Thesis (M.S.)--University of Michigan, 1968.

Originally presented as the author's dissertation: Berlin, Freie Universiẗat, Diss., 2005. / Includes bibliographical references (p. 314-345).

Originally presented as the author's dissertation: Berlin, Freie Univ., Diss., 2005. / Includes bibliographical references (p. 314-345).

Le travail de thèse effectué a pour objectif le développement d’un concept innovant de module photovoltaïque à faible concentration ultra-intégré, nommé HIRL pour Highly Integrated ReceiverLess module.Un premier Chapitre est consacré à la présentation du photovoltaïque à concentration (CPV) afin de positionner ce développement d’un concept original innovant. Le module développé est basé sur des concentrateurs réflectifs cylindro-paraboliques et il intègre des cellules multi-jonctions haut rendement. L’ambition est de travailler sur la simplification de la mise en module des cellules, en proposant d’une part, une architecture ultra-intégrée. L’optique de concentration en aluminium est multifonction puisqu’elle combine les fonctions de concentrateur, de support des cellules et de dissipateur thermique. D’autre part nous souhaitons appliquer pour ce concept des procédés de fabrication simples et éprouvés issus de l’industrie du photovoltaïque, tels que l’encapsulation par lamination. Enfin le module doit offrir une acceptance angulaire suffisante (> ±1°) pour utiliser un tracker un axe bas coût.Dans un second Chapitre, après avoir défini l’architecture de module envisagée, la modélisation thermique du système est présentée. Une étude a permis de définir les dimensions optimisées du concentrateur vis-à-vis de son rôle de dissipateur thermique. Ensuite, nous avons pu explorer les procédés de mise en forme des optiques mais également les méthodes d’interconnexion des cellules. Nous avons également mis en œuvre le procédé de lamination pour l’encapsulation des cellules multi-jonctions et démontrer la faisabilité de ce procédé pour le concept HIRL. Les procédés de fabrication identifiés ont été mis en œuvre pour la fabrication d’un prototype atteignant une efficacité électrique de 28%. La mesure de l’acceptance angulaire, de ±0.55°, a cependant montré les limites de ce premier design.Le troisième Chapitre est donc consacré à l’optimisation de l’architecture et des procédés au regard des résultats du Chapitre 2. Nous avons pu montrer comment modifier le design pour augmenter l’acceptance angulaire du module en conservant une bonne dissipation thermique. Enfin, de nouveaux procédés ont été mis en œuvre pour la réalisation d’un nouveau prototype fabriqué selon ce nouveau design et intégrant des cellules multi-jonctions optimisées pour la faible concentration. Ce nouveau prototype V3 présente un rendement de 30,5% et un angle d’acceptance de +/-1.4°.Dans le quatrième Chapitre, nous nous sommes attachés à caractériser les performances optiques des concentrateurs réalisés. Un banc de caractérisation optique a spécialement été développé pour ce type de module. Il a permis la comparaison des rendements optiques des différents concentrateurs, associés à leur procédé de mise en forme, ainsi que la comparaison de leur acceptance angulaire. Enfin, nous avons pu constater les effets de l’échauffement du concentrateur - du fait de son rôle de dissipateur thermique – sur les performances optiques.Enfin, dans un dernier Chapitre, une analyse de la chaine de pertes de la cellule au module est présentée. La caractérisation optiques du revêtement réflectif mais également des matériaux d’encapsulation des cellules ont été réalisés. En combinant ces résultats avec la mesure de réponse spectrale des cellules, nous avons pu calculer les performances optiques théoriques maximales atteignables par le module avec ces matériaux. Les moyens de caractérisations en simulateur solaire ont été adaptés afin de permettre la mesure de rendement de la cellule au module. Ces caractérisations ont permis de dresser un bilan de la distribution des pertes de puissance de la cellule au module. Ainsi, nous avons pu identifier les voies d’optimisation de ce module HIRL qui pourrait atteindre une efficacité électrique de 33%. / The aim of the work presented in this thesis is to develop an innovative low-concentration photovoltaic (PV) module with a high level of integration, a “Highly Integrated ReceiverLess” module named “HIRL”.The concentrated photovoltaic (CPV) technology is presented in the first Chapter with the aim to position the development of this novel concept. The developed module is based on a parabolic-trough concentrator and on the integration of high-efficiency multi-junction solar cells. The idea is to simplify the cell integration in the module via an optimized architecture. The innovation is the multi-functionality of the concentrator mirror acting as primary optical element (POE), which, in addition to having an optical function, becomes both the mechanical support of the cell arrays and the heat sink responsible of the cell cooling. Moreover, this concept relies on well-known, high-throughput, reliable and cost-effective flat-plate PV manufacturing techniques, such as lamination, for the cell array assembly into the rear of the POE. Finally the module is developed to reach an angular acceptance compatible with low cost one axis trackers (> ±1°).The thermal modeling of the module is presented in the second Chapter. This model is used to define the mirror dimensions that guarantee an optimized thermal cooling within the mirror element. Then, we have studied and tested different fabrication processes for the optics forming and cells interconnection. Moreover the feasibility of the lamination process for multi-junction cells encapsulation has been demonstrated for the HIRL concept. The application of the identified processes for prototype fabrication has allowed to fabricate a module reaching an electrical efficiency of 28%. However, the measured acceptance angle is of ±0.55°. It has shown that this design cannot reach the expected acceptance angle value.Based on Chapter 2 results, the architecture and fabrication processes are optimized in the third Chapter. The design has been modified with the aim to increase the angular acceptance while maintaining a sufficient thermal cooling. Moreover, new fabrication processes have been applied on a new prototype which integrates multi-junction cells optimized for low concentration. This new prototype reached 30.5% electrical efficiency and a ±1.4° acceptance angle compatible with low cost one axis tracker.In the Chapter 4, an optical characterization bench has been developed to compare the optical performances of the different optical concentrators fabricated. It allowed to compare the optical efficiency and the angular acceptance of these optical elements, related to different mirror forming techniques. Moreover, the capability of controlling the mirror temperature is also implemented to study thermal effects on the optical performances. It is shown that the mirror heating decreases significantly the acceptance angle of the module.Finally, in the fifth Chapter, an advanced characterization of the power loss mechanisms is presented, from the cell to the module. We calculated the maximum theoretical reachable cell to module ratio for the considered cell and materials based on experimental spectral response and mirror reflectivity measurements. Furthermore a solar simulator has been adapted for cell and module IV measurements to quantify total cell-to-module losses. These characterizations allowed to define the different power loss sources from the cell to the module. The optimization of mirror reflectivity and concentrator forming could increase the electrical efficiency to 33%.

The difficulties of finding original material in general practice on which to write a Thesis made the author review his Service experience and choose the aforementioned subject. Whilst serving with the 11th Light Field Ambulance the author had the dubious privilege of working in the huts of Belsen Camp from the day of liberation onwards until the last hut was burned down by the British after complete evacuation of the camp. Few people who worked there can at any time have seen a greater wealth of clinical material. The death rate whilst evacuation was proceeding between April 20th, 1945 and May 17th, 1945, numbered some thirteen thousand in Camp 1 alone. In perusing the small amount of literature existing on the subject it is surprising that no real intensive clinical investigations seem to have been carried out at the Camp. The reasons for this are not far to seek. The magnitude of the problem which existed and smallness of resources of the liberating forces in men and material made the problem largely an administrative one of extreme urgency. Everyone in the area was employed in providing the daily wants of an average community to the internees. Food, water and clothing had to be provided. Some semblance of hygiene and order had to be brought to the Camp and an attempt made to evacuate the seriously ill estimated at some twenty eight thousand in Camp I and three thousand in Camp II. Along with another officer the author was responsible for the collection and evacuation of the sick from Camp I to Casualty Clearing Stations and General Hospitals in the neighbourhood. The appalling conditions of filth and squalor in the camp and a death rate of five hundred a day at the outset made speed in evacuation the prime consideration. Under these circumstances and because of language difficulties it was impossible to carry out a detailed examination of all patients, nor was it possible to keep clinical records. Many cases were examined in detail however end several visits were paid by the author to general hospitals where conditions were considerably more suitable for examination. Naturally no special investigations could be carried out by the author and cases were examined solely by clinical means.

The potentiometric method is one of the most exact techniques of electrochemistry. Its use is widespread in both routine measurements, such as pH determination, and in applications which demand the highest accuracy. Perhaps its severest limitation is the error due to liquid junction potentials. Although this has been the subject of much study, and although various means of combating it have been proposed, it has defied all attempts at a satisfactory solution. Indeed, so serious is the position that it has become the accepted practice in the more accurate fields to abandon altogether the use of potentiometric techniques in favour of others, usually less convenient and otherwise less accurate, when the presence of liquid junctions cannot be avoided. Intro. p. 1.

MSCPNT / Department of Nutrition / Introduction: Iodine is an essential nutrient required by humans for the synthesis of thyroid hormones, which are vital for normal growth and development. Objective: The primary aim of the study was to describe the iodine status of lactating mothers and infants aged from 0 to 6 months in the Vhembe and Mopani Districts. Methods: A cross-sectional study conducted on 246 infant-mother pair, from the Mopani and the Vhembe Districts. Data was gathered using a questionnaire. Breastmilk, mother urine, infant urine, household salt and drinking water were collected to be analysed for iodine content. Results: The median of breastmilk iodine concentration level amongst lactating mothers in the Vhembe District was 101.4 µg/l (IQR 62.9 – 175.1 µg/l) and 154.4 µg/l (IQR 92.6 – 211.8 µg/L) in Mopani. The median UIC of mothers in Vhembe was 98.5 (IQR 57.66 – 153.93), whereas in the Mopani District the median UIC of mothers was 126.08 µg/l (IQR 69.89 – 206.71 µg/L). The median UIC of infants in Vhembe was 220 (IQR 106.67 – 418.43 µg/l) and in the Mopani District was 321.94 µg/l (IQR 167.96 – 482.66 µg/l). Conclusion: The BMIC in the study signifies iodine sufficiency in both the Vhembe and the Mopani Districts. The results of this study suggest that the BMIC be included in studies assessing iodine status in lactating mothers since the UIC only reflects iodine that was consumed recently. The UIC may under estimate the maternal iodine status if it is not complemented by the BMIC data. / NRF

Le lithium est le traitement de référence du trouble bipolaire. Cependant, il peut être responsable d’intoxications dont trois profils différents sont décrits chez l’homme, caractérisés par une expression variable encore inexpliquée de la neurotoxicité. Les objectifs de cette thèse étaient d’étudier la distribution cérébrale du lithium dans trois modèles de rats Sprague-Dawley reproduisant les modes d’intoxication au lithium chez l’homme et de déterminer son implication dans la survenue des complications neurologiques au moyen de tests comportementaux et d’une analyse électroencéphalographique. Dans ce contexte, une étude des relations effet/concentrations du lithium suivant le modèle d’intoxication a été conduite. Enfin, un protocole d’imagerie ex vivo permettant d’explorer la distribution intracérébrale du lithium a été mis en place chez le rat par résonance magnétique nucléaire du lithium-7. Ainsi, nous avons montré que les trois formes d’intoxication au lithium chez le rat diffèrent en termes de pharmacocinétique sanguine et cérébrale, mais aussi en termes d’intensité et de durée des effets neurocomportementaux. Nous avons mis en évidence une accumulation cérébrale de lithium significativement plus élevée suite à un prétraitement répété par lithium et majorée après induction d’une insuffisance rénale. Le surdosage de lithium était constamment à l’origine d’une hypolocomotion chez le rat, dont la profondeur et l’étendue apparaissaient être liées à la durée de l’exposition au lithium, et d’une encéphalopathie dont la sévérité apparaissait plutôt dépendre de la quantité de lithium cérébral accumulée. Ainsi, l’accumulation cérébrale de lithium pourrait engendrer des effets neurotoxiques directs et/ou indirects par modification de l’expression de cibles cérébrales spécifiques du lithium. Enfin, nous avons démontré la faisabilité et la fiabilité de notre technique d’imagerie ex vivo pour explorer la distribution cérébrale du lithium chez le rat, ouvrant dès lors des perspectives à son utilisation future chez l’homme / Lithium is the cornerstone treatment of bipolar disorder. However, lithium may be responsible for poisoning with three various profiles reported in humans and characterized by unexplained variable resulting neurotoxicity. Our objectives were to investigate brain lithium distribution in three Sprague-Dawley rat models mimicking the human intoxication patterns and define its involvement in the occurrence of neurological disorders using behavioral tests and electroencephalographic analysis. The effect/concentration relationships were studied according to the poisoning model. Finally, an ex vivo imaging protocol was established in the rat to investigate brain lithium distribution using the nuclear magnetic resonance of lithium-7. We showed significant differences between the three lithium poisoning patterns in the rat regarding the blood and brain lithium pharmacokinetics as well as the intensity and duration of lithium-induced neurobehavioural effects. We found significantly more marked brain lithium accumulation after an overdose following repeated lithium administration, enhanced after the induction of renal failure. In the rat, lithium overdose consistently induced hypolocomotion whose intensity was related to the duration of lithium exposure and encephalopathy whose severity rather depended on the lithium amount accumulated in the brain. Brain lithium accumulation seems thus able to generate direct and/or indirect neurotoxic effects mediated by the alteration of specific brain lithium target expression. Finally, we demonstrated the feasibility and reliability of our ex vivo imaging technique to investigate brain lithium distribution in the rat, supporting a possible future use in humans

Global supply chains have become increasingly complex and a critical source of competitive advantage, which makes the understanding of how supply chains create and distribute value an essential task. Prior literature on concentration risks has primarily focused on customer concentration and has overlooked the challenges posed by the major upstream supply chain partners. In addition, CEOs with an optimal mix of technical and behavioral abilities can shape the strategic decision-making process to obtain an advantage against the nonfinancial stakeholders. The existing literature has also overlooked the significant role of the CEO in reducing the impact of supplier-base/customer-base concentrations. Utilizing objective supply chain relation data collected from Bloomberg SPLC and Compustat, we map the supplier base and the customer base for each electronic and chemical manufacturing firm publicly listed under S&P1500 for the fiscal year 2017. We then construct objective measures of supplier and customer concentrations and examine their impacts on the focal firm's financial performance measured by Tobin's Q, gross profit margin, and net profit margin. The performance metrics also include the focal firm's payable period (against the supplier-base) and receivable period (against the customer-base). We also collect information related to the CEOs appointed by the focal manufacturing firm, such as gender, age, and tenure from Execucomp, and consequently investigate their impacts on the supplier concentration and the customer concentration. Our empirical analysis shows contradictory results in the context of supplier-base/customer-base concentrations: higher supplier-base concentration is observed to harm the focal firm’s financial performance, but higher customer-base concentration leads to an increase in the focal firm’s profitability. Although CEO characteristics such as tenure and age did not have any notable impact, female CEOs are found to reduce the adversarial impact of supplier-base concentration and are assumed to exercise a voluntary power restraint against the cooperative customer-base.

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