Fast Simulation of Average Small-Scale Fading for Indoor Localization Applications

The majority of currently available wireless devices’ localization systems are based on received signal strength (RSS) measurements. The input to the localization technique is configured by the average of a number of N instantaneous RSS samples; thereupon, during simulation of such techniques, it is necessary to generate N RSS samples and calculate the corresponding average, which results to increased computational cost and run time. A new technique for reducing computational cost and run time of localization techniques simulators is proposed based on directly sampling a probability distribution function (PDF) corresponding to the average RSS of N samples. However, PDFs of the average RSS cannot be readily calculated and often there is no analytical solution. A study based on goodness-of-fit tests and localization precision is presented herein in order to numerically evaluate the replacement of unknown average RSS PDFs with empirically yielded ones. Furthermore, an indoor propagation and localization techniques simulator has been developed employing the proposed technique. Numerical results demonstrate the applicability of the proposed approach in achieving fast simulation of average small-scale fading and its application to RSS-based localization techniques simulation.     

Reconstruction of serially acquired slices using physics-based modeling

This paper presents an accurate, computationally efficient, fast, and fully automated algorithm for the alignment of two-dimensional (2-D) serially acquired sections forming a 3-D volume. The approach relies on the determination of interslice correspondences. The features used for correspondence are extracted by a 2-D physics-based deformable model parameterizing the object shape. Correspondence affinities and global constrains render the method efficient and reliable. The method accounts for one of the major shortcomings of 2-D slices alignment of a 3-D volume, namely variable and nonuniform thickness of the slices. Moreover, no particular alignment direction is privileged, avoiding global offsets, biases, and error propagation. The method was evaluated on real images and the experimental results demonstrated its accuracy, as reconstruction errors were smaller than I degree in rotation and smaller than 1 pixel in translation.     

A Non-Enumerative Technique for Measuring Path Correlation in Digital Circuits

The correlation between the physical paths of a digital circuit has important implications in various design automation problems, such as timing analysis, test generation and diagnosis. When considering the complexity and tight timing constraints of modern circuits, this correlation affects both the design process and the testing approaches followed in manufacturing. In this work we quantify the diversity of a set of paths (or path segments), let these be critical I/O paths, error propagation paths for various fault models, or paths traced for diagnostic purposes. Circuit paths are encoded using Zero-Suppressed Binary Decision Diagrams (ZBDDs); the proposed method consists of a sequence of standard ZBDD operations to provide a measure of the overlap of the paths under consideration. The main contribution of the presented method is that, path or path segment enumeration is entirely avoided and, hence, a large number of paths can be considered in practical time. Experimentation using standard benchmark circuits demonstrates the effectiveness of the approach in showing the difference in path correlation between various critical I/O path sets as well as propagation paths during test application.     

Synergistic effects of buffer layer processing additives for enhanced hole carrier selectivity in inverted Organic Photovoltaics

Solution based inverted Organic Photovoltaic (OPVs) usually use Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) derivatives combined with pristine processing additives as hole selective contact on top of the hydrophobic conjugated polymer:fullerene active layer. In this study, PEDOT:PSS based hole selective contact is treated with two different boiling point additives, 2,5,8,11-tetramethyl-6-dodecyn-5,8-diol ethoxylate (Dynol) and Zonyl FS-300 fluorosurfactant (Zonyl). Although corresponding inverted OPVs using the above PEDOT:PSS:Additives show similar power conversion efficiency (PCE) values, the mechanisms of their implementation on inverted OPV operation are not identical. By understanding the synergistic effects of PEDOT:PSS processing additives on the hole selectivity of inverted OPVs we demonstrate a novel combination of PEDOT:PSS additives mixture as an effective route to further increase the hole selectivity, reliability andpower conversion efficiency of inverted OPVs.     

A survey on multivariate adaptive control charts: Recent developments and extensions

In the world of business, quality improvement is of high importance for the manufacturing industries. Statistical process control via control charts provides an online monitoring of the product's characteristic. The adaptive feature is being widely used in the design parameters of a control chart, which allows at least one of them to change during the process monitoring. Specifically, a control chart is considered adaptive if at least one of the chart's parameters (sample size, sampling interval, or control limit coefficient) is allowed to change in real time on the basis of the actual values of the sample statistics. In this paper, recent developments in the design of multivariate adaptive control schemes are presented and discussed.     

Mechanical properties of cement-treated mixtures of milled bituminous concrete and crushed aggregates

Milled bituminous concrete and crushed limestone aggregates were combined in the laboratory in various proportions to simulate some of the combinations of materials that can be obtained when the method of mix-in-place recycling with cement is used. The influence of the milled bituminous concrete content of the various mixes is examined in terms of compressive strength (equivalent cubes, uniaxial prism strength), tensile strength (flexural and cylinder splitting strength) and modulus of elasticity (quasi-static, electrodynamic resonance). The effect of these mechanical properties on the traffic and temperature induced stresses as well as on the crack susceptibility of these materials is discussed. It is concluded that the incorporation of milled bituminous concrete in cement-stabilised granular materials imparts interesting properties in these materials, yet further research is needed, including fatigue tests as well as tensile strength and modulus of elasticity determinations at early ages (1–2 days).

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Résumé On a mélangé en laboratoire du béton bitumineux et des granulats calcaires concassés, dans des proportions variées, afin de simuler quelques unes des combinaisons de matériaux qu'on peut obeenir en utilisant la méthode de recyclage sur place par malaxage avec du ciment. On a examiné l'influence de la teneur en béton bitumineux broyé des différents mélanges vis-à-vis de la résistance à la compression (cubes équivalents, résistance uniaxiale du prisme), la résistance à la traction (résistance en flexion et résistance au fendage du cyclindre) et le module élasticité (quasi statique, résonance électro-dynamique). On discute l'effet de ces propriétés mécaniques sur les contraintes génŕées par le trafic et la température, et sur la fissurabilité de ces matériaux. On conclut que l'addition de béton bitumineux broyé à des matériaux granulaires stabilisés par le ciment communique des propriétés intéressantes à ces matériaux mais que, toutefois, une recherche ultérieure doit être conduite, comprenant des essais de fatigue et la détermination de la résistance à la traction et du module d'élasticité aux jeunes ages (1–2 jours).

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Editorial note Dr. Stelios Kolias is a RILEM Senior Member. He is the RILEM Delegate in Greece.     

An Analysis of Computer Center Operation

The operation of a computer center presents an interesting setting for interaction between industrial engineering and computing. Services offered within and outside of the computer should receive, process, and return customers' jobs as rapidly as possible. If the turn-around times for various job types are predictable, the user may utilize this information to decide whether or not to wait at the center to receive his output. Relatively simple models are used to assess the efficiency of various complex computer center operations and the results point to areas where significant service improvements are possible.     

Fiscal Policy Design in Greece in the Aftermath of the Crisis: An Algorithmic Approach

We present a computational approach to the design of fiscal policy that is based on algorithmic, linear feedback control methods. In particular, in the context of a linear, deterministic macro-model, we develop an algorithmic procedure which allows us to design fiscal policy rules for government expenditures so that desired target-levels for GDP are exactly met (that is, complete tracking is achieved). In order to examine the effectiveness of our method we estimate the model for the Greek economy and run some counterfactual policy experiments. These experiments indicate that, for the Greek economy in the beginning of the crisis in early 2010, expansionary fiscal policy would have been able to stimulate growth and reduce the debt-to-GDP ratio.     

Improved performance MRAC of linear and non-linear systems

The problem of improved performance adaptive control (IPAC) of a class of linear and non-linear systems is considered. A method for its solution is presented, the main feature of which lies in augmenting the ‘standard’ model reference adaptive controller by a signal properly designed to compensate for the effect of plant parameter uncertainty on the output error. One of the main performance improvement characteristics of the proposed IPAC is that the zero-state output error can be made arbitrarily small under standard model reference adaptive control (MRAC) assumptions in the case of linear systems, while a similar result holds true for a class of linearizable systems as well. the structure of the proposed controller is such that several existing MRAC results, such as exponential convergence of output and parameter errors in the presence of sufficiently rich reference inputs, remain valid. the proposed controller also achieves improved performance in the presence of a class of bounded disturbances and/or unmodelled dynamics as well as in the case of an adaptation switch-off.