University of Waterloo

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0.42 THz Transmitter with Dielectric Resonator Array Antenna
(University of Waterloo, 2019-07-23) Holisaz, Hamed
Off chip antennas do not occupy the expensive die area, as there is no limitation on their building material, and can be built in any size and shape to match the system requirements, which are all in contrast to on-chip antenna solutions. However, integration of off-chip antennas with Monolithic-Microwave-Integrated Chips (MMIC) and designing a low loss signal transmission from the signal source inside the MMIC to the antenna module is a major challenge and trade off. High resistivity silicon (HRS), is a low cost and extremely low loss material at sub-THz. It has become a prevailing material in fabrication of passive components for THz applications. This work makes use of HRS to build an off-chip Dielectric Resonator Antenna Array Module (DRAAM) to realize a highly efficient transmitter at 420 GHz. This work proposes novel techniques and solutions for design and integration of DRRAM with MMIC as the signal source. A proposed scalable 4×4 antenna structure aligns DRRAM on top of MMIC within 2 μm accuracy through an effortless assembly procedure. DRAAM shows 15.8 dB broadside gain and 0.85 efficiency. DRAs in the DRAAM are differentially excited through aperture coupling. Differential excitation not only inherently provides a mechanism to deliver more power to the antenna, it also removes the additional loss of extra balluns when outputs are differential inside MMIC. In addition, this work proposes a technique to double the radiation power from each DRA. Same radiating mode at 0.42 THz inside every DRA is excited through two separate differential sources. This approach provides an almost loss-less power combining mechanism inside DRA. Two 140_GHz oscillators followed by triplers drive each DRA in the demonstrated 4×4 antenna array. Each oscillator generates 7.2 dBm output power at 140 GHz with -83 dBc/Hz phase noise at 100 KHz and consumes 25 mW of power. An oscillator is followed by a tripler that generates -8 dBm output power at 420 GHz. Oscillator and tripler circuits use a smart layer stack up arrangement for their passive elements where the top metal layer of the die is grounded to comply with the planned integration arrangement. This work shows a novel circuit topology for exciting the antenna element which creates the feed element part of the tuned load for the tripler circuit, therefore eliminates the loss of the transition component, and maximizes the output power delivered to the antenna. The final structure is composed of 32 injection locked oscillators and drives a 4×4 DRAAM achieves 22.8 dBm EIRP.
1,2,3,4
(University of Waterloo, 2018-05-22) Martens, Tess
My thesis exhibition, 1,2,3,4, consists of four performances: Announce It!, A Second Hand Emotion, Slow Change and Portrait-Self-Portrait. The performances will take place on scheduled days at the University of Waterloo Art Gallery throughout the duration of the exhibition. 1,2,3,4, is also a multidisciplinary project, as each performance produces leftovers that will remain installed in the gallery. In addition, the title, 1,2,3,4, references the counting and chanting used in various sporting practice sessions. The installation evolved through the use of remnants of the props, materials and detritus from each performance. The act of preserving the leftovers of each performance serves as both a reminder of each action, as well as a form of documentation. I invite the audience to become witness to, and in some cases also actively participate in my performances. I ask audience members to be a witness to a juxtaposition of empowerment and vulnerabilities within the framework of how I use my body as a tool to produce works. I think of my performances as empowering, comedic, and, at times even tragic. Although these acts are intensely personal, they are open enough to allow witnesses to bring their own experiences to the performances.
1-AMINOCYCLOPROPANE-1-CARBOXYLATE (ACC) DEAMINASE GENES IN RHIZOBIA: ISOLATION AND CHARACTERIZATION
(University of Waterloo, 2007-05-14T13:14:45Z) Duan, Jin
A collection of 233 putative Rhizobia strains from 30 different sites across Saskatchewan, Canada was assayed for ACC deaminase activity, with 27 of the strains displaying activity. When all 27 strains were characterized based on 16S rRNA gene sequences, it was noted that 26 strains are Rhizobium leguminosarum and one strain is Rhizobium gallicum. PCR was used to rapidly isolate ACC deaminase structural genes from the above mentioned 27 strains; 17 of them have 99% identities when compared with the previously characterized ACC deaminase structural gene (acdS) from Rhizobium leguminosarum bv. viciae 128C53K, whereas the other 10 strains are 83% identical compared to the acdS of R. leguminosarum bv. viciae 128C53K. Southern hybridization showed that each strain has only one ACC deaminase gene. Using inverse PCR, the region upstream of the ACC deaminase structural genes was characterized for all 17 strains and shown to encode a leucine responsive regulatory protein. The results are discussed in the context of a previously proposed model for the regulation of bacterial ACC deaminase and facilitates an elaboration of the role of ACC deaminase in nodulation and nitrogen fixation.
10-Year Changes of Food Consumption and Carbon Footprint in Ontario
(University of Waterloo, 2018-06-19) Topcu, Basak
What humans eat can have a significant impact on ecosystems and the climate. In order to attain the climate targets to keep global warming below 1.5 degrees Celsius, it is important to reduce consumption of carbon-intensive food products. Many studies have quantified the environmental impacts of food consumption. However, most of these prior diet-related environmental assessment studies have evaluated impacts based on a snapshot of food consumption, instead of evaluating the changes in food-related environmental impacts over a period of time. Understanding these changes is important in determining what factors affect consumer food consumption behaviours that would shift their food consumption patterns towards less resource intensive products. This thesis evaluates the changes in food, nutritional value, and carbon footprint (CF) of dietary patterns in Ontario in the last decade, broadly in three steps. First, change assessment is conducted by comparing the overall food consumption based on the 24-hour recall food intake data from the Canadian Community Health Survey-Nutrition in 2004 and 2015. Then seven dietary patterns are identified by analyzing the food types of each survey participant and Life Cycle Assessment is used to quantify CF of these dietary patterns. Canada’s Food Guide is used to assess the nutritional quality of actual dietary patterns, and then alternative nutritionally-balanced and low carbon dietary patterns are formulated and their CF is determined. The results suggest that: 1) overall, Ontarians are eating less red meat and more poultry and drinking less beverages high in sugar content; 2) Ontarians continue to overconsume daily protein, possibly because they do not consider protein from non-meat products, such as milk and cheese; 3) the CF of Ontarians food consumption has decreased in the last decade, specifically due to reductions in beef, which is the most carbon-intensive food product; and 4) also, the CF of nutritionally-balanced diets has decreased for all dietary patterns, only exception is Pescatarian that showed a slight increase. Changes in types and amounts of food consumed could be a result of health concerns, increase in climate change awareness, economic or cultural fluctuations. Overall, this thesis improves our understanding of the CF and nutritional assessment of Ontarians’ current food consumption and how this has changed in the last 10 years. By determining and understanding changes, this research could also be helpful to identify strategies to shift Ontarians’ food consumption behaviors towards nutritionally-balanced and low carbon-intensive food choices.
17-21 GHz Low-Noise Amplifier with Embedded Interference Rejection
(University of Waterloo, 2023-01-06) Jodhka, Tejasvi
The ever-growing demand for high performance wireless connectivity has led to the development of fifth-generation (5G) wireless communication standards as well as satellite communication (Satcom). Both 5G wireless communications and Satcom use higher carrier frequencies than traditional standards such as 4G and WiFi. While the higher carrier frequencies allow for larger bandwidths and faster data rates, they come with the cost of high free-space path loss. This high loss necessitates the use of active phased array antennas, which can require hundreds of integrated circuits (ICs) designed in Complimentary Metal-Oxide Semiconductor (CMOS) processes. Furthermore, in a future world with ubiquitous 5G wireless base stations and Satcom users, it is conceivable that Satcom receivers can be jammed by high-power Satcom transmitters and 5G signals. Therefore, Satcom phased arrays must be designed for resilience against these sources of interference while supporting high data rates. One of the key components in a Satcom receiver is the low-noise amplifier (LNA). It is responsible for amplifying the weak, noisy signal received from the satellite into a signal with sufficiently high signal-to-noise ratio for demodulation. One possible solution for making the phased array resilient to sources of interference is to embed filtering in the LNA. This thesis presents two LNA designs that employ embedded filtering for resiliency to interference from 5G wireless signals and Satcom transmitters. First, the circuit-level specifications of a 17.7 - 21.2 GHz (K-band) LNA for satellite communication phased array beamformers are derived from the system requirements. Next, the LNA designs are presented. The first LNA is designed to have out-of-band filtering at 24-30 GHz, which corresponds to the bands containing both 5G and Satcom transmitter interferers. The second LNA is designed to have out-of-band filtering at 27-30 GHz, which addresses a different scenario where the Satcom transmitter is the sole source of interference. Both LNAs are implemented in the Global Foundries 130nm 8XP Silicon-Germanium Bipolar CMOS (SiGe BiCMOS) process. A novel transformer feedback notch is introduced that enhances the filtering capabilities of the amplifier. The full electromagnetic simulation of the first LNA shows a peak gain of 28.8 dB, a minimum noise figure of 1.85 dB, and and input 1 dB compression point (IP1dB) greater than -17 dBm between 24 and 30 GHz. The second LNA shows a peak gain of 27.9 dB, a minimum noise figure of 1.78 dB, and an IP1dB greater than -15 dBm between 27 and 30 GHz. Both LNAs meet specifications sufficient for a Satcom receiver at the same time as having resiliency to out-of-band interference sources.
1b, black legs, 52"
(University of Waterloo, 2021-04-30) Mitchell, Karice
1b, black legs, 52” is an effort to reconcile with history. Through the recontextualization of black pornographic images, this exhibition serves as a re-imagining of what black women’s futures could be. By creating images that are hyper visible in presentation, yet ambiguous in their representation, these works seek to foster images of the black female body that demand to be seen and understood removed from the historical construction of blackness that has been upheld and perpetuated through white supremacy. Giving the black female body a new meaning, we can begin to cultivate new possibilities for it to be understood differently, and for it to exist in its multiplicity. This show creates space for black women and their sexuality to be unapologetically represented, while also allowing ourselves the grace to acknowledge the historical legacy of racism in an effort to subvert it––ultimately, striving towards reclaiming our agency.
1H MAS NMR Study of Water on Pd-MCM-41
(University of Waterloo, 2015-06-18) Crone, Joshua
Hydrogen spillover represents one of the most promising avenues to achieve hydrogen storage at the density required for transportation applications. The spillover phenomenon, however, is a topic of much debate, with many conflicting results existing in the literature. The goal of this work is to thoroughly study and understand a system where spillover has been reported, palladium loaded MCM-41 (Pd-MCM-41), thus laying a groundwork favorable to accurate, conclusive work on the spillover phenomenon in the future. Specifically, the nature of the material and how water (an important factor in certain spillover systems) interacts with it are investigated. This information would not only benefit the study of spillover, but also any other application of Pd-MCM-41 where water is involved. 1H MAS NMR measurements were carried out on three mesoporous silica samples at a range of water hydration levels. The materials were unmodified (pristine) MCM-41, Pd-MCM-41 and reduced (ie. treated with H2 gas) Pd-MCM-41. The spectra from these samples were fit using a previously published model for water on pristine MCM-41, which was extended to account for differences in the current samples. The model was applied first to the pristine MCM-41 spectra. In the hydration range from 0.0 to 0.2 monolayers (ML) of water adsorbed on the pore surface, the results were similar enough to those from Walia's publication that they were used to aid and assess the fitting results of the Pd loaded samples. Additional features observed in the results for pristine MCM-41 were the appearance of a new peak at 0.5 ML, attributed to water condensing and filling sections of the pore volume, and the development of water-water interactions, which are typically absent at lower hydration levels. Two additional peaks, designated Pd Water Groups 1 and 2, are observed in the spectra of the palladized samples. Once these were added to the fitting model, the spectra were determined to be adequately fit by the model; features of the remaining peaks matched those in the pristine sample. Two models, labeled A and B, are presented to explain the differences between the results from pristine MCM-41 and Pd-MCM-41. In Model A, water dissociatively and preferentially adsorbs onto the Pd, causing water to condense around the metal clusters. This multilayer water phase exchanges with water on the pore surface, resulting in Pd Water Group 1. Pd Water Group 2 is attributed to the first layers of water molecules strongly bound to Pd. Model B, which relies on Pd causing nearby water to have a large chemical shift, is shown to be unlikely. The main reason is that the chemical shift of this Pd shifted water is required to increase with increasing water hydration level in order to reproduce the observed chemical shift of Pd Water Group 1. For this and other reasons, Model A is concluded to be the most probable description for the behavior of water on Pd-MCM-41, based on the results presented.
2-Aminopurine-modified DNA homopolymers for robust and sensitive detection of mercury and silver
(Elsevier, 2017-01-15) Zhou, Wenhu; Ding, Jinsong; Liu, Juewen
Heavy metal detection is a key topic in analytical chemistry. DNA-based metal recognition has advanced significantly producing many specific metal ligands, such as thymine for Hg2+ and cytosine for Ag+. For practical applications, however, robust sensors that can work in a diverse range of salt concentrations need to be developed, while most current sensing strategies cannot meet this requirement. In this work, 2-aminopurine (2AP) is used as a fluorescence label embedded in the middle of four 10-mer DNA homopolymers. 2AP can be quenched up to 98% in these DNA without an external quencher. The interaction between 2AP and all common metal ions is studied systematically for both free 2AP base and 2AP embedded DNA homopolymers. With such low background, Hg2+ induces up to 14-fold signal enhancement for the poly-T DNA, and Ag+ enhances up to 10-fold for the poly-C DNA. A detection limit of 3 nM is achieved for both metals. With these four probes, silver and mercury can be readily discriminated from the rest. A comparison with other signaling methods was made using fluorescence resonance energy transfer, graphene oxide, and SYBR Green I staining, respectively, confirming the robustness of the 2AP label. Detection of Hg2+ in Lake Huron water was also achieved with a similar sensitivity. This work has provided a comprehensive fundamental understanding of using 2AP as a label for metal detection, and has achieved the highest fluorescence enhancement for non-protein targets. (C) 2016 Elsevier B.V. All rights reserved.
A 2-Approximation for the Height of Maximal Outerplanar Graph Drawings
(University of Waterloo, 2016-08-18) Demontigny, Philippe
In this thesis, we study drawings of maximal outerplanar graphs that place vertices on integer coordinates. We introduce a new class of graphs, called umbrellas, and a new method of splitting maximal outerplanar graphs into systems of umbrellas. By doing so, we generate a new graph parameter, called the umbrella depth (ud), that can be used to approximate the optimal height of a drawing of a maximal outerplanar graph. We show that for any maximal outerplanar graph G, we can create a flat visibility representation of G with height at most 2ud(G) + 1. This drawing can be transformed into a straight-line drawing of the same height. We then prove that the height of any drawing of G is at least ud(G) + 1, which makes our result a 2-approximation for the optimal height. The best previously known approximation algorithm gave a 4-approximation. In addition, we provide an algorithm for finding the umbrella depth of G in linear time. Lastly, we compare the umbrella depth to other graph parameters such as the pathwidth and the rooted pathwidth, which have been used in the past for outerplanar graph drawing algorithms.
A 2-class maintenance model with dynamic server behavior
(Springer, 2019-04-29) Granville, Kevin; Drekic, Steve
We analyze a 2-class maintenance system within a single-server polling model framework. There are C+f machines in the system, where C is the cap on the number of machines that can be turned on simultaneously (and hence, be at risk of failure), and the excess f machines comprise a maintenance float which can be used to replace machines that are taken down for repair. The server’s behavior is dynamic, capable of switching queues upon a machine failure or service completion depending on both queue lengths. This generalized server behavior permits the analysis of several classic service policies, including preemptive resume priority, non-preemptive priority, and exhaustive. More complicated polices can also be considered, such as threshold-based ones and a version of the Bernoulli service rule. The system is modeled as a level-dependent quasi-birth-and-death process and matrix analytic methods are used to find the steady-state joint queue length distribution, as well as the distribution for the sojourn time of a broken machine. An upper bound on the expected number of working machines as a function of C is derived, and Little’s Law is used to find the relationship between the expected number of working machines and the expected sojourn time of a failed machine when f=0 or f≥1. Several numerical examples are presented, including how one might optimize an objective function depending on the mean number of working machines, with penalty costs attributed to increasing C or f.
2-crossing critical graphs with a V8 minor
(University of Waterloo, 2012-01-17T20:51:50Z) Austin, Beth Ann
The crossing number of a graph is the minimum number of pairwise crossings of edges among all planar drawings of the graph. A graph G is k-crossing critical if it has crossing number k and any proper subgraph of G has a crossing number less than k. The set of 1-crossing critical graphs is is determined by Kuratowski’s Theorem to be {K5, K3,3}. Work has been done to approach the problem of classifying all 2-crossing critical graphs. The graph V2n is a cycle on 2n vertices with n intersecting chords. The only remaining graphs to find in the classification of 2-crossing critical graphs are those that are 3-connected with a V8 minor but no V10 minor. This paper seeks to fill some of this gap by defining and completely describing a class of graphs called fully covered. In addition, we examine other ways in which graphs may be 2-crossing critical. This discussion classifies all known examples of 3-connected, 2-crossing critical graphs with a V8 minor but no V10 minor.
2-Semilattices: Residual Properties and Applications to the Constraint Satisfaction Problem
(University of Waterloo, 2017-08-22) Payne, Ian
Semilattices are algebras known to have an important connection to partially ordered sets. In particular, if a partially ordered set $(A,\leq)$ has greatest lower bounds, a semilattice $(A;\wedge)$ can be associated to the order where $a\wedge b$ is the greatest lower bound of $a$ and $b$. In this thesis, we study a class of algebras known as 2-semilattices, which is a generalization of the class of semilattices. Similar to the correspondence between partial orders and semilattices, there is a correspondence between certain digraphs and 2-semilattices. That is, to every 2-semilattice, there is an associated digraph which holds information about the 2-semilattice. Making frequent use of this correspondence, we explore the class of 2-semilattices from three perspectives: (i) Tame Congruence Theory, (ii) the ``residual character" of the class of 2-semilattices, and (iii), the constraint satisfaction problem. Tame Congruence Theory, developed in [29], is a structure theory on finite algebras driven by understanding their prime congruence quotients. The theory assigns to each such quotient a type from 1 to 5. We show that types 3, 4, and 5 can occur in the class of 2-semilattices, but type 4 can not occur in a finite simple 2-semilattice. Classes of algebras contain ``subdirectly irreducible" members which hold information about the class. Specifically, the size of these members has been of interest to many authors. We show for certain subclasses of the class of 2-semilattices that there is no cardinal bound on the size of the irreducible members in that subclass. The ``fixed template constraint satisfaction problem" can be identified with the decision problem hom$(\mathbb{A})$ where $\mathbb{A}$ is a fixed finite relational structure. The input to hom$(\mathbb{A})$ is a finite structure $\mathbb{B}$ similar to $\mathbb{A}$. The question asked is ``does there exist a homomorphism from $\mathbb{B}$ to $\mathbb{A}$?" Feder and Vardi [22] conjectured that for fixed $\mathbb{A}$, this decision problem is either NP-complete or solvable in polynomial time. Bulatov [15] confirmed this conjecture in the case that $\mathbb{A}$ is invariant under a 2-semilattice operation. We extend this result.
The 2006 Russia-Ukraine Natural Gas Dispute: A mechanisms based approach
(University of Waterloo, 2009-08-26T18:57:05Z) Daley, Stephen
This thesis addresses the factors which lead the Russian government to increase natural gas prices for Ukraine in 2006. Through the use of methodological individualism, an explanation which links system, state, and individual levels of analysis is constructed. The system level variables concerned include global energy prices and the increasing importance of Turkmen natural gas to Russia and other regional gas consumers. State level variables, include changes in Russia’s patrimonial society (changing source of rents, increased authoritarianism); and increasing state control over Russia’s natural gas industry. Changes in these conditioning factors influence individuals’ beliefs about their preferred source of rents, and the nature of their rent seeking and distributing. The resulting actions bring about variations in Russia’s natural gas price for Ukraine. This framework is tested over three time periods (1995-1999, 2000-2004, 2004-2008) selected based on the nature of the conditioning variables over those years. Evidence from these case studies suggests that the above mentioned factors played a large role in the Russian government’s decision. Further, it is concluded that methodological individualism offers a way to bring together system, state, and individual levels of analysis when explaining this event, and perhaps other events in international politics.
The 2009 H1N1 Health Sector Pandemic Response in Remote and Isolated First Nation Communities of Sub-Arctic Ontario, Canada
(University of Waterloo, 2011-05-26T16:43:49Z) Charania, Nadia A.
On June 11, 2009, the World Health Organization declared a global influenza pandemic due to a novel influenza A virus subtype of H1N1. Public health emergencies, such as an influenza pandemic, can potentially impact disadvantaged populations disproportionately due to underlying social factors. Canada’s First Nation population was severely impacted by the 2009 H1N1 influenza pandemic. Most First Nation communities suffer from poor living conditions, impoverished lifestyles, lack of access to adequate health care, and uncoordinated health care delivery. Also, there are vulnerable populations who suffer from co-morbidities who are at a greater risk of falling ill. Moreover, First Nation communities that are geographically remote (nearest service center with year-round road access is located over 350 kilometers away) and isolated (only accessible by planes year-round) face additional challenges. For example, transportation of supplies and resources may be limited, especially during extreme weather conditions. Therefore, remote and isolated First Nation communities face unique challenges which must be addressed by policy planners in order to mitigate the injustice that may occur during a public health emergency. The Assembly of First Nations noted that there has been very little inclusion of First Nations’ input into current federal and provincial pandemic plans. Disadvantaged groups know best how they will be affected by a public health emergency and are able to identify barriers and solutions. Therefore, the objective of my research was to gain retrospective insight into the barriers faced by three remote and isolated First Nation communities of sub-arctic Ontario (i.e., Fort Albany, Attawapiskat, and Kashechewan) during their 2009 H1N1 pandemic response. Culturally-appropriate community-based suggestions for improvement of existing community-level pandemic plans were also elicited. Collected data informed modifications to community-level pandemic plans, thereby directly applying research findings. Being a qualitative community-based participatory study, First Nation community members were involved in many aspects of this research. Semi-directed interviews were conducted with adult key informants (n=13) using purposive sampling of participants representing the three main sectors responsible for health care services (i.e., federal health centers, provincial hospitals, and Band Councils). Data were manually transcribed and coded using deductive and inductive thematic analysis to reveal similarities and differences experienced within and between each community (and government body) regarding their respective pandemic response. Another round of semi-directed interviews (n=4) and community pandemic committee meetings were conducted to collect additional information to guide the modifications to the community-level pandemic plans. Reported barriers due to being geographically remote and isolated included the following: overcrowding in houses, insufficient human resources, and inadequate community awareness. Primary barriers faced by government bodies responsible for health care delivery were reported as follows: receiving contradicting governmental guidelines and direction from many sources, lack of health information sharing, and insufficient details in community-level pandemic plans. Suggested areas for improvement included increasing human resources (i.e., nurses and trained health care professionals), funding for supplies, and community awareness. Additionally, participants recommended that complementary communication plans should be developed. As suggested by participants, community-specific information was added to update community-level pandemic plans. Remote and isolated First Nation communities faced some barriers during their 2009 H1N1 health sector pandemic response. Government bodies should focus efforts to provide more support in terms of human resources, monies, and education. In addition, various government organizations should collaborate to improve housing conditions, timely access to resources, and the level of coordination regarding health care delivery. Furthermore, as pandemic plans are dynamic, government bodies should continue to aide First Nation communities with updating their community-level pandemic plans to satisfy their evolving needs. These recommendations should be addressed so that remote and isolated western James Bay First Nation communities and other similar communities can be better prepared for the next public health emergency.
22-32 GHz Low-Noise Amplifier Design in 22-nm CMOS-SOI Technology
(University of Waterloo, 2019-01-29) Cui, Bolun
This thesis explores the use of a 22-nm CMOS-SOI technology in the design of a two-stage amplifier which targets wide bandwidth, low noise and modest linearity in the 28 GHz band. A design methodology with a transformer-coupled, noise-matching interstage is presented for minimizing the noise factor of the two-stage amplifier. Furthermore, benefits of interstage noise matching are discussed. Next, a transistor layout for minimizing noise and maintaining sufficient electromigration reliability is described. It is followed by an analysis of transformer configurations and a transformer layout example is depicted. To verify the design methodology, two amplifier prototypes with noise-matching interstage were fabricated. Measurement shows that the first design achieves a peak gain of 20.7 dB and better-than-10-dB input and output return losses within a frequency range of 22.5 to 32.2 GHz. The lowest noise figure of 1.81 dB is achieved within the frequency range. Input IP3 of -13.4 dBm is achieved with the cost of 17.3 mW DC power consumption. When the bias at the back-gate is lowered from 2 V to 0.62 V, the power consumption is decreased to 5.6 mW and the peak gain drops down to 17.9 dB. Minimum noise figure increases from 1.81 to 2.13 dB and input IP3 drops to -14.4 dBm. The folded output stage in the second design improves the input IP3 to -6.7 dBm at the cost of 35 mW total power consumption. The peak gain of the second design is 20.1 dB, and the lowest noise figure of 1.73 dB within a frequency range of 23.8 to 32.4 GHz. Both designs occupy about 0.05 mm2 active area.
27 Stories
(University of Waterloo, 2010-05-20T16:30:35Z) Smith, Laura
Invisible Cities is Italo Calvino’s description, in fifty-five stories of fifty-five cities, of the travels of Marco Polo. Each city is fictitious, but collectively they make up Marco Polo’s Venice. A city is distinct; we know Venice (or Manhattan or London) by its buildings, its landmarks, the nature of the city`s fabric, and by the lives of the citizens who gather, work, and live there. As much as the fabric itself, those citizens are unique to the city’s character. The suburbs that developed around major urban centers are not cultural artifacts, built over centuries from traditions and local practices, but products: predictable, marketable en masse, and relatively interchangeable. Conceived of as the ideal blend of city and country, the suburbs are homogeneous, universally accessible, and familiar; so it is with suburban stories. The Stories here are true. The people, places, and events are all real. Isolated, they would be anecdotes, gossip, or reports; in this case, they may be considered postcards – snapshots of everyday life. As a whole they begin to portray the home of millions of people across North America. The twenty-seven stories of this thesis create a window into lives lived in the edge condition called Suburbia.
2D Digital Filter Implementation on a FPGA
(University of Waterloo, 2011-08-31T18:27:59Z) Tsuei, Danny Teng-Hsiang
The use of two dimensional (2D) digital filters for real-time 2D data processing has found important practical applications in many areas, such as aerial surveillance, satellite imaging and pattern recognition. In the case of military operations, real-time image pro-cessing is extensively used in target acquisition and tracking, automatic target recognition and identi cation, and guidance of autonomous robots. Furthermore, equal opportunities exist in civil industries such as vacuum cleaner path recognition and mapping and car collision detection and avoidance. Many of these applications require dedicated hardware for signal processing. It is not efficient to implement 2D digital filters using a single processor for real-time applications due to the large amount of data. A multiprocessor implementation can be used in order to reduce processing time. Previous work explored several realizations of 2D denominator separable digital filters with minimal throughput delay by utilizing parallel processors. It was shown that regardless of the order of the filter, a throughput delay of one adder and one multiplier can be achieved. The proposed realizations have high regularity due to the nature of the processors. In this thesis, all four realizations are implemented in a Field Programming Gate Array (FPGA) with floating point adders, multipliers and shift registers. The implementation details and design trade-offs are discussed. Simulation results in terms of performance, area and power are compared. From the experimental results, realization four is the ideal candidate for implementation on an Application Specific Integrated Circuit (ASIC) since it has the best performance, dissipates the lowest power, and uses the least amount of logic when compared to other realizations of the same filter size. For a filter size of 5 by 5, realization four can produce a throughput of 16.3 million pixels per second, which is comparable to realization one and about 34% increase in performance compared to realization one and two. For the given filter size, realization four dissipates the same amount of dynamic power as realization one, and roughly 54% less than realization three and 140% less than realization two. Furthermore, area reduction can be applied by converting floating point algorithms to fixed point algorithms. Alternatively, the denormalization and normalization stage of the floating point pipeline can be eliminated and fused together in order to save hardware resources.
2D Material Based PTE Detectors with Room Temperature Operations
(University of Waterloo, 2023-12-21) Xie, Zhemiao
Real-time, room-temperature operation and self-powered photothermoelectric (PTE) detection emeries are advanced and versatile solutions for various applications. These detectors offer the advantage of not requiring external power sources, making them portable and suitable for remote or low-power environments. Additionally, their ability to operate at room temperature eliminates the need for costly and complex cooling systems, making them more accessible and cost-effective for various industries and research fields. However, issues of massive fabrication, complicated manipulations, long-term stability, and flexibility are concerned with engaging new exploration on PTE detectors with low-dimensional materials. Two-dimensional (2D) materials are emerging as leading ones due to their broadband detection from Terahertz (THz) to ultraviolet (UV), electrical conductivity with a small band gap, and strong polymer affinity for thermoelectrical conversion. This thesis aims at using 2D nanomaterials of graphene and molybdenum carbide (Mo₂C) MXene for exploring new PTE detectors, guiding 2D materials methodology, leading the investigation of polymer composites, and providing insights into various industrial, imaging, and health monitor applications. This thesis introduces three types of room operation and self-powered PTE architectures with 2D nanomaterials. First, we developed a new doped polyaniline (PANI) as the composite material with a few layers of sheets of graphene. Semi-transparent, broadband infrared (IR) detection and robust flexibility features are presented. Second, a vertical graphene/polyethylenimine (PEI) composite multi-element H-shaped detector with the spray-coating method is presented. High response time, detectivity, and a broadly responsive range are achieved with PEI concentration adjustment, lowering the thermal conductivity and enhancing compacity, focusing the realistic situations with low incident power. Finally, we propose a low-noise PTE device that operates at room temperature by Mo₂C and Poly(3,4-ethylene-dioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS) nanomaterials with a flexible PET substrate. Superior energy conversion and long-term stability of the material and sustainability from surroundings are achieved through material optimizations. Based on such PTE detectors, two promising systems—the motion tracking system and the non-destructive testing (NDT) imaging system—demonstrate the time-tracking of human radiation and high-resolution imaging applications.
3-D Reconstruction from Single Projections, with Applications to Astronomical Images
(University of Waterloo, 2013-08-23T18:52:01Z) Cormier, Michael
A variety of techniques exist for three-dimensional reconstruction when multiple views are available, but less attention has been given to reconstruction when only a single view is available. Such a situation is normal in astronomy, when a galaxy (for example) is so distant that it is impossible to obtain views from significantly different angles. In this thesis I examine the problem of reconstructing the three-dimensional structure of a galaxy from this single viewpoint. I accomplish this by taking advantage of the image formation process, symmetry relationships, and other structural assumptions that may be made about galaxies. Most galaxies are approximately symmetric in some way. Frequently, this symmetry corresponds to symmetry about an axis of rotation, which allows strong statements to be made about the relationships between luminosity at each point in the galaxy. It is through these relationships that the number of unknown values needed to describe the structure of the galaxy can be reduced to the number of constraints provided by the image so the optimal reconstruction is well-defined. Other structural properties can also be described under this framework. I provide a mathematical framework and analyses that prove the uniqueness of solutions under certain conditions and to show how uncertainty may be precisely and explicitly expressed. Empirical results are shown using real and synthetic data. I also show a comparison to a state-of-the-art two-dimensional modelling technique to demonstrate the contrasts between the two frameworks and show the important advantages of the three-dimensional approach. In combination, the theoretical and experimental aspects of this thesis demonstrate that the proposed framework is versatile, practical, and novel---a contribution to both computer science and astronomy.
3-Phenylpyrazino[1,2-a]indol-1(2H)-ones as dual cholinesterase and amyloid aggregation inhibitors
(University of Waterloo, 2017-05-10) Gujral, Sarbjeet Singh
The year 2017, marks the 110th anniversary of the discovery of Alzheimer’s disease (AD)- a devastating neurodegenerative disease. Regardless of the significant advances made in the past century on the pathology of AD, the current pharmacotherapy options for AD remains woefully low and provide symptomatic relief only. Inhibitors of cholinesterase enzymes such as donepezil (Aricept®), rivastigmine (Exelon®) and galantamine (Razadyne®) which represents the primary class of agents used in the management of AD targets one of the many pathological routes of AD. Our study aims at discovering novel small hybrid molecules based on 3-phenylpyrazino[1,2-a]indol-1(2H)-one (PPI) ring system which can potentially exhibit multiple activities toward various factors involved in AD pathophysiology including (i) the inhibition of cholinesterase enzymes such as acetyl (AChE) and butyrylcholinesterases (BuChE); (ii) preventing the aggregation of the neurotoxic amyloid beta (Aβ) peptide and (iii) antioxidant properties. Initial modeling studies suggested that the tricyclic PPI template fits in the catalytic site of AChE and the C3 phenyl can orient toward the peripheral anionic subsite (PAS) in the AChE enzyme. In addition, C3-position provides opportunities to incorporate Aβ binding pharmacophores. With this goal, we synthesized the PPI compound library by coupling ethyl indole-2-carboxylates esters with 2-bromoacetophenones to obtain ethyl-1-(2-oxo-2-phenylethyl)-1H-indole-2-carboxylates which underwent an intramolecular cyclization in the presence of ammonium acetate to afford PPI derivatives (5a-n). The compounds were characterized by analytical methods including NMR and LCMS. The cholinesterase inhibition was evaluated using Ellman’s protocol by UV-Vis spectroscopy. The anti-Aβ-aggregation property was evaluated by fluorescence spectroscopy using thioflavin- T (ThT) assays. Antioxidant activity of the PPI derivatives was assessed using DPPH assay method. Transmission electron microscopic imaging (TEM imaging) were also performed to support the in vitro data obtained from ThT based fluorescence assays. The Discovery Studio (DS) software, Structure-Based-Design program (4.0) from BIOVIA Inc. was used to determine the binding interactions of the PPI derivatives for SAR optimization. Our results indicate that several compounds in the series exhibit dual cholinesterase inhibition properties; one such compound is 5h (3-(2-methoxyphenyl)pyrazino[1,2-a]indol-1(2H)-one) with IC50 AChE = 7.3 μM , IC50 BuChE = 1.9 μM. Compound 5h was found to be much more potent than reference agents donepezil and rivastigmine toward BuChE inhibition. Several other compounds such as 5d ( 3-(3,4-dimethoxyphenyl)pyrazino[1,2-a]indol-1(2H)-one) and 5h (- 3-(2-methoxyphenyl)pyrazino[1,2-a]indol-1(2H)-one exhibited excellent of Aβ40/42 inhibition (% inhibition of Aβ40 = 83.3% and 67.7% at 25 µM respectively, and % inhibition of Aβ42 = 90% and 94% at 25 µM respectively). Compound 5d and 5h were found to be more potent than curcumin and resveratrol towards Aβ42 inhibition. The PPI derivatives were also found to exhibit antioxidant activities. Unsubstituted PPI compound 5a exhibited good antioxidant activity (~33% DPPH radical scavenging at 50 μM), while, compound 5k (3-(4-hydroxy-3-methoxyphenyl)pyrazino[1,2-a]indol-1(2H)-one) exhibited excellent antioxidant activity (~ 84% DPPH radical scavenging at 50 μM). This proves the multi-targeted activities of PPI derivatives. Our results indicate that the fused tricyclic phenylpyrazino[1,2-a]indo-1(2H)-ones (PPI) represent a novel class of compounds which can be modified chemically to design and develop multi-targeting agents aimed at the cholinergic, amyloid cascade and oxidative stress hypothesis of AD.

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