Mechatronics Systems Engineering - Theses, Dissertations, and other Required Graduate Degree Essays

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3D Failure Analysis of Fuel Cell Electrodes using Multi-Length Scale X-ray Computed Tomography

Author: 
Date created: 
2016-09-06
Abstract: 

X-ray computed tomography (XCT), a non-destructive technique, is proposed for three-dimensional, multi-length scale characterization of complex failure modes in fuel cell electrodes. Similar to medical CT scanners, laboratory XCT enables low-intensity X-ray imaging of a specimen at different incident angles followed by reconstruction into three-dimensional views. Fuel cell materials are compatible with this technique as they are sufficiently transparent to X-rays. In this thesis, electrode failures are analyzed by comparative tomography data sets for conditioned beginning of test (BOT) and degraded end of test (EOT) membrane electrode assemblies subjected to cathode degradation. Cracks and thickness of the cathode catalyst layer (CCL) are analyzed at the micro length scale, followed by a complementary nano length scale analysis of the fine porous structure. Additionally, a novel image processing based technique is developed for nano scale segregation of pore, ionomer, and Pt/C dominated voxels in the degraded CCL. The results of this work reveal several failure modes of catalyst layers including but not limited to carbon corrosion, Pt agglomeration, and Pt migration. In summary, XCT based multi-length scale analysis enables detailed information needed for comprehensive understanding of the complex failure modes observed in fuel cell electrodes.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Erik Kjeang
Woo Soo Kim
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Waste heat-driven adsorption cooling systems for vehicle air conditioning applications

Date created: 
2015-10-01
Abstract: 

Waste heat-driven adsorption cooling systems (ACS) are potential replacements for vapor compression refrigeration cycles in vehicle air conditioning (A/C) applications. Working pairs in an ACS are a combination of an adsorbent material (e.g., zeolite and silica gel), and an adsorbate (e.g., water and methanol). Most of these materials are non-toxic, non-corrosive, non-ozone depleting, and inexpensive. Besides, an ACS operates quietly and valves are its only moving parts. However, the bulkiness and heavy weight of ACS are major challenges facing commercialization of these environmentally friendly systems.The focus of this research is to develop a proof-of-concept ACS with high specific cooling power for vehicle A/C applications. As such, this Ph.D. dissertation is divided into three main parts: (i) adsorbent material characterization, (ii) adsorber bed design, and (iii) ACS design. In-depth analytical and thermodynamic cycle models are developed to understand the phenomena in adsorption process, adsorber bed and ACS. Also, a modular two-adsorber bed ACS equipped with thermocouples, pressure transducers and flow meters is designed and built for the first time at the Laboratory for Alternative Energy Conversion (LAEC) to test different adsorbent materials, adsorber beds, condensers, and evaporators under different operating conditions. A low-operating pressure evaporator with capillary-assisted tubes is designed and installed on the testbed to improve the performance of ACS. In addition, a novel expansion valve and control valves are proposed to simplify the control system and reduce the complexity of ACS for vehicle A/C applications. Using this ACS testbed with enhanced performance, a specific cooling power of 150 W/kg of dry adsorbent is achieved.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Dissertation) Ph.D.

Development of an Adaptive Fuzzy Logic System for Energy Management in Residential Buildings

Date created: 
2015-08-26
Abstract: 

Heating, Ventilation, and Air Conditioning (HVAC) systems are the main target for energy and load management in residential buildings due to their high energy consumption. The role of Thermostats is to automatically control the HVAC systems while users accommodate their everyday schedules and preferences. The initiatives such as demand response (DR) programs, Time of Use (TOU) rates, and real-time pricing (RTP) are often applied by smart grids to encourage customers in order to reduce consumption during peak demand periods. However, it is often a hassle for residential users to manually reprogram their thermostats in response to smart grid initiatives and/or environmental conditions that vary over time. In this thesis, the research endeavors are dedicated to bring forward a novel autonomous and adaptable system for control of residential HVAC systems which results in an “Adaptive Smart Thermostat”. To do so, a “House Simulator” is developed in MATLAB-GUI with thoughtful consideration as a tool to facilitate the study of energy management for residential HVAC systems in smart grids. The simulator also assists in the implementation and verification of our proposed techniques under different scenarios such as RTP, various user schedules, and different environmental conditions. Furthermore, a new algorithm using rule-based fuzzy logic and wireless sensors capabilities for residential demand-side management is developed. The algorithm is augmented into existing programmable communicating thermostats (PCT) in order to enhance the learning capability of PCTs during participation in DR programs. The conducted results show that the PCT equipped with our approach, versus existing PCTs, performs better with respect to energy and cost saving, while maintaining user thermal comfort. The achieved results led us to develop a novel “Autonomous Smart Thermostat” that is the result of a synergy of supervised fuzzy logic learning, wireless sensor capabilities, and smart grid incentives. The results demonstrate that the developed thermostat autonomously adjusts the set point temperatures in ASHRAE thermal comfort-zone, while not ignoring the energy conservation aspects. However, in cases that the user overrides the decision(s) made by autonomous system, a novel “Adaptive Fuzzy Learning Model” utilizing wireless sensor capabilities is developed in order to learn and adapt to user new preference and schedule changes based on rulebased fuzzy logic learning. The results show that the developed system is adaptable, smart, and capable of intelligent zoning control while it improves energy management in residential buildings without jeopardizing thermal comfort.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Siamak Arzanpour
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Mechanical Modeling and Characterization of Cancer Cells Using Optical Tweezers

Author: 
Date created: 
2016-06-15
Abstract: 

In this thesis, the development of a novel optical tweezer is described. Additionally, alterations in the mechanical properties of cancer cells associated with metastatic transformation was characterized using this technology. Cell mechanical properties can be utilized as a quantitative measure for understanding the pathophysiological behavior of cells and evaluating pharmacological treatments that modify the cell structure. Thus, an oscillating optical tweezer capable of applying time varying force and manipulating the cell cytoskeleton was developed in order to measure the mechanical properties and structural changes of single epithelial cancer cells and blood cancer cells. Employing this device would be beneficial in differentiating between normal, cancer and metastatic cancer cells and evaluating the effectiveness of different chemotherapeutic approaches. To this end, the developed tool was utilized to conduct a systematic study of the mechanical properties of human epithelial cancer cells by mimicking the condition that causes cancer cell invasiveness and tumour cell transformation. Different signaling pathways that modulate actin organization under hypoxia were studied via analyzing the biophysical properties of cancer cells and quantifying cytoskeleton rearrangement employing the oscillating optical tweezer. It was demonstrated the optical tweezer is a novel, rapid and reliable tool for the identification and characterization of cancer cells and for evaluating therapeutic performance. Finally, a sensitivity study was applied using COMSOL to evaluate the effect of cell-bead geometries on cell mechanical responses for different cell types and optical tweezer experiments.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Edward Park
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

MEMS Hermetic Packaging for Extremely Sensitive Accelerometers with In-Package Pressure Sensing Solution

Author: 
Date created: 
2016-06-10
Abstract: 

In Micro-Electro-Mechanical Systems packages, sealing pressure is one of the most important indicators of packaging quality. Traditional hermeticity testing methods are expensive and inconvenient. Solution for in-package pressure monitoring has long been appealing. Pirani sensor is a commonly used pressure sensor that can be integrated into Micro-Electro-Mechanical Systems packages. Our team is developing a hermetic packaging process for extremely sensitive and low noise accelerometers. A eutectic package sealing process is developed and evaluated. To verify the stability of environment inside the package, a lowcost, process flow compatible, space saving bondwire Pirani sensor has been explored. The sensing principle is based on resistance change of the filament is a function of pressure under constant electrical power. The feasibility of using the bondwire Pirani sensor has been thoroughly discussed. A novel four point measurement set up is implemented to achieve the accurate low resistance measurement. The bondwire Pirani sensor has a dynamic range from 0.1 Torr to about 50 Torr and is compatible with any micro-system such as resonators, gyroscopes, micro-mirrors, and micro-display systems among others. The sensor is applied to our own packaging process as pressure sensing element to detect pressure change. Long-term pressure stability for sealed packages is also measured by the bondwire Pirani sensor.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Behraad Bahreyni
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

RCPC: A Multi-agent System for Coordinated Control of Power Electronic Converters in Microgrids

Author: 
Date created: 
2016-05-25
Abstract: 

The objective of this thesis is to describe the implementation of an innovative agent-based architecture of controllers for stand-alone DC microgrids. The controllers have to regulate voltage to the required level and manage energy flow in the system. In addition, they should maintain a deterministic time frame on the order of a few tens of milliseconds for a system with tens of power electronic converters with no limitation in the number of events which might happen concurrently. Optimal power sharing ensures minimum transmission and distribution loss while enforcing constraints such as generators’ capacity limits. Multiple agents take part in the process to determine optimum power sharing for the converters. The thesis compares system complexity using numerical analysis of different distributed lookup algorithms based on defined metric values for a standalone DC microgrid including 32 converters. The numerical analysis results aid in choosing a publish-subscribe model as the most efficient and scalable solution for developing agent technology for standalone DC microgrids. Application of publish-subscribe agent-based control is presented for real-time coordination of power converters in a defined microgrid. To test the design, a sample DC shipboard microgrid with eight converters is used as a case study. Results of implementing the agent-based publish-subscribe control system using Java Agent DEvelopment Framework (JADE) are illustrated in the thesis. Simulation results affirm the accuracy of numerical analysis results.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Mehrdad Moallem
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Empirical Membrane Lifetime Model for Heavy Duty Fuel Cell Systems

Author: 
Date created: 
2015-07-17
Abstract: 

Heavy duty fuel cells used in transportation system applications such as transit buses expose the fuel cell membranes to conditions that can lead to lifetime-limiting membrane failure via combined chemical and mechanical degradation. Highly durable membranes and reliable predictive models are therefore needed in order to achieve the heavy duty fuel cell lifetime target of 18,000 h. In the present work, an empirical membrane lifetime model was developed based on laboratory data from a suite of accelerated membrane durability tests. The model considers the effects of cell voltage, temperature, oxygen concentration, humidity cycling, humidity level, and platinum in the membrane using inverse power law and exponential relationships within the framework of a general log-linear Weibull life-stress statistical distribution. The obtained model is capable of extrapolating the membrane lifetime from accelerated test conditions to use level conditions during field operation. Based on typical conditions for the Whistler, British Columbia fuel cell transit bus fleet, the model predicts a stack lifetime of 17,500 h and a membrane leak initiation time of 9,200 h. Validation performed with the aid of a field operated stack confirmed the initial goal of the model to predict membrane lifetime within 20% of the actual operating time.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Erik Kjeang
Department: 
Applied Sciences:
Thesis type: 
(Thesis) Ph.D.

An Energy-Regenerative Vehicle Suspension System – Development, Optimization, and Improvement

Author: 
Date created: 
2016-08-23
Abstract: 

With the rapid development of hybrid and fully electric vehicles, electromagnetic suspensions have shown great potential for capturing energy while offering high-level ride comfort. The objective of this research was to develop an electromagnetic-based vehicle suspension system that allows for regeneration of road-induced vibration energy and supplies better dynamics control. A small-scale proof-of-concept system consisting of a mass-spring-damper system, ball screw mechanism, and direct current (DC) machine was designed. The vibration energy in the mass-spring-damper system caused vertical motion of sprung mass and the ball screw mechanism to convert the translational motion into rotary motion, which resulted in the generation of back electromotive force of the DC machine. Systematic optimization methodologies were utilized to provide for selective adaption of suspension parameters, such as spring constant (rate) and damping coefficient, according to different road surface conditions, including harmonic and stochastic waveforms. By maximizing the average of power generation or minimizing the root-mean-square of the sprung mass’s absolute acceleration by selecting optimal parameters, the suspension allowed operation in either energy-oriented mode or control-oriented mode. Furthermore, a bandwidth enhancement technique utilizing cubic nonlinearities was demonstrated to improve the energy harvesting capability of the suspension system. A self-powered regenerative Skyhook control strategy was proposed to overcome the trade-off between passive control (insufficient control) and active control (external energy demand) for the suspension system.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Farid Golnaraghi
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Noise Measurement in Microsensor Applications

Author: 
Date created: 
2016-08-25
Abstract: 

In this research, spectral coherence noise measurement technique is used to measure noise of capacitive accelerometers, based on measuring the spectral coherence and outputs of two identical sensors exposed to the same input stimulus. This effective technique can be applied to any sensor characterization problem where there is interest in distinguishing instrumental noise from background noise. The simulation study has been done in MATLAB to verify the proposed method reliability to calculate contributions of different noise sources in a system. To verify effectiveness and accuracy of the proposed technique in practical systems, we continue our research in experimental work, using this method on a commercial accelerometer. Then, the technique is applied to measure noise of microsensor systems which consist of MEMS capacitive accelerometer followed by low-noise interface electronics. The proposed technique is also used to measure and quantify the noise contribution of different stages of interface electronics. Experimental results are compared to either reported data on the used devices datasheet, analytical equations, or simulation results. The similarity between experimental results with theoretical values and simulation results verifies the measured noise for microsensor systems. Thanks to spectral coherence noise measurement technique, we will be able to characterize noise behavior of fabricated sensors and reader boards, and determine the lowest noise sensor and interface electronics.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Behraad Bahreyni
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Static and Dynamic Modeling and Simulation of the Umbilical Cable in A Tethered Unmanned Aerial System

Author: 
Date created: 
2016-06-27
Abstract: 

The research at hand has been accomplished in collaboration with our industry partner, Rigid Robotics Inc. and aims to predict and suggest solutions for some of the known and unknown issues that might appear in operation of a tethered Unmanned Aerial System (to be referred to as UAS hereafter). In this work, the static and dynamic behaviour of the power cable connecting a hovering UAS to its base station is studied in different flight scenarios. The mathematical modelling of the cable is carried out using catenary equations for the static case and multi-body dynamics principles are employed for the dynamic condition. In the preliminary stages of the project, for the purpose of the cable and UAS design, a simple technique is used to estimate the maximum tension forces present in the static state of the cable as well as the cable shape function and other related parameters when UAS is in hovering mode. The derivation of the system’s equations of motion is done using Lagrange’s Equations by considering the cable as a discrete multi-body system. The equations of motion are derived for a system of finite segments and are solved numerically using MATLAB™ software package in order to simulate the cable’s motion. The effect of wind on the dynamics of the cable is also implemented using theoretical methods and simulations. The system’s dynamics is modeled in a planar motion as well as a 3D space in separate chapters.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Siamak Arzanpour
Carolyn Sparrey
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.