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The Design and Fabrication of a Punch and Die System for 2.008 Thermoformed Parts
No full textAs a student in 2.008, Manufacturing and Design II, our team successfully manufactured 100 identical yo-yos. Although the class is very well structured and the CNC milling, injection molding, and thermoforming in the Laboratory for Manufacturing and Productivity (LMP) were all optimized for the class, the punch and die system was one process that was more tedious than the rest. Punches, a die, and a calibration piece were designed, fabricated, and tested to find the best clearance size and fill in the gap in documentation of punching plastics. A new, working system was successfully fabricated and assembled, and clearance size 5% was determined to have a lower margin of alignment error. The new punch system will be implemented in the LMP and used by 2.008 students.S.B
Combined Steam Power Cycle and Turbofan Engine for Improvement in Aviation Climate Impacts
No full textDespite significant innovations in aviation technology over the last 70 years resulting in enormous efficiency improvement, the rising demand for air travel means that aviation carbon emissions continue to increase each year. The rate of improvement to aircraft propulsion engines is diminishing and additional improvements often add significant engine cost or weight. With the goal of reducing aviation’s contribution to global climate change, future aircraft engine designers must consider concepts that stray from the traditional turbofan engine. In this thesis, I develop an engine cycle model combining the turbofan engine with a steam power cycle and use the model to explore the benefits of applying this concept to aircraft engines. In order to study the impact to engine performance and emissions from adding a steam cycle, the engine model needs to be capable of representing the water phase changes and the heat exchangers required to drive those phase changes. My contribution is the development of such a model – with special attention to the modeling of water properties and phase change of water – which ties heat exchanger models into an engine thermodynamic model. The engine cycle as well as heat exchanger parameters including water-to-air ratio, combustor exit temperature, overall pressure ratio, and water pressure are varied to explore the impact to overall engine performance, including the impact of the added heat exchanger weight. This thesis covers the development and initial testing of this model, which enables future studies in engines with phase changing heat exchangers or water injection with the goal of assisting the search for the future engine technologies that will reduce harmful impacts of aviation while continuing to allow air travel.S.M
Inclusive B-meson flavour-tagging algorithm at LHCb
No full textA new algorithm is developed to identify the flavour of neutral B mesons at production in pp collisions by utilising all tracks from the hadronisation process. The algorithm is calibrated separately for B0 and B s 0 mesons using B0 → J/ψK+π− and B s 0 → D s − π + decays from pp collision data collected by the LHCb experiment at a centre-of-mass energy of 13 TeV. This new algorithm improves the tagging power by 35% for B0 mesons and 20% for B s 0 mesons when compared to the combined performance of the existing LHCb flavour-tagging algorithms
Cholesterol Nanofiber Patches with Sustainable Oil Delivery Eliminate Inflammation in Atopic Skin
No full textAtopic skin is dry and itchy and lacks integrity. Impaired skin barrier results from altered lipid composition of the skin. A crucial skin lipid, cholesterol, provides flexibility and homeostasis of the cell membranes' lipid bilayer. Cholesterol-based creams and natural oils, especially blackcurrant seed oil, are beneficial for skin care as they hydrate the skin and improve its integrity. The major atopic symptom, skin dryness, can be overcome by the application of porous patches enhanced with cholesterol and natural oil. The base of the patches is constructed of polyimide (PI) nanofibers with cholesterol coatings and externally added blackcurrant seed oil. The presence of cholesterol in PI mats hinders the passage of oil through the patches to the skin, resulting in sustained and prolonged skin hydration. The theoretical and numerical investigations of oil dynamics in porous mats confirmed the experimental results, showing a prolonged skin hydration effect up to 6 h. Additionally, as demonstrated by in vivo tests on atopic mice, cholesterol patches lower serum immunoglobulin E levels and expression of proinflammatory cytokines in the skin, thereby accelerating skin healing. Our results hold great promise for the long-term application of the patches in atopic dermatitis treatment
Propylene Metathesis over Molybdenum Silicate Microspheres with Dispersed Active Sites
No full textIn this work, we demonstrate that amorphous and porous molybdenum silicate microspheres are highly active catalysts for heterogeneous propylene metathesis. Homogeneous molybdenum silicate microspheres and aluminum-doped molybdenum silicate microspheres were synthesized via a nonaqueous condensation of a hybrid molybdenum biphenyldicarboxylate-based precursor solution with (3-aminopropyl)triethoxysilane. The as-prepared hybrid metallosilicate products were calcined at 500 °C to obtain amorphous and porous molybdenum silicate and aluminum-doped molybdenum silicate microspheres with highly dispersed molybdate species inserted into the silicate matrix. These catalysts contain mainly highly dispersed MoOx species, which possess high catalytic activity in heterogeneous propylene metathesis to ethylene and butene. Compared to conventional silica-supported MoOx catalysts prepared via incipient wetness impregnation (MoIWI), the microspheres with low Mo content (1.5–3.6 wt %) exhibited nearly 2 orders of magnitude higher steady-state propylene metathesis rates at 200 °C, approaching site time yields of 0.11 s–1
Time-Marching Quantum Algorithm for Simulation of Nonlinear Lorenz Dynamics
No full textSimulating nonlinear classical dynamics on a quantum computer is an inherently challenging task due to the linear operator formulation of quantum mechanics. In this work, we provide a systematic approach to alleviate this difficulty by developing an explicit quantum algorithm that implements the time evolution of a second-order time-discretized version of the Lorenz model. The Lorenz model is a celebrated system of nonlinear ordinary differential equations that has been extensively studied in the contexts of climate science, fluid dynamics, and chaos theory. Our algorithm possesses a recursive structure and requires only a linear number of copies of the initial state with respect to the number of integration time-steps. This provides a significant improvement over previous approaches, while preserving the characteristic quantum speed-up in terms of the dimensionality of the underlying differential equations system, which similar time-marching quantum algorithms have previously demonstrated. Notably, by classically implementing the proposed algorithm, we showcase that it accurately captures the structural characteristics of the Lorenz system, reproducing both regular attractors–limit cycles–and the chaotic attractor within the chosen parameter regime
Counterfactual Worlds
No full textThis paper extends Kit Fine’s (2012a, 2012b, 2017a, 2017b, 2017c) truthmaker framework to provide a novel task semantics for tensed counterfactual conditionals. Instead of taking possible worlds to be primitive elements in a model, possible worlds will be defined in terms of states, parthood, tasks, and times where the task relation encodes the possible transitions between states. Rather than invoking primitive relations for similarity or imposition, possible worlds will be compared at a time independent of that time’s past and future where the comparison will be carried out in modal and mereological terms. After reviewing motivations for this approach, I will provide the hyperintensional semantics for counterfactuals that is implemented in the model-checker software along with a unified logic for counterfactual, modal, and tense operators. I will then extend the language to include further tense operators in order to analyze forwards, backwards, and backtracking counterfactuals
Efficient Learning and Computation of Linear Correlated Equilibrium in General Convex Games
No full textWe propose efficient no-regret learning dynamics and ellipsoid-based methods for computing linear correlated equilibria—a relaxation of correlated equilibria and a strengthening of coarse correlated equilibria—in general convex games. These are games where the number of pure strategies is potentially exponential in the natural representation of the game, such as extensive-form games. Our work identifies linear correlated equilibria as the tightest known notion of equilibrium that is computable in polynomial time and is efficiently learnable for general convex games. Our results are enabled by a generalization of the seminal framework of Gordon et al. [2008] for Φ-regret minimization, providing extensions to this framework that can be used even when the set of deviations Φ is intractable to separate/optimize over. Our polynomial-time algorithms are similarly enabled by extending the Ellipsoid-Against-Hope approach of Papadimitriou and Roughgarden [2008] and its generalization to games of non-polynomial type proposed by Farina and Pipis [2024a]. We provide an extension to these approaches when we do not have access to the separation oracles required by these works for the dual player. This work will appear in STOC 2025, [Daskalakis et al., 2025].S.M
Report to the President year ended June 30, 2025, Vice President for Resource Development
No full textThis report contains the following sections: Development Planning and Initiatives; Office of Individual Giving; Office of Foundation Relations; Office of Philanthropic Partnerships; Communications, Events, Donor Relations and Stewardship; Strategic Information Management; Human Resources and Strategic Talent Management; and Finance and Operations
Tailoring dynamic hydrogels by controlling associative exchange rates
No full textDithioalkylidenes are a newly developed class of conjugate acceptors that undergo thiol exchange via an associative mechanism, enabling decoupling of key material properties for sustainability, biomedical, and sensing applications. Here, we show that the exchange rate is highly sensitive to the structure of the acceptor and tunable over four orders of magnitude in aqueous environments. Cyclic acceptors exchange rapidly, from 0.95 to 15.6 M−1s−1, whereas acyclic acceptors exchange between 3.77 × 10−3 and 2.17 × 10−2 M−1s−1. Computational, spectroscopic, and structural data suggest that cyclic acceptors are more reactive than their acyclic counterparts because of resonance stabilization of the tetrahedral exchange intermediate. We parametrize molecular reactivity with respect to computed descriptors of the electrophilic site and leverage this insight to design a compound with intermediate characteristics. Lastly, we incorporate this dynamic bond into hydrogels and demonstrate that the characteristic stress relaxation time (τ) is directly proportional to molecular kex