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Mechanical Engineering - Master's degree

Mostrando recursos 1 - 20 de 3.636

  1. Material characterization and axial loading response of pouch lithium ion battery cells for crash safety

    Mason, Amber J
    Recent research conducted at MIT's Impact and Crashworthiness Laboratory (ICL) has focused on material characterization of lithium ion battery cell components for use in the development of an accurate and practical computational model intended to predict mechanical deformation and related short circuit behavior of Li-ion battery cells and stacks in real world impact scenarios. In an effort to continue to refine and validate this modeling tool, characterization testing was conducted on battery cell pouch material using uniaxial stress and biaxial punch tests. At the full cell level, hemispherical punch indentation validation testing and internal electric short circuit testing was conducted...

  2. The Shipboard Automatic Watchstander (SAW) : utilization of Nonintrusive Load Monitoring for shipboard automation

    Bredariol, Gregory V
    This thesis presents results from operational testing of Nonintrusive Load Monitoring (NILM) systems aboard active US Coast Guard units. Monitoring the ships' electrical system from centralized power distribution points, data collected by the NILMs provide information for: 1) human activity monitoring, 2) energy score keeping, and 3) condition-based monitoring. This thesis shows results from data gathered over two years from both conventional contact current and voltage sensors and novel "noncontact" sensors. This thesis presents the current state of automation available from NILM systems in marine environment applications.

  3. Uranium extraction from seawater : investigating hydrodynamic behavior and performance of porous shells

    Hamlet, Amanda (Amanda M.)
    As global economies grow and demand more energy, scientists work to develop alternative sources to meet demand. Developing countries, e.g. China and India in particular, will turn to nuclear power to meet their energy needs, increasing demand for uranium. There are enough land-based uranium reserves to cover current demand for about 120 years. However, increasing demand will shorten this estimate and require mines to tap into harder-to-extract reserves resulting in higher prices and greater environmental footprints. An unlimited supply of uranium, roughly 4.3 billion tonnes, is dissolved in the ocean at a concentration of 3 parts per billion. Chemists have...

  4. Optimal staffing recommendation for inbound operations

    Li-Carrillo, Carla (Li-Carrillo Paredes)
    Amazon inbound operations are staffed following a 'staffing-to-charge' model in which labor is planned to match the incoming volume capacity required by the weekly Sales Operations Planning (S&OP) forecast. Staffing-to-charge is a lean model of staffing that attempts to maximize labor utilization by minimizing the possibility of a labor surplus or deficit. However, due to inaccuracies in the S&OP freight forecast, poor visibility into incoming inventory, and last minute staffing changes, it is often the case that labor capacity is not adequately aligned with the actual unit receipts. This leads to additional labor costs and network inefficiencies. This project explored...

  5. Improving production yields in bio-pharmaceutical filter media

    Rautenbach, Jeremy Brian
    This thesis presents methods to identify sources of variation in rolled goods manufacturing by defining the critical input process parameters, and the application of statistical process control. Sources of variation are prioritized according to a process control hierarchy, and reduced or eliminated through iterative cycles of rapid experimentation. This work emphasizes the value of team work, breaking down the organizational barriers between departments, knowledge sharing and the importance of a scientific approach to problem solving. FilterCo manufactures and assembles filter media catering to the ultrafiltration market growing at ~12% over the next five years. In a high growth scenario, production...

  6. Hydrogen production from aluminum-water reactions subject to high pressure and temperature conditions

    Seto, Kelsey C
    Aluminum fuel has become an attractive form of energy storage in recent years as it is both a highly abundant and extremely energy dense material. Research has discovered methods of treating aluminum with liquid metal, enabling the aluminum to produce large amounts of hydrogen when oxidized by liquid water. When this fuel reacts with water, it produces hydrogen, heat, and aluminum hydroxide (Al(OH) 3 ). Although this aluminum fuel has already been integrated into an effective mobile hydrogen production source for hydrogen fuel cells, the system size and weight is restricted by the amount of water that is required to...

  7. Cost-optimal design of a household batch electrodialysis desalination device

    Shah, Sahil R
    This thesis investigates the pareto-optimal design of a household point-of-use batch electrodialysis (ED) system to provide a cost-effective replacement for existing reverse osmosis (RO) devices, for brackish water desalination of Indian groundwater, at lower energy consumption and higher recovery: 80-90% vs 25-40%. Target specifications derived from user-interviews, and RO products, guided the selection of a batch architecture, for which a coupled flow-mass transport model to predict desalination rate was developed, and validated using a lab-scale ED stack. The effects of varying the production rate (9-15 L/hr) and product concentration (100-300 mg/L) requirements on optimal selection of geometry, flow-rates, and applied...

  8. Measuring single-cell density using serial suspended microchannel resonators

    Stockslager, Max A
    Cells adjust their composition during important physiological processes, including cell cycle progression, apoptosis, and disease. Due to differences in the densities of water and the various macromolecules which compose cells, changes in cellular composition are reflected by changes in cell density. Previously, methods have been described for measuring density at the single-cell level using suspended microchannel resonators by weighing the same cell in fluids of different densities. Here we describe a high-throughput version of this approach, in which cells are weighed sequentially in three cantilevers containing fluids of different densities. The system design and operation are described, measurement uncertainty is...

  9. Interference and Transmission of locally forced internal waves in non-uniform stratifications

    Supekar, Rohit B
    Several studies have investigated the effect of constructive or destructive interference on the transmission of internal waves that propagate through non-uniform stratifications. Such studies have been performed for internal waves that are spatiotemporally harmonic. To understand the effect of spatiotemporal localization, this thesis presents a theoretical and experimental study of the transmission of two-dimensional internal waves that are generated by a boundary forcing that is localized in both space and time. This is done by considering an idealized problem and applying a weakly viscous semi-analytic linear model to it. After validation with a numerical model, the semi-analytic model allows us...

  10. The assessment of using SI engines for medium-duty applications

    Tang, Gong, S.M. Massachusetts Institute of Technology
    The price of diesel is projected to go up due to increasing demand. The price differential of diesel and gasoline is accordingly projected to increase. As a consequence of the diesel fuel price premium, a diesel engine must be significantly more efficient in terms of gallon/mile or liter/km, just to make up for the higher fuel cost in the US market. In the truck market, the sales of diesel engine share has been going down continuously for class 4 trucks. The decrease may be driven by high diesel fuel prices. This study is to investigate the applicability and economics of...

  11. Fabrication of a nanoporous membrane device for high heat flux evaporative cooling

    Sircar, Jay D
    We investigated the experimental performance of a nanoporous membrane for ultra-high heat flux dissipation from high performance integrated circuits. The biporous evaporation device utilizes thermally-connected, mechanically-supported, high capillarity membranes that maximize thin film evaporation and high permeability liquid supply channels that allow for lower viscous pressure losses. The 600 nm thick membrane was fabricated on a silicon on insulator (SOI) wafer, fusion-bonded to a separate wafer with larger liquid channels. Spreading effects and overall device performance arising from non-uniform heating and evaporation of methanol was captured experimentally. Heat fluxes up to 412 W/cm2, over an area of O.4x 5 mm,...

  12. Optimal shape and motion planning for dynamic planar manipulation

    Taylor, Orion Thomas
    This thesis presents a framework for optimizing both the shape and the motion of a planar rigid end-effector to satisfy a desired manipulation task. We frame this design problem as a nonlinear optimization program, where shape and motion are decision variables represented as splines. The task is represented as a series of constraints, along with a fitness metric, which force the solution to be compatible with the dynamics of frictional hard contact while satisfying the task. We illustrate the approach with the example problem of moving a disk along a desired path or trajectory, and we verify it by applying...

  13. Attitude control via structural vibration : an application of compliant robotics

    Tyrell, Nathan S
    We review and present techniques for effecting and controlling the reorientation of structures "floating" in angular-momentum-conserving environments, applicable to both space robotics and small satellite attitude control. Conventional orientation control methods require either the usage of continuously rotating structures (e.g. momentum wheels) or the jettisoning of system mass (e.g. hydrazine thrusters). However, the systems proposed herein require neither rotating structures nor mass ejection; instead, orientation is controlled by the imposition of a bounded cyclic shape change-the canonical example of such a system is a cat righting herself while falling, thereby always landing on her feet-coupled with the conservation of angular...

  14. Deployment of a passive acoustic detection system for reactive collision avoidance in autonomous underwater vehicles

    Viquez Rojas, Oscar Alberto
    The use of autonomous vehicles in air, land and water has grown in recent years, with increased attention given to heavily transited areas. For the case of autonomous underwater vehicles, these regions of interest include harbors and river basins where the risk of collision rapidly increases with the number of ships. This thesis presents a collision avoidance system based on passive acoustic sensing, which may be used to alert an AUV's autonomy software of the threat that an approaching vessel may represent in such shallow water environments. Experiments were conducted to collect and process data from static and vehicle-mounted hydrophone...

  15. Cost optimization of a solar-powered electrodialysis desalination system

    Watson, Sterling (Sterling Marina)
    With their autonomous operation and low environmental impact, solar photovoltaics (PV) are an attractive power source for off-grid systems. One application of PV is for powering village-scale desalination systems, which are needed in regions with a saline drinking water supply and an unreliable electric grid. However, the intermittent and non-dispatchable nature of solar energy is not well-suited to conventional loads that are designed to operate off of a steady electrical grid, so it is important to design and optimize PV-powered systems such that they are persistent, reliable, predictable, and low-cost. In this thesis, I present a solar photovoltaic-powered electrodialysis reversal...

  16. Two-stage reverse osmosis : optimal element configuration and flux distribution, energy savings

    Wei, Quantum Jichi
    In a two-stage reverse osmosis (RO) system of finite size, there are two degrees of freedom not present in a single-stage RO system: distribution of RO elements between the two stages (system design), and feed pressures (system operation). In this study, we investigate the optimal system design and operation of a two-stage RO system with a mass-balance model and establish a lower bound for the energy savings achieved by the optimized two-stage system compared to a single-stage system. A two-stage RO system may consume more or less energy than a single-stage RO system of the same size and freshwater productivity,...

  17. Microscopic description of the granular fluidity field in nonlocal flow modeling

    Zhang, Qiong, S.M. Massachusetts Institute of Technology
    A recent granular rheology based on an implicit 'granular fluidity' field has been shown to quantitatively predict many nonlocal phenomena. However, the physical nature of the field has not been identified. Here, the granular fluidity is found to be a kinematic variable given by the velocity fluctuation and packing fraction. This is verified with many discrete element simulations, which show the operational fluidity definition, solutions of the fluidity model, and the proposed microscopic formula all agree. Kinetic theoretical and Eyring-like explanations shed insight into the obtained form.

  18. Quantitative biomarkers for tissue characterization

    Zubajlo, Rebecca Elizabeth
    This research proposes and examines noninvasive, quantitative techniques to characterize tissue. The primary metrics investigated include estimation of longitudinal speed of sound and shearwave elastography. Additional metrics investigated include bioimpedance and functional tests specifically for muscle health quantification. Diagnosing and monitoring of health of muscle and liver tissue is the motivating clinical need. These proposed metrics and techniques are noninvasive, quantitative, and do not require calibration. Current standards of care for liver and muscle health include biopsy for liver and muscle or electromyography for muscle. Functional tests, also a gold standard for functional muscle health, are not as quantitative or...

  19. Design and control optimization for high-speed jumping mode Atomic Force Microscope

    Xia, Fangzhou
    In this thesis, I improved the design of a high-speed Atomic Force Microscope (AFM) for jumping mode operation. The relations between important imaging parameters and physical limitations of the system were established first to identify the aspects of improvement. Two control algorithms to improve the imaging speed and probe sample interaction force for jumping mode atomic force microscopy operation have been proposed and investigated both in simulation and experiment. A new generation of multi-actuated sample scanner has been designed to address the dynamic coupling, thermal expansion and range issues in the previous design. Improvements to the optical beam deflection system,...

  20. Load bearing interface design for a pan-tilt mechanism for severe marine environments

    Beautyman, Michael John, Jr
    The Naval Research Laboratory (NRL) requested the design of a two-axis gimbal device for the shipboard support of a sensor payload. Previous design efforts presented a low-mass two-axis (pan and tilt) machine. Vibration and shock testing induced failure in the interface between the payload and the tilt shaft, through which the control cabling connected to the sensors, taking the system out of service and creating a hazard for Sailors. This thesis proposes a tapered, hollowed shaft and flange interface connected by an interference fit that is preloaded and retained by a single hollowed bolt for ease of maintenance at sea....

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