<p>  </p> <p>Electroporation uses puled electric fields to permeabilize cell membranes to either introduce exogeneous molecules into cells through normally impermeable membranes or completely lysing cells to induce cell death. This thesis examines electroporation in combination with a natural product for microorganism inactivation and pulsed magnetic fields for inducing pain remediation. Motivated by previous studies using curcumin with pulsed electric fields for cancer treatment, we hypothesized that this combined treatment modality could also enhance microorganism inactivation. The experiments did not indicate any synergistic benefit from combining curcumin and pulsed electric fields for microorganism inactivation. We also hypothesized that a pulsed magnetic field treatment could permeabilize neuron membranes to block action potentials to reduce pain without requiring drugs or direct intervention with the electric pulses. This thesis explored Sim4Life, a commercial software that coupled electromagnetic solvers with models of organisms to assess the interaction of pulsed magnetic fields with tissues. We designed and simulated a device for generating a pulsed magnetic field with different geometries to assess electric and magnetic field generation. These studies only considered pulsed magnetic fields and not specifically time-dependent currents or DC magnetic fields that could be benchmarked to standard analytic solutions. The process outlined here will enable future benchmarking for Multiphysics, multiscale simulations of pulsed magnetic fields, AC magnetic fields, or novel electromagnetic waveforms. The results for this thesis provide a starting point for future experiments coupling electroporation with natural products for microorganism inactivation and for assessing in vivo effects of external electromagnetic fields. </p>

In this episode, we show how a binary signal can be used to give the appearance of an analog output. We then use this understanding to show how to dim an LED on the Arduino open source platform.

Pages 10, 46, 126, 142 and 146 have been omitted because they were completely blank. / <p> This thesis describes the development of a tunable, ultrashort-pulse semiconductor-based laser system operating in the 1 μm wavelength region. The design of the oscillator is based on a two-contact long-wavelength InGaAs-GaAs quantum-well semiconductor device containing integrated gain and saturable absorber sections. A key design component of the oscillator is the fabrication of a curved ridge-waveguide in the gain section of the device, which allows the laser to be operated in a compact, linear external cavity. Under conditions of passive or hybrid mode-locking, the semiconductor oscillator can generate pulses of 1 to 10 ps in duration, which are tunable from 1030 to 1090 nm. The oscillator is also capable of being passively mode-locked at harmonics of the cavity round-trip frequency, allowing tuning of the pulse repetition rate from 0.5 to over 5 GHz. Noise measurements on two independently hybridly mode-locked semiconductor lasers reveal that the absolute noise of each laser is dominated by phase noise at frequencies below 10^5 Hz, while amplitude noise dominates at higher frequencies.</p> <p>Semiconductor and fibre optical amplifiers are used to scale the average power level of the mode-locked pulses. Semiconductor optical amplifiers consisting of narrow-stripe and flared-waveguide designs have been fabricated using the same material structure as that of the mode-locked semiconductor oscillator. Narrow-stripe devices with a length of 800 μm have produced amplified average signal powers of 13 mW, while 1700-μm-long, 2° flared-waveguide devices have produced amplified average signal powers of 50 mW. A fibre-based system consisting of a single-mode double-clad Yb-doped fibre has been constructed to investigate the suitability of a mode-locked diode laser as a seed-source for a Yb:fibre amplifier. Amplified average signal powers of up to 1.4 W have been obtained at the output of the fibre for a launched pump power of 2.1 W. Compression of the amplified pulses using a modified dual-grating compressor yields pulse durations as low as 500 fs and a peak power of up to 1.5 kW.</p> <p> Preliminary work is reported on the development of a novel dual-wavelength optical source consisting of two synchronized mode-locked diode lasers and a polarization-maintaining Yb:fibre amplifier. Numerical simulations based on a rate-equation model for the amplifier gain are conducted to investigate the performance characteristics of a Yb:fibre amplifier when operated under dual-wavelength signal amplification. The simulations are used to predict and optimize the performance of the fibre amplifier for two mode-locked semiconductor-seed-oscillators operating at wavelengths of 1040 and 1079 nm. Good agreement is obtained between the simulations and experimental results. </p> / Thesis / Doctor of Philosophy (PhD)

<p> This thesis deals with the problem of digital communication over noisy dispersive channels. The dispersion causes the overlapping of successive received pulses thus creating intersymbol interference which severely limits the performance of conventional receivers designed to combat only additive interference or noise.</p> <p> In this thesis Bayes estimation theory has been applied to obtain a new, optimum, unrealizable receiver structure for the improved reception of noisy, dispersed, pulse amplitude-modulated (PAM) signals. By making certain approximations, a realization of this structure, known as the estimate feedback receiver or equalizer, is obtained. It consists of the combination of a matched filter and a nonlinear, recursive equalizer having, in the case of binary signals, a hyperbolic tangent nonlinearity in the feedback path. The well known decision feedback equalizer is shown to be a small noise limiting case of the estimate feedback equalizer. A saturating limiter is also considered as an approximation to the hyperbolic tangent nonlinearity.</p> <p> A new adaptive algorithm for the iterative adjustment of the estimate feedback equalizer is derived. It incorporates an extrapolation process which has the purposes of accelerating convergence of the equalizer's parameters to their optimum values and of maintaining the equalizer's frame of reference. It is constrained so that the equalizers parameters always move toward their optimum values.</p> <p> Computer simulations are used to demonstrate the properties of the adaptive estimate feedback equalizer and to compare them to those of presently known equalizers. When the estimate feedback equalizer is used, without a matched filter preceding it, to equalize phase distorted channels, its performance is seen to be superior to that of existing equalizers. The performance of an equalizer using a saturating limiter in place of the optimum hyperbolic tangent nonlinearity is seen to be almost as good as that of the estimate feedback equalizer.</p> / Thesis / Doctor of Philosophy (PhD)

During the thesis work, a feasibility study of the BPPM error-correction protocol is performed. The beyond pulse position modulation (BPPM) protocol was invented at Ericsson AB and describes a modulation encoding using vertically and horizontally polarized single photons for optical transmission and error-correction. The thesis work is a mixture of both experimental laboratory work and theoretical software simulations which are intended to mimic actual optical fiber transmission. One aspect of the project work involves designing the optical communication system which is used to evaluate the probabilities of transmission errors in the form of false detections and losses of light. During the project work, the BPPM protocol is implemented and used for software simulated error generation and correction. With the available laboratory setup used as the point of reference, error-correction using the BPPM protocol is studied using pulses of light containing more than one photon. The results show that the BPPM protocol can be used to recover some of the information that is lost during optical fiber transmission. Factors such as the size of the codewords, the number of photons per pulse and detection efficiency of the utilized single photon detector (SPD) have a significant impact on the success of the transmission.

During the fabrication of solid electrical insulation, small cavities known as micro voids may form in the material. As electrical stress increases in this micro void, the breakdown probability also increases. This type of electrical breakdown is commonly known as partial discharge. Magnitudes of partial discharge currents are typically small but enough to cause degradation of the electrical insulation. To study degradation for fast-rise time voltage square pulse train, partial discharge measurement is needed. In current studies, partial discharge pulse widths have been measured in the range of nanoseconds. The best approach for measurement at ultra wide band frequencies is a bridge type measurement system, to reduce external noise and improve sensitivity to PD currents. The bridge configuration can be used with samples instead of one sample and one coupling capacitor. Identically created samples will have a close match for impedance and frequency response. This type of bridge also helps to reduce other sources of measured current such as the high displacement currents due to fast rise time square pulse voltage on the samples. Further improvement includes simultaneous measurements using a “linked” bridge configuration, where bridges share a common sample. A directly connected measurement current shunt should be used for high sensitivity with a uniform ultra wide band frequency response. Post-measurement digital signal processing (DSP) algorithms will perform the task of pulse discrimination and time delay from the pulse front. This research presents a method to improve the measurement of partial discharge when applied voltage is non-sinusoidal, with high frequency components. The improvements are apparent when square pulse voltage rise times are less than 50 ns. Ultra wide band measurements of physical samples will be performed for short time duration with a digital storage oscilloscope. A DSP algorithm is used to filter residual noise from the partial discharge current. The presented measurement technique for samples for this study is an original approach. Sample results demonstrate the effectiveness of the technique.

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