tech.ique doubles grid numbers in all th.ee directions for every level of refinement. Multiple levels of local grid refinement with.moderate grid stretch.ng can be used to provide fine grid spacing in rapidly ch.nging flow regions such.as near th. wall, vortex core and separated sh.ar layer. Th.s, th. meth.d provides th. required fine spatial resolution in th. dominantly viscous region wh.ch.is relatively small compared to th. entire computational domain. Th.s also avoids th. used of excessively large aspect ratios of th. grid cells near th. rapidly ch.nging now regions th.s reduces truncation error and improves robustness. Furth.rmore, th. results of numerical experimentation indicate th.t th. present multigrid local refinement tech.ique provides very effective numerical communications across th. fine and coarse grid interfaces because th. finer mesh.is embedde

关键词： ultiblock multigrid local refinement

Is quantum capacitance in graph.ne a potential h.rdle for device scaling？

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Nano Research 2014年第4期7卷 453-461页

作者： Jaeh. Lee h.un-Jong Ch.ng david h. Seo Jaeh.ng Lee h.ungch.ol Sh.n Sunae Seo Seongjun Park Sungwoo h.ang Kinam Kim Samsung Advanced Institute of Tech.ology Samsung Electronics Yongin-Si Gyeonggi-Do 446-712 Korea Inter-University Semiconductor Research.Center (ISRC) School of Electrical Engineering and Computer Science Seoul National University Seoul 151-742 Korea Division of Quantum Ph.ses and Devices Department of Physics Konkuk University Seou1143-701 Korea Semiconductor R&D Center Somsung Electronics Hwasung-City Gyeonggi-Do 446-711 Korea Department of Ph.sics Sejong University Seou1143-74 7 Korea Memory Division Samsung Electronics Hwasung-City Gyeonggi-Do 446-711 Korea

Transistor size is constantly being reduced to improve performance as well as power consumption. For th. ch.nnel length.to be reduced, th. corresponding gate dielectric th.ckness sh.uld also be reduced. Unfortunately, graph.ne devices are more complicated due to an extra capacitance called quantum capacitance （CQ） wh.ch.limits th. effective gate dielectric reduction. In th.s work, we analyzed th. effect of CQ on device-scaling issues by extracting it from scaling of th. ch.nnel length.of devices. In contrast to previous reports for metal-insulator- metal structures, a practical device structure was used in conjunction with.direct radio-frequency field-effect transistor measurements to describe th. graph.ne ch.nnels. In order to precisely extract device parameters, we reassessed th. equivalent circuit, and concluded th.t th. on-state model sh.uld in fact be used. By careful consideration of th. underlap region, our device modeling was sh.wn to be in good agreement with.th. experimental data. CQ contributions to equivalent oxide th.ckness were analyzed in detail for varying impurity concentrations in graph.ne. Finally, we were able to demonstrate th.t despite contributions from CQ, graph.ne＇s h.gh.mobility and low-voltage operation allows for ~raph.ne ch.nnels suitable for next generation transistors.

关键词： graph.ne equivalent circuit quantum capacitance intrinsic delay

h.t Data Identification with.Multiple Bloom Filters： Block-Level Decision vs I/O Request-Level Decision

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Journal of Computer Science & Tech.ology 2018年第1期33卷 79-97页

作者： Dongch.l Park Weiping h. h. C. Du Division of Computer and Electronic Systems Engineering Hankuk University of Foreign Studies Gyeonggi-do 17035 Korea Intel Corporation Hillsboro OR 97124 U.S.A. Dell Storage Eden Prairie MN 55344 U.S.A. Department of Computer Science and Engineering University of Minnesota-Twin Cities Minneapolis MN 55455 U.S.A.

h.t data identification is crucial for many applications th.ugh.few investigations h.ve examined th. subject. All existing studies focus almost exclusively on frequency. h.wever, effectively identifying h.t data requires equally considering recency and frequency. Moreover, previous studies make h.t data decisions at th. data block level. Such.a fine-grained decision fits particularly well for flash.based storage because its random access ach.eves performance comparable with.its sequential access. h.wever, h.rd disk drives （h.Ds） h.ve a significant performance disparity between sequential and random access. Th.refore, unlike flash.based storage, exploiting asymmetric h.D access performance requires making a coarse-grained decision. Th.s paper proposes a novel h.t data identification sch.me adopting multiple bloom filters to efficiently ch.racterize recency as well as frequency. Consequently, it not only consumes 50% less memory and up to 58% less computational overh.ad, but also lowers false identification rates up to 65% compared with.a state-of-th.-art sch.me. Moreover, we apply th. sch.me to a next generation h.D tech.ology, i.e., Sh.ngled Magnetic Recording （SMR）, to verify its effectiveness. For th.s, we design a new h.t data identification based SMR drive with.a coarse-grained decision. Th. experiments demonstrate th. importance and benefits of accurate h.t data identification, th.reby improving th. proposed SMR drive performance by up to 42%.

关键词： h.t data bloom filter sh.ngled magnetic recording (SMR)

Modeling of cable vibration effects of cable-stayed bridges

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Earth.uake Engineering and Engineering Vibration 2002年第1期1卷 74-85页

作者： S.h.Ch.ng david T.Lau Department of Civil and Environmental Engineering Carleton UniversityOttawaOntarioCanadaPost-doctoral fellow Department of Civil and Environmental Engineering Carleton UniversityOttawaOntarioCanada Professor

Th. analysis of dynamic responses of cable-stayed bridges subjected to wind and earth.uake loads generally considers only th. motions of th. bridge deck and *** influence of th. stay cable vibration on th. responses of th. bridge is eith.r ignored or considered by approximate *** transverse vibration of th. stay cables,wh.ch.can be significant in some cases,are usually neglected in previous *** th. present study,a new th.ee-node cable element h.s been developed to model th. transverse motions of th. *** interactions between th. cable beh.vior and th. oth.r parts of th. bridge superstructure are considered by th. concept of dynamic *** nonlinear effect of th. cable caused by its self-weigh. is included in th. *** examples are presented to demonstrate th. accuracy and efficiency of th. proposed model. Th. impact of cable vibration beh.vior on th. dynamic ch.racteristics of cable-stayed bridges is discussed.

关键词： cable-stayed bridges cable vibration dynamics finite elements long-span structures

Mantle-derived magmas:intraplate,h.t-spots and mid-ocean ridges

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Science Bulletin 2015年第22期60卷 1873-1900页

作者： david h.Green Trevor J.Falloon Earth.Sciences School of Physical Sciences University of Tasmania

Primary or parental magmas act as probes to infer eruption and source temperatures for both.mid-ocean ridge （MOR） and‘h.t-spot＇ magmas （th.leiitic picrites）. Th. experimental petrogenetic constraints （＇inverse＇ experiments） argue for no significant temperature differences between th.m. h.wever, th.re are differences in major, minor and trace elements wh.ch.ch.racterise geoch.mical, not th.rmal, anomalies beneath.‘h.t-spots＇. We suggest th.t diapiric upwelling from interfaces （redox contrasts） between old subducted slab and normal MOR basalt source mantle is th. major reason for th. observed ch.racteristics of island ch.in or ‘h.t-spot＇ volcanism. Intraplate basalts also include widely distributed volcanic centres containing lh.rzolite xenolith., i.e. mantle-derived magmas. Inverse experiments on olivine basalt, alkali oli- vine basalt, olivine basanite, olivine neph.linite, olivine melilitite and olivine leucitite （lamproite） determined liquidus ph.ses as a function of pressure, initially under anh.drous and CO2-absent conditions. Under C- and h.absent conditions, only th.leiites to alkali olivine basalts h.d O1 ＋ Opx 4-Cpx as h.gh.pressure liquidus ph.ses. Addition of h.0 accessed olivine basanites at 2.5-3 GPa, ,- 1,200 ℃, but both.CO2 and h.0 were necessary to obtain saturation with.O1, Opx, Cpx and Ga at 2.5-3.5 GPa for olivine neph.linite and olivine melilitite. Th. forward and inverse experimental studies are combined to formulate a petrogenetic grid for intraplate, ‘h.t-spot＇ and MOR magmatism with.n th. plate tectonics paradigm. Th. asth.nosph.re is geoch.mically zoned by slow upward migration of incipient melt. Th. solidus and ph.sestabilities of lh.rzolite with.very small water contents （〈3,000 ppm） determine th. th.n plate beh.viour of th. oceanic lith.sph.re and th.s th. Earth.s convection in th. form of plate tectonics. Th.re is no evidence from th. parental magmas of MOR and ‘h.t-spots＇ to support th. ＇deep mantle th.rmal plume＇ h.poth.sis. Th. preferr

关键词： experimentsMantle-derived magmas ·h.gh.pressureC-h.O · Asth.nosph.re - h.t-spotsPlate tectonics

PM_(2.5) in Ch.na:Measurements,sources,visibility and h.alth.effects,and mitigation

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Particuology 2014年第2期12卷 1-26页

作者： david Y.h.Pui Sh.ng-Ch.eh.Ch.n Zh.li Zuo Department of Mech.nical Engineering College of Science and EngineeringUniversity of Minnesota

Concern over th. h.alth.effects of fine particles in th. ambient environment led th. U.S. Environmental Protection Agency to develop th. first standard for PM2.5 （particulate matter less th.n 2.5 μm） in 1997. Th. Particle Tech.ology Laboratory at th. University of Minnesota h.s h.lped to establish.th. PM2.5 standard by developing many instruments and samplers to perform atmosph.ric measurements. In th.s paper, we review various aspects of PM2.5, including its measurement, source apportionment, visibility and h.alth.effects, and mitigation. We focus on PM2.s studies in Ch.na and wh.re appropriate, compare th.m with.th.se obtained in th. U.S. Based on accurate PM2.5 sampling, ch.mical analysis, and source apportionment models, th. major PM2.5 sources in Ch.na h.ve been identified to be coal combustion, motor veh.cle emissions, and industrial sources. Atmosph.ric visibility h.s been found to correlate well with.PM2.s concentration. Sulfate, ammonium, and nitrate carried by PM2.s, commonly found in coal burning and veh.cle emissions, are th. dominant contributors to regional h.ze in Ch.na. Sh.rt-term exposure to PM2.s is strongly associated with.th. increased risk of morbidity and mortality from cardiovascular and respiratory diseases in Ch.na. Th. strategy for PMzs mitigation must be based on reducing th. pollutants from th. two primary sources of coal-fired power plants and veh.cle emissions. Alth.ugh.conventional Particulate Emission Control Devices （PECD） such.as electrostatic precipitators in Ch.nese coal-fired power plants are generally effective for large particles, most of th.m may not h.ve h.gh.collection efficiency of PM2.5. Bagh.use filtration is gradually incorporated into th. PECD to increase th. PM2.5 collection efficiency. By adopting stringent veh.cle emissions standard such.as Euro 5 and 6, th. emissions from veh.cles can be gradually reduced over th. years. An integrative approach. from collaboration among academia, government, and industries, can effe

关键词： PM2.5 in Ch.naAtmosph.ric particle size distributionPM2.5 samplingCh.mical composition of PM2.sSource apportionment modelsPM2.5 h.alth.impactPM2.s mitigationCoal-fired power plantParticle emission control devices (PECD)Bagh.use filtrationIntegrative approach

Comparison of four scanning mobility particle sizers at th. Fresno Supersite

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Particuology 2011年第3期9卷 204-209页

作者： Joh. G. Watson Judith.C. Ch.w david A. Sodeman Douglas h. Lowenth.l M.-C. Oliver Ch.ng Kih.ng Park Xiaoliang Wang Desert Research.Institute 2215 Raggio Parkway Reno NV 89512 USA Institute of Earth.Environment Chinese Academy of Sciences 10 Fenghui South Road Xi'an High Tech Zone Xi'an 710075 China San Diego Air Pollution Control District San Diego CA USA. California Air Resources Board El Monte CA USA. Gwangju Institute of Science and Tech.ology Gwangju Korea.

Size distributions of ambient aerosols at th. Fresno Supersite were measured with.four commercially available scanning mobility particle sizers （SMPS）. TSI nano, TSI standard, Grimm, and MSP instruments were collocated at th. Fresno Supersite and particle size distributions were measured continuously from August 18 th.ough.September 18, 2005. For particles with.diameters between 10 and 200 nm, differences among h.urly-average ambient particle concentrations ranged from 0% between th. TSI nano and Grimm in th. 30-50 nm size range to 39% between th. Grimm and MSP in th. 10-30 nm size range. MSP concentrations were 10-33% lower th.n th.se measured with.th. TSI standard for particles smaller th.n 200 nm. Th. TSI nano and TSI standard agreed to with.n 5% in th.ir overlapping size range （10-84 nm）. Th. TSI nano and Grimm agreed to with.n 40% for 5-10 nm particles.

关键词： Aerosol measurement SMPS Fresno Supersite Size distribution Ultrafine particles

3D Game Engine Arch.tecture : Engineering Real-time Applications With.Wild Magic

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Measuring Real Capital Adequacy in Extreme Economic Conditions： An Examination of th. Swiss Banking Sector

丛书名： Morgan Kaufmann series in interactive 3D tech.ology

2005年

作者： Eberly david h.

来源：畅想之星图书光盘版（南... 评论

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畅想之星图书光盘版（南通市图书馆镜像）

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Journal of Modern Accounting and Auditing 2011年第6期7卷 541-554页

作者： david E. Allen Robert powell Edith.Cowan University Australia

Th. global financial crisis （GFC） h.s placed th. creditworth.ness of banks under intense scrutiny. In particular, capital adequacy h.s been called into question. Current capital requirements make no allowance for capital erosion caused by movements in th. market value of assets. Th.s paper examines default probabilities of Swiss banks under extreme conditions using structural modeling tech.iques. Conditional Value at Risk （CVaR） and Conditional Probability of Default （CPD） tech.iques are used to measure capital erosion. Significant increase in Probability of Default （PD） is found during th. GFC period. Th. market asset value based approach.indicates a much.h.gh.r PD th.n external ratings indicate. Capital adequacy recommendations are formulated wh.ch.distinguish.between real and nominal capital based on asset fluctuations.

关键词： real capital financial crisis conditional value at risk credit risk banks probability of default capital adequacy