Behavioral-Level Performance and Power Exploration of Data-Intensive Applications Mapped on Programmable Processors

The continuous increase of the computational power of programmable processors has established them as an attractive design alternative, for implementation of the most computationally intensive applications, like video compression. To enforce this trend, designers implementing applications on programmable platforms have to be provided with reliable and in-depth data and instruction analysis that will allow for the early selection of the most appropriate application for a given set of specifications. To address this need, we introduce a new methodology for early and accurate estimation of the number of instructions required for the execution of an application, together with the number of data memory transfers on a programmable processor. The high-level estimation is achieved by a series of mathematical formulas; these describe not only the arithmetic operations of an application, but also its control and addressing operations, if it is executed on a programmable core. The comparative study, which is done using three popular processors (ARM, MIPS, and Pentium), shows the high efficiency and accuracy of the methodology proposed, in terms of the number of executed (micro-)instructions (i.e. performance) and the number of data memory transfers (i.e. memory power consumption). Using the proposed methodology we estimated an average deviation of 23% in our estimated figures compared with the measurements taken from the real execution on the CPUs. This work was supported by the project PENED ’99 ED501 funded by GSRT of the Greek Ministry of Development, and the project PRENED ’99 KE 874 funded by the Research Committee of the Democritus University of Thrace. This work was partially sponsored by a scholarship from the Public Benefit Foundation of Alexander S. Onassis (Minas Dasygenis). Nikolaos Kroupis was born in Trikala in 1976. He receiver the engineering degree and Ms.C. degree in Department of Electrical and Computer Engineering from Democritous University of Thrace, Greece, in 2000 and 2002, respectively. Since 2002 he has been a Ph.D. student at the Laboratory of Electrical and Electronic Materials Technology. His research interests are in software/hardware co-design of embedded system for signal processing applications. Nikos D. Zervas received a Diploma in Electrical & Computer Engineering from University of Patras, Greece in 1997. He received the Ph.D. degree in the Department of Electrical and Computer Engineering of the same University in 2004. His research interests are in the area of high-level, power optimization techniques and methodologies for multimedia and telecommunication applications. He has received an award from IEEE Computer Society in the context of Low-Power Design Contest of 2000 IEEE Computer Elements Mesa Workshop. Mr. Zervas is a member of the IEEE, ACM and of the Technical Chamber of Greece. Minas Dasygenis was born in Thessaloniki in 1976. He received his Diploma in Electrical and Computer Engineering in 1999, from the Democritus University of Thrace, Greece, and for his diploma Thesis he was honored by The Technical Chamber of Greece and Ericsson Hellas. In 2005, he received his PhD Degree from the Democritus University of Thrace. His research interests include low-power VLSI design of arithmetic circuits, residue number system, embedded architectures, DSPs, hardware/ software codesign and IT security. He has published more than 20 papers in international journals and conferences and he has been a principal researcher in three European research projects. Konstantinos Tatas received his degree in Electrical and Computer Engineering from the Democritus University of Thrace, Greece in 1999. He received his Ph.D. in the VLSI Design and Testing Center in the same University by June 2005. He has been employed as an RTL designer in INTRACOM SA, Greece between 2000 and 2003. His research interests include low-power VLSI design of DSP and multimedia systems, computer arithmetic, IP core design and design for reuse. Antonios Argyriou received the degree in Electrical and Computer engineering from the Democritous University of Thrace, Greece, in 2001, and the M.S. and Ph.D. degrees in Electrical and Computer engineering from the Georgia Institute of Technology, Atlanta, in 2003 and 2005, respectively. His primary research interests include wireless networks, mobile computing and multimedia communications. He is a member of the IEEE and ACM. Dimitrios Soudris received his Diploma in Electrical Engineering from the University of Patras, Greece, in 1987. He received the Ph.D. Degree in Electrical Engineering, from the University of Patras in 1992. He is currently working as Ass. Professor in Dept. of Electrical and Computer Engineering, Democritus University of Thrace, Greece. His research interests include low power design, parallel architectures, embedded systems design, and VLSI signal processing. He has published more than 140 papers in international journals and conferences. He was leader and principal investigator in numerous research projects funded from the Greek Government and Industry as well as the European Commission (ESPRIT II-III-IV and 5th and 6th IST). He has served as General Chair and Program Chair for the International Workshop on Power and Timing Modelling, Optimisation, and Simulation (PATMOS). He received an award from INTEL and IBM for the project results of LPGD #25256 (ESPRIT IV). He is a member of the IEEE, the VLSI Systems and Applications Technical Committee of IEEE CAS and the ACM. Antonios Thanailakis was born in Greece on August 5, 1940. He received B.Sc. degrees in physics and electrical engineering from the University of Thessaloniki, Greece, 1964 and 1968, respectively, and the Msc. and Ph.D. Degrees in electrical engineering and electronics from UMIST, Manchester, U.K. in 1968 and 1971, respectively. He has been a Professor of Microelectronics in Dept. of Electrical and Computer Eng., Democritus Univ. of Thrace, Xanthi, Greece, since 1977. He has been active in electronic device and VLSI system design research since 1968. His current research activities include microelectronic devices and VLSI systems design. He has published a great number of scientific and technical papers, as well as five textbooks. He was leader for carrying out research and development projects funded by Greece, EU, or other organizations on various topics of Microlectronics and VLSI Systems Design (e.g. NATO, ESPRIT, ACTS, STRIDE).     

Wideband numerical modelling and performance optimisation of arbitrarily-shaped anechoic chambers via an unconditionally stable time-domain technique

A 3-D curvilinear alternating-direction implicit finite-difference time-domain (ADI-FDTD) algorithm for the broadband analysis and optimised design of anechoic and semi-anechoic chambers with arbitrary shape is presented in this paper. The unconditionally stable and frequency-dependent method develops a new family of spatial/temporal forms which reduce the critical dispersion errors of existing approaches and allow the precise performance evaluation of essential components or dissimilar lossy absorbers before their actual construction. Hence, the proposed technique circumvents prolonged simulations via temporal increments significantly beyond the Courant limit and achieves substantial accuracy even for highly curved details. Numerical results, concerning several realistic structures as well as comparisons with measured data obtained according to specific international EMC standards, demonstrate the preceding advantages and lead to optimal chamber configurations.This work has been supported by the State Scholarships Foundation of Greece (I.K.Y. – Athens, Greece) under Postdoctoral Research Scholarship No. 475/2003–2004.     

The study and performance of a modified conventional refrigerator to serve as a PV powered one

This paper describes the design and development stages to convert a conventional refrigerator to a solar powered one. The development of such a system was effected and the results of this work to provide a cost effective version are given.A conventional refrigerator was chosen and some changes were introduced to reduce the cooling load and consequently the power required. Tests were carried out to study the performance of the refrigerator components and especially the compressor's, as well as the refrigerator as a whole. The latter tests are the well-known pull down tests.The cost effective final product was searched via a PV sizing package developed for the purpose of this project incorporating the LCC analysis.     

Motion-based segmentation of objects using overlapping temporal windows

Motion segmentation refers to the problem of separating the objects in a video sequence according to their motion. It is a fundamental problem of computer vision, since various systems focusing on the analysis of dynamic scenes include motion segmentation algorithms. In this paper we present a novel approach, where a video shot is temporally divided in successive and overlapping windows and motion segmentation is performed on each window respectively. This attribute renders the algorithm suitable even for long video sequences. In the last stage of the algorithm the segmentation results for every window are aggregated into a final segmentation. The presented algorithm can handle effectively asynchronous trajectories on each window even when they have no temporal intersection. The evaluation of the proposed algorithm on the Berkeley motion segmentation benchmark demonstrates its scalability and accuracy compared to the state of the art.     

Optimal Placement of Phasor Measurement Units with Linear and Non-linear Models

Abstract—This article presents a non-linear programming-based model for the optimal placement of phasor measurement units. The optimal phasor measurement units placement is formulated to minimize the number of phasor measurement units required for full system observability and to maximize the measurement redundancy at all buses in a power system. A sequential quadratic programming algorithm is used for the solution of the proposed model. The existence of power flow and injection measurements, the limited phasor measurement units channel capacity, the lack of communication facilities in substations, and the single phasor measurement units loss are also incorporated into the initial proposed formulation. The non-linear programming model is applied to IEEE 14- and 118-bus test systems in MATLAB. The accuracy and the effectiveness of the proposed method is verified by comparing the simulation results to those obtained by a binary integer programming model also implemented in MATLAB. The comparative study shows that the proposed non-linear programming model yields the same number of phasor measurement units as the binary integer programming model. A remarkable advantage of the non-linear programming against binary integer linear programming is its capability to give more than one optimal solution, each one having the same minimum number of phasor measurement units (same minimum objective value), but at different locations.     

An adaptive design for quantized feedback control of uncertain switched linear systems

This paper addresses the problem of asymptotic tracking for switched linear systems with parametric uncertainties and dwell‐time switching, when input measurements are quantized due to the presence of a communication network closing the control loop. The problem is solved via a dynamic quantizer with dynamic offset that, embedded in a model reference adaptive control framework, allows the design of the adaptive adjustments for the control parameters and for the dynamic range and dynamic offset of the quantizer. The overall design is carried out via a Lyapunov‐based zooming procedure, whose main feature is overcoming the need for zooming out at every switching instant, in order to compensate for the possible increment of the Lyapunov function at the switching instants. It is proven analytically that the resulting adjustments guarantee asymptotic state tracking. The proposed quantized adaptive control is applied to the piecewise linear model of the NASA Generic Transport Model aircraft linearized at multiple operating points.     

A higher-order unsplit-field perfectly matched layer for the reflectionless truncation of 3-D spherical FDTD lattices

An enhanced higher-order finite-difference time-domain (FDTD) method for the systematic implementation of 3-D reflectionless perfectly matched layers (PML) in spherical coordinates is presented. By establishing a topologically unsplit-field formulation, the novel technique introduces accurate nonstandard schemes that eliminate the notably intricate lattice dispersion errors. Moreover, the wider spatial increments are treated via self-adaptive compact operators, while a mesh expansion process yields a significant reduction of the absorber's depth. For the temporal variable, the proposed method employs a multistage leapfrog integration that guarantees stability and excitation universality. Hence, because of the optimal configuration of the new PML, it attains a critical annihilation of both propagating and spurious wave families, even for complicated domains. Numerical investigation verifies the superiority of the higher-order algorithm via several unbounded radiation and scattering spherical problems.     

Fault detection and identification for a class of continuous piecewise affine systems with unknown subsystems and partitions

This paper establishes a novel online fault detection and identification strategy for a class of continuous piecewise affine (PWA) systems, namely, bimodal and trimodal PWA systems. The main contributions with respect to the state‐of‐the‐art are the recursive nature of the proposed scheme and the consideration of parametric uncertainties in both partitions and in subsystems parameters. In order to handle this situation, we recast the continuous PWA into its max‐form representation and we exploit the recursive Newton‐Gauss algorithm on a suitable cost function to derive the adaptive laws to estimate online the unknown subsystem parameters, the partitions, and the loss in control authority for the PWA model. The effectiveness of the proposed methodology is verified via simulations applied to the benchmark example of a wheeled mobile robot.     

Substrate constructed by an array of split ring resonators for a THz planar antenna

Metamaterials are artificial materials offering unique properties which render them useful for various applications. In the present paper, we examine whether it is possible to design a split ring resonators’ (SRRs) based metamaterial substrate for enhancing the performance of planar antennas operating at THz frequencies. Initially, the radiating characteristics of a simple rectangular patch antenna over two well-known SRR substrates are studied. The yielded results are then compared to those of two novel designs of metamaterial antenna substrate with SRRs of decreasing size which are proposed to improve the antenna’s performance.     

Evaluating content quality and helpfulness of online product reviews: The interplay of review helpfulness vs. review content

Online reviews have received much attention recently in the literature, as their visibility has been proven to play an important role during the purchase process. Furthermore, recent theoretical insight argue that the votes casted on how helpful an online review is (review helpfulness) are of particular importance, since they constitute a focal point for examining consumer decision making during the purchase process. In this paper, we explore the interplay between online review helpfulness, rating score and the qualitative characteristics of the review text as measured by readability tests. We construct a theoretical model based on three elements: conformity, understandability and expressiveness and we investigate the directional relationship between the qualitative characteristics of the review text, review helpfulness and the impact of review helpfulness on the review score. Furthermore, we examine whether this relation holds for extreme and moderate review scores. To validate this model we applied four basic readability measures to a dataset containing 37,221 reviews collected from Amazon UK, in order to determine the relationship between the percentage of helpful votes awarded to a review and the review text’s stylistic elements. We also investigated the interrelationships between extremely helpful and unhelpful reviews, as well as absolutely positive and negative reviews using intergroup comparisons. We found that review readability had a greater effect on the helpfulness ratio of a review than its length; in addition, extremely helpful reviews received a higher score than those considered less helpful. The present study contributes to the ever growing literature on on-line reviews by showing that readability tests demonstrate a directional relationship with average length reviews and their helpfulness and that this relationship holds both for moderate and extreme review scores.