Performance analysis of energy detection over hyper-Rayleigh fading channels

This study investigates the performance of energy detection (ED)-based spectrum sensing over two-wave with diffused power (TWDP) fading channels, which have been found to provide accurate characterisation for a variety of fading conditions. A closed-form expression for the average detection probability of ED-based spectrum sensing over TWDP fading channels is derived. This expression is then used to describe the behaviour of ED-based spectrum sensing for a variety of channels that include Rayleigh, Rician and hyper-Rayleigh fading models. Such fading scenarios present a reliable behavioural model of machine-to-machine wireless nodes operating in confined structures such as in-vehicular environments

An investigation into the effect of rate of stirring of bath electrolyte on the properties of electrodeposited CdTe thin film semiconductors

Electrodeposition (ED) has been recognized as a low cost and scalable technique available for fabrication of CdS/CdTe solar cells. Photovoltaic activity of these electrodeposited semiconductor materials drastically depends on the ED growth parameters namely; electrodeposition potential, concentrations and ratios of concentrations of precursors used to prepare the bath electrolyte, pH of the electrolyte, deposition temperature and rate of stirring of the electrolyte. In order to grow thin films with good photovoltaic properties, it is essential to maintain these variables at their optimum ranges of values during electrodepositions. Hence, this study was conducted to investigate the dependence of the properties of electrodeposited CdTe thin film material on the rate of stirring of the bath electrolyte. The CdTe material was grown on glass/FTO (23 cm2) and glass/FTO/CdS (23 cm2) surfaces in bath electrolytes containing 1.0 mol/L CdSO4 and 1.0 mmol/L TeO2 solutions at different rates of stirring within the range of 0-350 rpm while keeping the values of pH of the electrolyte, deposition temperature and cathodic deposition potential with respect to the saturated calomel electrode at 2.3, 65 °C and 650 mV respectively. After the heat treatment at 400 °C in air atmosphere, the deposited samples with a good visual appearance were selected and evaluated based on their morphological, elemental, structural, optical and electrical properties in order to identify the optimum range of rate of stirring for electrodeposition of CdTe thin film semiconductors. Results revealed that, rates of stirring in the range of 60-85 rpm in a 100 mL volume of electrolyte containing the substrate and the counter electrodes in the center of the bath with a separation of 2.0 cm between them can electrodeposit CdTe layers exhibiting required levels of morphological, structural, optical and electrical properties on both glass/FTO and glass/FTO/CdS surfaces

EFFECT OF GRAZING ON SOME PHYSIOLOGICAL PROPERTIES IN INTEGRATED FARMING SOILS.

The objective of this study was to investigate the effect of grazing on somesoil properties; bulk density (BD), true density, porosity, moisture content(Me) and pH. The effect of long term grazing (>20 yrs) was examined in acoconut - pasture - cattle integrated farming system in Kamburupitiya area.Short term grazing effect was compared with an adjoining coconut plantationpermitting 18 buffaloes to graze for 6 months. Another adjoining ungrazedcoconut farm soil was considered as control. Soil samples were taken fromthe topsoil using a core sampler (v = 98.21 em"). Four replicate samples weretaken three times with 30 days interval and analyzed in triplicates. Data werestatistically analyzed using SAS.Soils collected from the long term integrated farming site had a significantlyhigher (p < 0.05) average pH (5.58) than that of non-integrated sites (4.65).Reduction of acidity may be due to the improvement of soil nutrients viadung, urine and accumulation of litter. It was observed that the soil inintegrated sites were comparatively dark in color. BD of integrated soil(1.15g/cm3) was significantly lower than that of non-integeated soil (21.26%)due to the better ground cover by dominant prostate type herbages comparedto ungrazed soils where erect type herbages were prominent. Soil porosityalso improved due to integration (47.76%) with that of non-integrated soil(43.76%). There was no significant difference observed under the effect ofshort term grazing. A considerable time period may be required to change toimproved soil properties.It is concluded that long term crop-livestock integration could improve thesoil physiochemical properties

EFFECT OF BUFFALO GRAZING ON PLANT SPECIES DIVERSITY IN A COCONUT-PASTURE-CATTLE INTEGRATED SYSTEM

The effects of long and short-term buffalo grazing on plant species diversityunder coconut were examined. 18 Murrah and Surthi pure and crossbredbuffaloes were allowed to graze 3 hours a month for 6 months (short termgrazing). Herbage from an adjoining coconut plantation was taken as thecontrol. Quadrate sampling was adopted to analyze herbage up to specieslevel and four random samples were taken at each event.The Shannon diversity Index (H), species richness and evenness werecalculated for each treatment.Results showed that the diversity index and evenness in the undisturbedhabitat (ungrazed coconut plantation) were 2.176 and 0.6679 respectively andwere much higher than highly disturbed habitat (grazed plantation) where thesame values were 0.4.747 and 0.2160. The short term grazing effect showedan intermediate results. In the ungrazed site there were greater number ofplant species and more equitable the individuals in the community weredistributed. Long term grazed coconut plantation had only 9 species and over80% of the individuals belong to one species; Carpet grass (Axonopus affinis)the most common species in a grazing land. Grazing pressure was favorableto dominate prostate type plants. It was shown that grazing pressure whethershort term or long term changed the abundance of plant species.It is concluded that different levels of disturbance have different effects onplant species diversity

Behaviour of cattle in an agro-forestry system

Objective of the present study was to understand the behaviour of dairy cattle tethered underagro-forcstry systems. Three genetically uncharacterized, indigenous, non-lactating cows and twobulls (mean live weight 199±29) were tethered close to a water stream in an agro-forestry system.The vegetation of the agro-forestry system comprised of teak, coconut, mahogany and shrubs. Animalshad enough foraging materials around the place they were tethered. One observer was assigned toeach animal. The behaviour of the animals was observed for five hours from 1000 1500 hrs. Themean temperature and the relative humidity of day of the study were 28°C and 79% respectively.Frequency and the duration of the time spent on nine behaviours were recorded. The behaviouralactivities studied were drinking, feeding (ground level and upper level), lying, standing, walking,urination, defecation, vocal ization and interactions (cattle-cattle and cattle-other an irnals ). Feedingwas the most prominent behaviour of the animals. The time spent on feeding and the frequency offeeding during the 300 minutes study period were 252 min and 23, respectively and thus the feedingbehaviour accounted for 84% of the total time budget. The frequency (15) and the time spent onground level grazing (234 min) were significantly higher (p<O.OOI) than the frequencies and the timespent on upper level feeding. Though not statistically significant, animals spent more time on standing(18.9min or 6.3% of the total time) than on Laying (14.6 min or 5% of the total time). The frequencyof standing (5) was also significantly (p<O.OO I) higher than that oflying (I). May be due to tethering,cattle spent less time (8.3 minutes or 2.7% of the total time) on walking. The frequency of drinking(2) and the time spent on drinking were (3 min or 1% of the total time) unexpectedly low. Cattledefecated and urinated twice during the five- hour study period. Vocalization was the least prominentbehavioural activity. It is concluded that cattle highly engage with feeding particularly, on groundlevel when they are tethered under agro-forestry systems. Further researches are needed to determineas to why the drinking behaviour is suppressed when tethered in agro-forestry systems

Behaviour of cattle in an agro-forestry system

Objective of the present study was to understand the behaviour of dairy cattle tethered underagro-forcstry systems. Three genetically uncharacterized, indigenous, non-lactating cows and twobulls (mean live weight 199±29) were tethered close to a water stream in an agro-forestry system.The vegetation of the agro-forestry system comprised of teak, coconut, mahogany and shrubs. Animalshad enough foraging materials around the place they were tethered. One observer was assigned toeach animal. The behaviour of the animals was observed for five hours from 1000 1500 hrs. Themean temperature and the relative humidity of day of the study were 28°C and 79% respectively.Frequency and the duration of the time spent on nine behaviours were recorded. The behaviouralactivities studied were drinking, feeding (ground level and upper level), lying, standing, walking,urination, defecation, vocal ization and interactions (cattle-cattle and cattle-other an irnals ). Feedingwas the most prominent behaviour of the animals. The time spent on feeding and the frequency offeeding during the 300 minutes study period were 252 min and 23, respectively and thus the feedingbehaviour accounted for 84% of the total time budget. The frequency (15) and the time spent onground level grazing (234 min) were significantly higher (p<O.OOI) than the frequencies and the timespent on upper level feeding. Though not statistically significant, animals spent more time on standing(18.9min or 6.3% of the total time) than on Laying (14.6 min or 5% of the total time). The frequencyof standing (5) was also significantly (p<O.OO I) higher than that oflying (I). May be due to tethering,cattle spent less time (8.3 minutes or 2.7% of the total time) on walking. The frequency of drinking(2) and the time spent on drinking were (3 min or 1% of the total time) unexpectedly low. Cattledefecated and urinated twice during the five- hour study period. Vocalization was the least prominentbehavioural activity. It is concluded that cattle highly engage with feeding particularly, on groundlevel when they are tethered under agro-forestry systems. Further researches are needed to determineas to why the drinking behaviour is suppressed when tethered in agro-forestry systems

Characterizing Comment Types and Levels of Engagement in Video-Based Learning as a Basis for Adaptive Nudging

Video is frequently used as a learning medium in a variety of educational settings, including large online courses as well as informal learning scenarios. To foster learner engagement around instructional videos, our learning scenario facilitates interactive note taking and commenting similar to popular social video-sharing platforms. This approach has recently been enriched by introducing nudging mechanisms, which raises questions about ensuing learning effects. To better understand the nature of these effects, we take a closer look at the content of the comments. Our study is based on an ex post analysis of a larger data set from a recent study. As a first step of analysis, video comments are clustered based on a feature set that captures the temporal and semantic alignment of comments with the videos. Based on the ensuing typology of comments, learners are characterized through the types of comments that they have contributed. The results will allow for a better targeting of nudges to improve video-based learning

Log-moment estimators of the Nakagami-lognormal distribution

[EN] In this paper, estimators of the Nakagami-lognormal (NL) distribution based on the method of log-moments have been derived and thoroughly analyzed. Unlike maximum likelihood (ML) estimators, the log-moment estimators of the NL distribution are obtained using straightforward equations with a unique solution. Also, their performance has been evaluated using the sample mean, confidence regions and normalized mean square error (NMSE). The NL distribution has been extensively used to model composite small-scale fading and shadowing in wireless communication channels. This distribution is of interest in scenarios where the small-scale fading and the shadowing processes cannot be easily separated such as the vehicular environment.This work has been funded in part by the Programa de Estancias de Movilidad de Profesores e Investigadores en Centros Extranjeros de Ensenanza Superior e Investigacion of the Ministerio de Educacion, Cultura y Deporte, Spain, PR2015-00151 and by the Ministerio de Economia, Industria y Competitividad of the Spanish Government under the national project TEC2017-86779-C2-2-R, through the Agencia Estatal de Investigacion (AEI) and the Fondo Europeo de Desarrollo Regional (FEDER).Reig, J.; Brennan, C.; Rodrigo Peñarrocha, VM.; Rubio Arjona, L. (2019). Log-moment estimators of the Nakagami-lognormal distribution. EURASIP Journal on Wireless Communications and Networking. 1-10. https://doi.org/10.1186/s13638-018-1328-6S110J. M. Ho, G. L. Stüber, in Co-channel interference of microcellular systems on shadowed Nakagami fading channels. Proc. IEEE 43rd Vehicular Technology Conference, 1993 (VTC 93) (IEEESecaucus, 1993), pp. 568–571.A. A. Abu-Dayya, N. C. Beaulieu, Micro- and macrodiversity NCFSK (DPSK) on shadowed Nakagami-fading channels. IEEE Trans. Commun.42(9), 2693–2702 (1994).X. Wang, W. Wang, Z. Bu, Fade statistics for selection diversity in Nakagami-lognormal fading channels. Electron. Lett.42(18), 1046–1047 (2006).D. T. Nguyen, Q. T. Nguyen, S. C. Lam, Analysis and simulation of MRC diversity reception in correlated composite Nakagami-lognormal fading channels. REV J. Electron. Commun.4(1–2), 44–51 (2014).P. Xu, X. Zhou, D. Hu, in Performance evaluations of adaptive modulation over composite Nakagami-lognormal fading channels. 2009 15th Asia-Pacific Conference on Communications (IEEEShanghai, 2009), pp. 467–470.G. C. Alexandropoulos, A. Conti, P. T. Mathiopoulos, in Adaptive M-QAM systems with diversity in correlated Nakagami-m fading and shadowing. IEEE Global Telecommunications Conference (GLOBECOM 2010) (IEEEMiami, 2010), pp. 1–5.Ö. Bulakci, A. B. Saleh, J. Hämäläinen, S. Redana, Performance analysis of relay site planning over composite fading/shadowing channels with cochannel interference. IEEE Trans. Veh. Technol.62(4), 1692–1706 (2013).W. Cheng, Y. Huang, On the performance of adaptive SC/MRC cooperative systems over composite fading channels. Chin. J. Electron.25(3), 533–540 (2016).M. G. Kibria, G. P. Villardi, W. Liao, K. Nguyen, K. Ishizu, F. Kojima, Outage analysis of offloading in heterogeneous networks: Composite fading channels. IEEE Trans. Veh. Technol.66(10), 8990–9004 (2017).K. Cho, J. Lee, C. G. Kang, Stochastic geometry-based coverage and rate analysis under Nakagami & log-normal composite fading channel for downlink cellular networks. IEEE Commun. Lett.21(6), 1437–1440 (2017).R. Singh, M. Rawat, Closed-form distribution and analysis of a combined Nakagami-lognormal shadowing and unshadowing fading channel. J Telecommun. Inf. Technol.4:, 81–87 (2016).J. Reig, L. Rubio, Estimation of the composite fast fading and shadowing distribution using the log-moments in wireless communications. IEEE Trans. Wireless. Commun.12(8), 3672–3681 (2013).S. Atapattu, C. Tellambura, H. Jiang, A mixture gamma distribution to model the SNR of wireless channels. IEEE Trans. Wireless Commun.10(12), 4193–4203 (2011).Q. Wang, H. Lin, P. Kam, Tight bounds and invertible average error probability expressions over composite fading channels. J. Commun. Netw.18(2), 182–189 (2016).J. M. Holtzmann, On using perturbation analysis to do sensitivity analysis: derivatives versus differences. IEEE Trans. Autom. Control. 37(2), 243–247 (1992).H. Suzuki, A statistical model for urban radio propagation. IEEE Trans. Commun.25(7), 673–680 (1977).M. D. Yacoub, The α- μ distribution: a physical fading model for the Stacy distribution. IEEE Trans. Veh. Technol.56(1), 122–124 (2007).P. M. Shankar, Error rates in generalized shadowed fading channels. Wirel. Pers. Commun.28(3), 233–238 (2004).J. -M. Nicolas, Introduction aux statistiques de deuxième espèce: applications des logs-moments et des logs-cumulants à l’analyse des lois d’images radar. Traitement du Signal. 19(3), 139–167 (2002). Translation to English by S. N. Anfinsen.C. Withers, S. Nadarajah, A generalized Suzuki distribution. Wirel. Pers. Commun.62(4), 807–830 (2012).M. Abramowitz, Handbook of Mathematical Functions, with Formulas, Graphs, and Mathematical Tables, 9th edn. (Dover, New York, NY, 1972).M. K. Simon, M. S. Alouini, Digital Communication over Fading Channels, 2nd edn. (Wiley, Hoboken, NY, 2005).Z. Sun, J. Du, in Proc. 10th International Conference, ICIC 2014, ed. by D. -S. Huang, V. Bevilacqua, and P. Premaratne. Log-cumulant parameter estimator of log-normal distribution. Intelligent computing theory (SpringerNew York, NY, 2014), pp. 668–674.S. Zhang, J. M. Jin, Computation of Special Functions (Wiley, New York, 1996).G. Casella, R. L. Berger, Statistical Inference (Duxbury Thomson Learning, Pacific Grove, CA, 2002).C. Kleiber, S. Kotz, Statistical Size Distributions in Economics and Actuarial Sciences (Wiley, Hoboken, NJ, 2003).L. Devroye, Non-uniform Random Variate Generation (Springer, New York,1986).A. Abdi, M. Kaveh, Performance comparison of three different estimators for the Nakagami m parameter using Monte Carlo simulation. IEEE Commun. Lett.4(4), 119–121 (2000).L. Rubio, J. Reig, N. Cardona, Evaluation of Nakagami fading behaviour based on measurements in urban scenarios. Int. J. Electron. Commun. (AEÜ). 61(2), 135–138 (2007)