643 research outputs found

    The influence of self‐weight of elastic 2D structures in topology optimization via numerical technique Smooth Evolutionary Structural Optimization (SESO)

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    O presente artigo aborda a otimização topológica em problemas de elasticidade plana linear considerando a influência do peso próprio nos esforços em elementos estruturais. Utiliza‐se para este fim uma técnica numérica denominada Smooth ESO (SESO) que se baseia no procedimento de diminuição progressiva da contribuição de rigidez de elementos ineficientes com menores tensões até que ele não tenha mais influência. As aplicações do SESO são feitas com o método dos elementos finitos e considera‐se um elemento finito triangular e de alta ordem. Neste trabalho estende‐se a técnica SESO para a aplicação do peso próprio onde o programa, no cômputo de seu volume e peso específico, gera automaticamente uma força concentrada equivalente para cada nó do elemento. A avaliação é finalizada com a definição de um modelo de bielas e tirantes resultante das regiões de concentração de tensões. Nos exemplos de aplicação são apresentadas topologias ótimas de uma estrutura suspensa, de viga baixa e de viga parede considerando o peso próprio e obtendo‐se ótimas configurações e demonstrando que a consideração do peso próprio leva a maior robustez ao processo de otimização.This paper deals with topology optimization in plane elastic‐linear problems considering the influence of the self weight in efforts in structural elements. For this purpose it is used a numerical technique called SESO (Smooth ESO), which is based on the procedure for progressive decrease of the inefficient stiffness element contribution at lower stresses until he has no more influence. The SESO is applied with the finite element method and is utilized a triangular finite element and high order. This paper extends the technique SESO for application its self weight where the program, in computing the volume and specific weight, automatically generates a concentrated equivalent force to each node of the element. The evaluation is finalized with the definition of a model of strut‐and‐tie resulting in regions of stress concentration. Examples are presented with optimum topology structures obtaining optimal settings.Peer Reviewe

    Detection of adulterations in tradictional portuguese game meat products by polymerase chain reaction technique

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    Authenticity assessment and fraud detection in processed meat products have becn attracting an increased attention driven by public health, economic and legal cancems, and also for religiolls reasons. Currcntly, ooe af the major issues conceming adulterations in the meat indust:ry regards the fraudulent substitution af higher commercial valued meat species by less expensive oDes [1]. The manufacture af traditional meat products is a long-established practice in the Northeast of Portugal. One of the most appreciated products is called "Alheiras", which are traditional smoked fermented sausages, mainly produced with pork and poultry meat. In addition to the two Portuguese Alheiras with Protected Geographical Indication (pGI), other types of "Alheiras" are now available in the market, including the ones produced with game meat. Due to the game meat particular taste, intense Oavour and seasonality, it generally eommands higher prices compared to other meats [1]. Sinee game meat "Alheiras" should, totally or partially, include different types of game meat, they are particularly prone to fraudulent meat substitutions

    Species identification and authentication of hare (Lepus) meat by the use of the mitochondrial cytb gene

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    Nowadays, consumers are increasingly concerned with issues of food safety and authenticity. In particular, game meat has been much appreciated by consumers for their exotic flavour and texture, low in fat and cholesterol as well as by the absence of steroids or other drugs. Food authenticity assessment is important in that it avoids unfair competition among producers and allows consumers to have accurate information about the products they purchase. Therefore, it is important to ensure that species of high commercial value declared are not replaced by other species of lesser value [I]

    THE MECHANISTIC INVESTIGATION FOR THE POSSIBILITY OF THE USE OF CoO(OH) AS AN ELECTRODE MODIFIER FOR ANALYSIS OF COMPLEX-FORMING SUBSTANCES

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    The possibility of the use of cobalt (III) oxyhydroxide as an electrode modifier for electrochemical detection of complex-forming compounds was evaluated by means of mechanistic investigation. The corresponding mathematical model has been developed and analyzed, by means of linear stability theory and bifurcation analysis. It was detected, that the steady-state stability topological region for this case is wider, than for cases, in which the complex-forming compound interferes the analysis of another compound. The possibility of oscillatory and monotonic instabilities for this system has also been evaluate

    Authentication of a traditional game meat sausage (Alheira) by species-specific PCR assays to detect hare, rabbit, red deer, pork and cow meats

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    Alheira is a traditional meat product that is typical from the Northeast region of Portugal and much appreciated. It is a sort of sausage produced industrially or by small artisanal producers, having wheat bread and meats as main ingredients. Game meat Alheira (Alheira de caça) is considered one of the most attractive products since it should include different game meats. The aim of the present work was to identify the species of origin of meats added to game meat Alheira samples to verify their compliance with labelling. Species-specific PCR assays targeting mitochondrial genes of rabbit, hare, red deer, cow and pork were optimised and applied to industrial and artisanal samples. The assays revealed adequate specificity for each of the targeted species, with sensitivities of 0.01-0.1%. Results of the evaluation of 18 commercial samples identified several inconsistencies with labelling, namely the absence of declared game species (red deer, hare and rabbit) in ten samples and the presence of undeclared cow species in nine of the analysed samples. These findings indicate the occurrence of misleading labelling, suggesting the adulteration by substitution of game meats by cow meat to reduce production costs and the need to protect and valorise this kind of traditional food product.The authors acknowledge the financial support of the University of Porto/Santander Totta “Projectos pluridisciplinares 2010” and the Fundação para a Ciência e a Tecnologia (FCT) through grant no. PEst-C/EQB/LA0006/2013.info:eu-repo/semantics/publishedVersio

    Identification of duck, partridge, pheasant, quail, chicken and turkey meats by species-specific PCR assays to assess the authenticity of traditional game meat Alheira sausages

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    Game meat Alheira (Alheira de caça) sausage is a traditional fermented product typical from the Northeast region of Portugal, having bread and meats (including game) as main ingredients. It is a particularly appreciated product by consumers that commands higher prices, especially in comparison with the common Alheira produced with pork and poultry meats. Following our previous work in which several mammalian game meat species were successfully identified in game meat Alheira sausages for authentication purposes, the present work aimed at identifying game bird's species for the overall assessment of labelling compliance. For that purpose, several species-specific PCR assays targeting mitochondrial DNA for the detection of game and domestic bird's meat, namely duck, partridge, pheasant, quail, chicken and turkey were developed, optimised and applied to commercial samples of game meat Alheira for their authentication. The assays revealed a high specificity and sensitivity to detect the addition of all evaluated species down to a level of 0.01% (w/w). PCR results indicated the existence of several inconsistencies with the labelled information, namely the absence of declared game species (duck, partridge and pheasant) and the presence of undeclared poultry meat, pointing out to adulterations owing to substitution of game by domestic meat species. Since this is considered a high-valued traditional product that should be valorised and protected, this work puts in evidence the need for inspection programs to enforce regulation. © 2014 Elsevier Ltd.The authors acknowledge the financial support of the University of Porto/Santander Totta “Projectos pluridisciplinares 2010” and the Fundação para a Ciência e a Tecnologia (FCT) through grant no. PEst-C/EQB/LA0006/2013.info:eu-repo/semantics/publishedVersio

    Effects of air temperature on physiology and productive performance of pigs during growing and finishing phases

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    Thirty-six castrated male pigs were used to determine the influence of thermal environment and reduction of consumption on performance and carcass composition. Animals were housed in two climate chambers. In one, animals were in thermal comfort (TN) (22 °C), and in the other, pigs were under heat stress (HS) (34 °C). Animals were distributed in a randomized block design, making three treatments (TN, HS and animals in thermal comfort with food consumption paired with that observed in HS (PFTN)), with six replicates and two animals per experimental unit. Data were obtained on performance and carcass composition. The weight gains of HS and PFTN animals were reduced by 40.5% and 34.7%, respectively, reflecting a reduction of 13.2% in the final weight of PFTN animals. Triiodothyronine concentration was not affected by heat, but there was an increase in lymphocyte numbers in PFTN animals. The HS and PFTN animals showed lower hot carcass weight. However, there were no effects on hot carcass yield and relative weights of heart, lung and spleen. Heat stress compromised performance. The negative effects of high temperature on pigs include reduction in feed intake and changes in physiology.Keywords: Environment, heat stress, pair feed, pig growth, pig productio

    Detecção de adulterações em alheiras de caça: identificação de carne de aves com base em marcadores moleculares

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    A avaliação da autenticidade de produtos cárneos inclui diferentes aspectos, como a substituição de carnes com valor económico elevado, por outras de menor valor, e a presença de espécies não declaradas no rótulo [I]. Actualmente, para além da Alheira tradicional, produzida à base de carne de porco e/ou de aves (galinha e peru) são comercializadas Alheiras de caça, geralmente com preço mais elevado. Neste tipo de produtos processados, torna-se difícil a diferenciação das carnes utilizadas, pelo que são propícios a adulterações. Várias técnicas analíticas com base na detecção de proteínas (cromatográficas, electroforéticas e imunológicas) têm sido aplicadas na identificação de espécies em produtos cárneos. Devido à maior estabilidade do DNA, comparativamente com as proteínas, a sua utilização como molécula alvo através da técnica de reacção em cadeia da polimerase (PCR) apresenta-se como uma alternativa específica, rápida e sensível, mais adequada para a identificação de espécies em alimentos processados. Neste trabalho, propõe-se a identificação de espécies de aves (galinha, peru, faisão, perdiz e pato) em Alheiras de caça pela técnica de PCR. Prepararam-se misturas padrão contendo quantidades conhecidas de cada carne em estudo e procedeu-se à extracção de DNA pelo método Wizard [2]. O rendimento de extracção e a pureza dos extractos foram avaliados por espectrofotometria. Para a detecção de carne de perdiz e fa isão, utilizaram-se primers específicos para o gene mitocondrial 12S rRNA [1]. Para a detecção de peru, galinha e pato, foram desenhados primers específicos tendo como alvo o gene cytb. Os resultados demonstraram a especificidade e sensibilidade das reacções, permitindo detectar a adição de todas as espécies em carne de porco até ao nível de 0,01 %, à excepção do peru (0,1%). As metodologias propostas foram aplicadas com sucesso a 15 amostras comerciais de alheiras de caça, tendo-se detectado várias inconsistências na rotulagem, como a ausência de espécies de caça declaradas (faisão, perdiz e pato) e a presença de carnes (galinha e peru) não rotuladas

    Production of electroweak bosons in e+e- annihilation at high energies

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    Production of electroweak bosons in e+e- annihilation into quarks and into leptons at energies much greater than 100 Gev is considered. We account for double-logarithmic contributions to all orders in electroweak couplings. It is assumed that the bosons are emitted in the multi-Regge kinematics. The explicit expressions for the scattering amplitudes of the process are obtained. It is shown that the cross sections of the photon and Z production have the identical energy dependence and asymptotically their ratio depends only on the Weinberg angle whereas the energy dependence of the cross section of the W production is suppressed by factor s^{-0.4} compared to them.Comment: Revtex4, 16 pages, 7 figures, 2 table
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