Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: In this work we investigate a new method to measure the electric field of ultrafast laser pulses by extending a known measurement technique, ptychography, in the spatial domain to the time domain which we call time domain ptychography. The technique requires the measurement of intensity spectra at different time delays of an unknown temporal object and a known probe pulse. We show for the first time by measurement and calculation that this technique can be applied with excellent results to recover both the amplitude and phase of a temporal object. This technique has several advantages, such as fast convergence, the resolution is limited by the usable measured spectral bandwidth and the recovered phase has no sign ambiguity. We then extend the technique to pulse characterization where the probe is derived form the temporal object by filtering meaning the probe pulse is also unknown, but the spectrum of the probe pulse must be the same as the spectrum of the temporal object before filtering. We modify the reconstruction algorithm, now called ptychographic iterative reconstruction algorithm for time domain pulses (PIRANA), in order to also reconstruct the probe and we show for the first time that temporal objects, a.k.a laser pulses, can be reconstructed with this new modality. / AFRIKAANSE OPSOMMING: In hierdie werk het ons ’n nuwe metode ondersoek om die elektriese veld van ’n ultravinnige laser puls te meet deur ’n bekende meettegniek wat gebruik word in die ruimtelike gebied, tigografie, aan te pas vir gebruik in die tyd gebied genaamd tyd gebied tigografie. Die tegniek vereis die meting van ’n reeks intensiteit spektra by verskillende tyd intervalle van ’n onbekende ‘tyd voorwerp’ en ’n bekende monster puls. Ons wys vir die eerste keer deur meting en numeriese berekening dat hierdie tegniek toegepas kan word met uitstekende resultate, om die amplitude en fase van ’n ‘tyd voorwerp’ te meet. Hierdie tegniek het verskeie voordele, die iteratiewe proses is vinnig, die resolusie van die tegniek word bepaal deur die spektrale bandwydte gemeet en die fase van die ‘tyd voorwerp’ word met die korrekte teken gerekonstrueer. Ons het hierdie tegniek uitgebrei na puls karakterisering waar die monster pulse afgelei word, deur ’n bekende filter te gebruik, van die onbekende ‘tyd voorwerp’ nl. die inset puls. Ons het die iteratiewe algoritme wat die ‘tyd voorwerp’ rekonstrueer aangepas om ook die monster puls te vind en ons wys dat ons hierdie metode suksesvol kan gebruik om laser pulse te karakteriseer

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Terahertz (THz) radiation is often used in many promising applications such as information and communication technology and airport security. Optimized and adapted terahertz fields hold huge promise for leading this technology further. This study is focused on terahertz time domain spectroscopy (THz-TDS). In THz-TDS the electric field is measured, therefore both amplitude and phase information of the THz pulse can be obtained. We used the pump-probe technique in order to measure a THz pulse from the photoconductive antenna. A pulsed fiber laser with FWHM of ' 100 fs was used for this. The frequency spectrum of the measured THz pulse was obtained via a fast Fourier transform. We studied the principles of the THz pulse generation as well as detection, with a photoconductive antenna as emitter and detector. In this study terahertz spectroscopy has been used to investigate the refractive index and absorption coefficient of different types of materials in the terahertz region. The last part of this study deals with a simple process for material parameter extraction of a polymer sample using commercial software called Teramat1.0. It uses the sample thickness, the reference THz pulse and the transmitted THz pulse to retrieve the complex refractive index of the sample. / AFRIKAANSE OPSOMMING: Terahertz (THz) straling word gereeld gebruik vir belowende toepassings soos inligting en kommunikasie tegnologie en lughawe sekuriteit. Geoptimeerde en aangepaste terahertz velde dra by tot die bevordering van die tegnologie. Hierdie studie fokus op terahertz tyd domein spektroskopie (THz-TDS). In THz-TDS word die elektriese veld gemeet en dus word beide amplitude en fase inligting van die THz puls verkry. Ons gebruik ’n pomp en toets tegniek om die THz puls deur ’n fotogeleidende antenna te bepaal. ’n Gepulseerde vesel laser met FWHM van 100 fs word hiervoor benut. Die frekwensie spektrum van die gemete THz puls word bereken deur ’n vinnige Fourier transvorm te bereken. Die beginsels van die generering en deteksie van THz pulse is bestudeer met ’n fotogeleidende antenna as sender en ontvanger. In die studie is terahertz spektroskopie gebruik om die brekingsindekse en die absorpsie koeffisiënte van verskillende materiale in die terahertz gebied te bepaal. Die laaste gedeelte van die studie handel oor ’n eenvoudige proses om die materiaal parameters van ’n polimeer te bepaal deur gebruik te maak van kommersiële sagteware Teramat 1.0. Die monster dikte, die THz verwysingspuls en die deurgelate puls word gebruik om die komplekse brekingsindeks van die materiaal te bereken.

by Ng Chi-Keung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 127-134). / Abstract also in Chinese. / Abstract --- p.2 / 摘要 --- p.3 / Acknowledgements --- p.4 / Chapter Chapter 1 --- Introduction --- p.7 / Chapter Chapter 2 --- Packaging Effects of Integrated Circuits --- p.9 / Chapter 2.1 --- The Structure of the IC Package --- p.9 / Chapter 2.2 --- Microstrip Discontinuities --- p.11 / Chapter Chapter 3 --- The Finite-Difference Time-Domain Method --- p.19 / Chapter 3.1 --- Basic Theory --- p.19 / Chapter 3.2 --- Stability Criterion --- p.25 / Chapter 3.3 --- Formulation of Source --- p.30 / Chapter A. --- Source Function --- p.30 / Chapter (i) --- Sinusoidal --- p.30 / Chapter (ii) --- Gaussian Pulse --- p.31 / Chapter B. --- Source Realization --- p.36 / Chapter (i) --- Electric Field Source --- p.36 / Chapter (ii) --- Lumped Source --- p.38 / Chapter (iii) --- Current Source --- p.40 / Chapter C. --- Source Placement --- p.41 / Chapter 3.4 --- Parameter Extraction --- p.42 / Chapter A. --- Voltage and Current --- p.42 / Chapter B. --- Characteristic Impedance --- p.44 / Chapter C. --- Effective Dielectric Constant --- p.45 / Chapter D. --- Scattering Parameters --- p.46 / Chapter 3.5 --- Termination and Boundary Treatment --- p.48 / Chapter A. --- Perfect Electric Conductor (PEC) --- p.48 / Chapter B. --- Perfect Magnetic Conductor (PMC) --- p.49 / Chapter C. --- Interface between Two Materials --- p.50 / Chapter 3.6 --- Perfectly Matched Layer (PML) --- p.54 / Chapter A. --- Theory of PML in Three Dimensions --- p.56 / Chapter B. --- Incorporation of PML as Absorbing Boundary Condition (ABC) --- p.65 / Chapter C. --- Discretization of Maxwell's Equations in PML --- p.73 / Chapter 3.7 --- Flowcharts --- p.75 / Chapter A. --- Free Space Radiation by a Dipole Antenna --- p.77 / Chapter B. --- Parameters of a Microstrip Line --- p.79 / Chapter C. --- Scattering Parameters of Planar Network --- p.85 / Chapter 3.8 --- Summary --- p.87 / Chapter Chapter 4 --- Effects of Ground Via Allocation --- p.88 / Chapter 4.1 --- Introduction --- p.88 / Chapter 4.2 --- Simulation and Experimental Results --- p.91 / Chapter 4.3 --- Equivalent Circuit Modelling --- p.108 / Chapter 4.4 --- Summary --- p.124 / Chapter Chapter 5 --- Conclusions --- p.125 / Chapter Chapter 6 --- Recommendation for Future Work --- p.126 / References --- p.127 / Publication --- p.134

This thesis presents a study of the sub-light year regions of Active Galactic Nuclei (AGN). These environments contain accretion discs that orbit a central super-massive black hole. The luminosity of the AGN inner regions varies over time across all wavelengths with variability at longer wavelengths lagging behind that at shorter wavelengths. Since the AGN themselves are too remote and too compact to resolve directly, I exploit these time lags to infer the physical characteristics of the accretion disc and surrounding gas clouds that emit broad emission lines. These characteristics include the inclination and temperature profile of the accretion disc, and the shape (or light curve) of the luminosity fluctuations that drive the accretion disc variability. This thesis details the work in the first author papers of Starkey et al. (2016, 2017), in which I detail the statistical code, CREAM (Continuum REverberting AGN Markov Chain Monte Carlo), that I developed to analyse AGN accretion disc variability. I apply the code to a set of AGN light curve observations of the Seyfert 1 galaxy NGC 5548 by the AGN STORM collaboration (De Rosa et al., 2015; Edelson et al., 2015; Fausnaugh et al., 2016a; Goad et al., 2016; Starkey et al., 2017). I also present work detailing my variability analysis of the Seyfert galaxies NGC 6814, NGC 2617, MCG 08-11-11 and NGC 4151. This work has contributed to the analysis presented in (Troyer et al. 2016, Fausnaugh et al. submitted). I also investigate the implications of a twin accretion disc structure (Nealon et al., 2015) on the disc time lag measurements across near UV and optical wavelengths. I finish by detailing a modification to CREAM that allows it to merge continuum light curves observed in a common filter, but taken by multiple telescopes with different calibration and instrumental effects to consider.

by Yuen-Pat Lau. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 127-[129]). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- VLSI Interconnects in Circuits --- p.1 / Chapter 1.2 --- Propagating Waves on Interconnects --- p.4 / Chapter 2 --- Theory: FDTD --- p.6 / Chapter 2.1 --- Modelling Microstrips in FDTD Mesh Space --- p.6 / Chapter 2.2 --- FDTD Implementation of a Unit Cell --- p.8 / Chapter 2.3 --- FDTD Implementation of a Lumped Element --- p.12 / Chapter 2.4 --- FDTD Implementation of a Circuit --- p.14 / Chapter 3 --- Theory: TDMS --- p.20 / Chapter 3.1 --- FDTD Circuit Simulation --- p.20 / Chapter 3.2 --- TDMS: Microstrip Characterization --- p.22 / Chapter 3.3 --- TDMS: Parameter Extraction --- p.23 / Chapter 3.4 --- TDMS: Circuit Simulation --- p.26 / Chapter 4 --- TDMS Simulations --- p.30 / Chapter 4.1 --- Example One: Loaded Diode --- p.30 / Chapter 4.2 --- Example Two: Unbalanced Mixer --- p.38 / Chapter 5 --- TDR Experiments --- p.54 / Chapter 5.1 --- Example Three: Uniform Microstrip --- p.54 / Chapter 5.2 --- Example Four: Coupled Microstrip --- p.61 / Chapter 5.3 --- Example Five: Change-in-width Microstrip --- p.67 / Chapter 6 --- Conclusion --- p.78 / Chapter 7 --- Program Listing --- p.80 / Chapter 7.1 --- Example Two: Unbalanced Mixer --- p.80 / Chapter 7.2 --- Example Five: Change-in-width Microstrip --- p.110 / Bibliography --- p.127

No description available.

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Smith, Glenn; Committee Member: Buck, John; Committee Member: Goldsztein, Guillermo; Committee Member: Peterson, Andrew; Committee Member: Scott, Waymond. Part of the SMARTech Electronic Thesis and Dissertation Collection.

No description available.

Microfluidic techniques have allowed for fast, sensitive, and low cost applications of the Polymerase Chain Reaction (PCR) through the use of small reaction volumes, rapid amplification speeds, and the on-chip integration of upstream and downstream sample handling processes including purification and electrophoretic separation functionality. While such systems are capable of measuring the expression levels of thousands of genes simultaneously, or in hundreds of cells, or with sample-in and answer-out capability, none of these systems are easily scalable in the time domain. Because of this, the field of gene expression measurement has yet to fully utilize the advantages of microfluidic PCR in developing systems to measure changes in gene expression in increments of hours rather than days. In this project, we developed a microfluidic RT-qPCR system that utilizes infrared heating and open-loop control to reliably reverse transcribe, amplify, and detect samples in a single 1 μl polymer chip. Optimized power profiles were created that allow for fast heating and cooling rates while minimizing undershoot and overshoot from the desired hold temperatures. By utilizing repeatable microfluidic chip manufacturing techniques, and by controlling the environment around the chip, the same open loop program can repeatedly amplify multiple samples without any need for temperature feedback or recalibration between runs. Furthermore, the system was designed to operate on top of a fluorescence microscope to enable real-time fluorescence detection and quantification of starting copy number. By eliminating complicated setup procedures and calibration runs, this system increases the practicality of measuring gene expression at a high temporal frequency.

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: W.-P. Huang Includes bibliographical references (leaves 124-136).