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This paper describes scalable convex optimization methods for phase retrieval. The main characteristics of these methods are the cheap per-iteration complexity and the low-memory footprint. With a variant of the original PhaseLift formulation, we first illustrate how to leverage the scalable Frank-Wolfe (FW) method (also known as the conditional gradient algorithm), which requires a tuning parameter...
The complexity and dynamicity of interdisciplinary research clusters requires an efficient management in order to ensure a good performance. Therefore, this paper presents an iterative regulatory process for managing interdisciplinary research clusters which has been implemented at the two clusters of excellence at RWTH Aachen University. Thereby, an annual evaluation of the cluster performance through...
Realistic map data is the basis for meaningful simulation studies of Inter-Vehicle Communication (IVC) applications and protocols [1]. Synthetic scenarios such as isolated intersections or a perfectly laid-out grid do not feature the typical mix of low and high traffic density roads and can therefore not be used as a representative scenario for (sub)urban traffic [2].
Linear filtering methods are well known and have been successfully applied in system identification and equalization problems. However, they become unpractical when the number of parameters to estimate is very large. The recently proposed assumption of system separability allows the development of computationally efficient alternatives to classic adaptive methods in this scenario. In this work, we...
In this work we shed light on the problem of precoding and user selection in MIMO networks. We formulate the problem using the framework of stable matching, whereby a set of users wish to be matched to a set of serving base stations, such as to maximize the sum-rate performance of the system. Though the problem is NP-hard, we propose a suboptimal heuristic that tackles the problem in a distributed...
In this paper, we present a complexity study of the Gamma correction method for automatic text extraction from complex images. This study is based on the build of a simple and adequate algorithm for future hardware solution. Then, a profiling study for each function of the proposed solution was done. After validation, using C/C++ environment, a comparison with the OpenCV based algorithm developed...
High Efficiency Video Coding (HEVC) is a novel video compression standard. It provides significantly better performance than its predecessor, but introduces high computational complexity due its hierarchical block structure. Determining Coding Units (CU), Prediction Units (PU), and Transform Units (TU) size is a time consuming process, as block partitioning decisions are based on rate-distortion optimization...
The High Efficiency Video Coding (HEVC) standard achieves higher encoding efficiency than previous standards such as H.264/AVC. One key contributor to this improvement is the intra-prediction method that supports a large number of prediction directions at a cost of high computational complexity. Within the context of mobile devices with limited power and computational capabilities, reductions on encoding...
In this paper, we propose an extension of our mining-based SAT compression framework to constraint satisfaction problem (CSP). We consider n-ary extensional constraints (table constraints). Our approach aims to reduce the size of the CSP by exploiting the structure of the constraints graph and its associated microstructure. More precisely, we apply itemset mining techniques to search for closed frequent...
Pointwise matches between two time series are of great importance in time series analysis, and dynamic time warping (DTW) is known to provide generally reasonable matches. There are situations where time series alignment should be invariant to scaling and offset in amplitude or where local regions of the considered time series should be strongly reflected in pointwise matches. Two different variants...
The energy requirements of cities' inhabitants have grown during the last decade. Recent studies justify the necessity of reducing the energy consumption/emissions in cities. The present paper gives an overview of the factors affecting the energy consumption of the citizens based on studies conducted in cities across the globe. The studies cover all the factors that affect citizens' mobility choice...
Polar codes for channels with memory are considered in this paper. Şaşoğlu proved that Arikan's polarization applies to finite-state memory channels but practical decoding algorithms of polar codes for such channels have been unknown. This paper proposes a generalization of successive cancellation algorithm for channels with memory where the complexity is polynomial in the number of states. In addition,...
We develop an information-theoretic framework that explores the identifiability of top-K ranked items. The goal of the problem considered herein is to recover a consistent ordering that emphasizes the top-K ranked items, based on partially revealed preferences. Under the Bradley-Terry-Luce model that postulates a set of latent preference scores underlying all items and the odds of paired comparisons...
Locally correctable codes are error-correcting codes that allow a single bit of the codeword to be recovered by looking up a small subset of the coordinates of the received word. In this work, we generalize the concept of traditional locally correcting to locally correcting multiple bits, and present a family of codes which allow multiple bits to be recovered with probability approaching 1 by visiting...
We consider the complexities of repair algorithms for locally repairable codes and propose a class of codes that repair single node failures using addition operations only, or codes with addition based repair. We construct two families of codes with addition based repair. The first family attains distance one less than the Singleton-like upper bound, while the second family attains the Singleton-like...
In network coding theory, when wiretapping attacks occur, secure network coding is introduced to prevent information from being leaked to adversaries. In practical network communications, secure constraints vary with time. How to effectively deal with information transmission and information security simultaneously under different security-levels is introduced in this paper as variable-security-level...
Product lifecycles are getting increasingly shorter, but the lifecycles of industrial automation systems remain stable. Since future requirements for the industrial automation systems made by the market are often unknown at the beginning of the planning process, industrial automation systems have to be adaptable at later times. In addition, the efforts of planning should be reduced continuously without...
In this paper, we propose a new rateless code based on overlapped generations. This proposed scheme works very well especially in a broadcast scenario, where channels with different characteristics are involved in the system. In the proposed scheme, we allow the adjacent generations to overlap. Our main focus is on the design of rateless codes to make any receiver able to recover all the source file...
Homomorphic encryption is a novel encryption method for it enables computing over encrypted data. This has a wide range of real world ramifications such as being able to blindly compute a search result sent to a remote server without revealing it's content. In this paper we summarize how SQL queries can be made secure using a homomorphic encryption scheme based on the ideas of Gahi, et al [1]. Gahi's...
The development of wireless sensor networks has inspired great research interest in the design of distributed source coding(DSC) schemes. Among various DSC schemes, distributed arithmetic coding (DAC) is an attractive option due to its low encoding complexity as well as its good performance at short block lengths. Since DAC has only been proposed for binary sources to date, in this paper we propose...
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