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121.
The effect of the Hall current on the magnetohydrodynamic (MHD) natural convection flow from a vertical permeable flat plate with a uniform heat flux is analyzed in the presence of a transverse magnetic field.It is assumed that the induced magnetic field is negligible compared with the imposed magnetic field.The boundary layer equations are reduced to a suitable form by employing the free variable formulation (FVF) and the stream function formulation (SFF).The parabolic equations obtained from FVF are numer... 相似文献
122.
本文介绍一台采用双潘宁型多电荷重离子源的200kV重离子加速器,简述它在GaP光探测器的研制、聚合物材料和金属材料的离子注入改性等方面的研究与应用。 相似文献
123.
Both the electrical and optical properties are studied of the GaN:Si films with carrier concentrations ranging from 10^17cm^-3 to 10^19cm^-3.rhe results indicate that the increase in slope of carrier concentration starts to slow down when the flow rate of SiH4 is larger than 6.38μmol/min, which is attributed to the amphoteric character of Si. At the same time, the photoluminescence results show that the FWHM of UV is widened,which can be interpreted quantitatively with a semi-classic model. Furthermore, the intensity ratio between the yellow and the UV luminescences reduces monotonically with Si dopants increasing. 相似文献
124.
Jerzy Kocik 《Advances in Applied Clifford Algebras》2007,17(1):71-93
We show that the space of Euclid’s parameters for Pythagorean triples is endowed with a natural symplectic structure and that
it emerges as a spinor space of the Clifford algebra R21, whose minimal version may be conceptualized as a 4-dimensional real algebra of “kwaternions.” We observe that this makes
Euclid’s parametrization the earliest appearance of the concept of spinors. We present an analogue of the “magic correspondence”
for the spinor representation of Minkowski space and show how the Hall matrices fit into the scheme. The latter obtain an
interesting and perhaps unexpected geometric meaning as certain symmetries of an Apollonian gasket. An extension to more variables
is proposed and explicit formulae for generating all Pythagorean quadruples, hexads, and decuples are provided. 相似文献
125.
Using a 90mm-bore, 3.15 m long detonation tube, experimental detonation characteristics (detonability limits, detonation
velocities and peak pressures) of stoichiometric methane-oxygen-diluent mixtures at an initial pressure up to 3.5 MPa have
been experimentally investigated. A parametric study has been carried out as a function of both amount and nature of diluent,
namely carbon dioxide, nitrogen and helium. The experimental results allowed the adjustment and validation of computations
of the Chapman-Jouguet characteristics by means of a thermochemical code. These experimental data associated with validated
computations provide a valuable tool, among others, for the choice of the most appropriate mixture composition in the superdetonative
combustion mode for ram accelerator (ramac) experiments. The investigations were organized to determine the upper detonable
areas of dense ternary mixtures, and to provide detonation velocity data in order to adjust a series of intermolecular parameters
involved in the thermochemical code.
Received 8 May 1997 / Accepted 15 December 1997 相似文献
126.
At the new high flux reactor FRM-II in Munich the accelerator MAFF (Munich accelerator for fission fragments) is under design.
In the high neutron flux of 1014 n/cm2 s up to 1014 neutron-rich fission fragments per second are produced in the 1 g U-235 target. Ions with an energy of 30 keV are extracted
from the ion source. In the mass separator two isotopes can be selected. One of the beams is used for low energy experiments,
the other one is injected into an ECRIS (or EBIS) for charge breeding to a q/A≥0.16. A gas filled RFQ cooler is used for emittance improvement. The subsequent LINAC delivers beams with an energy ranging
from 3.7 MeV/u to 5.9 MeV/u. New IH structures are being developed at the Munich tandem laboratory. A small storage ring is
planned in a further stage to recycle the fission fragments. A thin target foil can be placed into this ring, e.g., for synthesis
of super-heavy elements. The through-going beam tube has been installed in the heavy water tank of the reactor. Tests of the
target ion source in a special oven to test long term stability and safety tests were in progress. 相似文献
127.
A. V. Volkozub A. D. Caplin Yibing Huang R. Flü kiger G. Grasso H. Eckelmann M. Quilitz W. Goldacker 《Physica C: Superconductivity and its Applications》1998,310(1-4):159-162
The modelling of both critical and remanent states (i.e., the current density and field distributions) in periodic arrays of flat superconducting strips is important for calculating the AC losses in multifilamentary tapes made for power applications. We model the current and field profiles for such magnetically coupled conductors, and have measured these dependences for BSCCO-22223 tapes using a miniature scanning Hall probe technique. The results indicate that the filaments are also electrically connected to a significant extent, which must be caused by superconducting intergrowths between individual filaments. 相似文献
128.
P N Ostroumov 《Pramana》2002,59(6):895-913
The Nuclear Science Community in the Unites States has unanimously concluded that developments in both nuclear science and
its supporting technologies make building a world-leading Rare-Isotope Accelerator (RIA) facility for production of radioactive
beams the top priority. The RIA development effort involves several US Laboratories (ANL, JLAB, LBNL, MSU, ORNL). The RIA
facility includes a CW 1.4 GeV driver LINAC and a 100 MV post-accelerator both based on superconducting (SC) cavities operating
at frequencies from 48 MHz to 805 MHz. An initial acceleration in both LINACs is provided by room temperature RFQs. The driver
LINAC is designed for acceleration of any ion species; from protons up to 900 MeV to uranium up to 400 MeV/u. The novel feature
of the driver LINAC is an acceleration of multiple charge-state heavy-ion beams in order to achieve 400 kW beam power. Basic
design concepts of the driver LINAC are given. Several new conceptual solutions in beam dynamics, room temperature and SC
accelerating structures for heavy ion accelerator applications are discussed. 相似文献
129.
Tapan Nandi V Nanal W A Fernandes C A Desai M B Kurup K G Prasad P M R Rao S Padmanabhan 《Pramana》1995,44(1):67-76
A facility for carrying out beam-foil spectroscopic studies in the UV and visible region using the 400 kV electrostatic ion
accelerator at Tata Institute of Fundamental Research, Bombay is described. 相似文献
130.
S. Faniel E. Tutuc E.P. De Poortere C. Gustin A. Vlad L. Moldovan S. Melinte M. Shayegan V. Bayot 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):120
We report on low-temperature thermopower measurements of interacting GaAs bilayer hole systems in the limit of no interlayer tunneling. These systems exhibit a reentrant insulating phase near the many-body quantum Hall state (QHS) at total filling factor ν=1, when both layers have the same density. The diffusion thermopower is expected to diverge as T-1 in the presence of an energy gap (Wigner crystal) or to vanish in the case of a disordered induced mobility gap. Our results show that, as the temperature is decreased, the diffusion thermopower exhibits a T-1 dependence in the insulating phase around ν=1. This behavior clearly indicates the opening of an energy gap at low temperature, in agreement with the formation of a pinned Wigner solid. Finally, we report on the T-dependence of the thermopower at ν=1. 相似文献