Deep Brain Simulation (DBS) has received attention in the scientific community for its potential to suppress epileptic seizures. To date, DBS has only achieved marginal positive results. We believe that a highly complex possibly chaotic (HPC) biologically inspired stimulation is superior to periodic stimulation. Using Radial Basis Functions (RBFs), we modeled interictal and postictal time series based on electroencephalograms (EEGs) of rat hippocampus slices while under low Mg2+. We then compared the RBF based interictal and postictal stimulations to the periodic stimulation using a Cognitive Rhythm Generator (CRG) model for spontaneous Seizure-Like Events (SLEs). What resulted was a significant improvement in seizure suppression with the HPC stimulators at lower gains as opposed to the periodic signal. This suggests that the use of biologically inspired HPC stimulators will achieve better results while confining the stimulation to a narrow region of the brain.

Neural circuit flexibility is fundamental to the production of adaptable behaviors. Invertebrate models offer relatively simple networks consisting of large, identifiable neurons that are useful for investigating the electrophysiological properties that contribute to circuit output. In particular, central pattern generating circuits within the crustacean stomatogastric nervous system have been well characterized with regard to their synaptic connectivities, cellular properties, and response to modulatory influences. Monoaminergic modulation is essential for the production of adaptable circuit output in most species. Monoamines, such as dopamine and serotonin, signal via metabotropic receptors, which activate intracellular signaling cascades. Many of the neuronal and network targets of monoaminergic modulation in the crustacean stomatogastric nervous system are known, but nothing is known of the signal transduction cascades that mediate the biophysical response. This work represents a thorough characterization of monoaminergic receptors in the crustacean stomatogastric nervous system. We took advantage of the close phylogenetic relationship between crustaceans and insects to clone monoaminergic receptors from the spiny lobster. Using a novel database mining strategy, we were able to identify several uncharacterized monoaminergic receptors in the Panulirus interruptus genome. We cloned one serotonin (5-HT2βPan) and three dopamine receptors (D1αPan, D1βPan, and D2αPan), and characterized them with regard to G protein coupling and signal transduction cascades. We used a heterologous expression system to show that G protein couplings and signaling properties of monoaminergic receptors are strongly conserved among vertebrate and invertebrate species. This work further shows that DAR-G protein couplings in the stomatogastric nervous system are unique for a given receptor subtype, and receptors can couple to multiple signaling pathways, similar to their mammalian homologs. Custom made antibodies were used to localize monoamine receptors in the stomatogastric ganglion, and in identified neurons. Pyloric neurons show unique receptor expression profiles, which supports the idea of receptor expression as an underlying mechanism for cell-type specific effects of a given modulator. Receptors are localized to the synaptic neuropil, but are not expressed in the membrane of large diameter processes or the soma. The localization of dopamine receptors in identified pyloric neurons suggests that they may respond to synaptic, paracrine or neurohormonal dopamine signals. This work also supports the idea that different types of signals can be generated by a single receptor.

Pulsed power generators are a key component in compact systems for generation of high-power microwaves (HPM). HPM generation by virtual cathode devices such as Vircators put high demands on the source. The rise time and the pulse length of the source voltage are two key issues in the generation of HPM radiation. This thesis describes the construction and tests of several inductive high power pulse generators. The pulse generators were designed with the intent to deliver a pulse with fast rise time and rectangular voltage. Therefore, the pulse generators are all based on discharges of transmission lines. The transmission lines used in the pulse generators are modern high voltage cables normally used in power transmission. All tested pulse generators have step up transformers as intermediate magnetic energy storage. Further, the pulse generators have contributed to the knowledge of compact designs. Closing switches is another important device in pulse generator architectures. In general, high power switching involving large currents and high voltages requires the use of robust switches. The switches used in the pulse generators of this thesis are of gas and liquid type.

Electric energy conversion is an important issue in today's society as our daily lives largely depend on the supplies of energy. Two energy sources are studied for conversion in the present thesis, ocean waves and hydropower. The work focuses on the generator and the transmission of its output to the electric grid. Different approaches have been used, over the years, to convert the energy in ocean waves, and the method presently used is based on a point absorber (buoy) directly coupled to a linear generator on the seabed. A varying alternating voltage is induced with such configuration, where both the amplitude and the frequency changes continuously. The target is to connect several units in a farm, and thereby decrease the fluctuations in power production. This is shown to be possible to accomplish with a rectifier connected to each generator. Transmission systems can be designed with converters and transformers to connect the farm to the electric grid onshore. Several aspects of the concept are considered as well as interconnection issues. Analytical calculations verified by finite element simulations and measured data are used to model the behaviour of a linear generator. A series expanded expression for the ideal no-load flux and EMF (electromotive force) is derived, which can be developed into an analytical transmission design tool. Hydropower has been used for more than a century. Today many of the stations from the mid 1900's are up for refurbishment. Studies with finite element calculations show that a higher electric efficiency can be obtained with a high voltage cable wound generator.

The use of high-voltage pulsed electric fields in biotechnology and medicine has lead to new methods of cancer treatment, gene therapy, drug delivery, and non-thermal inactivation of microorganisms. Regardless of the application, the objective is to open pores in the cell membrane and hence either facilitate the delivery of foreign materials inside the cell or to kill the cell completely. Pulsed power supplies are needed for electroporation, which is the process of applying pulsed electric fields to biological cells to induce a temporary permeability in the cell membrane. The applications of pulsed electric fields are dependent on the output pulse shape and pulse parameters, both of which can be affected by the circuit parameters of the pulsed power supply and the conductivity of the media being treated. <br /><br /> In this research, two Metal Oxide Field Effect Transistor (MOSFET)-based pulsed power supplies that are used for electroporation experiments were designed and built. The first used up to three MOSFETs in parallel to deliver high voltage pulses to highly conductive loads. To produce pulses with higher voltages, a second pulsed power supply using two MOSFETs connected in series was designed and built. The parallel and series MOSFET-based pulsed power supplies are capable of producing controllable square pulses with widths of a few hundred nanoseconds to dc and amplitudes up to 1500 V and 3000 V, respectively. The load in this study is a 1-mm electroporation cuvette filled with a buffer solution that is varied in conductivity from 0. 7 mS/m to 1000 mS/m. The results indicate that by controlling the circuit parameters such as the number of parallel MOSFETs, gate resistance, energy storage capacitance, and the parameters of the MOSFET driver gating pulses, the output pulse parameters can be made almost independent of the load conductivity. <br /><br /> Using the pulsed power supplies designed in this work, an investigation into electroporation-mediated delivery of a plasmid DNA molecule into the pathogenic bacterium <em>E. coli</em> O157:H7, was conducted. It was concluded that increasing the electric field strength and pulse amplitude resulted in an increase in the number of transformants. However, increasing the number of pulses had the effect of reducing the number of transformants. In all of the experiments the number of cells that were inactivated by the exposure to the pulsed electric field was measured.

This dissertation creates practical methods for Poincaré return mappings of individual and networked neuron models. Elliptic bursting models are found in numerous biological systems, including the external Globus Pallidus (GPe) section of the brain; the focus for studies of epileptic seizures and Parkinson's disease. However, the bifurcation structure for changes in dynamics remains incomplete. This dissertation develops computer-assisted Poincaré ́maps for mathematical and biologically relevant elliptic bursting neuron models and central pattern generators (CPGs). The first method, used for individual neurons, offers the advantage of an entire family of computationally smooth and complete mappings, which can explain all of the systems dynamical transitions. A complete bifurcation analysis was performed detailing the mechanisms for the transitions from tonic spiking to quiescence in elliptic bursters. A previously unknown, unstable torus bifurcation was found to give rise to small amplitude oscillations. The focus of the dissertation shifts from individual neuron models to small networks of neuron models, particularly 3-cell CPGs. A CPG is a small network which is able to produce specific phasic relationships between the cells. The output rhythms represent a number of biologically observable actions, i.e. walking or running gates. A 2-dimensional map is derived from the CPGs phase-lags. The cells are endogenously bursting neuron models mutually coupled with reciprocal inhibitory connections using the fast threshold synaptic paradigm. The mappings generate clear explanations for rhythmic outcomes, as well as basins of attraction for specific rhythms and possible mechanisms for switching between rhythms.

Communication security is a very important part of modern life. A crucial aspect of security is the ability to identify with near 100% certainty who is on the other side of a connection. This problem can be overcome through the use of random number generators, which create unique identities for each person in a network. The effectiveness of an identity is directly proportional to how random a generator is. The speed at which a random number can be delivered is a critical factor in the design of a random number generator. This thesis covers the design and fabrication of three ring oscillator based truly random number generators, the first two of which were fabricated in 0.13µ m CMOS technology. The randomness from this type of random number generator originates from phase noise in a ring oscillator. The second and third ring oscillators were designed to have a low slew rate at the inverter switching threshold. The outputs of these designs showed vast increases in timing jitter compared to the first design. The third design exhibited improved randomness with respect to the second design.

Skolfartyget M/S Calmare Nyckel, som ägs och opereras av Sjöfartshögskolan i Kalmar används i utbildningssyfte av både blivande nautiker och maskinbefäl.   Driften av NOHAB-dieseln, som används som generator, har varit problemfylld med ständiga och oförklarliga stopp. Det larmsystem som installerades av Oskarshamnsvarvet var högst bristfälligt. Larmsystemet var personfarligt då det var byggd på 230volt, dessutom var larmpunkterna byggda i serie med endast en stoppindikering. Avsaknaden av elritningar över systemet gjorde att bristerna i larmsystemet inte kunde felsökas. Dessutom fanns ingen indikering i kontrollrummet utan endast lokalt vid NOHAB-dieseln.   Vi har gjort en nyinstallation av larmsystemet på mer personsäkra 24VDC, med samtliga larmpunkter parallella och med tillhörande indikering på panel, både lokalt vid NOHAB-dieseln samt i pulpeten för god översyn av systemet. Vidare har vi gjort kompletta ritningar över systemet för en god överblick och möjlighet att felsöka. I rapporten beskriver vi tillvägagångssättet för problemlösningar som uppstått under arbetet med att skapa ett fungerande larmsystem. / School ship M/S Calmare Nyckel, owned and operated by the Maritime University of Kalmar is used for training by both prospective merchant marine officer as well as engineers. The operation of NOHAB-diesel, used as a generator, has been problematic with frequent and unexplained stop. The alarm system installed by the Oskarshamn Shipyard was highly dysfunctional. The alarm system was dangerous to personnel when it was built on 230volt, furthermore were the alarm points constructed in series with only a stop indication. The lack of electrical drawings of the system made it impossible to trouble shot the deficiencies in the alarm system. Moreover, there was no alarm indication in the control room but only locally at the NOHAB-diesel.   We have made a new installation of the alarm system with the higher personal safety 24VDC, with all the alarms parallel with the corresponding indication on the panel, both locally at the NOHAB-diesel and on the control table for good review of the system. Furthermore, we have made complete drawings of the system enabling a good overview and the ability to troubleshoot.In this report we describe the approach to the problem solutions that have emerged in the process of creating a functioning alarm system.

This thesis covers the modelling of a Heat Recovery Steam Generator (HRSG) in a Combined Cycle Power Plant(CCPP). This kind of power plant has become more and more utilized because of its high efficiency and low emissions. The HRSG plays a central role in the generation of steam using the exhaust heat from the gas turbine. The purpose of the thesis was to develop efficient dynamic models for the physical components in the HRSG using the modelling and simulation software Dymola. The models are then to be used for simulations of a complete CCPP.The main application is to use the complete model to introduce various disturbances and study their consequences inthe different components in the CCPP by analyzing the simulation results. The thesis is a part of an ongoingdevelopment process for the dynamic simulation capabilities offered by the Solution department at SIT AB. First, there is a theoretical explanation of the CCPP components and control system included in the scope of this thesis. Then the development method is described and the top-down approach that was used is explained. The structure and equations used are reported for each of the developed models and a functional description is given. Inorder to ensure that the HRSG model would function in a complete CCPP model, adaptations were made and tuning was performed on the existing surrounding component models in the CCPP. Static verifications of the models are performed by comparison to Siemens in-house software for static calculations. Dynamic verification was partially done, but work remains to guarantee the validity in a wide operating range. As a result of this thesis efficient models for the drum boiler and its control system have been developed. An operational model of a complete CCPP has been built. This was done integrating the developed models during the work with this thesis together with adaptations of already developed models. Steady state for the CCPP model is achieved during simulation and various disturbances can then be introduced and studied. Simulation time for a typical test case is longer than the time limit that has been set, mainly because of the gas turbine model. When using linear functions to approximate the gas turbine start-up curves instead, the simulation finishes within the set simulation time limit of 5 minutes for a typical test case.

During the last decade, the Internet usage has been growing at an enormous rate which has beenaccompanied by the developments of network applications (e.g., video conference, audio/videostreaming, E-learning, E-Commerce and real-time applications) and allows several types ofinformation including data, voice, picture and media streaming. While end-users are demandingvery high quality of service (QoS) from their service providers, network undergoes a complex trafficwhich leads the transmission bottlenecks. Considerable effort has been made to study thecharacteristics and the behavior of the Internet. Simulation modeling of computer networkcongestion is a profitable and effective technique which fulfills the requirements to evaluate theperformance and QoS of networks. To simulate a single congested link, simulation is run with asingle load generator while for a larger simulation with complex traffic, where the nodes are spreadacross different geographical locations generating distributed artificial loads is indispensable. Onesolution is to elaborate a load generation system based on master/slave architecture.