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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.
111

The impact of distributed leadership practices on the functioning of primary schools in Johannesburg South

Singh, Sharita 10 1900 (has links)
In this study, the researcher explored the prevalence of distributed leadership practices in schools in Johannesburg South in order to illustrate how the principals in effective schools collaborated with different members of staff to ensure the school’s success. To this end, a literature study was undertaken on relevant theories and on the results of previous research on the issue. The study explored literature from local and international perspectives on distributed leadership to understand how this form of leadership impacted the functioning of primary schools in Johannesburg South. This was followed by an empirical investigation using judgemental and purposive sampling methods to select participants. A mixed methods research design was employed to elicit both quantitative and qualitative data from a single, structured questionnaire. Participants included 86 respondents from 9 primary schools. Throughout the research study, ethical considerations like keeping confidentiality of information provided and anonymity of research participants were upheld. Data analysis involved a mix of quantitative data analysis and content analysis. Based on the findings, recommendations were made to the GDE and school principals on support needed by teachers if distributed leadership is to ensure school effectiveness. The study found that distributed leadership not only motivated teachers, but compelled them to recognise their own strengths and weaknesses, and contribute to school leadership by taking on roles that interest them. Schools in Johannesburg South have created a culture in which distributed leadership tends to flourish. Distributed leadership ensures that a myriad of well-developed teachers exist at all ranks of the school, who have the capacity to fill vacant positions when a need arises to ensure the smooth functioning of schools. / Educational Management and Leadership / M. Ed. (Education Management)
112

Formal verification of a synchronous data-flow compiler : from Signal to C

Ngô, Van Chan 01 July 2014 (has links) (PDF)
Synchronous languages such as Signal, Lustre and Esterel are dedicated to designing safety-critical systems. Their compilers are large and complicated programs that may be incorrect in some contexts, which might produce silently bad compiled code when compiling source programs. The bad compiled code can invalidate the safety properties that are guaranteed on the source programs by applying formal methods. Adopting the translation validation approach, this thesis aims at formally proving the correctness of the highly optimizing and industrial Signal compiler. The correctness proof represents both source program and compiled code in a common semantic framework, then formalizes a relation between the source program and its compiled code to express that the semantics of the source program are preserved in the compiled code.
113

Evaluating reasoning heuristics for a hybrid theorem proving platform

Ackermann, Jacobus Gideon 06 1900 (has links)
Text in English with abstracts in English, Afrikaans and isiZulu / The formalisation of first-order logic and axiomatic set theory in the first half of the 20th century—along with the advent of the digital computer—paved the way for the development of automated theorem proving. In the 1950s, the automation of proof developed from proving elementary geometric problems and finding direct proofs for problems in Principia Mathematica by means of simple, human-oriented rules of inference. A major advance in the field of automated theorem proving occurred in 1965, with the formulation of the resolution inference mechanism. Today, powerful Satisfiability Modulo Theories (SMT) provers combine SAT solvers with sophisticated knowledge from various problem domains to prove increasingly complex theorems. The combinatorial explosion of the search space is viewed as one of the major challenges to progress in the field of automated theorem proving. Pioneers from the 1950s and 1960s have already identified the need for heuristics to guide the proof search effort. Despite theoretical advances in automated reasoning and technological advances in computing, the size of the search space remains problematic when increasingly complex proofs are attempted. Today, heuristics are still useful and necessary to discharge complex proof obligations. In 2000, a number of heuristics was developed to aid the resolution-based prover OTTER in finding proofs for set-theoretic problems. The applicability of these heuristics to next-generation theorem provers were evaluated in 2009. The provers Vampire and Gandalf required respectively 90% and 80% of the applicable OTTER heuristics. This dissertation investigates the applicability of the OTTER heuristics to theorem proving in the hybrid theorem proving environment Rodin—a system modelling tool suite for the Event-B formal method. We show that only 2 of the 10 applicable OTTER heuristics were useful when discharging proof obligations in Rodin. Even though we argue that the OTTER heuristics were largely ineffective when applied to Rodin proofs, heuristics were still needed when proof obligations could not be discharged automatically. Therefore, we propose a number of our own heuristics targeted at theorem proving in the Rodin tool suite. / Die formalisering van eerste-orde-logika en aksiomatiese versamelingsteorie in die eerste helfte van die 20ste eeu, tesame met die koms van die digitale rekenaar, het die weg vir die ontwikkeling van geoutomatiseerde bewysvoering gebaan. Die outomatisering van bewysvoering het in die 1950’s ontwikkel vanuit die bewys van elementêre meetkundige probleme en die opspoor van direkte bewyse vir probleme in Principia Mathematica deur middel van eenvoudige, mensgerigte inferensiereëls. Vooruitgang is in 1965 op die gebied van geoutomatiseerde bewysvoering gemaak toe die resolusie-inferensie-meganisme geformuleer is. Deesdae kombineer kragtige Satisfiability Modulo Theories (SMT) bewysvoerders SAT-oplossers met gesofistikeerde kennis vanuit verskeie probleemdomeine om steeds meer komplekse stellings te bewys. Die kombinatoriese ontploffing van die soekruimte kan beskou word as een van die grootste uitdagings vir verdere vooruitgang in die veld van geoutomatiseerde bewysvoering. Baanbrekers uit die 1950’s en 1960’s het reeds bepaal dat daar ’n behoefte is aan heuristieke om die soektog na bewyse te rig. Ten spyte van die teoretiese vooruitgang in outomatiese bewysvoering en die tegnologiese vooruitgang in die rekenaarbedryf, is die grootte van die soekruimte steeds problematies wanneer toenemend komplekse bewyse aangepak word. Teenswoordig is heuristieke steeds nuttig en noodsaaklik om komplekse bewysverpligtinge uit te voer. In 2000 is ’n aantal heuristieke ontwikkel om die resolusie-gebaseerde bewysvoerder OTTER te help om bewyse vir versamelingsteoretiese probleme te vind. Die toepaslikheid van hierdie heuristieke vir die volgende generasie bewysvoerders is in 2009 geëvalueer. Die bewysvoerders Vampire en Gandalf het onderskeidelik 90% en 80% van die toepaslike OTTER-heuristieke nodig gehad. Hierdie verhandeling ondersoek die toepaslikheid van die OTTER-heuristieke op bewysvoering in die hibriede bewysvoeringsomgewing Rodin—’n stelselmodelleringsuite vir die formele Event-B-metode. Ons toon dat slegs 2 van die 10 toepaslike OTTER-heuristieke van nut was vir die uitvoering van bewysverpligtinge in Rodin. Ons voer aan dat die OTTER-heuristieke grotendeels ondoeltreffend was toe dit op Rodin-bewyse toegepas is. Desnieteenstaande is heuristieke steeds nodig as bewysverpligtinge nie outomaties uitgevoer kon word nie. Daarom stel ons ’n aantal van ons eie heuristieke voor wat in die Rodin-suite aangewend kan word. / Ukwenziwa semthethweni kwe-first-order logic kanye ne-axiomatic set theory ngesigamu sokuqala sekhulunyaka lama-20—kanye nokufika kwekhompyutha esebenza ngobuxhakaxhaka bedijithali—kwavula indlela ebheke ekuthuthukisweni kwenqubo-kusebenza yokufakazela amathiyoremu ngekhomyutha. Ngeminyaka yawo-1950, ukuqinisekiswa kobufakazi kwasuselwa ekufakazelweni kwezinkinga zejiyomethri eziyisisekelo kanye nasekutholakaleni kobufakazi-ngqo bezinkinga eziphathelene ne-Principia Mathematica ngokuthi kusetshenziswe imithetho yokuqagula-sakucabangela elula, egxile kubantu. Impumelelo enkulu emkhakheni wokufakazela amathiyoremu ngekhompyutha yenzeka ngowe-1965, ngokwenziwa semthethweni kwe-resolution inference mechanism. Namuhla, abafakazeli abanohlonze bamathiyori abizwa nge-Satisfiability Modulo Theories (SMT) bahlanganisa ama-SAT solvers nolwazi lobungcweti oluvela kwizizinda zezinkinga ezihlukahlukene ukuze bakwazi ukufakazela amathiyoremu okungelula neze ukuwafakazela. Ukukhula ngesivinini kobunzima nobunkimbinkimbi benkinga esizindeni esithile kubonwa njengenye yezinselelo ezinkulu okudingeka ukuthi zixazululwe ukuze kube nenqubekela phambili ekufakazelweni kwamathiyoremu ngekhompyutha. Amavulandlela eminyaka yawo-1950 nawo-1960 asesihlonzile kakade isidingo sokuthi amahuristikhi (heuristics) kube yiwona ahola umzamo wokuthola ubufakazi. Nakuba ikhona impumelelo esiyenziwe kumathiyori ezokucabangela okujulile kusetshenziswa amakhompyutha kanye nempumelelo yobuchwepheshe bamakhompyutha, usayizi wesizinda usalokhu uyinkinga uma kwenziwa imizamo yokuthola ubufakazi obuyinkimbinkimbi futhi obunobunzima obukhudlwana. Namuhla imbala, amahuristikhi asewuziso futhi ayadingeka ekufezekiseni izibopho zobufakazi obuyinkimbinkimbi. Ngowezi-2000, kwathuthukiswa amahuristikhi amaningana impela ukuze kulekelelwe uhlelo-kusebenza olungumfakazeli osekelwe phezu kwesixazululo, olubizwa nge-OTTER, ekutholeni ubufakazi bama-set-theoretic problems. Ukusebenziseka kwalawa mahuristikhi kwizinhlelo-kusebenza ezingabafakazeli bamathiyoremu besimanjemanje kwahlolwa ngowezi-2009. Uhlelo-kusebenza olungumfakazeli, olubizwa nge-Vampire kanye nalolo olubizwa nge-Gandalf zadinga ama-90% kanye nama-80%, ngokulandelana kwazo, maqondana nama-OTTER heuristics afanelekile. Lolu cwaningo luphenya futhi lucubungule ukusebenziseka kwama-OTTER heuristics ekufakazelweni kwamathiyoremu esimweni esiyinhlanganisela sokufakazela amathiyoremu esibizwa nge-Rodin—okuyi-system modelling tool suite eqondene ne-Event-B formal method. Kulolu cwaningo siyabonisa ukuthi mabili kuphela kwayi-10 ama-OTTER heuristics aba wusizo ngenkathi kufezekiswa isibopho sobufakazi ku-Rodin. Nakuba sibeka umbono wokuthi esikhathini esiningi ama-OTTER heuristics awazange abe wusizo uma esetshenziswa kuma-Rodin proofs, amahuristikhi asadingeka ezimweni lapho izibopho zobufakazi zingazenzekelanga ngokwazo ngokulawulwa yizinhlelo-kusebenza zekhompyutha. Ngakho-ke, siphakamisa amahuristikhi ethu amaningana angasetshenziswa ekufakazeleni amathiyoremu ku-Rodin tool suite. / School of Computing / M. Sc. (Computer Science)
114

The role of principals in establishing and managing functional school libraries in King Cetshwayo District, KwaZulu-Natal

Dlamini, Ntombizethu Annatoria 11 1900 (has links)
It became known that South African learners’ learning outcomes rank poorly on the international stage, even if compared to less developed parts of Sub-Saharan Africa. The root cause of this problem is assumed to lie with the concern of illiteracy, which was argued, could be combated inter alia by ensuring that every public school has a stocked and functional library serviced by a fulltime proficient librarian. The aim of the study was to investigate the role of principals in establishing and managing functional school libraries in the King Cetshwayo District, KwaZulu-Natal. A qualitative investigation was done amongst school principals and their teacher librarians at five Dlangubo Circuit Schools. Data were collected by means of in-depth interviews and document analysis. The study revealed that the principals lack the training and resources to fulfil their role in establishing and maintaining functional school libraries. Recommendations were made on how principals might solve these problems in the future. / Dit het aan die lig gekom dat Suid-Afrikaanse leerders se leeruitkomste swak in die internasionale arena vertoon, selfs indien dit met minder-ontwikkelde dele van Sub-Sahara-Afrika vergelyk word. Daar word aanvaar dat die oorsaak van hier probleem vermoedelik die probleem van ongeletterdheid is, wat onder andere oorkom kan word deur te verseker dat elke openbare skool oor ’n toegeruste en funksionele biblioteek beskik wat deur ’n voltydse, bekwame bibliotekaris bestuur word. Hierdie studie ondersoek die rol van skoolhoofde in die vestiging en bestuur van funksionele skoolbiblioteke in die King Cetshwayo-distrik in KwaZulu-Natal. Daar is by vyf skole in die Dlangubu-streek ’n kwalitatiewe ondersoek met behulp van skoolhoofde en hulle onderwyser-bibliotekarisse gedoen. Data is met behulp van diepgaande onderhoude en dokumentanalise versamel. Die studie het aan die lig gebring dat die skoolhoofde ’n gebrek aan opleiding en hulpbronne het ten einde hulle rol in die vestiging en handhawing van funksionele skoolbiblioteke te vervul. Aanbevelings is gemaak oor hoe skoolhoofde in die toekoms moontlik hierdie probleme kan oplos. / Kuvele ukuthi imiphumela yokufunda abafundi baseNingizimu Afrika isezingeni eliphansi mayikeliswe neyamazwengamazwe ngisho noma isiqhathaniswa neyezingxenye ezingaka thuthuki kahle zase- Sub-Saharan Africa. Umsuka walenkinga kusolwa ukuthi udalwa ukungakhuthazwa ukufunda izincwadi nokubhala ,okuyinto okuthiwa ingaqedwa phakathi kokunye ngokuqinisekisa ukuthi zonke izikole zomphakathi zinomtapo wolwazi onezinsizakufunda nezinsizakusebenza ezanele ezisezingeni labantwana nothisha futhi owenganyelwe uthisha oqeqeshiwe ngokusebenza komtapo futhi osebenza ngokugcwele ukuqondana nomtapo wesikole. Inhloso yocwaningo ukuphenya indima yothishanhloko ekusunguleni nasekuphatheni imitapo esebenza ngendlela efanele ezikoleni zase e-King Cetshwayo District, KwaZulu-Natal. Uphenyo olunzulu lwenziwe kothishomkhulu kanye nakothisha ababakhethe ukuthi babuye babhekane nokusebenza nokuphathwa kwe -mitapo yolwazi ezikoleni zabo ezinhlanu ezise Dlangubo Circuit. Ulwazi lwaqoqwa ngama in-depth interviews kanye nokuhlaziywa kwezincwadi abasebenza ngazo ukuze umtapo wolwazi wesikole usebenze ngendlela efanele.Lolu cwaningo luveze ukuthi othishanhloko bashoda ngoqeqesho kwezokuphathwa komtapo wolwazi ezikoleni kanye nezinsizakufunda kubalwa nezinsiza kusebenza eziqondene nokusebenza kahle komtapo wolwazi ezikoleni ukuze bakwazi ukufeza indima yabo ekusunguleni nasekuphatheni gendlala imitapo yolwazi esebenza kahle ezikoleni zabo. Izincomo zenziwe ezikhombisa ukuthi othishanhloko bangazixazulula kanjani lezi zinkinga esikhathini esizayo. / Educational Management and Leadership / M. Ed. (Education Management)
115

Vérification Formelle d'un Compilateur Synchrone: de Signal vers C

Ngo, Van Chan 01 July 2014 (has links) (PDF)
Les langages synchrones tels que SIGNAL, LUSTRE et ESTEREL sont dédiés à la conception de systèmes critiques. Leurs compilateurs, qui sont de très gros programmes complexes, peuvent a priori se révéler incorrects dans certains situations, ce qui donnerait lieu alors à des résultats de compilation erronés non détectés. Ces codes fautifs peuvent invalider des propriétés de sûreté qui ont été prouvées en appliquant des méthodes formelles sur les programmes sources. En adoptant une approche de validation de la traduction, cette thèse vise à prouver formellement la correction d'un compilateur optimisé et industriel de SIGNAL. La preuve de correction représente dans un cadre sémantique commun le programme source et le code compilé, et formalise une relation entre eux pour exprimer la préservation des sémantiques du programme source dans le code compilé.
116

The leadership experiences of female secondary school principals in Sekhukhune District, Limpopo

Makgoka, Kolobe Philliah 09 1900 (has links)
Studies on women principals and leadership have been conducted in both developed and developing countries. Not much research on women leadership has been undertaken in Sekhukhune region in rural Limpopo, South Africa. The study’s interests were in the representation of women in leadership in this region. It sought to explore leadership experiences of women principals working in secondary schools in rural areas. In addition, the study sought to understand what led to their appointment, particularly in a deeply traditional and patriarchal society such as Sekhukhune region, considering both barriers as well as enhancers and how they impacted on their progress to principalship. Data were collected by means of qualitative methods; semi-structured interviews were held with six women principals from public schools only. Structured observation was also conducted during school visits, as well during interviews wherein field notes were also taken. School documents such as SGB and minute books, some policy documents, noticeboard documents, time-books, attendance registers were analysed. Existing literature on women and leadership was reviewed. Data collected was transcribed, analysed, interpreted, and findings were presented. Women principals spoke of their everyday work experiences within the context of sharing challenges and strengths in their careers. The study found out that women are their own motivators, which serves as a strong enhancer. However, women still face organisational barriers particularly in the selection procedures where gender discrimination is evident. Findings revealed that women principals continue to face myriad administrative and personal challenges when caring out their managerial duties. These include resistance from communities and staff often displayed by stereotypical attitudes and discrimination. In order to cope with some of the challenges, participants in this study innovatively employed various leadership styles such as care and nurturing, collaboration, androgyneity and spirituality. Stereotyping still exists as leadership is viewed from a male perspective. In conclusion, this study discovered that women principals displayed some values of liberal feminism in their leadership experiences; they demonstrated that they can do great things by taking part in the public sphere. / Educational Leadership and Management / M. Ed. (Educational Leadership and Management)
117

The impact of distributed leadership practices on the functioning of primary schools in Johannesburg South

Singh, Sharita 10 1900 (has links)
In this study, the researcher explored the prevalence of distributed leadership practices in schools in Johannesburg South in order to illustrate how the principals in effective schools collaborated with different members of staff to ensure the school’s success. To this end, a literature study was undertaken on relevant theories and on the results of previous research on the issue. The study explored literature from local and international perspectives on distributed leadership to understand how this form of leadership impacted the functioning of primary schools in Johannesburg South. This was followed by an empirical investigation using judgemental and purposive sampling methods to select participants. A mixed methods research design was employed to elicit both quantitative and qualitative data from a single, structured questionnaire. Participants included 86 respondents from 9 primary schools. Throughout the research study, ethical considerations like keeping confidentiality of information provided and anonymity of research participants were upheld. Data analysis involved a mix of quantitative data analysis and content analysis. Based on the findings, recommendations were made to the GDE and school principals on support needed by teachers if distributed leadership is to ensure school effectiveness. The study found that distributed leadership not only motivated teachers, but compelled them to recognise their own strengths and weaknesses, and contribute to school leadership by taking on roles that interest them. Schools in Johannesburg South have created a culture in which distributed leadership tends to flourish. Distributed leadership ensures that a myriad of well-developed teachers exist at all ranks of the school, who have the capacity to fill vacant positions when a need arises to ensure the smooth functioning of schools. / Educational Leadership and Management / M. Ed. (Education Management)
118

"Developing Device Quality Vanadium Dioxide Thin Films for Infrared Applications"

Bharathi, R January 2016 (has links) (PDF)
Vanadium oxides are being used as the thermal sensing layer because of their applications in infrared detectors. They have high temperature coefficient of resistance, favorable electrical resistance and compatibility with the MEMS technology. Of all oxides of vanadium, only vanadium dioxide (VO2)has been highly investigated as it shows first order transition (semiconducting to metal transition-SMT)at 68 oC. First order transition is understood as the sharp change in the electrical resistance. The change in resistivity in this case is of the order of 105 over a temperature change of 0.1 oC at 68 oC in a single crystal. Doping vanadium oxides with elements like Mo and W reduce the transition temperature. This is very important for room temperature electrical and optical detection. Though most of the research groups subscribe to PLD, cost-effective methods with large area deposition are major focus of this research. Hence for synthesizing VO2 in bulk and thin films, Solution Combustion Synthesis (SCS), Ultrasonic Nebulized Spray Pyrolysis of Aqueous Combustion Mixture (UNSPACM) Chemical vapour deposition (CVD)and microwave are explored. Synthesis of doped VO2 films in CVD has not been done extensively to yield optical quality thin films. Chapter I surveys the use of phase transition in oxides system for a variety of practical applications. In particular, Vanadium dioxide (VO2) is chosen as it is found to be very useful for infrared and metamaterials based applications. VO2 is known for its first-order semiconducting to metallic transition (SMT). This chapter attempts to explain the influence of processing, doping, annealing, etc on the SMT characteristics. Important aspects such as the idea of hysteresis in VO2 and similarity to martensitic transformation are discussed. The scope and objectives of the thesis are discussed here. Chapter II explains in detail the materials and methods used to synthesize VO2 both in bulk and in thin lm form and methods used to study their characteristics. Brief description on the principle and the working of the home-built experimental set up needed for this study is elicited. In chapter III, attempts were made to understand the phase stability of VO2 and the evolution of crystal structures during the phase transition. VO2 crystallizes in P21/c space group at room temperatures with lattice parameters a=5.752 Ab=4.526 Ac=5.382 Aα=90 β=122.60 γ=90 . Precise control of synthesis parameters is required in stabilizing pure phase in bulk as well as thin lm form. This study focuses on the novel large scale two step synthesis of VO2 using Solution Combustion Synthesis. This involves synthesis of product utilizing redox reaction between metal nitrate and suitable fuel. Generally the products are nanocrystalline in nature due to self-propagation of the exothermic combustion reaction. First step involved the synthesis of V2O5 by combustion reaction between Vanadyl nitrate and urea. In the second step, the as-synthesized V2O5 has been reduced by a novel reduction technique to form monophasic VO2. The presence of competing phases like M1, M2, M3 and R are investigated by XRD, Raman spectroscopy, DSC, Optical and high temperature X-ray diffraction. Chapter IV deals with the reduction in phase transition temperature by doping the SCS synthesized VO2 with W and Mo. Effect of doping on the transition temperature was studied using differential scanning calorimetry (DSC) in both W and Mo. Electrical characteristics of Mo doped VO2 and Optical characteristics of the W-doped VO2 were also studied using four probe resistivity measurements and UV-VIS Spectroscopy respectively. W addition was found to be more effective in reducing the phase transition temperature. To understand further more on the W addition, X-ray photo-electron spectroscopy measurements were performed. W-addition alters the V4+-V4+ bonding and with W addition it is observed that V was present in V3+state. W was present in W6+ state. The addition of W to VO2 introduces more electrons to the systems and disturbs the V4+-V4+ thus reducing the phase transition temperature of VO2. Chapter V describes the large scale, large area deposition of thin films of VO2 by a cost effective method. A novel technique to deposit vanadium dioxide thin films namely, UNSPACM is developed. This simple two-step process involves synthesis of a V2O5 lm on an LaAlO3(LAO) substrate followed by a controlled reduction to form single phase VO2. The formation of M1 phase (P21/c) is confirmed by Raman spectroscopic studies. A thermally activated metal{insulator transition (MIT) was observed at 61 oC, where the resistivity changes by four orders of magnitude. The infrared spectra also show a dramatic change in reflectance from 13% to over 90% in the wavelength range of 7-15 m. This indicates the suitability of the films for optical switching applications at infrared frequencies. A trilayer metamaterial absorber, composed of a metal structure/dielectric spacer/vanadium dioxide (VO2) ground plane, is shown to switch reversibly between reflective and absorptive states as a function of temperature. The VO2 lm, which changes its conductivity by four orders of magnitude across an insulator{metal transition, enables the switching by forming a resonant absorptive structure at high temperatures while being inactive at low temperatures. The fabricated metamaterial shows a modulation of the reflectivity levels of 58% at a frequency of 22.5 THz and 57% at a frequency of 34.5 THz. Chapter VI explains the W doped VO2 thin films synthesized by UN-SPACM. Morphology of the thin films was found to be consisting of globular and porous nanoparticles having size 20 nm. Transition temperature decreased with the addition of W. 1.8 at. %W doping in VO2 transition temperature has reduced upto 25 oC. It is noted that W-doping in the pro-cess of reducing the transition temperature, alters the local structure and also increases room temperature carrier concentration. The presence of W, as was seen in Chapter IV, altered V4+-V4+ bonds and introduced V3+. W was found to be in W6+ state suggesting W addition increased the carrier concentration. Hall Effect measurements suggested the increased carrier con-centration. The roughness of the synthesized films were very high for them to be of de-vice quality, despite encouraging results obtained by electrical measurements. Hence in order to further improve the smoothness and thereby the optical quality of thin films, Chemical Vapour Deposition (CVD) is employed. Chapter VII outlines the effect of processing parameters and post pro-cessing annealing on the semiconductor-metallic transition of VO2. Here in this chapter, the influence of substrate temperature on the SMT properties of VO2 is explored. At different substrate temperatures, the percentage of phase fraction of V in V3+, 4+ and V5+ differed. Besides, the morphology also varied with substrate temperatures. Similarly it is observed that with annealing the VO2 film deposited on glass substrates, SMT properties enhanced which was attributed to filling out of oxygen vacancies. Si based substrates and non-Si based substrates were used for depositing VO2 thin films by CVD. Their temperature coefficient of resistance and SMT properties were studied in order to understand their potential in bolometer and thermal to optical valve based applications. Chapter VIII involves the study of VO2 thin films for thermal to optical valves. ITO coated glass substrates were used for the purpose. Thin films were deposited by both UNSPACM and CVD. It was observed that the reflectivity pro les of the films synthesized by the above said methods were very different. Hence in the process of understanding the huge difference in the reflectivity pro les, classical harmonic oscillator, Lorentzian model was employed to t the experimental data at room temperature whereas Drude-Lorentzian model was used to t the data at higher temperature (at 100 oC- after transition). With this fitting plasma frequencies of the CVD films were calculated. It was observed that defect chemistry of films synthesized by these methods were different. In order to further improve the smoothness of the films, microwave method was proposed in Chapter IX. The preliminary results showed the presence of uniform spheres and 3 D hierarchical structures of VO2 consisting of nanorods. This was extended to deposit VO2 thin films on ITO. DSC and Infrared reflectance pro le of VO2 nanopowder suggested the phase transition. Chapter X summarizes the work done for the thesis and provides insights to the applications and to the future work. The work reported in this thesis has been carried out by the candidate as part of the Ph.D.program. She hopes that this would constitute a worth-while contribution towards development of VO2 thin film technology and its challenges for reliable infrared device applications.
119

Monitoring teploty / Temperature Monitoring

Kotačka, Aleš January 2008 (has links)
This master's thesis deals use FITkit for longtime temperature monitoring without necessity connection on PC. Describe possibilities connection different heat-sensitive elements to FITkit inclusive physical realization. Further this thesis deals with measuring of temperature, displaying temperature and saving to memory, blocks-partitioning of memory. Is defined communication protocol between FITkit and PC for bulk downloading of data. So are solving problems with saving measure data to text files and next processing in table processors.
120

Internet of Things in Surface Mount TechnologyElectronics Assembly / Sakernas Internet inom Ytmontering av Elektronik

Sylvan, Andreas January 2017 (has links)
Currently manufacturers in the European Surface Mount Technology (SMT) industry seeproduction changeover, machine downtime and process optimization as their biggestchallenges. They also see a need for collecting data and sharing information betweenmachines, people and systems involved in the manufacturing process. Internet of Things (IoT)technology provides an opportunity to make this happen. This research project gives answers tothe question of what the potentials and challenges of IoT implementation are in European SMTmanufacturing. First, key IoT concepts are introduced. Then, through interviews with expertsworking in SMT manufacturing, the current standpoint of the SMT industry is defined. The studypinpoints obstacles in SMT IoT implementation and proposes a solution. Firstly, local datacollection and sharing needs to be achieved through the use of standardized IoT protocols andAPIs. Secondly, because SMT manufacturers do not trust that sensitive data will remain securein the Cloud, a separation of proprietary data and statistical data is needed in order take a stepfurther and collect Big Data in a Cloud service. This will allow for new services to be offered byequipment manufacturers. / I dagsläget upplever tillverkare inom den europeiska ytmonteringsindustrin för elektronikproduktionsomställningar, nedtid för maskiner och processoptimering som sina störstautmaningar. De ser även ett behov av att samla data och dela information mellan maskiner,människor och system som som är delaktiga i tillverkningsprocessen.Sakernas internet, även kallat Internet of Things (IoT), erbjuder teknik som kan göra dettamöjligt. Det här forskningsprojektet besvarar frågan om vilken potential som finns samt vilkautmaningar en implementation av sakernas internet inom europeisk ytmonteringstillverkning avelektronik innebär. Till att börja med introduceras nyckelkoncept inom sakernas internet. Sedandefinieras utgångsläget i elektroniktillverkningsindustrin genom intervjuer med experter.Studien belyser de hinder som ligger i vägen för implementation och föreslår en lösning. Dettainnebär först och främst att datainsamling och delning av data måste uppnås genomanvändning av standardiserade protokoll för sakernas internet ochapplikationsprogrammeringsgränssnitt (APIer). På grund av att elektroniktillverkare inte litar påatt känslig data förblir säker i molnet måste proprietär data separeras från statistisk data. Dettaför att möjliggöra nästa steg som är insamling av så kallad Big Data i en molntjänst. Dettamöjliggör i sin tur för tillverkaren av produktionsmaskiner att erbjuda nya tjänster.

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