Diese (Doktor)arbeit beschäftigt sich mit Radar-Polarimetrie, insbesondere mit der Untersuchung der Eigenschaften von polarimetrischen Variablen, die potenziellen Nutzen für die Radar-Meteorologie haben. Für den Einsatz in Dual-Polarisations-Radargeräten wird der Polarisationsgrad analysiert. Diese Variable wird in künftigen operationellen Radargeräten verfügbar sein. Der Polarisationsgrad hängt vom transmittierten Polarisationszustand und in weiterer Folge auch vom Betriebsmodus des Radargeräts ab. Der Hauptbetriebsmodus von operationellen Radargeräten sendet und empfängt gleichzeitig sowohl die horizontale als auch die vertikale Komponente. Der sekundäre Betriebsmodus sendet und empfängt simultan die horizontal polarisierte Komponente. In dieser Arbeit werden beide Polarisationsgrade untersucht. Da operationelle Systeme derzeit auf den Dual-Polarisationsmodus aufgerüstet werden, sollte künftig die Anwendungsmöglichkeiten von vollpolarimetrischen Wetterradarsystemen untersucht werden. Aus allen Variablen, die in diesem Betriebsmodus zur Verfügung stehen, wurde die Entropie (des gemessen Objektes) ausgewählt und wegen seiner engen Beziehung zum Polarisationsgrad näher untersucht. / The present doctoral thesis deals with radar polarimetry, namely with the investigation of properties of polarimetric variables potentially useful in radar meteorology. For use with dual-polarization radars, the degree of polarization is analyzed. This variable is available to planned operational radars. The degree of polarization is dependent on transmit polarization state and, consequently, it is dependent on the radar system operating mode. The primary operating mode of operational radars consists in simultaneous transmission and simultaneous receive of both horizontal and vertical components. The secondary operating mode consists of horizontal transmission and simultaneous receive. Both degrees of polarization are investigated in this thesis. Also, as operational systems are being updated to dual-polarization, research should start investigating the capabilities of fully polarimetric weather radar systems. Among the numerous variables available from this operating mode, the target entropy was chosen for investigation, also because of its close relation to the degree of polarization

In this study, excavation of jet-grouted tunnels in ground with strong time-dependent behavior is analyzed. The constant growth of population has led to a constant increase in the price of lands and thus infrastructures. Underground alternatives are becoming more economical. Furthermore, advances in the construction technology have made it feasible to construct tunnels in difficult ground conditions. By providing a grouted arch ahead of the tunnel face, jet-grouting has proved effective for the stability and performance of tunnels in difficult conditions. Given the limited depth of jet-grouting into the face, the jet-grouted arch is loaded soon after installation, when the rigidity of the grouted material is growing significantly. The simultaneous loading and hardening of the jet-grouting makes the tunnel response depend on the excavation rate. Furthermore, in difficult tunneling conditions, the ground material is associated with highly viscous behavior. This behavior is synonymous with delayed deformation depending on the level and duration of the ground loading by the tunnel excavation. In order to show the importance of the time-dependent behaviors, the full-face and the sequential excavation method are compared using three-dimensional and two-dimensional finite element analyses. First, a three-dimensional model is constructed and its results are validated against available analytical solutions for time-independent behaviors. The hardening of the jet-grouting is then introduced into the model by embedding jet-grouting elements through the analysis. In order to account for the ground viscous behavior, an advanced viscoplastic constitutive model is adopted, numerically implemented in FORTRAN, and used in conjunction with finite element software ABAQUS. The excavation methods are compared for the well documented study case of Tartaiguille tunnel. The results indicate that the full-face method outperforms the sequential method in the studied case by installing the tunnel invert closer to the face. The two-dimensional analysis of the tunnel is conducted by using the convergence-confinement method. To this end, a new approach is introduced to use the method for tunnels in time-dependent conditions. The effect of the jet-grouting hardening and the ground viscous behavior is characterized within the new approach by deriving the ground convergence curves. The reverse dependency of these mechanisms on the tunnel advance rate leads to an optimum advance rate, at which minimum tunnel convergence develops. / text

We introduce a mathematical framework for the inverse medium problem arising commonly in geotechnical site characterization and geophysical probing applications, when stress waves are used to probe the material composition of the interrogated medium. Specifically, we attempt to recover the spatial distribution of Lame's parameters ( and μ) of an elastic semi-infinite arbitrarily heterogeneous medium, using surface measurements of the medium's response to prescribed dynamic excitations. The focus is on characterizing near-surface deposits, and to this end, we develop a method that is implemented directly in the time-domain, is driven by the full waveform response collected at receivers on the surface, while the domain of interest is truncated using Perfectly-Matched-Layers (PMLs) to limit the originally semi-infinite extent of the physical domain. There are two key issues associated with the problem at hand: (a) the forward problem, namely the numerical simulation of the wave motion in the domain of interest; and (b) the framework and strategies for tackling the inverse problem. To address the forward problem, it is necessary that the domain of interest be truncated, and the resulting finite domain be forced to mimic the physics of the original problem: to this end, we introduce unsplit-field PMLs, and develop and implement two new formulations, one fully-mixed and one hybrid (mixed coupled with a non-mixed approach) that model wave motion within the, now PML-truncated, domain. To address the inverse problem, we adopt a partial-differential-equation-constrained optimization framework that results in the usual triplet of an initial-and-boundary-value forward problem, a final-and-boundary-value adjoint problem, and a time-independent boundary-value control problem. This triplet of boundary-value-problems is used to guide the optimizer to the target profile of the spatially distributed Lame parameters. Given the multiplicity of solutions, we assist the optimizer, by deploying regularization schemes, continuation schemes (regularization factor and source-frequency content), as well as a physics-driven simple procedure to bias the search directions. We report numerical examples attesting to the quality, stability, and efficiency of the forward wave modeling. We also report moderate success with numerical experiments targeting inversion of both smooth and sharp profiles in two dimensions. / text

The research followed up a local development initiative in Maracaibo, Venezuela, named Programa Promoción de la Ciudadanía Plena (Promotion of Full Citizenship Program), a joint initiative that has sought to bring the population of low-income communities to the sphere of citizen participation with a revaluation of citizenship and the promotion of participation. The research included first, a preliminary bibliographical review of the theoretical framework to understand the significance of citizenship and participation at the community level and the implications of organizational development and self-improvement approaches in development projects and institutions, and second, the review of the principles of the local program and the social-economic data of the four communities considered in the study. The results of a preliminary survey (secondary data provided by the municipality) of adult heads of household from the four communities, who openly expressed to the institutions their interest in participating and benefiting from the program, and the passive observation of local meetings and workshops in the communities contributed to the analysis. A series of open-ended interviews to facilitators (3 individuals) were conducted in 2006 in order to assess the facilitator's identification with the program's objectives and the possible bond between the learning assumptions and their personal experiences while working in these communities. That same year, a final series of open-ended interviews to a sample group of 39 beneficiaries (30% of the group that successfully completed the citizenship and technical education), provided the input to assess the impact of the program in the motivation of people toward participation and self-improvement. In these events, information was extracted, which contributed to the evaluation of people's expectations and attitudes, as they differed or not from the initial condition. A methodological guideline, in the form of field notes and questionnaires, was needed to address and manage conversation and dialogue. Following an interpretive and constructivist approach, evidence was inferred from the logic of the narratives gathered in meetings and interviews, and a coded frequency of responses. Findings suggest that the initiative strengthened local people's empowerment by involving them in the collaborative identification of problems and issues affecting their lives, in all activities planned to tie the relationship among stakeholders, and in every recognition and public ceremony. People's improvement depended on economic growth, but it was necessary that beneficiaries develop and exercise their capacities, abilities, knowledge, information and motivation, which were necessary conditions to improve the quality of life of local residents, and consequently, to strengthen the local social capital. Project agents did it with a respectful dialogue in the decision-making concerning the design and construction proposal, and recognizing people's own capacities, which assured collaboration and feedback. People did not participate unless they believed that an interest or individual benefit was possible; and for them, the immediate interest was economic. People associated changes to the following values --from high to low frequency of response: being more confident, reaching mutual support, improving communication, strengthening unity, consciousness, and achieving better social relations. Empowerment of the individual as head of household was strengthened by his or her involvement in the collaborative identification of household limitations and housing-related issues. Nevertheless, beyond the individual and household levels, the success of the educational strategy was not sufficiently effective to reach changes on people's attitude and motivation to confront and interact in the solution of community-related issues, but the increase of 6 percent in this indicator indicated that change was possible but required the sustainability of the educational approach in the communities. By the time the field research ended, a perceivable empowerment and partnership approach, with all the complex administrative and intellectual assumptions, guided Ciudadanía Plena toward its set goals. The attention and dedication in the four barrios were based on the need to materialize an ideal that was expected to expand in order to reach more communities in the near future. The transparency, the material incentive and the citizenship education to achieve self-improvement and empowerment were key elements to achieve change and improvement. / text

Tyrimo objektas: tiriamųjų funkcinės būklės ir gyvenimo visavertiškumo kaita, taikant kineziterapiją, atlikus širdies nuosrūvio suformavimą. Tyrimo problema: kineziterapijos pratimai ir reguliari fizinė veikla (namų tvarkymas, darbas lauke, lipimas laiptais, vaikščiojimas ar važinėjimas dviračiu) turi lemiamos reikšmės širdies ligomis sergančių pacientų fizinei būklei. Geresnė fizinė būklė lemia visavertiškesnį ir savarankiškesnį paciento gyvenimą (Bader et al., 2001). Tyrimo hipotezė: kineziterapijos taikymas du kartus į dieną (po širdies nuosrūvio suformavimo operacijos) bei ilgalaikė namų programa turėtų pagerinti pacientų funkcinę būklę ir gyvenimo visavertiškumą. Šio tyrimo tikslas: nustatyti funkcinės būklės ir gyvenimo visavertiškumo kaitą, taikant kineziterapiją po širdies nuosrūvio suformavimo. Tyrimo uždaviniai buvo: 1) nustatyti tiriamųjų funkcinę būklę ir gyvenimo visavertiškumą, praėjus 2-3 sav. po operacijos; 2) nustatyti tiriamųjų funkcinę būklę ir gyvenimo visavertiškumą, praėjus 4 sav. po sanatorinio gydymo; 3) nustatyti tiriamųjų funkcinę būklę ir gyvenimo visavertiškumą, praėjus 1 metams po kineziterapijos (namų programos). Tiriamieji. Tyrime dalyvavo 20 pacientų: vyrai, kuriems KMUK filialo Viršužiglio reabilitacinėje ligoninėje buvo taikoma kineziterapija. Pacientai buvo tiriami tris kartus: po operacijos, po sanatorinio gydymo ir po 1 metų namų programos. Tiriamiesiems, atvykus į Viršužiglio reabilitacinę ligoninę, po širdies nuosrūvio operacijos buvo... [toliau žr. visą tekstą] / Object of research: functional state and full value of life change when applying physio therapy after the surgery of heart blood flow adjustment. Problem. Physio therapy exercises and regular physical activities (housekeeping, working outside, going up the stairs, walking or riding a bicycle), have meaningful impact for the physio state of patients with heart disorders. Better physio state allows patient to have life of full value and helps to live independent (Bader et al., 2001). Hypothesis of research. Application of physio therapy after heart bypass twice a day and home programme should improve functional state and life value of the patients. The purpose of this research – evaluate functional state and life value of life change when applying physio therapy after heart blood flow adjustment surgery Research tasks were: 1) estimate patient’s functional state and full value of life 2-3 weeks after the surgery; 2) estimate patient’s functional state and full value of life 4 weeks after the treatment in sanatorium; 3) estimate patient’s functional state and full value of life 1 year after the home programme. Subjets: 20 patients took part in the research – men, who had physio therapy in KMUK subsidiary Viršužiglis rehabilitation hospital. Patients were tested three times: before surgery, after sanatorium and after one year home programme. Patients had physio therapy twice a day five days a week after the heart blood flow surgery in Viršužiglis rehabilitation hospital... [to full text]

Many potential small wind turbine locations are near obstacles such as buildings and shelterbelts, which can have a significant, detrimental effect on the local wind climate. This thesis describes the creation of a new model which can predict the wind speed, turbulence intensity, and wind power density at any point in an obstacle’s region of influence, relative to unsheltered conditions. Artificial neural networks were used to learn the relationship between an obstacle’s characteristics and its effects on the local wind. The neural network was trained using measurements collected in the wakes of scale models exposed to a simulated atmospheric boundary layer in a wind tunnel. A field experiment was conducted to validate the wind tunnel measurements. Model predictions are most accurate in the far wake region. The estimated mean uncertainties associated with model predictions of velocity deficit, power density deficit, and turbulence intensity excess are 5.0%, 15%, and 12.8%, respectively. / Industrial collaborators: Weather INnovations Inc., Wenvor Technologies Inc. / Ontario Centre of Excellence for Energy

Distributed generation that utilizes 5-10kW Solid Oxide Fuel Cells requires power electronics to optimize the overall system efficiency while reducing the cost. The Adaptive Energy Zero-Voltage-Switching Phase-Shift-Modulated Full-Bridge (AE-ZVS-PSM-FB) topology meets these criteria under all loading conditions, but suffers from complexity associated with an analog control implementation. This thesis presents a novel Look-Up-Table (LUT) based digital controller required for such converter. The applied design approach also reduces the design time and controller requirements, which in turn decreases the overall system cost. Steady-state analysis for the AE-ZVS-PSM-FB converter is performed using a piece-wise equivalent circuit model. This analysis is used to verify the LUT concept that forms the basis for the proposed LUT-based digital controller. The proposed LUT-based digital control algorithm is developed and verified using Field Programmable Gate Array (FPGA) Logic platform. Design procedures and operational function under steady state and step change conditions are presented. Simulation results demonstrate the LUT concept in the AE-ZVS-PSM-FB converter, and the simplicity of the proposed LUT-based digital controller in producing the expected switching sequence. Simulation results were also produced showing successful dynamic response of LUT-based digital controller interconnected with the converter under different operating conditions. A Xilinx FPGA demonstration board was used to generate experimental switching sequence results to demonstrate the simplicity of the proposed controller. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2007-09-25 10:26:39.909

Hydrothermally treated biomass could not only be used as a fuel or a fertilizer but it can also be refined into high-value products. Activated carbons are one of those. In the studies of this thesis, four different hydrothermally carbonized (HTC) biomasses, including horse manure, grass cuttings, beer waste and biosludge, have been successfully made into activated carbons. The activated carbon materials were in the forms of powdered activated carbons, powdered composites of activated carbon and iron oxide nano-crystals, and activated carbon discs. The HTC biomasses and the activated carbons were characterized and analyzed using several methods. The biomasses were carbonized to different extent during the hydrothermal treatment, which depended on the different natures of the biomasses. The HTC biomasses were activated into powdered activated carbons by both physical activation, using CO2, and by chemical activation, using H3PO4. Full factorial design matrices were applied to design experiments and study the influence of different parameters used during both physical and chemical activation. Activated carbons with embedded iron oxide nanoparticles were synthesized through hydrothermal carbonization followed by CO2 activation. These composites had high surface areas and showed a strong magnetism, and the powders could be separated from liquid phase by applying a magnetic field. Strong and dense activated carbon discs were also prepared from powdered HTC beer waste by pulsed current processing (PCP) and a subsequent CO2 activation procedure. The potential for carbon dioxide separation from nitrogen, and methylene blue adsorption in aqueous solution, were assessed for the powdered activated carbons produced from HTC biomasses. They showed good performance in both applications. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 1: In press.</p>

Full tensor gravity (FTG) data are known for their high resolution but also for higher noise in its components due to the dynamic nature of the platform used for data acquisition. Although a review of the literature suggests steady increase in the success of gravity gradiometry, we still cannot take advantage of the full potential of the method, mostly because of the noise with the same amplitude and wavenumber characteristics as the signal that affects these data. Smoothing from common low pass filters removes small wavelength features and makes it difficult to detect structural features and other density variations of interest to exploration. In Kalman filtering the components of the FTG are continuously updated to calculate the best estimation of the state. The most important advantage of the Kalman filter is that it can be applied on gravity gradiometry components simultaneously. In addition, one can incorporate constraints. We use the Laplace’s equation that is the most meaningful constraint for potential field data to extract signal from noise and improve the detection and continuity of density variations. We apply the Kalman filter on the FTG data acquired by Bell Geospace over the Vinton salt dome in southwest Louisiana.

The purpose of the study is to investigate optimal asset allocation as a means of minimising the investment risk, drawdown risk and longevity risk associated with an investment linked living annuity. The three risk elements were tested for various categories of retirees investing the full retirement savings amount in a living annuity. At first the paper examines the South African public's current pre-retirement savings habits, propensity to save and knowledge on the financial industry. The literature concludes that very few people are saving adequately for retirement, thus leaving a gap between required retirement savings capital and accumulated retirement savings capital. As a consequence, retirees have to take on more risk, usually in the form of equity exposure, (only available in an investment linked living annuity) or delaying retirement, to try and breach the gap. Secondly the paper examines the constructs in developing an optimal asset allocation. An analysis of the constructs includes risk versus return relationships for retirees, various unit trust sectors and portfolios within the South African financial market, the investment horizon also stated as the life expectancy of a retiree and withdrawal strategies applied by investors or retirees. The practical data and theory from the literature study formed the basis of the empirical study where different retirement savings balances were tested at various drawdown rates and asset allocations in an investment linked living annuity. The study concluded that retirees have to consider, among other factors, the required standard of living (stated as a net replacement ratio), the need to withdraw one third of the retirement capital and life expectancy before investing in an investment linked living annuity. These factors will have the biggest influence on the risks associated with an investment linked living annuity. Furthermore, the study concluded that an optimal asset allocation would be able to support a retiree during the post-retirement phase. A well diversified portfolio with a minimum of 50% allocation towards equity and property assets seems to be optimal. / Thesis (M.B.A.)--North-West University, Vaal Triangle Campus, 2010.