An efficient flamelet progress-variable method for modeling non-premixed flames in weak electric fields

Combustion stabilization and enhancement of the flammability limits are mandatory objectives to improve nowadays combustion chambers. At this purpose, the use of an electric field in the flame region provides a solution which is, at the same time, easy to implement and effective to modify the flame structure. The present work describes an efficient flamelet progress-variable approach developed to model the fluid dynamics of flames immersed in an electric field. The main feature of this model is that it can use complex ionization mechanisms without increasing the computational cost of the simulation. The model is based on the assumption that the combustion process is not directly influenced by the electric field and has been tested using two chemi-ionization mechanisms of different complexity in order to examine its behavior with and without the presence of heavy anions in the mixture. Using a one- and two-dimensional numerical test cases, the present approach has been able to reproduce all the major aspects encountered when a flame is subject to an imposed electric field and the main effects of the different chemical mechanisms. Moreover, the proposed model is shown to produce a large reduction in the computational cost, being able to shorten the time needed to perform a simulation up to 40 times.Comment: 26 pages, 13 figures, paper accepted for publication on Computers and Fluid

Kinematic and dynamic forcing strategies for predicting the transport of inertial capsules via a combined lattice Boltzmann-Immersed Boundary method

Modeling the transport of deformable capsules under different flow regimens is crucial in a variety of fields, including oil rheology, blood flow and the dispersion of pollutants. The aim of this study is twofold. Firstly, a combined Lattice Boltzmann-Immersed Boundary (LBM-IB) approach is developed for predicting the transport of inertial deformable capsules. A Moving Least Squares (MLS) scheme has been implemented to correlate the pressure, velocity and force fields of the fluid domain with the capsule dynamics. This computational strategy has been named LBM Dynamic IB. Secondly, this strategy is directly compared with a more conventional approach, named LBM Kinematic IB, where capsules move with the same velocity of the surrounding fluid. Multiple test cases have been considered for assessing the accuracy and efficiency of the Dynamic over Kinematic IB scheme, including the stretching of circular capsules in shear flow, the transport in a plane Poiseuille flow of circular and biconcave capsules, with and without inertia. By monitoring the capsule geometry over time, the two schemes have been documented to be in excellent agreement, especially for low Capillary numbers (Ca $\leq$ 0.01), in the case of non-inertial capsules. Despite a moderate increase in computational burden, the presented LBM Dynamic IB scheme is the sole capable of predicting the dynamics of both non-inertial and inertial deformable capsules. The proposed approach can be efficiently employed for studying the transport of blood cells, cancer cells and nano/micro capsules within a capillary flow

Preimplantation biopsy predicts delayed graft function, glomerular filtration rate and long-term graft survival of transplanted kidneys

Background The predictive value of preimplantation biopsies for long-term graft function is often limited by conflicting results. The aim of this study was to evaluate the influence of time-zero graft biopsy histological scores on early and late graft function, graft survival and patient survival, at different time points. Methods We retrospectively analyzed 284 preimplantation biopsies at a single center, in a cohort of recipients with grafts from live and deceased donors (standard and nonstandard), and their impact in posttransplant renal function after a mean follow-up of 7 years (range 1–16). Implantation biopsy score (IBS), a combination score derived from 4 histopathological aspects, was determined from each sample. The correlation with incidence of delayed graft function (DGF), creatinine clearance (1st, 3rd and 5th posttransplant year) and graft and patient survival at 1 and 5 years were evaluated. Results Preimplantation biopsies provided somewhat of a prognostic index of early function and outcome of the transplanted kidney in the short and long term. In the immediate posttransplantation period, the degree of arteriolosclerosis and interstitial fibrosis correlated better with the presence of DGF. IBS values between 4 and 6 were predictive of worst renal function at 1st and 3rd years posttransplant and 5-year graft survival. The most important histological finding, in effectively transplanted grafts, was the grade of interstitial fibrosis. Patient survival was not influenced by IBS. Conclusions Higher preimplantation biopsy scores predicted an increased risk of early graft losses, especially primary nonfunction. Graft survival (at 1st and 5th years after transplant) but not patient survival was predicted by IBS

Writing software or writing scientific articles?

An analysis of publications related to high energy physics computing in refereed journals is presented. The distribution of papers associated to various fields of computing relevant to high energy physics is critically analyzed. The relative publication rate of software papers is evaluated in comparison to other closely related physics disciplines, such as nuclear physics, radiation protection and medical physics, and to hardware publications. The results hint to the fact that, in spite of the significant effort invested in high energy physics computing and its fundamental role in the experiments, this research area is underrepresented in scientific literature; nevertheless the analysis of citations highlights the significant impact of software publications in experimental research

Progettazione di una cassa d’espansione e determinazione della riduzione del rischio idraulico con modellazione 2D

Nell’articolo si studia l’effetto di una cassa d’espansione posta a monte di un’area fluviale soggetta a rischio idraulico. Lo strumento utilizzato è un software bidimensionale sviluppato per simulare la propagazione delle piene fluviali. Il dominio di calcolo è rappresentato da una mesh triangolare non strutturata con una maggiore densità di elementi all’interno dell’alveo e nelle zone immediatamente limitrofe. Per facilitare gli accumuli temporanei di parte dei volumi di piena, si ipotizza la costruzione di un restringimento dell’alveo per mezzo di due pareti verticali che avvicinano le sponde fluviali. Durante la piena, il passaggio per lo stato critico nel restringimento provoca un rigurgito a monte, e quindi un agevole riempimento della cassa d’espansione. La perimetrazione di tale cassa è definita con la costruzione di un rilevato arginale di adeguata altezza. Per meglio simulare il rigurgito a monte della strozzatura, si introduce una scabrezza equivalente negli elementi della strozzatura, per riprodurre le perdite di carico nel restringimento e nel successivo risalto idraulico, malgrado l’ipotesi diffusiva utilizzata nel software di calcolo. La conoscenza delle aree allagate in due eventi di piena storici e dei due relativi idrogrammi di piena, ha consentito la determinazione del coefficiente di Manning quale misura della scabrezza in alveo e fuori alveo. Mediante l’applicazione del modello proposto è possibile validare sia il posizionamento degli argini a monte del restringimento per il contenimento della piena, sia la riduzione delle aree di valle soggette a rischio idraulico

Avaliação da qualidade físico-química da carne bovina proveniente de cruzamento entre raças adaptadas e não adaptadas.

A agropecuária brasileira tem grande importância econômica no país e a pecuária bovina tem grande influência nesse quadro, pois o Brasil é o maior exportador mundial de carne bovina. Dessa maneira, os mercados consumidores mundiais visam à qualidade de tal alimento. Em específico, no caso da carne, os atributos qualitativos mais observados são a palatabilidade (maciez, textura, sabor e suculência) e a aparência (cor, firmeza e marmorização), sendo estes observados através de características físico-química obtidas no músculo . Assim, o objetivo desse trabalho foi avaliar a qualidade físico-química de carne bovina de animais provenientes de diferentes cruzamentos entre mães ½ Angus + ½ Nelore e ½ Simental + ½ Nelore, cruzadas com touros das raças Angus e Wagyu. As análises foram realizadas no Laboratório de Qualidade da Carne da Embrapa Pecuária Sudeste. Foram determinados o pH, a capacidade de retenção de água, a perda por cocção, a cor e a força de cisalhamento. O pH foi medido na porção muscular do bife com um medidor digital. As determinações de cor da carne e da gordura foram realizadas com colorímetro portátil, em diferentes porções do bife. Foram avaliadas: a luminosidade (L*); a intensidade da cor vermelha (a*); e a intensidade da cor amarela (b*). A capacidade de retenção de água foi obtida por diferença entre os pesos de uma amostra de carne, de aproximadamente 2 g, antes e depois de ser submetida à pressão de 10 kg, durante 5 minutos. A perda por cocção foi determinada pela diferença entre os pesos da amostra antes e depois do cozimento. A força de cisalhamento foi medida com o aparelho texturômetro TAXT2 plus. A análise estatística foi realizada utilizando o programa SAS. Os atributos de qualidade que apresentaram interações (p0,05) a capacidade de retenção de água, a intensidade de cor vermelha (a*) na carne, a luminosidade (L*) da cor da gordura e o pH

Desempenho reprodutivo de bovinos na sub-região dos Paiaguas do pantanal Mato-Grossense. I. Efeito da suplementação mineral e da idade de desmama sobre a idade e o peso ao primeiro parto.

Foram estudados os efeitos da suplementação mineral e da idade a desmama sobre a idade e o peso ao primeiro parto de novilhas aneloradas na sub-região de Paiaguas, do Pantanal Mato-Grossense, através de fatorial em delineamento inteiramente casualizado

Where Are My Intelligent Assistant's Mistakes? A Systematic Testing Approach

Intelligent assistants are handling increasingly critical tasks, but until now, end users have had no way to systematically assess where their assistants make mistakes. For some intelligent assistants, this is a serious problem: if the assistant is doing work that is important, such as assisting with qualitative research or monitoring an elderly parent’s safety, the user may pay a high cost for unnoticed mistakes. This paper addresses the problem with WYSIWYT/ML (What You See Is What You Test for Machine Learning), a human/computer partnership that enables end users to systematically test intelligent assistants. Our empirical evaluation shows that WYSIWYT/ML helped end users find assistants’ mistakes significantly more effectively than ad hoc testing. Not only did it allow users to assess an assistant’s work on an average of 117 predictions in only 10 minutes, it also scaled to a much larger data set, assessing an assistant’s work on 623 out of 1,448 predictions using only the users’ original 10 minutes’ testing effort