Decomposition of SU(N) connection and Effective Theory of SU(N) QCD

We give a general decomposition of SU(N) connection and derive a generalized Skyrme-Faddeev action as the effective action of SU(N) QCD in the low energy limit. The result is obtained by separating the topological degrees which describes the non-Abelian monopoles from the dynamical degree of gauge potential, and integrating all the dynamical degrees of SU(N) QCD.Comment: retex, 7 page

Optimal Clustering of Discrete Mixtures: Binomial, Poisson, Block Models, and Multi-layer Networks

In this paper, we first study the fundamental limit of clustering networks when a multi-layer network is present. Under the mixture multi-layer stochastic block model (MMSBM), we show that the minimax optimal network clustering error rate, which takes an exponential form and is characterized by the Renyi divergence between the edge probability distributions of the component networks. We propose a novel two-stage network clustering method including a tensor-based initialization algorithm involving both node and sample splitting and a refinement procedure by likelihood-based Lloyd algorithm. Network clustering must be accompanied by node community detection. Our proposed algorithm achieves the minimax optimal network clustering error rate and allows extreme network sparsity under MMSBM. Numerical simulations and real data experiments both validate that our method outperforms existing methods. Oftentimes, the edges of networks carry count-type weights. We then extend our methodology and analysis framework to study the minimax optimal clustering error rate for mixture of discrete distributions including Binomial, Poisson, and multi-layer Poisson networks. The minimax optimal clustering error rates in these discrete mixtures all take the same exponential form characterized by the Renyi divergences. These optimal clustering error rates in discrete mixtures can also be achieved by our proposed two-stage clustering algorithm

Uber-in-light: Unobtrusive visible light communication leveraging complementary color channel

Abstract: Recently, Visible Light Communication (VLC) over a screen-camera channel has drawn considerable attention to unobtrusive design. It overcomes the distractive nature of traditional coded image approaches (e.g., barcodes). Previous unobtrusive methods fall into two categories: (1) utilizing alpha channel, a well known concept in computer graphics, to encode bits into the pixel translucency change with off-the-shelf smart devices; and (2) leveraging the spatial-temporal flicker-fusion property of human vision system with the fast frame rate of modern displays. However, these approaches heavily rely on high-end devices to achieve both unobtrusive and high accuracy screen-camera-based data communication without affecting video-viewing experience. Unlike previous approaches, we propose Uber-in-light, a novel unobtrusive and accurate VLC system, that enables real-time screen-camera communication, applicable to any screen and camera. The proposed system encodes the data as complementary intensity changes over Red, Green, and Blue (RGB) color channels that could be successfully decoded by camera while leaving the human visual perception unaffected. We design a MFSK modulation scheme with dedicated frame synchronization signal embedded in an orthogonal color channel to achieve high throughput. Furthermore, together with the complementary color intensity, an enhanced MUSIC-based demodulation scheme is developed to ensure highly accurate data transmission. Our user experience experiments confirmed the effectiveness of delivering unobtrusive data across different types of video content and resolutions. Extensive real-time performance evaluations are conducted using our prototype implementation to demonstrate the efficiency and reliability of the proposed system under diverse wireless environments

A full-cooperative diversity beamformingscheme in two-way amplify-and-forward relay systems

AbstractConsider a simple two-way relaying channel in which two single-antenna sources exchange information via a multiple-antenna relay. For such a scenario, all the existing approaches that can achieve full cooperative diversity order are based on antenna/relay selection, for which the difficulty in designing the beamforming lies in the fact that a single beamformer needs to serve two destinations. In this paper, a new full-cooperative diversity beamforming scheme that ensures that the relay signals are coherently combined at both destinations is proposed, and analytical results are provided to demonstrate the performance gains. Moreover, the impact of channel estimation error is also evaluated. Finally, numerical results are provided to verify the accuracy of the provided analytical results, and also to show that this proposed scheme can outperform existing schemes based on antenna selection

Characterizing stress-dependent complex and relaxation moduli of dense graded asphalt mixtures

The objective of this paper is to investigate the stress-dependence of the complex and relaxation moduli of dense graded asphalt mixtures. Complex modulus tests at four different confining pressures were conducted. Then, the stress dependence of the long-term equilibrium modulus of asphalt mixture based on Prony series model was modeled by Uzan model. The Maxwell components of the relaxation modulus were determined by a two-step method. Finally, the stress dependence of the relaxation modulus was quantified by relaxation spectrum of the material. The results show that for the selected dense-graded asphalt mixtures, the dynamic modulus increases, and phase angle decreases with the increasing confining pressures at relatively low reduced loading frequency. However, the stress dependence is insignificant in a relatively high-reduced loading frequency. The Uzan model coefficient of the long-term equilibrium modulus of the relaxation modulus can be determined effectively by the proposed deviatoric stress master curves. To obtain reliable and accurate Maxwell component coefficients, it is recommended that: (a) the measured loss moduli rather than the storage moduli should be used to calculate Maxwell component coefficients if collocation method is utilized, and (b) a log-scaled least squared regression minimization objective should be used as the regression objective for the coefficient determination. The relaxation spectrum of asphalt mixture can be modeled by Gaussian function, where the size of the relaxation spectrum increases but the shape and position of the relaxation spectrum remain unchanged when the confining pressure increases