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Design and Implementation of Partial Firmware UpgradeSun, Silu January 2019 (has links)
Device Firmware Upgrade (DFU) is now widely used on PC and smartphones for users to enjoy the latest applications. The project is derived from the new device of Yohoo and the firmware embedded in the system. This system can guide users on how to breathe through multiple sensory effects to reduce the harm from excessive stress. In order to be applied by different people, some breathing courses and personal settings will be used in the system, which makes the upgrade of the internal firmware of the device more important. However, the firmware upgrade for some embedded devices is not as rapid and convenient as PC and smartphones, which is still erasing and then programming the whole storage. This is a waste of time and meaningless wear to the entire device. In order to solve this problem and improve the efficiency of the firmware upgrade, the partial firmware upgrade is proposed in this project, and the storage method of new codes is improved to get better performance during the partial DFU process. The idea of wear leveling is introduced to extend the lifetime of the internal storage. As a result, the partial firmware upgrade feature was successfully designed and implemented, and integrated and tested on new devices. At the end of this work, the prototype system of the embedded software based on the nRF52832 microcontroller has basically been designed, improved and tested, and some functions which need to be updated instead of the whole firmware can be transmitted via Bluetooth and work normally. For the specific case of partial DFU, the firmware package size that maximizes the update efficiency is obtained through testing. In addition, the flash module in the chip has been divided into multiple portions for the update. The wear-leveling method ensures that when a certain function is updated multiple times, one certain part of the flash will not be overused, but the entire block will be used uniformly to alleviate the adverse effects of data abnormality or loss caused by damaged bits of the flash memory. In addition, the lifetime of the flash memory is prolonged and the industrial waste is reduced at the same time. / Device Firmware Upgrade (DFU) används nu allmänt på PC och smartphones för att användare ska kunna njuta av de senaste applikationerna. Projektet kommer från den nya enheten till Yohoo och den inbyggda programvaran i systemet. Detta system kan vägleda användare om hur man kan andas genom flera sensoriska effekter för att minska skadan från för hög stress. För att kunna tillämpas av olika personer kommer vissa andningskurser och personliga inställningar att användas i systemet, vilket gör uppgraderingen av enhetens interna firmware viktigare. Firmwareuppgraderingen för inbäddade enheter är dock inte lika snabb och bekväm som PC och smartphones, som fortfarande raderar och sedan programmerar hela lagringsutrymmet. Detta är slöseri med tid och meningslöst slitage på hela enheten. För att lösa detta problem och förbättra effektiviteten för uppgradering av firmware föreslås partiell uppgradering av firmware i detta projekt, och lagringsmetoden för nya koder förbättras för att få bättre prestanda under den partiella DFU-processen. Idén om slitstyrning införs för att förlänga livslängden för den interna lagringen. Som ett resultat designades och implementerades delvist firmware uppgraderings funktionen och integrerades och testades på nya enheter. I slutet av detta arbete har prototypsystemet för den inbäddade programvaran baserat på mikrokontrollern nRF52832 i princip utformats, förbättrats och testats, och vissa funktioner som måste uppdateras istället för hela firmware kan överföras via Bluetooth och fungera normalt. För det specifika fallet med delvis uppgradering erhålls firmwarepaketets storlek som maximerar uppdateringseffektiviteten genom testning. Dessutom har flashmodulen i chipet delats upp i flera delar för uppdateringen. Slitstyrningsmetoden gör att när en viss funktion uppdateras flera gånger kommer en viss del av blixt inte att överanvändas, men hela blocket kommer att användas enhetligt för att lindra de negativa effekterna av data i normalitet eller förlust orsakat av skadade bitar av flashminnet. Dessutom förlängs flashminnets livstid teoretiskt och industriavfallet minskas samtidigt.
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Positioning and parking analysis for an indoor positioning system : A comparative study between Bluetooth Low Energy and Ultra Wideband technology / Positionerings- och parkeringsanalys för ett inomhuspositioneringssystem : En jämförande studie mellan Bluetooth Low Energy och Ultra Wideband teknologiBrodin Kont, August January 2019 (has links)
The work done in this report as requested by H&D Wireless is performed by using an already developed real time positioning system called Griffin Enterprise Positioning Service and integratingit with ultrasound sensors for presence detection in order to enable assets to park in a visualized environment being actualized by tagging the asset with radio technology hardware. The testing environment was deployed with radio technology hardware equipped for transmitting and receiving radio signals for position estimation of tagged objects where hardware tags emits radio signals being received by sensing radio technology chips called sensepoints which also serves as communication links for further data processing.The thesis focus is on evaluating how different radio technologies combined with different positioning techniques perform in terms of accuracy and precision in positioning tests to assess eachones positioning performance characteristic and the technologies upsides and downsides.This was firstly evaluated by comparing three different technology positioning techniques based on one for Bluetooth Low Energy and two using Ultra Wideband technology being subject to generic tests including a static, dynamic and a walking positioning test for each technology.These initial tests were utilized as a foreground to evaluate which of the two positioning techniques based on Ultra Wideband technology that would compete in the parking tests alongside Bluetooth Low Energy that would serve as the primary objective to accomplish in the thesis.A final implication on parking tags between the two technologies is that Bluetooth Low Energy had to be implemented with higher requirement restrictions for parking due to insufficient relative accuracy and precision in parking positioning which also limited its ability to be parked in alternative manners explored but with power efficiency as a highly valuable aspect for consideration of this technology. Parking tag using Ultra Wideband technology proved highly successful as it saw large distance margins to be allowed parking in all test cases as well as exhibiting sufficient positioning performance to be considered for alternative parking methods without risk of exposure for failed attempts of parking. / Arbetet utfört i denna rapport på order av H&D Wireless utfördes genom att använda en redan utvecklat realtids positionerings tjänst vid namn Griffin Enterprise Positioning Service och integreradetta system med ultraljudssensorer för närvaro upptäckning för att på så sätt göra det möjligt för tillgångar att parkera i en visualiserad miljö möliggjord av att märkta tillgångar, också kallade taggar, med radioteknologisk hårdvara. Test miljön var utformad med radioteknologisk hårdvara föratt kunna sända och ta emot radio signaler för positionerings estimering av märkta objekt där dessa taggar utsänder radio signaler som upptas av kännande radioteknologiska chip som kallas för sensepoints vilka också tjänar som kommunikationslänkar för vidarearbetning av data.Uppsatsen fokuserar på att utvärder hur radioteknologierna Bluetooth Low Energy och Ultra Wideband tillsammans med förbestämda positionerings tekniker presterar i termer av noggranhet och precision i positionerings tester för att kunna bedöma varderas positionerings karakteristiska prestanda och teknologiernas fördelar och nackdelar. Detta påbörjades genom att utvärdera tre olika teknologiska positioneringstekniker baserade på en med Bluetooth Low Energy och två med Ultra Wideband teknologi som utsattes av generiska tester,som inkluderar ett statisk, dynamiskt och gående positionerings test genomfört för vardera teknologi. Dessa initiala tester användes som grund för att utvärdera vilka två av positionerings teknikerna baserade på Ultra Wideband teknologi som skulle utgöra kandidat i parkerings testerna vid sidan om Bluetooth Low Energy vilket var det primära målet att genomföra i uppsatsen.En följd av att parkera taggar mellan de två teknologierna var att Bluetooth Low Energy krävde högre restriktioner vid implementering för parkering eftersom den uppvisade relativ otillräcklig noggranhet och precision i dess parkerings positionering vilket också begränsade dess förmåga att kunna parkera med alternativ parkings metoder förslagna i rapporten medan dess låga effektförbrukning som en fördelaktig aspekt vid övervägande av tekniken. Att parkera en tagg med Ultra Wideband teknologi demonstrerade framgångsrika resultat då den såg stora avståndsmarginaler för att tillåtas parkera i alla testfall såväl som uppvisande av tillräcklig hög positionerings prestanda för att kunna övervägas med alternativa parkerings metoder utan risk för misslyckade försök till att bli parkerad.
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Design and Evaluation of a logging system in a power-constrained environment / Design och Utvärdering av ett loggsystem i en strömbegränsad miljöAdamsson, Morgan January 2023 (has links)
Logging plays a crucial role in debugging endeavors, assisting technicians in identifying errors and improving the overall sustainability of electrical systems. This thesis focuses on integrating local logging capabilities into the Balise Transmission Module (BTM), a legacy control system that lacks such features. The project also aims to incorporate real-time remote logging functionalities. It should be noted that the BTM does not have power output, necessitating the logging system to derive energy from existing signals while ensuring the safe operation of the control system. The thesis starts by introducing the project’s context, then explains the system architecture and relevant background information. Subsequently, it delves into the design aspects of a power supply that efficiently extracts energy from the control system. Additionally, the thesis explores wireless data transfer solutions and local data storage alternatives, addressing other pertinent details related to the logging system. Finally, it presents an evaluation of the design and an analysis of the results. The power supply design was developed to incorporate in-rush current limiting, a buck converter, and current limiting mechanisms to ensure the safe operation of the BTM. Through simulations, this thesis demonstrates that the power supply can operate within the safe boundaries of the BTM while efficiently harnessing sufficient current to power the system. The wireless transmission protocols investigated in this study were Bluetooth Low Energy (BLE) and WiFi. The thesis evaluates BLE as sufficiently power-efficient but identifies throughput limitations due to the raw data generated by the BTM exceeding the available throughput. On the other hand, WiFi exhibits no throughput issues but consumes excessive power, making it unsuitable for legacy versions of the BTM. Flash memory was designed and implemented as a feasible solution for local storage. / Loggning spelar en avgörande roll i felsökning, vilket underlättar felidentifiering och förbättrar den övergripande hållbarheten för elektiska system. Detta arbete belyser processen att integrera lokala loggningsfunktioner i ett specifikt äldre kontrollsystem, Balise Transmission Module, som helt saknar sådana funktioner. Dessutom strävar projektet efter att integrera realtidsfunktioner för fjärrloggning. I detta särskilda fall saknar det äldre kontrollsystemet utgångseffekt, vilket kräver att loggningssystemet utnyttjar energi från befintliga signaler, utan att påverka kontrollsystemets drift. Arbetet inleds med att introducera projektets sammanhang, följt av en exposition av systemarkitekturen och relevant bakgrundsinformation som är associerad med denna arkitektur. Därefter går arbetet in på designaspekterna av strömförsöjningen som effektivt utvinner energi från kontrollsystemets befintliga signaler. Dessutom utforskas den trådlösa dataöverföringen och alternativ för lokal datalagring, och tar upp andra relevanta detaljer för loggingsystemet. Slutligen presenterar arbetet en utvärdering av designen och en analys av resultaten. Strömförsörjningsdesignen utvecklades för att inkludera begränsning av startström, en buck-omvandlare och strömbegränsningsmekanismer för att säkerställa säker drift av BTM. Genom simuleringar visar detta arbete att strömförsörjningen kan fungera inom de säkra gränserna för BTM samtidigt som den effektivt utvinner tillräcklig ström för att driva systemet. De trådlösa överföringsprotokoll som undersöktes i denna studie var Bluetooth Low Energy (BLE) och WiFi. Arbetet utvärderar BLE som tillräckligt energieffektivt, men identifierar genomströmningsbegränsningar på grund av att den råa data som genereras av BTM överstiger den tillgängliga genomströmningskapaciteten. Å andra sidan uppvisar WiFi inga genomströmningsproblem men förbrukar överdriven ström, vilket gör det olämpligt för äldre versioner av BTM. Flash-minne designades och implementerades som en genomförbar lösning för lokal lagring.
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Kan Anderssons hus bli ett passivhus?Unéus, Viktor January 2016 (has links)
I detta arbete studeras vilka möjligheter det finns för en av 3D hus kunders hus att klara kraven för passiv- eller minienergihus. Baserat på ett projekterat hus studeras hur olika konstruktioner och produktval påverkar husets möjlighet att uppfylla kraven. Trots att samtliga konstruktionsalternativ påstods vara anpassade för energisnåla hus visar vår undersökning att transmissionsförlusterna varierade mycket mellan de olika lösningarna. Även vilka garantier de olika företagen kunde ge gällande lufttäta konstruktioner varierade stort.De områdena som särskilt studeras i detta arbete är energiförluster genom en bostads klimatskal beroende av olika konstruktioner av väggarna, samt vilka fönster och dörrar som är lämpliga.Vår studie visar att utformningen av huset som studerats kommer kräva mycket höga krav på konstruktionen för att huset ska kunna nå kraven för ett passiv- eller minienergihus. Utformningen gör däremot att förlusterna varierar stort mellan de olika valen och det kan därför vara en god idé att se över vilka produkter som ska väljas inom de olika områdena. / This report considers the possibilities to build a passive house or mini-energy house within reasonable demands on manufacturers and construction firms for one of 3D House’s customers. The client has already been in contact with different manufacturers and construction firms with different demands, but with the same warranty of energy efficient materials. In this study there’s a comparison of these demands and warrants show that, even with the same stated terms of low efficient material, the transmission loss vary considerably. Especially the warrants for airtight constructions vary much.Because of the buildings shape it becomes clear that it would need very high requirement on the products and the work to meet the requirements for passive house. The shape of the house does on the other hand make sure that it's a big difference between the different products which would make it a good idea to look over the different chose.The areas there this report is in first hand how the different companies for walls because of that is an area there it's a big different between different choice and it's a big part of the climate shield. It will also have a look over what kind of windows and doors that exist that meet both the requirements for passive house and the costumer.
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Développement de méthodologies de synthèse d’hydroxyméthyl furfural (HMF) à partir de biomasse lignocellulosique. / Development of methodologies for the synthesis of hydroxy methyl furfural (HMF) from lignocellulosic biomass.Despax, Solenne 05 December 2013 (has links)
L'acide furan-2,5-dicarboxylique (FDCA) a été répertorié en 2010 comme l'une des 10 principales molécules bio sourcées, pouvant servir de blocs de construction moléculaire pour remplacer l'acide téréphtalique d'origine pétrochimique, dans la production des polyesters à base de végétal. Ce composé fait partie de la famille des furanes et est obtenu après déshydratation et oxydation de sucres. Une des voies de synthèse utilise un intermédiaire clé, le 5-hydroxyméthylfurfural (HMF). Cependant, il n'existe aujourd'hui aucune production industrielle du HMF, en raison de sa réactivité intrinsèque. La formation de ce composé représente ainsi une des étapes limitantes dans la production de FDCA. Dans ce contexte, nous avons envisagé de nouvelles stratégies de synthèse du HMF économiquement favorables et respectueuses de l'environnement. L'étude de la déshydratation des monosaccharides présents en abondance dans la biomasse lignocellulosique a tout d'abord été effectuée. Les voies de synthèse ont été choisies dans la perspective d'un possible dimensionnement industriel et les coûts de production ont été minimisés afin d'obtenir le HMF à un prix compétitif. Des cristaux de HMF d'une pureté suffisante, pour une application industrielle, ont ainsi été fournis à partir de D-fructose, après une synthèse dans le diméthylsulfoxide sans catalyseur et une extraction liquide-liquide du composé. Le recyclage des solvants organiques utilisés pour la synthèse et pour l'extraction représente un réel avantage du procédé. A partir de D-glucose, la synthèse en milieu organique en deux étapes, sans purification intermédiaire, mais avec seulement une filtration, fournit un sirop de HMF concentré. Le catalyseur utilisé pour l'étape d'isomérisation du D-glucose en D-fructose a été recyclé avec succès. La conversion directe de la cellulose en HMF, dans un milieu contenant un solvant organique, a ensuite été abordée. La stratégie mise en place s'inscrit dans une démarche d'éco-conception visant à obtenir le HMF à partir de biomasse lignocellulosique, sans traitement préalable. L'accessibilité de la cellulose par sa solubilisation dans le milieu réactionnel est le premier défi à relever pour sa conversion ultérieure. La combinaison d'un catalyseur chloré et d'un système composé d'un sel d'ammonium et d'un solvant organique a été efficace pour produire le HMF. Du point de vue de la chimie durable, ce procédé présente de réels avantages tels que l'utilisation de réactifs (sel d'ammonium et catalyseur) peu onéreux et une production de HMF à partir de matières premières renouvelables. L'adaptation de cette méthode à la biomasse lignocellulosique a fourni des rendements modestes mais encourageants pour la suite des travaux. / 2,5-Furan dicarboxylique acid (FDCA) was listed in 2010 as one of the top 10 bio sourced molecules which can serve as building blocks to replace the petrochemical terephthalic acid in the production of polyesters based-plant. This compound belongs to the family of furans and can be obtained after dehydration and oxidation of sugars. One way of synthesis uses a key intermediate, 5-hydroxymethylfurfural (HMF). However, there is currently no commercial production of HMF because of its intrinsic reactivity. The formation of this compound thus represents one of the limiting steps in the production of FDCA. In this context, we have explored new strategies for the synthesis of HMF which could be economically and environmentally favorable. The study of the dehydration of monosaccharides which are abundant in lignocellulosic biomass was first carried out. Synthetic routes have been selected in view of a possible industrial development and in order to reduce as possible as we can the cost of production to obtain the HMF at a competitive price. Crystals of HMF with sufficient purity for industrial applications has been supplied from D-fructose after a synthesis in dimethylsulfoxide without catalyst and after a liquid-liquid extraction. Recycling of organic solvents used for the synthesis and the extraction represents a real benefit for this process. From D-glucose, a synthesis in organic medium in two steps without purification but only filtration afforded a syrup of concentrated HMF. The catalyst used for the isomerization step of the D-glucose into D-fructose was successfully recycled. The direct conversion of cellulose into HMF in a medium composed of an organic solvent was then approached. The implemented strategy is part of an eco-design approach to get the HMF from lignocellulosic biomass, without pretreatment. Accessibility of cellulose by its dissolution in the reaction medium was the first challenge for subsequent conversion. The combination of a chloride catalyst and a system composed of an ammonium salt and an organic solvent was effective to produce HMF. From the view point of sustainable chemistry, this method gathers noticeable advantages such as use of cheap ammonium additive, cheap and naturally abundant metal and allows production of HMF from renewable raw materials. The adjustment method to the lignocellulosic biomass has provided modest but encouraging yields for further work.
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Efektivnost výstavby nízkoenergetických bytových domů / Construction efficiency of low-energy residential buildingsZgúthová, Katarína January 2009 (has links)
Construction of low-energy residential buildings (i.e. houses with low energy demand) in the Czech Republic is not as common as in other countries in the region. This thesis examines the reasons for such development and whether or which obstacles potential buyers face. The analysis of the economic choice between "regular" house and a low-energy building will be primarily based on comparison of basic parameters of both types of constructions. Data for this research will be taken from commercial developers. Quality analysis in the form of detailed interviews with developers, architects and potential buyers will follow. The last section of this thesis will deal with the approach of Czech media towards low-energy development. Presentation of this issue to the public will be examined by the frequency and content of reports.
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Nanoemulsões encapsulando quercetina produzidas pelo método do ponto de inversão da emulsão (EIP): estabilidade físico-química e avaliação da atividade antioxidante in vitro e em produto cárneo / Nanoemulsions encapsulating quercetina produced by the emulsion inversion point method (EIP): physicochemical stability and evaluation of in vitro antioxidant activity and after incorporation in meat productCarli, Cynthia de 24 March 2017 (has links)
A quercetina é um flavonoide com alta atividade antioxidante reconhecida. Devido a este fato, a indústria alimentícia tem buscado alternativas para a aplicação deste bioativo como antioxidante em matrizes alimentícias. No entanto, incorporar a quercetina em formulações alimentícias pode ser desafiador, pois sua molécula tem relativo grau de hidrofobicidade. Os métodos de encapsulação em nanoemulsões podem tornar viável a proteção do flavonoide, bem como permitir sua dispersibilidade em meios aquosos . O objetivo do presente trabalho foi produzir nanoemulsões (fase oleosa: óleo de girassol) encapsulando quercetina pelo método do ponto de inversão da emulsão (EIP, emulsion inversion point), determinando parâmetros de operação que viabilizem um futuro escalonamento do processo, e a realização de um estudo de caso sobre a incorporação das nanodispersões em patê de frango. Os parâmetros de produção que foram avaliados foram : tipo e concentração de tensoativo (razão SOR, razão tensoativo:óleo), concentração de óleo, concentração de cosolvente e velocidade de agitação. Foram produzidas nanoemulsões utilizando dois tensoativos diferentes, Tween 80 e Brij 30. As porcentagens de quercetina encapsulada foram 0,15 e 0,30% (m/m). Dentre estas, a concentração de 0,30% foi a mais viável para a aplicação no patê de frango, por apresentar melhor distribuição de tamanho de gotícula (diâmetro hidrodinâmico), não apresentar variação significativa de oxidação lipídica e maior conservação da quercetina encapsulada por um período de 90 dias. Os valores de tensão interfacial obtidos mostram que a quercetina provoca abaixamento da tensão interfacial do sistema, o que pode indicar que a quercetina forma um complexo com os tensoativos utilizados, fato que influencia decisivamente na sua localização nas nanogotas. Das formulações testadas para patê de frango contendo quercetina, apenas a formulação usando quercetina livre não apresentou boa avaliação nos itens cor e sabor. Tal resultado justifica a necessidade da incorporação da quercetina em nanoemulsões para não causar alterações sensoriais no produto. / Quercetin is a flavonoid with recognized high antioxidant activity Due to this fact, the food industry has been trying to use it as an alternative as a preservative in food matrices. However, incorporating quercetin into food formulations may be challenging due to its relative degree of hydrophobicity. Encapsulation methods in nanoemulsions may render the protection of the flavonoid viable, as well as enable its dispersibility in aqueous media. The objective of the present study was to produce nanoemulsions (oil phase: sunflower oil) encapsulating quercetin by the emulsion inversion point method (EIP), determining operating parameters that enable a future process scale-up. A case study on the incorporation of nanodispersions into chicken patê was also carried out. The production parameters evaluated were: type and concentration of surfactant (SOR ratio, surfactant:oil ratio), soybean oil concentration, cosolvent concentration and stirring speed. Nanoemulsions were produced using two different surfactants, Tween 80 and Brij 30. The percentages of encapsulated quercetin were 0.15 and 0.30% (m / m). Among these, the concentration of 0.30% was the most feasible for application in chicken pâté, since it presented better droplet size distribution (hydrodynamic diameter), did not present significant variation of lipid oxidation and higher capacity of preserving encapsulated quercetina for a period of 90 days. The interfacial tension values obtained show that quercetin lowered the interfacial tension of the system, which may indicate that quercetin forms a complex with the surfactants used, a fact that decisively influences its location in the nanodroplets. Among the formulations tested in chicken pâté containing quercetin, only the formulation using free quercetin did not show good acceptance evaluation on the color and taste itens. Such an evaluation was important as it justifies the need for the incorporation of quercetin into nanoemulsions in order to not cause significant sensorial changes in the product.
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Cryptography for Ultra-Low Power DevicesKaps, Jens-Peter E 04 May 2006 (has links)
Ubiquitous computing describes the notion that computing devices will be everywhere: clothing, walls and floors of buildings, cars, forests, deserts, etc. Ubiquitous computing is becoming a reality: RFIDs are currently being introduced into the supply chain. Wireless distributed sensor networks (WSN) are already being used to monitor wildlife and to track military targets. Many more applications are being envisioned. For most of these applications some level of security is of utmost importance. Common to WSN and RFIDs are their severely limited power resources, which classify them as ultra-low power devices. Early sensor nodes used simple 8-bit microprocessors to implement basic communication, sensing and computing services. Security was an afterthought. The main power consumer is the RF-transceiver, or radio for short. In the past years specialized hardware for low-data rate and low-power radios has been developed. The new bottleneck are security services which employ computationally intensive cryptographic operations. Customized hardware implementations hold the promise of enabling security for severely power constrained devices. Most research groups are concerned with developing secure wireless communication protocols, others with designing efficient software implementations of cryptographic algorithms. There has not been a comprehensive study on hardware implementations of cryptographic algorithms tailored for ultra-low power applications. The goal of this dissertation is to develop a suite of cryptographic functions for authentication, encryption and integrity that is specifically fashioned to the needs of ultra-low power devices. This dissertation gives an introduction to the specific problems that security engineers face when they try to solve the seemingly contradictory challenge of providing lightweight cryptographic services that can perform on ultra-low power devices and shows an overview of our current work and its future direction.
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Metodologias para a determinação das propriedades de impacto de baixa energia de laminados metal-fibra / Methodologies to determine low-energy impact properties of fiber-metal laminatesGualberto, Alan Rodrigo Marinho 13 June 2008 (has links)
Aplicações dos laminados híbridos metal-fibra incluem, além da indústria aeronáutica, as indústrias naval e automobilística. Diferentemente do setor aeronáutico, pesquisas sobre impactos mecânicos nas duas outras áreas da mobilidade são freqüentemente limitadas pela disponibilidade de equipamentos laboratoriais, de modo que é desejável o desenvolvimento de procedimentos de baixo custo para a determinação da resistência e tolerância a danos por impacto dos materiais de construção. Neste trabalho, a resistência a danos por impacto transversal do laminado híbrido metal-fibra Glare-5® foi determinada via três diferentes metodologias. A primeira utiliza um aparato sofisticado aparato Laser-Doppler para monitorar a aceleração e desaceleração de um impactador esférico de aço com 5 mm de diâmetro durante o evento do choque mecânico. O segundo método se baseia apenas nos valores de carga (força aplicada) vs. o tempo de impacto para a obtenção da energia absorvida pelo material. O terceiro considera somente os dados da velocidade do impactador, ou projétil, imediatamente antes e após o impacto. Concluiu-se que os valores de energia obtidos segundo as duas primeiras metodologias são similares, com o Laser-Doppler gerando resultados levemente não-conservadores, comprovando assim a possibilidade da derivação da resistência ao impacto do laminado através de um experimento simples e rápido, que utiliza apenas uma célula de carga digital para a monitoração da força aplicada em função do tempo. O terceiro método apresentou resultados substancialmente superiores às duas primeiras metodologias, sendo classificado como inadequado aos propósitos do projeto. Determinou-se que o laminado híbrido Glare-5®; absorve entre 60% e 80% da energia disponibilizada em impactos ditos leves, no intervalo de 1 a 6 Joules. Por fim, comprovou-se que a rigidez do material (módulo de elasticidade) é a propriedade residual (numa base de tolerância a danos) mais clara e consistentemente degradada pelo impacto previamente aplicado ao material. / Applications of hybrid fiber-metal laminates include, besides aeronautical industry, the automotive and naval industries. Unlike aeronautical field, impact research activities in the former areas of mobility industry are frequently limited by available laboratory equipment, so that it would be desirable to develop low-cost procedures to determine impact resistance and tolerance properties of construction materials. In this work, the transversal (trans-thickness) impact resistance and tolerance of hybrid fiber-metal laminate Glare-5® have been determined via three different methodologies. The first one utilizes sophisticated apparatus comprising a Laser-Doppler device to monitor deceleration/re-acceleration of 5 mm-diameter steel-ball impactor during the mechanical shock event. The second approach merely relies on the force (applied load) vs. impact time for determining the absorbed energy during the dynamic process. The third methodology requires only impactor velocity data points, immediately before and after the impact. It has been concluded that the energy values obtained from Laser- Doppler and load cell methods are very similar, with the former method producing slightly non-conservative results, allowing one to rapidly derive the impact resistance of hybrid laminate materials through very simple experimental set-ups employing digital load cells only. The third method presented somewhat higher results as compared to the concurrent techniques, so that it has been considered as inadequate for the research purposes. This study has shown that the fibre-metal laminate Glare absorbs between 60% and 80% of the apported impact energy during light impact events (ranging from 1 to Joules). Last, but not the least, materials stiffness was the most clearly and consistently imparted residual mechanical property (in a damage tolerance basis) due to the previous applied impact loading.
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Uticaj molekularnih svojstava maltodekstrina na tehnološko ponašanje niskoenergetskih prehrambenih emulzija / Influence of molecular characteristics of maltodextrins on technological behaviour of low-energy food emulsionsDokić-Baucal Ljubica 10 May 2002 (has links)
<p>Apstrakt je obrađen tehnologijama za optičko prepoznavanje teksta (OCR).</p><p>Maltodekstini, hidrolizati skroba niskog stepena konverzije (dekstrozni ekvivalent manji od 20), imaju široku upotrebu u prehrambenoj, kozmetičkoj i farmaceutskoj industriji. U prehrambenoj industriji koriste se u niskoenergetskim prehrambenim emulzijama (majonez, salatni prelivi, namazi) kao zamena za masne materije da bi obezbedili viskozitet, poželjne senzorne osobine i smanjenje energetske vrednosti proizvoda.<br />Viskozitet razblaženih rastora maltodekstrina različitog dekstroznog ekvivalenta i botaničkog porekla meren je kapilarnim viskozimetrom i izračunate su vrednosti unutrašnjeg viskoziteta za pojedine maltodekstrine. Vrednosti untrašnjeg viskoziteta i molekulske mase pokoravaju se zavisnosti Štaudingerove jednačine, iako su molekuli maltodekstrina relativno kratki i ne spadaju u grupu polimera. Utvrđena je mogućnost odredivanja DE- vrednosti viskozimetrijskin putem i izvedene su jednačine za dva opsega DE (5-10 / 10-20).<br />Da bi se ispitalo ponašanje emulzija sa maltodekstrinima (emulgovanje) u procesnim uslovima, kao i osobine fmalnih proizvoda (tečljivost, mazivost) ispitivana je dinamika emulgovanja, veličina kapljica i reološko ponašanje, tj. uticaj različitih faktora na disperzione karakteristike emulzija suncokretovog ulja u vodi stabilizovanih prehrambenim emulgatorom, sa dodatkom maltodekstrina u kontinualnoj fazi.<br />Utvrđeno je da osobine maltodekstina kao što je stepen konverzije (DE-vrednost) tj. veličina molekula maltodekstrina, utiču na dispezione i reološke osobine emulzija. Uticaj koncentracije ulja i maltodekstrina, kao i delimična zamena ulja maltodekstrinom, na osobine emulzija su takode ispitivane. Sa povećanjem koncentracije ulja, pri istoj koncentraciji maltodekstrina u kontinualnoj fazi, emulzije menjaju tip proticanja od pseudoplastičnog preko tiksotropnog do antitiksotrpnog. Atitiksotropija izazvana smicanjem rezultat je formiranja unutrašnje strukture emulzije usled povezivanja kapljica ulja preko molekula maltodekstrina kao i orijentacije i deformacije kapljica ulja i maltodekstrina.<br />Dodatkom maltodekstrina za pri istoj koncentraciju ulja i vremenu emulgovanja dobijene su se emulzije sitnijih kapi.<br />Emulzije sa niskom koncentracijom ulja (30%) sa maltodekstrinom u kontinualnoj fazi bile su nestabilne i pokazivale efekat isplivavanja na površinu (creaming), što je posledica interakcija molekula maltodekstrina i molekula emulgatora Tween 80 u kontinualnoj fazi i na površini kapi.</p> / <p>Abstract was processed by technology for Optical character recognition (OCR).</p><p>Maltodextrins, low converted products of starch hydrolysis (dextrose equivalent less than 20), have been subject of various investigations due to their wide application in food industry, cosmetics and pharmaceuticals. They are used in various low energy food emulsions (mayonnaise, salad dressing, spreads) as fat replacer to provide desirable viscosity, texture and sensory fat-like mouthfeel.<br />Viscosity of diluted maltodextrin solutions of different dextrose equivalent and botanical origin were determined by capillary visometer and intrinsic viscosity [q] of each tested maltodextrin was calculated. The values of [q] together with molecular mass M have shown applicability of Staudinger equation, regardless maltodextrin molecules are rather short. The possibility for the determination of DE-values of maltodextrins by viscometric method has been deduced and the equation was calculated for two ranges of DE (5-10/ 10-20).<br />In order to assess behavior of sunflower oil in water emulsions stabilized with food grade emulsifier with addition of maltodextrins in continuous phase in processing (emulsification), as well as end products in application (pouring, spreading) the emulsification dynamics, globule size changes and rheological behavior, as well as, the influence of different factors on dispersion characteristics of such emulsions were studied.<br />Dispersion and viscous properties of emulsions were influenced by certain specific maltodextrin characteristics such as degree of conversion (DE value) i.e. size of maltodextrin molecules. Influence of oil and maltodextrin concentration and partial substitution of oil with equivalent quantity of maltodextrin were investigated too. With increase of oil concentration at the same concentration of maltodextrin in continuous phase, emulsions undergo changes in flow type from shear-thinning to thixotropic and antithixotropic. Antithxotropy induced by shear, was result of formation of network due to two competing factors; linking of oil droplets through maltodextrin molecules as well as orientation of deformed oil droplets and maltodextrin molecules.<br />Addition of maltodextrin, at the same oil concentration and emulsification time, resulted in formation of emulsions with smaller oil droplets.<br />Emulsions with low oil concentration (30%) with maltodextrin in continuous phase were unstable, showing so called creaming effect. This was mainly due to interactions between maltodextrin and emulsifier Tween 80 molecules which took place in continuous phase and on droplet surfaces.</p>
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