Tonal noise propagating in ducts and radiating from their outlets is a common problem in situations where a fan or a blower is used to drive exhaust gases through the exhaust duct out to the environment. It is also a problem in the exhausts of large diesel engines such as those used to power large marine vessels. One way of attenuating tonal noise propagating in ducts is to use one or more side branch resonators, each of which is specifically designed for optimal performance at a particular frequency. One of the major problems associated with the use of side branch resonators is that any slight change in excitation frequency decreases the effectiveness of the resonators. The change in excitation frequency can be caused by a change in the speed of the engine, fan or blower, or change in temperature in the duct, which changes the speed of sound, and hence the wavelength of the noise. Resonators incorporating a provision for altering their geometry in real - time in order to adapt to environmental or operating condition changes is one approach that has been used by previous researchers. In particular, adaptive Helmholtz resonators have received considerable attention in the literature. Previous work has involved the use of one or more pressure sensors located in the duct downstream of the resonator to provide a cost function to be minimised by an electronic control system which alters the geometry of the resonator. However, in many cases, especially where the duct serves as a passage for exhaust gases to be driven out to the environment, it is not desirable to mount microphones in the duct. Also, microphones located remote from the resonator introduce wiring problems as well as the need to mount the microphones at the correct location in the duct, which will change as the wavelength of the tonal noise in the duct changes as a result of changes in operating or environmental conditions. It is highly desirable to have a completely self - contained Helmholtz resonator ( HR ) which can be attached to the duct and for which the only external wiring needed is the power supply. The work described in this thesis is concerned with the development of a self - contained adaptive HR which can be optimally tuned by using signals from two microphones located in the cavity and neck of the resonator, respectively. The primary focus of the work is the development of a novel cost function, which can be used by an electronic controller to optimally tune the HR. The scope of the analysis has been restricted here to the ' no mean flow ' condition. The theoretical and numerical analysis of the duct - HR system is first conducted using the well known transfer matrix method and finite element analysis ( FEA ) software package ANSYS, respectively. The net acoustic power transmission in the duct downstream of the HR is estimated by using the two - microphone method. Analysing the duct - HR system with the transfer matrix method mandates the incorporation of three end - correction factors which are related to the unflanged open end of the duct, neck - cavity interface and neck - duct interface. However, because of the complexity in estimating the end - correction factor of the neck at the neck - duct interface due to the generation of a complex sound field in the vicinity of the neck opening, the transfer matrix method only approximates the in - duct net acoustic power transmission. This implies that changing the value of the neck - duct interface end - correction factor changes the calculated frequency at which the maximum reduction of in - duct net acoustic power transmission downstream of the HR occurs. On the other hand, ANSYS does not require the inclusion of any kind of end - correction factors apart from the actual physical dimensions of the system, and is thus much more accurate than the transfer matrix method. To minimise the in - duct net acoustic power transmission downstream of the HR, a number of different cost functions that were related to the net acoustic power transmission were investigated theoretically, numerically and experimentally. These all involved either the acoustic pressure at the top of the closed end of the cavity of the HR or at the neck wall of the HR close to the neck - duct interface or the amplitude of the pressure transfer function between two microphones located in the resonator. The two potential cost functions which were initially considered to be maximised for indicating the minimisation of the in - duct net acoustic power transmission downstream of the resonator were : ( a ) the pressure at the top of the closed end of the cavity, and ( b ) the amplitude of the pressure transfer function between the pressure at the top of the closed end of the cavity and the pressure at the neck wall close to the neck - duct interface. It was found that the location of the microphone in the neck was extremely important, with the best location being at the centre of the duct adjacent to the neck opening. However, this location was not considered practical because a microphone in the duct can obstruct the mean flow of gas in the duct. The best location for mounting the microphone in the neck was found to be at the neck wall as close as possible to the neck - duct interface. The results are shown in two different ways : ( 1 ) broadband analysis, whereby the in - duct net acoustic power transmission downstream of the HR, the pressure at the top of the closed end of the cavity and the pressure transfer function between the pressure at the top of the closed end of the cavity and at the neck wall close to the neckduct interface are plotted as a function of frequency, and ( 2 ) single frequency analysis, whereby all the aforementioned results are plotted as a function of the cylindrical cavity length ( for a fixed cavity diameter ) for a single, tonal frequency. For broadband analysis, the numerical ( ANSYS ) results showed that the frequency at which the maximum reduction of in - duct net acoustic power transmission downstream of the HR occurs differs from the frequencies which correspond to the maximum responses of cost functions ( a ) and ( b ) described above. For single frequency analysis, when trying to optimise the performance of a duct - mounted HR at a particular frequency by altering its volume, the optimal dimensions of the HR required to attain the maximum reduction of in - duct net acoustic power transmission at that frequency differ from the dimensions of the HR which correspond to the maximised responses of the cost functions ( a ) and ( b ). These results were validated experimentally using a 3 m long circular duct of 0.1555 m diameter with an attached cylindrical HR. During the experimental work, only plane waves were propagating down the duct and there was no mean flow in the duct. Instead of only focusing on the amplitude of the pressure transfer function between the pressures at the top of the closed end of the cavity and the pressure at the neck wall close to the neck - duct interface, the phase difference between the same locations in the HR was also considered. It was found that the phase difference depends on the quality factor ( or damping ) of the entire acoustic system. Experiments were conducted with varying dimensions of the HR and two novel cost functions were empirically derived. Both cost functions, which does not include any kind of measurement remote from the HR, are based on the damping ( or the quality factor ) of the duct - HR system and the phase difference between the pressure at the top of the closed end of the cavity and the pressure at the neck wall close to the neck - duct interface. The effectiveness and performance of both cost functions were found to be excellent for minimising the in - duct net acoustic power transmission downstream of the HR. However, the second cost function is preferred because the procedure involved for measuring the system damping is more convenient from the practical point of view than the procedure for the first one. The quality factor of the duct - mounted HR, at the frequency at which noise needs to be attenuated, was determined by tuning the length of the cavity of the HR so as to maximise the amplitude of the pressure transfer function of the HR. This estimated quality factor was found to be directly related to the transfer function phase which corresponds to the minimum in - duct net acoustic power transmission at the tonal frequency. Once this optimum transfer function phase is known, an active control system can be used to drive a motor to adjust the cavity length of the HR to achieve the optimum phase. / Thesis (M.Eng.Sc.)--School of Mechanical Engineering, 2006.

No description available.

A theoretical model was developed to predict the air distribution pattern and thus to design perforated ventilation ducts equipped with a fan. The analysis of the air distribution pattern of such systems requires accurate measurement procedures. Several experimental methods were tested and compared. Accordingly, the piezometric flush taps and thermo-anemometer were selected to measure respectively the duct air pressure and the outlet air flow. / Based on the equations of energy and momentum conservation, a model was formulated to predict the air flow performance of perforated ventilation ducts and to evaluate the outlet discharge angle and the duct regain coefficients without evaluating frictional losses. The basic assumptions of the model were validated by experimentally proving the equivalence of the friction losses expressed in the 2 cited equations. When compared to experimental results measured from four wooden perforated ventilation ducts with aperture ratios of 0.5, 1.0, 1.5, and 2.0, the model predicted the outlet air flow along the full length of perforated duct operated under turbulent flow conditions with a maximum error of 9%. The regain coefficient and the energy correction factor were equal to one, and the value of the discharge coefficient remained constant at 0.65, along the full length of the perforated duct. The outlet air jet discharge angle varied along the entire duct length, and was not influenced by friction losses for turbulent flow. / Assuming a common effective outlet area, the model was extended to match the performance of the fan and the perforated duct and to determine their balance operating point.

Discharge coefficients are an important parameter in the prediction of the air displacement performance of ventilation outlets and in the design of ventilation ducts. / Discharge coefficients of a wooden ventilation duct 8.54 metres in length and of a constant 0.17 m$ sp2$ cross sectional area were measured. Four different outlet shapes and 3 aperture ratios of each shape were tested. A split plot experimental design was used to evaluate the effect of outlet shape, outlet size, and distance from the fan on discharge coefficient. The relationship between duct performance characteristics and discharge coefficient was examined. A mathematical equation to predict the discharge coefficient was developed and tested. / Discharge coefficient values measured ranged from 0.19 to 1.25 depending on the aperture ratio and distance from the fan. Outlet shape had no significant effect. The apparent effects of aperture ratio and size are due to the effects of head ratio. The equation predicting the discharge coefficient had a maximum error of 5 percent for the aperture ratios of 0.5 and 1.0, and 15 percent at an aperture ratio of 1.5.

Thesis (M.Eng.Sc.) -- University of Adelaide, School of Mechanical Engineering, 2007. / Includes author's previously published papers. "Dissertation submitted for the award of the degree of Master of Engineering Science on the 25th of September, 2006. Qualified on the 28th November, 2006" Includes bibliography (p. 191-199) Also available in print form.

Made available in DSpace on 2014-10-09T12:44:05Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:20Z (GMT). No. of bitstreams: 1 06891.pdf: 3372488 bytes, checksum: 65b8800e6379779a3f9693d8cbc1c688 (MD5) / Dissertacao [Mestrado] / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares, Sao Paulo

Made available in DSpace on 2014-10-09T12:44:05Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:20Z (GMT). No. of bitstreams: 1 06891.pdf: 3372488 bytes, checksum: 65b8800e6379779a3f9693d8cbc1c688 (MD5) / Dissertacao [Mestrado] / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares, Sao Paulo

Orientador: Rosely Palermo Brenelli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação / Made available in DSpace on 2018-08-23T22:28:23Z (GMT). No. of bitstreams: 1 Dalfre_AnaPauladeProspero_M.pdf: 2856845 bytes, checksum: a650aa916172be7554b024f181ccd04c (MD5) Previous issue date: 2013 / Resumo: Fundamentada na Epistemologia e Psicologia Genéticas de Jean Piaget, a presente pesquisa teve por objetivos: caracterizar as condutas de jogo em escolares do 5º, 7º e 9º anos do Ensino Fundamental; analisar os erros cometidos pelos escolares; identificar os níveis de abstração reflexiva e relacionar os níveis de abstração reflexiva às condutas de jogo. Participaram do estudo trinta escolares da rede pública de ensino, respectivamente 10 alunos do 5º, 7º e 9º anos do Ensino Fundamental. A seleção dos participantes foi aleatória e obtida por meio de sorteio. O procedimento para a coleta dos dados contou com quatro encontros individuais em que foram utilizados a Prova de Abstrações a partir de Ações de Deslocamentos e de suas Coordenações e o jogo Hora do Rush. Os dados foram analisados qualitativa e quantitativamente. Ao considerar o êxito na solução das cartas-desafio com o número mínimo de deslocamentos, foram encontradas diferenças significativas entre a proporção dos mesmos nas dez cartas. Com relação às condutas de jogo, encontramos quatro níveis de conduta (I, IIA, IIB e III) sendo que a maior parte dos nossos escolares apresentou o nível II de conduta. Quanto aos erros, encontramos sete tipos deles entre os nossos participantes e, mais especificamente, três deles foram estatisticamente mais expressivos. Ao relacionarmos os erros e as condutas de jogo, verificamos que condutas de jogo mais evoluídas estão diretamente relacionadas ao menor número de erros cometidos. O teste de comparações múltiplas de Tukey indicou que a média de erros foi significativamente superior para o nível de conduta de jogo IIA, assim como os participantes do 5º ano cometeram mais erros quando comparados aos participantes do 9º ano de escolaridade. Ao caracterizarmos os níveis de abstração reflexiva, encontramos escolares em todos os quatro níveis descritos (I, IIA, IIB e III). Ao relacionar as condutas de jogo e os níveis de abstração reflexiva, quantitativamente não se configurou uma associação significativa (teste Qui-Quadrado), entretanto, o resultado do teste estatístico foi avaliado com cautela e, qualitativamente, observamos uma evolução que segue em paralelo e indica que conforme avança o nível de abstração reflexiva, avança também o nível de conduta de jogo. Esses dados nos permitiram inferir que para obter êxito com o número mínimo de deslocamentos nas cartas-desafio do jogo Hora do Rush há necessidade do raciocínio operatório. Quanto às implicações psicopedagógicas, este estudo pode se constituir em um recurso para conhecer "como" os sujeitos jogam Hora do Rush e como passam de um nível de conduta de jogo mais elementar para um nível mais evoluído. Além disso, os procedimentos utilizados para a coleta e análise dos dados podem servir de referencial para futuros estudos e para a prática das intervenções psicopedagógicas. / Abstract: Based on the Epistemology and Psychology Genetic Jean Piaget, the present study aimed to characterize the conduct of gaming in school the 5th, 7th and 9th grades of elementary school, analyze the mistakes made by the students, to identify the levels of reflective abstraction and relate reflective abstraction levels to conduct gaming. Participants were thirty students in the public schools, respectively 10 students in the 5th , 7th and 9th grades of elementary school. The selection of participants was obtained through random draw. The procedure for data collection featured four individual meetings that were used in the Proof of Abstractions from actions Displacements and their Coordinators and the game Rush Hour. The data were analyzed qualitatively and quantitatively. When considering the successful solution of the letters of challenge with the minimum number of shifts, significant differences were found between the proportion of the same ten cards. With respect to the conduct of gaming, we find four levels of conduct (I , IIA , IIB and III ) is that most of our students had the level II of conduct. The errors we found seven types of them among our participants and, more specifically, three of them were statistically more significant. Relating the errors and conduct the game, we found that game more evolved behaviors are directly related to fewer mistakes. The test of Tukey multiple comparisons indicated that the error rate was significantly higher for the level of gaming behavior IIA, as well as the participants of the 5th year made more errors when compared to participants in the 9th grade. To characterize the levels of reflective abstraction, found in all four school levels described (I , IIA , IIB and III ). Relate to the conduct of play and levels of reflective abstraction, quantitatively not configured a significant association ( chi-square test ), however, the statistical test results was evaluated with caution and qualitatively observe an evolution that follows in parallel and indicates that as the level progresses from reflexive abstraction , also advances the level of gaming behavior. These data allowed us to infer that in order to succeed with the minimum number of letters offsets the challenge of the game Rush Hour no need of reasoning surgery. The implications psycho, this study may constitute a resource to know "how" guys play Rush Hour and how to pass a level of gaming behavior most basic to a more evolved. Furthermore, the procedures used for the collection and analysis of data can serve as a benchmark for future studies and for the practice of psycho interventions. / Mestrado / Psicologia Educacional / Mestra em Educação

No description available.

(A) Gastric Secretion The present study was performed to investigate the canine post-pancreatic duct ligation GIP secretion in response to fat ingestion using a meat meal mixed with unhydrolyzed or hydrolyzed whipping cream, and to determine whether GIP plays a role in the production of hyperacid secretion in the pancreatic duct ligated dogs. Four mongrel female dogs were prepared with Heidenhain pouch (HP) and gastric fistula (GF), and daily acid secretion from the HP was measured before and after pancreatic duct ligation (PDL). HP acid output, serum immunoreactive gastrin (IR-Ga) and serum immunoreactive gastric inhibitory polypeptide (IR-GIP) concentrations during five hours following oral ingestion of a meat meal alone, a meat meal mixed with 125g of unhydrolyzed cream and meat meal mixed with 125g of hydrolyzed cream were measured before and after PDL. Twenty four hour HP acid outputs increased significantly in each of the four dogs after PDL. Five hour HP acid outputs in response to a meat meal alone and a meat meal plus unhydrolyzed cream were modestly increased, while those in response to a meat meal plus hydrolyzed cream were rather reduced after PDL. Serum IR-Ga responses to all stimulants were lowered after PDL and those to meat meal plus hydrolyzed cream lowered most markedly. Serum IR-GIP responses to a meat meal alone were significantly increased, while those to a meat meal plus unhydrolyzed and hydrolyzed cream were reduced. The results of the present study demonstrate serum IR-GIP in response to a meat meal is increased by PDL in dogs, suggesting augmented acid juice passing into the intestinal lumen is responsible for the increased GIP response. It is indicated that hypo-secretion of GIP is not the cause of hypersecretion of gastric acid in the PDL dogs. (B) Glucose Metabolism. Functional alteration in glucose homeostasis especially concerning the early onset of diabetes after PDL was studied in dogs. Intravenous (i.v.) and intragastric glucose tolerance tests were performed at two to ten weeks and two weeks after PDL respectively. Serum glucose, IRI, and IR-GIP in response to a meat meal with and without unhydrolyzed or hydrolyzed fat were estimated at six weeks after PDL. Significantly impaired glucose tolerance and early phase IRI secretion after i.v. glucose were shown at two to ten weeks after PDL. Intragastric glucose load revealed delayed pattern of serum glucose and IRI (no evidence of glucose intolerance or diminished IRI secretion), indicating decreased gastric motility after PDL. Serum IR-GIP response to intragastric glucose load was not attenuated by the operation but showed a similar pattern to IRI response. Serum IRI responses to meat meals with and without unhydrolyzed or hydrolyzed cream were impaired after PDL. It is indicated that dogs after PDL show early onset (two to ten weeks) of diabetes, i.e. blunted early phase insulin secretion, 2 the mechanism of GIP secretion as an insulinotropic enterohormone remains intact after PDL if sufficient stimulants are given. / Surgery, Department of / Medicine, Faculty of / Graduate