Recycling cellular downlink energy for overlay self-sustainable IoT networks

This paper investigates the self-sustainability of an overlay Internet of Things (IoT) network that relies on harvest- ing energy from a downlink cellular network. Using stochastic geometry and queueing theory, we develop a spatiotemporal model to derive the steady state distribution of the number of packets in the bu ff ers and energy levels in the batteries of IoT devices given that the IoT and cellular communications are allocated disjoint spectrum. Particularly, each IoT device is modeled via a two-dimensional discrete-time Markov Chain (DTMC) that jointly tracks the evolution of data bu ff er and energy battery. In this context, stochastic geometry is used to derive the energy generation at the batteries and the packet transmission probability from bu ff ers taking into account the mutual interference from other active IoT devices. To this end, we show the Pareto-Frontiers of the sustainability region, which defines the network parameters that ensure stable network operation and finite packet delay. The results provide several insights to design self-sustainable IoT networks. Index Terms —Spatiotemporal models, stochastic geometry, queuing theory, energy harvesting, packet transmission success probability, two-dimensional discrete-time Markov chain, sta- bility conditions

A discriminating microscopy technique for the measurement of ice crystals and air bubbles size distribution in sorbets

24ième Congrès International du Froid ICR 2015, Yokohama, JPN, 16-/08/2015 - 22/08/2015International audienceIn this work, a technique capable to distinguish between ice crystals and air bubbles in sorbets was developed in order to characterize the effect of operating conditions on their size distributions at the exit of the freezer. A pilot freezer was used to crystallize and aerate a commercial lemon sorbet mix. Crystals and bubbles sizes were measured using a light microscope technique under low temperature in a refrigerated glove box developed in the lab for that purpose. Results showed that the developed microscope technique allowed to distinguish them and to quantify their size distributions. Measurements showed that ice crystals size decreases with air flow rate while air bubbles size increases. The latter also increases with the cylinder pressure inside the scraped surface heat exchanger (SSHE)

TAT-Mediated Transduction of MafA Protein In Utero Results in Enhanced Pancreatic Insulin Expression and Changes in Islet Morphology

Alongside Pdx1 and Beta2/NeuroD, the transcription factor MafA has been shown to be instrumental in the maintenance of the beta cell phenotype. Indeed, a combination of MafA, Pdx1 and Ngn3 (an upstream regulator of Beta2/NeuroD) was recently reported to lead to the effective reprogramming of acinar cells into insulin-producing beta cells. These experiments set the stage for the development of new strategies to address the impairment of glycemic control in diabetic patients. However, the clinical applicability of reprogramming in this context is deemed to be poor due to the need to use viral vehicles for the delivery of the above factors. Here we describe a recombinant transducible version of the MafA protein (TAT-MafA) that penetrates across cell membranes with an efficiency of 100% and binds to the insulin promoter in vitro. When injected in utero into living mouse embryos, TAT-MafA significantly up-regulates target genes and induces enhanced insulin production as well as cytoarchitectural changes consistent with faster islet maturation. As the latest addition to our armamentarium of transducible proteins (which already includes Pdx1 and Ngn3), the purification and characterization of a functional TAT-MafA protein opens the door to prospective therapeutic uses that circumvent the use of viral delivery. To our knowledge, this is also the first report on the use of protein transduction in utero

Approche multi-échelles de la congélation des produits alimentaires

Abstract : Freezing is used to increase the shelf life of foods thanks to the lowering of the temperature which reduces the kinetics of the reactions of degradation but also thanks to the solidification of water which reduces its availability for the development of microorganisms. But freezing can also be used to transform and create a desired texture in the case of products that are initially in liquid state and are consumed at frozen state, such as frozen desserts. For these foods, the problem of freezing is different since the crystals are part of the structure of the final product.My research is dedicated to the understanding of the interactions occurring at different scales between strongly coupled phenomena (heat, mass transfer and flow) during the freezing of foods. This work has been carried out since 2002 as a lecturer at AgroParistech within the UMR SayFood and within the FRISE unit. At the beginning, focused on the freezing of semi-liquid foods under shear, my work has gradually expanded to the freezing of non porous and porous solid foods.The developed approach combines laboratory and semi-industrial pilot scale experiments with modelling. The dynamics of food structuring are monitored over time thanks to the development of advanced tools allowing characterization at different scales. The phenomena are studied using a reasoned simplification approach of the studied product and/or of the developed model.The prospects of this research are to make the link between the scales : the one the food subjected to negative cold and that of its microstructure. First by the systematic experimental monitoring of markers at these scales. Then by using modelling tools to move from one scale to another. This approach will be used to deepen the understanding of the crystallization of food containing air and cells (vegetable or animal tissues).It will be applied to other types of crystallization (fats), to the study of the link between freezing and the health risk, and finally to the study of the cold chain of frozen foods.Résumé : La congélation est un procédé qui permet d'augmenter la durée de conservation des aliments grâce à l'abaissement de la température, qui réduit les cinétiques des réactions de dégradation, et grâce à la solidification de l'eau, qui réduit la disponibilité de celle-ci pour le développement des micro-organismes. Mais la congélation intervient aussi pour transformer et créer une texture souhaitée dans le cas de produits initialement à l’état liquide et destinés à être consommés à l’état congelé, tels que les desserts glacés. Pour ces aliments, la problématique de la congélation est différente puisque les cristaux font partie de la structure du produit final.Mes travaux de recherche ont pour objectif de comprendre les interactions se manifestant à des échelles différentes entre des phénomènes fortement couplés (transfert de chaleur, de matière et écoulement) lors de la congélation des aliments. Ces travaux sont conduits depuis 2002 en tant que maître de conférences à AgroParistech au sein de l’UMR SayFood et au sein de l’unité FRISE. Au départ, centrés sur la congélation des aliments semi-liquides sous cisaillement, mes travaux se sont progressivement élargis à la congélation des aliments solides non poreux et poreux. L’approche développée combine des expérimentations à l’échelle du laboratoire et du pilote semi-industriel avec une modélisation. La dynamique de la structuration de l’aliment est suivie au cours du temps grâce au développement d’outils de pointe permettant la caractérisation aux différentes échelles. Les phénomènes sont étudiés par une approche de simplification raisonnée du produit étudié et/ou du modèle développé. En terme de perspectives, la priorité est de faire le lien entre les échelles : celle de l’aliment soumis à un froid négatif et celle de sa microstructure. D’abord par le suivi expérimental systématique des marqueurs à ces échelles. Puis par le passage d’une échelle à l’autre à l’aide de la modélisation. Cette démarche sera utilisée pour approfondir la compréhension de la cristallisation des aliments en présence d’air et de cellules (tissus végétaux ou animaux). L’approche sera aussi élargie à d’autres types de cristallisation (matières grasses), à l’étude du lien entre la congélation et le risque sanitaire, et enfin à l’étude de la chaîne du froid des aliments surgelés

Analysis of power allocation for NOMA-based D2D communications using GADIA

The new era of IoT brings the necessity of smart synergy for diverse communication and computation entities. The two extremes are, on the one hand, the 5G Ultra-Reliable Low-Latency Communications (URLLC) required for Industrial IoT (IIoT) and Vehicle Communications (V2V, V2I, V2X). While on the other hand, the Ultra-Low Power, Wide-Range, Low Bit-rate Communications, such as Sigfox, LoRa/LoRaWAN, NB-IoT, Cat-M1, etc.; used for smart metering, smart logistics, monitoring, alarms, tracking applications. This extreme variety and diversity must work in synergy, all inter-operating/inter-working with the Internet. The communication solutions must mutually cooperate, but there must be a synergy in a broader sense that includes the various communication solutions and all the processing and storage capabilities from the edge cloud to the deep-cloud. In this paper, we consider a non-orthogonal multiple access (NOMA)-based device to device (D2D) communication system coexisting with a cellular network and utilize Greedy Asynchronous Distributed Interference Avoidance Algorithm (GADIA) for dynamic frequency allocation strategy. We analyze a max–min fairness optimization problem with energy budget constraints to provide a reasonable boundary rate for the downlink to all devices and cellular users in the network for a given total transmit power. A comprehensive simulation and numerical evaluation is performed. Further, we compare the performance of maximum achievable rate and energy efficiency (EE) at a given spectral efficiency (SE) while employing NOMA and orthogonal frequency-division multiple access (OFDMA)

On the scalability of duty-cycled LoRa networks with imperfect SF orthogonality

This papers uses stochastic geometry and queuing theory to study he scalability of long-range (LoRa) networks, accounting for duty cycling restrictions and imperfect spreading factor (SFs) orthogonality. The scalability is characterised by the joint boundaries of device density and traffic intensity per device. Novel cross-correlation factors are used to quantify imperfect SForthogonality. Our results show that a proper characterisation of LoRa orthogonality extends the scalability of the network. They also highlight that for low/medium densities decreasing the SF extends the spanned spectrum of sensing applications characterised by their traffic requirements (i.e. sensing rate). However, for high density (> 104 nodes/Km2 ), the Pareto frontiers converge to a stability limit governed by the SF allocation scheme and the predefined capture thresholds. The results further evince the importance of capturing threshold distribution among the SFs to mitigate the unfair latency

Recycling cellular energy for self-sustainable IoT networks: a spatiotemporal study

This paper investigates the self-sustainability of an overlay Internet of Things (IoT) network that relies on harvesting energy from a downlink cellular network. Using stochastic geometry and queueing theory, we develop a spatiotemporal model to derive the steady state distribution of the number of packets in the buffers and energy levels in the batteries of IoT devices given that the IoT and cellular communications are allocated disjoint spectrum. Particularly, each IoT device is modelled via a two-dimensional discrete-time Markov Chain (DTMC) that jointly tracks the evolution of the data buffers and energy battery. In this context, stochastic geometry is used to derive the energy generation at the batteries and the packet transmission success probability from buffers taking into account the mutual interference from other active IoT devices. To this end, we show the Pareto-Frontiers of the sustainability region, which define the network parameters that ensure stable network operation and finite packet delay. Furthermore, the spatially averaged network performance, in terms of transmission success probability, average queueing delay, and average queue size are investigated. For self-sustainable networks, the results quantify the required buffer size and packet delay, which are crucial for the design of IoT devices and time critical IoT applications

Changes to the Triaxial Composition of the Hydrated Phases (CaO/Al2O3/SiO2) in the Metakaolin/Lime System

This study examines the composition of certain hydrates (calcium silicate, aluminum silicate, and related phases) produced by the pozzolanic reaction of waste-paper sludge that had previously been activated at different temperatures. It summarizes and compares the evolution of the oxide compounds, and records their stability intervals. Changes to their mineralogical composition were analyzed using X-Ray Diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The hydration products from 1 to 360 days of curing time were CSH gels, hydrotalcite-type compounds (LDH), and stratlingite (C2ASH8). CSH gels were employed as substrates for growing other materials and their morphologies were modified from fibrous to hexagonal layers. The composition of the LDH-type compounds observed in the carbonate group varied with changes in curing time. Two LDH-type compound types were identified: (a) with and (b) without magnesium. Stratlingite was the only stable material after long-curing times.Peer reviewe