http://hdl.handle.net/1957/7302 Search the Channel search http://ir.library.oregonstate.edu/dspace/simple-search http://hdl.handle.net/1957/9456 Title: Bang-bang control development of permeability changes in a membrane model <br/> <br/>Abstract: The application of systems and control theory to membrane physiology is presented here. Modeling efforts have focused on describing those physiologically realistic mechanisms which govern the regulation of membrane permeability in nerve. The motivation behind identifying such mechanisms lies in understanding the morphology of neural activity on a meaningful and analytically tractable level. The suggested merit of integrating control theory into the analysis lies in providing how a membrane effectively adapts to changes in permeability and through what governing mechanisms. The value in producing such an understanding lies in mirroring biological reality in a more formal manner than could be achieved solely through experimental means. A bang-bang control policy describing the permeability correction mechanisms is developed using Liapunov's Stability Criteria. Both changes in membrane potential and kinetic rates are required to implement the policy. The policy describes the inherent mechanisms of the membrane which act to drive its permeability from unstable firing to the resting potential state. It is shown that these permeability changes in state are governed by a switching function that depends on the membrane potential and a dominant controlling parameter. The control policy is discussed in the context of solutions of the Hodgkin-Huxley Equations of Ionic Hypothesis. <br/> <br/>Description: Graduation date: 1998; Presentation date: 1997-12-18 Wed, 17 Dec 1997 22:58:59 GMT http://hdl.handle.net/1957/9357 Title: A comparison of task scheduling algorithms on multicomputers <br/> <br/>Abstract: For many years, the von Neumann bottleneck has imposed speed limits on the execution of a program. Because of their sequential nature, von Neumann computers can only execute a single instruction at a time. Instructions that are side-effect free and can be executed in parallel must wait. In an effort to overcome this bottleneck, multicomputers have been developed and implemented. These multicomputers are a new class of computers based on multiple processors. With multiple processors available, instructions can be processed in parallel. However, now interprocessor communication (IPC) delays must be taken into account. A program that is run on several processors may take longer to execute than if it were run on a single processor. The focus of the speed limits has now changed. The new focus now hinges on the efficient partitioning of a program and allocation of those partitions to processors. Several algorithms have been developed to solve the problem of partitioning and scheduling. Three algorithms were studied under uniform conditions to determine the efficiencies of each. They were Internalization, Balanced Layered Allocation Scheme (BLAS) and Dynamic Level Scheduling (DLS). Simulation studies indicate that BLAS performs the best overall. These algorithms based their communications costs on a simplified IPC cost model. A more realistic message grouping IPC model was developed to test the accuracy of the algorithms which are based on the simplified model. These simulation studies indicated that the simplified model was a fairly accurate gauge of a more realistic system. <br/> <br/>Description: Graduation date: 1995; Presentation date: 1994-08-01 Sun, 31 Jul 1994 22:58:59 GMT http://hdl.handle.net/1957/9352 Title: A critical survey of the electric power supply in Greece <br/> <br/>Abstract: History, topography, and nature of people have influenced the development of electric power in Greece quite substantially. The power production per capita in Greece is very low as a result mainly of continual wars and an uneven distribution of population. In 1948, electricity was being supplied in the country only by small independent local companies which were using imported fuel. With the exception of the Capital Area, the service was quite poor and unable to supply the increasing demand for power. The installed capacity was 205,187 KW; however, although this capacity amounts to 32.44 watts per capita, the maximum demand was only 18.11 watts per capita because of inadequate transmission and distribution facilities as well as poorly maintained generating equipment. In 1948, the Greek Government decided to design and construct a new power system extending all over the country and using, as much as possible, available natural energy resources. According to this plan, a program was adopted of constructing seven generating stations having a total capacity of 520,000 KW. Five of these plants are hydroelectric projects while the other two are thermal, using locally-mined lignite for fuel. Furthermore, a transmission system, included in the program, will interconnect the above projects and cover the country as well as the areas where industrial development had been limited by a lack of electric power. The new system was designed under the supervision of Ebasco Services Incorporated of New York and is supposed to cover the power needs of the country as soon as it is completed. Today, two hydroelectric and one thermal projects are supplying the country with electric energy; the rest are under construction or in the design stage. The New Power Program adopted a frequency of 50 cycles as well as standard transmission and distribution voltages. The New Power Program has made a commendable start toward providing the country with a modern power system. A more extensive and more reliable transmission system should be developed as soon as possible. Transmission and distribution voltages should be standardized throughout the country. People should be encouraged to use electricity by reduction of taxes on electricity and appliances. A continuing study of power demand and available energy resources should be made and the system should be adjusted accordingly. <br/> <br/>Description: Graduation date: 1955; Presentation date: 1955-05-12 Wed, 11 May 1955 22:58:59 GMT http://hdl.handle.net/1957/8947 Title: Substrate noise coupling in ring oscillator-based phase locked loops <br/> <br/>Abstract: In this thesis, the performance degradation of a phase-locked loop due to substrate noise is examined. A new analytical equivalent circuit model for substrate noise coupling is derived for a heavily doped silicon substrate. The model has been validated with measured data from a 0.35 μm CMOS process. Since the model is physical, it can be used to predict substrate noise coupling without the need for extensive computer simulations using three-dimensional finite difference or Green's function solvers. This is followed by an evaluation of the effect of substrate noise in a PLL. A PLL test chip fabricated in a 0.13 μm CMOS process has been characterized over a wide range of substrate noise frequencies. The measured results combined with extensive simulations provide insight into the mechanisms for noise coupling in a PLL. Based on an understanding of the noise coupling, guidelines for minimizing the impact of substrate noise are presented. <br/> <br/>Description: Graduation date: 2009 Fri, 11 Jul 2008 23:11:20 GMT