Production of a low young modulus titanium alloy by powder metallurgy

Titanium alloys have several advantages over ferrous and non-ferrous metallic materials, such as high strengthto-weight ratio and excellent corrosion resistance. A blended elemental titanium powder metallurgy process has been developed to offer low cost commercial products. The process employs hydride-dehydride (HDH) powders as raw material. In this work, results of the Ti-35Nb alloy sintering are presented. This alloy due to its lower modulus of elasticity and high biocompatibility is a promising candidate for aerospace and medical use. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by isochronal sintering between 900 up to 1600 °C, in vacuum. Sintering behavior was studied by means of microscopy and density. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. Samples sintered at high temperatures display a fine plate-like alpha structure and intergranular beta. A few remaining pores are still found and density above 90% for specimens sintered in temperatures over 1500 °C is reached.

Elastic modulus and hardness of CaTiO3, CaCu3Ti4O12 and CaTiO3/CaCu3Ti4O12 mixture

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Multinodal Load Forecasting in Power Electric Systems using a Neural Network with Radial Basis Function

In this paper we present the results of the use of a methodology for multinodal load forecasting through an artificial neural network-type Multilayer Perceptron, making use of radial basis functions as activation function and the Backpropagation algorithm, as an algorithm to train the network. This methodology allows you to make the prediction at various points in power system, considering different types of consumers (residential, commercial, industrial) of the electric grid, is applied to the problem short-term electric load forecasting (24 hours ahead). We use a database (Centralised Dataset - CDS) provided by the Electricity Commission de New Zealand to this work.

A model to predict R134a refrigerant leakage through the radial clearance of rolling piston compressors

In this paper a non-isothermal two-phase model for oil-R134a refrigerant mixture flow is presented to predict the R134a leakage through the radial clearance of rolling piston compressors. The flow is divided in a liquid single-phase region and in a two-phase region, in which the homogeneous model is used to simulate the flow. The refrigerant leakage is determined using the mixture mass flow rate and the refrigerant mass fraction variation along the flow. The results are obtained for inlet pressures varying from 200 to 700 kPa, inlet temperatures ranging from 40 to 60 degrees C, and minimal clearances between 10 and 60 mu m. The results are firstly compared to existing isothermal model data, showing that there is a significant difference between the leakage flow rates predicted by isothermal and non-isothermal models. Finally, a useful general equation for compressor designers is proposed to calculate the refrigerant leakage for a large range of operation conditions. (C) 2012 Elsevier Ltd and IIR. All rights reserved.

All-Ceramic Crowns Over Single Implant Zircon Abutment. Influence of Young's Modulus on Mechanics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Postfeeding radial dispersal in larvae of Chrysomya albiceps (Diptera : Calliphoridae): implications for forensic entomology

Blowflies utilize discrete and ephemeral breeding sites for larval nutrition. After the exhaustion of food, larvae begin dispersing in search of sites to pupate or additional food sources, a process referred as postfeeding larval dispersal. Some of the most important aspects of this process were investigated in the blowfly Chrysomya albiceps, employing a circular arena to allow radial dispersion of larvae from the center. The results showed a positive correlation between burial depth and distance, and a negative correlation between distance and pupal weight. These results can be used in forensic entomology for the postmortem interval estimation of human corpses in medico-criminal investigations. (c) 2004 Elsevier B.V.. All rights reserved.

Study of the combined radial post-feeding dispersion of the blowflies Chrysomya megacephala (Fabricius) and C. albiceps (Wiedemann) (Diptera, Calliphoridae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo da dispersão larval radial pós-alimentar em Chrysomya megacephala (Fabricius) (Diptera, Calliphoridae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dispersão larval radial pós-alimentar em Lucilia cuprina (Diptera, Calliphoridae): profundidade, peso e distância de enterramento para pupação

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Behavior of the combined radial post-feeding larval dispersal of the blowflies Chrysomya megacephala and Chrysomya albiceps (Diptera, Calliphoridae) and implications for forensic entomology

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Giant monopole resonance and nuclear compression modulus for Ca-40 and O-16

Using a collective potential derived previously on the basis of the generator coordinate method with Skyrme interactions, we obtain values for the compression modulus of Ca-40 which are in good agreement with a recently obtained experimental value. Calculated values for the compression modulus for O-16 are also given. The procedure involved in the derivation of the collective potential is briefly reviewed and discussed.

Numerical simulation of a radial diffuser turbulent airflow

In the present work are presented results from numerical simulations performed with the ANSYS-CFX (R) code. We have studied a radial diffuser flow case, which is the main academic problem used to study the flow behavior on flat plate valves. The radial flow inside the diffuser has important behavior such as the turbulence decay downstream and recirculation regions inside the valve flow channel due to boundary layer detachment. These flow structures are present in compressor reed valve configurations, influencing to a greater extent the compressor efficiency. The main target of the present paper was finding the simulation set-up (computational domain, boundary conditions and turbulence model) that better fits with experimental data published by Tabatabai and Pollard. The local flow turbulence and velocity profiles were investigated using four different turbulence models, two different boundary conditions set-up, two different computational domains and three different flow conditions (Re-in - Reynolds number at the diffuser inlet). We used the Reynolds stress (BSL); the k-epsilon; the RNG k-epsilon; and the shear stress transport (SST) k-omega turbulence models. The performed analysis and comparison of the computational results with experimental data show that the choice of the turbulence model, as well as the choice of the other computational conditions, plays an important role in the results physical quality and accuracy. (c) 2007 Elsevier B.V. All rights reserved.

Blocking Radial Diffusion in a Double-Waved Hamiltonian Model

A non-twist Hamiltonian system perturbed by two waves with particular wave numbers can present Robust Tori, barriers created by the vanishing of the perturbing Hamiltonian at some defined positions. When Robust Tori exist, any trajectory in phase space passing close to them is blocked by emergent invariant curves that prevent the chaotic transport. We analyze the breaking up of the RT as well the transport dependence on the wave numbers and on the wave amplitudes. Moreover, we report the chaotic web formation in the phase space and how this pattern influences the transport.

SECAGEM DE SEMENTES DE SOJA em SILO COM DISTRIBUIÇÃO RADIAL do FLUXO DE AR: I. MONITORAMENTO FÍSICO

O trabalho foi desenvolvido com o objetivo de avaliar a evolução física do processo de remoção de água das sementes em secador estacionário, com cilindro central perfurado e distribuição radical de ar. A pesquisa foi conduzida com sementes de soja, variando o fluxo (26,9, 28,4 e 33,2 m³/minuto/t) e a temperatura do ar insuflado (42, 46 e 50ºC), considerando a posição das sementes (17, 34 e 51 cm em relação ao cilindro de insuflação) e o tempo de secagem (zero a doze horas, com intervalos de duas horas). Foram caracterizados o ar ambiente, o ar insuflado, as temperaturas e os teores de água da massa, as velocidades e curvas de secagem. As avaliações realizadas destacaram vantagens físicas operacionais da combinação de 28,4 m³/minuto/t com 46ºC e o contrário, com a combinação de 26,9 m³/minuto/t com 42ºC.

SECAGEM DE SEMENTES DE SOJA em SILO COM DISTRIBUIÇÃO RADIAL do FLUXO DE AR: II. EFEITOS SOBRE A QUALIDADE DAS SEMENTES

O trabalho avaliou, em sementes de soja, as conseqüências qualitativas provenientes da secagem estacionária com distribuição radial de ar, variando o fluxo (26,9, 28,4 e 33,2 m³/minuto/t) e a temperatura do ar insuflado (42, 46 e 50ºC), considerando a posição das sementes na massa (17, 34 e 51 cm em relação ao cilindro de insuflação) e o tempo de secagem (0 a 12 horas, com intervalos de quatro horas). Para tanto, além das determinações das temperaturas e dos teores de água da massa, foi avaliado o desempenho fisiológico das sementes no início e ao final de seis meses de armazenamento. Apesar das vantagens físicas operacionais resultantes da combinação entre o fluxo e a temperatura intermediários (28,4 m³/minuto/t e 46ºC), a qualidade fisiológica foi menos prejudicada nas combinações dos menores fluxos (26,9 e 28,4 m³/minuto/t) com a maior temperatura (50ºC) e do maior fluxo (33,2 m³/minuto/t) com as menores temperaturas (42 e 46ºC); entre estas, levando em conta os aspectos físico-operacionais, a associação de 28,4 m³/minuto/t com 50ºC foi a mais eficiente na retirada de água das sementes. Assim, admitindo os intervalos de fluxo (26,9 a 33,2 m³/minuto/t) e de temperatura (42 a 50ºC) estudados, conclui-se que a elevação na temperatura demanda redução no fluxo e, inversamente, o aumento no fluxo demanda redução na temperatura.