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Mechanical Engineering - Master's degree

Mostrando recursos 1 - 20 de 3.459

  1. Optimizing inventories and standardizing planning procedure in a multipart manufacturing system

    Hua, Yu, M. Eng. Massachusetts Institute of Technology
    This work illustrates how to apply a multi-echelon periodic review base-stock model to a real manufacturing company, Waters Corporation, for their major product Analytical Columns. At Waters, the Analytical Column supply chain ranges from raw materials to the final delivery to customers, and covers US, Europe, and Asia. The goal of this work is to find the best locations to hold safety stock along the supply chain so as to minimize the inventory holding cost for the whole company. To do this analysis, a 5 stage multi-echelon supply chain model is constructed. All the stage costs are measured and standardized...

  2. Product availability improvement for analytical column supply chain : inventory optimization and lot sizing

    Lee, Nelson, M. Eng. Massachusetts Institute of Technology
    This thesis demonstrates the potential of a structured safety stock policy, and an improved lot sizing production policy on the inventory level and service level. The thesis focuses on incorporating demand variability into the factors of determining the safety stock level, and establishing a structured ordering and validation process. The thesis also incorporates setup cost and product nature into creating a new production policy that aims to significantly increase the service level for products in the Build to Order category. A detailed study and interview of the Waters Column Supply Chain are performed at the start of the project leading...

  3. Chamber matching in semiconductor manufacturing using statistical analysis and run-to-run control

    Haskaraman, Feyz
    This thesis focuses on a chamber matching methodology for semiconductor manufacturing in Analog Devices Inc.'s fabrication sites. As ADI extends its efforts to implement Internet of Things and predictive maintenance (PdM) to its fabrication facilities, it is also seeking to increase their overall yield by implementing better monitoring and control of processes and matching the performance of chambers. This thesis project was conducted by F. Haskaraman, T. Nilgianskul and T. Nerurkar as a team to make a series of recommendations to improve process yields using statistical control and to show the benefits of chamber matching in particular. Nilgianskul's thesis focuses...

  4. Creation, validation, and implementation of a Highly Accelerated Life Testing (HALT) procedure to improve the reliability of printed circuit boards

    Singh, Abhishek, M. Eng. Massachusetts Institute of Technology
    Highly Accelerated Life Testing (HALT) is a test methodology to evaluate the reliability of electronic and electromechanical devices. This thesis aimed at the implementation of Highly Accelerated Life Testing (HALT) on Printed Circuit Boards. A standard operating procedure for implementing Highly Accelerated Life Testing (HALT) to increase the reliability of PCBs used in various Waters equipment is developed and validated. For the creation of the standard operating procedure a very reliable Alliance PCB is selected that acts as a benchmark for screening other boards. Extensive testing is done on the Alliance PCB by subjecting it to thermal and vibration stresses...

  5. CFD based design of a high speed planing hull with cambered planing surface, V-step and hydrofoil

    Gray, Calley Dawn
    With emerging applications for high speed boats in commercial, military and off shore industries, there is a focus in the naval architecture community to improve the efficiency and performance characteristics of planing hulls. In the 1960's, Eugene Clement showed that considerable reductions in resistance at high speeds can be obtained by converting a conventional planing hull to a Dynaplane stepped planing hull. A Dynaplane stepped planing hull refers to a hull configuration where the majority of lift is provided by a swept back cambered surface, while the remainder of the lift is provided by an aft lifting surface that also...

  6. A chronically implantable neural device for on-demand microdosing of deep brain structures

    Ramadi, Khalil B. (Khalil Basil)
    Chronic neuropsychiatric diseases are increasingly consuming a larger portion of healthcare costs, in part due to a lack of effective treatment techniques. Through research into the pathology of these diseases we now know that most of these disorders are due to a loss in synchrony in a specific neural network. Effective treatments must seek to attenuate these network dynamics to establish normal neural communication. However, current treatments lack the spatiotemporal resolution to target networks with such specificity. The 'Injectrode' device developed here is a dual-lumen brain probe that is chronically implanted with wirelessly programmable micropumps for drug delivery on-demand. We...

  7. Enhanced condensation with active methods

    Sarathy, Sudarshan
    Condensation of low surface tension fluids is important in liquefied natural gas processing and refrigeration systems. Current state of the art low surface energy low hysteresis coatings are not able to achieve dropwise condensation below 10 mN/m. Surface acoustic waves are proposed as an active method to shed thin condensate films to reduce their thermal resistance and improve heat transfer coefficients. Interdigitated electrode patterns were fabricated on piezoelectric LiNbO3 wafers and SAW waves were generated with RF voltages in the 12.5 - 100 MHz regime. These were tested in the in-house condensation rig with Ethanol, Pentane, Hexane and Perfluorohexane. Heat...

  8. Quality improvement at a semiconductor equipment manufacturing facility through error re-categorization and proper inventory management

    Ismail, Elyud
    This thesis addresses the improvement of first pass yield on the assembly floor of Varian Semiconductor Equipment and Associates (Varian) - a low volume complex semiconductor capital equipment manufacturing facility. First pass yield refers to the proportion of fully built modules that pass testing without the need for additional rework. The first pass yield (FPY) project began in 2011 and showed steady improvement for its first three years. But over the following two years, the primary yield metric has stayed level. The goal of the work presented here is to analyze the reasons for the leveling and propose novel ways...

  9. Production ramp-up of a hardware startup : simulating CONWIP and CONWIP-build to order production strategies

    Jain, Yugal Raj
    When ramping up production volumes, hardware startups are required to identify and tackle obstacles in multiple areas of business including finance, sales, engineering, manufacturing, and servicing. NVBOTS, a Boston based 3D printer manufacturing startup, is going through a similar phase of production ramp-up of its printers. This thesis documents the process that the MIT M.Eng. team went through to identify such obstacles at NVBOTS. This process provides insights into what other startups in similar positions may explore. The topic of manufacturing systems was identified as a potential area of improvement as NVBOTS ramps up its production. Discrete event manufacturing simulation...

  10. Control of a semiconductor dry etch process using variation and correlation analyses

    Nilgianskul, Tan
    Statistical process control (SPC) is one of the traditional quality control methods that, if correctly applied, can be effective to improve and maintain quality and yield in any manufacturing facility. The purpose of this project is to demonstrate how to effectively apply SPC to a dry etch process (in this case plasma ashing), at Analog Devices, Inc., a company that runs large-scale fabrication sites in the Boston area. This thesis focuses on spatial and run-to-run variation across multiple measurement sites on a wafer and validates the assumptions of normality and correlation between sites within a wafer in order to justify...

  11. Design of experiments on a semiconductor plasma ashing process : methods and analysis

    Nerurkar, Tanay Rahul
    Characterizing and controlling process variations in semiconductor manufacturing processes is crucial to ensure the extremely low defect and scrap rates that are needed for semiconductor manufacturing companies to maximize profitability. As semiconductor device critical dimensions become smaller and chips become more complex, and with customers inquiring about process capability metrics to make sure they get the highest quality product, there is a need for chip manufacturers to thoroughly analyze and define their process capabilities. The work in this thesis done in collaboration with Analog Devices Inc., a leading chip manufacturer, shows how the concept of design of experiments (DOE) and...

  12. Production ramp-up of a hardware startup : simulating build to order strategies, capacity estimations and impacts of batching

    Van Grootel, Alexander Willem Anton
    When a startup scales up its enterprise the manufacturing system used to govern the production process should be robust enough to scale up with it. NVBOTS is in a position where it plans to scale up production by an order of magnitude within a few months. NVBOTS's manufacturing systems should therefore be reevaluated to ensure its design will meet requirements. In order to model the production process at NVBOTS a discrete event manufacturing simulation is developed. Both a Push system and a Build to Order (BtO) system are initially considered. The trade-offs that exist in these policies are identified and...

  13. Hydrodynamic performance of multi-component structures in oscillatory flow, from blow-out preventer to dual Cylinder interference

    Fan, Dixia
    As one of the key components for the wellhead integrity, the Blow-out Preventer (BOP) is designed and constructed to prevent abnormal pressure change in the well and keep the blow-out from happening, and therefore is essential for the whole well- being of the offshore drilling system, and this calls for a careful investigation on the understanding of the BOP dynamics and its effect on the whole system. However, due to the complexity of the structure itself, the hydrodynamics of the BOP are difficult to model and therefore is the main focus on this thesis. First a general overview will be...

  14. Electrohydrodynamic (EHD) printing of microparticle streams for additive manufacturing

    Guan, Yue, S.M. Massachusetts Institute of Technology
    Electrohydrodynamic (EHD) printing can be used to fabricate high resolution (~100 nm) features at high rates (~10 kHz), and is compatible with a wide range of materials. However, conventional EHD printing techniques focus only on homogeneously dispersed functional inks, including nanoparticulate materials, molecular and polymers. This thesis explores EHD printing of liquids containing microparticles. For printing, liquids containing microparticles with a diameter of ~1-10 pm are prepared, which sediment upon loading into the capillary tip. A single-tip EHD apparatus enabling pulsed delivery of kilovolt signals, high speed imaging, and measurement of charge transfer to the substrate has been constructed. Using...

  15. Characterization of the exhaust gas condensate pH values of gasoline engines

    Jain, Lakshya
    Exhaust Gas Recirculation has been used in gasoline engines to reduce NOx formation and part-load throttle loss for many years. More recently, there is a trend towards down-sizing and turbocharging engines as the strategy helps to improve fuel economy. Cooled low pressure EGR complements down-sizing-turbocharging in direct injection gasoline engines and has the potential to further improve efficiency. When exhaust gas gets cooled down below its dew point in an EGR cooler, the contained water vapor condenses on the cooler walls and dissolves some of the exhaust gases, which may make the condensate corrosive. For this reason, the extraction point...

  16. Robust motion planning for autonomous tracked vehicles in deformable terrain

    Lee, Sang Uk, S.M. Massachusetts Institute of Technology
    Ensuring the safety of autonomous vehicles during operation is a challenging task. Numerous factors such as process noise, sensor noise, incorrect model etc. can yield uncertainty in robot's state. Especially for tracked vehicles operating on rough terrain, vehicle slip due to vehicle terrain interaction affects the vehicle system significantly. In such cases, the motion planning of the autonomous vehicle must be performed robustly, considering the uncertain factors in advance of the real-time navigation. The primary contribution of this thesis is to present a robust optimal global planner for autonomous tracked vehicles operating in off-road terrain with uncertain slip. In order...

  17. Methods to measure and relate the viscoelastic properties of brain tissue

    Mijailovic, Aleksandar S
    Measurement of brain tissue elastic and viscoelastic properties is of interest for modeling traumatic brain injury, understanding and creating new biomarkers for brain diseases, improving neurosurgery procedures and development of tissue surrogate materials for evaluating protective strategies (e.g., helmets). However, accurate measurement of mechanical properties of brain tissue is challenging due to the high compliance and complex mechanical behavior of this tissue, including nonlinear viscoelastic behavior, poroelastic deformation, and failure mechanisms. Thus, reported measurements of the elastic and viscoelastic moduli of brain tissue vary by several orders of magnitude. This thesis highlights three mechanical characterization techniques for brain tissue: rheology,...

  18. Agile quadrotor maneuvering using tensor-decomposition-based globally optimal control and onboard visual-inertial estimation

    Riether, Fabian
    Over the last few years, quadrotors have become increasingly popular amongst researchers and hobbyist. Although tremendous progress has been made towards making drones autonomous, advanced capabilities, such as aggressive maneuvering and visual perception, are still confined to either laboratory environments with motion capture systems or drone platforms with large size, weight, and power requirements. We identify two recent developments that may help address these shortcomings. On the one hand, new embedded high-performance computers equipped with powerful Graphics Processor Units (GPUs). These computers enable real-time onboard processing of vision data. On the other hand, recently introduced compressed continuous computation techniques for...

  19. Wheel design optimization for locomotion in granular beds using resistive force theory

    Slonaker, James (James C.)
    Inspired by hypotheses of Resistive Force Theory, a general dimensionless form for granular locomotion has been discovered, which instructs how to scale size, mass, and driving parameters to relate dynamic behaviors of different locomotors in the same granular media. These scalings are experimentally confirmed with wheel pairs of various shapes and sizes under many driving conditions in a common sand bed. How the relations may be derived alternatively by assuming Coulombic yielding and how the relations can be augmented to predict wheel performance in different ambient gravities is also explained. Next, a rotating-flap wheel that consists of a central hub...

  20. Designing metal grid contacts for four-terminal tandem solar cells

    Sofia, Sarah E. (Sarah Elizabeth)
    Flat-panel tandem solar cells have demonstrated the potential to exceed the efficiencies of their single-junction constituents. However, robust rules for tandem solar cell design are currently lacking, slowing the development of cost-effective implementations of this technology. The four-terminal (4T) architecture stacks electrically independent sub-cells and avoids current-matching losses, resulting in two main advantages over the conventional integrated two-terminal (2T) architecture: a higher energy yield and a loosened constraint on material bandgap combinations. Because both sub-cells are contacted independently in a 4T tandem, multiple stacked semi-transparent contacts are needed, causing significant shading and series resistance losses. Moreover, for stationary flat panel...

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