Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Acoustical noises are known as pollution sources that cause adverse effects in human life. Considerable investigations have been done to development of the new technologies in Active Noise Control. This work presents and experimentally analyses algorithms of Active Noise Control in Ducts presented in literature, including Feedforward algorithms, Feedback algorithms and Hybrid algorithms that uses both concepts. The identification of secondary path and feedback path is presented and solutions are discussed. In this way, methods of off-line and on-line modeling are presented. A short introduction about acoustics in ducts is presented and some effects that the acoustical noise can cause in human being are also discussed. Problems about the sensors and actuators displacement in the duct system, causality and signal conditioning are also argued here. An introduction about Digital Signal Processors (DSPs) e some particularities found in the development of this works are presented. In order to evaluate the control algorithms performance, an experimental acoustic duct using a standard PVC water pipe was built, where those algorithms were implemented in a DSP platform TMS320LF240A from Texas Instruments®. An analysis is done about the difficulty and recourses used for which algorithm implemented. This work ends presenting and discussing the obtained results for the different control procedures studied and pointing to some future works. / Ruídos acústicos são conhecidos como fontes de poluição sonora que podem causar efeitos adversos na vida humana. Para solucionar estes problemas, interesse considerável tem sido mostrado em Controle Ativo de Ruído. O intuito deste trabalho é estudar e analisar os principais algoritmos de Controle Ativo de Ruído presentes na literatura, incluindo algoritmos de malha aberta (Feedfoward) e de malha fechada (Feedback), bem como um sistema híbrido que utilize os dois conceitos. Os problemas relacionados aos caminhos secundário e de realimentação são apresentados e algumas soluções são discutidas. Neste âmbito, metodologias de modelagem off-line e online são apresentadas. Uma pequena introdução à acústica básica em dutos é apresentada e alguns efeitos que o ruído acústico pode causar ao ser humano são discutidos. Uma discussão é realizada a respeito do arranjo físico do sistema, incluindo escolha e posicionamento dos transdutores eletroacústicos. Problemas de causalidade e do condicionamento de sinais também são discutidos. Uma introdução a respeito dos Processadores Digitais de Sinais (DSPs) e algumas particularidades encontradas durante o desenvolvimento deste trabalho são apresentadas. Para validar a performance de alguns algoritmos de controle, montou-se uma bancada experimental constituída de um duto hidráulico de PVC utilizado como duto acústico, onde estes algoritmos foram implementados em linguagem C em uma plataforma DSP da Texas Instruments do tipo TMS320LF240A. Uma análise é realizada com respeito à dificuldade e recursos utilizados por cada algoritmo implementado. Resultados e discussões são apresentados com respeito à performance dos sistemas de controle. / Mestre em Engenharia Mecânica

Submitted by Daniella Sodre (daniella.sodre@ufpe.br) on 2015-04-08T12:40:55Z No. of bitstreams: 2 DISSERTAÇÃO Gabriel Fonseca.pdf: 3837074 bytes, checksum: e2c9b20882785e374170658d648ee389 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-04-08T12:40:55Z (GMT). No. of bitstreams: 2 DISSERTAÇÃO Gabriel Fonseca.pdf: 3837074 bytes, checksum: e2c9b20882785e374170658d648ee389 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2014-03-10 / Conselho Nacional de Desenvolvimento Científi co e Tecnol ógico; Coordenação de Aperfeiçoamento de Pessoal de Ní vel Superior; Financiadora de Estudos e Projetos; Fundação de Amparo a Ciência e Tecnologia do Estado de Pernambuco. / In this master thesis we study experimentally the longitudinal spin Seebeck effect (LSSE) in bilayers made of a ferromagnetic insulator (FMI) and a metallic layer (M). We also present a theoretical model based on the spin current density ⃗ Js carried by a non-equilibrium magnon distribution, generated by a thermal gradient ∇T across the thickness of the FMI. When ⃗ Js reach the FMI/M interface it is pumped towards the M layer due to conservation of the angular momentum, so, the M layer is essential for the LSSE existence. Here the FMI consists of a Yttrium Iron Garnet (YIG) lm, grown over a Gadolinium Gallium Garnet (GGG) substrate. Different metallic materials were used as the M layer i.e. Pt and Ta that have normal behavior and Py that is a ferromagnetic metal (FMM). The experimental procedure consists of systematic measurements of the electric voltage VISHE, produced by ⃗ Js through the Inverse Spin Hall Effect (ISHE) in the normal metal or (FMM) layer. In YIG/Pt measurements were done in the temperature range from 20 to 300 K. The experimental data are tted to the proposed model for the LSSE and good agreement is obtained. The results shows that the Py and Ta can be used to detect the LSSE with the ISHE. The results of this master thesis have strong interest in the area of spin caloritronics helping to the development of the eld and to raise possibilities of new spintronic devices. ----- Nesta diserta ção e estudado experimentalmente o Efeito Seebeck de Spin Longi- tudinal (LSSE), em bicamadas formadas por um isolante ferromagn etico (FMI) e um lme metalico (M). Tamb em foi desenvolvido um modelo te orico baseado na den- sidade de corrente de spin ⃗ Js que existe quando uma distribui c~ao de m agnons fora do equil brio e gerada por um gradiente t ermico ∇T aplicado na sec ção transversal do FMI. Quando ⃗ Js chega na interface FMI/M e bombeada para a camada M satis- fazendo a conserva ção do momentum angular, assim que a camada NM e essencial para ter um LSSE. Como camada FMI foi utilizada a granada de trio e ferro (YIG) crescida num substrato de (GGG). Diferentes materiais metalicos foram utilizados como camada M, sendo Pt e Ta paramagn eticos e o Py ferromagnetico. O proced- imento experimental consiste na medi c~ao sistem atica da voltagem el etrica VISHE, que e produzida por ⃗ Js por meio do efeito Hall de spin inverso (ISHE) que ocorre na camada M. As medidas em YIG/Pt foram feitas numa faixa ampla de temperatura de 20 a 300 K. Os dados experimentais são fi tados com a teoria proposta para o LSSE encontrando-se boa concordância. Nossos resultados mostram que o Py e o Ta s~ao bons candidatos para detec ção do LSSE. Esta disserta ção e de grande interesse na area da caloritrônica de spin, ajudando no desenvolvimento deste campo e na concep ção de novos dispositivos tecnol ogicos baseados na spintrônica.

e-learning, as defined to be the use of information and communications technology (ICT) for supporting the educational processes, has motivated Tanzania to apply ICT in its education system. Tanzania secondary schools in rural areas are geographically and socially isolated. Rural Tanzania secondary schools face a number of problems including ways in getting learning materials, as well as inadequacy in qualified teachers. The impact of these problems is poor performance in National Examinations. This poor performance however is highly noted in science and mathematics subjects. The problem in getting learning materials can be reduced by employing ICT in secondary school education system. This research develops an interactive e-learning management system (e-LMS) to be used by Tanzanian secondary schools. The research is aiming to support teaching and learning functions by allowing creation and storage of learning materials, making them available, easily accessed and sharable among students from different secondary schools in Tanzania in a more organized way. Tanzania has only one curriculum for all secondary schools registered under the Ministry of Education and Vocational Training (MoEVT). During development stage it will not be easy to involve all scattered Tanzanian secondary schools. The research is focusing to two selected pilot schools; Kibaha secondary school and Wali-ul-Asr girls’ seminary in Kibaha town, Pwani region. Features of the e-LMS will represent the standard form of any other secondary school registered by the MoEVT. The complete implementation of the e-LMS to these selected pilot schools will later be extended to all other secondary schools in Tanzania. The development uses Object-Oriented System Analysis and Design (OOSAD) approach along with the power of modeling as it has been emphasized by Model Driven Architecture (MDA). Unified Modeling Language (UML) is mainly used in both cases. To create an interoperable system, UML is integrated with extensible markup language (XML) during model transformation from e-LMS Platform Independent Model (PIM) to e-LMS Platform Specific Model (PSM). Development will make use of open source software. For context specific development, participatory action research methodology is adopted and the inputs are well presented in developing e-LMS. Customization of open source learning management system (LMS) platforms is employed to help generate a timely solution to e-LMS development. Finally, this thesis also considers the need for replication and mirroring of the database for the purpose of making learning materials highly available to end-users.

Tertiary institutions in South Africa are currently faced with several challenges: Student numbers are increasing, funding is not necessarily sufficient and the type of student who enters Higher Education is part of a generation which grew up with technology (Prensky, 2001). Expectations are that tertiary education institutions need to keep up with the changing environment, whilst still maintaining high standards. Interaction within the learning environment is essential, both from an academic, as well as a social point of view. Students who leave the institution need to be able to function in a working environment, with all the challenges that accompany it, as well as be academically qualified for their careers. Universities, and specifically Economics departments, are often accused of being ivory towers with no regard for the real world (Fullbrook, 2003). The design for this study is a case-study within a qualitative research design. The study focuses on the use of an LMS to aid the learning process in a blended learning environment at the department of Economics, at the University of the Free State. In this study, several tools were used to support students and add another dimension to learning economics. Data-collection instruments include a literature review, focus group meetings, semi-structured questionnaires and observations. The value of this study is that it forms a basis for lecturers in other disciplines to include aspects of blended learning in their courses. The findings of the research include the usability of the different LMS tools, students’ experiences of these tools and the effect that these tools have on their understanding and integration of economics. The rationale of this study is based on the fact that students who attend university come from a generation identified as Digital Natives (Prensy, 2001) and have certain methods of data integration. The purpose of this study is, therefore, to focus and analyse students’ experiences of using WebCT tools as an additional aid to the course. The target group for the study was the Economics firstyear, second semester, English medium of instruction students. The course runs over a full semester, with two traditional facetoface classes, as well as tutor groups. In addition to two semester tests and an examination, students had to participate in a biweekly discussion forum, based on economic events and four online, multiple choice quizzes. They also had access to class notes, additional readings, informal discussions and a forum for questions. This research makes use of a qualitative approach and a casestudy, because it studies a “…human activity embedded in the real world which can only be studied or understood in context … which exists in the here and now that merges in with its context so that precise boundaries are difficult to draw” Gillham (2000). This study falls within the Interpretivist paradigm (Burrel and Morgan). Data were collected by means of focus group meetings, informal discussions, openended questionnaires, observations and a course evaluation. In this way, students’ attitudes towards the LMS could be gauged. Three categories were identified during the data analysis and coding process. The first category relates to interaction between students and lecturers (or tutors), the second to peerinteraction and the last category refers to contentstudent interaction. The findings of this study concludes that students need interaction with lecturers, peers and content in order to make sense of what they are learning, to link the theory with realworld issues and to enhance generic skills. Lecturers should consider making use of a hybrid learning system, but must consider their specific course content before deciding which of the available tools to use. / Thesis (PhD (Curriculum Studies))--University of Pretoria, 2006. / Curriculum Studies / unrestricted

This master thesis solves the problem of estimating the quality of ECG signals. The main objective of the work is to implement a self-assessment of the quality assessment method based on the studied methods for estimating the quality of the ECG signal. The theoretical part of the thesis contains mainly the description of the electrical activity of the heart, cardiac anatomy, and physiology, electrocardiography, various types of ECG signal interference and methods describing the estimation of ECG signal quality. The practical part deals with the application of individual methods for estimating the quality of ECG signals. The SNR (signal-to-noise ratio) calculation is used to continuously estimate the quality of the ECG. Signal quality can also be judged based on statistical functions, adaptive filtering, or by analyzing independent components. The proposed method is based on the calculation of the correlation coefficient between the adaptive template and the disturbed signal. The robustness of the method was verified on artificially created ECG signals with different noise levels and then on real signals from the MIT-BIH database.

Noise emission is a major drawback of the positive displacement machine. The noise source can be divided into structure borne noise source (SBNS) and fluid borne noise source (FBNS). Passive techniques such as valve plate optimization have been used for noise reduction of axial piston machines. However, passive techniques are only effective for limited operating conditions or at least need compromises in design. In this paper, active vibration control of swash plate is investigated for vibration and noise reduction over a wide range of operating conditions as an additional method to passive noise reduction techniques. A 75cc pump has been modified for implementation of active vibration control using the swash plate. One tri-axial acceleration sensor and one angle sensor are installed on the swash plate and a high speed servovalve is used for the swash plate actuation. The multi-frequency two-weight least mean square (LMS) filter synthesizes the servovalve input signal to generate a destructive interference force which minimizes the swash plate vibration. An experimental test setup has been realized using Labview field-programmable gate array (FPGA) via cRIO. Simulation and experimental studies are conducted to investigate the possibility of active vibration control.

Today more and more courses at both universities and at the municipal adult educations (Komvux) are given as distance courses. Therefore, the need for good digital resources is ever growing, to provide the same standard of education at the distance courses as it is on the regular courses. The following study is an investigation of some of the digital resources available for both aid in information intake and subject understanding, and also on the resources available for social interactions with other students as well as teachers during the courses. The study is conducted as a systematic literature study with a thematic analysis. The resources studied are LMS, virtual classrooms, the flipped classroom model and digital textbooks and libraries. Also, the importance of adaptive digital resources as well as how digital resources are best implemented are studied. Conclusions made shows that much can be improved in the distance courses and that a combination of flipped classroom presentations together with a program for social interactions (such as Edmodo) could be a better solution. For the parts of the courses in Biology where a more in depth understanding of processes is necessary, special model building programs would be favorable. Since the possibilities for individual adaptions is very limited in distance courses it would also be advantageous with adaptive digital resources, to increase the possibilities for a student to pass the course.

Master's thesis contains basic informations about e-learning and describe it by many criteria. It also describes progress and current trends in e-learning and what is needed to create interactive study materials and courses. I analyse most important advantages and disadvantages of these courses. I designed Web-based training system (WBT) for driving school, which is implemented as a program prototype of e-learning system.

Introduction: To date cranial development has only been described by analyzing occipitofrontal circumference (OFC). More precise methods of determining head measurements have not been widely adopted. The use of additional measurements has the potential to better account for the three-dimensional structure of the head. Our aim was to put forward centile curves of such measurements for gestational age along with a compound head volume index. Methods: We created generalized additive models for location, scale, and shape of two ear-to-ear distances (EED), transfontanellar (fEED) and transvertical (vEED), from birth anthropometric data. Same was done for OFC, crown-heel length, and birth weight to allow for comparison of our models with growth charts by Voigt et al. and Fenton and Kim. Results: Growth charts and tables of LMS parameters for fEED and vEED were derived from 6,610 patients admitted to our NICU and 625 healthy term newborns. With increasing gestational age EEDs increase about half as fast compared to OFC in absolute terms, their relative growths are fairly similar. Discussion: Differences to the charts by Fenton and Kim are minute. Tape measurements, such as fEED or vEED can be added to routine anthropometry at little extra costs. These charts may be helpful for following and evaluating head sizes and growth of preterm and term infants in three dimensions.

The Education Industry is crucial to the development of societies and their economy, consequently, it is important to understand how technological advancements affect the industry and its stakeholders. Research has been made on this topic, mainly focusing on the concept and framework, implications for the Education Industry, and possible societal transformations, but few focus on the implementation and evolution of the Internet of Things (IoT) in the education industry, the Internet of Education Things (IoET), especially within higher education. Living in the Information Age, it is important to understand how things that provide access to power(as in information) are implemented and evolve. The purpose of this research is to study the IoET in the Swedish higher education reality, to provide a deeper understanding of the rapid changes in the industry, the evolution, and development of the IoET model as well as the outcomes over a ten years timeframe for the institution, by answering the research question“How did the implementation process of IoET evolve?”. The research was conducted implementing a qualitative exploratory approach, using a single case study adopting grounded theory and thematic analysis, with an interpretative approach that allowed the interviewees to voice their experiences and perspectives on the phenomenon. It was found that the past decade, especially the last five years, has meant pervading IoET transformations on multiple levels within the university, such as the teaching and learning, privacy and security, classroom environment, and energy monitoring, as well as digital connectors. These transformations were found to have strong connections to external pressure, internal pressure, regulations, centralisation, and most recently COVID-19. Each of these motivations was found to be related to the different transformations mentioned above, which also has meant different paces of transformation, and in turn different outcomes. We found that the increasing pace of these implementations has made the level of satisfaction decrease among the different stakeholder groups.