An Acoustic Analysis of Valveless Pulsejet Engines

Valveless pulsejets are extremely simple aircraft engines; essentially cleverly designed tubes with no moving parts. These engines utilize pressure waves, instead of machinery, for thrust generation, and have demonstrated thrust-to-weight ratios over 8 and thrust specific fuel consumption levels below 1 lbm/lbf-hr – performance levels that can rival many gas turbines. Despite their simplicity and competitive performance, they have not seen widespread application due to extremely high noise and vibration levels, which have persisted as an unresolved challenge primarily due to a lack of fundamental insight into the operation of these engines. This thesis develops two theories for pulsejet operation (both based on electro-acoustic analogies) that predict measurements better than any previous theory reported in the literature, and then uses them to devise and experimentally validate effective noise reduction strategies. The first theory analyzes valveless pulsejets as acoustic ducts with axially varying area and temperature. An electro-acoustic analogy is used to calculate longitudinal mode frequencies and shapes for prescribed area and temperature distributions inside an engine. Predicted operating frequencies match experimental values to within 6% with the use of appropriate end corrections. Mode shapes are predicted and used to develop strategies for suppressing higher modes that are responsible for much of the perceived noise. These strategies are verified experimentally and via comparison to existing models/data for valveless pulsejets in the literature. The second theory analyzes valveless pulsejets as acoustic systems/circuits in which each engine component is represented by an acoustic impedance. These are assembled to form an equivalent circuit for the engine that is solved to find the frequency response. The theory is used to predict the behavior of two interacting pulsejet engines. It is validated via comparison to experiment and data in the literature. The technique is then used to develop and experimentally verify a method for operating two engines in anti-phase without interfering with thrust production. Finally, Helmholtz resonators are used to suppress higher order modes that inhibit noise suppression via anti-phasing. Experiments show that the acoustic output of two resonator-equipped pulsejets operating in anti-phase is 9 dBA less than the acoustic output of a single pulsejet.

Cholangiocarcinoma: from molecular biology to treatment

Cholangiocarcinoma is a rare tumor originating in the bile ducts, which, according to their anatomical location, is classified as intrahepatic, extrahepatic and hilar. Nevertheless, incidence rates have increased markedly in recent decades. With respect to tumor biology, several genetic alterations correlated with resistance to chemotherapy and radiotherapy have been identified. Here, we highlight changes in KRAS and TP53 genes that are normally associated with a more aggressive phenotype. Also IL-6 and some proteins of the BCL-2 family appear to be involved in the resistance that the cholangiocarcinoma presents toward conventional therapies. With regard to diagnosis, tumor markers most commonly used are CEA and CA 19-9, and although its use isolated appears controversial, their combined value has been increasingly advocated. In imaging terms, various methods are needed, such as abdominal ultrasound, computed tomography and cholangiopancreatography. Regarding therapy, surgical modalities are the only ones that offer chance of cure; however, due to late diagnosis, most patients cannot take advantage of them. Thus, the majority of patients are directed to other therapeutic modalities like chemotherapy, which, in this context, assumes a purely palliative role. Thus, it becomes urgent to investigate new therapeutic options for this highly aggressive type of tumor.

A New Mouse Model That Spontaneously Develops Chronic Liver Inflammation and Fibrosis

Here we characterize a new animal model that spontaneously develops chronic inflammation and fibrosis in multiple organs, the non-obese diabetic inflammation and fibrosis (N-IF) mouse. In the liver, the N-IF mouse displays inflammation and fibrosis particularly evident around portal tracts and central veins and accompanied with evidence of abnormal intrahepatic bile ducts. The extensive cellular infiltration consists mainly of macrophages, granulocytes, particularly eosinophils, and mast cells. This inflammatory syndrome is mediated by a transgenic population of natural killer T cells (NKT) induced in an immunodeficient NOD genetic background. The disease is transferrable to immunodeficient recipients, while polyclonal T cells from unaffected syngeneic donors can inhibit the disease phenotype. Because of the fibrotic component, early on-set, spontaneous nature and reproducibility, this novel mouse model provides a unique tool to gain further insight into the underlying mechanisms mediating transformation of chronic inflammation into fibrosis and to evaluate intervention protocols for treating conditions of fibrotic disorders.

Evaluation Of An Extended Duct Air Delivery System For Spaces Conditioned By Rooftop Units

Traditional air delivery to high-bay buildings involves ceiling level supply and return ducts that create an almost-uniform temperature in the space. Problems with this system include potential recirculation of supply air and higher-than-necessary return air temperatures. A new air delivery strategy was investigated that involves changing the height of conventional supply and return ducts to have control over thermal stratification in the space. A full-scale experiment using ten vertical temperature profiles was conducted in a manufacturing facility over one year. The experimental data was utilized to validated CFD and EnergyPlus models. CFD simulation results show that supplying air directly to the occupied zone increases stratification while holding thermal comfort constant during the cooling operation. The building energy simulation identified how return air temperature offset, set point offset, and stratification influence the building’s energy consumption. A utility bill analysis for cooling shows 28.8% HVAC energy savings while the building energy simulation shows 19.3 – 37.4% HVAC energy savings.

Studies of turbulent flows in continuous casting of steel with and without magnetic field

This thesis develops and tests various transient and steady-state computational models such as direct numerical simulation (DNS), large eddy simulation (LES), filtered unsteady Reynolds-averaged Navier-Stokes (URANS) and steady Reynolds-averaged Navier-Stokes (RANS) with and without magnetic field to investigate turbulent flows in canonical as well as in the nozzle and mold geometries of the continuous casting process. The direct numerical simulations are first performed in channel, square and 2:1 aspect rectangular ducts to investigate the effect of magnetic field on turbulent flows. The rectangular duct is a more practical geometry for continuous casting nozzle and mold and has the option of applying magnetic field either perpendicular to broader side or shorter side. This work forms the part of a graphic processing unit (GPU) based CFD code (CU-FLOW) development for magnetohydrodynamic (MHD) turbulent flows. The DNS results revealed interesting effects of the magnetic field and its orientation on primary, secondary flows (instantaneous and mean), Reynolds stresses, turbulent kinetic energy (TKE) budgets, momentum budgets and frictional losses, besides providing DNS database for two-wall bounded square and rectangular duct MHD turbulent flows. Further, the low- and high-Reynolds number RANS models (k-ε and Reynolds stress models) are developed and tested with DNS databases for channel and square duct flows with and without magnetic field. The MHD sink terms in k- and ε-equations are implemented as proposed by Kenjereš and Hanjalić using a user defined function (UDF) in FLUENT. This work revealed varying accuracies of different RANS models at different levels. This work is useful for industry to understand the accuracies of these models, including continuous casting. After realizing the accuracy and computational cost of RANS models, the steady-state k-ε model is then combined with the particle image velocimetry (PIV) and impeller probe velocity measurements in a 1/3rd scale water model to study the flow quality coming out of the well- and mountain-bottom nozzles and the effect of stopper-rod misalignment on fluid flow. The mountain-bottom nozzle was found more prone to the longtime asymmetries and higher surface velocities. The left misalignment of stopper gave higher surface velocity on the right leading to significantly large number of vortices forming behind the nozzle on the left. Later, the transient and steady-state models such as LES, filtered URANS and steady RANS models are combined with ultrasonic Doppler velocimetry (UDV) measurements in a GaInSn model of typical continuous casting process. LES-CU-LOW is the fastest and the most accurate model owing to much finer mesh and a smaller timestep. This work provided a good understanding on the performance of these models. The behavior of instantaneous flows, Reynolds stresses and proper orthogonal decomposition (POD) analysis quantified the nozzle bottom swirl and its importance on the turbulent flow in the mold. Afterwards, the aforementioned work in GaInSn model is extended with electromagnetic braking (EMBr) to help optimize a ruler-type brake and its location for the continuous casting process. The magnetic field suppressed turbulence and promoted vortical structures with their axis aligned with the magnetic field suggesting tendency towards 2-d turbulence. The stronger magnetic field at the nozzle well and around the jet region created large scale and lower frequency flow behavior by suppressing nozzle bottom swirl and its front-back alternation. Based on this work, it is advised to avoid stronger magnetic field around jet and nozzle bottom to get more stable and less defect prone flow.

Dificuldades no aleitamento materno

Enquadramento: Apesar de o leite materno ser globalmente aceite como o alimento mais completo e efetivo para assegurar a saúde do bebé, além dos claros benefícios para a mãe, continua-se a verificar que a taxa de amamentação está ainda longe da pretendida. Objetivos: Identificar a evidência científica dos determinantes da interrupção do aleitamento materno aos 6 meses de vida do bebé. Métodos: Foi realizada uma revisão sistemática da literatura sobre as dificuldades que levam à interrupção do aleitamento materno aos 6 meses de vida do bebé. Efetuou-se uma pesquisa na PUBMED, The Cochrane Library, Scielo e Google Académic de estudos publicados entre janeiro de 2010 a outubro de 2015, partindo dos critérios de inclusão previamente definidos, os estudos selecionados foram posteriormente avaliados. Dois revisores avaliaram a qualidade dos estudos a incluir, utilizando a grelha para a avaliação crítica de um estudo. Após a avaliação crítica da qualidade, foram incluídos no corpus de estudo 4 artigos com scores entre 87.5% e 95.0%. Resultados: Como metasíntese e seleção da análise dos artigos, inferiu-se que os fatores que levam à interrupção do aleitamento materno aos 6 meses de vida do bebé são: as preocupações com a lactação, perda de peso do bebé, doença da mãe ou a necessidade de tomar medicação, bloqueio dos ductos mamários, problemas relacionados com a gestão psicossocial, conflitos no seu estilo de vida, o posicionamento e pega inadequados, queixa de leite insuficiente ou fraco, dor à amamentação, fissuras, ingurgitamento mamário, a ansiedade materna e o choro da criança. Conclusões: Perante a evidência científica, as causas de abandono do aleitamento materno são multifatoriais e estão associadas à mãe, ao bebé e à saúde. A promoção do aleitamento materno exige programas de educação baseados na evidência, contribuindo para melhoria dos índices nacionais de prevalência da amamentação até, pelo menos aos 6 meses de vida do bebé, que se deseja cada vez mais consentânea com as melhores práticas internacionais. Palavras-Chave: Aleitamento materno; Dificuldades; Interrupção.

Cable laying and pulling

The common methods of cable laying are: • Direct in the ground in trenches (underground cables). • In cable trenches in outdoors switchyards. • In cable trays or cable ducts • Fixed with clamps (usually at walls and ceilings). • In conduits.

Primary biliary cirrhosis: proposal for a new simple histological scoring system

International audience

Modelagem da propagação sonora em dutos : abordagem matemática no domínio da frequência e do tempo utilizando transformada de laplace

Dissertação (mestrado)—Universidade de Brasília, Faculdade UnB Gama, Faculdade de Tecnologia, Programa de Pós-graduação em Integridade de Materiais da Engenharia, 2016.

Energy Audit for an Old Industrial Building in Gävle

(English)The Swedish industrial sector has overcome the oil crisis and has maintained the energy use constant even though the production has grown. This has been achieved thanks to the development of several energy policies, by the Swedish government, towards the 2020 goals. This thesis carries on this path and performs an energy audit for an old industrial building in Gävle (Sweden) in order to propose different energy efficiency measures to use less energy while maintaining the thermal comfort. The building is in quite a bad shape and some of the areas are unused making them a waste of money. By means of the invoices provided by different companies, the information from the staff and some measures that have been carried out in-situ, the energy balance has been calculated from where conclusions have been drawn. Although it is an industrial building, the study is not going to be focused in the industrial process but in the building’s envelope and support processes, since the unit combines both production and office areas. Therefore, the energy balance is divided in energy supplies (district heating, free heating and sun irradiation) and energy losses (transmission, ventilation hot tap water and infiltrations). The results show that the most important supply is that of the DH whereas the most important losses are the transmission and infiltration. Thus, the measures proposed are focused on the reduction of this relevant parameters. The most important measures are the renovation of the windows, heating systems valves and the ventilation. The glazing of the dwelling is old and some of it is broken accounting for quite a large amount of the losses. The radiator valves are not properly working and there does not exist any temperature control. Therefore the installation of thermostatic valves turns out to be a must. Moreover, some part of the building has no mechanical ventilation but conserves the ducts. These could be utilized if they are connected to the workshop’s ventilation which is capable of generating sufficient flow for the entire building. Finally, although other measures could also be carried out, the ones proposed appear to be the essential ones. A further analysis should be carried out in order to analyze the payback time or investment capability of the company so as to decide between one measure or another. A market study for possible new tenants for the unused parts of the building is also advisable.

Orientation and external morphology of burrows of the mangrove crab Ucides cordatus (Crustacea: Brachyura: Ucididae)

The aim of the present study was to characterize the external morphology and the orientation of burrows constructed by the mangrove crab Ucides cordatus. Data were obtained from two mangrove forests of similar vegetation dominance (Laguncularia racemosa) but differing in flooding heights. These mangroves were located near Barra de Icapara, Iguape City (SP), Brazil, (24 degrees 50'36 '' S-47 degrees 59'53'W). A total of 221 burrows were examined (120 on the high mangrove and 101 on the low mangrove). External morphology of the burrows was recorded by photographs for categorization and description. The directions of the burrow openings were recorded using a geological compass and the declivities of the ducts were measured with a clinometer. Females constructed 70.8% at Site A and 69.4% at Site B of the occupied burrows with the opening facing the margin of the river (P < 0.001), whilst males showed no significant difference in the burrow orientation (P > 0.05) at either site. In females, the tendency for burrow orientation possibly has a reproductive connotation as larval dispersal may be favoured and enhanced by the tides. Four groups of distinct tracks related to the morphotypes and developmental stages of U. cordatus were observed, No sediment constructions associated with the burrows were recorded for this species. Declivity of the burrows from juveniles was lower than from adults (P < 0.05), probably caused by the differential growth of the chelipeds in this species.

Structural features of the epididymal region of the domestic duck (Anas plathyrynchos)

A região epididimária do pato doméstico era composta pelos ductúlos eferentes, os quais hitotopologicamente foram caracterizados como dúctulos eferentes proximal e distal e, sequencialmente, pelo ducto epididimal. O epitélio dos dúctulos eferentes era pseudo-estratificado, formado por células colunares. O epitélio dos ductos epididimários mostrou-se também pseudo-estratificado, mas não ciliado. de acordo com as análises histomorfométricas, a média da altura epitelial foi significativamente maior nos dútulos esferentes distais, diferindo das baixas médias de altura epitelial observadas nos dúctulos eferentes proximais e ducto epididimal. A média dos diâmetros máximos e mínimos foi significativamente maior nos dúctulos eferentes proximais, comparativamente as médias dos mesmos diâmetros dos outros dúctulos.

Characterisation and vascular expression of nitric oxide synthase 3 in amphibians

In mammals, nitric oxide (NO) produced by nitric oxide synthase 3 (NOS3) localised in vascular endothelial cells is an important vasodilator but the presence of NOS3 in the endothelium of amphibians has been concluded to be absent, based on physiological studies. In this study, a nos3 cDNA was sequenced from the toad, Rhinella marina. The open reading frame of R. marina nos3 encoded an 1170 amino acid protein that showed 81 % sequence identity to the recently cloned Xenopus tropicalis nos3. Rhinella marina nos3 mRNA was expressed in a range of tissues and in the dorsal aorta and pulmonary, mesenteric, iliac and gastrocnemius arteries. Furthermore, nos3 mRNA was expressed in the aorta of Xenopus laevis and X. tropicalis. Quantitative real-time PCR showed that removal of the endothelium of the lateral aorta of R. marina significantly reduced the expression of nos3 mRNA compared to control aorta with the endothelium intact. However, in situ hybridisation was not able to detect any nos3 mRNA in the dorsal aorta of R. marina. Immunohistochemistry using a homologous R. marina NOS3 antibody showed immunoreactivity (IR) within the basal region of many endothelial cells of the dorsal aorta and iliac artery. NOS3-IR was also observed in the proximal tubules and collecting ducts of the kidney but not within the capillaries of the glomeruli. This is the first study to demonstrate that vascular endothelial cells of an amphibian express NOS3.

Étude de mortalité de cinq cancers : mélanome cutané, cancer broncho-pulmonaire, leucémie myéloïde chronique, maladie de Hodgkin et cancer de l’endomètre.

Pour chacun des cinq cancers, nous avons fait un rappel de l’épidémiologie en Amérique du Nord, des classifications et des facteurs pronostics, la description des études, l’étude commentée de la mortalité, et enfin la conclusion. L’étude du mélanome cutané a montré que les mélanomes sont assurables dès les premières années aux stades IA, IB, IIA et IIIA, aux stades IIB, IIC et IIIB après cinq ans et au stade IIIC après 15ans. L’étude du cancer broncho-pulmonaire a montré que le cancer à petites cellules n’est pas assurable et que les cancers broncho-pulmonaires non à petites cellules pourraient être assurables chez les moins de 65 ans aux stades IA à IIIA après dix ans, et chez les 65 ans et plus au stade IA dès les premières années, aux stades IB et IIA après cinq ans et aux stades IIB et IIIA après dix ans L’étude de la leucémie myéloïde chronique a montré l’assurabilité seulement des sujets de plus de 65 ans dès les premières années et des sujets de 60 à 65 ans après 5 ans. L’étude du lymphome de Hodgkin a montré que chez les sujets de moins de 45 ans le stade IA est assurable dès les premières années, les stades IB et IIA le sont après 5 ans et les stades IIB à IVA le sont après 10 ans. Les sujets de 45 à 64 ans aux stades IA et IIA sont assurables dès les premières années et autres stades après 5 ans. Les sujets de 65 ans et plus sont assurables dès les premières années aux stades IA à IIIA et après 5 ans aux autres stades. L’étude du cancer de l’endomètre montre qu’il n’est assurable les cinq premières années que pour le type I au stade I chez les femmes âgées de 45 ans et plus, au stade II chez les femmes de 55 ans et plus et au stade III chez les femmes de 65 ans et plus ; pour le type II au stade I chez les 65 ans et plus, et au stade II chez les 75 ans et plus ; et pour les tumeurs mullériennes malignes mixtes au stade I chez les 65 ans et plus.