In this study, the response of a liquid-fueled resonant pulse combustor to changes in liquid fuel composition was investigated. Experiments were performed with gasoline- ethanol, gasoline-diesel, and gasoline-heptane mixtures selected to produce meaningful variations in the ignition delay time. A review of ignition quality tester (IQT) data provided an expected increase in the overall delay for gasoline-ethanol mixtures with increasing ethanol concentrations, and a decrease for gasoline-diesel mixtures with increasing diesel concentrations in the mixture. By taking the phase of the ion signal as an indicator of heat release timing, the experimental results showed an agreement of gasoline-ethanol cases with the IQT data with a near linear increase with increasing ethanol concentrations. However, for gasoline-diesel, there exit no linear relation with the IQT data. For the case of gasoline-heptane mixtures, the results showed a linear decrease in delay with increasing heptane concentrations. Furthermore, it was shown that small changes in the physical properties of the fuel can significantly in sequence the cold-start operation of the combustor and alter the coupling between the unsteady heat release and resonant acoustic pressure wave during resonant operation. Dynamic combustion chamber pressure, stagnation temperature and pressure are recorded after a fixed warm-up time to characterize the performance and operation of the device. Results are interpreted in the context of fuel sensitivity and performance optimization of a resonant pulse combustor for pressure gain turbine applications.

abstract: In this paper, the Software Defined Radio (SDR) platform is considered for building a pseudo-monostatic, 100MHz Pulse-Doppler radar. The SDR platform has many benefits for experimental communications systems as it offers relatively cheap, parametrically dynamic, off-the-shelf access to the Radiofrequency (RF) spectrum. For this application, the Universal Software Radio Peripheral (USRP) X310 hardware package is utilized with GNURadio for interfacing to the device and Matlab for signal post- processing. Pulse doppler radar processing is used to ascertain the range and velocity of a target considered in simulation and in real, over-the-air (OTA) experiments. The USRP platform offers a scalable and dynamic hardware package that can, with relatively low overhead, be incorporated into other experimental systems. This radar system will be considered for implementation into existing over-the-air Joint Radar- Communications (JRC) spectrum sharing experiments. The JRC system considers a co-designed architecture in which a communications user and a radar user share the same spectral allocation. Where the two systems would traditionally consider one another a source of interference, the receiver is able to decode communications information and discern target information via pulse-doppler radar simultaneously. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2019

The subject of this thesis is the study of liquid dielectric transmission lines and their potential application as an excitation source in high speed, high-repetition rate laser designs. The design problems associated with the construction of high repetition rate (khz), short wavelength lasers have been reviewed and the major shortcomings of conventional electrical driving circuits identified. The identification of these shortcomings and a review of the available literature on electrical circuits for various types of lasers suggested that liquid dielectrics and transmission lines could potentially have significant advantages over more conventional circuitry used in high repetition rate, short wavelength lasers. The construction of a set of three parallel electrode, liquid dielectric transmission lines was undertaken along with the associated electrical circuitry necessary for efficiently charging the system. The resulting electrical driving network was capable of delivering high voltage, 50 nsec square wave current pulses at repetition rates exceeding 1 khz. The major problems limiting the practical usefulness of the system include the design tolerances required of the electrode separation structure and the requirements for a circulation system to deionize and decontaminate the liquid dielectric in designs requiring high reliability of the electrical driving circuitry.

Diploma thesis is about application of ultrasonic pulse velocity method to determinate the strengths of cements, if there is a relevant calibration relation.

No description available.

Variable-rate technologies coupled with broadcast spray systems serve to reduce chemical inputs, misapplication of chemicals, and environmental pollution, thus improving profitability and sustainability. Sprayer variable rate control involves using pulse width modulation (PWM) solenoids and/or direct chemical injection to adjust the application rate. The objectives of this research were to: outfit a conventional broadcast sprayer with PWM and direct inject technologies; evaluate the accuracy of the PWM system to control application rate for strait line and turn segments; and characterize the direct injection system’s transport delay time. For the PWM evaluation, the mean flow rate and coefficient of variation of individual nozzles indicated consistent performance. For the direct injection evaluation, the manufacturer recommended plumbing scheme and injection point location resulted in unsatisfactory delay times, ranging from 105 to 150s for the 8 km h-1 (5 mph) speed and 60 to 90s for the 16 km h-1 (10 mph) speed.

No description available.

In this work, the properties of the liposomes, the artificially created vesicles by various methods, are explored by a resistive pulse method using micropipettes. The fact that vesicles are fundamental in the wide range of functionalities they fulfill as organelles strengthen the desire of understanding the properties of them. The motivation of this work comes from the significant roles that liposomes play in the development of targeted drug delivery systems. Among other significant variables, the size of liposomes is found to be one of the dominating parameters in liposome based drug delivery, and the correlation between liposome size and delivery efficiency is discussed. To help improving the size evaluation ability, a few mainstream methods for liposome size detection and measurements are reviewed. As a reliable and accessible alternative method for liposomes detection, the resistive pulse method is introduced and the measurement on liposomes size change upon pH gradient was performed using this method. With our current liposome composition, we found the size increases as environmental pH increases. Further investigation is performed with vesicular pH=6, 7, and 8, respectively. Lastly, the stability of the small unilamellar vesicles (SUV) was studied via resistive pulse method, by monitoring the size change of 50nm liposomes as function of time. A significant size change in freshly prepared 50nm liposomes is recorded. This information will provide invaluable knowledge for targeting tumor with tight tissues, where small size liposomes are needed.

<p> The pulse response of a full scale aeration tank is mathematically modelled with an arbitrary network of idealized perfectly mixed and plug flow component vessels. The model is fitted in the frequency domain, then inverse transformed to the time domain. The soluble carbon concentration curve of batch biokinetic run is modelled by a modified logistics equation and a piecewise linear expression. The mixing and kinetic models are combined to predict the degree of conversion assuming the degree of segregation, J, to be one. The pulse responses of a lab scale tank for varying water flow rates are also modelled by the same methods. An attempt is made to correlate the mathematical model parameters to the water flow rate. </p> / Thesis / Master of Engineering (MEngr)

Distributed optical fiber sensors offer unprecedented advantages, and the most remarkable one is the ability to continuously measure physical or chemical parameters along the entire optical fiber, which is attached to the device, structure and system. As the most recently investigated distributed optical fiber sensors, phase-sensitive optical time domain reflectometry (φ-OTDR), Brillouin optical time domain analysis (BOTDA) and Brillouin dynamic grating-optical time domain reflectometry (BDG-OTDR) techniques have been given tremendous attention on the advantage of quantitative measurements ability over high sensitivity and absolute measurement with long sensing distance, respectively. However, the accompanying limitations in terms of static measurement range, acquisition rate, laser frequency drifting noise, and spatial resolution limitations in these techniques hinder their performance in practical applications. This thesis pays particular attention to the above three distributed sensing techniques to explore the fundamental limitations of the theoretical model and improve the sensing performance. Before presenting the novel sensing scheme with improved sensing performance, an introduction about distributed fiber optical sensing, including three main light scattering mechanisms in optical fiber, the recent advancements in distributed sensing and key parameters of Rayleigh scattering- and Brillouin scattering-based sensing systems. After that, a study on the theoretical analysis of large chirping rate pulse generation and the theoretical model of using chirped pulse as interrogation signal in φ-OTDR, BOTDA and BDG-OTDR systems are given. In the disruptive experimental implementations, the sensing performance has been improved in different aspects. By using a random fiber grating array as the distributed sensor, a high-precision distributed time delay measurement in a CP φ-OTDR system is proposed thanks to the enhanced in-homogeneity and reflectivity. In addition, a simple and effective method that utilizes the reference random fiber grating to monitor the laser frequency drifting noise is demonstrated. Dynamic strain measurement with a standard deviation of 66 nε over the vibration amplitude of 30 με is achieved. To solve the limited static measurement range issue, a multi-frequency database demodulation (MFDD) method is proposed to release the large strain variation induced time domain trace distortion by tuning the laser initial frequency. The maximum measurable strain variation of about 12.5 με represents a factor of 3 improvements. By using the optimized chirped pulse φ-OTDR system, a practical application of monitoring the impact load response in an I-steel beam is demonstrated, in which the static and distributed strain variation is successfully reconstructed. To obtain an enhanced static measurement range without a complicated database acquisition process, a photonic approach for generating low-frequency drifting noise, arbitrary and large frequency chirping rate (FCR) optical pulses based on the Kerr effect in the nonlinear optical fiber is theoretically analyzed and experimentally demonstrated by using both fixed-frequency pump and chirped pump. Due to the Kerr effect-induced sinusoidal phase modulation in the nonlinear fiber, high order Kerr pulse with a large chirping rate is generated. Thus the static measurement range of higher order Kerr pulse is significantly improved. Chirped pulse BOTDA based on non-uniform fiber is also analyzed, showing a high acquisition rate that is only limited by the sensor length and averaging times due to the relative Brillouin frequency shift (BFS) changes are directly extracted through the local time delays between adjacent Brillouin traces from two single-shot measurement without frequency sweep process. BFS measurement resolution of 0.42 MHz with 4.5 m spatial resolution is demonstrated over a 5 km non-uniform fiber. A hybrid simultaneous temperature/strain sensing system is also demonstrated, showing a strain uncertainty of 4.3 με and temperature uncertainty of 0.32 °C in a 5 km non-uniform fiber. Besides, the chirped pulse is also utilized as a probe signal in the Brillouin dynamic grating (BDG) detection along the PM fiber for distributed birefringence variations sensing. The strict phase-matching condition only enables part of the frequency components within the chirped probe pulse to be reflected by BDG, giving an adjustable spatial resolution without photo lifetime limitation. The spatial resolution is determined by the frequency chirping rate of the probe pulse.