1,565 research outputs found
Group velocity and causality in standard relativistic resistive magnetohydrodynamics
Group velocity of electromagnetic waves in plasmas derived by standard
relativistic resistive MHD (resistive RMHD) equations is superluminal. If we
assume that the group velocity represents the propagation velocity of a signal,
we have to worry about the causality problem. That is, some acausal phenomena
may be induced, such that information transportation to the absolute past and
spontaneous decrease in the entropy. Here, we tried to find the acausal
phenomena using standard resistive RMHD numerical simulations in the suggested
situation of the acausal phenomena. The calculation results showed that even in
such situations no acausal effect happens. The numerical result with respect to
the velocity limit of the information transportation is consistent with a
linear theory of wave train propagation. Our results assure that we can use
these equations without problems of acausal phenomena.Comment: 28 pages, 10 figure
Steady, oscillatory, and unsteady subsonic Aerodynamics, production version 1.1 (SOUSSA-P1.1). Volume 2: User/programmer manual
A user/programmer manual for the computer program SOUSSA P 1.1 is presented. The program was designed to provide accurate and efficient evaluation of steady and unsteady loads on aircraft having arbitrary shapes and motions, including structural deformations. These design goals were in part achieved through the incorporation of the data handling capabilities of the SPAR finite element Structural Analysis computer program. As a further result, SOUSSA P possesses an extensive checkpoint/ restart facility. The programmer's portion of this manual includes overlay/subroutine hierarchy, logical flow of control, definition of SOUSSA P 1.1 FORTRAN variables, and definition of SOUSSA P 1.1 subroutines. Purpose of the SOUSSA P 1.1 modules, input data to the program, output of the program, hardware/software requirements, error detection and reporting capabilities, job control statements, a summary of the procedure for running the program and two test cases including input and output and listings are described in the user oriented portion of the manual
Development of a Time Projection Chamber Using Gas Electron Multipliers (GEM-TPC)
We developed a prototype time projection chamber using gas electron
multipliers (GEM-TPC) for high energy heavy ion collision experiments. To
investigate its performance, we conducted a beam test with 3 kinds of gases
(Ar(90%)-CH4(10%), Ar(70%)-C2H6(30%) and CF4). Detection efficiency of 99%, and
spatial resolution of 79 m in the pad-row direction and 313 m in the
drift direction were achieved. The test results show that the GEM-TPC meets the
requirements for high energy heavy ion collision experiments. The configuration
and performance of the GEM-TPC are described.Comment: 18 pages, 12 figures, published online in Nucl. Instr. and Meth.
Handover Algorithm based VLP using Mobility Prediction Database for Vehicular Network
This paper proposes an improved handover algorithm method for vehicle location prediction (VLP-HA) using mobility prediction database. The main advantage of this method is the mobility prediction database is based on real traffic data traces. Furthermore, the proposed method has the ability to reduce handover decision time and solve resource allocation problem. The algorithm is simple and can be computed very rapidly; thus, its implementation for a high-speed vehicle is possible. To evaluate the effectiveness of the proposed method, QualNet simulation is carried out under different velocity scenarios. Its performance is compared with conventional handover method. The superiority of the proposed method over conventional handover method in deciding the best handover location and choosing candidate access points is highlighted by simulation. It was found that VLP-HA has clearly reduced handover delay by 45% compared to handover without VLP, give high accuracy, hence low complexity algorithm
Simultaneous Excitation of Spins and Pseudospins in the Bilayer Quantum Hall State
The tilting angular dependence of the energy gap was measured in the bilayer
quantum Hall state at the Landau level filling by changing the density
imbalance between the two layers. The observed gap behavior shows a continuous
transformation from the bilayer balanced density state to the monolayer state.
Even a sample with 33 K tunneling gap shows the same activation energy anomaly
reported by Murphy {\it et al.}. We discuss a possible relation between our
experimental results and the quantum Hall ferromagnet of spins and pseudospins.Comment: 4 pages, 4 figure
- …