2,559 research outputs found
A note on Maxwell's equal area law for black hole phase transition
The state equation of the charged AdS black hole is reviewed in the
plane. Thinking of the phase transition, the , , graphs are
plotted and then the equal area law is used in the three cases to get the phase
transition point (P,T). The analytical phase transition point relations for P-T
of charged AdS black hole has been obtained successfully. By comparing the
three results, we find that the equal area law possibly cannot be used directly
for plane. According to the , results, we plot the
graph and find that for a highly charged black hole a very low temperature
condition is required for the phase transition
A New Phase Transition Related to the Black Hole's Topological Charge
The topological charge of AdS black hole is introduced in
Ref.[1,2], where a complete thermodynamic first law is obtained. In this paper,
we investigate a new phase transition related to the topological charge in
Einstein-Maxwell theory. Firstly, we derive the explicit solutions
corresponding to the divergence of specific heat and determine
the phase transition critical point. Secondly, the curve and curve
are investigated and they exhibit an interesting van der Waals system's
behavior. Critical physical quantities are also obtained which are consistent
with those derived from the specific heat analysis. Thirdly, a van der Waals
system's swallow tail behavior is observed when in the
graph. What's more, the analytic phase transition coexistence lines are
obtained by using the Maxwell equal area law and free energy analysis, the
results of which are consistent with each other.Comment: 11 pages, 5 figure
A blind adaptive projection receiver for CDMA systems
Journal ArticleAbstract - This paper presents a blind and adaptive CDMA receiver that does not require knowledge of the spreading codes associated with users other than the ones of interest. Receivers for synchronous as well as asynchronous transmission by multiple users with error control coding are developed. Simulation results demonstrating that the receivers suffer negligible performance loss over systems with complete knowledge of all the spreading codes are included in the paper
Adaptive, quadratic preprocessing of document images for binarization
Journal ArticleAbstract-This paper presents an adaptive algorithm for preprocessing document images prior to binarization in character recognition problems. Our method is similar in its approach to the blind adaptive equalization of binary communication channels. The adaptive filter utilizes a quadratic system model to provide edge enhancement for input images that have been corrupted by noise and other types of distortions during the scanning process. Experimental results demonstrating significant improvement in the quality of the binarized images over both direct binarization and a previously available preprocessing technique are also included in the paper
An adaptive channel estimator for CDMA systems in multipath fading channels
Journal ArticleABSTRACT CDMA systems in multipath fading channels need to estimate channel parameters for coherent detection of the transmitted signals. In this paper we present a simple but effective channel estimation algorithm that can be incorporated into most types of multiuser receivers to obtain good detection performance. This technique uses a set of correlation filters to independently estimate each of the channel parameters. One advantage our method has over subspace-based algorithms for channel estimation is that it can estimate the channel parameters without phase or amplitude ambiguity. Simulation results demonstrating that our channel estimator is capable of tracking reasonably fast fading channels are also presented in the paper
Attractive Interaction between Vortex and Anti-vortex in Holographic Superfluid
Annihilation process of a pair of vortices in holographic superfluid is
numerically simulated. The process is found to consist of two stages which are
amazingly separated by vortex size . The separation distance
between vortex and anti-vortex as a function of time is well fitted by , where the scaling exponent for , and
for . Then the approaching velocity and acceleration as
functions of time and as functions of separation distance are obtained. Thus
the attractive force between vortex and anti-vortex is derived as
for the first stage, and for the second stage. In the end, we explained why the
annihilation rate of vortices in turbulent superfluid system obeys the two-body
decay law when the vortex density is low.Comment: 14 pages, 5 figure
A blind projection receiver for coded CDMA systems
Journal ArticleABSTRACT This paper presents a blind adaptive CDMA receiver that requires no knowledge of the spreading codes, the delays, and the energy of the received signals associated with the interfering users. Our receiver is based on linear interference cancellation and adaptive interference signal subspace tracking. It has error control coding embedded in the detector structure and employs "branch processing" to detect the bit stream. Simulation results demonstrating that the receiver suffers negligible performance loss over systems with complete knowledge of the interfering users are presented in the paper
- …