A new foil bearing with compression springs is designed, built, analyzed, and tested. This foil gas bearing uses a series of compression springs as a compliant structure instead of corrugated bump foils. A spring model to estimate the stiffness of compression springs was developed and showed a good level of agreement with the experimental results. The spring dynamics model was combined with a non-linear orbit simulation to investigate the non-linear behavior of foil gas bearings. The approach could also predict the structural loss factor given the geometry of the underlying springs. A series of rotor-bearing orbit simulations using the compression spring with stiffness of the free-free case, predicted the critical speed and the onset speed of instability at around 7500 rpm and 14,500 rpm with a WFR ~ 0.5. The low critical speed was due to the relatively soft support. The hydrodynamic rotor instability was predicted under the equivalent viscous damping extracted from the spring dynamics, implying the viscous damping alone within the spring cannot suppress hydrodynamic instability of the foil gas bearings. The load capacity of the compression spring foil gas bearing was measured at 20,000 rpm with and without air cooling, to demonstrate the feasibility of the new foil bearing. The constructed bearing with rather soft springs showed a small load capacity of 96N at 20,000 rpm under no cooling. The developed cooling method using direct air supply holes machined on the bearing sleeve, proved to be very effective in cooling the test bearing. The measured level of structural stiffness and damping evidenced the existence of a necessary level of damping for stable bearing operation. The structural stiffness was highly nonlinear and showed different behavior for static loading and the sinusoidal dynamic loading. The measured equivalent viscous damping coefficients increased with the applied load amplitude. A series of parametric design studies were performed to investigate the effects of various design parameters on the bearing stiffness and overall rotordynamic performance. Rotor-bearing orbit simulations showed there is a range of spring stiffness for high onset speeds of instability. Increasing the pitch of the spring while maintaining the same stiffness increased the structural loss factor slightly, manifesting a smaller number of coils is better in terms of damping. The onset speed of instability increases slightly with the rotor mass due to increased static eccentricity and presumably smaller cross-coupled stiffness. However, increasing the rotor mass in order to render a high eccentricity was not effective in increasing the onset speed of instability because of reduced natural frequency and increased inertia. Instead, orbit simulations confirmed that small rotor mass with external loading is the most effective way to increase the bearing stability.

Realistic predictions of service life of steel catenary risers (SCR) require an accurate characterization of seafloor stiffness in the region where the riser contacts the seafloor, the so-called touchdown zone. This thesis presents the initial stage of development of a simplified seafloor support model. This model simulates the seafloor-pipe interaction as a flexible pipe supported on a bed of springs. Constants for the soil springs were derived from finite element studies performed in a separate, parallel investigation. These supports are comprised of elasto-plastic springs with spring constants being a function of soil stiffness and strength, and the geometry of the trench within the touchdown zone. Deflections and bending stresses in the pipe are computed based on a finite element method and a finite difference formulation developed in this research project. The finite difference algorithm has capabilities for analyzing linear springs, non-linear springs, and springs having a tension cut-off. The latter feature simulates the effect of a pipe pulling out of contact with the soil. The model is used to perform parametric studies to assess the effects of soil stiffness, soil strength, trench geometry, amplitude of pipe displacements, pipe stiffness, and length of touchdown zone on pipe deflections and bending stresses. In conclusions, the seafloor stiffness (as characterized by the three spring parameters), the magnitude of pipe displacement, and the length of the touchdown zone all influence bending stresses in the pipe. Also, the tension cutoff effect, i.e., the pipe pulling away from the soil, can have a very large effect on bending stresses in the pipe. Neglecting this effect can lead to serious over-estimate of stress levels and excessive conservatism in design.

No description available.

Thesis (M.S.)--Montana State University--Bozeman, 2004. / Typescript. Chairperson, Graduate Committee: David M. Ward. Includes bibliographical references (leaves 60-65).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 114-134). Also available via the Internet.

Thesis (doctoral)--Philosophische Fakultät zu Upsala, 1899. / "Reprinted from Bull. of the Geol. Inst. of Upsala, no. 7, vol. IV, part. I, 1898." Includes bibliographical references.

Master of Science / Computing & Information Sciences / Daniel Andresen / When a software development company wants to achieve its goals on time and efficiently use its staff on the projects, it is necessary for the company to have hands on information related to number of employees working on various projects along with their skill set and the number of employees still needed to complete the projects on time. Resource Planner is a convenient tool to handle various projects in a software company efficiently. It is an online tool to manage projects currently running with the company as well as future projects. This tool tracks the employees working for the existing projects and details of new projects like no. of employees required, location, etc., and also estimates revenue which helps higher management to know the status of the various projects and work force. With this tool, HR can estimate the requirement of employees for the new projects and hence can recruit exact number of employees. The project manager can view the details of the employees in the company and the employees in his projects. He can also get the information of how many employees are there in a particular project and their skill set. When he wants employees for a particular project, he can add that information mentioning how many are working on the project and how many employees are totally needed for the project. This information can be had both for online and offline projects. This information is used in generating a special report called GAP summary. This application is developed using Java Spring MVC Framework and MySql database. The main goal of the project is to get familiar with Spring MVC Framework.

Master of Science / Department of Agronomy / Johanna A. Dille / Understanding the impact of early spring environmental conditions on kochia seed biology as well as time from flowering to seed maturation could suggest effective control practices. Kochia seed accessions were exposed to moisture stress or different phytohormone combinations across a range of temperature conditions to evaluate cumulative seed germination. Base temperature (T[subscript b]) and base water potential (ψb) were determined and used to calculate thermal (TT), hydro (HT), and hydrothermal (HTT) time to describe cumulative percent kochia germination across the environmental conditions. Base temperature was 2.7 C and ψb was -1.70, -1.62, and -0.92 MPa at 11, 6, and 4 C, respectively. To reach 50% cumulative seed germination, more days (2 and 11 d) and more TT (16.7 and 74.8 Cd) were needed as temperature decreased from 11 to 4 C and as water potential decreased from 0.0 to -1.2 MPa. Using the HT and HTT scale helped to account for effect of moisture stress. A small fraction of seeds under low temperature and high moisture stress germinated faster (10% at 6 C and -1.2 MPa) compared to more seed germinated at higher temperature and less moisture stress (91% at 11 C and -0.0 MPa). Addition of abscisic acid (10 µM ABA) decreased germination by 16% at both 23 and 6 C, while addition of gibberellic acid (10 µM GA) increased germination by 14% at both 23 and 6 C. Addition of ABA delayed time to 50% germination at 6 C compared to water, with 3 days or 10 Cd. Similarly, addition of GA shortened time to 50% germination at 6 C as it took 8.9 d and 29.3 Cd as compared to 10 d and 33 Cd in water. Kochia seed development was observed visually in greenhouse conditions after controlled and natural pollination. Kochia flower buds changed color from light green to dark brown by 36 days after pollination (DAP). At 36 DAP, buds had seeds enclosed in them but a germination study showed they were not yet viable. Hence, seed germination decreased and seeds needed more time to accumulate enough thermal and hydro unit before germinating as temperature and moisture stresses increased from 11 to 4 C and -0.0 to -1.2 MPa. We conclude that kochia seeds can germinate under very low temperature and moisture potential. Hence, should be controlled very early in the growing season. Phytohormones ABA and GA decrease and increase the germination of seeds, respectively. Kochia takes more than 36 DAP to produce viable seeds. Information on flower bud changes after pollination have implications for both kochia management and research.

The necessity to change the mechanism of the arm folding is to make a major difference in the field of Sun roofing systems and also to reduce the cost of the Awning system. The reduction of cost may help the market of the awning system to reach the Upper- Middle Class customers. In this project various technical solutions were investigated by simulation softwares and the data was taken into consideration. The best solution has been processed and investigated in depth with cost and material cost with high preference which cannot be exceeded when compared to today’s Awning arm folding solution. The best solution for replacing today’s mechanism is a torsion spring folding mechanism. The torsion spring has been designed and simulated using the SolidWorks simulation software. A virtual bench test of the Awning system has been created and designed using SolidWorks and the working mechanism has been tested virtually. The torsion spring’s data was calculated by using a spring dimension calculator. The spring data has been included in the bench test and the test simulation has been run by a virtual technique and then the result has been obtained by the virtual test bench. The torsion spring’s stress and strain analysis during maximum load on the Awning in an open condition has also been calculated for the study purpose of the spring stability and compared with the previous method of the awning system in order to calculate the factor of safety (FOS) equal or more stabilise for the environment as it has been used. The environmental condition is a main focus in this project. There are different types of weather conditions in Sweden. Customers may use the Awning during rainy weather. While it is raining the rain water are collected on top of the fabric. In order to withstand the weight of the water the arm of the awning should be strong. Hence the environmental condition is a main factor in this project with respective to speed of the wind. The economical manufacturing cost for the product and the replacement of the arm folding mechanism are mainly focused.

This study tested a model to predict the likelihood of spring break travel among university students. The data were obtained from a 1996 survey sample of 303 university students.