Robust and Practical Analog-to-Digital Conversion With Exponential Precision

Beta-encoders with error correction were introduced by Daubechies, DeVore, Guumlntuumlrk and Vaishampayan as an alternative to pulse-code modulation (PCM) for analog-to-digital conversion. An N-bit beta-encoder quantizes a real number by computing one of its N-bit truncated beta-expansions where betaisin(1,2) determines the base of expansion. These encoders have (almost) optimal rate-distortion properties like PCM; furthermore, they exploit the redundancy of beta-expansions and thus they are robust with respect to quantizer imperfections. However, these encoders have the shortcoming that the decoder needs to know the value of the base of expansion beta, a gain factor in the circuit used by the encoder, which is an impractical constraint. We present a method to implement beta-encoders so that they are also robust with respect to uncertainties of the value of beta. The method relies upon embedding the value of beta in the encoded bitstream. We show that this can be done without a priori knowledge of beta by the transmitting party. Moreover the algorithm still works if the value of beta changes (slowly) during the implementation     

Equations for heating and cooling of bodies of various shapes

Equations for predicting temperatures in solids of various shapes undergoing heating or cooling are presented. The derived equations are compared with the available numerical values obtained for plates, cylinders and spheres. The centre and surface temperatures and the heat transferred can be described with a maximum deviation of −4.3/3.9%, even though the temperature profiles in these bodies are described with a maximum deviation of −6.8/7.6%.     

Using augmented reality technology in storytelling activities: examining elementary students’ narrative skill and creativity

The aim of the study was to examine the effects of augmented reality technology on stories in terms of narrative skill, story length and creativity and also to examine correlations between these variables. Posttest-only design with a nonequivalent group model was used. In this study, the sample consisted of 100 fifth-grade elementary students, comprising 46 boys and 54 girls. Purposive and convenience sampling methods were applied. For purposive sampling, the group’s ages, education levels, and experiences in storytelling activities were gathered, and for convenience sampling, easy access to schools was considered. As data collection tools, a suitable narrative scale was used which was found in the literature and creative story form was developed by the researcher. According to the findings, mean scores for all variables for the experimental group were higher than those for the control group. Also, a statistically significant mean difference was found between the experimental and control groups with regard to narrative skill, length of stories, and creativity in stories. In fact, a positive correlation was found between all variables. It is important to recognize when a technology is found to contribute positively to narrative skill and creativity in telling stories, and to ensure this technology is used. Determining correlation between these variables may provide a contribution to studies about evaluating the effect of the new technologies.     

Effect of copper on boride layer of boronized ductile cast irons

GGG-50, GGG-60 and GGG-80 ductile cast irons containing 0.01, 0.3 and 0.98 wt% copper, respectively, were boronized in a salt bath and then analyzed using optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Increasing copper concentration in ductile cast irons resulted in formation of mono-phase boride layer (Fe₂B), decreased Si-ferrite zone and hindered the growth discontinuous graphite between boride layer and matrix.     

Planar shape representation and matching under projective transformation

This paper introduces a new representation for planar objects which is invariant to projective transformation. Proposed representation relies on a new shape basis which we refer to as the conic basis. The conic basis takes conic-section coefficients as its dimensions and represents the object as a convex combination of conic-sections. Pairs of conic-sections in this new basis and their projective invariants provides the proposed view invariant representation. We hypothesize that two projectively transformed versions of an object result in the same representation. We show that our hypothesis provides promising recognition performance when we use the nearest neighbor rule to match projectively deformed objects.     

Predictors of attitudinal and behavioral outcomes in mobile advertising: A field experiment

The study examines consumer responses to SMS-based mobile advertising campaigns using a field experiment with actual behavioral responses. Specifically, the effects of message characteristics (i.e., incentives and prior permission) and individual differences of message recipients (i.e., content involvement, prior experience with the mobile medium, and medium-fit perceptions) on the attitudinal and behavioral outcomes of such campaigns are investigated. Perceived intrusiveness of the message and attitude toward the campaign are conceptualized as key attitudinal reactions triggered by a mobile advertising message, which in turn influence the behavioral responses generated by the campaign. Findings suggest that, in comparison to permission and incentive, individual differences are stronger determinants of responses to mobile advertising campaigns. Additionally, intriguing insights with respect to the effectiveness of different types of incentives are provided.     

Failure Analysis of a Location Axle in Tracked Tractor

In this study, a failure analysis was performed on the location axle (brace axle) of a blade on a tracked tractor used in agricultural areas. The analysis included evaluation of the macrostructure of the damage and the microstructure of the material, as well as a chemical analysis of the material. A commercial finite element method software package was used to determine the behavior of the location axle under the defined boundary conditions. After all the examination steps were completed, the main reason for the damage was determined to be manufacture and material error despite the presence of fatigue tracks in the damaged area. In addition, a heat treatment was carried out with the specimens taken from the damaged area and microstructure was re-examined. The experimental and simulation evaluation results provide a technical basis for suggestions to prevent future damage to the location axle.     

Lateral Weir Flow Model using a Curve Fitting Analysis

A numerical approach is considered for flow over side weirs as a substantial part of distribution channels in irrigation systems and treatment units. The model is based on the energy principle and a curve-fitting technique. For this purpose, the side weir was divided into elementary strips to develop generalized equations for discharge and surface profile. The change in water surface elevation towards the weir crest and the inclination of the deflected flow over the weir were also taken into account. Dimensionless parameters were used and the normalized equations solved to obtain the hydraulic parameters of side weirs. The results were plotted to determine general relationships based on the curve-fitting technique. A practical application of the derived equations to obtain hydraulic parameters of side weirs is performed using literature data.     

Dipole moments of styrene/4-vinylpyridine copolymers—II: Relation to microstructure

Mean-square dipole moment values of styrene/4-vinylpyridine (S4VP) copolymers determined at 25–60°C in 1,4-dioxane solutions were related to the microstructure of the chains. Data on the synthesis and dipole moments of S4VP copolymers were used to calculate the distribution of triad fractions and effective dipole moments of styrene, S-centred, and 4-vinylpyridine, V-centred, fractions in the copolymer chains. The relative magnitudes of the effective dipole moment values calculated for each type of triad reflect the effect of dipole–dipole interactions on these values.     

Antioxidant and anticholinesterase evaluation of selected Turkish Salvia species

Since Salvia species (Lamiaceae) have been recorded to be used against memory loss in European folk medicine, we herein examined in vitro anticholinesterase and antioxidant activities of 56 extracts prepared with petroleum ether, chloroform, ethyl acetate and methanol obtained from 14 Salvia species (Salvia albimaculata Hedge and Hub, Salvia aucheri Bentham var. canescens Boiss and Heldr, Salvia candidissima Vahl. ssp. occidentalis, Salvia ceratophylla L., Salvia cryptantha Montbret and Bentham, Salvia cyanescens Boiss and Bal., Salvia frigida Boiss, Salvia forskahlei L., Salvia halophilaHedge, Salvia migrostegia Boiss and Bal., Salvia multicaulis Vahl., Salvia sclarea L., Salvia syriaca L., Salvia verticillata L. ssp. amasiaca) growing in Turkey. The antioxidant activities were assessed by both chemical and enzymatic methods against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging and xanthine/xanthine oxidase (XO) system generated superoxide anion radical inhibition. Anticholinesterase effect of the extracts was tested against both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) at concentrations of 0.2 and 1 mg/ml using a microplate-reader assay based on the Ellman method. Most of the extracts did not show any activity against AChE at 0.2 mg/ml, while the chloroform extracts had noticeable inhibition against BChE between 47.7% and 74.7%. The most active extracts at 1 mg/ml for AChE inhibition were observed to be petroleum ether extract of Salvia albimaculata (89.4%) and chloroform extract of Salvia cyanescens (80.2%), whereas ethyl acetate extracts of Salvia frigida and Salvia migrostegia, chloroform extracts of Salvia candidissima ssp. occidentalis and Salvia ceratophylla, as well as petroleum ether extract of Salvia cyanescens were found to inhibit potently BChE (92.2%, 89.6%, 91.1%, 91.3%, and 91.8%, respectively). Particularly, the ethyl acetate and methanol extracts were observed to be highly active against both DPPH and XO. Our data indicates that nonpolar extracts of Salvia species for anticholinesterase activity and the polar extracts for antioxidant activity are worth further phytochemical evaluation for identifying their active components.