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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.
31

O PIBID e o papel das trÃades formativas na formaÃÃo inicial e continuada de professores de ciÃncias: a formaÃÃo de professores de quÃmica em questÃo / The PIBID and the role of training triads in initial and continuing training of science teachers: the formation of chemistry teachers in question

JOYCE MELO MESQUITA 18 March 2015 (has links)
O Ensino de CiÃncias/QuÃmica apresenta uma importante funÃÃo no desenvolvimento da sociedade contemporÃnea, pois possibilita uma leitura de mundo necessÃria para a melhoria da relaÃÃo do homem com seu gÃnero e o meio ambiente. Neste sentido, destaca-se o papel do professor de CiÃncias/QuÃmica, sua funÃÃo social na construÃÃo do conjunto de saberes necessÃrio ao exercÃcio da cidadania. à contramÃo da importÃncia do referido ensino e de seu profissional encontram-se os cursos de formaÃÃo inicial de professores de CiÃncias/QuÃmica que, de forma deficiente, impedem uma formaÃÃo afinada Ãs urgÃncias da educaÃÃo bÃsica, pois trabalha no tipo ideal de uma sala de aula desejÃvel, ignorando problemas e desafios de um saber que cada vez mais se complexifica para fazer frente Ãs demandas do mundo contemporÃneo. DaÃ, a formaÃÃo inicial de professores de ciÃncias tem se apresentado deficiente para assumir tal desafio, pois ainda està ancorado na ideia de que a atividade docente à simples, requerendo tÃo somente um conjunto de saberes especÃficos de um campo de saber para executÃ-la. Tal diagnÃstico tem colocado duas teses como campos antagÃnicos da consideraÃÃo da formaÃÃo de professores de ciÃncias, a saber: a racionalidade tÃcnica e a racionalidade prÃtica. A racionalidade tÃcnica à marcada por uma visÃo reduzida do processo de formaÃÃo de professores ancorada na combinaÃÃo de conhecimentos do conteÃdo e de algumas prÃticas pedagÃgicas. Jà a racionalidade prÃtica compreende o professor como um pesquisador de sua atividade que, atravÃs do diÃlogo com seus pares, à capaz de orientar suas aÃÃes futuras em um constante processo de aÃÃo-reflexÃo, logo um professor autÃnomo e crÃtico/reflexivo. Neste contexto, este trabalho buscou investigar o papel do PIBID e das trÃades formativas em aÃÃes de formaÃÃo inicial e continuada para professores de CiÃncias/QuÃmica da rede bÃsica de ensino da cidade de Sobral (CE), professores formadores da Universidade Estadual Vale do Acaraà â UVA e Licenciandos do subprojeto interdisciplinar do PIBID/UVA. Para tanto, reuniu os trÃs atores citados em atividades de formaÃÃo (oficinas e grupos de estudo) visando o desenvolvimento de uma racionalidade prÃtica. A investigaÃÃo se pautou pelo uso dos mÃtodos dedutivo e indutivo. O primeiro à caracterizado pela pesquisa bibliogrÃfica. O segundo se referiu à pesquisa de campo. As anÃlises utilizadas se referenciaram por uma abordagem qualitativa. Quanto ao nÃvel a pesquisa se caracterizou como descritiva e com uso das tÃcnicas da pesquisa participante. As tÃcnicas de pesquisa utilizadas foram questionÃrios, entrevistas semi-estruturadas e o uso da observaÃÃo participante e sistemÃtica, atravÃs do registro em diÃrio de bordo. Os resultados evidenciam (a) o potencial das trÃades formativas, inseridas no contexto do PIBID, para aproximar a universidade da escola; (b) potencializa a formaÃÃo inicial a uma perspectiva mais afinada à realidade da educaÃÃo bÃsica; (c) fortalece nas instituiÃÃes (Universidade/Escola) parcerias formativas que tomam o empÃrico da sala de aula como espaÃo formativo e reflexivo. / The teaching of Science/ Chemistry present an important function in the development of the modern society, so it enables a necessary world reading in order to improve the relation between men and its gender and his environment. In this sense stands out the role of the Science/Chemistry teacher, his role in the building of necessary knowledge with the purpose of putting the citizenship. On the other hand of the importance of the referred teaching and his professional it can be found the initial Science/ Chemistry teachers training courses that, in an defective way, impedes a well made training at the urgency of basic education, since it works in a desirable classroom, ignoring the problems and challenges of a knowledge that is getting more and more difficult to the modern world demanding. So, the initial science teachers training has been presented defective to face that challenge, since it is still based on the idea that the teachers role is simple, requiring just a specific group of knowledge field to put it into practice. This diagnostic has put two theses as opposite fields in the understanding of the science teachers training: technical rationality and practical rationality. The technical rationality is characterized as a reduced view of the teachers training process anchored in the knowledge combination of the contents and some pedagogical practices. Then the practical rationality understands the teacher as a researcher of his practice, that through the dialogue with his workmates, he is able to guide his future actions in a reflection-action, so a reflexive/ critical. On this context, this project looked for to investigate the PIBID roll training triads in initial and continuing training activities for teachers of science/ chemistry teaching basic network, educators from Vale do Acaraà State University (UVA) and undergraduate students from PIBID\\UVA. So it got together three actors, which it was mentioned (workshop and learning circle) aiming the development of rationality practice, the investigation used the deductive and inductive. The first one is characterized by the bibliographic research. The second one is related to field research. The analyzes used made reference to a qualitative approach. Related to the research level it was characterized as descriptive and using techniques of the research. The researches techniques used were questionnaires, interviews and the use of active observation and systematic, through a registration in a boarding agenda. The results shows the potential of training triads, which are inserted in the PIBID context, in order to bring closer the university and school; (b) enhance the initial training to a better perspective to the basic education reality; (c) strengthen in institutions (university/school) training partnership which understand the classroom as a formative and reflexive space.
32

"Interação não-linear entre ondas atmosféricas: um possível mecanismo para a conexão trópicos-extratrópicos em baixa-frequência" / Nonlinear interaction among atmospheric waves: a possible mechanism for the tropics-extratropics connection on low-frequency time-scales.

Carlos Frederico Mendonça Raupp 07 April 2006 (has links)
A teoria da perturbação baseada em múltiplas escalas temporais é usada neste trabalho para estudar as interações não lineares entre ondas na atmosfera no contexto das equações primitivas no plano beta-equatorial em coordenadas isobáricas. As ondas equatoriais de Rossby, mista Rossby-gravidade, gravidade-inerciais e Kelvin, com diferentes estruturas verticais, são obtidas como soluções de ordem dominante. A partir da condição de solvabilidade do problema de ordem superior, foi obtido um modelo assintótico reduzido que governa a interação fracamente não linear entre as ondas numa determinada tríade ressonante. A conservação da energia total para a solução de ordem dominante do modelo de equações original implica que a soma dos coeficientes de interação numa tríade ressonante qualquer deve ser nula. Usando um método gráfico, foram encontradas algumas tríades ressonantes envolvendo ondas baroclínicas equatorialmente confinadas e ondas de Rossby barotrópicas possuindo significativa influência em médias e altas latitudes. Duas tríades ressonantes receberam especial atenção devido ao significativo acoplamento entre os modos e à possível relação desses modos com alguns aspectos observados acerca dos fenômenos de baixa freqüência na atmosfera. A primeira tríade é composta por uma onda de Rossby barotrópica possuindo o segundo modo meridional interagindo ressonantemente com uma onda mista de Rossby-gravidade com a estrutura vertical do primeiro modo baroclínico, ambas possuindo o mesmo número de onda zonal, por meio de um modo geostrófico zonalmente simétrico (k = 0) possuindo a mesma estrutura vertical da onda mista e o modo meridional n = 1. A segunda tríade é constituída por uma onda mista de Rossby-gravidade com número de onda-2, uma onda de Kelvin com número de onda-1, ambas associadas ao primeiro modo baroclínico, e uma onda de Rossby barotrópica com número de onda-3 e modo meridional n = 2. A integração das equações reduzidas para essas duas tríades ressonantes mostra que para as amplitudes iniciais dos modos caracterizando magnitudes típicas de anomalias atmosféricas observadas, os modos na primeira tríade, em geral, trocam energia na escala intra-sazonal, enquanto os modos na segunda tríade trocam energia na escala intra-sazonal ou numa escala semi-anual, dependendo da amplitude inicial do modo de Rossby barotrópico. São discutidas as implicações dos resultados para a dinâmica da interação trópicos-extratrópicos na escala de baixa-freqüência do espectro dos movimentos atmosféricos. / The asymptotic perturbation theory based on multiple scales in time is used to investigate the nonlinear interactions among equatorial waves in an equatorial beta-plane adiabatic primitive equation atmospheric model in isobaric coordinates. The equatorial Rossby, mixed Rossby-gravity, Kelvin and inertio-gravity waves, with several vertical structures, are obtained as the leading-order solution. From the solvability condition of the problem, a reduced model governing the weakly nonlinear interaction of the waves in a particular resonant triad was obtained. The total energy conservation of the leading-order solution of the original model equations implies that the sum of the coupling coefficients in any resonant triad must be zero. Using a graphical approach, we determined some resonant triads involving equatorially trapped baroclinic waves and barotropic Rossby waves having large mid-latitude amplitude. Two particular interactions deserve special attention because of their strong coupling and their possible relation to observed features in the atmospheric circulation. One is characterized by a first baroclinic mode structure mixed Rossby-gravity wave interacting with a barotropic Rossby wave with the second gravest meridional mode, both having the same wavenumber, through a zonally symmetric geostrophic mode with the same vertical structure as the Yanai wave and having the n = 1 meridional mode. The other triad is composed of a zonal wavenumber-1 Kelvin wave, a zonal wavenumber-2 mixed Rossby-gravity wave, both with the first baroclinic mode vertical structure, and a barotropic zonal wavenumber-3 Rossby wave having the second gravest meridional mode. The barotropic Rossby waves in these two triad interactions have significant projection onto middle and higher latitudes. The integration of the triad equations for these particular interactions shows that, for the initial mode amplitudes characterizing typical magnitudes of atmospheric flow perturbations, the modes in the first triad usually exchange energy on intraseasonal time-scales, while the modes in the second triad exchange energy on either intraseasonal or semi-annual time-scale, depending on the initial condition. The implications of the results for the dynamics of tropics-extratropics interaction on low-frequency time-scales are discussed.
33

Triarylborane Functionalized Dicyanovinyl and Acetylacetone Based Molecular Platforms : Building Blocks for Multiple Anion Sensors and Efficient Phosphorescence Emitters

Rajendra Kumar, G January 2016 (has links) (PDF)
Triarylborane Functionalized Dicyanovinyl and Acetylacetone Based Molecular Platforms: Building Blocks for Multiple Anion Sensors and Efficient Phosphorescence Emitters The main objective of this thesis is to design a simple strategy for triarylborane based multiple anion sensors and development of triarylborane incorporated phosphorescent metal complexes. The thesis consists of eight chapters and the contents of each chapter are given below. Chapter 1 This chapter gives a general introduction to recent advances relevant to the theme of the thesis. A review of the fundamental characteristics of triarylboranes and their applications in various fields such as chemical sensors and optoelectronics is presented. Advances in boron chemistry in the areas such as anion sensors, solid state emissive and phosphorescence materials are discussed in detail. The scope of the thesis is outlined at the end of the chapter. Chapter 2 The second chapter deals with the general experimental techniques and synthetic procedures followed in this thesis. Chapter 3 This chapter deals with a rational design strategy for differential identification of fluoride and cyanide ions using TAB based sensors. In general, most of the triarylboranes give similar optical responses towards fluoride and cyanide ions as they follow similar sensing mechanism. In order to circumvent this problem, two TAB-DCV conjugates (1 and 2) are designed and synthesised. The DCV unit is highly specific for cyanide ion owing to the presence of electrophilic carbon center. Probes 1 and 2 differ in steric crowding around the boron center. The less crowded boron center in 1 binds with fluoride as well as with cyanide ions giving similar optical response (luminescence is quenched in presence of F¯ and CN¯). In the case of 2, selectivity of boron center towards fluoride is tuned by increasing the steric crowding around the boron unit. The dicyanovinyl unit acts as selective sensing site for cyanide ions. As a result, 2 gives different fluorogenic response towards the anions F¯ and CN¯ which were considered as interfering anions in TAB based sensor chemistry. Thus, a modular design principle is developed for differential identification of fluoride and cyanide ions using TAB. Chapter 4 In this chapter, detailed photophysical studies of TAB-amine-DCV conjugates and colorimetric discrimination of fluoride and cyanide ions are discussed. Presence of amine based donor between the two electron deficient sites enhances the electronic conjugation in 3−5. Since there are two different acceptor sites with a common donor, two distinct charge transfer transition bands are observed in the visible region of electromagnetic spectrum. The absorption and emission spectra of these compounds show pronounced sensitivity to solvent polarity, signifying large excited state dipolmonents. Anion binding studies confirms that these compounds are highly selective towards fluoride and cyanide ions. Fluoride ions selectively interact with boron center and block the corresponding charge transfer transition thereby leading to a distinct colour change which is observable by naked eye. On the other hand, cyanide interacts with boron as well as DCV unit and blocks both the charge transfer transitions which results in disappearance of colour. Hence, compounds 4 and 5 exhibit different colorimetric signals for fluoride and cyanide ions. Since the absorption bands of 3 do not fall in the visible region, it does not show any colorimetric response towards the aforementioned anions. The anion sensing mechanisms are established by 1H, and 19F NMR studies. Chapter 5 This chapter presents a systematic study of the effect of length of π-electronic conjugation on the optical properties and anion sensing abilities of a series of TAB-oligothiophene-DCV conjugates (6−8). Their absorption as well as emission bands undergo redshift upon increasing the number of thiophene units between TAB and DCV units as the π-electronic conjugation in 6−8 is greatly dependent on the number of thiophene units. Their fluorescence emission is highly sensitive to solvent polarity. In the case of 6, the emission band undergoes a redshift with reduced intensity. In the case of 7 the emission band undergoes a redshift but the intensity is not affected by solvent polarity. In the case of 8, the emission band undergoes redshift with enhanced intensity in polar solvents. Interestingly, 7 and 8 show solvent viscosity dependent fluorescence. Structural reorganisation is restricted in viscous medium and results in enhanced emission for 7 and 8. Further, these compounds exhibit selective response towards the fluoride and cyanide ions with different colorimetric responses. Test strips made up of probes 7 and 8 have potential application in identifying fluoride and cyanide ions in aqueous medium. Chapter 6 This chapter describes synthesis and optical characterisation of triarylborane incorporated acetylacetone (acacH) ligands (9, 10) and their borondifluoride complexes (11, 12). AcacH ligands and BF2 complexes show solvent dependent emission phenomena due to the involvement of charge transfer transition. Their optical properties are highly dependent on molecular conformations. Complex with duryl spacer (12) exhibits more red shifted emission in polar solvents due to the enhanced charge transfer transition facilitated by twisted rigid geometry. In presence of fluoride and cyanide ions, the borondifluoride complexes are not stable. The anions concomitantly interact with tricoordinate boron as well as acac-BF2 unit to give rise to complex pattern of photoluminescence spectral changes during the titration experiment. The binding pathway and the possible species involved are established with the help of 1H, 19F and 11B NMR spectral studies in presence of the anions. Complexes 11 and 12 act as selective chemodosimetric sensors for fluoride and cyanide ions. Chapter 7 In this chapter, the synthesis and optical characterisations of triarylborane conjugated cyclometalated platinum complexes are discussed. A series of square planar platinum complexes are synthesised with different cyclometalating ligands. Complexes (13−18) exhibit a range of luminescence from green to red in solution as well as in the solid state. Their emission intensities are highly sensitive towards atmospheric oxygen suggesting that they originate from a triplet excited state. A maximum of 85% quantum yield is observed for complex 15 in solution state while complex 14 showed a maximum of 58% quantum yield in solid state. Complexes with rigid molecular conformation (14, 16 and 18) showed higher luminescence quantum yield than those having phenyl spacer (13, 15 and 17). The sterically encumbered boryl (-BMes2) group significantly reduces π-π stacking between the square planar entities. Thus, complexes 13−18 show bright luminescence in solid state compared to model complexes without boryl group. The effect of Lewis acidic boron center on luminescence behaviour is explored by fluoride binding studies. Chapter 8 This chapter is divided into two parts. Part-I describes the synthesis and optical characterisation of triarylborane conjugated cyclometalated iridium complexes (19−24). They are brightly luminescent in solution state with high sensitivity towards atmospheric oxygen. Complex 20 shows a highest quantum yield of 91%. Interestingly, under ambient atmospheric conditions, they exhibit a rare type of dual emission. Life time data suggest that the lower energy emission band originates from cyclometalated iridium based triplet excited state while higher energy emission band originates from boryl ased singlet excited state. Fluoride binding at the boron site results in luminescence quenching; evidently, tri-coordinate boron has a major contribution to the luminescence features of these iridium complexes. Part-II deals with synthesis of triarylborane conjugated pyrazole ligand (25) and its binuclear iridium complexes (26−28) in which two iridium centers are bridged by hydroxo as well as pyrazolato ligands. These binuclear iridium complexes exhibit higher luminescence quantum yield than TAB-acac-Iridium complexes (mononuclear complexes; part I). Binding of fluoride ions at the boron center has a minor impact on their luminescence nature. High sensitivity of their luminescence towards atmospheric oxygen indicates the involvement of triplet excited state in their emission process.
34

"Eyre," a Three Movement Instrumental Work for Small Chamber Ensemble

Hodges, Glen J. (Glen John) 05 1900 (has links)
"Eyre" is a composition of approximately sixteen minutes duration for an instrumental ensemble consisting of two flutes, oboe, B𝄭 clarinet, bassoon, guitar, and cello. It is inspired by a large seasonal lake basin in South Australia of the same name. The piece is divided into three movements; the first is fast and quasi sonata-allegro form without the recapitulation; the second is slow and through-composed; and the third, essentially the missing recapitulation from the first movement. Much of the motivic material for the piece is derived from the initial progression of triads. Harmonic and melodic development of this material contains some modal tendencies. While the overall effect tends toward equal weighting of the instrumental forces, there is some featuring of the guitar and an interplay between the woodwind and string instruments.
35

How school social workers define the problem and their roles in managing the problem: pupils' involvement intriad activities

Leung, Chun-ping, Tony., 梁振萍. January 1994 (has links)
published_or_final_version / Criminology / Master / Master of Social Sciences
36

Parametric Interaction in Josephson Junction Circuits and Transmission Lines

Mohebbi, Hamid Reza 06 November 2014 (has links)
This research investigates the realization of parametric amplification in superconducting circuits and structures where nonlinearity is provided by Josephson junction (JJ) elements. We aim to develop a systematic analysis over JJ-based devices toward design of novel traveling-wave Josephson parametric amplifiers (TW-JPA). Chapters of this thesis fall into three categories: lumped JPA, superconducting periodic structures and discrete Josephson transmission lines (DJTL). The unbiased Josephson junction (JJ) is a nonlinear element suitable for parametric amplification through a four-photon process. Two circuit topologies are introduced to capture the unique property of the JJ in order to efficiently mix signal, pump and idler signals for the purpose of signal amplification. Closed-form expressions are derived for gain characteristics, bandwidth determination, noise properties and impedance for this kind of parametric power amplifier. The concept of negative resistance in the gain formulation is observed. A design process is also introduced to find the regimes of operation for gain achievement. Two regimes of operation, oscillation and amplification, are highlighted and distinguished in the result section. Optimization of the circuits to enhance the bandwidth is also carried out. Moving toward TW-JPA, the second part is devoted to modelling the linear wave propagation in a periodic superconducting structure. We derive closed-form equations for dispersion and s-parameters of infinite and finite periodic structures, respectively. Band gap formation is highlighted and its potential applications in the design of passive filters and resonators are discussed. The superconducting structures are fabricated using YBCO and measured, illustrating a good correlation with the numerical results. A novel superconducting Transmission Line (TL), which is periodically loaded by Josephson junctions (JJ) and assisted by open stubs, is proposed as a platform to realize a traveling-wave parametric device. Using the TL model, this structure is modeled by a system of nonlinear partial differential equations (PDE) with a driving source and mixed-boundary conditions at the input and output terminals, respectively. This model successfully emulates parametric and nonlinear microwave propagation when long-wave approximation is applicable. The influence of dispersion to sustain three non-degenerate phased-locked waves through the TL is highlighted. A rigorous and robust Finite Difference Time Domain (FDTD) solver based on the explicit Lax-Wendroff and implicit Crank-Nicolson schemes has been developed to investigate the device responses under various excitations. Linearization of the wave equation, under small-amplitude assumption, dispersion and impedance analysis is performed to explore more aspects of the device for the purpose of efficient design of a traveling-wave parametric amplifier. Knowing all microwave characteristics and identifying different regimes of operation, which include impedance properties, cut-off propagation, dispersive behaviour and shock-wave formation, we exploit perturbation theory accompanied by the method of multiple scale to derive the three nonlinear coupled amplitude equations to describe the parametric interaction. A graphical technique is suggested to find three waves on the dispersion diagram satisfying the phase-matching conditions. Both cases of perfect phase-matching and slight mismatching are addressed in this work. The incorporation of two numerical techniques, spectral method in space and multistep Adams-Bashforth in time domain, is employed to monitor the unilateral gain, superior stability and bandwidth of this structure. Two types of functionality, mixing and amplification, with their requirements are described. These properties make this structure desirable for applications ranging from superconducting optoelectronics to dispersive readout of superconducting qubits where high sensitivity and ultra-low noise operation is required.

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