Analytical modelling of hot-spot traffic in deterministically-routed k-ary n-cubes

Many research studies have proposed analytical models to evaluate the performance of k-ary n-cubes with deterministic wormhole routing. Such models however have so far been confined to uniform traffic distributions. There has been hardly any model proposed that deal with non-uniform traffic distributions that could arise due to, for instance, the presence of hot-spots in the network. This paper proposes the first analytical model to predict message latency in k-ary n-cubes with deterministic routing in the presence of hot-spots. The validity of the model is demonstrated by comparing analytical results with those obtained through extensive simulation experiments

THE CONTRIBUTION OF SMALL AND MEDIUM-SIZED ENTERPRISES IN THE ALGERIAN ECONOMY: AN ENTROPY INDEX APPROACH

The role of small and medium enterprises in the economic development of nations cannot be overstated. These businesses, ranging from small family-owned bakeries to medium-sized manufacturing plants, play a vital role in job creation, innovation, and overall economic growth. Numerous studies have established the crucial significance of SMEs to economic success and the development of regions. Our research aims to investigate the extent to which SMEs in Algeria contribute to the country’s economic development and diversification. Considering the economic status of Algeria as a developing nation heavily reliant on oil revenues, it presents a unique case for study. To achieve our research objectives, over 120 official government reports published between 2001 and 2022 are analysed. Descriptive data analysis was conducted, and the Entropy index was calculated to address the problematics and verify the hypotheses. The results reveal that SMEs in Algeria make considerable contributions to employment rates and GDP values. However, their numbers in export operations are very low. The study found that SMEs in Algeria are potent locally, but their performance in global markets is very poor

Modelling of Thin Films Hardness Measured by a Spherical Indenter

In this theoretical contribution, we chose to use an indenter having a spherical geometrical form, which we used to model the surfaces mixture to separate the contributions of substrate and film in the composite covered material hardness. We have considered the coefficients α, β of the model as ratios of the projections of the imprints at the horizontal plans (disks surfaces). We prove that the film hardness of monolayer coating is dependent on the composite and substrate hardness, the geometrical form of the indenter, and the film thickness.В этой теоретической работе рассмотрен индентор сферической геометрической формы, который был использован для составления модели смешанных поверхностей, чтобы оценить вклады подложки и плёнки в твёрдость композитного материала покрытия. Коэффициенты модели α, β рассматриваются как отношения проекций отпечатков на горизонтальные плоскости (в виде дисков). Доказано, что твёрдость плёнки однослойного покрытия зависит от твёрдостей композитного покрытия и подложки, геометрической формы индентора и толщины плёнки.У цій теоретичній роботі розглянуто індентор сферичної геометричної форми, який було використано для складання моделю змішаних поверхонь, щоб оцінити внески підкладинки та плівки у твердість композитного матеріялу покриття. Коефіцієнти моделю α, β розглядаються як співвідношення проєкцій відбитків на горизонтальні площини (у вигляді дисків). Доведено, що твердість плівки одношарового покриття залежить від твердостей композитного покриття та підкладинки, геометричної форми індентора та товщини плівки

Effect of dopamine on synchronous neuronal oscillations in the globus pallidus-subthalamic nucleus network

Changes in the pattern of activity of neurones within the basal ganglia are relevant in the pathophysiology and symptoms of Parkinson’s disease. The globus pallidus (GP) – subthalamic nucleus (STN) network has been proposed to form a pacemaker driving regenerative synchronous bursting activity. In order to test whether this activity can be sustained in vitro a 20o parasagittal slice of mouse midbrain was developed which preserved functional connectivity between the STN and GP. Mouse STN and GP cells were characterised electrophysiologically by the presence or absence of a voltage sag in response to hyperpolarising current steps indicative of Ih and the presence of rebound depolarisations. The presence of evoked and spontaneous post-synaptic GABA and glutamatergic currents indicated functional connectivity between the STN and GP. In control slices, STN cells fired action potentials at a regular rate, activity which was unaffected by bath application of the GABAA receptor antagonist picrotoxin (50 μM) or the glutamate receptor antagonist CNQX (10 μM). Paired extracellular recordings of STN cells showed uncorrelated firing. Oscillatory burst activity was induced pharmacologically using the glutamate receptor agonist, NMDA (20 μM), in combination with the potassium channel blocker apamin (50 -100 nM). The burst activity was unaffected by bath application of picrotoxin or CNQX while paired STN recordings showed uncorrelated activity indicating that the activity is not produced by the neuronal network. Thus, no regenerative activity is evident in this mouse brain preparation, either in control slices or when bursting is pharmacologically induced, suggesting the requirement of other afferent inputs that are not present in the slice. Using single-unit extracellular recording, dopamine (30 μM) produced an excitation of STN cells. This excitation was independent of synaptic transmission and was mimicked by both the Dl-like receptor agonist SKF38393 (10 μM) and the D2-like receptor agonist quinpirole (10 μM). However, the excitation was partially reduced by the D1-like antagonist SCH23390 (2 μM) but not by the D2-like antagonists sulpiride (10 μM) and eticlopride (10 μM). Using whole-recordings, dopamine was shown to induce membrane depolarisation. This depolarisation was caused either by a D1-like receptor mediated increase in a conductance which reversed at -34 mV, consistent with a non-specific cation conductance, or a D2-like receptor mediated decrease in conductance which reversed around -100 mV, consistent with a potassium conductance. Bath application of dopamine altered the pattern of the burst-firing produced by NMDA an apamin towards a more regular pattern. This effect was associated with a decrease in amplitude and ll1crease in frequency of TTX-resistant plateau potentials which underlie the burst activity

Example of Disulfide Conformational Change in the Solid State: Preparation, Optical Properties, and X-ray Studies of a Cystamine-Based Iodoplombate Hybrid

A novel cystamine-based hybrid, namely, α-[NH3(CH2)2SS(CH2)2NH3PbI6]·2H3O (1a), was prepared under solvothermal conditions. Interestingly, 1a, which is built up from isolated PbI6 octahedra, can be easily changed into its polymorph, namely, β-[NH3(CH2)2S–S(CH2)2NH3PbI6]·2H3O (1b) only by heating it up to 45 °C. According to the results of X-ray diffraction analyses, the polymorphic phenomenon of 1a and 1b results from a conformational change in the helical diprotonated cystamine cation in the solid state. Both 1a and 1b crystallized in the orthorhombic Pna21 space group. The reversibility of this transformation is proved by single-crystal X-ray diffraction and second harmonic generation measurements

Tribological study of a bronze obtained by Sintering proceeds

Friction is a widely observed phenomenon requiring scientific capacity in the  tribological behavior of materials. Reliability specialists use language borrowed from the doctors, so they talk about teething, durations of life and death, it is true that the machines as living beings, are born, wear, get tired, suffer defaults and eventually die; That is to say, are reformed, but the comparison stops, because the machines have no nervous system or bloodstream, do not think and feel no pain. Factors that may affect the life, or the factors that affect wear are very numerous: surface characteristics, operating conditions of the lubricant, the atmosphere, and finally the time. In this work we present the effect of speed and load on the tribological characteristics of a Cu 8% Sn bronze pressure sintered self-lubricating mode for two lubricants with different viscosities.Keywords: sintering; powder metallurgy; tribology; lubrication; copper alloy

Considering students’ abilities in the academic advising process

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Academic advising is time-consuming work. At the same time, it needs to be efficient and productive in assisting the students to choose appropriate academic courses towards the completion of their selected programs in a beneficial manner. In addition, both private and public educational institutions are, currently, operating in an extremely competitive market and are, thus, faced with various challenges. Among these are the twin challenges of student retention and the rate of success in completion of their chosen academic courses. The mentioned challenges have a direct bearing on the quality of academic advising and services provided to the students, by the individual academic institution. A number of research studies have been carried out suggesting various online academic advising systems for undergraduate and graduate programs. In this context, we develop and present, here, an academic advising system which differs from and improves upon previously suggested methodologies with the inclusion of the facility to track individual students’ performance and, thus, ability in educational subjects and programs, taken in the previous academic terms. Our suggested methodology is based on the use of this facility to guide students in the selection of courses that they may register for the forthcoming academic term. We believe that the consideration of individual students’ past academic preformation, in our suggested methodology, is a significant improvement and will assist students in making more beneficial choices when registering for academic courses

Performance Evaluation of SDN-WISE in Mobile Wireless Sensors Networks

Wireless Sensors Networks (WSNs) are the backbone of numerous IoT applications such as smart homes, smart cities, smart farming, smart health, and weather monitoring. Software-Defined Networking (SDN) is an emerging communication paradigm that aims to facilitate the management of WSNs and extend their lifetime by shifting the heavy and energy consuming task of routing from sensors to a powerful and unlimited energy server, named the controller. SDN-WISE is a popular SDN implementation for WSNs. This framework has been evaluated and tested in static WSNs where the sensors have fixed positions. However, most IoT applications incorporate mobile nodes such as robots, self-driving cars, and unmanned aerial vehicles, hence the need of evaluating this framework in mobile WSNs. In this paper, we implement mobility scenarios in SDN-WISE. We then conduct an analysis of the performance of SDN-WISE in both static and mobile scenarios. Our simulation results reveal that SDN-WISE achieves a poor performance in mobile WSNs compared to the static counterparts. This stresses the urgent need to develop efficient routing protocols to handle mobility in SDN-WISE

USE OF CALCINATION RESIDUE FROM RICE HUSK AS A SUBSTITUTE FOR CEMENT

In this study, we have developed a new cement composed by a partial substitution of the clinker with artificial pozzolans rich in silica, obtained by treatment of lignocellulosic residues, in this case, ash from rice husk. This substitution is added to the clinker with percentages ranging from 25 to 75%. These substitutions were chosen on the basis of the presence of silica which can react with portlandite (Ca(OH)2). The results obtained show that these materials have, after activation, a great pozzolanicity that allows their addition to the Portland clinker with a percentage of up to 25% of the mass of the clinker. The improvement of this reactivity is achieved by calcinating these additions at temperatures of 750°C. This significantly reduces the CO2 emissions that accompany the production of Portland cement clinker