Este trabalho apresenta um estudo experimental acerca da influência da razão de espaçamento e da intensidade de turbulência no escoamento biestável. É estudado o escoamento sobre dois cilindros dispostos lado a lado, para o canal aerodinâmico com intensidade de turbulência inferior a 1%, para o canal aerodinâmico com grade promotora de turbulência com intensidade de turbulência de 8 a 7%, e para uma seção do canal aerodinâmico sem paredes laterais. A técnica experimental aplicada consiste na medição das flutuações de velocidade no canal aerodinâmico utilizando a técnica da anemometria de fio quente. As medições são realizadas com duas sondas, uma fixa e outra móvel que foi posicionada em seis pontos diferentes do escoamento. Os dados medidos são tratados através de ferramentas estatísticas, análise espectral e transformadas de ondaletas. Os resultados confirmam a existência do fenômeno da biestabilidade e mostram como o fenômeno sofre alterações quando exposto às condições de maior intensidade de turbulência e redução da razão de bloqueio pela retirada das paredes laterais em uma seção do canal. Para a condição de maior intensidade de turbulência, os resultados mostram que as trocas de modo se intensificam, e em alguns dos pontos de medição os sinais referentes à sonda móvel não apresentam características de biestabilidade. Para o caso sem paredes laterais, os sinais apresentam características de biestabilidade até o momento em que as paredes são removidas. / This work presents an experimental study, about the influence of the pitch to diameter ratio and the turbulence intensity on a bistable flow. The flow through two cylinders side-by-side is studied in an aerodynamic channel with turbulence intensity lower than 1%, in an aerodynamic channel with a turbulence grid, that increased the turbulence intensity to about 8 to 7%, and a section of the aerodynamic channel without lateral walls. The experimental technique consists in the measurements of the fluctuating velocities in the aerodynamic channel, using hot wire anemometry. The measurements are performed with two probes, one static, and one movable, positioned in six different points of the flow. The acquired data are analysed through statistical, spectral and wavelet tools. The results confirmed the occurrence of the bistable phenomenon and shows how it behaves when exposed to different conditions of turbulence intensity, and reduction of the blockage ratio aspect due to removal of the lateral walls of a channel section. The results for the higher turbulence intensity condition shows that the switches are intensified, some data resulting of the measurements of the second probe, do not show bistable characteristics. In the no-walls section case, the signals showed bistable features, until the moment the walls were removed.

Este trabalho apresenta o estudo multidisciplinar de uma micromáquina a vapor concebida para a utilização em sistemas de geração distribuída. O foco da pesquisa é o desenvolvimento do modelo matemático da micromáquina, que requereu conhecimentos da termodinâmica e suas leis, e a aplicação de conceitos de dinâmica, vibrações e controle, entre outros. Para a validação experimental do modelo foi reconstruída uma micromáquina já existente; também foi realizado o projeto da bancada, a seleção da instrumentação e a sua calibração. O estudo apresenta ainda a comparação entre os resultados teóricos e experimentais, bem como a sua análise e interpretação. / A multidisciplinary study of a micro steam engine conceived for distributed generation systems is presented. The research focuses on the development of the mathematical model of the micro engine, which required the knowledge of Thermodynamics and its laws, and concepts of dynamics, vibration and control, among others. In order to experimentally validate the model, a previous micro engine was redesigned and rebuilt; likewise, a new bench was designed, together with the selection and calibration of the measurement systems. The study also presents the comparison between experimental and theoretical results, as well as their analysis and discussion.

Compressed air is widely used particularly in industry. In order to increase the quality of the process and lifetime of the machine, the compressed air should be dried. Therefore the air is used after compression and drying processes. The most commonly used machines that do this process are called &ldquo / Refrigerant Air Dryers&rdquo / . These air dryers are designed to cool and dehumidify the moist air. The process of decreasing temperature is carried out by a refrigerant, R134a. Unlike design conditions, dryers are working in variable loads (variable compressed air flow rates). An experimental setup is prepared for analyzing the variance on the machine and the performance under these variable loads. This thesis includes the design, preparation and the modification of the refrigeration experimental setup for refrigerant air dryers. The setup is tested under three different conditions and the results are compared.

This thesis investigates the refrigerant (R-134a) flow in a minitube experimentally. The small scale heat transfer is a relatively new research area and has been in favor since the end of 1970&rsquo / s. Refrigerant flow in mini- and microscale media is a potential enhancement factor for refrigeration technology in the future. For the forthcoming developments and progresses, experimental studies are invaluable in terms of having an insight and contributing to the establishment of infrastructure in the field in addition to leading the numerical and theoretical approaches. The studies in the literature show that low mass flow rate and constant wall temperature approach in minitubes and minichannels were not among the main areas of interest. Therefore, an experimental set-up was prepared in order to perform experiments of two-phase refrigerant flow in a 1.65 mm diameter copper minitube with the constant wall temperature approach. The design, preparation, and modifications of the experimental set-up are explained in this thesis. Two-phase flow and quality arrangements were done by pre-heating the refrigerant at saturation pressure and the constant wall temperature was achieved by a secondary cycle with water and ethylene glycol mixture as the working fluid. The heat transfer coefficient and the pressure drop for the two-phase flow with varying quality values and saturation temperatures of the refrigerant were calculated and compared with the results available in literature.

The gaseous species concentration of Jet A-1, GTL, CTL and a blend of 80 vol.% GTL and 20 vol.% hexanol jet fuels in laminar coflow diffusion flames have been measured and studied. These species are carbon monoxide, carbon dioxide, oxygen, methane, ethane, ethylene, propylene, and acetylene. Benzene and propyne concentrations were also detected in CTL flames. 1-Butene has been quantified for the blend of GTL and hexanol flame. The detailed experimental setup has been described and results from different flames are compared. The CO is produced in a same amount in all the flames. The CTL flame had the largest and GTL/hexanol flame had lowest CO2 concentrations. The results indicate that GTL and GTL hexanol blend flames produce similar concentrations for all the measured hydrocarbon species and have the highest concentration among all the jet fuels. The experimental results from Jet A-1 fuel are also compared with numerical studies by Saffaripour et al.

With the increasing demand on multimedia applications over the Internet, and the growing number of mobile smart devices people are using, it is helpful to develop a mobile network architecture that can support multimedia transmission without using infrastructures. We propose that service overlay networks over MANETs can serve as a supplement to the existing 3G/4G networks and Wi-Fi access point networks. In this thesis we present experiment results that show the feasibility of mobile service overlay networks to meet the requirements of multimedia streaming. And also, we improved one of the existing overlay protocols. The improved protocol takes physical location into consideration when establishing connections in the overlay network. It also limits the number of neighbors each node can have, which prevents a particular node from becoming the bottleneck of the network, when connected to too many neighbors. Evaluation results show the new protocol reduces network packet loss rate.

The gaseous species concentration of Jet A-1, GTL, CTL and a blend of 80 vol.% GTL and 20 vol.% hexanol jet fuels in laminar coflow diffusion flames have been measured and studied. These species are carbon monoxide, carbon dioxide, oxygen, methane, ethane, ethylene, propylene, and acetylene. Benzene and propyne concentrations were also detected in CTL flames. 1-Butene has been quantified for the blend of GTL and hexanol flame. The detailed experimental setup has been described and results from different flames are compared. The CO is produced in a same amount in all the flames. The CTL flame had the largest and GTL/hexanol flame had lowest CO2 concentrations. The results indicate that GTL and GTL hexanol blend flames produce similar concentrations for all the measured hydrocarbon species and have the highest concentration among all the jet fuels. The experimental results from Jet A-1 fuel are also compared with numerical studies by Saffaripour et al.

With the increasing demand on multimedia applications over the Internet, and the growing number of mobile smart devices people are using, it is helpful to develop a mobile network architecture that can support multimedia transmission without using infrastructures. We propose that service overlay networks over MANETs can serve as a supplement to the existing 3G/4G networks and Wi-Fi access point networks. In this thesis we present experiment results that show the feasibility of mobile service overlay networks to meet the requirements of multimedia streaming. And also, we improved one of the existing overlay protocols. The improved protocol takes physical location into consideration when establishing connections in the overlay network. It also limits the number of neighbors each node can have, which prevents a particular node from becoming the bottleneck of the network, when connected to too many neighbors. Evaluation results show the new protocol reduces network packet loss rate.

This thesis presents the results of an experimental study designed to examine whether children raised bilingually in Japanese and English from birth in Christchurch, New Zealand, exhibit the same morphological case and topic marking knowledge in Japanese as monolingual children in Japan. The participants were 34 children aged between five and eleven years who have been raised in a one-person one-language environment in an English dominant community. The study replicated previous studies on monolingual Japanese children, and involved two widely used paradigms for assessing a child’s grammar: picture selection, and elicited imitation. The responses of the children in this study were different from those reported in studies of monolingual children. In the picture selection tasks, some children in this study interpreted the agent-patient relationship based on the word order cue in the object-initial types of transitive sentences, whereas previous studies have demonstrated that monolingual children five years and older are able to interpret the agent-patient relationship in the same way as adults, using the case marking cue. Moreover, in the elicited imitation tasks, many children in this study re-analysed the topic-comment construction as a genitive possessive when the particles in the stimuli were masked with noise. This pattern has not been reported in any previous study. The results also revealed that there was a great degree of individual variation. The study suggests cross-linguistic influence from English on Japanese as a possible explanation for the difference between the children in this study and monolinguals. The phenomena observed in the results satisfies two conditions for cross-linguistic influence proposed by Hulk and Müller (2000) and Müller and Hulk (2001), because (i) English and Japanese overlap at the surface level in terms of the agent position in a canonical sentence and the possessive structure, and (ii) the problematic structures for some children in this study involved the interface between syntax and pragmatics in the C-domain. The study, however, has no principled explanation for the individual variation found because of a lack of data on the Japanese input and the child’s fluency, both of which are likely to affect simultaneous bilingual development.

The present research is conducted to investigate the behaviour of elliptical tube columns filled with self-compacting concrete (SCC). In total, ten specimens, including two empty columns, were tested to failure. The main parameters investigated were the length and the sections of the columns, and the concrete compressive strength. Artificial Neural Network (ANN) model was developed to predict the compressive strength of SCC using a comprehensive database collected from different previous studies. The database was used to train and test the developed ANN. Moreover, parallel to the experimental works, a three dimensional nonlinear finite element (FE) model using ABAQUS software was developed to predict the behaviour of SCC elliptical tube columns. The proposed ABAQUS model was verified against the current experimental results. The experimental results indicated that the failure modes of the SCC filled elliptical steel tube columns having large slenderness ratios were dominated by global buckling. Moreover, the composite columns possessed higher critical axial compressive capacities compared with their hollow section companions due to the composite interaction. However, due to the large slenderness ratio of the test specimens, the change of compressive strength of concrete core did not show significant effect on the critical axial compressive capacity of concrete filled columns although the axial compressive capacity increased with the concrete grade increase. The comparisons between the axial compressive load capacities obtained from experimental study and those predicted using simple methods provided in Eurocode 4 for concrete-filled steel rectangular tube columns showed a reasonable agreement. The proposed three dimensional FE model accurately predicted the failure modes, the load capacity and the load-deflection response of the columns tested. The experimental results, analysis and comparisons presented in this thesis clearly support the application of self-compacting concrete filled elliptical steel tube columns in construction engineering practice.