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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.
161

Industrial Pilot Scale Leaching and Recovery of Zinc from Waste-to-Energy Fly Ash using Scrubber Liquids

Wagner, Manuela January 2016 (has links)
Previous studies from laboratory experiments and a similar process at a plant in Switzerland, led to the pilot plant project at Renova AB, which will be described in this master thesis. In cooperation with Götaverken Miljö AB it was investigated if fly ash, produced at the Renova Waste-to-Energy plant in Gothenburg, could be treated with own scrubber liquids in order to recover zinc. If successful, Renova might build this tested pilot process in to a big scale. The pilot plant has a scale of 16 times smaller than a future big scale process. The goal of the project is to leach zinc from fly ash and gain a fly ash residue, which is classified as non-hazardous waste. The filtrate from the leaching campaign is treated so that the containing zinc is recovered. The zinc cake end product shall has a quality so that it can be sold to other industries or upgraded to high purity zinc metal. The evaluation of the experiments showed that the pilot plant process was successful. It was possible to leach out zinc by a maximum quote of 74%. The total recovery of zinc could be achieved by a maximum of 72%. The final zinc cake product was achieved through a precipitation and filtration campaign. This thesis evaluates, which process set-ups for zinc recovery through leaching and precipitation & filtration are the best and can be recommended for a big scale process. In addition, it briefly analyses the zinc product quality. Future studies will be necessary within: cost analysis of the process, zinc product quality and an analysis of the ash residue.
162

Bärgning av medvetslösa eller svårt skadade : En inledande kartläggning över bärgningssystem med efterföljande intervjuer av lotsar och båtmän

Ekman, Johan, Strindin, Mikael January 2016 (has links)
Sjöfartsverket är idag huvudansvarigt för all sjöräddning i Sverige där lotsbåten är ett av de fartyg som deltar. Det nuvarande systemet för bärgning anses dock ha vissa brister beträffande räddning av personer som i vattnet är medvetslösa eller svårt skadade. Syftet med studien var att efter en inledande kartläggning av olika system för bärgning av medvetslösa eller svårt skadade personer, undersöka vad besättningsmän från Sjöfartsverkets lotsbåtar anser om systemen samt svårigheterna vid bärgning. I intervjuerna framkom det att dagens system varken är byggt för övning eller för räddning av någon som är medvetslös eller svårt skadad. Resultatet visar även att rådande väderförhållanden samt tiden är avgörande faktorer för en lyckad räddning. Majoriteten av besättningsmännen anser att ett system placerat i aktern tillsammans med det nuvarande systemet är den kombination av system som skulle kunna göra räddningsarbetet ombord på lotsbåtarna både enklare och effektivare. / The Swedish Maritime Administration is today the authority with the main responsibility inSweden regarding search and rescue where the pilot boat is one of the vessels involved.However, the current system of salvage is considered to have some deficiencies regarding therescue of persons from the water whom are unconscious or severely injured. The purpose of this study was that after an initial survey of the different systems for rescuing unconscious or severely injured people, examine what crew members from the Swedish Maritime Administrations pilot boats thinks about the systems and the difficulties surrounding the salvage. The interviews revealed that today's current system is not built to be practiced with orfor the rescue of someone who is unconscious or badly injured. The investigation also shows that the prevailing weather conditions and time are crucial factors for a successful rescue. The majority of the crewmembers consider that a system located in the stern with today's existing system is the combination of systems that could make the rescue work aboard the pilot boats easier and more efficient.
163

Autonomous flight of a model aircraft

Peddle, Iain K. 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2005. / The successful development of a conventional flight autopilot for a model aircraft is presented. All aspects of the autopilot design are considered, from modeling to flight tests. A mathematical aircraft model, as a function of the aircraft’s physical parameters alone, is presented. A controller architecture capable of regulating the motion variables required for conventional flight using only low cost, off-the-shelf sensors is developed. The controller design complements the aircraft model development technique used, by reducing the sensitivity of the controller performance to the model accuracy. The avionics and ground station design is presented. The avionics includes a generic Inertial Measurement Unit (IMU). The total avionics cost is only R5000. Results from three days of flight tests demonstrate the autopilot’s success. Its rapid success can largely be attributed to the extensive simulations of the entire autopilot in the two non-linear simulators developed.
164

From torrefaction to gasification : Pilot scale studies for upgrading of biomass / Från torrefiering till förgasning : Experiment i pilotskala för förädling av biomassa

Strandberg, Martin January 2015 (has links)
Increasing the share of biomass, preferably by replacing fossil fuels, is one way to mitigate the present climate change. Fossil coal can be directly replaced by co-combustion of coal and biomass and fossil engine fuels (gasoline and diesel) could potentially partly be replaced by synthetic renewable fuels produced via entrained flow gasification of biomass. The use of biomass in these processes is so far limited, partly because of the fibrous and hygroscopic nature of biomass which leads to problem in storing, transportation, handling and feeding. This thesis demonstrates how the challenging characteristics of raw biomass are mitigated by the pretreatment method torrefaction. Torrefaction is a process where biomass is heated in an oxygen deficient atmosphere to typically between 240 and 350°C for a time period of 2 minutes to 1 hour. Most of the torrefaction R&D in the literature have so far been performed with bench-scale batch reactors. For the purpose of carefully studying continuous torrefaction, a 20 kg/h torrefaction pilot plant was therefore designed, constructed and evaluated. The overall conclusion from this thesis is that the many benefits of torrefied biomass are valid also when produced with a continuous pilot plant and for typically Swedish forest biomasses. Some of the documented improved biomass properties are increased heating value, increased energy density, higher friability (lower milling energy) and less hydrophilic biomass (less moisture uptake). Most of the improvements can be attributed to the decomposition of hemicellulose and cellulose during torrefaction. The most common variables for describing the torrefaction degree are mass yield or anhydrous weight loss but both are challenging to determine for continuous processes. We therefore evaluated three different methods (one existing and two new suggestions) to determine degree of torrefaction that not require measurement of mass loss. The degree of torrefaction based on analyzed higher heating value of the raw and torrefied biomass (DTFHHV) predicted mass yield most accurate and had lowest combined uncertainty. Pelletizing biomass enhance transportation and handling but results from pelletization of torrefied biomass is still very limited in the literature and mainly reported from single pellet presses. A pelletization study of torrefied spruce with a ring die in pilot scale was therefore performed. The bulk energy density was found to be 14.6 GJ/m3 for pelletized torrefied spruce (mass yield 75%), a 40% increase compared to regular white pellets and therefore are torrefied pellets more favorable for long distance transports. More optimization of the torrefied biomass and the pelletization process is though needed for acquiring industrial quality pellets with lower amount of fines and higher pellet durability than attained in the present study. Powders from milled raw biomass are generally problematic for feeding and handling and torrefied biomass has been proposed to mitigate these issues. The influence of torrefaction and pelletization on powder and particle properties after milling was therefore studied. The results show that powder from torrefied biomass were enhanced with higher bulk densities, lower angle of repose as well as smaller less elongated particles with less surface roughness. Even higher powder qualities were achieved by pelletizing the torrefied biomass before milling, i.e. another reason for commercial torrefied biomass to be pelletized. Entrained flow gasification (EFG) is a promising option for conversion of biomass to other more convenient renewable energy carriers such as electricity, liquid biofuels and green petrochemicals. Also for EFGs are torrefied fuels very limited studied. Raw and torrefied logging residues were successfully gasified in a pilot scale pressurized entrained flow biomass gasifier at 2 bar(a) with a fuel feed corresponding to 270 kWth. Significantly lower methane content (50% decrease) in the syngas was also demonstrated for the torrefied fuel with mass yield 49%. The low milling energy consumption for the torrefied fuels compared to the raw fuel was beneficial for the gasification plant efficiency.
165

Effects of ozonation/filtration on the raw water from Lake Mälaren / Effekter av ozonering/filtrering på råvattnet från sjön Mälaren

Larsson, Nina January 2004 (has links)
<p>Syftet med examensarbetet var att undersöka effekterna av ozonering och filtrering på råvattnet från sjön Mälaren. Studien är utförd i en pilotanläggning på Lovö vattenverk, Stockholm Vatten AB, under våren 2004.</p><p>En negativ effekt med den konventionella reningen är den stora konsumtionen av kemiska koagulanter. Kemikalieanvändningen leder till många transporter och processen producerar också ett slam som för närvarande transporteras till Mälaren. År 2001 byggdes en pilotanläggning på Lovö vattenverk för utveckling av nya processer, en av processerna är ozonering följt av olika filter.</p><p>Ozonering har använts i Europa i många år som desinfektion i slutet av dricksvattenreningsprocessen. Intresset för ozonering har ökat markant sista åren och idag används ozonet också i andra steg i processen. Förutom desinfektion har ozonet andra fördelar, som oxidation av järn och magnesium, mikroflockning, reduktion av lukt och smak samt är bra på att reducera färgen på vattnet. Mikroflockningen leder till att kemikalieanvändningen kan minska och i vissa fall tas bort helt.</p><p>Den här studien startade med en litteraturundersökning följd av försök med ozonering och filtrering i pilotanläggningen. De första undersökningarna sammanfattades med att ozonering följt av filtrering inte gav tillräckligt bra resultat och processen behöver ett komplement för att producera ett högklassigt vatten.</p><p>Undersökningen fortsatte med laboratorieanalyser för att undersöka effekterna av olika kemiska koagulanter. Resultatet visade att järnsulfat tillsammans med kalcium var ett bra alternativ och en lägre kemikaliedos kunde användas.</p><p>Efter implementering av kalcium och järnsulfat till pilotanläggningen testades olika ozondoser och olika järnsulfatdoser. Det bästa resultatet erhölls då man använde sig av en ozondos på 6 mg O3/l och en järnsulfatdos på 50-60 μmol/l. Denna mängd av järnsulfat är ca 60 % lägre än den dos som används vid den konventionella reningen på Lovö vattenverk.</p><p>Olika filter används i pilotanläggningen och för att förbättra resultatet provades även ett Filtralite-filter som biofilter istället för GAC-filtret. Jämförelsen mellan Filtralite-filter och GAC-filter visade på stora skillnader i parametervärden i början av studietiden. När bakteriepopulationen ökade i Filtralite-filtret blev skillnaderna mindre och i slutet av undersökningstiden var parametervärdena likartade. Det slutliga resultatet indikerar att Filtralite-filter kan vara ett bra alternativ som biofilter.</p> / <p>This Master thesis was made to investigate the effects of ozonation and filtration on raw water from Lake Mälaren. The study was performed in lab-scale as well as in a pilot plant at Lovö waterworks, Stockholm Water Company during spring 2004.</p><p>The conventional treatment at Lovö waterworks comes with a few disadvantages, such as large consumption of chemical coagulants. The chemical consumption leads to many transports and the treatment also produces a sludge which is, in present, returned to Lake Mälaren. In 2001 a pilot plant were built at Lovö waterworks for research on new treatment processes, and ozonation followed by filtration is one of them.</p><p>Ozonation has been used in Europe for several years as disinfection at the end of the drinking water treatment process. The interests of ozonation has increased significantly in recent years and today the ozonation is used in other steps in the drinking water treatment process. Except for the disinfection, ozone has other benefits such as oxidation of iron and manganese, microflocculation, reduction of taste and odour and it is also effective to reduce the water colour. The microflocculation leads to the fact that less or no coagulants need to be used in the process.</p><p>This study started with a literature overview followed by experiments on ozonation and filtration in the pilot plant. After the first experiments the conclusions were that the ozonation and filtration did not reach the same results as Lovö waterworks. To continue, jar tests were made to see the effects of different coagulants. The result indicated that ferric sulphate together with calcium addition (pH-adjustment) was a good alternative. Thereby a lower coagulant dose could be used.</p><p>When ferric sulphate and calcium were implemented into the pilot plant, different ozone doses and ferric sulphate doses were tested. The best results occurred when an ozone dose of 6 mg O3/l and a ferric sulphate dose of 50-60 μmol/l were used. This amount of ferric sulphate is approximately 60 % lower than that for the conventional treatment at Lovö waterworks. To produce ozone electrons are needed and energy consumption increases with approximately 66 % compared to the conventional treatment. The decrease in chemical dose and increase in energy demand gives a decrease of the total cost with 10 % compared to the conventional treatment. The results indicate that the treatment with ozonation, calcium addition and ferric sulphate as a coagulant is an alternative to the conventional treatment.</p><p>Different filters were used in the pilot plant and to improve the results a Filtralite-filter was tested instead of the GAC-filter as a bio filter. When comparing Filtralite-filter with the GAC-filter there were large differences between the filters at the beginning of the study. When the bacteria population in the Filtralite-filter had started to increase the differences became less. In the end of the experimental period the filters had similar conditions and Filtralite-filter may be a good alternative as a biofilter.</p>
166

Kommunicera säkert : En studie om kommunikation mellan lotsar, befälhavare och bogserbåtsbefälhavare

Adriansson, Mikael, Johansson Breeze, Peter January 2014 (has links)
Syftet med studien var att undersöka vad lotsar, befälhavare och bogserbåtsbefälhavare ansåg om den verbala kommunikationen med hänsyn till säkerhet och effektivitet. Detta eftersom majoriteten av alla fartygsolyckor inträffar på grund av den mänskliga faktorn, där kommunikationen är en stor del. I studien genomfördes semistrukturerade intervjuer med två lotsar, två befälhavare och två bogserbåtsbefälhavare. Genom de sex intervjuerna i studien gick det bland annat att utläsa att användandet av standardfraser och closed loop communication varierar. Om användandet inom dessa två områden blev bättre skulle säkerheten kunna ökas. I studien framkom det också att kunskapen i eng­elska varierar vilket kan leda till missuppfattningar. Bättre kunskap i det engelska språket och hur man kommunicerar kan vara två andra sätt att öka säkerheten. / The aim of this study was to examine how pilots, vessel masters and tugboat masters perceive the importance of verbal communication with consideration to safety and efficiency.  This is based on the fact that the vast majority of accidents involving vessels occur because of human error, where lack of communication plays a large part. In the study semi-structured interviews were held with two pilots, two masters and two tugboat masters. After conducting these six interviews it became apparent at the use of standard phrasing and closed loop communication could vary. Based on the information collected one conclusion is that if the usage within these two areas improved safety could increase. It was also apparent in this study that the knowledge of the English language differed greatly which also could lead to misunderstandings with the giving of instructions. A better proficiency in English and better knowledge of verbal communication could be two possible ways of increasing safety.
167

Criteria for acceptable stick force gradients of a light aeroplane

Bromfield, Michael January 2012 (has links)
During the period 1980 to 2008 there were 359 fatal accidents involving UK registered light aeroplanes of which 36% occurred in visual meteorological conditions. In all, 216 lives were lost with accidents being attributed to the pilot 'failing to maintain proper control resulting in a stall or spin'. Dissimilar fatal stallrelated accident rates are evident for aeroplane makes & models of similar design. During the course of this programme of research, flight testing of two similar aeroplane models using a case study method showed marked differences in the variation of stick force with airspeed or stick force gradient in all flight conditions. This suggested that 'control feel' was a contributory factor towards the pilot’s failure to maintain proper control. Current certification standards for light aeroplanes rely upon the subjective assessment of stick force gradients by test pilots, requiring that substantial changes in airspeed are accompanied by clearly perceptible changes in stick force with no specified minimum gradient. This programme of research has been carried out to determine acceptable criteria for stick force gradients of a light aeroplane in all flight conditions. Criteria has been determined from flight tests of aeroplanes with different in-service safety records and subjective pilot workload assessment using simulated flying tasks with different stick force gradients performed by twenty GA pilots. Simulation tests indicated that pilot mental demand increased significantly (p > 0.05) when stick force gradient was reduced to ‘zero’, representing an aeroplane with neutral longitudinal static stability. A predictive model has been developed to estimate stick force gradients for a light aeroplane in any flight condition under quasi-static, longitudinal, non-manoeuvring flight and 1-g loading conditions. The model builds upon previous published work limited to cruising flight, and enables the estimation of stick forces and gradients due to high lift devices in the climb and landing condition by consideration of the combined effects of wing loading, CG, elevator gearing, flaps and elevator trim setting. Implemented using MATLAB, the model has been validated by comparing with flight test results for the case study aeroplanes and showed mean differences of ±0.025 daN/kt. The predictive model should be used in preliminary aeroplane design to assess tendencies towards neutral stability in high workload, safety critical flight conditions such as the take-off and landing. In addition, the model should be used to analyse existing aeroplanes with comparatively low or neutral stick force gradients in safety critical flight phases and to predict the effects of changing CG and/or flap limits to increase stick force gradient and improve control feel. The combined results of these studies suggest that a minimum acceptable stick force gradient for a non-aerobatic light aeroplane in all flight conditions should be nonzero and between 0.10~0.13 daN/kt. A stable and predictable stick force variation with airspeed will ensure that any substantial deviation from trimmed airspeed is accompanied by a stick force change clearly perceptible to the pilot and also provide additional warning of the proximity to the stall. The use of specific criteria to complement qualitative test pilot opinion, will assist in confirming compliance and provide consistency with current standards for sailplanes/powered sailplanes and large commercial aeroplanes, both of which already have defined minimum acceptable gradients.
168

Support Group at the Border: A Pilot Social Support Program for the Well-Being of Mexican Immigrant Women Residing Near the Southern U.S.-Mexico Border Region

Morales, Stephanie Ruíz, Morales, Stephanie Ruíz January 2017 (has links)
Mexican immigrant women are a vulnerable population group in the U.S., and face challenges as a result of the nation’s anti-immigrant landscape. To help Mexican immigrant women cope with these realities, scholars have proposed the implementation of social support interventions. Yet only two studies have executed social support interventions for immigrant women. Those tailored specifically for Mexican immigrant women are nonexistent. To address this gap, this Master's thesis piloted the first social support intervention for Mexican immigrant women in the U.S. The purpose was to assess the impact of a social support intervention on the perceived social support for Mexican immigrant women. The study (1) surveyed Mexican immigrant women's current perceived social support, (2) investigated whether engaging in a social support intervention could improve Mexican immigrant women's perceived social support, and (3) explored (through the use of a foto novela) the elements (e.g., persons, places) Mexican immigrant women consider to be most important sources of social support in their lives. Surveys were administered pre- and post-intervention assessing perceived social support using three Likert-type scales. At pre-intervention, perceived social support was moderately high. A difference in perceived social support at post-intervention was observed, but without significance. This work adds to the small body of literature on social support interventions for Mexican immigrant women, and has important implications for future interventions and research. This work also documents the use of foto novelas – an innovative tool to engage with (and give a voice to) Mexican immigrant women. Future work should consider the use of foto novelas, as these amplify new understandings of social support, and capture (through the use of photographs) Mexican immigrant women’s own interpretation of social support.
169

De la politique aux changements de pratiques : la traduction du Plan Alzheimer du Québec dans ses formes locales

Guillette, Maxime January 2016 (has links)
En raison d’importantes transitions démographiques et épidémiologiques, le nombre de personnes atteintes de la maladie d’Alzheimer et d’autres troubles neurocognitifs majeurs augmentera rapidement dans les sociétés occidentales. Ces maladies posent des enjeux d’envergure pour les personnes atteintes, leurs proches, les communautés et l’organisation des services. Plus largement, ce sont les politiques publiques qui doivent être repensées. Sous ce principe, le gouvernement du Québec a mobilisé une équipe d’experts pour concevoir le Plan Alzheimer du Québec (PAQ) (2007). La principale stratégie de mise en œuvre qui découle de ce plan fût de soutenir le développement de 19 projets pilotes ayant principalement pour objectif de diagnostiquer plus rapidement les personnes atteintes de ces maladies et de rehausser la qualité de leur suivi, au sein des Groupes de médecines de famille (GMF). Le modèle d’appel à propositions développé par l’équipe ministérielle a convié les acteurs locaux du système sociosanitaire québécois le souhaitant à rédiger une proposition en fonction de leurs propres conditions locales de pratique, bien que la proposition devait globalement être en cohésion avec les priorités nationales. Dû au fait que ce type de stratégie de diffusion des politiques publiques vers les organisations délivrant des services pose des défis d’équilibre entre les priorités ministérielles et les réalités locales, nous nous sommes intéressés à la mise en œuvre du plan québécois. Plus précisément, notre principal but de recherche consistait à comprendre de quelle façon les orientations du PAQ se sont traduites dans les projets pilotes. Pour ce faire, nous avons mené une analyse secondaire de données qualitatives qui s’articule autour de trois stratégies de collecte de données : 1) les documents du ministère et ceux des 19 propositions développées par les acteurs locaux, 2) quatre entretiens semi-dirigés auprès d’acteurs-clefs ayant participé au niveau national à la mise en œuvre du PAQ et 3) 15 groupes de discussions focalisées ayant été réalisés auprès de gestionnaires et de professionnels impliqués au sein des innovations, dont des travailleuses sociales. La mise en œuvre du PAQ vers ses formes locales a donné lieu au développement d’une grande diversité de projets innovants, comprenant principalement des médecins, des infirmières et des travailleuses sociales. La mise en place d’un important dispositif d’accompagnement du changement, lors de l’implantation des innovations, a favorisé des ajustements entre les deux principes en apparences contradictoires que sont le respect des objectifs ministériels et l’encouragement des acteurs locaux à adapter le projet en fonction de leurs réalités. Cet accompagnement, globalement positif, a toutefois été mis en place tardivement, ce qui eut des effets durables sur l’implantation des innovations. Nous soutenons donc que la phase initiale de conception des innovations locales est un moment critique qui requiert d’accompagner les acteurs locaux, afin de clarifier le modèle proposé par la politique publique et favoriser la collaboration des principales personnes qui sont parties prenantes du changement.
170

A Randomized Pilot Trial: An Internet-Based Mind/body Intervention To Mitigate Anxiety In Women Experiencing Infertility

Clifton, Jessica 01 January 2015 (has links)
Infertility is a frequently occurring chronic health condition, which often persists throughout the reproductive years. Heightened anxiety symptoms often are comorbid with infertility diagnoses. Women experiencing infertility, and particularly those with anxiety symptoms, characterize an emerging population that deserves special attention. However, women experiencing infertility have identified barriers to seeking psychotherapy (e.g., fears of being dismissed from fertility treatment and/or stigmatized). Consequently, women diagnosed with infertility need a psychotherapy that not only can reduce these symptoms, but can also be private and convenient. The current study translated an empirically tested in-person mind/body protocol into an internet-based intervention to suit the needs of this population. Seventy-one women were randomly assigned to the intervention or a wait-list control. At the close of the study, only three participants had completed the intervention. At mid-assessment, relative to the wait-list group, the intervention group had a lower level of depressive symptoms and, for those with elevated anxiety symptoms at baseline, a lower level of anxiety symptoms. The findings suggest that even a partially completed internet-based intervention can reduce the anxiety and depressive symptoms of women with a diagnosis of infertility.

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