检索结果-南通市图书馆

Advances in the kinetics of heat and mass transfer in near-continuous complex flows

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of physics 2024年第4期19卷 187-234页

作者：许爱国张德佳甘延标 National Key Laboratory of computational physics Institute of Applied Physics and Computational MathematicsP.O.Box 8009-26Beijing 100088China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China State Key Laboratory for GeoMechanics and Deep Underground Engineering China University of Mining and TechnologyBeijing 100083China National Key Laboratory of Shock Wave and Detonation physics Mianyang 621999China Hebei Key Laboratory of Trans-Media Aerial Underwater Vehicle School of Liberal Arts and SciencesNorth China Institute of Aerospace EngineeringLangfang 065000China

The study of macro continuous flow has a long ***,the exploration of heat and mass transfer in small systems with a particle number of several hundred or less has gained significant interest in the fields of statistical physics and nonlinear ***,due to absence of suitable methods,the understanding of mesoscale behavior situated between the aforementioned two scenarios,which challenges the physical function of traditional continuous fluid theory and exceeds the simulation capability of microscopic molecular dynamics method,remains considerably *** greatly restricts the evaluation of effects of mesoscale behavior and impedes the development of corresponding regulation *** access the mesoscale behaviors,there are two ways:from large to small and from small to *** the necessity to interface with the prevailing macroscopic continuous modeling currently used in the mechanical engineering community,our study of mesoscale behavior begins from the side closer to the macroscopic continuum,that is from large to *** on some fundamental challenges encountered in modeling and analysis of near-continuous flows,we review the research progress of discrete Boltzmann method(DBM).The ideas and schemes of DBM in coarse-grained modeling and complex physical field analysis are *** relationships,particularly the differences,between DBM and traditional fluid modeling as well as other kinetic methods are *** verification and validation of the method,some applied researches including the development of various physical functions associated with discrete and non-equilibrium effects are *** directions of DBM related studies are indicated.

关键词： near-continuous flow non-equilibrium kinetics discrete Boltzmann method complex physical field analysis

Stability analysis of viscous Z-pinch plasma with a sheared axial flow

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese physics B 2008年第8期17卷 2994-3002页

作者：张扬丁宁 institute of applied physics and computational mathematics PO Box 8009

Within the magnetohydrodynamics （MHD） frame, we analyse the effect of viscosity on magneto-Rayleigh Taylor （MRT） instability in a Z-pinch configuration by using an exact method and an approximate method separately. It is demonstrated that the plasma viscosity indeed has a stabilization effect on the MRT mode in the whole wavenumber region, and its influence increases with the perturbation wavenumber increasing. After the characteristics and feasibility of the approximate method have been investigated, we apply it to the stability analysis of viscous plasma where a sheared axial flow （SAF） is involved, and we attain an analytical dispersion relation. It is suggested that the viscosity and the SAF are complemental with each other, and a wide wavenumber range of perturbation is possible to be restrained if the SAF and the viscosity are large enough. Finally, we calculate the possible value of viscosity parameter according to the current experimental conditions, and the results show that since the value of viscosity is much less than the threshold value, its mitigation effect is small enough to be neglected. The role of the viscosity in the stabilization becomes considerable only if special techniques are so developed that the Z-pinch plasma viscosity can be increased greatly.

关键词： Z-pinch magneto-Rayleigh-Taylor (MRT) instability viscosity sheared axial flow

Simulation of Z-Pinch Processes of Nested Tungsten Wire-Array on Angara-5-1 Facility

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chinese physics Letters 2006年第7期23卷 1857-1860页

作者：宁成丁宁刘全杨震华范文斌张扬 institute of applied physics and computational mathematics PO Box 8009 Beijing 100088 Laboratory of computational physics Institute of Applied Physics and Computational Mathematics PO Box 8009 Beijing 100088

Based on the hydrodynamic shell-on-shell collision model, the Z-pinch processes of nested tungsten wire-array in Sino-Russian joint experiments on Angara-5-1 facility are simulated by means of our one-dimensional three-temperature radiation magneto-hydrodynamic code. The results show the evolutions of x-ray radiation burst, implosion trajectories of interfaces, current transfer in inner and outer wire-array plasmas, and the temporal and spatial changes of magnetic field and current density in the process. About 20% of the total driven current is transferred into the inner wire-array plasma by convection and diffusion of magnetic field when the two shells are pinched closest. Compared to the measured x-ray power, the simulated full width at half maximum and time at the strongest radiation agree approximately with the measured values. It is also demonstrated in our simulation that the radiation of nested wire-array Z-pinch is enhanced. The effects of fluctuations of driven current on yields of x-ray are also investigated.

关键词： Z-Pinch Processes Nested Tungsten Wire-Array Angara-5-1 Facility

Influence of erbium on structural,and charged particles,photons,and neutrons shielding properties of Ba_(1-x)Er_(x)SnO_(3) perovskite ceramics

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 Rare Earths 2024年第4期42卷 724-732页

作者： M.K.h.Hamad Nidal Dwaikat M.H.A.Mhareb M.I.Sayyed R.M.Hamad Y.S.M.Alajerami M.A.Almessiere Gameel Saleh Ahmad Hussein Alomari K.A.Ziq Department of Basic Sciences School of Social and Basics SciencesAl Hussein Technical UniversityKing Abdullah II St 242Amman11831Jordan Department of physics College of Engineering and PhysicsInterdisciplinary Research Center for Advanced MaterialsKing Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia Department of physics College of ScienceImam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia Basic and applied Scientific Research Center Imam Abdulrahman Bin Faisal UniversityP0.Box 1982Dammam31441Saudi Arabia Department of physics Faculty of ScienceIsra UniversityAmman11622Jordan Department of Nuclear Medicine Research Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityPo.Box 1982Dammam31441Saudi Arabia Medical Imaging Department Applied Medical Sciences FacultyAl Azhar University-Gaza CityPo.Box 1277Palestine Department of Biophysics Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityPo.Box1982Dammam 31441Saudi Arabia Department of Biomedical Engineering College of EngineeringImam Abdulrahman Bin Faisal UniversityPo.Box 1982Dammam31441Saudi Energy&Minerals Regulatory Commission Amman11821Jordan

Five perovskite ceramics samples of Ba_(1-x)Er_(x)SnO_(3) with x=0.00,0.05,0.10,0.15,and 0.20 were synthesized using the conventional solid-state reaction *** prepared samples were characterized by X-ray diffraction(XRD),Fourier transforms infrared(FTIR),and UV-Vis *** shielding properties against ionizing radiation were also *** XRD analysis shows the perovskite cubic structure as the major phase in all *** FTIR reveals a distinctive band around 614-620 cm^(-1) ascribed to the antisymmetric O-Sn-O ***-Vis spectroscopy was used to determine the bandgap according to diffuse reflectance,and the results display a fixed enhancement in the bandgap from 3.2 to 3.3 eV for all ***-ray shielding properties of the synthesized samples were experimentally measured and compared with XCOM computational *** relative differences(Δ,%)between experimental and theo retical values are low and fall within the 0.446%-7.10%*** addition of Er leads to the enhanced density,neutron,and gamma shielding *** contrast,charged particles’shielding parameters gradually reduce with rising Er *** results suggest that Ba_(1-x)Er_(x)SnO_(3) samples can be used in different radiation shielding applications.

关键词： Perovskite Ceramics Gamma ray shielding Mass stopping power Rare earths

Dynamics of Efficiency Change by Temperature in Diode Pumped Nd：YAG Heat Capacity Laser

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chinese physics Letters 2007年第7期24卷 1930-1933页

作者：壬小军唐兵束小建 institute of applied physics and computational mathematics PO Box 8009-11 Beijing 100088

We investigate the influence of temperature on the efficiency of diode pumped Nd：YAG heat capacity laser is studied. It is shown that the efficiency of such a laser system is greatly reduced at higher temperature. This bad behaviour is mainly caused by the doped-ion redistribution among various Stark levels of the ground state, and by a thermal equilibrium between the upper laser level and the pump level. Meanwhile, the thermal excitations from the ground state to the lower laser level also play a role. We derive a model to describe those effects, with the considerations of emission spectrum of laser diodes, the subtle Stark structures and the linewidth of absorption and of simulated-emission.

关键词： SOLID-STATE LASERS ABSORPTION

polarization of Radiation Emitted after Electron Impact Excitation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese physics Letters 2007年第6期24卷 1560-1562页

作者：吴泽清李月明段斌颜君张弘 Laboratory of computational physics Institute of Applied Physics and Computational Mathematics PO Box 8009-57 Beijing 100088

A programme is developed to calculate the polarizations of the radiation emitted after electron impact excitation. The fully relativistic distorted-wave method is used in cross-section calculations. The programme is applied to He- and Li-like ions. The calculated values of line polarization are compared with other theoretical results and experimental values. For He-like U, at lower incident energy, the present polarization agrees with the other theoretical ones within 1%, while at higher energy, the differences increase up to about 10%. For He-like Fe and Ti, the present results of polarization degree for most of the lines agree with the experimental data within the experimental error bars. For the Li-like Ti line q （ls2s2p^2p3/2 to ls^22s）, the present value of the polarization agree excellently with another theoretical one, and both the values are consistent with the measured data within the experimental error bar.

关键词： RAY-LINE poLARIZATION HIGHLY-CHARGED IONS HE-LIKE FE-XXV MAGNETICSUBLEVELS CROSS-SECTIONS BEAM SPECTROSCOPY TRANSITIONS EMISSION

Multi-Configuration Distorted-Wave Approximation in Electron-Impact Ionization of Ar^2＋

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese physics Letters 2005年第10期22卷 2542-2545页

作者：曾思良李萍方泉玉邱玉波李月明颜君王建国 Key Laboratory of computational physics Institute of Applied Physics and Computational Mathematics PO Box 8009-57 Beijing 100088

A quasi-relativistic distorted-wave approximation is developed to investigate the direct electron-impact ionization processes, in which the configuration interactions are considered in the initial and final states of target. As an example, the direct detailed-level electron-impact ionization cross sections for the ground and low excited states of Ar^6＋（3s^2, 3p^2, 3s3d） are calculated in the energy range from 1.02 to 15Ith （ Ith the ionization threshold）. Comparison with the available data demonstrates that our results are reasonable. The effects of configuration interactions are discussed, and the validity of transformation principles by statistical weights between configuration-averaged and detailed-level electron-impact ionization cross sections is analysed.

关键词： Multi-Configuration Distorted-Wave Approximation

Lévy Stable Distribution and [0, 2] power Law Dependence of Acoustic Absorption on Frequency in Various Lossy Media

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese physics Letters 2005年第10期22卷 2601-2603页

作者：陈文 National Key Laboratory of computational physics Institute of Applied Physics and Computational Mathematics PO Box 8009 Beijing 100088

Absorption of acoustic wave propagation in a large variety of lossy media is characterized by an empirical power law function of frequency, α0｜ω＋^Ⅳ. It has long been noted that the exponent y ranges from 0 to 2 for diverse media. Recently, the present author J. Acoust. Soc. Am. 115 （2004） 1424] developed a fractional Laplacian wave equation to accurately model the power law diss^aation, which can be further reduced to the fractional Laplacian diffusion equation. The latter is known underlying the Lévy stable distribution theory. Consequently, the parameters y is found to be the Lévy stability index, which is known to be bounded within 0 〈 y ≤2. This finding first provides a theoretical explanation of empirical observations y ∈ [0, 2]. Statistically, the frequencydependent absorption can thus be understood a Lévy stable process, where the parameter y describes the fractal nature of attenuative media.

关键词： Lévy Stable Distribution Acoustic Absorption

Comparison Study on Characteristic Regimes in Shocked porous Materials

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese physics Letters 2010年第2期27卷 209-212页

作者：许爱国张广财李华朱建士 National Key Laboratory of computational physics Institute of Applied Physics and Computational MathematicsPO Box 8009-26Beijing 100088

We perform a comparison study on characteristic regimes in shocked porous materials whose mechanical properties cover a wide range. Via the Minkowski functional analysis, it is found that different materials may show the same fractional size of characteristic regimes in the shock-loading procedure, even if one uses the same threshold value to define those regimes. Characteristic regimes in the material with larger initial yield are more dispersed. For a fixed shock strength, there exists a material strength with which the shock wave reaction contributes the maximum plastic work. With the decreasing of shock strength, this material strength becomes smaller. These observations may present helpful indications for new material designs.

关键词： Condensed matter: structural mechanical & thermal