Evaluating the Efficiency of Video Transmission Using a New Circular Search Algorithm Based on the Motion Estimation for a Single User

ويواجه البث الناجح للفيديو عبر الشبكات اللاسلكية العديد من التحديات والمشاكل التي تسهم في إضعاف أنظمة الإرسال الفعالة بسبب محدودية الموارد والبيئة المحيطة بالإشارة اللاسلكية. لذلك، من أجل التعامل مع هذه التحديات نحن بحاجة ليس فقط لضغط الفيديو بطرق فعالة ولكن أيضا لاستخدام نظام نقل جيد التغلب على أخطاء القناة وتصحيح الأخطاء المحتملة أثناء عملية الإرسال. وفي هذه الورقة، يعتمد نظام الإرسال على إرسال الفيديو إلى مستعمل واحد، ويضاف نظام مقترح لمحاكاة الإرسال في الشبكات المتنقلة وقياس كفاءة نظام الإرسال إلى نسبة الضوضاء (أي أبيض مضاف قنوات الضوضاء. وفي كثير من هذه الأنظمة العملية، يمكن أن يحسن المصدر المشترك والقناة التي تشفر كفاءة وأداء نظام الإرسال تحسنا كبيرا للحصول على نظام إرسال دون أخطاء في القناة. ويؤدي تشفير المصدر إلى تقليل التكرار في الإشارة المرسلة لتوفير عرض النطاق ويضيف التشفير القناة / التلافي  تكرارا مفيدا لمكافحة أخطاء القناة. وتستخدم خوارزمية البحث الدائرية لتقدير الحركة  كطريقة ترميز المصدر. وتظهر النتائج أن النظام المقترح يمكن أن يحقق التوازن بين أداء الضغط والحفاظ على جودة الفيديو. وأظهرت الأساليب المستخدمة في عملية الإرسال ميزة كبيرة في أداء تشفير القناة مقارنة بأداء نظام إرسال آخر دون تشفير القناة    The successful transmission of video over wireless networks faces many challenges and problems that contribute to the weakening of efficient transmission systems because of the limited resources and the environment surrounding the wireless signal. Therefore, In order to deal with these challenges we need not only to compress the video in efficient ways but also to use a good transmission system that overcome the errors of the channel and correct potential errors during the transmission process. In this paper, the transmission system depends on the transmission of the video to a single user, a proposed system to simulate the transmission in the mobile networks and to measure the efficiency of the transmission system is added to the percentage of noise (i.e. additive white Gaussian Noise (AWGN) channels). In many such practical systems, jointly source and channel coding the efficiency and performance of the transmission system can be greatly improved to obtain a transmission system without channel errors. The source coding decreases the redundancy in the signal sent to provide bandwidth and the channel/convolutional coding (CC) adds useful redundancy to combat channel errors. The circular search algorithm for motion estimation (ME) is used as a source coding method. The results show that the suggested system can produce a balance among the compression performance and maintain video quality. The methods used in the transmission process showed a great advantage in the performance of the channel encoding compared to that of another transmission system without channel coding

Scale Anomaly and Quantum Chaos in the Billiards with Pointlike Scatterers

We argue that the random-matrix like energy spectra found in pseudointegrable billiards with pointlike scatterers are related to the quantum violation of scale invariance of classical analogue system. It is shown that the behavior of the running coupling constant explains the key characteristics of the level statistics of pseudointegrable billiards.Comment: 10 pages, RevTex file, uuencode

Spectral transitions in networks

We study the level spacing distribution p(s) in the spectrum of random networks. According to our numerical results, the shape of p(s) in the Erdos-Renyi (E-R) random graph is determined by the average degree , and p(s) undergoes a dramatic change when is varied around the critical point of the percolation transition, =1. When > 1, the p(s) is described by the statistics of the Gaussian Orthogonal Ensemble (GOE), one of the major statistical ensembles in Random Matrix Theory, whereas at =1 it follows the Poisson level spacing distribution. Closely above the critical point, p(s) can be described in terms of an intermediate distribution between Poisson and the GOE, the Brody-distribution. Furthermore, below the critical point p(s) can be given with the help of the regularised Gamma-function. Motivated by these results, we analyse the behaviour of p(s) in real networks such as the Internet, a word association network and a protein protein interaction network as well. When the giant component of these networks is destroyed in a node deletion process simulating the networks subjected to intentional attack, their level spacing distribution undergoes a similar transition to that of the E-R graph.Comment: 11 pages, 5 figure

Experimental and numerical investigation of the reflection coefficient and the distributions of Wigner's reaction matrix for irregular graphs with absorption

We present the results of experimental and numerical study of the distribution of the reflection coefficient P(R) and the distributions of the imaginary P(v) and the real P(u) parts of the Wigner's reaction K matrix for irregular fully connected hexagon networks (graphs) in the presence of strong absorption. In the experiment we used microwave networks, which were built of coaxial cables and attenuators connected by joints. In the numerical calculations experimental networks were described by quantum fully connected hexagon graphs. The presence of absorption introduced by attenuators was modelled by optical potentials. The distribution of the reflection coefficient P(R) and the distributions of the reaction K matrix were obtained from the measurements and numerical calculations of the scattering matrix S of the networks and graphs, respectively. We show that the experimental and numerical results are in good agreement with the exact analytic ones obtained within the framework of random matrix theory (RMT).Comment: 15 pages, 8 figure

Seizure characterisation using frequency-dependent multivariate dynamics

The characterisation of epileptic seizures assists in the design of targeted pharmaceutical seizure prevention techniques and pre-surgical evaluations. In this paper, we expand on recent use of multivariate techniques to study the crosscorrelation dynamics between electroencephalographic (EEG) channels. The Maximum Overlap Discrete Wavelet Transform (MODWT) is applied in order to separate the EEG channels into their underlying frequencies. The dynamics of the cross-correlation matrix between channels, at each frequency, are then analysed in terms of the eigenspectrum. By examination of the eigenspectrum, we show that it is possible to identify frequency dependent changes in the correlation structure between channels which may be indicative of seizure activity. The technique is applied to EEG epileptiform data and the results indicate that the correlation dynamics vary over time and frequency, with larger correlations between channels at high frequencies. Additionally, a redistribution of wavelet energy is found, with increased fractional energy demonstrating the relative importance of high frequencies during seizures. Dynamical changes also occur in both correlation and energy at lower frequencies during seizures, suggesting that monitoring frequency dependent correlation structure can characterise changes in EEG signals during these. Future work will involve the study of other large eigenvalues and inter-frequency correlations to determine additional seizure characteristics

Initial Value Problems and Signature Change

We make a rigorous study of classical field equations on a 2-dimensional signature changing spacetime using the techniques of operator theory. Boundary conditions at the surface of signature change are determined by forming self-adjoint extensions of the Schr\"odinger Hamiltonian. We show that the initial value problem for the Klein--Gordon equation on this spacetime is ill-posed in the sense that its solutions are unstable. Furthermore, if the initial data is smooth and compactly supported away from the surface of signature change, the solution has divergent $L^2$-norm after finite time.Comment: 33 pages, LaTeX The introduction has been altered, and new work (relating our previous results to continuous signature change) has been include

Level statistics and eigenfunctions of pseudointegrable systems: dependence on energy and genus number

We study the level statistics (second half moment $I_0$ and rigidity $\Delta_3$) and the eigenfunctions of pseudointegrable systems with rough boundaries of different genus numbers $g$. We find that the levels form energy intervals with a characteristic behavior of the level statistics and the eigenfunctions in each interval. At low enough energies, the boundary roughness is not resolved and accordingly, the eigenfunctions are quite regular functions and the level statistics shows Poisson-like behavior. At higher energies, the level statistics of most systems moves from Poisson-like towards Wigner-like behavior with increasing $g$. Investigating the wavefunctions, we find many chaotic functions that can be described as a random superposition of regular wavefunctions. The amplitude distribution $P(\psi)$ of these chaotic functions was found to be Gaussian with the typical value of the localization volume $V_{\rm{loc}}\approx 0.33$. For systems with periodic boundaries we find several additional energy regimes, where $I_0$ is relatively close to the Poisson-limit. In these regimes, the eigenfunctions are either regular or localized functions, where $P(\psi)$ is close to the distribution of a sine or cosine function in the first case and strongly peaked in the second case. Also an interesting intermediate case between chaotic and localized eigenfunctions appears

Self-pulsing effect in chaotic scattering

We study the quantum and classical scattering of Hamiltonian systems whose chaotic saddle is described by binary or ternary horseshoes. We are interested in parameters of the system for which a stable island, associated with the inner fundamental periodic orbit of the system exists and is large, but chaos around this island is well developed. In this situation, in classical systems, decay from the interaction region is algebraic, while in quantum systems it is exponential due to tunneling. In both cases, the most surprising effect is a periodic response to an incoming wave packet. The period of this self-pulsing effect or scattering echoes coincides with the mean period, by which the scattering trajectories rotate around the stable orbit. This period of rotation is directly related to the development stage of the underlying horseshoe. Therefore the predicted echoes will provide experimental access to topological information. We numerically test these results in kicked one dimensional models and in open billiards.Comment: Submitted to New Journal of Physics. Two movies (not included) and full-resolution figures are available at http://www.cicc.unam.mx/~mejia

Statistical Properties of Cross-Correlation in the Korean Stock Market

We investigate the statistical properties of the correlation matrix between individual stocks traded in the Korean stock market using the random matrix theory (RMT) and observe how these affect the portfolio weights in the Markowitz portfolio theory. We find that the distribution of the correlation matrix is positively skewed and changes over time. We find that the eigenvalue distribution of original correlation matrix deviates from the eigenvalues predicted by the RMT, and the largest eigenvalue is 52 times larger than the maximum value among the eigenvalues predicted by the RMT. The $\beta_{473}$ coefficient, which reflect the largest eigenvalue property, is 0.8, while one of the eigenvalues in the RMT is approximately zero. Notably, we show that the entropy function $E(\sigma)$ with the portfolio risk $\sigma$ for the original and filtered correlation matrices are consistent with a power-law function, $E(\sigma) \sim \sigma^{-\gamma}$, with the exponent $\gamma \sim 2.92$ and those for Asian currency crisis decreases significantly

Resonances of the Frobenius-Perron Operator for a Hamiltonian Map with a Mixed Phase Space

Resonances of the (Frobenius-Perron) evolution operator P for phase-space densities have recently attracted considerable attention, in the context of interrelations between classical and quantum dynamics. We determine these resonances as well as eigenvalues of P for Hamiltonian systems with a mixed phase space, by truncating P to finite size in a Hilbert space of phase-space functions and then diagonalizing. The corresponding eigenfunctions are localized on unstable manifolds of hyperbolic periodic orbits for resonances and on islands of regular motion for eigenvalues. Using information drawn from the eigenfunctions we reproduce the resonances found by diagonalization through a variant of the cycle expansion of periodic-orbit theory and as rates of correlation decay.Comment: 18 pages, 7 figure