Darbe tiriami iškraipymai audio sistemose ir kaip žmogaus klausa juos suvokia. Autorius sistemina tyrimus, bibliografinius įrašus. Pateikiama alternatyvi tyrimo metodika. Tyrimo rezultatai reikšmingi tobulinant garsinio signalo traktą. / This research is about distortion in audio systems and how human hearing perceives it. Author collects together data from other researches and compares them. The main goal of this research is to find, what type of audio distortion is most audible. Results of the work can be used to improve audio equipment design with properties of human hearing in mind.

Questa tesi si compone di tre parti e tratta di differenti aspetti inerenti l'organizzazione geopolica delle nazioni da un punto di vista teorico. Viene prestata particolare attenzione agli effetti della distribuzione del reddito. / This dissertation is composed of three papers and discusses different aspects of the geopolitical organization of countries from a theoretical point of view. Special attention is given to the effects of income distribution

The Blended-Wing-Body is a conceptual aircraft design with rear-mounted, over wing engines. Turboelectric distributed propulsion system with boundary layer ingestion has been considered for this aircraft. It uses electricity to transmit power from the core turbine to the fans, therefore dramatically increases bypass ratio to reduce fuel consumption and noise. This dissertation presents methods on designing the TeDP system, evaluating effects of boundary layer ingestion, modelling engine performances, and estimating weights of the electric components. The method is first applied to model a turboshaft-driven TeDP system, which produces thrust only by the propulsors array. Results show that by distributing an array of propulsors that ingest a relatively large mass flow directly produces an 8% fuel burn saving relative to the commercial N+2 aircraft (such as the SAX-40 airplane). Ingesting boundary layer achieves a 7-8% fuel saving with a well-designed intake duct and the improved inlet flow control technologies. However, the value is sensitive to the duct losses and fan inlet distortion. Poor inlet performance can offset or even overwhelm this potential advantage. The total weight of the electric system would be around 5,000-7,000 kg. The large mass penalties further diminish benefits of the superconducting distributed propulsion system. The method is then applied to model a turbofan-driven TeDP system, which produces thrust by both the propulsors array and the core-engines. Results show that splitting the thrust between propulsors and core-engines could have a beneficial effect in fuel savings, when installation effects are neglected. The optimised thrust splitting ratio is between 60-90%, the final value depends on the propulsor intake pressure losses and the TeDP system bypass ratio. Moreover, splitting the thrust can reduce the weight of the electric system with the penalty of the increased core-engine weight. In short, if the power density of the superconducting system were high enough, turboshaft-driven TeDP would be preferable to power the N3-X aircraft

Structural steel design standards recognize lateral torsional buckling as a failure mode governing the capacity of long span unsupported beams with wide flange cross-sections. Standard solutions start with the closed form solution of the Vlasov thin-walled beam theory for the case of a simply supported beam under uniform moments, and modify the solution to accommodate various moment distributions through moment gradient expressions. The Vlasov theory solution is based on the assumption that cross-sectional distortional effects have a negligible effect on the predicted elastic critical moment. The present study systematically examines the validity of the Vlasov assumption related to cross-section distortion through a parametric study. A series of elastic shell finite element eigen-value buckling analyses is conducted on simply supported beams subject to uniform moments, linear moments and mid span point loads as well as cantilevers subject to top flange loading acting at the tip. Cross-sectional dimensions are selected to represent structural steel cross-section geometries used in practice. Particular attention is paid to model end connection details commonly used in practice involving moment connections with two pairs of stiffeners, simply supported ends with a pair of transverse stiffeners, simply supported ends with cleat angle details, and built in fixation at cantilever roots. The critical moments obtained from the FEA are compared to those based on conventional critical moment equations in various Standards and published solutions. The effects of web slenderness, flange slenderness, web height to flange width ratio, and span to height ratios on the critical moment ratio are systematically quantified. For some combinations of section geometries and connection details, it is shown that present solutions derived from the Vlasov theory can overestimate the lateral torsional buckling resistance for beams.

Performance improvement of a 3-D configuration reconstruction algorithm using a passive secondary target has been focused in this study. In earlier studies, a theoretical development of the 3-D configuration reconstruction algorithm was achieved and it was implemented by a computer program on a system consisting of an optical bench and a digital imaging system. The passive secondary target used was a circle with two internal spots. In order to use this reconstruction algorithm in autonomous systems, an automatic target recognition algorithm has been developed in this study. Starting from a pre-captured and stored 8-bit gray-level image, the algorithm automatically detects the elliptical image of a circular target and determines its contour in the scene. It was shown that the algorithm can also be used for partially captured elliptical images. Another improvement achieved in this study is the determination of internal camera parameters of the vision system.

Line current distortion is an important issue to a high-power current source rectifier(CSR) system. There are two main challenges related to this issue. First, the CSR input LC resonance can be affected by the variation of the source inductance from the power system and the effects of the CSR DC side circuit, which may lead to a line current distortion higher than expected. Another challenge is that the traditional high-power CSR using Selective Harmonic Elimination (SHE) pulse-width modulation (PWM) technique attempts to eliminate certain harmonics in the PWM current, which limits its ability for line current harmonic control. To control the CSR line current harmonics, this thesis focuses on two aspects: 1) the analysis and design of CSR input filter to avoid unexpected input LC resonance, and 2) the development of a new PWM scheme that can compensate the effects of the grid voltage harmonics and DC link current ripples. The thesis work has been validated by simulations and on an experimental CSR prototype. / Power Engineering and Power Electronics

Facades are popular in modern buildings and are made of different materials such as pre-cast concrete, glass, aluminium, granite or marble and steel. During recent times seismic activity in densely populated areas has resulted in damage and a consequent loss of life. There were many types of building failure, including failure of building facade systems. Facade systems are highly vulnerable and fail more frequently than the buildings themselves with significant devastating effects. During an earthquake building frames suffer large interstorey drifts, causing racking of the building facade systems. The facade systems may not be able to cater for such large deformations and this can result in either functional or total failure at the facade connections or damage by pounding (impact) with adjacent facade panels. Façade failure and collapse can cause serious damage to buildings and injury to people in the vicinity. Moreover, facade represent between 10- 20 % or more of the total building cost depending on the size and importance of the facility and facade material (Facades1980). Considering the cost and safety issues, the importance of a well designed facade system on a building needs to be emphasised. In modern buildings, energy absorbing passive damping devices are very commonly used for energy absorption in order to manage the vibration response of multistorey buildings in an earthquake event. A number of manufactured dampers such as Viscoelastic and viscous, friction and yielding dampers are available. These dampers use a range of materials and designs in order to achieve diverse levels of damping and stiffness. This thesis is an investigation of the seismic behaviour of building facade systems and studies the effects of facade and connection properties on this response. The objectives with energy absorbing connections of the study are to determine and control facade distortions and to establish the required connection properties. Finite Element techniques have been used for modelling and analysis of the building frame, facade and connections. Time history analyses under earthquake loadings were carried out to determine the system response in terms of inter-storey drifts, facade distortions, differential displacement between facades and frames and the axial force in horizontal connections. Connection properties with respect to stiffness and energy absorption capability (or damping) have been modelled and varied to obtain the desired response. Findings illustrate the influence of these connection properties on system response and show that it is possible to control facade distortions to within acceptable limits. They also demonstrate that energy absorbing connections are able to reduce inter-storey drifts and mitigate the detrimental seismic effects on the entire building facade system.

It is well established that epigenetic modifications to the genome are crucial for the exquisite control of gene expression required for an organism to develop and differentiate. These modifications are maintained through mitotic rounds of cell division, but must be cleared and reset through meiosis in order for the cells of the early embryo to achieve totipotency. Although we know these mechanisms exist, the rules determining which modifications are established where on the genome and the genes involved in these processes remain poorly characterised. Much of what is known about epigenetic processes has come from studies in non-mammalian organisms, such as Drosophila. However, in our laboratory we have developed a mammalian system for identifying modifiers of epigenetic gene silencing. An ENU mutagenesis screen is being carried out using an inbred mouse line carrying a GFP transgene, with an erythroid-specific promoter, that is particularly sensitive to changes in epigenetic modifications. Currently, 14 mutant lines that display a heritable shift in GFP expression have been recovered. These have been termed Modifiers of Murine Metastable Epialleles (Mommes). When I began my PhD in 2005, we had not identified any of the mutations underlying the phenotypes observed. To confirm the efficacy of the screen, I have tested the effect of heterozygosity for null alleles of two known epigenetic modifiers, Dnmt3a and Dnmt3b, on expression of the GFP transgene. Heterozygosity for the Dnmt3b knockout allele does shift expression while heterozygosity for the Dnmt3a knockout allele does not. This highlights the limitations of the screen. With this particular screen we will only detect modifiers that are expressed during haematopoiesis in the bone marrow. I have also worked on MommeD5. MommeD5 is a semi-dominant, homozygous embryonic lethal mutation that acts as an enhancer of variegation. I have found that the MommeD5 allele carries a 7 bp deletion in the major histone deacetylase, Histone deacetylase 1 (Hdac1), and this significantly alters the C-terminus of the mutant protein. The finding of Hdac1 attests to the screen design. The MommeD5 homozygous mutants die at approximately the same time as the published knockout of Hdac1 and the heterozygous mutants show increased levels of Hdac2 and acetylated histone H3, as reported in Hdac1-deficient embryonic stem cells. In addition, I have studied the effect of heterozygosity for each of the mutations on the phenotype of the mouse. In general, heterozygous Momme mutants are viable and fertile, but show subtle abnormal phenotypes. However, in the case of MommeD5 none were observed and this may relate to the compensatory upregulation of other histone deacetylases. In the case of Dnmt3a and Dnmt3b a sex ratio distortion is seen in the colonies, with less males seen than expected. Also, Dnmt3a heterozygous mutant males that inherited the mutant allele from the dam are smaller and show an increased range of body weights compared to their wild-type male littermates. This may be an example of intangible variation, i.e. phenotypic variation observed in isogenic individuals raised in standardised environments. These results suggest that epigenetic mechanisms have a role in intangible variation, also known as developmental noise. Despite the fact that it is now acknowledged by many that stochastic events occur at the level of the cell, the idea that it can happen at the level of the whole organism is rarely considered.

There has been considerable recent interest in geometric function theory, nonlinear partial differential equations, harmonic mappings, and the connection of these to minimal energy phenomena. This work explores Nitsche's 1962 conjecture concerning the nonexistence of harmonic mappings between planar annuli, cast in terms of distortion functionals. The connection between the Nitsche problem and the famous Grötzsch problem is established by means of a weight function. Traditionally, these kinds of problems are investigated in the class of quasiconformal mappings, and the assumption is usually made a priori that solutions preserve various symmetries. Here the conjecture is solved in the much wider class of mappings of finite distortion, symmetry-preservation is proved, and ellipticity of the variational equations concerning these sorts of general problems is established. Furthermore, various alternative interpretations of the weight function introduced herein lead to an interesting analysis of a much wider variety of critical phenomena -- when the weight function is interpreted as a thickness, density or metric, the results lead to a possible model for tearing or breaking phenomena in material science. These physically relevant critical phenomena arise, surprisingly, out of purely theoretical considerations.

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on January 3, 2008) Includes bibliographical references.