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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.
81

`n Operasionele bestuursmodel vir die nie-geprogrammeerde opknapping van goedere treintrokke

16 August 2012 (has links)
M.Comm. / Operational management is to plan and control the transformation process that converts the requirements of customers into a product or a service. The non programmed refurbishing of railway wagons at Transwerk (Germiston) is a very difficult task for the operational manager. The number of wagons and what to repair on each wagon, only become known when the wagon arrives at Transwerk. The planning and scheduling of resources like labour, material, facilities, equipment and cash flow are therefor not so easy. To overcome the difficulties of the planning and scheduling of resources, and to refurbish the wagons according to the customer's requirements and satisfaction, it is necessary to have an operational management model or system. This system comprises of functions like aggregate planning, production scheduling, planning for fixed and variable capacities, inventory planning, design of the operational process itself as well as the control of the whole system. All of this must be set in a framework of the company's overall strategy as well as the financial and operational strategies. The first part of this study deals with the heories of operational management. It is important that the operational manager is familiar with the types of decisions to be made and what concepts are available to optimise his decisions. He also needs to know which product positioning strategy and which process positioning strategy to take. In the case of Transwerk a make-to-order product positioning strategy will be used to refurbish the wagons, and a make-to-stock strategy to manufacture the components that are needed to repair the wagons. A job-shop process positioning strategy will be used, because no fixed process flow can be followed to repair the different wagons. In the second part of this study an empirical research was done. The frequency and number of the different types of wagons that were sent to Transwerk, as well as the occurrence of the repair types on the wagons, were researched. Four years (1992 to 1995 book year) of information were used. The number of wagons and when the wagons might come in for repairs in 1996, as well as what types of repairs to do, are forecasted by using quantitative techniques as time series decomposition and weighted moving averages. The forecast or aggregate plan is the starting point of any operational model. Finally the operational model is designed. The model starts with the business- and operational strategies followed by the production plan. The production plan, derived from the forecast, shows the wagons that are expected to be built for the next five years. Transwerk should check the major available resources to assure that the production can be met. After the production plan is authorised by the executive manager the operational manager can do the master schedule. This schedule shows by model level which wagon types are expected to be repaired per day per month. This information also comes from the forecast that was done. Out of the master schedule, the material- and capacity plans can be drawn up. Production can start once the operational manager finds the planning to be correct. It is important that every step in the model is controlled and that the plans are changed if necessary. A well defined operational management model will help Transwerk on the way to be a world class company.
82

Hur ser framtiden ut för bilindustrin och hur väl är Volvo Cars redo för framtiden? : En djupdykning i bilindustrins framtida utmaningar utifrån ett forsknings- och utvecklingsperspektiv

Matsson, Cecilia, Johansson, Matilda January 2016 (has links)
Background: The global car industry is going through a process of change where the traditional car companies are being challenged. It is essential for those companies to keep up with the changing market conditions and invest in research and development, if they want to remain competitive in the future market. Volvo Cars is a prominent car manufacturer in Sweden, but is small globally. It was, therefore, adjudged as an interesting company to research with respect to how they address the aforementioned challenges.  Purpose: With an understanding and focus on the car industry’s new challenges, the purpose of this study is to investigate and illustrate Volvo Cars’ future prospective on the global car market. Method: The study has combined quantitative and qualitative approaches, viewed from an inductive perspective. Qualitative interviews were performed to obtain a deeper understanding of the car industry’s challenges, and data from secondary sources were collected in order to quantify Volvo Cars’ performance relative to other car companies. Result: The study determined the main challenges for the future of the personal vehicle sector to be: automation, environment, changing customer demand and digitalization. In addition to the innovation-based challenges mentioned above, the expanding Chinese market has been identified as a challenge for car companies to capitalise on. The expansion of the Chinese market is due to the rapidly increasing middle class, combined with a low car density. The idea that China (and the rest of Asia) will become an important future market is supported by the opinions of many experts and interview respondents who believe that car density in the western world will decline which means strengthen the importance of China as a future market. Volvo Cars face the same challenges as other car manufacturers. However, given their small global significance, Volvo Cars will need to focus and appropriately allocate their resources on only one or two challenges. In terms of investing in research and development, Volvo Cars is at the forefront, with a significant portion of their revenue being dedicated to the area. Conclusion: Given Volvo Cars’ small global significance, they will not have the ability to focus on all challenges. Instead, they must focus their research and development on a select few areas to be able to compete in the future automotive market. This study has identified three major challenges for Volvo Cars: to successfully grow in China (as well as in the rest of Asia), to increase total sales and market share, and to advance within automation and electrical operation. Given that Volvo Cars continue increasing their sales, especially in China, while simultaneously investing in research and development aimed at automation and electric drive, the researchers believe that the future of Volvo Cars is very promising. / Bakgrund: Bilindustrin går igenom en förändringsprocess och de traditionella biltillverkarna står inför stora utmaningar. I och med detta är det viktigt för bilföretagen att hänga med i processen och investera i forskning och utveckling, om de vill konkurrera om framtida marknadsandelar. Volvo Cars är en ledande aktör på den svenska marknaden samtidigt som de är små på den globala marknaden, vilket väcker ett intresse hos forskarna att studera företaget med avseende på hur det kommer att hantera dessa framtida utmaningar. Syfte: Syftet är att med utgångspunkt från bilindustrins nya utmaningar undersöka och belysa Volvo Cars framtidsutsikter på den globala bilmarknaden. Metod: Studien bygger på en kombination av kvalitativ och kvantitativ forskningsstrategi med ett induktivt angreppsätt. Kvalitativa intervjuer har genomförts för få en djupare förståelse för bilindustrins utmaningar och sekundärdata har samlats in för att på ett kvantitativt sätt visa hur Volvo Cars förhåller sig gentemot andra bilföretag på den globala marknaden. Resultat: Studien har kommit fram till att de största utmaningarna för bilindustrins framtid handlar om: automatisering, miljö, ägande och digitalisering. Utöver de innovativa utmaningarna har Kina identifierats som en utmaning för bilföretagen. Eftersom Kina har en snabbt ökande medelklass i kombination med att landet har en låg biltäthet förväntas bilförsäljningen i regionen öka. Då många experter och intervjurespondenter anser att försäljningen av bilar kommer minska i västvärlden kommer därför en ökad försäljning i Kina och övriga Asien bli avgörande för många bilföretag. Volvo Cars har samma utmaningar att bemästra som de andra aktörerna på marknaden men eftersom de är en mindre aktör måste de fokusera på en eller två utmaningar och hoppas på att de är rätt. Studien har även visat att Volvo Cars satsar en stor procent av deras omsättning på just forskning och utveckling jämfört med andra (undersökta) aktörer på marknaden. Slutsats: Då Volvo Cars är en liten aktör på den globala marknaden kommer de inte ha möjlighet att satsa på samtliga utmaningar utan måste fokusera sin forskning och utveckling på ett fåtal faktorer för att kunna konkurrera på framtidens bilmarknad. Studien har specificerat tre utmaningar för Volvo Cars att uppnå för goda framtidsutsikter: lyckas växa på den kinesiska (och övriga asiatiska) marknaden och därmed öka den totala försäljningen och marknadsandelarna samt bemästra de innovativa utmaningarna inom automatisering och eldrift. Med det sagt kan forskarna dra slutsatsen att Volvo Cars framtid ser lovande ut förutsatt att de fortsätter öka sin försäljning, framförallt i Kina, samtidigt som de helhjärtat satsar på forskning och utveckling inom områdena automatisering och el-drift.
83

Nouveaux dispositifs pour l'application contrôlée d'impulsions électriques nanosecondes et pour la détection de leurs effets sur les cellules : Nouveaux résultats et hypothèses sur les paramètres contrôlant l'électroperméabilisation des cellules biologiques / New devices for the controlled application of nanosecond electrical pulses and the detection of their effects on cells : New findings and hypotheses on the parameters controlling the electropermeabilization of biological cells

Silve, Aude 23 November 2011 (has links)
La manipulation des membranes des cellules en suspension ou dans des tissus au moyen d’impulsions électriques constitue un sujet de recherche majeur au cœur du bio-électromagnétisme. A ce jour les impulsions de quelques microsecondes voire millisecondes ont été principalement étudiées. Elles n’affectent que la membrane plasmique des cellules. Les impulsions nanosecondes de fort niveau de champ (de l’ordre de quelques MV/m) ouvrent la voie vers la manipulation des organelles intra-cellulaires. En outre, elles constituent un nouvel outil pour l’étude des mécanismes de la perméabilisation. Les travaux de cette thèse ont été principalement consacrés aux effets des impulsions de 10 ns sur la membrane plasmique. Des protocoles expérimentaux permettant d’appliquer de façon reproductible et contrôlée les impulsions sur des objets vivants ont été définis. Des moyens de mesure (D-dot et B-dot) adaptés aux hautes tensions et hautes fréquences ont été développés et mis en œuvre, permettant un contrôle en temps réel des impulsions délivrées.Différentes approches ont permis de mettre en évidence la perméabilisation des cellules par des impulsions de 10 ns. Ces techniques regroupent notamment le suivi de bio-impédance dans les tissus et l’internalisation de molécules cytotoxiques non perméantes dans des cellules en suspension et in vivo sur des tumeurs. Les expériences conduites ont permis de mettre en évidence la plus grande efficacité des basses fréquences de répétition dans la perméabilisation d’un tissu végétal (la pomme de terre). De plus l’influence de la conductivité du milieu extracellulaire sur le niveau de perméabilisation a été investiguée. Ces expériences ont permis de mettre en évidence l’importance de la dynamique d’établissement et de relaxation de la différence de potentiel transmembranaire dans l’efficacité de la perméabilisation.Enfin un microscope CARS (Coherent Anti-stokes Raman Scattering) plein-champ a été développé. Sa conception a été pensée en vue de l’étude des effets des impulsions ultra-courtes sur le vivant à l’échelle moléculaire. A ce jour il permet d’obtenir des images de cellules en CARS en 3 ns. / New devices for the controlled application of nanosecond electrical pulses and the detection of their effects on cells. New findings and hypotheses on the parameters controlling the electropermeabilization of biological cells.Abstract:Manipulation of the membranes of cells in suspension or in tissues with electrical pulses is a major research topic in bio-electromagnetism. Until recently the effects of pulses of a few microseconds or milliseconds have mainly been studied. Such pulses only affect the cell plasma membrane. Pulses of a few nanoseconds with high field strength (of the order of a few MV /m) might lead to intracellular organelles manipulation. In addition, they represent a new tool to study the mechanisms of permeabilization.This thesis was mainly devoted to the effects of pulses of 10 ns on the plasma membrane. Experimental protocols to apply controlled and reproducible pulses on living objects have been defined. Measurement means (D-dot and B-dot) adapted to high voltages and high frequencies have been developed and implemented thus allowing for accurate and real-time monitoring of the pulses applied on the biological samples.Different approaches have been used to highlight the permeabilization of biological cells by pulses of 10 ns. The techniques used include the monitoring of bio-impedance in tissues and the internalization of non-permeant cytotoxic molecules in cells in suspension and in vivo in tumors. The conducted experiments allowed to demonstrate the high efficiency of low repetition rates in permeabilizing potato tissue. The influence of the conductivity of the extracellular medium on the efficiency of the permeabilization was also investigated. These experiments highlighted the important role played by the dynamic of the establishment and relaxation of the transmembrane potential difference.Finally a wide-field CARS microscope (Coherent Anti-Stokes Raman Scattering) was developed. It has been designed to study the effects of ultra-short pulses on biological cells at the molecular level. It already enables to obtain images of cells in 3 ns.
84

Espectroscopia de ions Eu+3 em cristais de baixa simetria / Espectroscopy of Eu+3 ions in low simmetry cristals.

Oliveira, Antonio Cesar de 21 February 1991 (has links)
Neste trabalho estudamos o íon Eu3+ no aluminato EuAlO3 e no garnet Ca3Ga2Ge3O12:Eu+3 através de espectroscopia óptica. Técnicas convencionais de absorção e fluorescência foram utilziadas, e elas nos permitiram um levantamento sistemático dos níveis eletrônicos 7FJ (J= 0,1,2,3,4) e 5DJ (J= 0,1,2) do Eu+3. A análise dos espectros de absorção feitos com luz polarizada confirma a ocupação dos íons Eu+3 em sítios de simetria C no EuAlO3. Com isso também confirmamos as regras de seleção esperadas. Efetuamos medidas da variação da largura de linha com a temperatura, da transição 7F1 &#8594 5D0 em EuAlO3. Isso nos permitiu determinar a estatística de íons excitados termicamente ao sub-nível 7F1, cuja energia é próxima a kT para temperatura ambiente. Os espectros de fluorescência resolvida no tempo nos forneceram o comportamento do decaimento radiativo em função da temperatura para as transições 5D0 &#8594 7FJ do Eu3+ tanto no sistema EuAlO3 quanto no garnet Ca3Ga2Ge3O12:Eu+3. Além das técnicas convencionais citadas acima, utilizamos também uma técnica espectroscópica não linear denominada Coherent antiStokes Raman Spectroscopy. Essa é uma técnica muito útil na determinação de níveis vibracionais ou eletrônicos na região de infravermelho. O processo de alinhamento e medidas preliminares foram feitos com o benzeno e a calcita (CaCO3). Na seqüência processamos a detecção e o estudo de um dos níveis 7F2 do Eu+3 no garnet. / In this work we studied the íon Eu3+ in aluminate EuAlO3 and in the garnet Ca3Ga2Ge3O12:Eu+3 through the optical spectroscopy. Conventional techniques of absorption and fluorescence were used and enabled us to study systematically the levels 7FJ (J= 0,1,2,3,4) and 5DJ (J= 0,1,2) of the Eu+3. The analysis of the absorption spectra done with polarized light confirmed the occupation of ions Eu+3 on sites of C symmetry in EuAlO3. Measurements of the line width variation to the transition 7F3 &#8594 5D0 in EuAlO3 allowed us to verify the thermal nature of the levels 7FJ. The time resolved fluorescence spectra also provided us with the behavior of the radioactive decay as a function of temperature to the transitions 5D0 &#8594 7FJ of the Eu3+ in EuAlO3 as well as in the garnet Ca3Ga2Ge3O12:Eu+3. Coherent antoStokes Raman Spectroscopy technique non-linear, was also used as a complementary technique to the conventional ones cited above. This technique is very usefull to determine levels in the infra-red range. The aligment process and some preliminary measurements were done with benzene and calcite (CaCO3). The results obtained by detection of one of the Eu+3 levels 7F2 were studied.
85

The influence of finite bandwidth actuators on rail vehicle active suspensions

Buzan, Forrest T January 1982 (has links)
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Includes bibliographical references. / by Forrest T. Buzan. / M.S.
86

Optimization of front Wheel Arch Liner

Torstensson, Martin, Pettersen, Hans January 2006 (has links)
<p>About ten years ago Volvo Cars could see that car manufactures began to introduce rear wheel arch liners made of non-woven fabrics or some kind of laminate which are mostly common today. Volvo Cars have also seen that competitors now are beginning to develop the front wheel arch liners more and more and expect a development equal to the one for the rear wheel arch liners. This is why we are set to optimize the front wheel arch liner.</p><p>For development of mechanical products such as car parts, a discursive method is most suitable to follow. For example systematical concept development which we have used in our work.</p><p>From a technical point of view, our results shows that the penta laminate used for the wheel arch liner on Mercedes Benz S-class is by far the best material. Unfortunately it is rather expensive which of course affects its result in a negative way when cost is taken in to consideration. When including cost, the solid plastic is actually rather economical.</p><p>After assessment of the result in total we are however convinced that Volvo Cars should concentrate on further research of penta laminate and open negotiations with different suppliers regarding a material of this kind.</p><p>Regarding the geometry, the tests and studies that Volvo Cars have performed earlier on splash shields clearly shows the usage of the part and further research done by our selves does not point at any problems with a splash shield integrated in the wheel arch liner.</p> / <p>För ungefär tio år sedan kunde Volvo Cars se att biltillverkare började introducera bakre hjulhus tillverkade av ”non-woven” fibrer eller någon form av laminat vilket idag är högst vanligt. Volvo Cars har också sett att konkurrenter nu börjar utveckla främre hjulhus mer och mer och räknar med en utveckling liknande den för bakre hjulhus. Detta är anledningen till att vi har fått uppgiften att optimera det främre hjulhuset.</p><p>För utveckling av mekaniska produkter så som bildelar, är en diskursiv metod mest lämpad att följa. Till exempel systematisk konceptutveckling som vi har valt att använda i vårt arbete.</p><p>Sett ur ett tekniskt perspektiv, visar våra resultat att pentalaminatet som används för hjulhusen på Mercedes Benz S-klass, är det överlägset bästa materialet. Tyvärr ar det ganska dyrt vilket naturligtvis påverkar dess resultat negativt när hänsyn tas till kostnader. När vi även ser till kostnaderna, är faktiskt den rena plasten mycket ekonomisk. Efter bedömning av det totala resultatet, är vi helt övertygade om att Volvo Cars borde koncentrera sig på fortsatta undersökningar av pentalaminat och inleda förhandlingar med olika underleverantörer angående material av denna typ.</p><p>Angående geometrin, visar Volvo Cars’ sedan tidigare genomförda tester och studier att en splash shield fyller en viktig funktion och vidare undersökningar genomförda av oss själva pekar inte på några problem med en i hjulhuset integrerad splash shield.</p>
87

Optimization of front Wheel Arch Liner

Torstensson, Martin, Pettersen, Hans January 2006 (has links)
About ten years ago Volvo Cars could see that car manufactures began to introduce rear wheel arch liners made of non-woven fabrics or some kind of laminate which are mostly common today. Volvo Cars have also seen that competitors now are beginning to develop the front wheel arch liners more and more and expect a development equal to the one for the rear wheel arch liners. This is why we are set to optimize the front wheel arch liner. For development of mechanical products such as car parts, a discursive method is most suitable to follow. For example systematical concept development which we have used in our work. From a technical point of view, our results shows that the penta laminate used for the wheel arch liner on Mercedes Benz S-class is by far the best material. Unfortunately it is rather expensive which of course affects its result in a negative way when cost is taken in to consideration. When including cost, the solid plastic is actually rather economical. After assessment of the result in total we are however convinced that Volvo Cars should concentrate on further research of penta laminate and open negotiations with different suppliers regarding a material of this kind. Regarding the geometry, the tests and studies that Volvo Cars have performed earlier on splash shields clearly shows the usage of the part and further research done by our selves does not point at any problems with a splash shield integrated in the wheel arch liner. / För ungefär tio år sedan kunde Volvo Cars se att biltillverkare började introducera bakre hjulhus tillverkade av ”non-woven” fibrer eller någon form av laminat vilket idag är högst vanligt. Volvo Cars har också sett att konkurrenter nu börjar utveckla främre hjulhus mer och mer och räknar med en utveckling liknande den för bakre hjulhus. Detta är anledningen till att vi har fått uppgiften att optimera det främre hjulhuset. För utveckling av mekaniska produkter så som bildelar, är en diskursiv metod mest lämpad att följa. Till exempel systematisk konceptutveckling som vi har valt att använda i vårt arbete. Sett ur ett tekniskt perspektiv, visar våra resultat att pentalaminatet som används för hjulhusen på Mercedes Benz S-klass, är det överlägset bästa materialet. Tyvärr ar det ganska dyrt vilket naturligtvis påverkar dess resultat negativt när hänsyn tas till kostnader. När vi även ser till kostnaderna, är faktiskt den rena plasten mycket ekonomisk. Efter bedömning av det totala resultatet, är vi helt övertygade om att Volvo Cars borde koncentrera sig på fortsatta undersökningar av pentalaminat och inleda förhandlingar med olika underleverantörer angående material av denna typ. Angående geometrin, visar Volvo Cars’ sedan tidigare genomförda tester och studier att en splash shield fyller en viktig funktion och vidare undersökningar genomförda av oss själva pekar inte på några problem med en i hjulhuset integrerad splash shield.
88

The U.S. passenger car industry in the 1980's

Yang, Ling 15 February 2008 (has links)
American automobile manufacturers experienced a bitter-sweet time during the 1980s. On one hand, they gained support from the government to prevent mass imports of small cars from Japan; while on the other hand, they still lost market share to their Japanese counterparts and ever since then, they have been facing fierce competition from the Japanese auto-makers. To better understand today s competition in the automobile market, it is crucial to study the industry in the 1980s when the scope of the market began to change. This paper focuses mainly on studying the compact car market in the 1980s, which was the primary competition field then. It first briefly introduces the rise of Japanese automobile industry, and the economic background of the decade. Then it examines the U.S. compact car segment in detail, and finally constructs a model to explain consumer decisions on purchasing compact cars. In the end, it gives suggestion to the Big Three companies according to the findings presented in this paper.
89

Simulation and optimization of a fuel cell hybrid vehicle

Brown, Darren. January 2008 (has links)
Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisors: Ajay K. Prasad and Suresh G. Advani, Dept. of Mechanical Engineering. Includes bibliographical references.
90

Espectroscopia de ions Eu+3 em cristais de baixa simetria / Espectroscopy of Eu+3 ions in low simmetry cristals.

Antonio Cesar de Oliveira 21 February 1991 (has links)
Neste trabalho estudamos o íon Eu3+ no aluminato EuAlO3 e no garnet Ca3Ga2Ge3O12:Eu+3 através de espectroscopia óptica. Técnicas convencionais de absorção e fluorescência foram utilziadas, e elas nos permitiram um levantamento sistemático dos níveis eletrônicos 7FJ (J= 0,1,2,3,4) e 5DJ (J= 0,1,2) do Eu+3. A análise dos espectros de absorção feitos com luz polarizada confirma a ocupação dos íons Eu+3 em sítios de simetria C no EuAlO3. Com isso também confirmamos as regras de seleção esperadas. Efetuamos medidas da variação da largura de linha com a temperatura, da transição 7F1 &#8594 5D0 em EuAlO3. Isso nos permitiu determinar a estatística de íons excitados termicamente ao sub-nível 7F1, cuja energia é próxima a kT para temperatura ambiente. Os espectros de fluorescência resolvida no tempo nos forneceram o comportamento do decaimento radiativo em função da temperatura para as transições 5D0 &#8594 7FJ do Eu3+ tanto no sistema EuAlO3 quanto no garnet Ca3Ga2Ge3O12:Eu+3. Além das técnicas convencionais citadas acima, utilizamos também uma técnica espectroscópica não linear denominada Coherent antiStokes Raman Spectroscopy. Essa é uma técnica muito útil na determinação de níveis vibracionais ou eletrônicos na região de infravermelho. O processo de alinhamento e medidas preliminares foram feitos com o benzeno e a calcita (CaCO3). Na seqüência processamos a detecção e o estudo de um dos níveis 7F2 do Eu+3 no garnet. / In this work we studied the íon Eu3+ in aluminate EuAlO3 and in the garnet Ca3Ga2Ge3O12:Eu+3 through the optical spectroscopy. Conventional techniques of absorption and fluorescence were used and enabled us to study systematically the levels 7FJ (J= 0,1,2,3,4) and 5DJ (J= 0,1,2) of the Eu+3. The analysis of the absorption spectra done with polarized light confirmed the occupation of ions Eu+3 on sites of C symmetry in EuAlO3. Measurements of the line width variation to the transition 7F3 &#8594 5D0 in EuAlO3 allowed us to verify the thermal nature of the levels 7FJ. The time resolved fluorescence spectra also provided us with the behavior of the radioactive decay as a function of temperature to the transitions 5D0 &#8594 7FJ of the Eu3+ in EuAlO3 as well as in the garnet Ca3Ga2Ge3O12:Eu+3. Coherent antoStokes Raman Spectroscopy technique non-linear, was also used as a complementary technique to the conventional ones cited above. This technique is very usefull to determine levels in the infra-red range. The aligment process and some preliminary measurements were done with benzene and calcite (CaCO3). The results obtained by detection of one of the Eu+3 levels 7F2 were studied.

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