A New Low Latency Parallel FIR Filter Scheme

A new array type parallel scheme for an FIR digital filter is presented in this paper. The proposed scheme is based on the structure of the carry-save array multiplier where each cell implements the computation of an FIR filter at the bit-level. This structure leads to latency independent of the number of the filter taps. The proposed scheme is pipelined at the bit-level, is systolic at the cell-level and requires less hardware than other schemes based on discrete multipliers.Paraskevas Kalivas received his Diploma and Ph.D. degree in electrical and computer engineering from the National Technical University of Athens, Greece, in 1990 and 2000 respectively.His research interests include computer arithmetic and efficient realization of arithmetic circuits and digital filters.Vassilis Vassilakis received his Diploma in electrical and computer engineering from NationalTechnical University of Athens, Greece, in 1997. He isworking toward the Ph.D. degree in electrical engineering at National Technical University of Athens.His research interests include efficient circuit implemenation of DSP algorithms and java processor architectures.Chris Meletis received his Diploma in electrical and computer engineering from National Technical University of Athens in 1997. Currently, he is working toward the Ph.D. degree in electrical engineering at National Technical University of Athens.His research interests include multirate filter banks, digital filter design and their efficient realization.Kiamal Z. Pekmestzi received his Diploma in electrical engineering from the National Technical University of Athens, Greece, in 1975. From 1975 to 1981, he was a research fellow in the Electronics Department of the Nuclear Research Center Demokritos. He received his Ph.D. in electrical engineering from the University of Patras, Greece, in 1981.From 1983 to 1985, he was a professor at the Higher School of Electronics in Athens. Since 1985, he has been with the National Technical University of Athens, where he is currently a professor. His research interests include computer arithmetic, VLSI digital filters and VLSI design automation.     

Greedy regression ensemble selection: Theory and an application to water quality prediction

This paper studies the greedy ensemble selection family of algorithms for ensembles of regression models. These algorithms search for the globally best subset of regressors by making local greedy decisions for changing the current subset. We abstract the key points of the greedy ensemble selection algorithms and present a general framework, which is applied to an application domain with important social and commercial value: water quality prediction.     

Size fraction characterization of highly-calcareous fly ash

The chemical and mineralogical composition of lignite fly ash (FA) varies as a function of the prevalent conditions in both the processes of power production and lignite mining. The differentiation of the qualitative and quantitative composition of the highly-calcareous lignite fly ash, as a function of its particle size distribution, is verified in this paper. According to the results of the conducted research, a fine-grained fraction of considerable amount presents properties that obstruct the sustainable exploitation of calcareous lignite fly ash in cement industry applications. On the other hand, the same grain fraction (because of its hydraulic properties) can be utilized in other sort of applications, based on different criteria, i.e. in road constructions. The coarse-grained fraction (which reflects a low proportion to the total fly ash output) presents the same undesired characteristics as well. Rather, the intermediate grain fraction (75-150 μm) presents the highly desirable properties when fly ash is utilized as a pozzolanic additive. In addition, the mechanism of the formation of the intermediate grain fraction strongly prevents the factors that cause the variation of fly ash-quality. It is therefore the optimum part of the whole amount of lignite FA, to be utilized as additive in cement manufacturing. The outcomes of this paper will hopefully contribute towards the crucial goal of the expansion of the utilization of calcareous lignite fly ash by proposing a more effective way of using this material, basically by taking advantage of its fundamental chemical and mineralogical properties.     

Applying evolutionary computation to the school timetabling problem: The Greek case

In this contribution, an adaptive algorithm based on evolutionary computation techniques is designed, developed and applied to the timetabling problem of educational organizations. Specifically, the proposed algorithm has been used in order to create feasible and efficient timetables for high schools in Greece. The algorithm has been tested exhaustively with real-world input data coming from many different high schools and has been compared with several other effective techniques in order to demonstrate its efficiency and superior performance. Simulation results showed that the algorithm is able to construct a feasible and very efficient timetable more quickly and easily compared to other techniques, thus preventing disagreements and arguments among teachers and assisting each school to operate with its full resources from the beginning of the academic year. Except from that, due to its inherent adaptive behavior it can be used each time satisfying different specific constraints, in order to lead to timetables, thus meeting the different needs that each school may have.     

Antioxidant and free radical-scavenging activities of phenolic extracts of olive fruits

The antioxidant ability of phenolic extracts of olive fruits during maturity in Chondrolia and Amfissis cultivars grown at 10 m and 300 m altitude showed that altitude affected phenol content, antioxidant and Fe²⁺/Fe³⁺ reduction/binding ability. The hydroxyl radical, peroxyl radical and peroxynitrite-induced DNA nicking assays have been used to evaluate the anti-radical activity of the extracts. Results showed that the ability of olive extracts to prevent radical-mediated DNA damage arises from the triple synergistic action of the genotype, the altitude and the maturation stage.     

A Modeling Study of NH3 Slip Catalysts: Analysis of the SCR/PGM Interactions

We present a simulation study which comparatively analyzes the performances of four configurations of NH₃ slip catalysts (ASC) for automotive NH₃–SCR based Diesel aftertreatment systems. The comparison in terms of NH₃ conversion and N₂ selectivity over a wide range of operating conditions highlights the positive interaction of NH₃–SCR and PGM oxidation chemistries, which is best exploited by a dual-layer configuration with the SCR catalyst on top. This study also emphasizes the key role of modeling and simulation tools in the development of complex exhaust aftertreatment systems as well as the importance of a clear understanding of the catalytic chemistry involved in automotive deNOx converters.     

An ensemble uncertainty aware measure for directed hill climbing ensemble pruning

This paper proposes a new measure for ensemble pruning via directed hill climbing, dubbed Uncertainty Weighted Accuracy (UWA), which takes into account the uncertainty of the decision of the current ensemble. Empirical results on 30 data sets show that using the proposed measure to prune a heterogeneous ensemble leads to significantly better accuracy results compared to state-of-the-art measures and other baseline methods, while keeping only a small fraction of the original models. Besides the evaluation measure, the paper also studies two other parameters of directed hill climbing ensemble pruning methods, the search direction and the evaluation dataset, with interesting conclusions on appropriate values.     

Constant Number Serial Pipeline Multipliers

The pipeline form of the serial/parallel multiplier for constant numbers, which operates without insertion of zero words between successive data, is presented. The constant number is in Canonical Signed Digit (CSD) form and the other factor in two's complement form. The CSD form was chosen because it yields significant hardware reduction. Also, for the above data forms the Lyon's serial pipeline multiplier is examined. For these designs, a special algorithm for the multiplication of two's complement numbers with constant numbers in CSD representation was developed. The proposed serial pipeline multipliers are compared with the existing schemes from the point of hardware complexity.     

Ibotenic acid lesions of the dorsal prefrontal cortex disrupt the expression of behavioral sensitization to cocaine

The present study determined the effect of bilateral lesions of specific cortical or thalamic nuclei that provide excitatory amino acid afferents to the nucleus accumbens (i.e. the dorsal prefrontal cortex, ventral prefrontal cortex, amygdala, hippocampus and periventricular thalamus) on the expression of cocaine-induced behavioral sensitization. Lesions of these nuclei were made during a three-week withdrawal period following repeated daily injections of cocaine or saline. The results indicate that dorsal prefrontal cortex lesions block the expression of behavioral sensitization to cocaine, while ventral prefrontal cortex, fimbria fornix, amygdala and thalamic lesions have no effect. A subsequent microdialysis experiment was performed in order to evaluate the effect of dorsal prefrontal cortex lesions on glutamate transmission in the nucleus accumbens core of cocaine- and saline-pretreated rats. The systemic injection of cocaine produced a significant increase in extracellular glutamate in the nucleus accumbens core among animals with a sham surgery; this effect was blocked by a bilateral lesion of the dorsal prefrontal cortex. Taken together, these results indicate that the dorsal prefrontal cortex, which provides excitatory amino acid input selectively to the core region of the nucleus accumbens, enhances the expression of behavioral sensitization to cocaine by increasing glutamate transmission in this subnucleus.