Tesis sobre el tema "Cold Bridge"

Thesis (M.A. in Security Studies (Europe, Eurasia))--Naval Postgraduate School, December 2008.
Thesis Advisor(s): Siegel, Scott. "December 2008." Description based on title screen as viewed on January 29, 2009. Includes bibliographical references (p. 67-74). Also available in print.

The 1950s saw the height of the Beat literature movement. Within this movement moved a cohort of women who helped revolutionize gender relations in the early Cold War era, leading to the emergence of the women's liberation movement of the 1960s and 1970s. By questioning social gender norms and harnessing their artistic, sexual, and economic autonomy, Beat women built lives of lived art outside proscribed social norms building the base for a new era in gender relations.

Master of Science
Department of Civil Engineering
Robert Peterman
A flowable hybrid concrete mix with a spread of 17 to 20 inches was created with a superplasticizer to be used in post-tension haunch-slab (PTHS) bridges where rebar congestion is heaviest. The mix would allow for proper concrete consolidation. A conventional concrete mix with a slump of three to four inches was also created to be placed on top of the hybrid mix. The conventional mix would be used to create a sloping surface on the top of the concrete. The two mixes could be combined in the PTHS bridge deck and act as one monolithic specimen. Standard concrete tests such as compressive strength, tensile strength, modulus of elasticity, permeability, freeze/thaw resistance, and coefficient of thermal expansion were determined for the mixes and compared. Core blocks were cast using both mixes and composite cores were drilled. The cores were tested and their composite split-tensile strengths were compared to the split-tensile strengths of cylinders made from the respective mixes. A third concrete mix was made by increasing the superplasticizer dosage in the hybrid concrete mix to create a self-consolidating concrete (SCC) mix with a 24-inch spread. The SCC mix was created as a worst-case scenario and used in the determination of shear friction. Eighty-four push-off shear friction specimens were cast using the SCC mix. Joint conditions for the specimens included uncracked, pre-cracked, and cold-joints. Uncracked and pre-cracked specimens used both epoxy- and non-epoxy-coated shear stirrups. Cold-joint specimens used both the SCC mix and the conventional concrete mix. Joint-conditions of the cold-joint specimens included a one-hour cast time, a seven-day joint with a clean shear interface, and a seven-day joint with an oiled shear interface. The shear friction specimens were tested using a pure shear method and their results were compared to the current American Concrete Institute code equation.

Abstract. The fast-fashion industry has experienced pressure due to creating unsustainable impacts on the environment and society. Sustainability impacts of the fast-fashion industry have called for the necessity of sustainable fashion consumption and ethical production of fashion-clothes. Despite being concerned about sustainability, consumers usually show reluctant-behavior to adopt ethical changes in their fashion consumption patterns. This study investigates consumers’ attitude-behavior gap in sustainable fashion consumption, identifies reasons for the gap’s existence, and suggests possible ways to bridge the gap. The theoretical framework for this thesis is formed based on the pieces of evidence found in previous researches regarding sustainable consumerism. In order to serve the research purpose, this thesis is conducted based on a qualitative research design. Furthermore, this study adopts an abductive reasoning approach throughout the research process. Interviews and Focus Group Discussions are conducted to collect primary data. Target population mostly consists of female students and the age group is 20–35. The finding of the study reveals that the attitude-behavior gap can never be eliminated completely but the gap can be minimized through taking adequate actions. Several individual, social, and situational factors influence the size of the attitude-behavior gap in sustainable fashion consumption. Another finding suggests possible ways to bridge the gap from four perspectives; companies’ side, policymakers’ side, consumers’ side, and joint efforts by companies, consumers, and policymakers.

The Japanese Emperor Hirohito accepted the Potsdam Declaration on 14 August 1945 represented the Japanese government announced the unconditional surrender. Based on the declaration, the process of the Allied occupation of Japan from 1945 to 1952 started. The period from 1945 to 1952 was special not only because it was the time of the allied occupation of Japan and also the period of Cold War. Japan as a defeated country in the WWII was occupied and the U.S. government had a special role in Japan. The Supreme Commander for the Allied Power (SCAP) had critical role in Japan in this period and it marked the change of Japan and the U.S. also made important change on the immigration policy. The U.S. occupation allowed the interracial marriage between the G.I.s and the Japanese women. Japanese war bride was the product of the occupation. They witnessed the immigration law reform, the racial problem in the society and the cooperation during the cold war. In this paper, I argue that Japanese war brides as the subject in the reform of the immigration laws. The implementation of different public laws, from only allowing non-Asia war brides to open to all war brides within the deadline show the improvement in the racial limitation requirement. The Immigration and Nationality Act of 1952 and 1965 further reduced and eliminated the national origins quotas. Asians can therefore immigrate to the U.S. I also explain the racial ideas in the U.S. society by analyzing the bride schools. The war brides were encouraged to participate in the bride school before leaving Japan. They learned the history of the U.S., the culture and society of the U.S. and other skills as housewives and mothers. They were trained to match with the expectation of the U.S. society. I also analyze “assimilationism” and immigration policies. The “assimilation” of the Japanese war brides in Bride school can represent the ideology of immigration in the situation of the postwar society. The immigration laws before 1965 still contained the national origins ideas, which the Soviet Union used to attack and criticize. However, the U.S. occupation allowed the cooperation with the Japanese government. The “assimilation” of the Japanese war brides provided a special scene in showing the encounter of “assimilationism” and immigration law reform. The Japanese war brides witnessed the change in the immigration laws, “assimilationism” and Cold War policies. The Japanese war brides were the subjects in viewing the reform of the immigration policies. Using them to review the process can provide a different angle to evaluate the Cold War situation.

Cooperation is a trait that is found at all levels of biological organization. Interestingly, cooperation appears to occur in bacteria that produce small, easily diffusible molecules called autoinducers. To understand why bacteria produce these autoinducers, the scientific community has focused on one predominant theory called quorum sensing. Under this theory, bacteria produce autoinducers so they can sense the density of the population. Once a sufficiently high population density is reached, autoinducers initiate the production of a costly gene product that serves to benefit the population. In contrast, a competing theory called diffusion sensing suggests that autoinducers are used by the individual cells and are not used for cooperation. Here, the production of the autoinducer serves as a mechanism to sense environmental conditions. If the environmental conditions are favorable, a costly gene product is produced. To what extent, and under what conditions, are each of these opposing theories valid remains to be identified. In this thesis, an engineered strain of Escherichia coli was used to identify the conditions under which quorum sensing and diffusing sensing can be observed. It was discovered that, depending upon the frequency at which the spatial distribution of the autoinducer and bacteria was disrupted, the population of engineered bacteria displayed hallmarks of either quorum sensing or diffusion sensing. Specifically, when the spatial distribution was disturbed at high or low frequency, quorum sensing was observed. However, when spatial distribution was disturbed at an intermediate frequency, diffusion sensing was observed. Understanding how these disturbances affect survival in bacteria may result in novel treatments for bacterial infections. In more general applications, it may be exploited in the development of alternative mechanisms for controlling invasive species or aid in species reintroduction.

Submitted by PPG Odontologia (odontologia-pg@pucrs.br) on 2018-03-19T17:50:17Z No. of bitstreams: 1 TAMARA_PALUDO_DIS.pdf: 786437 bytes, checksum: 24d142989a1f4e1aac8bb4a9d2a1548c (MD5)
Approved for entry into archive by Tatiana Lopes (tatiana.lopes@pucrs.br) on 2018-04-04T11:42:36Z (GMT) No. of bitstreams: 1 TAMARA_PALUDO_DIS.pdf: 786437 bytes, checksum: 24d142989a1f4e1aac8bb4a9d2a1548c (MD5)
Made available in DSpace on 2018-04-04T11:50:01Z (GMT). No. of bitstreams: 1 TAMARA_PALUDO_DIS.pdf: 786437 bytes, checksum: 24d142989a1f4e1aac8bb4a9d2a1548c (MD5) Previous issue date: 2018-01-10
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
(Artigo 1 Effect of a collagen stabilizing acid conditioner on adhesion to enamel and dentin) The aim was to evaluate the effect of different concentrations of phosphoric acid with grape seed extract (GSE) on the enamel acid etching, on the immediate bond strength to enamel, and on the bond strength to dentin after 12 months storage. Three different phosphoric acid formulations with GSE were obtained: GSE5 - 5% phosphoric acid + 20% ethanol + 2% GSE; GSE10 -10% phosphoric acid + 20% ethanol + 2% GSE; GSE20 - 20% phosphoric acid + 20% ethanol + 2% GSE; GC (control) - 37% phosphoric acid. The enamel and dentin surfaces of third molars, extracted for therapeutic reasons, were etched with 37% phosphoric acid for 15 s, and with the modified acids for 30 s. The acid was rinsed, followed by application of Adper Scotchbond Multipurpose adhesive system, and a block of composite resin was built. In enamel, the etching pattern was evaluated by scanning electron microscopy (SEM) and the bond strength was evaluated by conventional tensile test. In dentin, the microtensile bond strength (?TBS) was evaluated after 24 h and 1 year of storage. SEM images showed that GSE5 caused a more superficial enamel etching. According to ANOVA and Tukey?s test, enamel bond strength did not differ significantly between GC (49.00 MPa), GSE5 (42.78 MPa), GSE10 (51.55 MPa) and GSE 20 (36.18 MPa) (p> 0.05).According to two-way ANOVA and Tukey?s test, the interaction of factors (treatment x storage time) was significant (p=0.0001). At the 24 h of storage, GC (28.43 MPa) obtained the highest ?TBS, and did not differ significantly from GSE20 (24.11 MPa). GC and GSE20 were significantly higher to the others (p<0.05).The GSE10 (17.53 MPa) and GSE5 (16.75 MPa) did not differ significantly from each other. At the 12 months of storage, there was no significant difference in ?TBS between GC (17.71 MPa), GSE5 (20.97 MPa), GSE10 (17.59 MPa) and GSE20 (18.52 MPa). Only GSE5 and GSE10 did not significantly decrease ?TBS after 12 months of storage. It was concluded that GSE5 caused a more superficial enamel etching pattern in relation to the acid concentrations at 37%, 20% and 10%. However, there was no significant difference in the bond strength to enamel among the four concentrations. GSE5 and GSE10 promoted stability of the bond strength to dentin after 12 months of storage. (Artigo 2 Effect of phosphoric acid with polyphenols on dentin collagen : Atomic force microscopy study) Objective: The aim was of this study to evaluate the effect of different concentrations of phosphoric acid with grape seed extract (GSE) on the structure of the collagen fibrils of dentin. Materials and methods: Samples (0.3 mm thickness and 8 mm diameter) of the middle third of the coronal dentin of sound human molars were obtained. Half of the dentin of each tooth was etched with phosphoric acid (5%, 10%, or 20%) for 30 s, and the other half was etched with its corresponding phosphoric acid with 2% GSE for 30 s. The dentin of each sample was observed using an Atomic Force Microscope (AFM). Results: AFM images showed that phosphoric acid at concentrations of 5%, 10% and 20% demineralized the dentin and exposed the collagen fibrils and their pattern of periodicity. Phosphoric acid at each concentration with 2% GSE changed the collagen fibril periodicity, and the collagen fibrils formed globular structures. This change was more significant in dentin treated with 5% phosphoric acid and less significant with 20% phosphoric acid. Conclusions: The use of 5% phosphoric acid with 2% GSE produced denser collagenous globular structures. This conformational change in the collagen can make it more mechanically and enzymatically resistant.
(Artigo 1 Efeito de um condicionador ?cido estabilizador de col?geno na ades?o ao esmalte e ? dentina) O objetivo foi avaliar o efeito de diferentes concentra??es de ?cido fosf?rico com extrato de semente de uva (GSE) no padr?o de condicionamento ?cido em esmalte, na resist?ncia de uni?o imediata ao esmalte e ap?s 12 meses de armazenamento em dentina. Tr?s diferentes formula??es de ?cido fosf?rico com GSE foram obtidas: GSE5 - 5% de ?cido fosf?rico + 20% de etanol + 2% de GSE; GSE10 -10% de ?cido fosf?rico + 20% de etanol + 2% de GSE; GSE20 - 20% de ?cido fosf?rico + 20% de etanol + 2% de GSE; GC (controle) - ?cido fosf?rico 37%. As superf?cies do esmalte e da dentina de dentes terceiros molares, extra?dos por raz?es terap?uticas, foram condicionadas com ?cido fosf?rico 37% por 15 s e com os ?cidos modificados por 30 s, seguido de lavagem e aplica??o do sistema adesivo Adper Scotchbond Multiuso (convencional de tr?s passos) e da constru??o de um bloco em resina composta. Em esmalte, o padr?o de condicionamento foi avaliado em microscopia eletr?nica de varredura (MEV) e a resist?ncia de uni?o foi avaliada pelo ensaio de tra??o convencional. Em dentina, a resist?ncia de uni?o ? microtra??o (R?T) foi avaliada ap?s 24 h e 12 meses de armazenamento. As imagens em MEV evidenciaram que o GSE5 causou um condicionamento mais superficial do esmalte. De acordo com ANOVA de 2 fatores e Tukey, a resist?ncia de uni?o ao esmalte n?o diferiu estatisticamente entre GC (49,00 MPa), GSE5 (42,78 MPa), GSE10 (51,55 MPa) e GSE20 (36,18 MPa) (p>0,05). De acordo com ANOVA de duas vias e Tukey, a intera??o tratamento x tempo de armazenamento foi significativa (p=0,0001). No tempo de armazenamento de 24 h, GC (28,43 MPa) obteve a maior R?T, n?o diferindo estatisticamente do grupo GSE20 (24,11 MPa), sendo ambos estatisticamente superiores aos demais (p<0,05). O grupo GSE10 (17,53 MPa) e o GSE5 (16,75 MPa) n?o diferiram estatisticamente entre si. No tempo de armazenamento de 12 meses, n?o houve diferen?a estat?stica na R?T entre o GC (17,71 MPa), GSE5 (20,97 MPa), GSE10 (17,59 MPa) e GSE20 (18,52 MPa). Apenas GSE5 e GSE10 n?o tiveram redu??o significativa da R?T ap?s 12 meses de armazenamento. Concluiu-se que o GSE5 causou um condicionamento mais superficial do esmalte em rela??o ?s concentra??es de 37%, 20% e 10%. No entanto, n?o houve diferen?a estat?stica nos valores de resist?ncia ? tra??o imediata ao esmalte entre as quatro concentra??es. GSE5 e GSE10 promoveram a estabilidade da resist?ncia de uni?o ? dentina ap?s 12 meses de armazenamento.

Submitted by SBI Biblioteca Digital (sbi.bibliotecadigital@puc-campinas.edu.br) on 2018-03-15T13:19:19Z No. of bitstreams: 1 RENATA ELIZA PAVANELLO.pdf: 1818495 bytes, checksum: 584f82239d012d948febe192c32331a9 (MD5)
Made available in DSpace on 2018-03-15T13:19:20Z (GMT). No. of bitstreams: 1 RENATA ELIZA PAVANELLO.pdf: 1818495 bytes, checksum: 584f82239d012d948febe192c32331a9 (MD5) Previous issue date: 2018-02-02
The aim of this paper was to evaluate the influence of acid etching on the bond strength of the universal adhesive system in caries-affected-dentin. For this experimental study, 40 erupted permanent third molars were selected at the Dental Clinic of the PUC-Campinas with Free and Informed Consent Term signed by the patients. Removal of the occlusal third with double - sided diamond disc and flat dentin surfaces obtained by sanding was done. The lesion of the caries was developed by microbiological method with S. mutans strain ATCC25175. The teeth were divided into 4 groups (n = 10): AF-I: phosphoric acid conditioning and application of the Universal Single Bond adhesive system - immediate microtensile test; AF-DC: phosphoric acid conditioning and application of the Universal Single Bond adhesive system and microtensile test after cariogenic challenge; SAF-I: application of the Universal Single Bond adhesive system without acid etching and immediate microtensile test and SAF-DC: application of the Universal Single Bond adhesive system without acid etching and microtensile test after carig?nico challenge. A composite resin block was made in the affected dentin. Each tooth / adhesive / resin block was sectioned with diamond discs coupled to the Isomet cutting machine in parallel planes obtaining test pieces in the shape of sticks, with a cross-sectional area of 1 mm2. Microtensile test was performed. Only adhesive / mixed fractures were considered for bond strength calculation. The results were evaluated by the Kruskal-Wallis test (Student-Newman-Keuls) and Friedman. The higher bond strength occurred in the groups in which the phosphoric acid conditioning was done (p <0.05). There was no significant difference in union strength after cariogenic challenge (p> 0.05). The type of fracture was predominantly adhesive. It was concluded that phosphoric acid caused increased bond strength of the Universal Single Bond adhesive system in caries affected dentin and the cariogenic challenge did not interfere in the bond strength of the Universal Single Bond adhesive system in dentin affected by caries.
O objetivo deste trabalho foi avaliar a interfer?ncia do condicionamento ?cido na resist?ncia de uni?o do sistema adesivo universal na dentina afetada por c?rie. Para este estudo de car?ter experimental foram selecionados 40 terceiros molares permanentes erupcionados com Termo de Consentimento Livre e Esclarecido assinado pelos pacientes na Cl?nica Odontol?gica da PUC-Campinas. Foi feita a remo??o do ter?o oclusal com disco diamantado dupla face e superf?cies dentin?rias planas obtidas atrav?s de lixamento. A les?o de c?rie foi desenvolvida pelo m?todo microbiol?gico com cepa padr?o S. mutans ATCC25175. Os dentes foram divididos aleatoriamente em 4 grupos (n=10): AF-I: condicionamento com ?cido fosf?rico e aplica??o do sistema adesivo Single Bond Universal - teste imediato de microtra??o; AF-DC: condicionamento com ?cido fosf?rico e aplica??o do sistema adesivo Single Bond Universal e teste de microtra??o ap?s desafio cariog?nico; SAF-I: aplica??o do sistema adesivo Single Bond Universal sem condicionamento ?cido e teste imediato de microtra??o e SAF-DC: aplica??o do sistema adesivo Single Bond Universal sem condicionamento ?cido e teste de microtra??o ap?s desafio carig?nico. Um bloco de resina composta Charisma foi confeccionado na dentina afetada. Cada bloco dente/adesivo/resina foi seccionado com discos diamantados acoplados a m?quina de corte Isomet em planos paralelos obtendo corpos de prova em forma de palitos, com ?rea de sec??o transversal de 1 mm2. Para realiza??o do teste de microtra??o. Apenas fraturas adesivas /mistas foram consideradas para c?lculo de resist?ncia de uni?o. Os resultados foram avaliados pelo teste Kruskal-Wallis (Student-Newman-Keuls) e Friedman. A maior resist?ncia de uni?o ocorreu nos grupos em que foi feito o condicionamento com ?cido fosf?rico (p<0.05). N?o houve diferen?a significante na resist?ncia de uni?o ap?s o desafio cariog?nico (p>0.05). O tipo de fratura predominante foi adesiva. Pode-se concluir que o ?cido fosf?rico acarretou aumento na resist?ncia de uni?o do sistema adesivo Single Bond Universal na dentina afetada por c?rie e o desafio cariog?nico n?o interferiu na resist?ncia de uni?o do sistema adesivo Single Bond Universal na dentina afetada por c?rie.

碩士
國立臺灣大學
電子工程學研究所
95
The aim of this thesis is to study and implement a full-bridge phase-shifted driving circuit with current balancing for cold cathode fluorescent lamps. Because the impedance of each lamp in a traditional multi-lamp system is not necessarily the same, the current through each lamp would be dramatically different. Therefore, the brightness of the system is not uniformly distributed. The aim of this thesis is to utilize balancing transformers to reduce the current differences between each lamp such that the brightness of each lamp maintains uniform. The circuit architecture in the thesis is full-bridge phase-shifted inverter. It utilizes full-bridge phase-shifted pulse width modulation to achieve zero voltage switching and reduce the switching loss. In the end, a driving circuit for cold cathode fluorescent lamp is demonstrated and the experimental results can verify the theoretical analysis.

碩士
中原大學
電機工程研究所
96
The liquid crystal screen will not shine voluntarily, it needs a backlight module to laminate. This thesis focus on a high frequency inverter to drive CCFL to reach flexible brightness as well as the high efficiency, and discusses the balance method for multiple CCFLs driving. For this study, a full bridge inverter has been employed for less switching losses, component stresses, and electromagnetic interferences. For current-balance, Jin balancing method is adopted to avoid feedback circuit for each lamp. Finally, the test and measurement of this system is carried out to show its performance under different operating characteristics. And the experimental results confirm that it can fulfill the design purposes.

碩士
淡江大學
電機工程學系碩士在職專班
97
As technology developed rapidly, the size of the TFT-LCD panel grow larger and larger. Thus, the Cold Cathode Fluorescent Lamp (CCFL) contained became longer in length, and more in number. A low product cost solution has become a crucial issue for lifetime enterprise. The purpose of this paper is to use the full-bridge phase-shift quasi-resonant converter that allows zero voltage turn-on of switches. While retaining the merits of simple circuit and small size, it uses the parasitic components to resonate. Therefore, additional resonant components are not required. Moreover, the switching loss is reduced by the use of the zero voltage switching (ZVS) resonant technique. It uses phase-shift control to achieve the result. The transistor has the characteristic of zero voltage switching, using a transformer. A main combination of parasitic components, which includes the Metal Oxide Semiconductor Field Effect Transistor (MOSEFT) and second leakage inductance of the Isolation transformer, produces a resonant action and reduces drain-source voltage prior to turn-on. Moreover, it achieved high efficiency and increased Mean Time Between failure (MTBF). Finally, the OZ9938 controller IC manufactured by OZ Micr corp. is adopted in this thesis for use in 19” TFT-LCD with CCFLs from external light source, for the driver circuit of CCFL same as inverter, and introduced hardware aspects of the structure, so that readers understand quasi-resonant converter to the TFT-LCD of backlight unit application.

碩士
中原大學
電機工程研究所
92
Abstract In this thesis, a quasi-resonant inverter with high efficiency, low cost and simplified circuit scheme for the multiple cold cathode fluorescent lamps as the TFT-LCD backlight is presented. The proposed topology is phase-shift full-bridge quasi-resonant inverter. The design example is also presented. The proposed inverter is a one-stage phase-shift full-bridge quasi-resonant DC-AC power converter compared with the conventional two-stage current-fed push-pull DC-AC power converter and the component count can be reduced. The high efficiency of zero-voltage switching (ZVS) and zero-current switching (ZCS) technique is also provided to eliminate the switching losses of the power MOSFETs over the whole dimming range. A phase-shift modulation between the switches is optimized to regulate the CCFL power, and then the switching frequency and the switching duty cycle of the switches can be fixed at steady state. The design of secondary resonant tank circuit determines the resonant frequency and operating frequency. A sweeping frequency technique can be used to ignite the CCFLs by accounting for the parasitic capacitance and leakage inductance in the resonant tank circuit. The resonant tank also acts as a low-pass or band-pass filter after the CCFL is ignited, then the preferred sinusoidal operating voltage and current waveform can be provided to increase the lifetime and luminance of CCFLs. Additionally, for multiple CCFLs, a simplified resonant current balance circuit scheme is proposed for the single control loop DC-AC power inverter to reduce the total component count. Finally, a prototype circuit for 4 cold cathode fluorescent lamps is built and tested to verify the analytical prediction. The chief results of our work are shown below. (1) The single stage resonant inverter operates with high efficiency, and the thermal issue will be solved easily. (2) The current between multiple cold cathode fluorescent lamps can be balanced easily by the simplified resonant current balance circuit. (3) Sinusoidal and symmetric current and voltage waveforms are provided for the fluorescent lamps to increase its lifetime and luminance. (4) A low cost solution for multiple lamps backlight driver is proposed.

碩士
國立臺灣大學
地理環境資源學研究所
102
Kinmen has played a significant role in the development of cross-strait relations due to its complex political history and geo-spatiality. As a special field for cross-strait relations, this study uses Kinmen Kaoliang Liquor as an example to elaborate the flexible meanings Kinmen is endowed with in the context of the worldwide flow of goods and regionalization. A materiality and cultural discourse analysis approach will be adopted in this study, which aims to illustrate what social relations were changed, shaped or appropriated when Kinmen Kaoliang Liquor crossed the political and cultural boundary that is the Taiwan Strait. This will enable an examination of the range of meanings embodied by Kinmen with relation to Kaoliang liquor as a commodity, one being a rigid representative of a former battlefield, and the other a producer of a local cultural specialty. The construction of this dual identity helped to smoothly re-integrate the traditional Chinese spirits industry and the capital market, however, it can also act as a form of protection, in differentiating between “us” and “others” in terms of commodity governance. Therefore, the concept of ‘nation’ or ‘frontier’ is based on the constant negotiation between national role and capital expansion.

碩士
中原大學
電機工程研究所
93
Abstract This paper emphasize on the design and making of the full bridge phase shift resonance system for driving CCFL (Cold Cathode Fluorescent Lamp) and offers an easy balancing circuit for multiple lamps. Principle of CCFL lighting, detail analysis and full bridge phase shift resonance inverter designing are all discussed. An example for driving 4 lamps CCFL with balance for each lamp is also included.

Il lavoro riguarda l'indagine di un sistema di raffreddamento per impingement per pale di turbina a gas in condizioni statiche e rotanti. L'analisi è stata svolta per via sperimentale, utilizzando una implementazione innovativa della tecnica transient con cristalli liquidi termocromatici, che ne permette l'utilizzo in condizioni rotanti. I risultati sperimentali sono stati supportati da una analisi numerica CFD. L'indagine ha permesso di apprezzare le forti interazioni che hanno luogo tra la rotazione e i vari componenti del sistema, oltre che di verificare gli effetti di diverse condizioni di alimentazione e di estrazione dei getti di impingement per varie geometrie di raffreddamento. In this work, a leading edge cooling system for gas turbine blades has been investigated in static and rotating conditions. To achieve this goal, an experimental investigation has been carried out: a novel implementation of transient technique using thermochromic liquid crystals has been developed, which allows its application in rotating conditions. The experimental results have been supported by the outcomes of a numerical CFD analysis. The investigation revealed the strong interactions occurring between rotation and the different features of the system. Moreover, different supply and extraction conditions have been analyzed for various impingement geometries.

The objective of the present thesis, which lies within a national research project, is the analysis of a "cold bridge" leading edge cooling system for a high pressure gas turbine blade, with the aim to study the combined effects of jet impingement and mass flow extraction on heat transfer phenomena. Both experimental and numerical investigations have been carried out, with the main aim to assess the effects of rotation on the heat transfer distribution in a realistic leading edge internal cooling system. Experiments were performed in static and rotating conditions replicating the typical realistic range of jet Reynolds number (Rej) and Rotation number (Roj) up to 0.05 for three cross-flow cases representative of the working condition that can be found at blade tip, midspan and hub, respectively (CR of 10%, 40% and 70%). Experimental results show a significant dependency of Nusselt number value on Reynolds jet number which does not appreciably affect its distribution on the LE. On the contrary a mild relation has been found with respect to cross-flow conditions, which does not remarkably affect the averaged Nu value but sensibly impact on its pattern. Concerning rotating conditions, the aero-thermal field turned out to be rather complex, but a good agreement between heat transfer coeffcient and flow field measurement has been found. In particular, jet bending due to rotation strongly depends on cross-flow intensity, while Ro has a weak effect on both jet velocity core and area-averaged Nusselt number. A parallel computational analysis of the rig has also been performed, aimed at identifying a suitable numerical model to investigate such phenomenon in order to deepen its physical comprehension. Stationary tests with uniform extraction conditions have been simulated on a symmetric model by means of both a RANS approach (using a k-w SST turbulence model) and two hybrid RANS-LES models: Scale Adaptive Simulation (SAS) and Detached Eddy Simulation (DES). RANS, but also SAS and DDES approaches, present a slightly underestimation of heat transfer experimental values, but the heat exchange distribution shape is accurately reproduced by the models such as the HTC distributions and values trend with the investigated parameters. DDES has been exploited for the numerical investigation in rotating conditions. A fairly good agreement with experimental measurements is observed, which represent a further validation of the adopted computational model.

碩士
國立臺北教育大學
自然科學教育學系碩士班
98
This study was to explore the effectiveness of a project-based teaching strategy on students’ learning motivation, attitude and ability levels towards scientific inquiry. The researcher, a teacher in Miaoli, Taiwan taught a sixth grade class of 13 boys and 11 girls in primary school. The teacher implemented the project-based learning course with a socio-scientific driven question, “Could the Hou-Fong bridge not collapse?” for 12-week. The project consisted of two parts, (1)courses for the improvement of students’ inquiry ability, and (2)doing scientific inquiring project activities. Both parts were complementary during the instruction. The study, through mixed-method, collected data comprising (1)quantitative instruments including the stages of learning motivation, attitude and ability towards science inquiry which were used for pretest and posttest to examine the inquiry elevated by t-test and (2)qualitative data including video recording of the instruction, interviews, teacher self-report, and the final projects made by students. The results showed that: (1) The building of scaffoldings before and during the instruction helped increase the students’ understanding of scientific inquiry, (2) Students’ learning motivation and attitude were enhanced through practices, (3)This instruction not only cultivated the inquiry ability of project-based activities for the students, but also made the teacher to better understand how to use the scaffoldings as inquiry instruction. The study inspired the module to construct scaffolding project-based instruction for science educators.

Tese de doutoramento em Altos Estudos Contemporâneos, na especialidade de Ciência Política (História Política e Estudos Internacionais), apresentada à Faculdade de Economia da Universidade de Coimbra
A presente investigação analisa e compara material publicado por dois jornais, – Folha de São Paulo, do Brasil, e Público, de Portugal -, sobre referendos realizados nos dois países, respectivamente, em 2005 e 2007. O objetivo é verificar se nesse material há falas com argumentos que possam ser considerados úteis para contribuir com um processo deliberativo, na perspectiva da democracia defendida por Jürgen Habermas. Ancorado numa sugestão de Simone Chambers, o material jornalístico é classificado como retórica plebiscitária ou retórica deliberativa. A retórica plebiscitária se caracteriza pela presença de mais elementos que não contribuem para a realização de uma deliberação pública, enquanto a deliberativa contém significativa presença de subsídios considerados importantes para o desenvolvimento desse processo. O reforço de alguns elementos no material jornalístico, – e a investigação avalia e quantifica quais elementos a mídia privilegia -, pode fazer com que se aproxime ou se distancie daquilo que é qualificado como importante para um debate público numa perspectiva habermasiana. A decisão de acionar mais um ou outro elemento está entre as opções que a mídia faz. Ao optar, ela sai de uma zona de fronteira, com várias possibilidades em aberto, e realiza um processo de demarcação. E, ao demarcar, ela estabelece limites, seja para um ou para outro processo. Considerando que a mídia tem potenciais ambivalentes, a investigação assume este pressuposto: não é possível definir a priori o papel que a mídia desempenha em eventos específicos de deliberação pública, como no caso dos referendos, isto porque em seu material comparecem todos os elementos da retórica, tanto os tendentes a favorecer como aqueles que prejudicam um processo deliberativo. Mas dada sua lógica de produção e divulgação, ela revela alguns dos seus limites que a impedem de complexificar os temas da agenda pública. E a hipótese que se assume nesta tese é que as escolhas da mídia privilegiam mais os elementos da retórica que se coadunam com a lógica da evidência, que é refratária a um processo argumentativo. Por acionar em maior número os elementos que são limitadores de um processo argumentativo, é temerário apontar a mídia como fórum central para a deliberação pública. E, se o seu poder de abrangência pode ser tomado como potencialmente útil para a realização de processos deliberativos nas democracias contemporâneas, a simples disponibilidade desse dispositivo não permite chegar à conclusão açodada de que sua prática contribua efetivamente para o desenvolvimento do debate público. Pelo seu potencial, e por permitir que em seu interior também circule material identificado como uma retórica deliberativa, até pode-se ver na mídia um ator capacitado a realizar um papel complementar, mas não central, no processo mais amplo da deliberação pública. E, nessa linha de análise, não se pode descartar por completo a possibilidade de o material produzido pela mídia ser desencadeador de um processo deliberativo na sociedade ao ser apropriado ou reinterpretado de diferentes maneiras pelos diversos atores da esfera pública.