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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.
71

Synthesis of CdZnS by Chemical Bath Deposition for Thin Film Solar Cells

Fjällström, Emil January 2017 (has links)
The buffer layer is a crucial component in thin film solar cells. Defects at the interface between absorber and buffer layer lead to high recombination rate and the band structure at the interface highly affects the performance of the solar cell. In this thesis a method to synthesize thin films containing cadmium, zinc and sulfur, CdZnS, by chemical bath deposition has been developed and evaluated. A higher current from the device is expected when replacing the common buffer layer cadmium sulfide, CdS, with the more transparent CdZnS. It is also possible that the alternative buffer provides a more favorable energy band alignment at the interface with the absorber Copper-Zinc-Tin-Sulfide (CZTS). The deposition process was developed by studying depositions on glass. Increasing [Zn2+]/[Cd2+] initially led to films with higher band gap (Eg). By varying deposition time the time before colloidal growth became dominant was observed. Addition of triethanolamine showed that triethanolamine binds stronger to zinc ions than to cadmium ions. Two recipes that led to Eg=2.63 eV were evaluated as buffer layer in Copper-Indium-Gallium-Selenide (CIGSe) and CZTS solar cells. The short circuit current of the devices increased in general with the CdZnS buffers compared to CdS. The best CZTS cell with a CdZnS buffer layer had 7.7 % efficiency compared to the 7.5 % reference. For future research it is recommended that the effect of thickness variation and deposition temperature is evaluated and that additional material characterization is performed in order to further understand and develop the deposition method.
72

Obtenção de ligas AuxSny utilizando deposição eletroquímica: influência dos aditivos, análise de morfologia e crescimento de multicamadas. / Plating of AuxSny alloys using electrochemical deposition: influences of additives, morphology analysis and multilayer growth.

Cardoso, Juliana Lopes 25 November 2011 (has links)
Neste trabalho, é apresentado um estudo sobre a influência de aditivos em banhos de eletrodeposição de Au, análise da morfologia dos depósitos de Au e o crescimento de multicamadas da liga AuxSny por deposição eletroquímica. Os banhos de eletrodeposição estudados são baseados em uma composição, comum na literatura, formada por tetraclorourato(III) de potássio (KAuCl4), cloreto de estanho(II) (SnCl2), sulfito de sódio (Na2SO3), e citrato de amônio [(NH4)HC6H5O7]. Os contatos de solda da liga AuxSny, aplicáveis em diversos dispositivos microeletrônicos, podem ser formadas de maneira mais econômica a partir de banhos eletroquímicos. Banhos ácidos e reagentes de baixa toxicidade são exigências comuns dos novos banhos de eletrodeposição. A formação de multicamadas permite, ainda, ampliar o uso do metal de solda em dispositivos sensíveis a altas temperaturas, devido ao baixo ponto de fusão da liga. A obtenção das ligas AuxSny utilizando deposição eletroquímica, foi feita com base no estudo sobre banho de eletrodeposição e seus depósitos, a partir de um banho para deposição da liga AuxSny já conhecido. O aprimoramento do banho de eletrodeposição foi focado no banho de eletrodeposição de Au, com três opções de aditivos, buscando avaliar as características dos depósitos e o tempo de estabilidade do banho. Os aditivos utilizados foram hipofosfito de sódio (NaH2PO2), metanal (HCHO) e tiossulfato de sódio (Na2S2O3), separadamente. Esses banhos foram analisados por voltametria cíclica, e os depósitos obtidos a partir de eletrodeposições foram caracterizados por Espectrometria por Retroespalhamento de Rutherford (RBS), Microscopia Eletrônica de Varredura (SEM) e, em alguns casos, por Espectrometria de Energia Dispersiva de Raios X (EDS). Análises de dimensão fractal e de escalamento dinâmico da rugosidade forneceram detalhes importantes sobre a morfologia superficial dos depósitos. .A adição de Na2S2O3 ao banho permitiu o desenvolvimento de um novo banho de eletrodeposição para a co-deposição de Au AuxSny. O Na2S2O3 atua como um complexante dos íons de Au(I) juntamente com o sulfito de sódio. O emprego de 3 g L-1 de Na2S2O3 evita a degradação do banho durante as eletrodeposições. Finalmente, o estudo da eletrodeposição de multicamadas foi feito por controle do potencial aplicado e por controle da corrente aplicada. As multicamadas obtidas apresentaram camadas da liga AuxSny com a concentração de Sn incorporado, variando entre 6 % e 49 % (em porcentagem atômica). / It is shown in this work a study about the influence of additives in baths for electrodeposition of Au, analysis of morphology of gold deposits and the growth of multilayered AuxSny alloys from improved electrodeposition baths based on a common composition of the literature containing potassium gold(III) chloride (KAuCl4), tin(II) chloride (SnCl2), sodium sulfite (Na2SO3) and ammonium citrate dibasic [(NH4)HC6H5O7]. The AuxSny solders are commonly used in microelectronic devices. These solders can be applied in a number of ways, and electrochemical deposition is an attractive alternative due to the low cost process. Acidic baths and low toxicity reagents are common requirements of new electrochemical baths. The multilayered AuxSny alloys are applicable to temperature sensitive materials due to its reduced melting point temperature. Therefore, the study of electrodeposition of AuxSny alloys began with an already known bath and aiming its improvement. The focus of interest was the gold bath, which received additives to improve control of the deposits and their stability. The additives used were sodium hypophosphite (NaH2PO2), methanal (HCHO) and sodium thiosulfate (Na2S2O3), one of each time. These baths were analyzed by cyclic voltammetry and the deposits obtained from these baths were analyzed by Rutherford Backscattering Spectrometry (RBS), Scanning Electron Microscopy (SEM) and, in some cases, Energy Dispersive Spectrometry (EDS). Fractal dimension and dynamic scaling of the surface width analysis allowed one to quantify the surface morphology details. The addition of Na2S2O3 to the bath allowed the development of a new electrodeposition bath for co-deposition of AuxSny. The Na2S2O3 acts as complexing agent of Au(I) ions together with sodium sulfite. The use of 3 g L-1 of Na2S2O3 avoids bath degradation during the electrodepositions. Potential-controlled and current-controlled electrodepositions were employed to obtain multilayers of AuxSny alloys. The multilayer deposits obtained presented between 6 atomic % and 49 atomic % of tin.
73

Développement d’un système de mesure directe du débit d’émission de sources neutroniques / Development of a direct measurement system for the standardization of neutron emission rates

Ogheard, Florestan 11 September 2012 (has links)
La méthode de mesure de référence du débit d’émission de sources neutroniques se fonde sur la technique du bain de manganèse. Elle est destinée à étalonner des sources de neutrons utilisant des radionucléides (241AmBe, 239PuBe, 252Cf,…) en termes de débit d’émission neutronique sous 4π sr. Ce dispositif est complété par un banc de mesure de l’anisotropie d’émission utilisant un support rotatif et un compteur long de type BF3. La source à mesurer est immergée dans une solution de sulfate de manganèse et les neutrons émis sont capturés par les constituants du bain. Dans une configuration classique (sphère de bain de manganèse de 1 m de diamètre et solution concentrée), environ la moitié de ces neutrons conduisent à la création de 56Mn par réaction (n, γ) sur 55Mn. Le radionucléide 56Mn a une période radioactive d’environ 2,6 heures et le bain de manganèse atteint son activité de saturation en 56Mn quand le nombre d’atomes radioactifs créés par unité de temps devient égal au nombre d’atomes se désintégrant pendant ce même temps. Le débit d’émission de la source peut alors être déduit de l’activité en 56Mn de la solution à saturation, via une modélisation ad hoc des réactions nucléaires se produisant dans le bain. Cette installation a été récemment rénovée au LNE-LNHB afin de respecter les règles de sécurité et de radioprotection en vigueur. Cette rénovation a été l’occasion de moderniser et de remettre à niveau les méthodes de mesure et de modélisation du bain et d’entreprendre une étude sur le développement d’un détecteur original pour la mesure directe en ligne de l’activité du manganèse. Ce détecteur est fondé sur la méthode de mesure par coïncidences β-γ. La voie bêta est constituée de deux photomultiplicateurs permettant de détecter l’émission de lumière due à l’effet Cerenkov et la voie gamma utilise un détecteur à scintillateur solide. L’intérêt de cette méthode de mesure est qu’elle permet d’avoir accès à l’activité du bain sans nécessiter d’étalonnage préalable, contrairement à la méthode classique qui utilise un compteur gamma et nécessite la fabrication d’une source de haute activité. Le principe de mesure a été validé à l'aide d'un prototype de détecteur et d'une modélisation effectuée à l'aide du code de calcul stochastique GEANT4. Le détecteur définitif a été réalisé et les mesures obtenues ont été comparées à celles données par une méthode primaire présente au laboratoire. Par ailleurs, des modélisations du bain de manganèse effectuées sous GEANT4, MCNPX et FLUKA, ont été comparées afin de choisir le code le plus fiable. Cette comparaison a permis d'identifier des lacunes notamment dans le code GEANT4 ainsi que des facteurs d'incertitude nécessitant une attention particulière, tels que la modélisation de l'émission neutronique et le choix des sections efficaces. Enfin, un étalonnage de source neutronique a été réalisé grâce à la méthode Cerenkov-gamma et aux facteurs correctifs donnés par la nouvelle modélisation du bain sous MCNPX. Ces mesures ont été complétées dans le cadre d'une comparaison comprenant également des mesures par l'ancienne méthode après étalonnage du couple bain/détecteur par irradiation d'une cible de manganèse en réacteur. Au terme de cette étude, plusieurs voies d'améliorations ont été proposées, dont certaines font déjà l'objet de travaux au LNHB. / The manganese bath technique is the reference method for neutron source emission rates calibration. It is used to calibrate neutron sources using radionuclides (AmBe, PuBe, 252Cf,…) in terms of neutron emission rate under 4π sr. As a complement to this technique, the anisotropy of the source is measured using a rotating source holder and a neutron long counter. The neutron source to be measured is immersed in a manganese sulphate solution whereby the emitted neutrons are captured within the bath contents. In a typical configuration (a 1m diameter sphere and a concentrated solution), approximately half of the neutrons lead to the creation of 56Mn via the 55Mn(n, γ) capture reaction. The 56Mn radionuclide has a half-life of approximately 2.6 hours and the bath reaches saturation when the number of nuclei decaying is equal to the number of nuclei created per unit time. The neutron emission rate from the source can then be deduced from the 56Mn activity at saturation, assuming proper modelling of the nuclear reactions occuring in the bath. The manganese bath facility at LNE-LNHB has been recently refurbished in order to comply with appropriate safety and radioprotection regulations. This has lead to the upgrading of both the measurement methodology and the modelling of the bath, and a study on the development of a new detector for the on-line measurement of the manganese activity was started. This new detector uses the β-γ coincidence measurement method. The bêta channel consists of two photomultipliers tubes which allow the detection of Cerenkov light, and the gamma channel uses a solid scintillation detector. The advantage of this measurement method is that it allows the determination of the bath activity without any prior calibration, unlike the former method which uses a gamma-ray detector calibrated using a high activity manganese source. The principle of the Cerenkov-gamma coincidence measurement has been validated by a prototype of the detector and via modelling of the system using the stochastic transport code GEANT4. The final detector has also been made and the results obtained have been compared to those from a primary measurement method already in use at LNE-LNHB. Furthermore, a comparison of the results from modelling the manganese bath with GEANT4, MCNPX and FLUKA have been undertaken to find the most reliable code. This comparison lead to the identification of various weaknesses, particularly in GEANT4, and several uncertainty factors, such as the modeling of the neutron emission and the choice of the cross-section library. Finally, neutron source calibration has been carried out with the Cerenkov-gamma method and the correction factors given by the new modeling of the bath using MCNPX. These results have been complemented with a comparison with the former method simultaneously undertaken, after calibration of the detector in the bath using a 56Mn source irradiated in a nuclear reactor. At the end of this study, several improvements have been proposed, from which a number are currently under development at LNE-LNHB.
74

Older Adults Perspectives of Bed Bathing

Sumner, Nikki D, Hall, Katherine C, PhD 01 December 2016 (has links)
The purpose of this qualitative pilot study is to explore the patient perspectives about what it is like to receive a bed bath. Examining studies of bath basins versus alternative methods has shown a decrease in the spread of nosocominal infections. However, there is not sufficient evidence evaluating the patient perspectives of assistive bed bathing and interactions with nurses and nursing support staff. This information can provide healthcare providers, especially nurses, with a better understanding of patient perspectives and values. It also supports the national healthcare approach towards patient-centered care.
75

Elaboration, characterization and design of ZnS thin films for optoelectronic applications / Synthèse et caractérisation de couches minces de sulfure de zinc : applications physiques et simulations numériques

Jrad, Abdelhak 17 July 2017 (has links)
Le sulfure de zinc est l'un des premiers semiconducteurs découverts. Il a un grand potentiel d’applications grâces à ses propriétés physicochimiques. Il est intensément utilisé dans des applications optoélectroniques, photocatalytiques et pour la détection de gaz. En particulier, il est utilisé pour des applications photovoltaïques. Dans ce contexte, nous avons commencé par l’étude de l’effet du dopage par des métaux de transition (manganèse, cobalt et cuivre) sur les propriétés structurales, microstructurales, morphologiques, optiques, électriques et magnétiques des couches minces de sulfure de zinc préparées par la technique de dépôt chimique en solution (chemical bath deposition (CBD)) par diffraction aux rayons X, spectroscopie photoélectronique X, spectroscopie Raman, spectroscopie infrarouge, microscopie électronique à balayage, spectrophotométrie UV-Vis-NIR, effet Hall et SQUID. En second lieu nous avons étudié l’effet de la variation de l’épaisseur des couches formant la cellule photovoltaïque à base de Cu(In,Ga)Se2 par la simulation numérique à deux dimensions sous éclairement AM1.5 de puissance 100 mW/cm2 effectué sous Silvaco ATLAS / Zinc sulfide is one of the first semiconductors discovered. It has great potential application thanks to its physicochemical properties. It is used extensively in optoelectronic, photocatalytic and gas detection applications. In particular, it is used for photovoltaic applications. In this work, the effect of doping by transition metals (manganese, cobalt and copper) on the structural, microstructural, morphological, optical, electrical and magnetic properties of zinc sulfide thin films prepared by chemical bath deposition (CBD) technique are studied by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, infrared spectroscopy, scanning electron microscopy, UV-VIS-NIR spectrophotometry, Hall effect and SQUID. The modeling and optimization of higher efficiency Cu(In,Ga)Se2 solar cells are also investigated in this thesis for various layers thickness by using Silvaco ATLAS
76

Explorations of Women's Narrative Agency in Chaucer's Canterbury Tales

Garcia, Mariechristine 01 January 2019 (has links)
This paper explores the extent to which the female characters in Chaucer’s Canterbury Tales exercise any degree of narrative agency. Using both literary and historical approaches, this paper specifically discusses the cases of three of Chaucer’s women: Virginia, Griselda, and the Wife of Bath.
77

Omstruktureringar vid VD-byte / Restructuring at the CEO-change

Orhan, Banu, Ali Hussein, Samir January 2009 (has links)
<p><strong>Objective</strong>: The aim of this paper is to see if there are higher restructuring expenses under the item provision for the first year when a new president takes office.</p><p><strong>Method:</strong> The study was done by a quantitative study. Financial statements have been examined for companies listed on the OMX Stockholm Stock Exchange, Large Cap. We have examined all the companies’ annual reports between the years 2002-2008. We have looked at the experience of restructuring and other expenses that occur in the context of CEO change. In addition, a student t-test done to see whether a link exists between increased restructuring and CEO replacement.</p><p><strong>Results and Conclusion:</strong> The survey shows that there is no fixed happy that there are more restructurings in the item provision for the first year when a new president takes office. Therefore, we cannot be based on the survey results give us that Big Bath Accounting exists among companies listed on the OMX Stockholm Exchange Large Cap, and this in the post restructuring of CEO replacement.</p><p><strong>Draft implicitly Research:</strong> An interesting research could be tested taking into account parameters other than restructuring to investigate the existence of Big Bath Accounting. Examples of these parameters can be depreciation of assets. Another interesting research would be conducted by examining all the OMX Stockholm Stock Exchange. And divide companies sect oral and thus see if the phenomenon Big Bath is more prevalent in certain types of industry.<strong> </strong></p><p><strong> </strong></p><p><strong></strong> </p>
78

Goodwill Accounting : Analyserat utifrån olika teoretiska perspektiv

Ghajar, Homa, Nielsen, Johannes January 2009 (has links)
No description available.
79

Omstruktureringar vid VD-byte / Restructuring at the CEO-change

Orhan, Banu, Ali Hussein, Samir January 2009 (has links)
Objective: The aim of this paper is to see if there are higher restructuring expenses under the item provision for the first year when a new president takes office. Method: The study was done by a quantitative study. Financial statements have been examined for companies listed on the OMX Stockholm Stock Exchange, Large Cap. We have examined all the companies’ annual reports between the years 2002-2008. We have looked at the experience of restructuring and other expenses that occur in the context of CEO change. In addition, a student t-test done to see whether a link exists between increased restructuring and CEO replacement. Results and Conclusion: The survey shows that there is no fixed happy that there are more restructurings in the item provision for the first year when a new president takes office. Therefore, we cannot be based on the survey results give us that Big Bath Accounting exists among companies listed on the OMX Stockholm Exchange Large Cap, and this in the post restructuring of CEO replacement. Draft implicitly Research: An interesting research could be tested taking into account parameters other than restructuring to investigate the existence of Big Bath Accounting. Examples of these parameters can be depreciation of assets. Another interesting research would be conducted by examining all the OMX Stockholm Stock Exchange. And divide companies sect oral and thus see if the phenomenon Big Bath is more prevalent in certain types of industry.
80

Big Bath Accounting

Baryauno, Linda, Pektas, Funda January 2013 (has links)
Bakgrund och problem: Alla börsnoterade företag är, sedan år 2005, tvungna att följa IFRS/IASB riktlinjer för att sammanställa en årsredovisning. IFRS är ett regelverk som tillämpas i alla länder inom Europeiska Unionen. I dessa förpliktelser och riktlinjer finns det kryphål som ger företagen möjlighet till subjektiva bedömningar. De subjektiva bedömningarna ger företagen möjligheten att manipulera redovisningen, detta kallas för Earnings management. I samband med övergången till IFRS medförde det förändringar i hur företagen redovisade. En av förändringarna var att den årliga avskrivningen av goodwill inte längre skulle skrivas av, utan varje år skall företagen göra en prövning om det föreligger ett nedskrivningsbehov av goodwill. Prövningen ger företaget möjlighet att lägga in sina subjektiva bedömningar utifrån eget intresse och därmed kunna manipulera redovisningen. Ett annat sätt att manipulera redovisningen är att redovisa högre avsättningar då företagen förväntar sig ett sämre resultat, för att på så vis inte ha lika stora avsättningar åren därpå och därmed kunna redovisa ett bättre resultat nästkommande år. Studien kommer att undersöka ifall stora nedskrivningar och avsättningar förekommer i samband med att en ny VD träder fram. Syfte: Syftet med denna studie är att undersöka och analysera om Big Bath Accounting förekommer i företag registrerade på Nasdaq OMX Stockholm och Nasdaq OMX Helsinki. Studien fokuserar på att undersöka huruvida det råder ett samband mellan stora engångskostnader och VD-byten samt om det förekommer några skillnader mellan Sverige och Finland. Avgränsningar: Studien avgränsar sig till samtliga företag som är registrerade på Stockholmsbörsen och Helsinkibörsen Large Cap mellan åren 2005-2011. Metod: Undersökningsmetoden som har tillämpats för denna studie har en kvantitativ ansats och har använts sig av sekundär data i form av årsredovisningar. Studiens datainsamling sker med hjälp av tillgänglig information som redan finns elektroniskt på företagens hemsidor. Dessutom har en deduktiv undersökningsansats tillämpats, då studien utgår ifrån teorier som har formats till hypoteser som skall jämföras med data för att kunna komma fram till en slutsats. Ett t-test kommer att användas i studien för att testa hypoteserna som påstår att det finns ett samband mellan VD-byten och nedskrivningar av goodwill och avsättningar till långfristiga skulder. Resultat och slutsatser: T-testet visade att det inte råder ett statistiskt samband mellan VD-byten och nedskrivning av goodwill och avsättningar till långfristiga skulder. Då man bortser från t-testet och tittar närmare på vissa företag kan man se att det förekommer större engångskostnader vid VD-byten än år utan VD-byten, eftersom detta endast förekommer i vissa fall kan man inte dra en generell slutsats i frågan. Förslag till fortsatt forskning: Eftersom den insamlade datan visade på vissa likheter mellan Sverige och Finland, båda länderna hade flest VD-byten år 2011 och högst KEK år 2007, skulle det vara intressant att studera om detta är en slump eller om det föreligger något intressant samband. Vidare kan man studera huruvida dessa likheter förekommer mellan alla nordiska länder. Stora nedskrivningar och avsättningar inträffade inte endast vid ett VD-byte utan i vissa fall förekom de även 1-2 år efter att ett VD-byte skett. Vi anser därför att det skulle vara intressant att föra vidare förslaget om att inte endast kolla på året då ett VD-byte skett utan under en längre period.

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