Robust Linear Regression Analysis - A Greedy Approach

The task of robust linear estimation in the presence of outliers is of particular importance in signal processing, statistics and machine learning. Although the problem has been stated a few decades ago and solved using classical (considered nowadays) methods, recently it has attracted more attention in the context of sparse modeling, where several notable contributions have been made. In the present manuscript, a new approach is considered in the framework of greedy algorithms. The noise is split into two components: a) the inlier bounded noise and b) the outliers, which are explicitly modeled by employing sparsity arguments. Based on this scheme, a novel efficient algorithm (Greedy Algorithm for Robust Denoising - GARD), is derived. GARD alternates between a least square optimization criterion and an Orthogonal Matching Pursuit (OMP) selection step that identifies the outliers. The case where only outliers are present has been studied separately, where bounds on the \textit{Restricted Isometry Property} guarantee that the recovery of the signal via GARD is exact. Moreover, theoretical results concerning convergence as well as the derivation of error bounds in the case of additional bounded noise are discussed. Finally, we provide extensive simulations, which demonstrate the comparative advantages of the new technique

Efficient FPGA implementations of volterra DFES for optical systems

In this work suitable architectures and high-throughput FPGA implementations of Volterra Decision Feedback Equalizers (VDFEs) for optical communication links are presented. Two VDFE configurations were selected based on the available resources of the employed FPGA devices, and two multiplexer-based architectures were developed for each of them in order to achieve the target throughput. The comparison of the experimental results with respect to different VDFE configurations, throughput, and FPGA devices points out the platform-specific design characteristics. The introduced architectures meet the desired 10Gb/s throughput, so it is demonstrated that the FPGA is a suitable platform for high-speed optical fiber communication systems

Big Data Management and Analytics for Mobility Forecasting in datAcron

The exploitation of heterogeneous data sources offering very large historical and streaming data is important to increasing the accuracy of operations when analysing and predicting future states of moving entities (planes, vessels, etc.). This article presents the overall goals and big data challenges addressed by datAcron on big data analytics for time-critical mobility forecasting

Area-throughput trade-offs for SHA-1 and SHA-256 hash functions’ pipelined designs

High-throughput designs of hash functions are strongly demanded due to the need for security in every transmitted packet of worldwide e-transactions. Thus, optimized and non-optimized pipelined architectures have been proposed raising, however, important questions. Which is the optimum number of the pipeline stages? Is it worth to develop optimized designs or could the same results be achieved by increasing only the pipeline stages of the non-optimized designs? The paper answers the above questions studying extensively many pipelined architectures of SHA-1 and SHA-256 hashes, implemented in FPGAs, in terms of throughput/area (T/A) factor. Also, guides for developing efficient security schemes designs are provided. Read More: https://www.worldscientific.com/doi/abs/10.1142/S021812661650032

FPGA implementation of a MIMO DFE in 40 GB/S DQPSK optical links

In this paper, an FPGA implementation of a Multi Input Multi Output (MIMO) Decision Feedback equalizer (DFE) is proposed, for the electronic compensation of the impairments in 40Gb/s Intensity Modulated Direct Detection (IM/DD) optical communication links employing NRZ DQPSK signaling. The proposed equalizer is used for the electronic compensation the residual Chromatic Dispersion (CD) along the installed optically compensated optical paths. The required processing rate is achieved by applying intensive pipelining and parallelism in the original architecture of the equalizer. At the given processing rate, a 8-input 2-output DFE involving three taps feedforward filtering and two taps backward filtering is implemented on a single, cutting edge technology, Xilinx FPGA device

Ανάλυση και βελτιστοποίηση εφοδιαστικής αλυσίδας συλλογής αστικών στερεών απορριμμάτων - εφαρμογή στο δήμο κορυδαλλού

150 σ.Στην παρούσα διπλωματική εργασία μελετήθηκε το υπάρχον σύστημα καθαριότητας του δήμου κορυδαλλού και σχεδιάστηκαν κάποια προτεινόμενα σενάρια λύσης για την βελτιστοποίηση του, με την ταυτόχρονη ελάχιστη διατάραξη της ήδη υπάρχουσας κατάστασης .Solid waste management in ΚorydallosΓεώργιος Ν. Θεοδωρίδη

Unconventional monetary policies and the macroeconomy: the impact of the UK's QE2 and funding for lending scheme

In this paper we assess the macroeconomic effects of two of the flagship unconventional monetary policies used by the Bank of England during the later stages of the global economic crisis: additional Quantitative Easing (QE) and the introduction of the Funding for Lending Scheme (FLS). We argue that these policies can be seen as complements, as QE effectively bypasses the banks by attempting to reduce risk-free yields directly in order to have a wider effect on asset prices, while FLS operates directly through banks by reducing their funding costs and increasing incentives to lend. We attempt to quantify the effects of these policies by estimating their impact on long-term interest rates and bank funding costs, respectively, and then tracing out their wider effects on the macroeconomy using simulations from a large Bayesian vector autoregression (VAR), which are cross-checked with a simpler Auto-regressive distributed lag (ARDL) approach. We find that the second round of the Bank's QE purchases during 2011-12 and the initial phase of the FLS each boosted GDP in the UK by around 0.5%-0.8%. Their effect on inflation was also broadly positive reaching around 0.6 pp, at its peak

Unconventional monetary policies and the macroeconomy: the impact of the UK's QE2 and funding for lending scheme

In this paper we assess the macroeconomic effects of two of the flagship unconventional monetary policies used by the Bank of England during the later stages of the global economic crisis: additional Quantitative Easing (QE) and the introduction of the Funding for Lending Scheme (FLS). We argue that these policies can be seen as complements, as QE effectively bypasses the banks by attempting to reduce risk-free yields directly in order to have a wider effect on asset prices, while FLS operates directly through banks by reducing their funding costs and increasing incentives to lend. We attempt to quantify the effects of these policies by estimating their impact on long-term interest rates and bank funding costs, respectively, and then tracing out their wider effects on the macroeconomy using simulations from a large Bayesian vector autoregression (VAR), which are cross-checked with a simpler Auto-regressive distributed lag (ARDL) approach. We find that the second round of the Bank's QE purchases during 2011-12 and the initial phase of the FLS each boosted GDP in the UK by around 0.5%-0.8%. Their effect on inflation was also broadly positive reaching around 0.6 pp, at its peak