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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
481

Statistical analysis of deterministic textures in steel sheet production

Porrino, Alessandre January 2004 (has links)
Textured surfaces are universally adopted in the steel sheet production industry, and manufacturers are continuously improving the quality of the finished products through intense research in the surface characterisation field. Deterministic Surfaces are textured with specifically designed rolls in order to present a certain degree of regularity, which allows better control over the functional behaviour of the metal sheets. The regularity of the texture impressed on the steel sheets also allows unconventional approaches to surface characterisation and to the assessment of the texture's structure. Statistical analysis is the most effective way to target the isolation of the deterministic part of the surface, which represents the desired product, from the stochastic part, called ‘noise’ and associated with the inaccuracies of production and measurement. This work addresses the problem of characterisation of deterministic textures through statistical analysis, proposing innovative filtering techniques aimed at the realisation of an On-line Process Control System. Firstly the techniques proposed are theoretically formulated and studied, addressing in particular the physical meaning of the geometrical parameters extracted through statistical analysis of highly correlated portions of the textures. A method for isolating the deterministic textures present on a surface, called the Statistical Surface Filter, is presented and discussed in detail, and tested on existing laboratory samples. Secondly the filter is applied to preliminary measurements acquired by an innovative on-line measurement system currently under development, and evidence is shown that the technique is effective in separating the information regarding the regular patterns from the stochastic noise. The possible applications to on-line Statistical Process Control are discussed. Thirdly, the Statistical Surface Filter is tested on a set of measurements representing texturing rolls and textured sheets with different characteristics; statistical analysis of the surface parameters extracted from the filtered surfaces show that the technique allows the assessment of the different contributions of the various stages of the texturing process to the final product. Finally, a software package is implemented for the practical application of the filtering techniques and the parameters extraction; the algorithms that perform the statistical filtering are described and discussed, concluding with the operations of optimisation and fine-tuning for production-line implementation.
482

Young children’s understanding of line of sight

Boydell, Mark M. January 2005 (has links)
Previous research into children’s understanding of line of sight has led to differing conclusions as to when and how children become able to appreciate that their view of an object will be different from another persons’ view of the same object. This is probably due to the diversity of response methods required from the children as well as different types of tasks and settings being used between the experiments. The aim of the present thesis is to investigate systematically how children will fare across various settings and whether their comprehension of line of sight can be biased by the task’s setting. The first experiment assessed children’s understanding of line of sight through a tube that was bent to varying degrees of curvature and whether their response pattern would change when feedback was provided. Results showed that children have great difficulty performing correctly on this task, especially when the degree of curvature is small. The older children corrected their response pattern when feedback was provided but the younger children tended to persevere in their response pattern regardless of contradictory feedback. The second experiment looked at children’s performance when walls were used - half the walls were smooth gradual curves while the other half was walls made up of two segments that met to form an angle. Again the children were asked to predict if two dolls placed at opposite ends of each wall would be able to see each other. Results showed that though even young children have no trouble in performing correctly on the “angled” walls, performance on the curved walls was significantly poorer with the older children performing better than the younger children. The third experiment sought to quantify the point at which children deemed line of sight became possible. To do this we used a single “U” shaped trench with the children being asked if one doll could see another in various configurations. The results showed a strong bias towards over estimating visibility. The fourth experiment repeated the second experiment but used wooden trenches instead of walls but also sought to quantify the “switchover” point at which the children deem vision becomes possible between the two dolls. The difference between angles and curves was once again replicated as was the age difference. The fifth experiment compared children’s appreciation of line of sight through/along tubes, trenches and walls. This performance level varied strongly depending on the type of task the child was asked to perform upon with the tube proving to be the most difficult and the angled trench the easiest. The overall findings of the experiment pointed to a context-dependent performance, implying a piece-meal development of childrens’ comprehension of line of sight.
483

Probability of Bit Error on a Standard IRIG Telemetry Channel Using the Aeronautical Fading Channel Model

Nelson, N. Thomas 10 1900 (has links)
International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / This paper analyzes the probability of bit error for PCM-FM over a standard IRIG channel subject to multipath interference modeled by the aeronautical fading channel. The aeronautical channel model assumes a mobile transmitter and a stationary receiver and specifies the correlation of the fading component. This model describes fading which is typical of that encountered at military test ranges. An expression for the bit error rate on the fading channel with a delay line demodulator is derived and compared with the error rate for the Gaussian channel. The increase in bit error rate over that of the Gaussian channel is determined along with the power penalty caused by the fading. In addition, the effects of several channel parameters on the probability of bit error are determined.
484

Electron-Scattering Line Profiles in Seyfert Galaxy Nuclei

Weymann, R. J. 07 1900 (has links)
No description available.
485

MILLIMETER/SUBMILLIMETER SPECTROSCOPY OF TiO (X-3 Δr): THE RARE TITANIUM ISOTOPOLOGUES

Lincowski, A. P., Halfen, D. T., Ziurys, L. M. 01 December 2016 (has links)
Pure rotational spectra of the rare isotopologues of titanium oxide, (TiO)-Ti-46, (TiO)-Ti-47, (TiO)-Ti-49, and (TiO)-Ti-50, have been recorded using a combination of Fourier transform millimeter-wave (FTmmW) and millimeter/submillimeter direct absorption techniques in the frequency range 62-538 GHz. This study is the first complete spectroscopic characterization of these species in their X-3 Delta(r) ground electronic states. The isotopologues were created by the reaction of N2O or O-2 and titanium vapor, produced either by laser ablation or in a Broida-type oven, and observed in the natural Ti isotopic abundances. Between 10 and 11 rotational transitions J + 1 <-> J were measured for each species, typically in all 3 spin-orbit ladders Omega-1,2, and 3. For (TiO)-Ti-47 and (TiO)-Ti-49, hyperfine structure was resolved, originating from the titanium-47 and titanium-49 nuclear spins of I = 5/2 and 7/2, respectively. For the Omega = 1 and 3 components, the hyperfine structure was found to follow a classic Lande pattern, while that for Omega = 2 appeared to be perturbed, likely a result of mixing with the nearby isoconfigurational a(1)Delta state. The spectra were analyzed with a case (a) Hamiltonian, and rotational, spin-orbit, and spin-spin parameters were determined for each species, as well as magnetic hyperfine and electric quadrupole constants for the two molecules with nuclear spins. The most abundant species, (TiO)-Ti-48, has been detected in circumstellar envelopes. These measurements will enable other titanium isotopologues to be studied at millimeter wavelengths, providing Ti isotope ratios that can test models of nucleosynthesis.
486

Characterization of the tg(rgs4:mCherry) zebrafish line

Hallgren, Henrik January 2014 (has links)
Cell-to-cell communication is one of the fundamental requisites of making multicellular organisms. G protein-coupled receptors (GPCRs) are one of the most abundant receptor-types within vertebrates. They canonically mediate their signal via hetrotrimeric G proteins, and G protein signaling is regulated by regulators of G protein-signaling (RGS). One of these RGS proteins, RGS4, is preferentially expressed in the central nervous system of humans and has been strongly connected to dopaminergic signaling, along with a number of severe neuronal diseases. rgs4 is not well studied in the model organism Danio rerio, the zebrafish, with only two publications. In this project, a newly constructed transgenic line, tg(rgs4:mCherry), with the fluorophore mCherry regulated by the promoter element of rgs4 was characterized in order to investigate fidelity to endogenous rgs4 expression and the utility of the transgenic line. The mCherry expression is apparent by 48 hours post fertilization, and expression is found mainly in neuronal tissue. Cell bodies are visible only in some labeled areas, while other areas show a more diffuse signal indicative of projections. There is only one transgenically labeled area that also unambiguously expresses rgs4; the pronephric tubule. This line is therefore not particularly well suited for rgs4-specifc studies, but this does not discredit the fidelity of the construct. A transgenic line made with a site-directed technique would most likely confer the fidelity of the promoter to the expression of the fluorophore. A way of increasing the labeling resolution includes exchanging the mCherry fluorophore for one with stronger signal and a lower tendency to aggregate, e.g. eGFP. Increasing the resolution of the characterization, e.g. to the level of sub-nuclei or neuronal types, would serve to enhance the utility of the line. As it is, the tg(rgs4:mCherry) zebrafish line has limited uses, and yet it is not without them.
487

The Role of Retrotransposons in Gene Family Expansions in the Human and Mouse Genomes

Janoušek, Václav, Laukaitis, Christina M., Yanchukov, Alexey, Karn, Robert C. 09 1900 (has links)
Retrotransposons comprise a large portion of mammalian genomes. They contribute to structural changes and more importantly to gene regulation. The expansion and diversification of gene families have been implicated as sources of evolutionary novelties. Given the roles retrotransposons play in genomes, their contribution to the evolution of gene families warrants further exploration. In this study, we found a significant association between two major retrotransposon classes, LINEs and LTRs, and lineage-specific gene family expansions in both the human and mouse genomes. The distribution and diversity differ between LINEs and LTRs, suggesting that each has a distinct involvement in gene family expansion. LTRs are associated with open chromatin sites surrounding the gene families, supporting their involvement in gene regulation, whereas LINEs may play a structural role promoting gene duplication. Our findings also suggest that gene family expansions, especially in the mouse genome, undergo two phases. The first phase is characterized by elevated deposition of LTRs and their utilization in reshaping gene regulatory networks. The second phase is characterized by rapid gene family expansion due to continuous accumulation of LINEs and it appears that, in some instances at least, this could become a runaway process. We provide an example in which this has happened and we present a simulation supporting the possibility of the runaway process. Altogether we provide evidence of the contribution of retrotransposons to the expansion and evolution of gene families. Our findings emphasize the putative importance of these elements in diversification and adaptation in the human and mouse lineages.
488

Application of energy-based power system features for dynamic security assessment

Geeganage, Janath Chaminda 10 November 2016 (has links)
To date, the potential of on-line Dynamic Security Assessment (DSA) to monitor, alert, and enhance system security is constrained by the longer computational cycle time. Traditional techniques requiring extensive numerical computations make it challenging to complete the assessment within an acceptable time. Longer computational cycles produce obsolete security assessment results as the system operating point evolves continuously. This thesis presents a DSA algorithm, based on Transient Energy Function (TEF) method and machine learning, to enable frequent computational cycles in on-line DSA of power systems. The use of selected terms of the TEF as pre-processed input features for machine learning demonstrated the ability to successfully train a contingency-independent classifier that is capable of classifying stable and unstable operating points. The network is trained for current system topology and loading conditions. The classifier can be trained using a small dataset when the TEF terms are used as input features. The prediction accuracy of the proposed scheme was tested under the balanced and unbalanced faults with the presence of voltage sensitive and dynamic loads for different operating points. The test results demonstrate the potential of using the proposed technique for power system on-line DSA. Power system devices such as HVDC and FACTS can be included in the algorithm by incorporating the effective terms of a corresponding TEF. An on-line DSA system requires the integration of several functional components. The practicality of the proposed technique in terms of a) critical data communications aspects b) computational hardware requirements; and c) capabilities and limitations of the tools in use was tested using an implementation of an on-line DSA system. The test power system model was simulated using a real-time digital simulator. The other functional units were distributed over the Local Area Network (LAN). The implementation indicated that an acceptable computational cycle time can be achieved using the proposed method. In addition, the work carried out during this thesis has produced two tools that can be used for a) web-based automated data generation for power system studies; and b) testing of on-line DSA algorithms. / February 2017
489

Pressure Dependence of Line Widths of Microwave Spectra of Sulphur Dioxide

Yang, Wei Han 12 1900 (has links)
Measurements of line width parameters for eleven rotational transitions of type (J -- J + 1) of SO2 were made and are reported herein. The line width quantum number (J) trend was obtained. The microwave spectrograph used for these measurements of line width is described. Operational methods to operate the spectrograph are presented and discussed, with particular attention given to how to measure the line width. Suggestions for future avenues of probing this molecule to ascertain the non-uniform behavior of the line width parameter over the quantum number and frequency range are given.
490

Hand preference and manual midline crossing in 12-month-old infants

Logeswaran, Suthanthan January 2017 (has links)
Previous research has found that hand preference can be detected reliably in infants as young as 6 months of age through the use of reach-grasp tasks. While many studies have targeted their efforts at discerning hand preference in infants younger than 12-months of age, a lack of knowledge about hand preference during the ages of 1-2 years remain. The aim of the present study was to investigate whether 12-month-old infants demonstrate a clear hand use preference during unimanual reaching and grasping. Participants consisted of 54 healthy, full term 12-month-old infants (+2/-2 weeks). Goal objects were placed at a reachable distance, in front of the infants and randomly allocated to either left, midline or right positions. Infant hand choices and the success of each grasp were coded offline from video recordings made of the reach-grasp sessions and an overall lateralisation index (LI) was calculated later for each infant. The results demonstrated that the 12-month-old infants were generally right-preferred. Additionally, almost double the frequency of grasps were accounted for by right hand grasps. Further, a significant right hand preference was found when children reached across the midline to grasp objects. The findings imply that hand preference may be readily observed in the prehension activities of 12-month-old infants, and particularly prominent when reaching across the midline.

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