Síntese e caracterização de pigmentos nanométricos encapsulados pelos métodos dos precursores poliméricos, hidrotermal de microondas e co-precipitação associado à química sol-gel convencional

The demand for materials with high consistency obtained at relatively low temperatures has been leveraging the search for chemical processes substituents of the conventional ceramic method. This paper aims to obtain nanosized pigments encapsulated (core-shell) the basis of TiO2 doped with transition metals (Fe, Co, Ni, Al) through three (3) methods of synthesis: polymeric precursors (Pechini); hydrothermal microwave, and co-precipitation associated with the sol-gel chemistry. The study was motivated by the simplicity, speed and low power consumption characteristic of these methods. Systems costs are affordable because they allow achieving good control of microstructure, combined with high purity, controlled stoichiometric phases and allowing to obtain particles of nanometer size. The physical, chemical, morphological, structural and optical properties of the materials obtained were analyzed using different techniques for materials characterization. The powder pigments were tested in discoloration and degradation using a photoreactor through the solution of Remazol yellow dye gold (NNI), such as filtration, resulting in a separation of solution and the filter pigments available for further UV-Vis measurements . Different calcination temperatures taken after obtaining the post, the different methods were: 400 º C and 1000 º C. Using a fixed concentration of 10% (Fe, Al, Ni, Co) mass relative to the mass of titanium technologically and economically enabling the study. By transmission electron microscopy (TEM) technique was possible to analyze and confirm the structural formation nanosized particles of encapsulated pigment, TiO2 having the diameter of 20 nm to 100 nm, and thickness of coated layer of Fe, Ni and Co between 2 nm and 10 nm. The method of synthesis more efficient has been studied in the work co-precipitation associated with sol-gel chemistry, in which the best results were achieved without the need for the obtainment of powders the calcination process

FTE-LEACH: um protocolo energeticamente eficiente e tolerante a falhas aplicado às redes industriais de sensores sem fio

A Wireless Sensor Network (WSN) consists of distributed devices in an area in order to monitor physical variables such as temperature, pressure, vibration, motion and environmental conditions in places where wired networks would be difficult or impractical to implement, for example, industrial applications of difficult access, monitoring and control of oil wells on-shore or off-shore, monitoring of large areas of agricultural and animal farming, among others. To be viable, a WSN should have important requirements such as low cost, low latency, and especially low power consumption. However, to ensure these requirements, these networks suffer from limited resources, and eventually being used in hostile environments, leading to high failure rates, such as segmented routing, mes sage loss, reducing efficiency, and compromising the entire network, inclusive. This work aims to present the FTE-LEACH, a fault tolerant and energy efficient routing protocol that maintains efficiency in communication and dissemination of data.This protocol was developed based on the IEEE 802.15.4 standard and suitable for industrial networks with limited energy resources

High resolution study of narrow tailed radio galaxies in clusters

Clusters of galaxies are the most massive and large gravitationally bounded systems in the whole Universe. Their study is of fundamental importance to constrain cosmological parameters and to obtain informations regarding various kind of emission in different wavebands. In particular, in the radio domain, beside the diffuse emission, the study is focused on the radio galaxies emission. Radio galaxies in clusters can have peculiar morphology, since they interact with the intracluster medium (ICM) in which they are embedded. Particularly, in this thesis we focused our attention on the so-called Narrow-Angle Tailed radio galaxies (NAT), which present radio jets that are bent at extreme angle, up to 90 degrees, from their original orientation. Some NAT show a narrow extended structure and the two radio tails are not resolved even with high resolution radio observations. An example is provided by the source IC310, in the Perseus Cluster, whose structure has been recently interpreted as due to Doppler boosting effects of a relativistic jet oriented at a small angle with respect to the line of sight. If the structure is due to relativistic effects, this implies that the jets are relativistic at about 400 kpc from the core, but this is in contrast with unified models, which predict that for low-power radio source (NAT are classified as FRI radio galaxies) the jets decelerate to sub-relativistic speed within a few kpc from the core. To investigate this scientific topic, in this thesis we have analyzed the innermost structure of a sample of eleven radio galaxies showing a very narrow NAT structure. We can conclude that the structure of these radio galaxies is different from that of IC310. These radio galaxies are indeed strongly influenced by environmental effects and are similar to classical NAT sources.

Brands, Close Relationships, and Consumer Well-Being

Consumers have relationships with other people, and they have relationships with brands similar to the ones they have with other people. Yet, very little is known about how brand and interpersonal relationships relate to one another. Even less is known about how they jointly affect consumer well-being. The goal of this research, therefore, is to examine how brand and interpersonal relationships influence and are influenced by consumer well-being. Essay 1 uses both empirical methods and surveys from individuals and couples to investigate how consumer preferences in romantic couples, namely brand compatibility, influences life satisfaction. Using traditional statistical techniques and multilevel modeling, I find that the effect of brand compatibility, or the extent to which individuals have similar brand preferences, on life satisfaction depends upon power in the relationship. For high power partners, brand compatibility has no effect on life satisfaction. On the other hand, for low power partners, low brand compatibility is associated with decreased life satisfaction. I find that conflict mediates the link between brand compatibility and power on life satisfaction. In Essay 2 I again use empirical methods and surveys to investigate how resources, which can be considered a form of consumer well-being, influence brand and interpersonal relations. Although social connections have long been considered a fundamental human motivation and deemed necessary for well-being (Baumeister and Leary 1995), recent research has demonstrated that having greater resources is associated with weaker social connections. In the current research I posit that individuals with greater resources still have a need to connect and are using other sources for connection, namely brands. Across several studies I test and find support for my theory that resource level shifts the preference of social connection from people to brands. Specifically, I find that individuals with greater resources have stronger brand relationships, as measured by self-brand connection, brand satisfaction, purchase intentions and willingness to pay with both existing brand relationships and with new brands. This suggests that individuals with greater resources place more emphasis on these relationships. Furthermore, I find that resource level influences the stated importance of brand and interpersonal relationships, and that having or perceiving greater resources is associated with an increased preference to engage with brands over people. This research demonstrates that there are times when people prefer and seek out connections with brands over other people, and highlights the ways in which our brand and interpersonal relationships influence one another.

Multistabilities and symmetry-broken one-color and two-color states in closely coupled single-mode lasers

We theoretically investigate the dynamics of two mutually coupled, identical single-mode semi-conductor lasers. For small separation and large coupling between the lasers, symmetry-broken one-color states are shown to be stable. In this case the light outputs of the lasers have significantly different intensities while at the same time the lasers are locked to a single common frequency. For intermediate coupling we observe stable symmetry-broken two-color states, where both lasers lase simultaneously at two optical frequencies which are separated by up to 150 GHz. Using a five-dimensional model, we identify the bifurcation structure which is responsible for the appearance of symmetric and symmetry-broken one-color and two-color states. Several of these states give rise to multistabilities and therefore allow for the design of all-optical memory elements on the basis of two coupled single-mode lasers. The switching performance of selected designs of optical memory elements is studied numerically.

Piezoelectric energy harvesting using blood-flow-like excitation for implantable devices

The goal of this research is to produce a system for powering medical implants to increase the lifetime of the implanted devices and reduce the battery size. The system consists of a number of elements – the piezoelectric material for generating power, the device design, the circuit for rectification and energy storage. The piezoelectric material is analysed and a process for producing a repeatable high quality piezoelectric material is described. A full width half maximum (FWHM) of the rocking curve X-Ray diffraction (XRD) scan of between ~1.5° to ~1.7° for test wafers was achieved. This is state of the art for AlN on silicon and means devices with good piezoelectric constants can be fabricated. Finite element modelling FEM) was used to design the structures for energy harvesting. The models developed in this work were established to have an accuracy better than 5% in terms of the difference between measured and modelled results. Devices made from this material were analysed for power harvesting ability as well as the effect that they have on the flow of liquid which is an important consideration for implantable devices. The FEM results are compared to experimental results from laser Doppler vibrometry (LDV), magnetic shaker and perfusion machine tests. The rectifying circuitry for the energy harvester was also investigated. The final solution uses multiple devices to provide the power to augment the battery and so this was a key feature to be considered. Many circuits were examined and a solution based on a fully autonomous circuit was advanced. This circuit was analysed for use with multiple low power inputs similar to the results from previous investigations into the energy harvesting devices. Polymer materials were also studied for use as a substitute for the piezoelectric material as well as the substrate because silicon is more brittle.

Method to Improve the Conversion Gain Flatness of Transformer-Coupled Mixers

A 4-10 GHz, on-chip balun based current commutating mixer is proposed. Tunable resistive feedback is used at the transconductance stage for wideband response, and interlaced stacked transformer is adopted for good balance of the balun. Measurement results show that a conversion gain of 13.5 dB, an IIP3 of 4 dBm and a noise figure of 14 dB are achieved with 5.6 mW power consumption under 1.2 V supply. The simulated amplitude and phase imbalance is within 0.9 dB and ±2◦ over the band.

New Frontiers in Energy-Efficient Computing

Energy-efficient computing remains a critical challenge across the wide range of future data-processing engines — from ultra-low-power embedded systems to servers, mainframes, and supercomputers. In addition, the advent of cloud and mobile computing as well as the explosion of IoT technologies have created new research challenges in the already complex, multidimensional space of modern and future computer systems. These new research challenges led to the establishment of the IEEE Rebooting Computing Initiative, which specifically addresses novel low-power solutions and technologies as one of the main areas of concern.With this in mind, we thought it timely to survey the state of the art of energy-efficient computing.

Achieving Energy Saving through Proxying Applications on behalf of Idle Devices

Several studies in the past have revealed that network end user devices are left powered up 24/7 even when idle just for the sake of maintaining Internet connectivity. Network devices normally support low power states but are kept inactive due to their inability to maintain network connectivity. The Network Connectivity Proxy (NCP) has recently been proposed as an effective mechanism to impersonate network connectivity on behalf of high power devices and enable them to sleep when idle without losing network presence. The NCP can efficiently proxy basic networking protocol, however, proxying of Internet based applications have no absolute solution due to dynamic and non-predictable nature of the packets they are sending and receiving periodically. This paper proposes an approach for proxying Internet based applications and presents the basic software architectures and capabilities. Further, this paper also practically evaluates the proposed framework and analyzes expected energy savings achievable under-different realistic conditions.

High-Performance WSe2 CMOS Technology and Integrated Circuits.

Because of their extraordinary structural and electrical properties, two dimensional materials are currently being pursued for applications such as thin-film transistors and integrated circuit. One of the main challenges that still needs to be overcome for these applications is the fabrication of air-stable transistors with industry-compatible complementary metal oxide semiconductor (CMOS) technology. In this work, we experimentally demonstrate a novel high performance air-stable WSe2 CMOS technology with almost ideal voltage transfer characteristic, full logic swing and high noise margin with different supply voltages. More importantly, the inverter shows large voltage gain (~38) and small static power (Pico-Watts), paving the way for low power electronic system in 2D materials.

Parallel Cyclostationarity-Exploiting Algorithm for Energy-Efficient Spectrum Sensing

The evolution of wireless communication systems leads to Dynamic Spectrum Allocation for Cognitive Radio, which requires reliable spectrum sensing techniques. Among the spectrum sensing methods proposed in the literature, those that exploit cyclostationary characteristics of radio signals are particularly suitable for communication environments with low signal-to-noise ratios, or with non-stationary noise. However, such methods have high computational complexity that directly raises the power consumption of devices which often have very stringent low-power requirements. We propose a strategy for cyclostationary spectrum sensing with reduced energy consumption. This strategy is based on the principle that p processors working at slower frequencies consume less power than a single processor for the same execution time. We devise a strict relation between the energy savings and common parallel system metrics. The results of simulations show that our strategy promises very significant savings in actual devices.

Diseño de una turbina experimental de vapor de baja potencia.

Este trabajo se enfoca en el diseño de una turbina de vapor de carácter experimental para simular, en un laboratorio de transferencia térmica, la dinámica propia de una turbina de mayor tamaño en el circuito secundario de un ciclo de potencia. La máquina diseñada produciría 185 kW de potencia en el eje a 9.000 RPM con un rendimiento interno del 88 %, tomando en la entrada 0,4 kg/s de vapor saturado a 40 bar y descargando a una presión de 1,5 bar. Se desarrolló la teoría de turbomáquinas necesaria para realizar los cálculos fuidodinámicos y se propuso un método de diseño apropiado para el alcance del trabajo. Se decidió que la turbina sería de tres etapas, dos Curtis y una de impulso, y se realizaron los cálculos correspondientes. Una vez que el diseño fluidodinámico estaba definido, se procedió a dimensionar los distintos elementos mecánicos, con el alcance correspondiente a ingeniería conceptual y básica. Se realizaron detalladamente los cálculos propios del dimensionado del rotor (eje y discos), rodamientos, carcasa, válvula de seguridad de presión y asociados. Además se presentó el diseño conceptual de los elementos restantes, sistema de control y otros auxiliares. Finalmente, se realizaron los modelos en software 3D de todas las piezas y se produjeron los planos correspondientes.

The Performance Characteristics of a Surface-Modified Cutting Tool

In the past, many papers have been presented which show that the coating of cutting tools often yields decreased wear rates and reduced coefficients of friction. Although different theories are proposed, covering areas such as hardness theory, diffusion barrier theory, thermal barrier theory, and reduced friction theory, most have not dealt with the question of how and why the coating of tool substrates with hard materials such as Titanium Nitride (TiN), Titanium Carbide (TiC) and Aluminium Oxide (Al203) transforms the performance and life of cutting tools. This project discusses the complex interrelationship that encompasses the thermal barrier function and the relatively low sliding friction coefficient of TiN on an undulating tool surface, and presents the result of an investigation into the cutting characteristics and performance of EDMed surface-modified carbide cutting tool inserts. The tool inserts were coated with TiN by the physical vapour deposition (PVD) method. PVD coating is also known as Ion-plating which is the general term of the coating method in which the film is created by attracting ionized metal vapour in this the metal was Titanium and ionized gas onto negatively biased substrate surface. Coating by PVD was chosen because it is done at a temperature of not more than 5000C whereas chemical Vapour Deposition CVD process is done at very high temperature of about 8500C and in two stages of heating up the substrates. The high temperatures involved in CVD affects the strength of the (tool) substrates. In this study, comparative cutting tests using TiN-coated control specimens with no EDM surface structures and TiN-coated EDMed tools with a crater-like surface topography were carried out on mild steel grade EN-3. Various cutting speeds were investigated, up to an increase of 40% of the tool manufacturer’s recommended speed. Fifteen minutes of cutting were carried out for each insert at the speeds investigated. Conventional tool inserts normally have a tool life of approximately 15 minutes of cutting. After every five cuts (passes) microscopic pictures of the tool wear profiles were taken, in order to monitor the progressive wear on the rake face and on the flank of the insert. The power load was monitored for each cut taken using an on-board meter on the CNC machine to establish the amount of power needed for each stage of operation. The spindle drive for the machine is an 11 KW/hr motor. Results obtained confirmed the advantages of cutting at all speeds investigated using EDMed coated inserts, in terms of reduced tool wear and low power loads. Moreover, the surface finish on the workpiece was consistently better for the EDMed inserts. The thesis discusses the relevance of the finite element method in the analysis of metal cutting processes, so that metal machinists can design, manufacture and deliver goods (tools) to the market quickly and on time without going through the hassle of trial and error approach for new products. Improvements in manufacturing technologies require better knowledge of modelling metal cutting processes. Technically the use of computational models has a great value in reducing or even eliminating the number of experiments traditionally used for tool design, process selection, machinability evaluation, and chip breakage investigations. In this work, much interest in theoretical and experimental investigations of metal machining were given special attention. Finite element analysis (FEA) was given priority in this study to predict tool wear and coating deformations during machining. Particular attention was devoted to the complicated mechanisms usually associated with metal cutting, such as interfacial friction; heat generated due to friction and severe strain in the cutting region, and high strain rates. It is therefore concluded that Roughened contact surface comprising of peaks and valleys coated with hard materials (TiN) provide wear-resisting properties as the coatings get entrapped in the valleys and help reduce friction at chip-tool interface. The contributions to knowledge: a. Relates to a wear-resisting surface structure for application in contact surfaces and structures in metal cutting and forming tools with ability to give wear-resisting surface profile. b. Provide technique for designing tool with roughened surface comprising of peaks and valleys covered in conformal coating with a material such as TiN, TiC etc which is wear-resisting structure with surface roughness profile compose of valleys which entrap residual coating material during wear thereby enabling the entrapped coating material to give improved wear resistance. c. Provide knowledge for increased tool life through wear resistance, hardness and chemical stability at high temperatures because of reduced friction at the tool-chip and work-tool interfaces due to tool coating, which leads to reduced heat generation at the cutting zones. d. Establishes that Undulating surface topographies on cutting tips tend to hold coating materials longer in the valleys, thus giving enhanced protection to the tool and the tool can cut faster by 40% and last 60% longer than conventional tools on the markets today.

Integración de aerogeneradores de baja potencia en la red de baja tensión

[EN] The current energy model is unsustainable economically, environmentally and socially forcing develop renewable technologies that modify the concept to the responsible use. The use of low-power wind turbines has generally been limited to isolated which has slowed their development systems. The study addresses this technological niche to deepen their study of integration of electricity on a low voltage network. For this first wind potential with Homer software is evaluated. Various scenarios are simulated in "The IEEE European Test Low Voltage Feeder" network using the software OpenDSS widely used in studies of Generation Distributed by EPRI (Electric Power Research Institute).

Développement de procédés technologiques pour une intégration 3D monolithique de dispositifs nanoélectroniques sur CMOS

Résumé : Le transistor monoélectronique (SET) est un dispositif nanoélectronique très attractif à cause de son ultra-basse consommation d’énergie et sa forte densité d’intégration, mais il n’a pas les capacités suffisantes pour pouvoir remplacer complètement la technologie CMOS. Cependant, la combinaison de la technologie SET avec celle du CMOS est une voie intéressante puisqu’elle permet de profiter des forces de chacune, afin d’obtenir des circuits avec des fonctionnalités additionnelles et uniques. Cette thèse porte sur l’intégration 3D monolithique de nanodispositifs dans le back-end-of-line (BEOL) d’une puce CMOS. Cette approche permet d’obtenir des circuits hybrides et de donner une valeur ajoutée aux puces CMOS actuelles sans altérer le procédé de fabrication du niveau des transistors MOS. L’étude se base sur le procédé nanodamascène classique développé à l’UdeS qui a permis la fabrication de dispositifs nanoélectroniques sur un substrat de SiO2. Ce document présente les travaux réalisés sur l’optimisation du procédé de fabrication nanodamascène, afin de le rendre compatible avec le BEOL de circuits CMOS. Des procédés de gravure plasma adaptés à la fabrication de nanostructures métalliques et diélectriques sont ainsi développés. Le nouveau procédé nanodamascène inverse a permis de fabriquer des jonctions MIM et des SET métalliques sur une couche de SiO2. Les caractérisations électriques de MIM et de SET formés avec des jonctions TiN/Al2O3 ont permis de démontrer la présence de pièges dans les jonctions et la fonctionnalité d’un SET à basse température (1,5 K). Le transfert de ce procédé sur CMOS et le procédé d’interconnexions verticales sont aussi développés par la suite. Finalement, un circuit 3D composé d’un nanofil de titane connecté verticalement à un transistor MOS est réalisé et caractérisé avec succès. Les résultats obtenus lors de cette thèse permettent de valider la possibilité de co-intégrer verticalement des dispositifs nanoélectroniques avec une technologie CMOS, en utilisant un procédé de fabrication compatible.