This thesis is concerned with the mathematical aspects related to the optimal cutting of an object whose three-dimensional shape has been accurately and robustly reconstructed using appropriately developed computer-vision tools. First, a brief introduction to various one- and two-dimensional packing problems is presented. The Constrained Rectangle Packing problem which allows for defects to be modeled is then formulated and an efficient algorithm for solving it is presented. The two-stage stock-cutting problem according to which a set of rectangular pieces of prespecified dimensions are to be cut from a general shape object with general shape holes or defective regions is then investigated. It is shown how mathematical morphological operators can be vised in order to determine the optimal shifting for a given cutting pattern and proved that the problem of obtaining the optimal cutting pattern is NP-hard. However, the optimal solution to the unconstrained problem using mathematical programming is proposed. For the general problem good sub-optimal solutions are obtained using the technique of simulated annealing. Stereo-vision techniques are then employed for the accurate shape determination of the object to be cut. A three-dimensional reconstruction technique based on projective geometry is formally analysed and guidelines for its robust application are given. Finally, emphasis is placed on the correspondence problem, which becomes very difficult in the case of non-coplanar features and cameras set at 90 degrees from each other. It is shown how to cast the problem into an optimisation framework and a branch and bound algorithm is used in order to obtain the optimal solution. For increased robustness a Hough-Transform-like algorithm is also suggested. Both synthetic and real experimental results are presented throughout the thesis in order to illustrate the validity and usefulness of the proposed algorithms.

No description available.

The removal of coherent noise generated by surface waves in land based seismic is a prerequisite to imaging the subsurface. These surface waves, termed as ground roll, overlay important reflector information in both the t-x and f-k domains. Standard techniques of ground roll removal commonly alter reflector information as a consequence of the ground roll removal. We propose the combined use of the curvelet domain as a sparsifying basis in which to perform signal separation techniques that can preserve reflector information while increasing ground roll removal. We examine two signal separation techniques, a block-coordinate relaxation method and a Bayesian separation method. The derivations and background for both methods are presented and the parameter sensitivity is examined. Both methods are shown to be effective in certain situations regarding synthetic data and erroneous surface wave predictions. The block-coordinate relaxation method is shown to have major weaknesses when dealing with seismic signal separation in the presence of noise and with the production of artifacts and reflector degradation. The Bayesian separation method is shown to improve overall separation for both seismic and real data. The Bayesian separation scheme is used on a real data set with a surface wave prediction containing reflector information. It is shown to improve the signal separation by recovering reflector information while improving the surface wave removal. The abstract contains a separate real data example where both the block-coordinate relaxation method and the Bayesian separation method are compared. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Interest in producing hybrid organic-inorganic (HOI) materials has increased rapidly due to the unique combination of properties from the organic and inorganic components. The goal of the research described is to develop various HOI materials and explore their applications in corrosion protection over aerospace aluminum alloys, impact resistant materials, and surface protection over thermoplastic substrates. As a replacement to toxic chromate inhibitors, enrivonmentally friendly magnesium-rich primers (Mg-rich primers) have been investigated to provide corrosion protection over aerospace aluminum alloys. HOI binders were produced from an alkoxy silane and silica via sol-gel chemistry, where the combined organic and inorganic components provide flexibility, adhesion, and barrier properties. The derived topcoated Mg-rich primers showed promising corrosion protection in a salt spray exposure test and are competitive with chromate-containing primers. The condensation catalyst, tetrabutyl ammonium fluoride (TBAF), played an important role in the performance of the HOI binders and the derived Mg-rich primers. It enabled higher crosslink density and better barrier properties, however, reacted with Mg particles during salt spray exposure and caused the formation of blisters. A non-ionic condensation catalyst, dibutyltin dilaurate (DBTDL), had lower catalyst strength, but was expected to eliminate the blister formation of topcoated Mg-rich primers. Perfectly alternating polycarbonate-polydimethylsiloxane (PC-PDMS) multiblock copolymers were produced to create transparent impact resistant materials by confining the size of the rubber domains. The PC-PDMS block copolymers maintained high transparency at up to 62 wt% PDMS and shorter block length gave rise to larger partial miscibility. By incorporating the PDMS blocks to dissipate energy, the PC-PDMS block copolymers had much better impact strength than pure PC oligomers. Thermoset polycarbonate-polyhedral oligomeric silsesquioxane (PC-POSS) coatings were investigated to serve as surface coatings on PC substrate to provide abrasion resistance. The covalent bonding allowed high POSS loading at up to 18 wt% without sacrificing the transparency. The solvent composition and curing conditions largely determined the surface and bulk properties of the coatings. The incorporation of POSS molecules significantly increased the char yield and mechanical strength of the thermoset coatings, making them promising in surface protection applications.

In this study, a block manufacturing process is investigated using simulation as a tool to optimize resource utilization. First, the problem statement and the objectives of the study are established. Second, various data are collected by means of time studies, interviews, and physical observation of the operation. Activity durations are stripped and their distributions are obtained by using computer technology. When all required data are collected, STROBOSCOPE is used to create a model of the entire production process. The model is verified and validated to ensure that it performs as intended before running experiments. Results from experiments are analyzed by the use of spreadsheets and graphs. Recommendations with respect to the current operation and future changes are proposed. In both instances, the unit cost and the production rate are used as the criteria to determine the most effective resource usage. In conclusion, the minimization of production costs increases profit for manufacturers, reduces the construction cost for contractors, and results in lower prices to the end users. Note: for more information about required softwares to run the simulation and the animation, please contact: Julio C. Martinez, Ph.D., Assistant Professor of Civil Engineering (Construction), Virginia Tech, Blacksburg, VA 24061-0105, voice: (540) 231-9420, fax: (540) 231-7532, e-mail: julio@vt.edu, http://strobos.ce.vt.edu / Master of Science

No description available.

The theme of the thesis is design of modern building in the largest inner courtyard in Brno. The task is to design a structure that will suitably complement the existing structure and also solve problems with traffic and pedestrian permeability, parking and so on. Additional layer is the work with incomplete historical context of urban design.

The subject of this thesis was to develop ideas about buildings in the former barracks set in Brno - Ponava. In the previous study, I designed urban system block development, which builds on the existing block structure of the environment and creates a lively mix of public, semi-public and private areas. The territory of the barracks is located between the streets and stall Štefánikova, among which is the difference in height of one floor - so I created a single-storey base, which I put into commercial space and underground parking. The base then grows a set of four houses - the street Štefánikova is oriented multi-functional building, which includes commerce, offices and apartments and offers residents a large common area balcony facing the courtyard. This house in volume creates a psychological barrier against noise and busy urban class and creating a peaceful environment inside the block. The three remaining houses are purely residential and the level of the courtyard are equipped with private atriums closable system. In the middle of the courtyard is a small park with mature trees and undeveloped corner serves as a children's playground.

The call for reform to raise student achievement has required educators, school leaders, and researchers to look for new methods to improve the learning process. One method used increasingly is block scheduling. Block scheduling is the restructuring of the school day into classes much longer than the traditional 50-55 minute class period. The purpose of this study was to determine high school principals’ and teachers’ perceptions of block scheduling in Mississippi high schools in three areas: achievement, attendance, and discipline. Many theorists believe that a person’s perceptions form the basis of reality for that person. If a teacher believes that block scheduling is effective, then for them, it is effective. Because some theorists believe that there is little to be gained from general studies that compare the objective results of block scheduling with the objective results of traditional scheduling since these comparisons have shown mixed results, this study addressed the social validity of block scheduling which is the extent to which participants perceive the worthiness of block scheduling. The research design used in this study was a cross sectional survey design. A researcher-developed survey instrument was used to collect data from teachers and principals in Mississippi high schools that had implemented block scheduling in the last 5 years. A total of 22 schools were used for the study. A 5 point Likert-type scale was used to measure respondents’ perceptions of the effectiveness of block scheduling on the three areas. While both principals and teachers appeared to have positive perceptions of the impact block scheduling has on student achievement, discipline, and attendance, principals had a more positive perception than teachers in all three areas. Both groups appeared to believe that student discipline was the most positively affected area, while attendance was the least positively affected. Recommendations based upon the findings of this study included conducting: (a) studies that include a larger sample of principals, (b) studies that identify student perceptions of block scheduling, and (c) studies to determine how important staff development is when implementing block scheduling.

In this work, we created shear thinning block copolymers that could be potentially utilized as an artificial vitreous replacement. The materials were created using poly(ethylene glycol) (PEG) and silicone polymers, respectively, due to their high biocompatibility. Both the ABA and BAB geometry triblock copolymers were created and were characterized using parallel plate and cone-and plate rheometers. It was observed that the materials from both geometries exhibited a decrease in viscosity with increasing shear rates, thus fulfilling the criteria of being a shear thinning material. The materials were also characterized under different aqueous conditions. It was observed that the materials with a higher PEG composition were better able to retain their physical structure – did not disperse into aqueous solutions – at higher water content levels. The materials that retained their structure were also shown to retain their shear thinning properties. In the absence of solvent, the opacity of the materials increased with increasing PEG composition ratio per copolymer chain. When exposed to different aqueous conditions, the opacity of the materials was found to decrease at specific water concentrations. Materials with larger PEG blocks required a greater water content to exhibit optimal light transmission. / Thesis / Master of Science (MSc)