QoE-Aware Resource Allocation For Crowdsourced Live Streaming: A Machine Learning Approach

In the last decade, empowered by the technological advancements of mobile devices and the revolution of wireless mobile network access, the world has witnessed an explosion in crowdsourced live streaming. Ensuring a stable high-quality playback experience is compulsory to maximize the viewers’ Quality of Experience and the content providers’ profits. This can be achieved by advocating a geo-distributed cloud infrastructure to allocate the multimedia resources as close as possible to viewers, in order to minimize the access delay and video stalls. Additionally, because of the instability of network condition and the heterogeneity of the end-users capabilities, transcoding the original video into multiple bitrates is required. Video transcoding is a computationally expensive process, where generally a single cloud instance needs to be reserved to produce one single video bitrate representation. On demand renting of resources or inadequate resources reservation may cause delay of the video playback or serving the viewers with a lower quality. On the other hand, if resources provisioning is much higher than the required, the extra resources will be wasted. In this thesis, we introduce a prediction-driven resource allocation framework, to maximize the QoE of viewers and minimize the resources allocation cost. First, by exploiting the viewers’ locations available in our unique dataset, we implement a machine learning model to predict the viewers’ number near each geo-distributed cloud site. Second, based on the predicted results that showed to be close to the actual values, we formulate an optimization problem to proactively allocate resources at the viewers’ proximity. Additionally, we will present a trade-off between the video access delay and the cost of resource allocation. Considering the complexity and infeasibility of our offline optimization to respond to the volume of viewing requests in real-time, we further extend our work, by introducing a resources forecasting and reservation framework for geo-distributed cloud sites. First, we formulate an offline optimization problem to allocate transcoding resources at the viewers’ proximity, while creating a tradeoff between the network cost and viewers QoE. Second, based on the optimizer resource allocation decisions on historical live videos, we create our time series datasets containing historical records of the optimal resources needed at each geo-distributed cloud site. Finally, we adopt machine learning to build our distributed time series forecasting models to proactively forecast the exact needed transcoding resources ahead of time at each geo-distributed cloud site. The results showed that the predicted number of transcoding resources needed in each cloud site is close to the optimal number of transcoding resources

Ramadan fasting influences on food intake consumption, sleep schedule, body weight and some plasma parameters in healthy fasting volunteers

This study examines the changes in the lifestyle that accompanied Ramadan fasting. For this purpose, we followed the questionnaire programming meals, food consumption and sleep rhythm. We also followed changes in plasma biological parameters. The results show that daily energy consumption was not changed and neither was the body weight. Nevertheless, a decrease in fat mass was detected. Concerning plasma, we found a decrease in blood glucose from the 7th day of fasting. This effect was found also at the 21st day, accompanied by a reduction in insulin levels. Our results on plasma lipids showed a decrease in triglycerides with total cholesterol level unchanged. Furthermore, we noted an increased HDL-C against a decreased LDL-C fraction. Taken together, these results suggest that fasting may induce beneficial effects in blood lipid concentrations.Keywords: Ramadan fasting, food intake consumption, sleep schedule, body weight, plasma parameters, healthy fasting volunteersAfrican Journal of Biotechnology Vol. 12(21), pp. 3327-333

A Centrifuge Modelling and Finite Element Analysis of Laterally Loaded Single Piles in Sand with Focus on P–Y Curves

Centrifuge modelling and finite element analysis are powerful tools of research on the lateral pile/soil interaction. This paper aims at presenting the main results of experimental and numerical analysis of the pile response under monotonic lateral loading in sand. After description of the experimental devices, it focuses on the determination of the load-transfer P-Y curves for rigid and semi-rigid piles embedded in dry dense sand by using the experimental bending moment profiles obtained in centrifuge tests, as well as by a three-dimensional finite element models using ABAQUS Software. The elastic perfectly plastic Mohr-Coulomb constitutive model has been used to describe the soil response, and the surface-to-surface contact method of ABAQUS software has been used to take into account the nonlinear response at soil/pile interface. The analysis methodology has allowed to propose a hyperbolic function as a model to construct P-Y curves for rigid and semi-rigid piles embedded in dry dense sand, this model is governed by two main parameters, which are the initial subgrade reaction modulus, and the lateral soil resistance, the latter has been formulated in terms of Rankine’s passive earth pressure coefficient, the sand dry unit weight, and the pile diameter

La globalisation des Supply Chains : Quelle place pour le Risk Management ?

International audienceSi la littérature, reconnait la vulnérabilité des Supply Chains Internationales et les risques auxquels elles sont exposées, il est cependant étonnant, de constater le manque de cadres conceptuels et de résultats empiriques qui puissent fournir une compréhension claire du concept de risque et de la gestion des risques dans les supply chains, et dans les relations entre leurs acteurs (Manuj et Mentzer, 2008 ; Zsidisin 2003, Jüttner et al, 2003). Ce papier a pour objectif de faire l‟ébauche d‟un intéressement au Management des risques dans les Supply chains internationales, en permettant de présenter un état de l‟art de la littérature sur la question, tout en étalant les perspectives offertes par une telle discipline dans l‟analyse des Supply Chains Globales

Robust scheduling and robustness measures for the discrete time/cost trade-off problem

Cataloged from PDF version of article.Projects are often subject to various sources of uncertainties that have a negative impact on activity durations and costs. Therefore, it is crucial to develop effective approaches to generate robust project schedules that are less vulnerable to disruptions caused by uncontrollable factors. In this paper, we investigate the robust discrete time/cost trade-off problem, which is a multi-mode project scheduling problem with important practical relevance. We introduce surrogate measures that aim at providing an accurate estimate of the schedule robustness. The pertinence of each proposed measure is assessed through computational experiments. Using the insights revealed by the computational study, we propose a two-stage robust scheduling algorithm. Finally, we provide evidence that the proposed approach can be extended to solve a complex robust problem with tardiness penalties and earliness revenues. 2010 Elsevier B.V. All rights reserved

LA PERTINENCE D'UNE REFLEXION SUR LA RESILIENCE DES SUPPLY CHAINS DANS UN CONTEXTE DE RISQUES: PERSPECTIVES POUR LES SUPPLY CHAINS GLOBALES

International audienceLa supply chain apparaît plus vulnérable et fragile dans un contexte marqué par une grande pression concurrentielle, une demande volatile, une tendance vers les économies d'échelle et l'externalisation. La gestion de risque représente ainsi un enjeu incontournable et essentiel pour la supply chain qui a évolué vers une gestion de réseaux basés sur la valeur. L'objet de ce papier est de faire un état des lieux théorique, sur les concepts de Supply Chain, de risque, de gestion des risques, et de la résilience des Supply Chains. L‟objectif à terme est d‟initier une réflexion sur comment une Supply Chain devient plus résiliente à travers des pratiques de gestion des risques