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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Étude des particules fines et ultrafines en suspension dans l'air au Liban : caractérisation physicochimique et évaluation des effets toxicologiques sur des cellules pulmonaires humaines BEAS-2B / The study of air suspended fine and ultrafine particles in Lebanon : physicochemical characterization and evaluation of toxicological effects on human lung cells BEAS-2B

Borgie, Mireille 15 April 2014 (has links)
Les principaux objectifs de cette étude, une des premières menée au Liban, étaient d’acquérir une meilleure connaissance des caractéristiques physico-chimiques des particules atmosphériques fines (PF ou PM₂.₅₋₀.₃) et ultrafines (PUF ou PM₀.₃), et d’évaluer in vitro, leur potentiel toxique sur des cellules épithéliales bronchiques humaines (BEAS-2B). L’échantillonnage de PF et de PUF a été mené au Liban à la fois sur un site urbain (Sin El-Fil, du 18 mai au 2 sept. 2011) et un site rural (Beije, du 5 sept. au 28 oct. 2011). Les PF et les PUF ont fait l’objet d’une caractérisation physico-chimique par la détermination de leur composition en éléments et ions inorganiques, carbone total et composés organiques. Ensuite, des échantillons composites de PF et de PUF ont été préparés afin d’exposer les cellules BEAS-2B et évaluer les mécanismes toxiques sous-jacents. Nos résultats ont montré une influence des sources de combustion plus notable pour les particules collectées sur le site urbain, et cela par la présence de carbone total, de composés organiques, de métaux et d’ions inorganiques secondaires à des niveaux de concentration supérieurs à ceux rencontrés sur le site rural. D’autre part, une cytotoxicité plus prononcée a été provoquée par les PUF par comparaison aux PF. Les mécanismes de génotoxicité et de modifications épigénétiques que nous avons étudiés, à savoir l’activation métabolique des composés organiques, la modification de l’expression de trois microARNs, l’activation de la télomérase et l’induction de cassures au niveau de l’ADN, ont été induits par les deux échantillons de PF, avec un effet plus prononcé pour les particules d’origine urbaine. L’exposition des cellules BEAS-2B aux PF collectées, notamment celles d’origine urbaine, pourraient donc favoriser la transformation des cellules pulmonaires en cellules immortelles, et par conséquent, l’initiation ou la promotion de la cancérogenèse broncho-pulmonaire. / The objectives of this study, one of the first conducted in Lebanon, were to acquire a better knowledge on the physico-chemical characteristics of atmospheric fine particles (FP or PM₂.₅₋₀.₃) and ultrafine ones (UFP or PM₀.₃), and to assess their potential toxicity. Particles were collected at two coastal sites between may and sept. 2011 at Sin El-Fil (urban site in Greater Beirut), and between sept. and oct. 2011 at Bejje (rural site). After sampling, FP and UFP were subjected to a physico-chemical characterization by quantifying their inorganic ions and elements, total carbon and organic compounds contents. Then, composite samples of FP and UFP were prepared in order to expose bronchial epithelial cells (BEAS-2B) in culture, and therefore to assess the underlying toxic mechanisms. Our results showed an influence of combustion sources especially for urban particles that are richer in total carbon, organic compounds, metals and secondary inorganic ions than rural ones. On the other hand, a more pronounced cytotoxicity was caused by UFP when compared to FP. In addition, epigenetic modifications and genotoxicity mechanisms, such as metabolic activation of organic compounds, changes in three microRNAs expression, telomerase activation and DNA breaks induction, which are potentially involved in the initiation and promotion of carcinogenesis, were induced by the two samples of FP, with a more pronounced effect of urban particles. Exposure of BEAS-2B cells to collected FP, especially urban ones, may therefore induce the transformation of lung cells to immortal cells, and consequently the initiation or the promotion of broncho-pulmonary carcinogenesis.
42

Skrivundervisning i förändring / Changes in Approaches to Writing Instruction

Franck, Alice January 2022 (has links)
I studien undersöks hur undervisningen i svenska på gymnasiet, främst i kursen Svenska 3, tycks ha påverkats av den uppgift i PM-skrivande som infördes i det nationella provet i samband med att Gy11 trädde i kraft. I studien analyseras fem läroböcker: två från före 2011, två från åren kring 2011 samt den senast utgivna boken för Svenska 3. Böckerna analyseras utifrån Ivaničs (2004) ramverk av sex skrivdidaktiska diskurser. Därmed kan en eventuell skillnad i synen på skrivande och skrivundervisning skönjas. Resultaten visar att det utredande/vetenskapliga skrivandet fått ta allt större plats och ägnas ett tydligare fokus i de senare läroböckerna än i de tidigare. Vidare är processdiskursen och kreativitetsdiskursen dominerande i de tidigare böckerna medan genrediskursen och delvis färdighetsdiskursen dominerar i de nyare. Resultaten visar vidare att texttypen PM fått en ny innebörd. I de tidigare böckerna definieras texttypen som en lista medan den i de senare böckerna beskrivs som en utredande/vetenskaplig texttyp. Dessutom framstår PM som en av de viktigaste utredande/vetenskapliga texttyperna.
43

Torque Control of a Permanent Magnet Brushless DC Machine for a Hybrid Electric Vehicle

Salgues, Christophe Xavier 02 September 2008 (has links)
No description available.
44

Context-driven agents in computer supported cooperative works

Lichtman, Brian D. 01 December 2011 (has links)
This thesis describes a research project that investigates the level of contextualization needed to successfully build context-driven agents that can manage a cooperative project. Many times in industry, collaborators in a large project may be located vast distances from each other. It is for this reason that management of such projects can often be difficult. The purpose of this research is to design an agent that can take on the role of a project manager (PM) to assist the human project manager. Specifically, this thesis looks to give such project management agents full situational awareness. It is hypothesized that only with situational awareness can an agent successfully act in the role of a project manager. This thesis describes the investigation into the use of Context-Based Reasoning and Contextual Graphs to create an agent with such situational awareness. This thesis shows that with enough situational awareness, an agent will have the ability to successfully take on the role of a project manager. In particular, this thesis looks at a PM-agent that can manage a simulated project to design and construct a small sounding rocket.
45

Adaptive Digital Predistortion with Applications for LMDS Systems

Johnson, Daniel Eric 29 September 2000 (has links)
A limiting factor in the widespread deployment of LMDS systems is the limited distance of current systems. Rain attenuation and limited transmitter power are the primary causes of the limited distance. Adaptive digital predistortion is presented as a method of increasing effective transmitter power. A background on LMDS link design, non-linear amplification, and predistortion is presented to assist the reader. A developed simulation uses AM-AM and AM-PM characteristics obtained from laboratory measurements of a 28 GHz amplifier to determine the effect of several predistortion implementation options and to confirm the feasibility of the proposed architecture. The potential impact of this predistortion architecture on LMDS system design is considered. The presented multi-stage predistortion architecture is found to be capable of implementation at Msymbol/second rates utilizing a FPGA or custom IC and a moderate speed digital signal processor. / Master of Science
46

Carbothermic reduction of oxides during nitrogen sintering of manganese and chromium steels.

Mitchell, Stephen C., Cias, A. January 2004 (has links)
No / To interpret nitrogen sintering of chromium and manganese steels without the formation of deleterious oxides, but with manganese and carbon the formation of deleterious oxides, but with manganese and carbon modifying the local microclimate, the role of the volatile Mn and modifying the local microclimate, the role of the volatile and Mn carbothermic reactions were considered. carbothermic reactions were considered. Reduction of Cr Reduction of Cr 2 2 O About 3 3 by Mn vapour by Mn vapor is always favourable. is always favorable. CO is an effective reducing agent, however, whereas CO is an effective reducing agent, however, whereas at atmospheric pressure it will reduce FeO at730°C, temperatures some at atmospheric pressure it will reduce FeO at730 ° C, temperatures some 500 and 700°C higher, ie above those for conventional sintering, are 500 and 700 ° C higher, ie above those for conventional sintering, are necessary for reducing Cr necessary for reducing Cr 2 2 O About 3 3 and MnO, respectively. and MNO, respectively. Accordingly partial Accordingly partial pressures must be considered and the sintering process is modelled at a pressures must be considered and the sintering process is modeled at a conglomerate of several surface oxidised alloy particles surrounding a pore conglomerate of several surface oxidised alloy particles surrounding a pore with graphite present and a tortuous access to the nitrogen-rich atmosphere with graphite and present a tortuous access to the nitrogen-rich atmosphere containing some water vapour and oxygen. containing some water vapor and oxygen. The relevant partial pressures The relevant partial pressures were calculated and reduction reactions become thermodynamically were calculated and reduction reactions become thermodynamically favourable from 200°C. favorable from 200 ° C. Kinetics, however, dictates availability of CO and Kinetics, however, dictates availability of CO and the relevant reactions are the water-gas, C + H the relevant reactions are the water-gas, C + H 2 2 O = CO + H O = CO + H 2 2 from 500°C from 500 ° C and the Boudouard, C + CO and the Boudouard C + CO 2 2 = 2CO, from 700°C. = 2CO, from 700 ° C. Discussion of sintering Discussion of sintering mechanisms is extended to processing in semi-closed containers, also mechanisms is extended to processing in a semi-closed containers, also possessing specific microclimates.
47

Field application of the PM Device and assessment of early age behaviors of cement stabilized pavement layers

Sullivan, William Griffin 30 April 2021 (has links)
Cement stabilized material used for subbase or base pavement layers has been a widely accepted practice by many state Departments of Transportation (DOTs); particularly, for DOTs with limited access to quality crushed aggregates for pavement construction. Despite over 100 years of use, construction specifications governing cement stabilized pavement layers have largely remained the same and are primarily method based specifications (i.e. individual components evaluated and construction methods prescribed) rather than evaluating or testing mechanical properties of the end product. With the recent emergence of the Plastic Mold compaction Device (PM Device), multiple agencies are looking to depart from method based soil-cement specifications by implementing the PM Device for design and construction quality control and quality assurance (QC/QA) testing. Prior to this dissertation, PM Device protocols have been validated under lab conditions but only limited field validation had been performed. Additionally, time delay between initial mixing and compaction of cement stabilized soils is a known issue, which can affect compaction of PM Device specimens as well as construction target density values determined through AASHTO T134 Proctor testing. The main objectives of this dissertation are to investigate time delay effects on cement stabilized soil compactability during Proctor testing, develop a nationally recognized Standard Practice for PM Device specimen fabrication, and perform PM Device field evaluations for QC/QA testing. Lab experiments were conducted to investigate time delay effects and finalize PM Device Standard Practice protocols. Five field projects were evaluated to validate PM Device QC/QA applications and Standard Practice protocols in a construction environment. Time delay was observed to have a notable detrimental influence on compactability during AASHTO T134 Proctor testing and PM Device specimen fabrication. Recommended guidance was provided to characterize compaction delay effects. AASHTO PP92-19 was developed and published by AASHTO's Committee on Materials and Pavements to standardize specimen fabrication for the 3x6 inch and 4x8 inch versions of the PM Device. The PM Device fared well for construction activities when benchmarked relative to density, strength, and modulus of cores taken from constructed cement stabilized pavement layers. The PM Device was recommended for implementation consideration by state DOTs and other agencies.
48

Carbothermic reduction of oxides during nitrogen sitnering of manganese and chromium steels

Mitchell, Stephen C., Cias, A. January 2004 (has links)
Yes / To interpret nitrogen sintering of chromium and manganese steels without the formation of deleterious oxides, but with manganese and carbon modifying the local microclimate, the role of the volatile Mn and carbothermic reactions were considered. Reduction of Cr2O3 by Mn vapour is always favourable. CO is an effective reducing agent, however, whereas at atmospheric pressure it will reduce FeO at ~730°C, temperatures some 500 and 700°C higher, i.e. above those for conventional sintering, are necessary for reducing Cr2O3 and MnO, respectively. Accordingly partial pressures must be considered and the sintering process is modelled at a conglomerate of several surface oxidised alloy particles surrounding a pore with graphite present and a tortuous access to the nitrogen-rich atmosphere containing some water vapour and oxygen. The relevant partial pressures were calculated and reduction reactions become thermodynamically favourable from ~200°C. Kinetics, however, dictates availability of CO and the relevant reactions are the water-gas, C + H2O = CO + H2 from ~500°C and the Boudouard, C + CO2 = 2CO, from ~700°C. Discussion of sintering mechanisms is extended to processing in semi-closed containers, also possessing specific microclimates.
49

Design and processing of low alloy high carbon steels by powder metallurgy : P/M processing and liquid phase sintering of newly designed low-alloy high carbon steels based on Fe-0.85Mo-C-Si-Mn with high toughness and strength

Abosbaia, Alhadi Amar Salem January 2010 (has links)
The work presented has the ultimate aim to increase dynamic mechanical properties by improvements in density and optimisation of microstructure of ultra high carbon PM steels by careful selection of processes, i.e. mixing, binding, alloying, heating profile and intelligent heat treatment. ThermoCalc modelling was employed to predict liquid phase amounts for two different powder grades, Astaloy 85Mo or Astaloy CrL with additive elements such as (0.4-0.6wt%)Si, (1.2-1.4wt%)C and (1-1.5wt%)Mn, in the sintering temperature range 1285-1300ºC and such powder mixes were pressed and liquid phase sintered. In high-C steels carbide networks form at the prior particle boundaries, leading to brittleness, unless the steel is heat-treated. To assist the breaking up of these continuous carbide networks, 0.4-0.6% silicon, in the form of silicon carbide, was added. The water gas shift reaction (C + H2O = CO + H2, start from ~500ºC) and Boudouard reaction (from ~500ºC complete ~930ºC) form CO gas in the early part of sintering and can lead to large porosity, which lowers mechanical properties. With the use of careful powder drying, low dew point atmospheres and optimisation of heating profiles, densities in excess of 7.70g/cm3 were attained. The brittle microstructure, containing carbide networks and free of cracks, is transformed by intelligent heat treatment to a tougher one of ferrite plus sub-micron spheroidised carbides. This gives the potential for production of components, which are both tough and suitable for sizing to improve dimensional tolerance. Yield strengths up to 410 MPa, fracture strengths up to 950 MPa and strains of up to 16 % were attained. Forging experiments were subsequently carried out for spheroidised specimens of Fe-0.85Mo+06Si+1.4C, for different strain rates of 10-3, 10-2, 10-1 and 1sec-1 and heated in argon to 700ºC, density ~7.8g/cm3 and 769 MPa yield strength were obtained.
50

"Aldrig skada, om möjligt bota, ofta lindra, alltid trösta" : riktlinjer/PM smärtbedömning och behandling

Fastling, Charlotta, Karlsson, Madelene January 2011 (has links)
Syftet med denna studie var att beskriva riktlinjer och PM angående smärtbedömning och behandling som finns att tillgå på olika akutmottagningar och sjukhus. Smärta är en av de vanligaste orsakerna till att människor söker sjukvård i Sverige, därför ställer detta krav på sjukvårdens kompetens och tillgänglighet till riktlinjer/ PM som stödjer den vård som ges. En förfrågan om att få ta del av sjukhusens riktlinjer/ PM skickades via ut mail. Dokumenten analyserades och innehållet delades därefter in i sju kategorier som beskrev dess kontext, Definition av smärta, Bedömning/ Skattning av smärta, Behandling, Mål, Utvärdering/ Dokumentation, Smärtombud och Övrigt. I kategorin övrigt tas bland annat den bristande referenshanteringen till riktlinjer/ PM upp. Dokumenten visade en stor variation gällande innehåll och utförande. För att säkerställa en trygg och säker vård av god kvalitet krävs evidensbaserad kunskap, en kunskap som kontinuerligt skall uppdateras och förnyas. Något som sjukhusen enligt lagstiftning har skyldighet att göra. / The purpose of this study was to describe guidelines/ PM regarding pain assessment and treatment that is available in various emergency rooms and hospitals. Pain is one of the most common reasons for seeking medical care in Sweden, therefore medical expertise is required and also access to guidelines/ PM that supports the care provided. A request was sent by email to the hospitals requesting access to their guidelines/ PM. The contents of the documents were analyzed using seven categories which describe its context. Definition of pain, Assessment / Measurement of pain, Treatment, Goals, Evaluation / Documentation, Pain and Other Outlets. The category other outlets include amongst others the lack of reference to the management guidelines / PM. The results showed that the documents varied greatly with respects to content and design. To ensure safe and high quality care, evidence-based knowledge is required, knowledge that is constantly updated and renewed. This is something which Swedish hospitals have a legal obligation to perform.

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