Made available in DSpace on 2018-08-01T21:36:25Z (GMT). No. of bitstreams: 1 tese_6378_Dissertação Roque Luz 2013 (1).pdf: 622291 bytes, checksum: 092d430b71a23ee53076930335007ad5 (MD5) Previous issue date: 2013-04-26 / Entender os mecanismos da percepção subjetiva de esforço (PSE) sempre foi um desafio por se tratar de um objeto de estudo subjetivo. Desde a sua concepção até os dias atuais muitos estudos buscam entender as correlações da PSE com diversos mecanismos fisiológicos. Pouco se sabe sobre as possíveis alterações que a PSE possa ter após período de treinamento aeróbico. Essa carência de estudos sobre a correlação da PSE com a frequência cardíaca (FC) no que diz respeito ao comportamento após período de treinamento motivou a realização deste estudo. O objetivo principal foi comparar o comportamento da PSE e da FC antes e após o treinamento em cada grupo e entre os grupos, além da correlação entre a PSE e FC. O presente estudo analisou o comportamento da PSE e FC durante teste cardiopulmonar de exercício em indivíduos submetidos a três diferentes programas de treinamento aeróbico por um período de 13 semanas ininterruptas. Os grupos foram submetidos a uma periodização ondulatória, crescente ou escalonada. As diferenças nas distribuições de intensidade estavam relacionadas à presença ou não de período com intensidade reduzida e ao formato de incremento da intensidade dos estímulos. Na análise estatística foi empregado o teste de Wilcoxon para avaliar a PSE antes e depois dentro do grupo e o teste de Mann-Whitney para a comparação da PSE entre os grupos. Para a análise do comportamento da FC empregou-se o teste t de Student pareado para cada grupo e o teste t de Student para amostras independentes na comparação entre os grupos. A correlação entre a PSE e FC foi obtida através da correlação de Pearson. O nível de significância adotado foi o de p<0,05. Constatou-se que somente o grupo escalonado apresentou diferenças no comportamento da PSE quando comparamos os testes inicial e final. O comportamento da FC foi alterado em todos os grupos apresentando redução dos valores em todos os estágios, com exceção de um aumento de valores, somente no último estágio do grupo ondulatório. Quando comparados os valores de PSE e FC entre os grupos as diferenças ocorreram pontualmente em alguns estágios sem a possibilidade de afirmar que existe relação direta entre os tipos de periodização e as variáveis estudadas. A correlação entre a PSE e FC ocorreu de forma positiva com valores de correlação ~0,72. Os dados sugerem que o comportamento da PSE pode sofrer alguma alteração após período de treinamento aeróbico, especificamente quando utilizado o método escalonado para a progressão de intensidades.

Denna rapport genomgår ett produktutvecklingsarbete för Husqvarna genom ett examensarbete på Jönköpings Tekniska Högskola. Projektet var att integrera ett datainsamlingssytem (H-DAS), Akustisk emissions sensor (AE-sensor) samt en display in i motorsågen 540 iXP. Syftet var att utveckla designlösningar för att kunna integrera mätsystem i motorsågen, systemet ska även klara av motorsågens förhållande samt tilltala Husqvarnas designspråk.   För att veta hur de olika designlösningarna ska se ut, samt var mätsystemen ska placeras, monterades motorsågen isär. Då en display ska integreras synlig för användaren behövdes en bättre bild på vad användaren har för krav på placering av display och en förstudie gjordes på QA-kontoret på Husqvarna. Efter detta kunde en kravspecifikation skapas för de olika designlösningarna.  De krav som finns för arbetet är olika i delområdena som arbetet berör. AE-sensorn har ett krav om placeringen då sensors kräver kontakt med svärdet. H-DAS systemet ska integreras med hjälp av en låda, kravet på lådan är att den skall ha plats för de olika komponenterna som finns i datorinsamlingssystemet (H-DAS). Displayen ska integreras på användargränssnittet, då displayen ska göras synlig är kravet att användaren ser displayen vid användningen.  Resultatet som framkom var att AE-sensorn fick en design som passar de olika krav som den behövde uppfylla, samt att designen blev anpassad för applikationen. Lådan fick lite fler problem genom att utrymmet som hade blivit utvalt var inte tillräckligt stort för alla interna delar, men efter en diskussion med Husqvarna så blev det att endast de nödvändigaste komponenterna i H-DAS systemet blev kvar. Användargränssnittet fick en ny design så det blev möjligt att integrera displayen, utan designändringar hade inte konceptet fått plats på motorsågen. Det slutgiltiga resultatet var att systemet gick att integrera och att alla de frågeställningar som blev ställda blev besvarade. / This rapport works through a product development assignment for Husqvarna through a thesis done at Jönköping’s University. The project was to integrate a data collection system (H-DAS), an acoustic emission sensor (AE-sensor), and a display into the iXP chainsaw. The purpose was to develop a design solution to integrate measurement systems into the chainsaw while also meeting the chainsaw’s requirements and adhering to Husqvarna’s design language. To determine the appearance of the different design solutions and the placement of the measurement systems, the chainsaw was disassembled. Since a display was to be integrated and to be visible to the user, a better understanding of the user’s requirements regarding the display was needed. A preliminary study was conducted at Husqvarna’s QA office. Based on this, a requirement specification could be created for the different design solutions. The requirements for the project vary in the different areas it encompasses. The AE-sensor has a requirement regarding its placement because it needs to have contact with the sword of the chainsaw. The H-DAS system is to be integrated using a box, and one requirement for the box is that it should accommodate the various components of the data collection system (H-DAS). The display should be integrated into the user interface, and the requirement is that the user can see the display during operation. The resulting design for the AE-sensor met the necessary requirements and was adapted for the application. The box encountered some issues as the chosen space was not sufficient for all the internal components. However, after discussing it with Husqvarna, it was decided to retain only the essential components of the H-DAS system. The user interface underwent a redesign to allow for successful integration of the display. Without the design changes the concept would not have fit on the chainsaw. The result was that the system could be successfully integrated, and all the questions that were asked were answered.

Pneumatic drives are an integral part of many machinery, with high demands on their reliability. Unfortunately, they sometimes fail, either due to improper production or assembly at the factory or by gradual degradation of moving parts and sealing elements during operation. Current diagnostic methods do not allow localization or identification of the type of damage and do not allow the operator to make a qualified decision. This work deals with the use of acoustic emission for these purposes. On PB type cylinders manufactured by Poličské strojírny a.s., a methodology is introduced which leads to the direct identification or at least localization of selected defects. By implementing this methodology in the final inspection of the production plant, the percentage of exposed pieces of waste will be increased, thus preventing accidents of these faulty pieces during operation.

This Master’s thesis is concerned with project and construction of several versions of mounting device for verification of acoustic emission sensors parameters, selection of optimal solution and its testing. In addition is described the measurement procedure, that allows detailed analysis and evaluation of the data focused on comparing of parameters of acoustic emission sensors.

The aim of the diploma thesis is to study fatigue properties of EN AW-2618A aluminium alloy produced by selective laser melting (SLM). S-N diagrams of reference alloy and SLM material depending on manufacturing conditions were constructed. Reference alloy had the same chemical composition as the SLM material, but it was made by traditional technology (by extruding). While testing, acoustic emission (AE) and resonant frequency of loading was monitored. Fractographic analyses of fracture surfaces were performed. It was found, that SLM material has significantly worse fatigue performance. Fatigue properties are strongly dependent on SLM process parameters settings and precise observance of procedure. The most significant differences in cyclic degradation were found in the length of the stages of fatigue. The more homogeneous the material is, the longer the nucleation stage compared to the total lifetime is. The main source of AE in case of the reference material is plastic deformation on the tip of the crack. For SLM testing, stronger acoustic activity was recorded, because brittle fracture of the material between discontinuities, which is stronger AE source, is more frequent.

Acoustic emissions are small vibration pulses, elastic waves, emitted from damage processes such as crack growth inside a material. Acoustic emission (AE) is also the name of the test method in which theses emissions are recorded and analysed and the method is used in materials research and the testing and inspection of structures. At Scania, a large manufacturer of trucks and buses, previous attempts to implement this technique has been unsuccessful due to the fact that the hydraulic rigs in which the material typically is tested, produce a high background noise level, that covers the interesting emissions from the material.In this thesis two materials, a grey iron and a carbon fiber reinforced polymer were tested in a hydraulic rig at Scania. Since the material signal was buried in the noise, the entire waveform was recorded, which is an unusual approach, since it generates large amounts of data. It was shown that using frequency analysis, it is possible to extract the material emissions in spite of the hydraulic noise. That fact makes it possible to follow the internal processes of the material leading up to failure, which means new interesting opportunities in materials testing at Scania. / Akustisk emission är små elastiska vågor som bland annat kommer från processer i ett material, såsom spricktillväxt. Akustisk emission (AE) är namnet på den testmetod där dessa vibrationer registreras och analyseras. Metoden används i materialprovning och för att testa och inspektera komponenter, såsom tryckkärl. På Scania, en stor tillverkare av lastbilar och bussar, har tidigare undersökningar för att implementera denna teknik på utmattning inte lyckats. Anledningen ligger i att de hydrauliska riggarna som testningen vanligtvis sker i, typiskt sett genererar ett bakgrundsljud som skymmer den intressanta signalen från materialet. I detta examensarbete testades två typer av material, gråjärn och en kolfiberarmerad komposit, i en hydraulisk rigg på Scania. Eftersom de akustiska emissionerna från materialet gömdes i bakgrunden användes metoden att spara ner hela vågformen för signalen, vilket är ovanligt eftersom detta innebär att mycket stora mängder data måste sparas. Det visade sig genom frekvensanalys vara möjligt att extrahera de akustiska emissionerna från materialet, trots det hydrauliska bruset. Det faktum att det är möjligt att följa de processerna inuti materialet, som föregår brottet, öppnar upp nya intressanta möjligheter för materialprovning på Scania.

The aim of the doctoral thesis is the problem of the primary calibration of acoustic emission sensor. In the introductory chapters, there are the results from the study of literature in field of AE and primary calibration of AE sensor summarized. The practical part of the thesis is aimed on realization of the primary calibration of AE sensors by different methods. The standardized methods of step function calibration and reciprocity calibration were practically realized as a part of the research on the same aparature. The method of reciprocity calibration with wideband excitation was practically realized too. The comparison between results from each used method was realized and the influences of the different sources of uncertainty and the different configuration of the calibration aparature on the step function calibration and the reciprocity calibration were determined. The uncertainties were determined for each realized methods. The recommendations for the calibration by the different methods on the available calibration aparature were presented. All the proceses of the reciprocity primary calibration was automated by the programmed software and the channel switcher. The UT 1000 (s.n. 169) by Physical Acoustic Corporation was used as the calibrated sensor for the comparison of the results of the calibrations.

This study is an optimization approach to the rectilinear interdiction problem by locating a line barrier. Interdiction problems study the eect of a limited disruption action on operations of a system. Network interdiction problems, where nodes and arcs of the network are susceptible to disruption actions, are extensively studied in the operations research literature. In this study, we consider a set of sink points on the plane that are being served by source points and our aim is to study the eect of locating a line barrier on the plane (as a disruption action) such that the total shortest distance between sink and source points is maximized. We compute the shortest distances after disruption using visibility concept and utilizing properties of our problem. The amount of disruption is limited by imposing constraints on the length of the barrier and also the total number of disrupted points. The suggested solution approaches are based on mixed-integer programming and a polynomial-time algorithm.

The two-phase gas/liquid flow phenomenon can be encountered over a range of gas and liquid flow rates in the chemical engineering industry, particularly in oil and gas production transportation pipelines. Monitoring and measurement of their characteristics, such as the gas void fraction, are necessary to minimise the disruption of downstream process facilities. Thus, over the last decade, the investigation, development and use of multiphase flow metering system have been a major focus for the industry worldwide. However, these meters suffer from several limitations in some flow conditions such as Slug flow regime. This research presents experimental results correlating Acoustic Emission measurements with Gas Void Fraction (GVF) in a two-phase air / water flow. A unique experimental facility was modified to accommodate an investigation into the applicability of the Acoustic Emission (AE) technology in monitoring two-phase gas\liquid flow. The testing facility allowed for investigations over a range of superficial liquid velocities (0.3 to 2.0 ms-1) and superficial gas velocities (0.2 to 1.4 ms-1). The influence of several variables such as temperature, viscosity and surface roughness were also investigated. Measurements of AE for varying gas void fractions were compared to conductive probe measurements and results showed a direct correlation between the AE energy and the gas void fraction. It is concluded that the GVF can be determined by measurement of Acoustic Emission and this forms the major contribution of this thesis.

In this study, we use the swelling characteristics of bentonite to discussion about the performance of bentonite mortar anti-seepage and the performance of resistance to sulfate. And add the AE water-reducing to improve its workability. To compare with different rate of bentonite added at different ratio of AE water-reducing in the condition of Standard Test for Flow Table. We planning in different water-cement ratio (0.445,0.485,0.550) to test for its fresh properties and hardened properties, and discussion the effect by AE water-reducing on the marine engineering. According to this study, adding bentonite will make the flow value dropped, and affecting the workability. Because of the positive ion exchange properties between bentonite and water will make it a high volume exchange rate, it means that absorption is high, so when the mixing time, the bentonite will form clumps, in this study, we add the AE water-reducing to improve. After we add AE water-reducing, the absorption, compressive strength are increase, but we still had to pay attention to the ratio between bentonite and AE water-reducing, the strength of structure perhaps decrease if added too much bentonite. This study can get the best positive effect when added ratio of 0.25% of bentonite to replaced cement.