92 research outputs found
Characterization of Moroccan coal waste (Jerada Mine): Impact on physical properties of mortars made of coal waste
No full textInternational audienceThe exploitation of the mine of Jerada in Morocco generates significant quantities of waste rock stored in heaps. This study aims to exploit these mining wastes, as constituents in building materials. A first characterization work has been performed on coal waste, using mineralogical, thermal and physical tests on samples in powder form. The experimental results lead us to the possible recovery of such waste as partial replacement of cement or aggregates in mortars and concretes. An initial exploratory work was the use of coal waste as partial substitution in cementitious mortars, but the low index of activity showed that the waste does not present pozzolanic reactivity. Thus, the following study will be made on mortars with the addition of this waste as a volume replacement of sand with different percentages. In the second part, physical tests were conducted to characterize the mortars before and after heat treatment at 400°C and 600°C, by measuring the apparent density, porosity, gas permeability and the ultrasonic wave propagation. We have observed that porosity increases with the addition of waste and even with the heat treatment, resulting in a remarkably lightweight mortar. On the other hand, the measurement of the apparent gas permeability shows a decrease in permeability with the incorporation of waste. Furthermore, there is an increase of the gas permeability in mortars after thermal treatment, which is probably due to pore volume liberated by the combustion of coal. Measuring ultrasonic wave propagation shows that the sound velocity decreases with the addition of waste and with the heat treatment. This is attributed to the increase in porosity that will limit the waves' velocity. Thus, the thermal processing of these composites is interesting to obtain lightweight and insulating materials. © 2017 University of Mohammed Premier Oujda Morocco
Effect of In-doping on electrochromic behavior of NiO thin films
No full textUndoped and Indium doped Nickel Oxide (NiO) thin layers with different doping content (2, 4, 6 at.%) were successfully deposited on glass and Indium-doped Tin Oxide (ITO) substrates using spray pyrolysis (SP) technique. The effect of indium on the microstructural, morphological, optical, and electrochromic behaviors of NiO films was investigated by X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy, UV–Vis-NIR spectrophotometry. XRD examination shows that all NiO layers have a polycrystalline cubic phase with a preferred orientation along the (111) plane. Raman spectroscopy proves the XRD result. SEM images show nanograins formation in all the sprayed films. The EDS analysis and the elemental mapping reveal the homogeneous distribution of the elements. The optical analysis reveals an average transmission of about 72% in the visible light region and an optical band gap energy of 3.54 eV for the undoped sample. These values decreased with increasing Indium content to reach 65% and 3.46 eV, respectively for the 6 at.% In-doped sample. The electrochromic behavior of NiO films deposited on ITO substrates was measured by cyclic voltammetry in a 2 M KOH aqueous electrolyte. The results show that a specific capacitance of 66 F. g − 1 at 5 mV.s − 1, an optical density variation of 43%, and a coloration efficiency of 93.74 cm2/C were obtained for 2 at.% In doped NiO. These values are considerably higher than those obtained for the undoped films, indicating that the In doping improved the electrochromic performance of nickel oxide films. © 202
Reconfigurable active filtering for mobile wireless application
No full textCe travail de thèse porte sur la conception de dispositifs filtrants accordables, c'est-à-dire pouvant commuter leurs caractéristiques d'un standard à un autre afin de réduire l’encombrement des chaines émission/réception d’un dispositif multistandard. Les filtres les plus utilisés actuellement sont des filtres acoustiques. En effet, ces filtres sont difficilement intégrables dans une technologie silicium et ils restent parmi les dispositifs passifs les plus encombrants du front-end RF. De plus, ils ne permettent pas d’avoir de bonnes performances en pertes d’insertion, en sélectivité et en accordabilité fréquentielle. De ce fait, des solutions alternatives sont à l’origine de ces travaux de thèse. Nous avons considéré tout d’abord un filtre actif qui a la possibilité de régler sa fréquence de résonnance, d’une part à la fréquence de résonnance du système Wifi et d’autre part, à la fréquence de résonnance du système Zigbee. Ensuite, une autre solution a été proposée dans le dernier chapitre qui consiste à réaliser une structure active filtrante bi-bande intégrée. Cette solution a pour avantage de récolter simultanément les données des systèmes opérant dans les deux bandes de fréquences visés. Les résultats obtenus des circuits réalisés sont validés par des simulations et de mesures.This thesis concerns the design of tunable filter devices that can switch theirs characteristics from one standard to another in order to reduce the congestion of emission/reception chain of multi-standard systems. The most commonly used filters are acoustic filters. Indeed, these filters are difficult to be integrated in silicon technology and they remain one of the most bulky passive devices of the RF front-end. In addition, they don’t achieve good performance in insertion loss, frequency selectivity and tunability. Therefore, alternative solutions are at the origin of this thesis. An active filter is considered with the possibility of adjusting the resonance frequency: the resonant frequency of the Wifi system and the resonance frequency of the Zigbee system. Moreover, another solution is proposed in the last chapter, which consists to achieve a dual band structure of integrated active filter. This solution has the advantage to simultaneously collect data provided from the operating systems located in the two specified frequencies bands. Simulations and measurements validate the results of the realized circuits
Filtrage actif intégré reconfigurable pour la téléphonie sans fil
No full textThis thesis concerns the design of tunable filter devices that can switch theirs characteristics from one standard to another in order to reduce the congestion of emission/reception chain of multi-standard systems. The most commonly used filters are acoustic filters. Indeed, these filters are difficult to be integrated in silicon technology and they remain one of the most bulky passive devices of the RF front-end. In addition, they don’t achieve good performance in insertion loss, frequency selectivity and tunability. Therefore, alternative solutions are at the origin of this thesis. An active filter is considered with the possibility of adjusting the resonance frequency: the resonant frequency of the Wifi system and the resonance frequency of the Zigbee system. Moreover, another solution is proposed in the last chapter, which consists to achieve a dual band structure of integrated active filter. This solution has the advantage to simultaneously collect data provided from the operating systems located in the two specified frequencies bands. Simulations and measurements validate the results of the realized circuits.Ce travail de thèse porte sur la conception de dispositifs filtrants accordables, c'est-à-dire pouvant commuter leurs caractéristiques d'un standard à un autre afin de réduire l’encombrement des chaines émission/réception d’un dispositif multistandard. Les filtres les plus utilisés actuellement sont des filtres acoustiques. En effet, ces filtres sont difficilement intégrables dans une technologie silicium et ils restent parmi les dispositifs passifs les plus encombrants du front-end RF. De plus, ils ne permettent pas d’avoir de bonnes performances en pertes d’insertion, en sélectivité et en accordabilité fréquentielle. De ce fait, des solutions alternatives sont à l’origine de ces travaux de thèse. Nous avons considéré tout d’abord un filtre actif qui a la possibilité de régler sa fréquence de résonnance, d’une part à la fréquence de résonnance du système Wifi et d’autre part, à la fréquence de résonnance du système Zigbee. Ensuite, une autre solution a été proposée dans le dernier chapitre qui consiste à réaliser une structure active filtrante bi-bande intégrée. Cette solution a pour avantage de récolter simultanément les données des systèmes opérant dans les deux bandes de fréquences visés. Les résultats obtenus des circuits réalisés sont validés par des simulations et de mesures
Characterization of Moroccan Coal Waste Jerada Mine): Impact on Physical Properties of Mortars Made of Coal Waste
No full textInternational audienc
Study of the mechanical behavior of light mortars produced by thermal treatment, with coal waste of Jerada mine (eastern Morocco)
No full textInternational audienc
Helsinki Startup City Guide
No full textThis thesis is a product-oriented thesis. The aim of the thesis is to create valuable and quality content for the commissioning party, StartUs. The content is educational and takes form as a guide. The guide was done with the support of Haaga-Helia StartUp School.
The theoretical framework consists of startup and content marketing theory, and is essential in providing the reader of this thesis the understanding of why the guide is important for the commissioning party and its target audience.
Defining a startup can be tricky as there are several different definitions to what is a startup. In addition, not all startups are alike as there are multiple types of startups each of its own goals and definition of success. All of the startup types can benefit from incorporating lean startup methodologies. Some of the core principles of the lean startup methodology are Customer Development and the build-measure-learn loop both of which ultimately allow startups to avoid failing and creating a greater demand for their product or service through the understanding of the true needs of the customers.
Nowadays, content marketing is imperative for a company in order to gain visibility and reach the right audience. In order to stand out from competitors and achieve the attention of consumers and fulfill the company’s business goals, relevant and valuable content must be produced and distributed.
The product of this thesis is the Helsinki Startup City Guide. It is a practical guide for startup enthusiasts and everyone interested and considering to establish a startup company in Helsinki. The guide lists the most relevant information one must know about the startup ecosystem of Helsinki.
This thesis and the product were produced within three weeks due to limited time constraints. Both the author and the commissioning parties are pleased with the end result of the product
Improving the performance of binary and ternary planar organic photovoltaic solar cells through the synthesis and the characterization of hybrid buffer layers : MoO3MoS2 and MoO3/CuI
No full textLe présent travail de thèse consiste à améliorer les performances des cellules photovoltaïques organiques à base de l’hétérojonction planaire : Alpha-Sexithiophene (α-6T)/Fullerène(C60) via l’utilisation des couches tampons anodiques hybrides MoO3:MoS2 et MoO3/CuI. La première partie de ce travail de thèse est consacrée à la synthèse des couches tampons hybrides MoO3:MoS2 à une température relativement basse (< 300 °C) pour éviter la dégradation des matériaux constitiant la cellule. A ce propos, nous avons proposé dans cette étude de synthétiser les couches hybrides MoO3:MoS2 en utilisant une technique originale de sulfuration dite "RTA-CVD" d'un film mince de MoO3. Les résultats de l’analyse par XPS ont montré qu'il est possible d'obtenir des films hybride de MoO3:MoS2 par un traitement thermique à 220 °C pendant 5 min. L’application des couches MoO3:MoS2 dans les cellules montre une amélioration en performances. Le deuxième volet de cette thèse quant à lui s’intéresse à l’étude de l’effet de la couche tampons MoO3/CuI sur les performances de la cellule α-6T/C60. Les résultats ont montré que la double couche tampon anodique MoO3/CuI(1.5 nm) permet d’obtenir une amélioration considérable dans les performances des cellules. Ceci a été expliqué via differentes caractérisations de la couche de α-6T. A fin de mieux améliorer le rendement de la cellule α-6T/C60 nous avons opté pour la « stratégie ternaire » en utilisant une troisième couche active d’AlPcCl pour élargir le domaine d’absorption de la cellule. Les résultats obtenus montrent une amélioration significative de rendement de ces cellules par rapport aux cellules binaires étudiées.The present thesis work consists of improving the performances of organic photovoltaic solar cells based on planar heterojunction: Alpha-Sexithiophene (α-6T)/Fullerene(C60) by using hybrid anode buffers layers MoO3:MoS2 and MoO3/CuI. The main problem of this thesis work was the synthesis of the MoO3:MoS2 hybrid buffer layers at a relatively low temperature (< 300°C) to prevent the degradation of the materials constituting the cell. In this regard, we have proposed in this study to synthesize the hybrid layer MoO3:MoS2 using an original sulfuration technique called "RTA-CVD" of a thin film of MoO3. The XPS results analysis showed that it is possible to obtain hybrid films of MoO3:MoS2 by a heat treatment at 220°C for 5 min. The insertion of the hybride layers : MoO3:MoS2 in the cells shows an improvement in their performances. The second part of this thesis was the study of the effect of the MoO3/CuI anode buffer layer on the performances of the solar celles based on the hetejojunction α-6T/C60. The results showed that the double anodic buffer layer MoO3/CuI(1.5 nm) provides a considerable improvement in cells performances. This has been explained through different characterizations of the α-6T layer. In order to improve more the performances of this cell, we opted for the «ternary strategy» by using a third active layer of the AlPcCl to widen the absorption domain of the cell. The results show a significant improvement in the the power conversion efficiency compared to the studied binary cells
Propriétés Optiques Non Linéaires de l'Oxyde de Zinc: Elaboration, Charactérisation, Propriétés Optiques, Génération de la troisième Harmonique
No full textExactness Results for Generalized Ambrosetti-Brezis-Cerami Problem and Related One-dimensional Elliptic Equations
No full textWe consider the boundary problem
-(φp(u'))' = φα(u) + λφβ(u) in (0, 1)
u(0) = u(1) = 0
where φp(x) = |x|p-2 x, p, α, β > 1 and λ ∈ ℝ*. We give the exact number of solutions for all λ and most values of α, β, p > 1. In the particular case where 1 < β < p = 2 < α, we resolve completely a problem suggested by A. Ambrosetti, H. Brezis and G. Cerami and which was partially solved by S. Villegas.Mathematic
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