This thesis is focused on analyzing pitch as one of the key parameters in manufacturing hydraulic hoses. Data for this analysis was acquired directly on site at Semperflex Optimit s.r.o. In this paper, a description of processes will be provided, and the influence of these processes on the pitch will be investigated. During this analysis two processes were found to have the greatest influence on the pitch and improvements were suggested. Using the Gauge R&R method, the precision of the measuring system was assessed and the appropriate adjustments were made.

Med utgångspunkt i den analoga animationsstilen ”rubber hose” från tidigt 1900-tal undersöker den här uppsatsen vilka spår av den mänskliga handen som människor uppfattar i analog respektive digital animation. Hur värdesätter man de två olika sätten att animera och vilken syn har man på rubber hose som animationsstil? Två nygjorda animationer i rubber hose-stilen, skapade analogt respektive digitalt, samt en autentisk animation av karaktären Mickey Mouse är utgångspunkten i en enkätundersökning med följande forskningsfrågor och svar: Hur ser respondenterna på rubber hose-stilen? Rubber hose är fortfarande bekant och uppfattas som relevant men inte nödvändigtvis i analogt animerad form. Vilka eventuella spår av animatören uppfattade respondenterna i den analoga respektive digitala animationen? Skärpa, pennstreck och bakgrundens ”smutsighet” är några exempel på upplevda spår av animatören i de analoga animationerna. Dock har respondenterna svårare att uppfatta spår i den digitala animationen. Hur påverkas respondenternas upplevelse av en animation av om den är analoga eller digital? En majoritet av respondenterna anser att den digitala animationen har högra kvalité men att den analoga har charm och ger nostalgi. En slutsats man kan dra av undersökningen är att rubber hose-stilen fortfarande uppskattas men att animatören genom att åtminstone delvis ta till digitala medel både kan underlätta processen och behålla känslan

Denna rapport presenterar ett examensarbete inom ämnet produktutveckling vid Kungliga Tekniska Högskolan. Arbetet utfördes på uppdrag av företaget Weda AB som tillverkar rengöringslösningar under vatten där en befintlig slanganslutning mellan robot och slang skulle utvecklas. Målet med detta projekt var att vidareutveckla slanganslutningen så att denna avlastar slangen samt konstruera en billigare slanganslutning. Dessa mål presenteras i form av en prototyp samt en prisoffert från underleverantören. Det här projektet har följt den generella produktutvecklingsprocessen där ett behov identifierades vilket var att utveckla slanganslutningen. Därefter togs idéer fram till att tillfredsställa behovet. Idéerna kunde förverkligas genom en fördjupade förståelse i tillverkningsprocessen samt användandet av CAD och simuleringar till att skapa en prototyp. Projektet resulterade i att projektmålen uppfylldes genom att en prisoffert gavs av underleverantören med en prisminskning på ca 35% till slanganslutningen. Det vidareutvecklade konceptet kunde även enligt teorin och prototypen som skapades avlasta slangen genom att slanganslutningen samarbetar i den riktning som slangen dras åt. / This report presents a master thesis within the subject product development in Royal Institute of Technology college. This work was on behalf of Weda AB which manufactures underwater cleaning solutions where existing hose connection between the robot and hose would be developed. The goal with this project was to develop the hose connection so it would relieve the hose, and also be constructed cheaper than the original hose connection. These goals are presented in a terms of a prototype and a price quote from the subcontractor. This project has followed the general product development process where a need was identified to develop the existing hose connection. Ideas were generated to satisfy the need. The ideas were executed by a deeper understandning of the manufacturing process and the using of the CAD and simulation to create a prototype. The project resulted in satisfying the project goals by a price quote given by the subcontractor with a price reduction of 35% by the hose connection. The further developed concept could also by theory and the prototype that was created offload the hose with the hose connection which cooperates in the same direction the hose is being pulled at.

No description available.

Air intake system (AIS) plays an important role on affecting the performance of the engine and the vehicle. The design and optimization of the structures and materials of AIS contributes to producing a quality reliable system, reducing noise, cost and weight at the same time, which are significant to improve the performance of engine and vehicle. Fresh air hoses/pipes are intended to transport, in air cleaner purified, air from the air cleaner to the throttle fitted on the inlet manifold or to the compressor fitted to the exhaust manifold. Air cleaner box is responsible for filtering out the dust and impurities in the air. The charge air pipes are intended to transport purified compressed air from the compressor to the charge air cooler and then to the throttle fitted on the inlet pipe. For the air cleaner box optimization, through the benchmarking and the innovation ideas from the daily life, two alternative optimized designs were introduced to reduce the cost and weight. The first is four clips connectors and the other is spring clamps. For the hose clamps, another innovation design was introduced to replace the previous hose clamps, which is called friction connector on the inner side of the bellow hose, the outer side of the air cleaner box lid and the clean side duct. For the material of the charge air ducts, TPEE was selected to replace the previous EACM rubber hoses. Further tests and prototypes should be conducted and produced to verify the effect of the optimization.

This thesis focuses on applying one of the rapidly growing non-deterministic optimization algorithms, the ant colony algorithm, for simulating automatic hose/pipe routing with several conflicting objectives. Within the thesis, methods have been developed and applied to single objective hose routing, multi-objective hose routing and multi-hose routing. The use of simulation and optimization in engineering design has been widely applied in all fields of engineering as the computational capabilities of computers has increased and improved. As a result of this, the application of non-deterministic optimization techniques such as genetic algorithms, simulated annealing algorithms, ant colony algorithms, etc. has increased dramatically resulting in vast improvements in the design process. Initially, two versions of ant colony algorithms have been developed based on, respectively, a random network and a grid network for a single objective (minimizing the length of the hoses) and avoiding obstacles in the CAD model. While applying ant colony algorithms for the simulation of hose routing, two modifications have been proposed for reducing the size of the search space and avoiding the stagnation problem. Hose routing problems often consist of several conflicting or trade-off objectives. In classical approaches, in many cases, multiple objectives are aggregated into one single objective function and optimization is then treated as a single-objective optimization problem. In this thesis two versions of ant colony algorithms are presented for multihose routing with two conflicting objectives: minimizing the total length of the hoses and maximizing the total shared length (bundle length). In this case the two objectives are aggregated into a single objective. The current state-of-the-art approach for handling multi-objective design problems is to employ the concept of Pareto optimality. Within this thesis a new Pareto-based general purpose ant colony algorithm (PSACO) is proposed and applied to a multi-objective hose routing problem that consists of the following objectives: total length of the hoses between the start and the end locations, number of bends, and angles of bends. The proposed method is capable of handling any number of objectives and uses a single pheromone matrix for all the objectives. The domination concept is used for updating the pheromone matrix. Among the currently available multi-objective ant colony optimization (MOACO) algorithms, P-ACO generates very good solutions in the central part of the Pareto front and hence the proposed algorithm is compared with P-ACO. A new term is added to the random proportional rule of both of the algorithms (PSACO and P-ACO) to attract ants towards edges that make angles close to the pre-specified angles of bends. A refinement algorithm is also suggested for searching an acceptable solution after the completion of searching the entire search space. For all of the simulations, the STL format (tessellated format) for the obstacles is used in the algorithm instead of the original shapes of the obstacles. This STL format is passed to the C++ library RAPID for collision detection. As a result of using this format, the algorithms can handle freeform obstacles and the algorithms are not restricted to a particular software package.

A natureza das ligações de hidrogênio e a influência destas interações na estrutura eletrônica de complexos neutros, catiônicos, aniônicos e radicalares foi estudada utilizando-se análises geométricas, energéticas, eletrônicas e topológicas. Inicialmente, verificaram-se alterações na aromaticidade do cátion pirílio após a complexação com uma a três moléculas de água. Tais complexos foram ainda estudados em meio reacional com constante dielétrica igual a da água com o emprego do modelo PCM (Polarizable Continuum Model). Adicionalmente, os efeitos da hidroxilação na estrutura eletrônica dos cátions benzopirílio e flavílio foram considerados. Posteriormente, analisaram-se os efeitos das fortes ligações de hidrogênio na ressonância do grupo carboxila em complexos formados entre o radical hidroperoxil e os ácidos fórmico, acético e trifluoroacético. Como extensão desse trabalho, estudos envolvendo complexos obtidos com e sem restrições na otimização de geometria possibilitaram obter informações a respeito da ressonância dos grupos carboxila e carboxilato quando o fluoreto de hidrogênio interage linear ou perpendicularmente com todos os átomos do ácido fórmico e do ânion formiato. O desenvolvimento das atividades supracitadas compreendeu a análise da função de onda pelos métodos NBO (Natural Bond Orbital), NSA (Natural Steric Analysis), NRT (Natural Resonance Theory) e AIM (Atoms in Molecules). As alterações em parâmetros geométricos e nas cargas atômicas foram consideradas. Uma análise energética foi realizada com o emprego do método de decomposição de energia proposto por Xantheas. As freqüências vibracionais e a intensidade das bandas do estiramento do grupo X-H, doador da ligação de hidrogênio, foram analisadas. As densidades de spin para os complexos radicalares também foram obtidas. A influência das ligações de hidrogênio e o efeito do substituinte na aromaticidade dos cátions foram verificados com o emprego dos métodos e índices NICS (Nucleus Independent Chemical Shifts), HOMA (Harmonic Oscillator Model of Aromaticity), HOSE (Harmonic Oscillator Stabilization Energy) e PDI (para-Delocalization Index). Os cálculos foram efetuados com os modelos B3LYP/6-31+G(d,p), B3LYP/6-311++G(3df,3pd) e UB3LYP/6-311++G(3df,3pd). Ocasionalmente, outras funções de base (EPR-III e cc-pVDZ), assim como o método MP2, foram utilizados para testar a confiabilidade dos resultados obtidos. As interações intermoleculares pouco alteraram a estrutura eletrônica e a aromaticidade do cátion pirílio. Analogamente, a substituição de um átomo de hidrogênio por um grupo hidroxila em diversas posições dos cátions benzopirílio e flavílio também não provocou modificações muito significativas na estrutura eletrônica desses cátions, embora tenha se verificado uma dependência da aromaticidade com a posição da hidroxila. Por outro lado, a distorção geométrica associada às ligações de hidrogênio foram responsáveis pelo incremento ou diminuição da ressonância do grupo carboxila nos ácidos fórmico, acético, trifluoroacético e do grupo carboxilato no ânion formiato. Os efeitos dos grupos doador e sacador de elétrons na estabilização dos complexos radicalares foram evidenciados. Adicionalmente, pode-se atribuir um caráter covalente parcial em algumas ligações de hidrogênio. / The nature of hydrogen bonds and their influence on electronic structure of neutral, cationic, anionic, and radical complexes was studied by using geometric, energetic, electronic, and topological analysis. The changes in aromaticity of the pyrylium cation upon complexation with one up to three water molecules were investigated. The PCM (Polarizable Continuum Model) model was employed to study the pyrylium-water complexes in a water reaction medium. In addition, the effects of hydroxylation on electronic structure of the benzopyrylium and flavilium cations were also considered. In addition, the effects of strong hydrogen bonds on carboxyl group resonance in the complexes formed between the hydroperoxyl radical and formic, acetic, and trifluoroacetic acids were analyzed. In extension of this work, studies including complexes, obtained with and without geometric restrictions, provided information about the resonance of the carboxyl and carboxylate groups when the hydrogen fluoride interacts, linear or perpendicularly, with all atoms of formic acid and formate anion. The analysis of the wavefunction by using NBO (Natural Bond Orbital), NSA (Natural Steric Analysis), NRT (Natural Resonance Theory), and AIM (Atoms in Molecules) methods was necessary to the development of the above mentioned activities. The changes in geometric parameters and atomic charges were also considered. An energetic analysis of complexes was done with the energy decomposition method proposed by Xantheas. The vibrational frequencies and the intensity of the X-H (hydrogen bond donor group) stretching bands were studied. The spin densities for the radical complexes were also obtained. The Nucleus Independent Chemical Shifts (NICS), Harmonic Oscillator Model of Aromaticity (HOMA), HOSE (Harmonic Oscillator Stabilization Energy), and PDI (para-Delocalization Index) aromaticity criteria were employed to verify the hydrogen bond influence and the effect of hydroxylation in the aromaticity of the cations. The calculations were carried out by using B3LYP/6-31+G(d,p), B3LYP/6-311++G(3df,3pd), and UB3LYP/6-311++G(3df,3pd) models. Occasionally, other basis set (EPR-III and cc-pVDZ), as well as the MP2 method, were applied to test the accuracy of the results. The intermolecular interactions lead to small alterations in the electronic structure and aromaticity of pyrylium cation. Similarly, the substitution at different positions of the benzopyrylium and flavilium cations by a hydroxyl group does not cause significant changes in the electronic structure of these cations. However, a dependence of the hydroxyl group position on aromaticity was observed. On the other hand, for formic, acetic, trifluoroacetic acids, as well as for the formate anion, the resonance of the carboxyl and carboxylate groups is affected not only by the geometric distortions but also by the hydrogen bonds. The effects of the electron-donating and electron-withdrawing groups in the stabilization of radical complexes were characterized. Furthermore, a partial covalent character can be attributed to some hydrogen bonds.

A natureza das ligações de hidrogênio e a influência destas interações na estrutura eletrônica de complexos neutros, catiônicos, aniônicos e radicalares foi estudada utilizando-se análises geométricas, energéticas, eletrônicas e topológicas. Inicialmente, verificaram-se alterações na aromaticidade do cátion pirílio após a complexação com uma a três moléculas de água. Tais complexos foram ainda estudados em meio reacional com constante dielétrica igual a da água com o emprego do modelo PCM (Polarizable Continuum Model). Adicionalmente, os efeitos da hidroxilação na estrutura eletrônica dos cátions benzopirílio e flavílio foram considerados. Posteriormente, analisaram-se os efeitos das fortes ligações de hidrogênio na ressonância do grupo carboxila em complexos formados entre o radical hidroperoxil e os ácidos fórmico, acético e trifluoroacético. Como extensão desse trabalho, estudos envolvendo complexos obtidos com e sem restrições na otimização de geometria possibilitaram obter informações a respeito da ressonância dos grupos carboxila e carboxilato quando o fluoreto de hidrogênio interage linear ou perpendicularmente com todos os átomos do ácido fórmico e do ânion formiato. O desenvolvimento das atividades supracitadas compreendeu a análise da função de onda pelos métodos NBO (Natural Bond Orbital), NSA (Natural Steric Analysis), NRT (Natural Resonance Theory) e AIM (Atoms in Molecules). As alterações em parâmetros geométricos e nas cargas atômicas foram consideradas. Uma análise energética foi realizada com o emprego do método de decomposição de energia proposto por Xantheas. As freqüências vibracionais e a intensidade das bandas do estiramento do grupo X-H, doador da ligação de hidrogênio, foram analisadas. As densidades de spin para os complexos radicalares também foram obtidas. A influência das ligações de hidrogênio e o efeito do substituinte na aromaticidade dos cátions foram verificados com o emprego dos métodos e índices NICS (Nucleus Independent Chemical Shifts), HOMA (Harmonic Oscillator Model of Aromaticity), HOSE (Harmonic Oscillator Stabilization Energy) e PDI (para-Delocalization Index). Os cálculos foram efetuados com os modelos B3LYP/6-31+G(d,p), B3LYP/6-311++G(3df,3pd) e UB3LYP/6-311++G(3df,3pd). Ocasionalmente, outras funções de base (EPR-III e cc-pVDZ), assim como o método MP2, foram utilizados para testar a confiabilidade dos resultados obtidos. As interações intermoleculares pouco alteraram a estrutura eletrônica e a aromaticidade do cátion pirílio. Analogamente, a substituição de um átomo de hidrogênio por um grupo hidroxila em diversas posições dos cátions benzopirílio e flavílio também não provocou modificações muito significativas na estrutura eletrônica desses cátions, embora tenha se verificado uma dependência da aromaticidade com a posição da hidroxila. Por outro lado, a distorção geométrica associada às ligações de hidrogênio foram responsáveis pelo incremento ou diminuição da ressonância do grupo carboxila nos ácidos fórmico, acético, trifluoroacético e do grupo carboxilato no ânion formiato. Os efeitos dos grupos doador e sacador de elétrons na estabilização dos complexos radicalares foram evidenciados. Adicionalmente, pode-se atribuir um caráter covalente parcial em algumas ligações de hidrogênio. / The nature of hydrogen bonds and their influence on electronic structure of neutral, cationic, anionic, and radical complexes was studied by using geometric, energetic, electronic, and topological analysis. The changes in aromaticity of the pyrylium cation upon complexation with one up to three water molecules were investigated. The PCM (Polarizable Continuum Model) model was employed to study the pyrylium-water complexes in a water reaction medium. In addition, the effects of hydroxylation on electronic structure of the benzopyrylium and flavilium cations were also considered. In addition, the effects of strong hydrogen bonds on carboxyl group resonance in the complexes formed between the hydroperoxyl radical and formic, acetic, and trifluoroacetic acids were analyzed. In extension of this work, studies including complexes, obtained with and without geometric restrictions, provided information about the resonance of the carboxyl and carboxylate groups when the hydrogen fluoride interacts, linear or perpendicularly, with all atoms of formic acid and formate anion. The analysis of the wavefunction by using NBO (Natural Bond Orbital), NSA (Natural Steric Analysis), NRT (Natural Resonance Theory), and AIM (Atoms in Molecules) methods was necessary to the development of the above mentioned activities. The changes in geometric parameters and atomic charges were also considered. An energetic analysis of complexes was done with the energy decomposition method proposed by Xantheas. The vibrational frequencies and the intensity of the X-H (hydrogen bond donor group) stretching bands were studied. The spin densities for the radical complexes were also obtained. The Nucleus Independent Chemical Shifts (NICS), Harmonic Oscillator Model of Aromaticity (HOMA), HOSE (Harmonic Oscillator Stabilization Energy), and PDI (para-Delocalization Index) aromaticity criteria were employed to verify the hydrogen bond influence and the effect of hydroxylation in the aromaticity of the cations. The calculations were carried out by using B3LYP/6-31+G(d,p), B3LYP/6-311++G(3df,3pd), and UB3LYP/6-311++G(3df,3pd) models. Occasionally, other basis set (EPR-III and cc-pVDZ), as well as the MP2 method, were applied to test the accuracy of the results. The intermolecular interactions lead to small alterations in the electronic structure and aromaticity of pyrylium cation. Similarly, the substitution at different positions of the benzopyrylium and flavilium cations by a hydroxyl group does not cause significant changes in the electronic structure of these cations. However, a dependence of the hydroxyl group position on aromaticity was observed. On the other hand, for formic, acetic, trifluoroacetic acids, as well as for the formate anion, the resonance of the carboxyl and carboxylate groups is affected not only by the geometric distortions but also by the hydrogen bonds. The effects of the electron-donating and electron-withdrawing groups in the stabilization of radical complexes were characterized. Furthermore, a partial covalent character can be attributed to some hydrogen bonds.

Resumo: O estudo teve por objetivo determinar a prevalência da brucelose bovina entre fornecedores de leite de um laticínio situado no Município de Itirapuã, Estado de São Paulo, analisar fatores de risco eventualmente associados à ocorrência de brucelose nos rebanhos estudados e analisar o desempenho de testes sorológicos para detectar a infecção. De uma população de 942 bovinos adultos distribuídos em 55 rebanhos, situados nos municípios de Itirapuã e de Patrocínio Paulista, foi obtida uma amostra voluntária composta por 813 animais, distribuídos em 37 rebanhos cujos proprietários aceitaram participar do estudo. Foi aplicado um questionário, para a obtenção de informações sobre fatores que pudessem estar associados às taxas de prevalência. Foram colhidas amostras de soro sanguíneo de todos animais, as quais foram submetidas ao teste do antígeno acidificado tamponado (AAT), e as amostras positivas nesse teste foram submetidas à reação de fixação de complemento (RFC). Foram obtidas amostras de leite do conjunto de cada rebanho participante do estudo, que foram examinadas pelo teste do anel do leite (TAL). Das 813 amostras de soro sanguíneo colhidas, 26 (3,2%) resultaram positivas na aplicação em série dos testes de triagem (AAT) e confirmatório (RFC), e das 37 propriedades estudadas, 12 (32,4%) apresentaram pelo menos um animal positivo. Os fatores que se mostraram associados à ocorrência de brucelose foram número de animais no rebanho, não utilização da vacina B19 e compra frequente de animais. Não se observou boa concordância entre o TAL, que apontou resultado positivo em quatro (10,8%) dos 37 rebanhos, e os testes sorológicos individuais na detecção de rebanhos infectados / Abstract:The aim of this investigation was to verify the prevalence of bovine brucellosis among milk suppliers of a dairy industry located in the municipality of Itirapuã, state of São Paulo, Brazil, analyze risk factors eventually associated with the occurrence of brucellosis among the herds involved in the study, and compare the performance of serological tests in detecting infected herds. From a population of 942 adult cattle in 55 herds, in the municipalities of Itirapuã and Patrocínio Paulista, a voluntary sample of 813 animals was obtained in 37 herds whose owners agreed in participating in the study. A questionnaire about risk factors that could be associated to the prevalence rates was applied. Serum samples of all the 813 animals were collected and tested by the rose Bengal plate test (RBPT); positive samples were then tested by the complement fixation test (CFT). Milk samples were taken from each can at the industry and tested by the milk ring test (MRT). Of the 813 serum samples, 26 (3.2) tested positive in the serial application of RBPT and CFT, and of the 37 herds, 12 (32.4%) had at least one positive animal. Factors that showed association with the prevalence rate were number of animals in the herd, lack of vaccination with strain 19 and frequent introduction of animals. The agreement between individual serological tests and MRT to detect infected herds was not good, since MRT showed positive results in only four (10.8%) of the 37 herds / Orientador: Luis Antônio Mathias / Coorientador: Iucif Abraão Nascif Junior / Banca: Ângela Cleusa de Fátima Banzatto de Carvalho / Banca: Fernanda Senter Magajevski / Mestre

Made available in DSpace on 2014-06-11T19:27:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-10-07Bitstream added on 2014-06-13T19:55:40Z : No. of bitstreams: 1 medeiros_mab_me_jabo.pdf: 498854 bytes, checksum: 73074b86ac0db45184c33210013d1ef4 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O estudo teve por objetivo determinar a prevalência da brucelose bovina entre fornecedores de leite de um laticínio situado no Município de Itirapuã, Estado de São Paulo, analisar fatores de risco eventualmente associados à ocorrência de brucelose nos rebanhos estudados e analisar o desempenho de testes sorológicos para detectar a infecção. De uma população de 942 bovinos adultos distribuídos em 55 rebanhos, situados nos municípios de Itirapuã e de Patrocínio Paulista, foi obtida uma amostra voluntária composta por 813 animais, distribuídos em 37 rebanhos cujos proprietários aceitaram participar do estudo. Foi aplicado um questionário, para a obtenção de informações sobre fatores que pudessem estar associados às taxas de prevalência. Foram colhidas amostras de soro sanguíneo de todos animais, as quais foram submetidas ao teste do antígeno acidificado tamponado (AAT), e as amostras positivas nesse teste foram submetidas à reação de fixação de complemento (RFC). Foram obtidas amostras de leite do conjunto de cada rebanho participante do estudo, que foram examinadas pelo teste do anel do leite (TAL). Das 813 amostras de soro sanguíneo colhidas, 26 (3,2%) resultaram positivas na aplicação em série dos testes de triagem (AAT) e confirmatório (RFC), e das 37 propriedades estudadas, 12 (32,4%) apresentaram pelo menos um animal positivo. Os fatores que se mostraram associados à ocorrência de brucelose foram número de animais no rebanho, não utilização da vacina B19 e compra frequente de animais. Não se observou boa concordância entre o TAL, que apontou resultado positivo em quatro (10,8%) dos 37 rebanhos, e os testes sorológicos individuais na detecção de rebanhos infectados / The aim of this investigation was to verify the prevalence of bovine brucellosis among milk suppliers of a dairy industry located in the municipality of Itirapuã, state of São Paulo, Brazil, analyze risk factors eventually associated with the occurrence of brucellosis among the herds involved in the study, and compare the performance of serological tests in detecting infected herds. From a population of 942 adult cattle in 55 herds, in the municipalities of Itirapuã and Patrocínio Paulista, a voluntary sample of 813 animals was obtained in 37 herds whose owners agreed in participating in the study. A questionnaire about risk factors that could be associated to the prevalence rates was applied. Serum samples of all the 813 animals were collected and tested by the rose Bengal plate test (RBPT); positive samples were then tested by the complement fixation test (CFT). Milk samples were taken from each can at the industry and tested by the milk ring test (MRT). Of the 813 serum samples, 26 (3.2) tested positive in the serial application of RBPT and CFT, and of the 37 herds, 12 (32.4%) had at least one positive animal. Factors that showed association with the prevalence rate were number of animals in the herd, lack of vaccination with strain 19 and frequent introduction of animals. The agreement between individual serological tests and MRT to detect infected herds was not good, since MRT showed positive results in only four (10.8%) of the 37 herds