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    The design and analysis of asynchronous up-down counters
    (University of Waterloo, 1993-05) Segers, J. P. L.
    The goal of this report is to investigate up-down counter implementations in the framework of delay-insensitive circuits. An up-down counter is a counter on which two operations can be performed: an increment by one and a decrement by one. For N larger than zero, an up-down N-counter counts in the range from zero through N. In the counters we design, the value of the counter, or its count, cannot be read, but it is possible to detect whether the counter's value is zero, N, or somewhere in between. Up-down counters have many applications. For example, they can be useful in implementing queues or stacks. Various implementations for up-down N-counters are presented for any N larger than zero. All counter designs are analyzed with respect to three performance criteria, namely area complexity, response time, and power consumption. One of the designs is optimal with respect to all three performance criteria. Its area complexity grows logarithmically with N, and its response time and power consumption are independent of N.
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    An illustration technique for unstructured 3-D meshes
    (University of Waterloo, 1993-11) Konrad, N. P.; Simpson, R. B.
    Geometric relations in an irregular 3-D polyhedron or tetrahedral mesh are often difficult to comprehend, even for relatively few vertices. A technique for illustrating such meshes which aids this comprehension is described in terms of several independent components, i.e. edge representation, viewpoint and perspective projection, and lighting. These images are suitable for embedding in dynamic displays, or in publications. Heuristics for the effective use of these components are discussed and the technique is demonstrated on three small configurations from the recent literature.
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    Experimental Investigation of Nail Penetration-Induced Thermal Runaway and Particulate Emissions in NMC Lithium-Ion Batteries
    (University of Waterloo, 2026-09-01) Shibu Nair, Ananthu
    Lithium-ion batteries (LIBs) have become a prominent energy storage technology for electric vehicles (EVs), consumer electronics, and stationary energy storage systems due to their high energy density and long cycle life. The growing demand for clean transportation and energy storage has accelerated their widespread adoption. However, this rapid growth has also heightened concerns regarding thermal runaway (TR), a hazardous failure phenomenon in LIBs capable of producing fires, explosions, and the release of toxic gaseous and particulate emissions. Among the abuse tests used to investigate LIB safety, nail penetration (NP) testing is widely employed to simulate mechanically induced internal short circuits (ISCs) within the cell. Despite extensive research, the influence of operating conditions on NP-induced TR behaviour and the characteristics of particulate emissions generated during failure remain insufficiently understood. This thesis experimentally investigates the influence of state-of-charge (SOC) and low-temperature preconditioning on NP-induced TR behaviour of commercially available LG-HG2 (INR18650HG2) LIB cells. Temperature measurements and visual observations were used to evaluate ignition behaviour, thermal response, combustion characteristics, and test repeatability. The TR behaviour of commercially available LIBs with different chemistries and form factors was also compared. Finally, particulate matter (PM) generated during NP-induced TR was characterized using particle size distribution (PSD) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The experimental results demonstrated a strong dependence of TR severity on SOC. Cells tested at 100%, 95%, and 77% SOC underwent immediate TR following NP, whereas the 68% SOC cell did not ignite and exhibited only sustained venting and smoke generation. Low-temperature preconditioning reduced the severity of TR, producing lower peak temperatures and, at −40 °C, delayed ignition in multiple experiments. Comparative testing further demonstrated distinct differences in ignition behaviour, venting characteristics, and combustion response among cells with different chemistries and form factors, emphasizing the influence of battery design on failure behaviour. Post-mortem characterization of TR ejecta revealed that the emitted PM consisted predominantly of submicron particles with spherical, irregular, agglomerated, and flake-like morphologies. SEM-EDX analysis identified carbon-rich particles together with metallic species originating from battery components, while XRD analysis confirmed the presence of crystalline decomposition products associated with cathode materials. These findings contribute to a more comprehensive understanding of NP-induced TR and particulate emissions from LIBs, providing valuable information for battery safety assessment, failure modelling, and the development of safer battery technologies.
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    Toward Automated Tuning and Charge-State Characterization of Accumulation-Mode Silicon Quantum-Dot Devices
    (University of Waterloo, 2026-09-01) Van Osch, Benjamin
    Silicon quantum dots are an exceedingly promising platform for scalable quantum processors, backed by a well-established industry of semiconductor fabrication. Gate-defined processors are limited by the time required to tune, as well as the increasing complexity, scaled by the number of gates in the system. This thesis presents an algorithmic approach for automated tuning as a means of tackling these challenges. Each gate in the dot system represents one additional dimension of the voltage space one must explore to find an optimal operating regime. Including fabrication imperfections and variability, the desirable operating points of the parameter space for a given device are unique and require some time to determine, through multiple avenues of measurement and analysis. The work presented in this thesis advances the group’s current autotuning capabilities, with the partial automatic tuning of a triple quantum dot, accompanied by a charge sensor. This advancement proposes an extension of the previous protocol for use on quantum dots as qubits, as well as an algorithm for automatic calibration and detection of single electron tunneling events by the charge sensor. This algorithm culminates in the automatic measurement of a charge stability diagram. The charge-sensor calibration and initialization of the triple dot system completed successfully in 20 of 20 runs, with a typical runtime of approximately 8.5 hours. The automatic charge stability diagram measurement was successful for one of the two pairs of double dots, with a typical runtime of 7 hours in total. Additionally, this work proposes algorithmic approaches for gate virtualization and identification of specific charge states for the triple dot and charge sensor system. This approach was applied and demonstrated on non-virtualized charge stability diagram data, and successfully detected all visible charge transitions from the measured data. Finally, this thesis demonstrates the manual measurement of bias triangles, as well as proposes a method for automatic detection of Pauli spin blockade, using bias triangles, though the results were inconclusive. These algorithms would allow for focus on the development of readout methods, qubit characterization, and quantum gate and circuit implementations. The algorithms require a priori knowledge of the device and thus are limited in their immediate application to quantum dot devices as a whole. However, these advancements serve as a strong stepping stone towards a more general autotuning protocol. The work in this thesis is therefore applicable to many subsequent quantum dot experiments the group will undertake.
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    Environmental and Economic Trade-offs of Concrete Reuse in Structural Applications
    (University of Waterloo, 2026-09-01) Begeyev, Rustem
    The construction industry is a major source of greenhouse gas emissions, resource consumption, and construction and demolition waste. Structural concrete reuse offers an alternative to demolition and recycling by preserving the embodied value of existing components. However, its practical application depends not only on environmental benefits, but also on technical recovery conditions, logistics and direct construction costs. This research develops a deterministic framework for evaluating the technical, environmental, and economic trade-offs of structural concrete reuse. A normalized 10-storey cross-wall building was used to compare four pathways: direct precast reuse, virgin precast construction, virgin cast-in-place construction, and the reuse of saw-cut cast-in-place floor slabs. Recovery assumptions were informed by published reuse projects and the connection conditions of the case-building system. Direct costs were estimated using RSMeans data, while upfront Global Warming Potential was calculated in One Click LCA using a cut-off allocation approach. The direct precast reuse pathway assumes the recovery of 95% of the floor elements and 85% of the wall elements. It produced approximately 251,029 kg CO₂-e, representing a 75.9% reduction compared with virgin precast construction. Its estimated direct cost was approximately $2.25 million, which was 20.4% higher than the virgin precast baseline. This resulted in a Marginal Abatement Cost of approximately $482 per tonne of CO₂-e avoided. The saw-cut cast-in-place pathway assumes reuse of 85% of the floor-slab volume, while the complete wall system and the remaining 15% of the floor are supplied through new cast-in-place construction. This pathway reduced upfront GWP by 52.0% compared with virgin cast-in-place construction. It also reduced direct cost by approximately 2.1%, resulting in a MAC of approximately -$82 per tonne of CO₂-e avoided. The findings demonstrate that structural reuse is not necessarily associated with a uniform cost premium. Its economic performance depends on the recovery method and the virgin structural system used as the baseline. In both circular pathways, the principal environmental benefit resulted from avoiding virgin material production, while transportation, cutting, lifting and preparation created smaller additional impacts. This study concludes that concrete reuse can support construction-sector decarbonization, when recovery potential, connection conditions, logistics, compensatory material requirements and baseline selection are assessed together.