Cylindrical shells are common structures that are often used in industry, such as pipes, ducts, aircraft fuselages, rockets, submarine pressure hulls, electric motors and generators. In many applications it is desired to attenuate the sound radiated from the vibrating structure. There are both active and passive methods to achieve this purpose. However, at low frequencies passive methods are less effective and often an excessive amount of material is needed to achieve acceptable results. There have been a number of works regarding active control methods for this type of structure. In most cases a considerable number of error sensors and secondary sources are needed. However, in practice it is much preferred to have the fewest number of error sensors and control forces possible. Most methods presented have shown considerable dependence on the error sensor location. The goal of this dissertation is to develop an active noise control method that is able to attenuate the radiated sound effectively at low frequencies using only a small number of error sensors and secondary sources, and with minimal dependence on error sensor location. The Weighted Sum of Spatial Gradients control metric has been developed both theoretically and experimentally for simply supported cylindrical shells. The method has proven to be robust with respect to error sensor location. In order to quantify the performance of the control method, the radiated sound power has been chosen. In order to calculate the radiated sound power theoretically, the radiation modes have been developed for cylindrical shells. Experimentally, the radiated sound power without and with control has been measured using the ISO 3741 standard. The results show comparable, or in some cases better, performance in comparison with other known methods. Some agreement has been observed between model and experimental results. However, there are some discrepancies due to the fact that the actual cylinder does not appear to behave as an ideal simply supported cylindrical shell.

The thesis deals with the issue of measurement of frequency and its derivative (RoCoF) in simulation software. The aim of the thesis was to compare results obtained in three different pieces of software (PSS/E, PSCAD, MODES). 2 disturbances were simulated in a grid model IEEE 39 bus system and values of frequency and generator speed were assessed. The results obtained in different software are diverse. This is influenced by method of modelling of synchronous generator and algorithm of calculation of frequency. Findings are important for future investigation of power system transients in simulation software and also point to potencial incorrect assassement of frequency in protective relays.

The thesis deals with the comparison of two restoration paths in case of the black start in the MODES and PSCAD simulation programs. The aim was to compare the voltage waveforms in individual nodes and the system frequency. At the same time, simulations were compared with a real test. The route models in the MODES program were created earlier and the task was to create the same routes in the PSCAD program using the parameters available from the MODES program. The route models in the PSCAD environment included both the original and the new models of individual elements, which had to be assembled from function blocks. The results of the programs differed slightly, which was caused mainly by the differences of some elements that were used. In the thesis, all the necessary information was stated to make the simulations repeatable.

Diplomová práca analyzuje potenciálne možnosti vstupu už existujúcej slovenskej firmy na zahraničný trh. Cieľom je porovnanie možnosti expanzie firmy do členského štátu Európskej únie so štátom mimo Európskej únie a výber najvhodnejšej z nich. Poznatky z odbornej literatúry uvedené v teoretickej časti práce, predstavujú nevyhnutný základ pre výber vhodných nástrojov a analýz k vypracovaniu analytickej časti. Posledná časť práce je venovaná konkrétnym návrhom riešení, ktoré vedú k dosiahnutiu stanovených cieľov.

The aim of this study was to examine the role of distance education in providing access to quality postgraduate education in Ethiopia, using the Indira Gandhi National Open University (IGNOU) as a case study. It draws on the development of distance education and it further explores the distance education programme delivery system in Ethiopia on the postgraduate level. In addition, the study explores the policy gap between conventional and distance education in relation to international postgraduate distance education. The study, specifically, focuses on the Master of Arts in Rural Development (MARD) programme offered by IGNOU in Addis Ababa, Ethiopia, in terms of the opportunities it provides for alternative access to postgraduate education. It also explores the quality and quality assurance strategies employed in distance education. Two instruments were used to gather relevant data, namely: interviews and document analysis. The structured interviews were conducted with MARD graduates and current students at IGNOU in 2012. Other semi-structured and structured interviews were conducted with the dean and department head, programme coordinator, tutors, the institution‘s top-level managers, the course and materials dispatching officer and administrator as well as with policy-makers at the Ministry of Education (MoE). Furthermore, interviews were conducted with higher education experts and other MoE senior officials in foreign relations and those involved in cross-border private higher institutions. Senior officials from the Higher Education Relevance and Quality Agency (HERQA) were also interviewed, such as the deputy director and senior officials who are responsible for quality audit and accreditation for both private and public higher education as well as the external quality auditors. A total sample size of thirty respondents participated in the study and the respondents were purposefully selected from diverse areas. The data gathered, using a qualitative method, was analysed. The selected relevant documents for the study were also thoroughly analysed and agreed with the interview findings. The study established that distance education has the potential to contribute significantly to the provision of higher education in Ethiopia. As the main findings of the study revealed, there is recognition of the MARD programme by the participants, especially the graduates in terms of the fulfilment of certain quality elements which is largely due to the promotion they received after the completion of the programme. The MoE participants indicated an acceptance of IGNOU in terms of it increasing access to higher education, even though it seems to be unrealistic to state that the quality of postgraduate distance education at IGNOU at this level is of the highest standard. Nevertheless, the quality indicators or elements at IGNOU regarding student support services and the quality of course materials and assessment methods are clear evidence that indicate that IGNOU is addressing the issues of quality enhancement and improvement. There are, however, a number of factors which can affect the realisation of the potential of distance education programmes in Ethiopia. These are considered in terms of the operations of international providers of postgraduate studies and their role in meeting the increasing demand for quality human resource development in the country. In view of the findings and provided that the necessary conditions are met, it is possible to provide postgraduate studies in distance education programmes in Ethiopia in an efficient and successful manner. This requires careful planning and the alignment of the policy framework with the conventional system of higher education. The study further reveals a range of strengths and weaknesses in the postgraduate level distance education programmes offered by international providers and by IGNOU, in particular. The main areas of emphasis include the national education policy and its implications for distance education development and the entire institutional and pedagogic system of the cross-border institution; the focus of which includes course material development; the provision of various student support services; as well as the integration of ICT and assessment and evaluation methods. In the light of the above factors the study also identifies some strategies that can be used to develop and increase the effectiveness of these programmes. A significant strategy identified in this study recommends the need to decentralise services into different regional administrative centres. There is, therefore, a need to have comprehensively stocked libraries and quality student support services at the regional centres with adequate facilities for distance students including services, such as ICT, access to reference materials and counselling. Frameworks for assuring quality in open and distance learning, identified by Latchem and Jung in Asian Open and Distance Learning universities (ODL) (2007) and Lockhart and Lacy (2002) and an Assessment model used in the United States‘ distance education context were adopted for the purpose of analysis in this study. Latchem and Jung (2007) examine the various quality assurance approaches employed in Asian Open and Distance Learning universities (ODL). They make suggestions on how to achieve a culture of quality in distance education which is relevant in the context of developing countries, such as Ethiopia. The following three quality indicators were used as tools of analysis: coherence, efficiency and the impact of distance education. These indicators are identified by Perraton (2000:199) and are drawn from the quality criteria specific to distance education. They were adopted as a framework that could be applied to quality distance education in responding to human resource development in Ethiopia. The study reveals that access to postgraduate studies in the conventional face-to-face system in Ethiopia is still a problem for some students and workers. Therefore, it is recommended that international postgraduate distance education providers should collaborate with local private and public contact higher education institutions in order to provide alternative access to higher education via the distance education mode. / Thesis (PhD)--University of Pretoria, 2014. / tm2015 / Education Management and Policy Studies / PhD / Unrestricted

The purpose of this study was to gain an understanding of parents’ and teachers’ perceptions of parent-teacher communication, its purpose and how it is implemented in resource-constrained school settings. I employed a collective case study design involving four cases, namely parents of Grade 3 learners, parents of Grade 6 learners, Grade 3 teachers and Grade 6 teachers. I followed a qualitative research approach in order to gain rich, contextual information that portrays the perceptions of the participants. I identified three primary schools to participate by combining purposeful and convenience sampling strategies, and purposefully selected 11 teachers and eight parents as participants. Eight semi-structured interviews and two focus group discussions were conducted to collect data. In addition, I relied on observation, field notes and a research diary. Following inductive thematic data analysis, I identified the following themes: general modes of parent-teacher communication, purposes of parent-teacher communication, role-players and their expectations, factors negatively impacting parent-teacher communication, and strategies to move towards effective parent-teacher communication. Findings of the study indicate that the participating schools utilised written communication, telephone contact and meetings in person to exchange information with parents, in support of learners’ performance. Children, School Management Teams and the Department of Basic Education were identified as additional important role-players in communication. However, the attitudes, behaviours and preferences of teachers and parents as well as resource-constrained contexts can negativity influence parent-teacher communication. On the other hand, more effective use of technology, the creation of more opportunities for open dialogue and the commitment of all role-players can potentially enhance regular two-way communication between parents and teachers. / Dissertation (MEd)--University of Pretoria, 2017. / Educational Psychology / MEd / Unrestricted

The present paper is devoted to the investigation of the guided wave problem. This problem is formulated as the eigenvalue problem with a compact self-adjoint operator pencil. Applying the minimax principle for the compact operators in the Hilbert space we obtain a necessary and sufficient condition for the existence of a preassigned number of linearly independent guided modes. As a consequence of this result we also derive simple sufficient conditions, which can be easily applied in practice. We give a statement of the problem in a bounded domain and propose an efficient method for solving the problem.

The goal of the thesis is to examine possibilities of dynamic reconfiguration in real-time component systems, especially to formally describe support of operating modes. The thesis introduces a reconfiguration mechanism based on properties and relations between them. The mechanism is designed to facilitate a straight forward modeling of operating modes and reconfiguration rules and preserves re-usability of assembled components. The thesis also presents a realization of the mechanism suitable for the domain of embedded real-time systems.

Thesis advisor: Gabor J. Kalman / Mixtures of charged particles, where the components have different charge numbers (Z_A ), masses (m_A ) and densities (n_A ), with A = 1, 2 denoting the components, occur in Nature in a great variety. To be sure, even the simplest plasmas are necessarily multicomponent systems, consisting of negative and positive charges. This feature is, however, obscured within the centrally important and popular OCP (one component plasma) or jellium models, where the role of one of the components is reduced to providing a neutralizing background. When this background is inert, one is led to the Coulomb OCP model, while when the background is polarizable (such as an electron gas surrounding heavy particles), to a Yukawa OCP (YOCP), with a screened Yukawa potential replacing the Coulomb potential between the dynamically active particles. There are, however situations of physical importance, where the OCP description is inadequate and a genuine two component description of a plasma composed of two species is required. This Thesis focuses on the study of the dynamics of many-body systems consisting of two components of like charges (all the Z_A -s being of the same signature) in a neutralizing background. The methodology is based upon parallel attacks through theoretical analysis and Molecular Dynamics (MD) simulations, the latter yielding the capability of instant verification of the former. The investigation involves the study of the partial (i.e. species by species) structure functions S_AB (k, ω) and current-current correlation functions L_AB (k, ω). The Fluctuation–Dissipation Theorem (FDT) con- nects these quantities to the total and partial response functions χ_AB (k, ω) (matrices in species space), which are instrumental in the description of the collective mode excitations of the system. This analysis has revealed an entirely novel feature: both S_11 (k, ω) and S_22 (k, ω) exhibit very sharp and deep (several orders of magnitude) minima in the strongly coupled liquid phase at robust characteristic frequencies of the system, which are virtually coupling independent. The FDT then demands that these anti-resonances show up as well in the imaginary part of the partial density response function χ_AB (k, ω). Our theoretical analysis, based on the Quasi-Localized Charge Approximation (QLCA), has confirmed that this is indeed the case. These anti-resonant frequencies being related to the dissipative part of the response, require a physical description of the principal source of dissipation. This has been identified as the inter-species momentum transfer, governed by drag between the microscopic current fluctuations of the two species. The description of this effect was incorporatedv in the QLCA formalism, making it possible to derive a closed analytic representation of the fluctuation spectra in the frequency domain of interest and compare them with the results of the MD simulations. Other important novel concepts, such as the idea of coupling dependent effective mass, fast vs. slow sound, the mechanism of tran- sition from short-range to long-range interaction have been identified and analyzed. Furthermore, the investigation of the dynamics has led to the first comprehensive description of the mode structures of classical binary Coulomb and Yukawa mixtures at arbitrary coupling values, which has been a longstanding problem in statistical plasma physics. Focusing on the longitudinal excitations, we describe the transition from weak coupling (where one is acquainted with the RPA result yielding only the single plasmon mode in the Coulomb case or a single acoustic mode in the Yukawa case) to strong coupling, with a doublet of modes that arise from the complex rel- ative motion between the two components, as affected by the interaction with the background. / Thesis (PhD) — Boston College, 2019. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

Intrapreneur driven units in the municipal administration in Halmstad is a fairly new phenomenon that has not existed for more than seven years. In the study, employees and managers experience  about differences and similarities between the traditional mode of operation and intrapreneur were examined as well as their views on the application of the policy in practice. Quantitative and qualitative methods have been used to investigate managers and employees experience of both modes of operation. Empirical materials have been collected using previous research, interviews with the managers and a survey of the employees. Content of the municipality's policy for intraprenades has been linked to various theories and models, which form the basis for the study's questions. The study highlights the policy's personnel and operational perspectives.  The result shows several similarities between the operating modes. Positive differences are experienced in respondents participation, motivation and influence. What both professions feel is that these opportunities are not used by all employees. Positive effects with intrapreneurs from an economic perspective are reflected in, among other things, increased financial awareness of the staff. What is perceived negatively by both managers and employees is that they feel limited by the municipality's acquisition agreement. Some employees think that there may be too much of a financial hassle at their meetings. Policy is complied with on all of the units, except that it is the Home Care Board that originally wanted the formation of intrapreneur mode of operation and not the staff themselves.  The study shows no connection between employees experiences of motivation and their age, but motivation depends on whether they feel seen and confirmed by their manager. / Intraprenad i Hemvårdsförvaltningen i Halmstad är ett tämligen nytt fenomen som inte funnits längre än sju år. I studien har medarbetares och chefers erfarenheter och upplevelser kring skillnader och likheter mellan den traditionella driftsformen och intraprenad undersökts samt deras syn på policys tillämpning i praktiken. Kvantitativa och kvalitativa metoder har använts för att undersöka chefers och medarbetares erfarenheter av de båda driftsformerna. Empiriska material har samlats in med hjälp av tidigare forskning, intervjuer med cheferna och enkätundersökning av medarbetarna. Innehåll i kommunens policy för intraprenader har kopplats till olika teorier och modeller vilket utgör grunden för studiens frågeställningar. I studien belyses personal- och verksamhetsperspektiv i policy. Resultatet visar på flera likheter mellan driftsformerna. Positiva skillnader upplevs i respondenternas delaktighet, motivation och inflytande. Det som båda yrkesgrupperna upplever negativt är att dessa möjligheter inte utnyttjas av alla anställda. Positiva effekter med intraprenad ur ett ekonomiskt perspektiv visar sig bland annat i ökad ekonomisk medvetenhet hos personalen. Det som uppfattas negativt av både chefer och medarbetare är att de känner sig begränsade av kommunens uppköpsavtal. En del anställda tycker att det kan bli för mycket ”ekonomisnack”. Policy för intraprenader efterföljs på samtliga enheter förutom att det är Hemvårdsnämnden som ursprungligen önskat bildande av intraprenader och inte personalen själva.   Studien visar inget samband mellan medarbetarnas upplevelser av motivation och deras ålder. Motivationen beror snarare på om de känner sig sedda och bekräftade av sin chef.