During seismic events, inefficient steel moment frame building systems may exhibit soft-story failures. This thesis focuses on development and validation of a seismic retrofit strategy for avoiding soft-story failures in low-rise and mid-rise steel moment frame buildings. The considered retrofit strategy consists of a sufficiently stiff Rocking Core (RC) pinned to the foundation and pin connected to the existing frame. For demonstration purposes, two representative benchmark steel moment frames, which are modified from the three- and nine-story pre-Northridge steel moment frames designed for Los Angeles in the SAC Steel Project, are considered. Finite Element (FE) models of the benchmark buildings are developed with consideration of member yielding, connection rupture, and P-Delta effect, and validated using published results. Eigenvalue analyses are conducted to investigate the effect of the RC on system modal properties. It is found that in general the added RC with practical stiffness value does not significantly change the fundamental period and therefore does not attract excessive earthquake force to the system. In addition, nonlinear static pushover analyses are performed to address the beneficial contribution of the RC to the system under the performance objectives including immediate occupancy, life safety, and collapse prevention. The Monte-Carlo simulation technique is used to generate the random lateral force distribution required in the nonlinear static pushover analysis. It is found that RC works as expected in all considered scenarios and creates more uniform inter-story distribution along the vertical direction when it is sufficiently stiff. Furthermore, nonlinear dynamic analyses are conducted using three different ground motion suites (including two suites with ground motions having probabilities of exceedance of 2% and 10% in 50 years, and one suite with near-fault ground motions). It is shown that the systems with properly selected RC can achieve the Best Safety Objective defined in FEMA 356 and exhibit collapse prevention performance under near-fault earthquakes.

No description available.

No description available.

This project included the following goals: 1. To review and assess the geomorphology and lake morphometry of Mountain Lake, Giles County, Virginia with regard to its age and origin. This included production of an updated bathymetric map of Mountain Lake using Sonar imaging of the lake bottom. 2. To evaluate present trophic conditions in the lake waters. This analysis included the first-reported nutrient conditions for input streams to the lake and rainwater. 3. To collect representative "modern" bottom sediment samples and to analyze these sediment samples for sedimentological characteristics, diatoms , and terrestrial pollen. This analysis focussed on present environmental conditions in the lake, and the determination of modern diatom thanatocommunities. 4. To collect complete bottom sediment cores from the lake. Coring was done using a diver-assisted manual coring device designed specifically for this project. 5. To analyze Mountain Lake sediment cores for sedimentology, age determination, and temporal differences in sediment characteristics, diatoms and pollen. This analysis focussed on interpretation and documentation of environmental changes through the lake's history. Primary discharge from the lake presently occurs through a leaky subterranean pathway associated with the deepest, crevice-like portion of the lake. This discharge results in the crevice drain not filling shut with sediment despite its location within the lowest portion of the lake. The lake structure, crevice, and subterranean drain are associated with a regional lineation feature represented in part by the path of Salt Pond Drain and a small input stream ("I-4") to the lake. Initial damming was caused by downdrop of overlying rock. The damming is not complete, and the rate of discharge through time is controlled, in part, by regional tectonic events and by a balance of hydrologic conditions and sedimentation factors. The present lake is generally oligotrophic in nature, with phosphorus representing the major limiting nutrient. Rainfall presently represents the largest source of nutrient to the lake. Present diatom flora in Mountain Lake includes 66 individual taxa, representing 25 genera. Of these, 12 forms or species have not been reported in Virginia inland waters prior to this project. The diatoms reflect the oligotrophic and circumneutral nature of the lake. At least seven diatom thanatocommunities can be defined in the lake, based on taxa, delineated by depth and nutrient conditions. The ratio metric of planktonic to littoral diatoms can be used to estimate past water depths in the lake from bottom sediment. An orange clay layer at 5 cm from the modern sediment/water interface represents human intervention in lake history, namely the hotel and road building in the early 20th Century. The age of the lake is greater than 6000 years. Specific 14C from sediment produced dates of 1860 +100, 4220 +50 and 6160 +70 bp. Within this interval, at least 6 extended periods of low or empty lake level occurred (at approximately 100, 400, 900, 1200, 1800, and 4200 yrs bp). Several of these low intervals are likely to correspond with cool dry conditions co-incident with solar minima events. When the lake has been low or empty, it has tended to develop Sphagnum bog conditions with the low lake surrounded by open or wooded meadows. Terrestrial flora surrounding the lake appears to have remained relatively similar through 6100 years, although red spruce originally accompanied hemlock. / Ph. D.

Pallets are a critical component of logistics infrastructure. Approximately 1.9 billion pallets are used each year in the United States for transportation of goods, from raw materials to finished products. Solid wood pallets represent 90% to 95% of the pallet market. To run their operations, wood pallet companies deal with suppliers, customers, and other supply chain components. Each of the steps is important to deliver the right products, with the required quality, and in a timely fashion. However, there is little research about the industry's supply chain practices. The objective of this research is to increase the understanding of the U.S. wood pallet manufacturing industry, its supply chain management practices, and factors affecting the supply chain management processes. To accomplish the research objectives, a nationwide mail survey of wood pallet manufacturers was carried out. In total 1,500 companies were sent questionnaires and the response rate was 14%. A model for supply chain success factors was developed based on previous research and was analyzed using the results from the survey. Results of the survey provide an up-to-date profile of the US wood pallet industry. It was found that pallet production per company was 727,229 units on average during 2009. Out of the 1500 respondents, 38.6% indicated they were medium-sized companies (20 to 99 employees) and 53.9% small companies (1 to 19 employees). Thirty five percentage of respondents indicated that their sales were less than one million dollars and 43% from one to five million dollars. Also, 45% of respondents were involved in pallet recycling or repair, and these companies indicated that, on average, 42% of the material in a recycled pallet is, in fact, new material. Regarding Supply Chain practices, close to three-quarters (73.1%) of respondents sold their products directly to customers and the order lead time for raw materials to shipment was 1 to 10 days for 81.9% of companies. The most important factors for purchasing decisions are availability, cost, and reliability of supplier (all rated 4.4 in an importance scale from 1 to 5, respectively). Respondents' answers suggest a preference to work with domestic materials (rated 4.3); however, respondents also indicated that there is currently a high level of competition for raw materials (rated 4.3). Results also indicated that information technology (IT) appears to receive little attention from wood pallet manufacturers, given that the importance of items in this area were rated relatively low, especially the use of internet for purchasing and training in IT (rated 2.2 and 2.1, respectively). Lastly, 86.0% of respondents did not believe that their customers would be willing to pay a premium for environmentally certified pallets, citing cost as the major barrier for a higher demand of these products. Also, a theoretical framework of supply chain management was designed, developed, and tested with factor analysis, allowing identification of seven factors in the wood pallet supply chain: (1) environmental uncertainty, (2) information technology, (3) supply chain relationships, (4) value-added process, (5) supply chain management performance, (6) business management, and (7) customer satisfaction. Relationships between factors were tested using multiple linear regression. Results show that value-added process positively affects supply chain relationships, and these in turn are positively correlated to supply chain management performance and customer satisfaction. Results from this research are useful for the industry to formulate a well-informed supply chain management strategy by understanding the connections between the different supply chain management practices and the business performance and customer satisfaction. The information presented is also useful for organizations supporting the wood pallet industry to design more effective assistance and educational programs. / Master of Science

This thesis addresses the design of ferrite cores for inductive proximity sensors of the ECKO type. The purpose of this pursuit is to identify several ferrite cores that have the highest performance in terms of the sensor's sensing ability. The purpose of the ferrite core in these sensors is to concentrate and focus the alternating magnetic field produced by a current-carrying winding. The magnetic flux is specifically aimed at the sensor's metal target, and since the sensing operation is dependent on the generation of eddy currents within the metal target, the range at which the target can be detected is a direct function of how optimally the magnetic flux is cut by the target. In this study the target is a circular disk, just as is used in industry for standardization procedures. To begin with, a theoretical analysis is performed to identify those factors that affect sensing performance; this development makes use of fundamental electromagnetic theory. Subsequently, the performance of a score or so ferrite geometries is evaluated by computer simulation using the results of the theory to facilitate effective comparison. The computer simulation is performed using finiteelements based electromagnetics solver software from ANSOFT. Lastly, some of the geometries studied with the simulation are constructed and their sensing performance evaluated as verification of the simulation and its theoretical backing. / Master of Science

Neste trabalho estudamos um pouco de Teoria dos Grafos, abordando diversas definições e teoremas interessantes. Apresentamos o Teorema das Quatro Cores, desde o surgimento do problema com Francis Guthrie. Analisamos a demonstração do teorema realizada por Alfred Bray Kempe e sua refutação através do contraexemplo de Percy John Heawood. Analisamos também a demonstração do Teorema das Cinco Cores de Percy John Heawood. Porém, apresentamos a primeira demonstração válida do Teorema das Quatro Cores, como sua particularidade de ter sido feita com o auxílio de um computador. O trabalho é concluído com uma análise sobre os benefícios que o conhecimento de Teoria dos Grafos pode render aos alunos do Ensino Básico, e como professor o pode trabalhar este assunto em sala de aula, inclusive abordando o problema de coloração de mapas. / In this paper we study Graph Theory, addressing various definitions and interesting theorems. We present the Four Color Theorem, since the origin of the problem with Francis Guthrie. We analyze the proof of the theorem presented by Alfred Bray Kempe, and its refutation by Percy John Heawood counter-example. We also analyze the Percy John Heawood demonstration of the Five Color Theorem. Finally, we present the first valid proof of the Four Colors Theorem, with its peculiarity of having been done with the aid of a computer. We conclude with an analysis of the beneficial that the knowledge of Graph Theory can render students of Basic Education, and how a teacher can work this topic in the classroom, including addressing the problem of map coloring.

The propagation paths of sound in water can be somewhat complicated due to the fact that the sound speed in water varies with properties such as water temperature and pressure, which has the effect of curving the propagation paths. This thesis shows how sound propagation in water can be simulated using a ray-tracing based approach on a GPU using Nvidia’s OptiX ray-tracing engine. In particular, it investigates how much speed-up can be achieved compared to CPU based implementations and whether the RT cores introduced in Nvidia’s Turing architecture, which provide hardware accelerated ray-tracing, can be used to speed up the computations. The presented GPU implementation is shown to be up to 310 times faster then the CPU based Fortran implementation Bellhop. Although the speed-up is significant, it is hard to say how much speed-up is gained by utilizing the RT cores due to not having anything equivalent to compare the performance to.

Neste trabalho estudamos um pouco de Teoria dos Grafos, abordando diversas definições e teoremas interessantes. Apresentamos o Teorema das Quatro Cores, desde o surgimento do problema com Francis Guthrie. Analisamos a demonstração do teorema realizada por Alfred Bray Kempe e sua refutação através do contraexemplo de Percy John Heawood. Analisamos também a demonstração do Teorema das Cinco Cores de Percy John Heawood. Porém, apresentamos a primeira demonstração válida do Teorema das Quatro Cores, como sua particularidade de ter sido feita com o auxílio de um computador. O trabalho é concluído com uma análise sobre os benefícios que o conhecimento de Teoria dos Grafos pode render aos alunos do Ensino Básico, e como professor o pode trabalhar este assunto em sala de aula, inclusive abordando o problema de coloração de mapas. / In this paper we study Graph Theory, addressing various definitions and interesting theorems. We present the Four Color Theorem, since the origin of the problem with Francis Guthrie. We analyze the proof of the theorem presented by Alfred Bray Kempe, and its refutation by Percy John Heawood counter-example. We also analyze the Percy John Heawood demonstration of the Five Color Theorem. Finally, we present the first valid proof of the Four Colors Theorem, with its peculiarity of having been done with the aid of a computer. We conclude with an analysis of the beneficial that the knowledge of Graph Theory can render students of Basic Education, and how a teacher can work this topic in the classroom, including addressing the problem of map coloring.

Este trabalho investiga os pressupostos e fundamentos da Teoria das Cores de Goethe (Farbenlehre) como parte dos seus empenhos enquanto cientista da natureza. Apresenta a tradução de um texto seu sobre o método científico (Kautelen des Beobachters) e de um segundo texto sobre experimentos prismáticos (Beitrag zur Optik), no qual ele lança as bases do seu trabalho de mais de 30 anos sobre as cores. Estes textos, até então inexistentes em português, fornecem os subsídios para um entendimento mais amplo da Farbenlehre. E a pesquisa como um todo se orienta no sentido de contribuir para um resgate da fenomenologia goetheana para o ambiente cultural da atualidade. / This work investigates the principles and bases of Goethe\'s Theory of Colours (Farbenlehre\") as part of his studies as a Natures scientist. A translation of Goethe\'s essay on scientific methods (\"Kautelen des Beobachters\") and another on prismatic experiments (\"Beitrag zur Optik\"), where he sets the bases of his 30 years work on colours studies, are presented in this work too. The papers translated here were never before available in Portuguese, and they represent relevant subsidies for a comprehensive understanding of the \"Farbenlehre\". This research aims to contribute to the recovery of the Goethean\'s Phenomenology for the cultural enviroment of our days.