Investigation on numerical schemes in the simulation of barotropic cavitating flows

A numerical methodology for the simulation of cavitating flows is considered. A homogeneous-flow cavitation model, accounting for thermal effects and active nuclei concentration, is considered, which leads to a barotropic state law. The continuity and momentum equations for compressible inviscid flows are discretized through a finite-volume approach, applicable to unstructured grids. The numerical fluxes are computed by shockcapturing schemes and adhoc preconditioning is used to avoid accuracy problems in the low-Mach regime. Second-order accuracy in space is obtained through MUSCL reconstruction. Time advancing is carried out by an implicit linearized scheme. Two different numerical fluxes are investigated here, viz. the Roe and the Rusanov schemes. For the Rusanov flux two different time linearizations are proposed; in the first one the upwind part of the flux function is frozen in time, while in the second one its time variation is taken into account, although in an approximated manner. The different schemes and the different linearizations are appraised for the quasi 1D-flow in a nozzle through comparison against exact solutions and for the flow around a hydrofoil mounted in a wind tunnel through comparison against experimental data. Non-cavitating and cavitating conditions are simulated. It is shown that, for cavitating conditions, the Rusanov scheme together with the more complete time linearization allows time steps much larger than for the Roe scheme to be used. Finally, the results obtained with this scheme are in good agreement with the exact solutions or the experimental data for all the considered test cases.http://deepblue.lib.umich.edu/bitstream/2027.42/84242/1/CAV2009-final42.pd

A Preconditioned implicit Roe's scheme for barotropic flows: towards simulation of cavitation phenomena

The discretisation of the Euler equations for a barotropic state law is considered. An upwind scheme based on the definition of a Roe's type matrix is first obtained for this particular hyperbolic problem. A low Mach number asymptotic study is performed both in the continuous and discrete case showing that the discrete solution admits pressure fluctuations in space much larger than those of the exact one. This is the same kind of behaviour observed for the case of a polytropic state law. A preconditioning is then applied such that the obtained discrete formulation has an asymptotic behaviour in agreement with the continuous case. A linearised implicit scheme is defined using the properties of the Roe matrix instead of the first-order homogeneity of the flux function which is not satisfied here. The implicit formulation is also extended to the preconditioned scheme. All the proposed ingredients are validated in the case of a quasi 1-D nozzle flow of a cavitating liquid

Model Driven Engineering Benefits for High Level Synthesis

This report presents the benefits of using the Model Driven Engineering (MDE) methodology to solve major difficulties encountered by usual high level synthesis (HLS) flows. These advantages are highlighted in a design space exploration environment we propose. MDE is the skeleton of our HLS flow dedicated to intensive signal processing to demonstrate the expected benefits of these software technologies extended to hardware design. Both users and designers of the design flow benefit from the MDE methodology, participating to a concrete and effective advancement in the high level synthesis research domain. The flow is automatized from UML specifications to VHDL code generation and has been successfully evaluated for the conception of a video processing application

Upwind stabilization of Navier-Stokes solvers

We present a study of the effect of upwinding on stabilisation of both advective and pressure terms in a family of primitive-variable Navier-Stokes solvers. We consider two MUSCL schemes, the first one applies to compressible flow, the second one to incompressible flow. We illustrate the fact that both numerical models suffer oscillations if a minimal (but not large) amount of upwinding is not associated with acoustics, while advection can be stabilized by the physical diffusion terms when the mesh Reynolds number is small enough

Energia e inovação.

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Sócio-Econômico. Economia.Durante as últimas décadas evidenciou-se a necessidade da transição energética, tanto para frear os impactos do Aquecimento Global, como para produzir uma matriz energética sustentável. Nesse contexto, percebe-se diferentes abordagens ao problema, tanto em nível nacional com políticas públicas, como internacional com Acordos Internacionais. Isto posto, verifica-se através dos estudos de diferentes agentes formadores de opinião no setor energético mundial, como através de indicadores utilizados pela Organização das Nações Unidas, que os objetivos estabelecidos para 2050 na seara energética não serão atingidos sem o amparo da Inovação

Avaliação das propriedades de coagulação de leite bovino in natura por parâmetros latodinamográficos e reológicos

Orientadora : Profª. Drª. Nina WaszczynskyjCoorientador : Prof. Dr. Alessandro NogueiraTese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia de Alimentos. Defesa: Curitiba, 13/12/2017Inclui referências : f. 87-100Resumo: A produção de leite é uma atividade importante em diversos países do mundo. No Brasil, 4º maior produtor mundial (ano de 2015), o leite está entre os principais produtos da agropecuária. Com o aumento no volume de leite, a produção de derivados lácteos como os queijos vem crescendo. Porém, nem todo leite é adequado para produção de queijo, alguns são mais aptos à coagulação que outros, sendo sua composição e algumas características como as propriedades de coagulação do leite (PCL) fatores importantes para o processo tecnológico e para o rendimento econômico do laticínio. Desta forma, é interessante estudar e avaliar a capacidade de coagulação do leite a fim aperfeiçoar o destino do mesmo, bem como contribuir com estudos para melhoria genética de bovinos de leite. O presente estudo foi composto pela revisão de literatura e dois experimentos. No experimento 1 foram analisadas amostras de leite provenientes de vacas da raça Holandesa de seis rebanhos distintos da província de Veneza-Itália, em dois períodos do ano: verão (julho a setembro) e outono (setembro a dezembro). Todas as amostras foram submetidas às análises de gordura, proteína total, caseína, pH por espectroscopia no infravermelho médio; contagem de células somáticas por fluorescência ótica e propriedades de coagulação do leite, expressas em tempo para o início da coagulação enzimática (TCE, min) e consistência do coágulo após 30 minutos da adição do coalho (A30, mm) por latodinamografia. Foram também determinados os índices de aptidão de coagulação do leite (IAC) e de temperatura e umidade (ITU). Do total de amostras analisadas, 41,2% não coagularam (NC) nos 30 minutos de análise. O maior percentual de amostras coaguladas foi para as coletadas durante o outono, período que os valores para o ITU foram mais baixos. Os dados obtidos nesse trabalho demonstram um elevado número de amostras NC, constando-se que provavelmente as condições climáticas influenciaram a capacidade de coagulação. No experimento 2 foram avaliadas amostras de leite de dezessete animais das raças Holandesa e mestiças Jersey-Holanda de um rebanho localizado na cidade de Ponta Grossa, Paraná-Brasil. Foram analisadas as propriedades reológicas da coagulação enzimática do leite, em três períodos do ano (maio, agosto e dezembro). O teor de gordura, proteína total, caseína, lactose, contagem de células somáticas e o ITU foram determinadas pelos mesmos procedimentos do experimento 1 e o pH com uso de pHmetro. As propriedades reológicas (tempo de coagulação enzimática e a força da coalhada) foram determinadas por reometria em regime oscilatório de baixa amplitude por meio dos módulos G' (de armazenamento), G'' (de perda) e da tan ? (tangente de perda). A partir de amostras do sangue dos animais, foram determinados os genótipos para ?appa-caseína (?-CN), betacaseína (?-CN) e beta-lactoglobulina (?-Lg) pela técnica de PCR-RFLP. Foram encontradas diferenças entre a composição dos leites nos diferentes períodos de análise, bem como no perfil reológico. Com exceção das amostras de leite de um animal, ambos G' e G'' aumentaram com o tempo, comportamento esperado e de acordo com a literatura, porém apresentaram característica de gel fraco. Com relação ao perfil proteico foram encontrados os genótipos AA; AB e BB para ?-CN; A1A2 e A2A2 para a ?-CN e AA; AB e BB para ?-Lg, porém não foi estabelecida uma relação direta com as propriedades de coagulação e com o TCE. Os resultados obtidos nos 2 experimentos apontam a necessidade de estudos com relação à PCL a fim de garantir um leite de qualidade para a produção de queijos e que a determinação do teor de proteína total ou caseína não são suficientes para determinar essas propriedades. Também foi possível notar que o estresse térmico tem influência negativa sobre a PCL. Para indústria de queijos, longo TCE é o resultado de reduzida velocidade de formação do coágulo com fraca consistência final o que pode resultar em perdas no rendimento e na qualidade global principalmente para queijos maturados. Palavras-chave: Coagulação do leite. Tempo de coagulação. Reologia. Queijos.Abstract:Milk production is an important activity in various countries throughout the world. In Brazil, the 4th largest world producer (year 2015), milk is amongst the main agricultural products, and with the increase in the milk volume, the production of dairy products such as cheeses has also grown. However not all milk is adequate for cheese production, some being more apt for coagulation than others. Thus for cheese production the composition of the milk and some of its characteristics, such as the milk coagulation properties (MCP), are important for the technological process and for the economic yield of the dairy. It is therefore of interest to study and evaluate the coagulation capacity of the milk so as to perfect its destiny, and contribute to studies for the genetic improvement of dairy cattle. The present study consisted of two experiments. In the first experiment milk samples from Holstein cows in six distinct herds in the province of Venice-Italy in two periods of the year: summer (July to September) and autumn (September to December), were analyzed. All the samples were analyzed for their fat, total protein and casein contents and pH value by medium infrared spectroscopy; somatic cell count by optical fluorescence; and the milk coagulation properties by lactodynamography and expressed as the milk rennet coagulation time (RCT, min) and curd firmness (A30, mm), 30 minutes after the addition of the rennet. The milk coagulation aptitude index (IAC) and temperature-humidity index (THI) were also determined. Of the total number of samples analyzed, 41.2% did not coagulate (NC) during the 30 minutes of analysis. The majority of the samples that did coagulate were taken in the autumn, period during which the THI values were lower. The data obtained in this study demonstrated an elevated number of NC samples, so probably the climatic conditions influenced the coagulation capacity. In experiment 2, milk samples from seventeen animals of Holstein and mixed Jersey-Holstein breeds from a herd located in the city of Ponta Grossa, Paraná, Brazil, were evaluated. The rheological properties of the milk rennet coagulation were analyzed at three periods during the year (May, August and December). The fat, total protein and casein contents and the somatic cell counts and THI were determined using the same procedures used in experiment 1 and the pH measured using a pHmeter. The rheological properties (rennet coagulation time and curd firmness) were determined by rheometry using a low amplitude oscillatory regime by way of the storage modulus (G'), loss modulus (G") and the loss tangent (tan ?). The genotypes for ?appa-casein (?-CN), beta-casein (?-CN) and beta-lactoglobulin (?-Lg) were determined from the animals' blood samples using the PCR-RFLP technique. Differences were found in the compositions of the milks obtained during the different periods of analysis, and also in the rheological profiles. With the exception of the milk samples from one animal, the values for both G' and G" increased with time, behavior expected and in agreement with the literature, since they present the characteristics of a weak gel. With respect to the protein profile the following genotypes were found: AA; AB and BB for ?-CN; A1A2 and A2A2 for ?-CN and AA; AB and BB for ?-Lg, although a direct relationship was not established with the coagulation properties or with RCT. The results of the 2 experiments show the need for studies in relation to the MCP so as to guarantee milk with adequate quality for cheese production, and also that the determination of the total protein or casein contents were not sufficient to determine these parameters. It was also possible to note that heat stress had a negative influence on MCP. For the cheese industry, a long RCT is the result of a reduced coagulum formation velocity with a weak final consistency, which can result in losses in yield and in overall quality, principally for matured cheeses. Keywords: Milk coagulation. Coagulation time. Rheology.Cheeses

FPGA Configuration of Intensive Multimedia Processing Tasks Modeled in UML

Recent research have demonstrate interests in a codesign framework     that allows description refinement at different abstraction level.     We have proposed such a framework that allows SoC resources     allocation for regular and repetitive tasks found in intensive     multimedia applications. Nevertheless, the framework does not directly target     reconfigurable architectures, the difficult job of placing and     routing an application on a FPGA being postponed to a dedicated     tool. In order to limit the number of synthesis on this external     tool, we propose an algorithm that, from a high level description     of an intensive multimedia application, estimates the resource     usages on a given FPGA architecture. This algorithm makes use of a     simple mathematical formalism issued from case study     implementations

Effect of THI on milk coagulation properties of Holstein-Friesian dairy cattle

ABSTRACT The objective of this study was to evaluate the effect of temperature-humidity index (THI) on the milk coagulation properties of Holstein-Friesian dairy cattle from northeast part of Italy. A total of 592 individual milk samples from six dairy herds were evaluated. The milk coagulation properties traits analysed were milk rennet coagulation time and curd firmness, as well as the fat, protein, and casein contents, pH, milk aptitude to coagulate (IAC), and the somatic cell count. The THI was determined during the periods of sample collection. The THI results showed that values of up to 75 did not significantly change the IAC values; however, when the THI values were above 75, the IAC decreased significantly. The control of THI can be used to guarantee appropriate milk coagulation properties

Stochastic Computing with Integrated Optics

Stochastic computing (SC) allows reducing hardware complexity and improving energy efficiency of error resilient applications. However, a main limitation of the computing paradigm is the low throughput induced by the intrinsic serial computing of bit-streams. In this paper, we address the implementation of SC in the optical domain, with the aim to improve the computation speed. We implement a generic optical architecture allowing the execution of polynomial functions. We propose design methods to explore the design space in order to optimize key metrics such as circuit robustness and power consumption. We show that a circuit implementing a 2 nd order polynomial degree function and operating at 1Ghz leads to 20.1pJ laser consumption per computed bit

Complementary Communication Path for Energy Efficient On-Chip Optical Interconnects

International audienceOptical interconnects are considered to be one of the key solutions for future generation on-chip interconnects. However, energy efficiency is mainly limited by the losses incurred by the optical signals, which considerably reduces the optical power received by the photodetectors. In this paper we propose a differential transmission of the modulated signals, which contributes to improve the transmission of the optical signal power on the receiver side. With this approach, it is possible to reduce the input laser power and increase the energy efficiency of the optical communication. The approach is generic and can be applied to SWSR-, MWSR-, SWMR- and MWMR-like architectures