Estudo da redução de arrasto induzido por polímeros em escoamentos internos turbulentos em dutos

The flows turbulent and laminar are present in various applications of engineering and one of the villain of energy loss big is the surface friction. Currently, there are several research aimed for the study of reducing drag (DR) with the objective of developing effective methods to reduce the friction. Regardless of numerous research carried out until today, the phenomenon DR still remains in study not it is fully understood. This paper studied the drag reduction by polymer induction in turbulent internal flows in ducts. We constructed a testing bench to perform the analysis of drag reduction, the bench has basically two manometers with a 8.5 psi full scale, a peripheral pump 0.5 HP, an acrylic tank, valves and tubes pvc and is situated in the Laboratory Fluid Mechanics UFRN. Were used as polymer additives to polyethylene glycol 4000, the Polyox WSR N60K, Polyox WSR 301 and Polyox WSR 205. The rationale for the choice of these polymers is their wide application in situations requiring greater energy efficiency, such as the addition reducing polymers for the jet used by the fire department to achieve greater distances. The induced drag reduction polymers is investigated from the turbulent flow analysis, with Reynolds number in a range between 2×104

Estudo da redução de arrasto induzido por polímeros em escoamentos internos turbulentos em dutos

The flows turbulent and laminar are present in various applications of engineering and one of the villain of energy loss big is the surface friction. Currently, there are several research aimed for the study of reducing drag (DR) with the objective of developing effective methods to reduce the friction. Regardless of numerous research carried out until today, the phenomenon DR still remains in study not it is fully understood. This paper studied the drag reduction by polymer induction in turbulent internal flows in ducts. We constructed a testing bench to perform the analysis of drag reduction, the bench has basically two manometers with a 8.5 psi full scale, a peripheral pump 0.5 HP, an acrylic tank, valves and tubes pvc and is situated in the Laboratory Fluid Mechanics UFRN. Were used as polymer additives to polyethylene glycol 4000, the Polyox WSR N60K, Polyox WSR 301 and Polyox WSR 205. The rationale for the choice of these polymers is their wide application in situations requiring greater energy efficiency, such as the addition reducing polymers for the jet used by the fire department to achieve greater distances. The induced drag reduction polymers is investigated from the turbulent flow analysis, with Reynolds number in a range between 2×104

Histopathology findings in common marmosets (Callithrix jacchus Linnaeus, 1758) with chronic weight loss associated with bile tract obstruction by infestation with Platynosomum (Loos, 1907)

Chronic weight loss in marmosets is often associated with wasting marmoset syndrome (WMS), an important disease that occurs in callitrichid colonies around the world. Even though its etiology is very difficult to determine, particular variables, such as weight loss, diarrhea and alopecia, associated or not with infestation in the pancreatic ducts with Trichospirura leptossoma (Nematoda: Thelazioidea), seem to be linked with the syndrome. This study investigated the histopathology of the lungs, duodenum, liver, gallbladder, extrahepatic bile ducts and pancreatic ducts of six common marmosets (Callithrix jacchus) suffering from severe non-diarrheic weight loss. Three individuals died naturally and the other three were euthanized. Microscopic findings showed the presence of adult flukes (Platynosomum) in the liver. These flukes, which provoke common infection in cats, were also observed inside the gallbladder as well as in the intra and extrahepatic bile ducts in common marmosets. Portal fibrosis was observed in two animals, which developed chronic fibrosing hepatopathy (biliary pattern, grade 3). The disease progresses without diarrhea and without pancreatic lesions or infestation. With the rogression, the animals presented with ascending cholangitis, cholestasis and portal fibrosis, sometimes culminating in secondary biliary cirrhosis. Therefore, this nfirmity, associated with chronic weight loss in common marmosets, could be another tiological factor linked with WMS

Oil Flow Rate Measurements Using 198au And Total Count Technique

In industrial plants, oil and oil compounds are usually transported by closed pipelines with circular cross-section. The use of radiotracers in oil transport and processing industrial facilities allows calibrating flowmeters, measuring mean residence time in cracking columns, locate points of obstruction or leak in underground ducts, as well as investigating flow behavior or industrial processes such as in distillation towers. Inspection techniques using radiotracers are non-destructive, simple, economic and highly accurate. Among them, Total Count, which uses a small amount of radiotracer with known activity, is acknowledged as an absolute technique for flow rate measurement. A viscous fluid transport system, composed by four PVC pipelines with 13m length (12m horizontal and 1m vertical) and ½, ¾, 1 and 2-inch gauges, respectively, interconnected by maneuvering valves was designed and assembled in order to conduct the research. This system was used to simulate different flow conditions of petroleum compounds and for experimental studies of flow profile in the horizontal and upward directions. As 198Au presents a single photopeak (411,8 keV), it was the radioisotope chosen for oil labeling, in small amounts (6 ml) or around 200 kBq activity, and it was injected in the oil transport lines. A NaI scintillation detector 2”x 2”, with well-defined geometry, was used to measure total activity, determine the calibration factor F and, positioned after a homogenization distance and interconnected to a standardized electronic set of nuclear instrumentation modules (NIM), to detect the radioactive cloud.

Histopathology findings in common marmosets (Callithrix jacchus Linnaeus, 1758) with chronic weight loss associated with bile tract obstruction by infestation with Platynosomum (Loos, 1907)

Chronic weight loss in marmosets is often associated with wasting marmoset syndrome (WMS), an important disease that occurs in callitrichid colonies around the world. Even though its etiology is very difficult to determine, particular variables, such as weight loss, diarrhea and alopecia, associated or not with infestation in the pancreatic ducts with Trichospirura leptossoma (Nematoda: Thelazioidea), seem to be linked with the syndrome. This study investigated the histopathology of the lungs, duodenum, liver, gallbladder, extrahepatic bile ducts and pancreatic ducts of six common marmosets (Callithrix jacchus) suffering from severe non-diarrheic weight loss. Three individuals died naturally and the other three were euthanized. Microscopic findings showed the presence of adult flukes (Platynosomum) in the liver. These flukes, which provoke common infection in cats, were also observed inside the gallbladder as well as in the intra and extrahepatic bile ducts in common marmosets. Portal fibrosis was observed in two animals, which developed chronic fibrosing hepatopathy (biliary pattern, grade 3). The disease progresses without diarrhea and without pancreatic lesions or infestation. With the rogression, the animals presented with ascending cholangitis, cholestasis and portal fibrosis, sometimes culminating in secondary biliary cirrhosis. Therefore, this nfirmity, associated with chronic weight loss in common marmosets, could be another tiological factor linked with WMS

Biliary duct injuries in the laparoscopic era: our experience

Aim. The main aim of our study is to evaluate the incidence, the type, the causes and the therapy of biliary duct injuries which occurred after the video laparoscopic cholecystectomies performed in our Department during the period from 1990 to 2012. Patients and methods. A retrospective analysis of 1186 VLC has been made in our Department from March 1990 to June 2012. Before the cholecystectomy all patient were evaluated with trans abdominal echography. Beyond the incidence of BDI was evaluated damaging mechanism, etiology, therapy and time of diagnosis. Results. From 1990 to 2012 a total of 9 BDIs occurred, with an incidence of 0,75%. Out of 9 patients 4 had major lesions and 5 had minor lesions; the most common BDI was Strasberg A (45%), the most common etiology was the presence of anatomical variations. In four cases the diagnosis has been intraoperative, in five cases has been postoperative. Conclusions. Our clinical experience shows that the main cause of BDI are the surgeon experience and the bile ducts anatomical variation.

Shock Train/Boundary-Layer Interaction in Rectangular Scramjet Isolators

Numerous studies of the dual-mode scramjet isolator, a critical component in preventing inlet unstart and/or vehicle loss by containing a collection of flow disturbances called a shock train, have been performed since the dual-mode propulsion cycle was introduced in the 1960s. Low momentum corner flow and other three-dimensional effects inherent to rectangular isolators have, however, been largely ignored in experimental studies of the boundary layer separation driven isolator shock train dynamics. Furthermore, the use of two dimensional diagnostic techniques in past works, be it single-perspective line-of-sight schlieren/shadowgraphy or single axis wall pressure measurements, have been unable to resolve the three-dimensional flow features inside the rectangular isolator. These flow characteristics need to be thoroughly understood if robust dual-mode scramjet designs are to be fielded. The work presented in this thesis is focused on experimentally analyzing shock train/boundary layer interactions from multiple perspectives in aspect ratio 1.0, 3.0, and 6.0 rectangular isolators with inflow Mach numbers ranging from 2.4 to 2.7. Secondary steady-state Computational Fluid Dynamics studies are performed to compare to the experimental results and to provide additional perspectives of the flow field. Specific issues that remain unresolved after decades of isolator shock train studies that are addressed in this work include the three-dimensional formation of the isolator shock train front, the spatial and temporal low momentum corner flow separation scales, the transient behavior of shock train/boundary layer interaction at specific coordinates along the isolator's lateral axis, and effects of the rectangular geometry on semi-empirical relations for shock train length prediction. A novel multiplane shadowgraph technique is developed to resolve the structure of the shock train along both the minor and major duct axis simultaneously. It is shown that the shock train front is of a hybrid oblique/normal nature. Initial low momentum corner flow separation spawns the formation of oblique shock planes which interact and proceed toward the center flow region, becoming more normal in the process. The hybrid structure becomes more two-dimensional as aspect ratio is increased but corner flow separation precedes center flow separation on the order of 1 duct height for all aspect ratios considered. Additional instantaneous oil flow surface visualization shows the symmetry of the three-dimensional shock train front around the lower wall centerline. Quantitative synthetic schlieren visualization shows the density gradient magnitude approximately double between the corner oblique and center flow normal structures. Fast response pressure measurements acquired near the corner region of the duct show preliminary separation in the outer regions preceding centerline separation on the order of 2 seconds. Non-intrusive Focusing Schlieren Deflectometry Velocimeter measurements reveal that both shock train oscillation frequency and velocity component decrease as measurements are taken away from centerline and towards the side-wall region, along with confirming the more two dimensional shock train front approximation for higher aspect ratios. An updated modification to Waltrup \& Billig's original semi-empirical shock train length relation for circular ducts based on centerline pressure measurements is introduced to account for rectangular isolator aspect ratio, upstream corner separation length scale, and major- and minor-axis boundary layer momentum thickness asymmetry. The latter is derived both experimentally and computationally and it is shown that the major-axis (side-wall) boundary layer has lower momentum thickness compared to the minor-axis (nozzle bounded) boundary layer, making it more separable. Furthermore, it is shown that the updated correlation drastically improves shock train length prediction capabilities in higher aspect ratio isolators. This thesis suggests that performance analysis of rectangular confined supersonic flow fields can no longer be based on observations and measurements obtained along a single axis alone. Knowledge gained by the work performed in this study will allow for the development of more robust shock train leading edge detection techniques and isolator designs which can greatly mitigate the risk of inlet unstart and/or vehicle loss in flight.

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.