检索结果-南通市图书馆

Gas kinetic algorithm for flows in Poiseuille-like microchannels using Boltzmann model equation

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2005年第4期48卷 496-512页

作者： LI Zhihui1,2, ZHAnG Hanxin1 & FU Song2 ⒈ national laboratory for CFD, Hypervelocity Aerodynamics Institute,China Aerodynamics research and Development Center,Mianyang 621000,China 2.department of Engineering Mechanics,Tsinghua University,Beijing 100084,China national laboratory for CFD Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development Center Mianyang China department of Engineering Mechanics Tsinghua University Beijing China

The gas-kinetic unified algorithm using Boltzmann model equation have been extended and developed to solve the micro-scale gas flows in Poiseuille-like micro-channels from Micro-Electro-Mechanical Systems (MEMS). The numerical modeling of the gas kinetic boundary conditions suitable for micro-scale gas flows is presented. To test the present method, the classical Couette flows with various Knudsen numbers, the gas flows from short microchannels like plane Poiseuille and the pressure-driven gas flows in two-dimensional short microchannels have been simulated and compared with the approximate solutions of the Boltzmann equation, the related DSMC results, the modified n-S solutions with slip-flow boundary theory, the gas-kinetic BGK-Burnett solutions and the experimental data. The comparisons show that the present gas-kinetic numerical algorithm using the mesoscopic Boltzmann simplified velocity distribution function equation can effectively simulate and reveal the gas flows in microchannels. The numerical experience indicates that this method may be a powerful tool in the numerical simulation of micro-scale gas flows from MEMS.

关键词： Boltzmann model equation, discrete velocity ordinate method, finite-difference scheme, Couette flow, Poiseuille flow, gas flow in short-microchannel.

Fast and Accurate Predictor-Corrector Methods Using Feedback-Accelerated Picard Iteration for Strongly nonlinear Problems

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2024年第5期139卷 1263-1294页

作者： Xuechuan Wang Wei He Haoyang Feng Satya n.Atluri School of Astronautics Northwestern Polytechnical UniversityXi’an710072China department of Mechanical Engineering Texas Tech UniversityLubbock79409USA

Although predictor-corrector methods have been extensively applied,they might not meet the requirements of practical applications and engineering tasks,particularly when high accuracy and efficiency are necessary.A novel class of correctors based on feedback-accelerated Picard iteration(FAPI)is proposed to further enhance computational *** optimal feedback terms that do not require inversion of matrices,significantly faster convergence speed and higher numerical accuracy are achieved by these correctors compared with their counterparts;however,the computational complexities are comparably *** advantages enable nonlinear engineering problems to be solved quickly and accurately,even with rough initial guesses from elementary *** proposed method offers flexibility,enabling the use of the generated correctors for either bulk processing of collocation nodes in a domain or successive corrections of a single node in a finite difference *** our method,the functional formulas of FAPI are discretized into numerical forms using the collocation *** collocated iteration formulas can directly solve nonlinear problems,but they may require significant computational resources because of the manipulation of *** address this,the collocated iteration formulas are further converted into finite difference forms,enabling the design of lightweight predictor-corrector algorithms for real-time *** generality of the proposed method is illustrated by deriving new correctors for three commonly employed finite-difference approaches:the modified Euler approach,the Adams-Bashforth-Moulton approach,and the implicit Runge-Kutta ***,the updated approaches are tested in solving strongly nonlinear problems,including the Matthieu equation,the Duffing equation,and the low-earth-orbit tracking *** numerical findings confirm the computational accuracy and efficiency of the derived predictor-correc

关键词： Predictor-corrector method feedback-accelerated Picard iteration nonlinear dynamical system real-time computation

Developmental impacts and toxicological hallmarks of silver nanoparticles across diverse biological models

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Environmental Science and Ecotechnology 2024年第3期19卷 60-79页

作者： Yán Wāng Yapeng Han De-Xiang Xu department of Toxicology School of Public Health&Key Laboratory of Environmental Toxicology of Anhui Higher Education InstitutesAnhui Medical UniversityHefei230032China

Silver nanoparticles(AgnPs),revered for their antimicrobial prowess,have become ubiquitous in a range of products,from biomedical equipment to food ***,amidst their rising popularity,concerns loom over their possible detrimental effects on fetal development and subsequent adult *** review delves into the developmental toxicity of AgnPs across diverse models,from aquatic species like zebrafish and catfish to mammalian rodents and in vitro embryonic stem *** focus encompasses the fate of AgnPs in different contexts,elucidating associated hazardous results such as embryotoxicity and adverse pregnancy ***,we scrutinize the enduring adverse impacts on offspring,spanning impaired neurobehavior function,reproductive disorders,cardiopulmonary lesions,and *** hallmarks of developmental harm are identified,encompassing redox imbalances,inflammatory cascades,DnA damage,and mitochondrial ***,we explore potential explanations,linking immunoregulatory dysfunction and disrupted epigenetic modifications to AgnPsinduced developmental *** substantial progress,our understanding of the developmental risks posed by AgnPs remains incomplete,underscoring the urgency of further research in this critical area.

关键词： Silver nanoparticles(AgnPs) Developmental toxicity Maternal exposure Fetal development Redox imbalance Mitochondrial dysfunction

EFFECTS OF SUBMERGED MACROPHYTES On SEDIMEnT SUSPEnSIOn AnD nH_4-n RELEASE UnDER HYDRODYnAMIC COnDITIOnS

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2010年第6期22卷 810-815页

作者： WAnG Chao WAnG Cun WAnG Ze Key laboratory of Integrated Regulation and Resource department on Shallow Lakes Ministry of EducationHohai University Nanjing 210098 China State Key laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing210098 China College of Mechanics and materials Hohai University Nanjing 210098 China

Aquatic vegetation affects sediment suspension and nutrient release by changing the flow structure. Experiments on the influence of submerged vegetation on flow structure, sediment suspension, and nH4-n release were carried in a flume with natural submerged vegetation. Turbulence characteristics in the vegetation section were measured using a three-dimensional acoustic Doppler velocimeter. The effects of submerged vegetation on bed shear stress （ τb ）, sediment suspension, and nH4-n release were analyzed. Results show that with vegetation, bed shear stress is reduced by about 20% - 80%, which, in turn, reduces sediment suspension. The impact of submerged vegetation on sediment suspension and nH4-n release should be considered along with flow intensity. When the flow Reynolds number is relatively small, the submerged vegetation is quite capable of inhibiting sediment suspension and reducing nH4-n release, but when the Reynolds number reaches a certain value, the presence of aquatic plants exacerbates sediment suspension and promotes nH4-n release. Results also reveal that a highly significant positive correlation exists between nH4-n concentration and water turbidity in both vegetated and non-vegetated channels.

关键词： sediment suspension submerged macrophytes turbulence behavior bed shear stress turbidity

Sequencing of phosphopeptides sulfonated by 4-sulfophenyl isothiocyanate using post-source decay matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

在线全文

学校读者我要写书评

暂无评论

Progress in natural Science:materials International 2006年第9期16卷 930-935页

作者： TAnG Jianguang , WAnG Yongjun , ZHAnG Hainan, WAnG Chunyu, HU Zhiping, XUE Zhigang, XIA Kun3 and SHI Xiaoliu ( department of neurology, the Second Xiangya Hospital, Central South University, Changsha 410011, China department of Digestion, the Second Xiangya Hospital, Central South University, Changsha 410011, China national Key laboratory of Chinese Genetics, Changsha 410078, China) department of neurology The Second Xiangya Hospital Central South University Changsha 410011 China department of Digestion The Second Xiangya Hospital Central South University Changsha 410011 China national Key laboratory of Chinese Genetics Changsha 410078 China

Phosphorylation/dephosphorylation is probably the most common and important reversible post-translational modification of proteins. Analyzing the functional effects of phosphorylation is helpful for understanding the biological functions of proteins. Identification of the phosphorylation sites of phosphorylated protein is a prerequisite for research on phosphorylation. In this work, an effective and simple method of identification of protein phosphorylation sites has been developed. Phosphopeptides were selectively enriched with immobilized metal affinity chromatography (IMAC) and subsequently chemically modified by 4-sulfophenyI isothiocyanate, and then the chemically modified phosphopeptides were sequenced with post-source decay (PSD) matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry for detecting phosphorylation sites. The charge of derivatization by 4-sulfophenyl isothiocyanate introduces a negative sulfonic acid group at the n-terminus of a peptide, and enables the selective detection of only a single series of C-terminal y-type ions. This chemically assisted method greatly simplifies the extremely complex pattern of PSD fragment ions and makes the PSD spectra more easier to be interpreted. The phosphorylation sites of a synthesized model phosphopeptide and human c-myc protein have been successfully identified by this method.

关键词： phosphopeptides sequencing 4-sulfophenyl isothiocyanate post-source decay matrix-assisted laser desorption/ion-ization time-of-flight mass spectrometry.

A method for exploring some new solutions of complex lamellar flow

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Communications in nonlinear Science and numerical Simulation 2000年第1期5卷 17-20页

作者： Xin HU Yongnian HUAnG and Yi ZEnG department of Mechanics and Engineering Science, State Key laboratory for Turbulence research, Peking University, Beijing 100871, China Basic department, Jiaotong University of Eastern China, nanchang 330013, China Dept. of Mechanics and Eng. Science State Key Lab. for Turbulence Res. Peking University Beijing 100871 China Basic department Jiaotong University of Eastern China Nanchang 330013 China

Complex lamellar flow is a typical flow in fluid mechanics. Its research has high theoretical value. Generally speaking, there are only two typical flows in nature: one is Beltrami flow, the other is complex lamellar flow. We have known much about the former. But the solutions of the latter are hard to obtain because it is difficult to solve the n-S equation or Euler equation. From the incompressible condition, if we let the form of the velocity satisfy some special conditions, we would obtain some new solutions of this flow.

关键词： Beltrami flow complex lamellar flow exact solution incompressible condition

Energy and Water Balance at Soil-Air Interface in a Sahelian Region

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2001年第5期18卷 897-909页

作者： Minwei Qian, n. Loglisci, C. Cassardo, A. Longhetto, C. Giraud department of General Physics, University of Turin, Italy Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, Institute of Cosmo-Geophysics, national research Counci department of General Physics University of Turin Turin Italy Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China ICSC-World laboratory Lausanne Switzerland Institute of Cosmo-Geophysics National Research Council (CNR) Turin Italy

The aim of this work is an improvement of the parameterization of the soil moisture in the scheme of the Land Surface Process Model (LSPM) for applications over desert areas. In fact, in very dry conditions, the water vapour flux plays an important role in the evaporation processes and influences the underground profiles of humidity and temperature. The improved version of soil moisture parameterization in the LSPM scheme has been checked by using the data taken from the database of the field experiment HAPEX-Sahel (Hydrology-Atmosphere Pilot Experiment in the Sahel, 1990-1992). Model simulations refer to three dif- ferent stations located in niger (Fallow, Millet and Tiger sites) where input data for LSPM and observations were simultaneously available. The results of simulations, taking into account the water vapour flux in the soil model LSPM, seem to compare better with the observed behaviour of soil moisture and turbulent heat fluxes than those overlooking the water vapour flux, confirming the great importance of the water vapour in such dry conditions.

关键词： Drought Heavy rain Water vapour Soil moisture Evaporation LSPM SVAT HAPEX Sahel niger

The relativistic consistent angular-momentum projected shell model study of the n=Z nucleus ^(52)Fe

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2009年第10期52卷 1471-1476页

作者： LI YanSong1,2 & LOnG GuiLu1,2 1 department of Physics,Tsinghua University,Beijing 100084,China 2 Center of nuclear Theory,national laboratory of Heavy Ion Accelerator of Lanzhou,Lanzhou 730000,China department of Physics Tsinghua University Beijing China Center of nuclear Theory National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou China

The relativistic consistent angular-momentum projected shell model(ReCAPS) is used in the study of the structure and electromagnetic transitions of the low-lying states in the n=Z nucleus *** model calculations show a reasonably good agreement with the *** backbending at 12+ is reproduced and the energy level structure suggests that neutron-proton interactions play important roles.

关键词： ReCAPS relativistic mean field angular-momentum projection method 52Fe neutron-proton interaction

Shape phase transitions in nuclei:Effective order parameters and trajectories

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2011年第S1期54卷 88-97页

作者： ZHAnG Yu1,2, HOU ZhanFeng2 & LIU YuXin2,3 1department of Physics, Liaoning normal University, Dalian 116029, China 2department of Physics and the State Key laboratory of nuclear Physics and Technology, Peking University, Beijing 100871, China 3Center of Theoretical nuclear Physics, national laboratory of Heavy Ion Accelerator, Lanzhou 720000, China department of Physics Liaoning Normal University Dalian China department of Physics and the State Key laboratory of nuclear Physics and Technology Peking University Beijing China Center of Theoretical nuclear Physics National Laboratory of Heavy Ion Accelerator Lanzhou China

We analyze systematically the effective order parameters in nuclear shape phase transition both in experiments and in the interacting boson model. We find that energy ratios and B(E2) ratios can distinguish the first from the second-order phase transition in theory above a certain boson number n (about 50), but in experiments, only those quantities, such as E(L1+)/E(02+) and B(E2; (L+2)1 → L1)/B(E2; 21 → 01), etc., of which the monotonous transitional behavior in the second-order phase transition is broken in the first order phase transition independent of n, are qualified as the effective order parameters. By implementing the originally proposed effective order parameters and the new ones, we find that the isotones with neutron number nn = 62 are a trajectory of the second order phase transition. In addition, we predict that the transitional behavior of isomer shifts of Xe, Ba isotopes and nn = 62 isotones is approximately monotonous due to the finiteness of nuclear system.

关键词： nuclear shape phase transition interacting boson model effective order parameter finite particle number effect transition trajectory