Recursos de colección

DSpace at MIT (96.447 recursos)

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Mechanical Engineering - Master's degree

Mostrando recursos 1 - 20 de 3.473

  1. Quality improvement, inventory management, lead time reduction and production scheduling in high-mix manufacturing environments

    Daigle, Sean (Sean Michael)
    This thesis is a compilation of the analysis and recommendations gathered from two industry projects conducted at Applied Materials Varian Division in Gloucester, MA and at the MIT Lincoln Laboratory in Lexington, MA. This thesis addresses the improvement of a quality metric used at Applied Materials through the means of material shortage reduction and lead time reduction of system sub-assemblies. Manufacturing quality was found to be impacted by material shortages across the facility and capacity constraints in an area of the facility that manufactures equipment subassemblies. Implementing a new inventory policy would result in an expected 74% to 80% reduction...

  2. Material characterization of Li-ion battery segments subjected to lateral compression and an in-plane tension loads

    Hakoon, Sagy
    In the last two decades, Lithium-ion (Li-ion) batteries have become an inherent part of day-to-day life thanks to their widespread use in many consumer products and electric vehicles. While these batteries possess great advantages, they also carry an inherent safety liability: In case of a crash event, short-circuit failure of the battery may develop, leading to thermal runaway, fires and even explosions. Hence, a comprehensive study is required, aimed to modulate these batteries and optimize their testing standard. The objective of this research was to characterize the effect of lateral compression on the in-plane tensile failure load of Li-ion battery...

  3. Electrode arrays, test fixture, and system concept for high-bandwidth capacitive imaging

    Hamer, Tyler Thomas
    Spot defects are a leading source of failure in the fabrication of integrated circuits (ICs). Thus, the IC industry inspects for defects at multiple stages of IC fabrication, especially the fabrication of IC photomasks. However, existing non-invasive imaging methods cannot image a modern photomask in a reasonable time-frame. Electroquasistatic (EQS) sensors are arrays of electrode pairs that capacitively couple to targets they sweep over. Utilizing high measurement frequencies and a number of parallel scanning electrode pairs, EQS sensors have been suggested as a potential high speed alternative for defect detection in IC fabrication. This thesis continues the investigation into EQS...

  4. A study of the friction (piston-liner interaction) in internal combustion engines using a Floating Liner Engine

    Vaish, Sarthak
    With the increasing interest in decreasing the environmental impact from internal combustion engines as well as increasing the fuel efficiency has led to deeper investigation into the components of the engine. The mechanical friction in an engine is a major concern, any improvements or reductions in friction can have large implication on the' efficiency of the engines. This thesis focuses on the piston/ ring pack assembly and its contribution to friction. It investigates several key components and trends in friction for the piston/ ring pack assembly, specifically the trends related to the oil control ring and the liner surface. The...

  5. Wave energy converter design via a time-domain Rankine panel method

    Seixas de Medeiros, João
    Efficient design of energy converters heavily depends on the capacity of the designer to accurately predict the device's dynamic, which ultimately leads to the power extraction. This is specially true for wave energy converters (WEC), which usually present a high cost per kWh generated. In this thesis a particular WEC which uses a rotating mass for power extraction is studied. A numerical model for the prediction of its motion and power extraction is presented. The nonlinear dynamic model consists of a time-domain three dimensional Rankine panel method coupled, in the time integration, with a MATLAB algorithm which solves for the...

  6. High temperature annealing for structural optimization of silica aerogels in solar thermal applications

    Strobach, Elise
    Optically transparent, thermally insulating monolithic silica aerogel, with its high solar transmittance and low thermal conductivity, is well-suited for solar thermal applications, particularly concentrated solar power systems. The properties of silica aerogel are directly determined by the structure of the highly porous, interconnected silica network. By using high temperature annealing to control this structure post-synthesis, we were able to optimize the material to increase solar transmittance using an easy and scalable method. The changes caused by annealing were investigated with respect to both temperature and time to relate the structural change to the optical and thermal performance change. The temperature...

  7. Synthesis and electrochemical characterization of carbon nanotube forests on metal foils for battery electrodes

    Lettiere, Bethany R
    Lithium ion batteries (LiBs) are attractive because of their light weight, large specific energy and long cycle life. Lithium ion batteries are typically a planar design where electrode films are manufactured on metal foils and assembled with an ion-conducting separator. The short diffusion length between electrodes in these thin film configurations increases the power density, but reduces the energy density per footprint. There is a need for increasing energy density per footprint to allow for device minimization. 3-dimensional (3D) batteries offer a solution to this problem by creating battery electrodes that have active materials configured perpendicular to the footprint of...

  8. Stability and maneuvering of hybrid hydrofoil/SWATH in foilborne mode

    Williams, Samuel E. (Samuel Ernest)
    The hybrid hydrofoil/SWATH, designed and patented by Stefano Brizzolara, is a novel vehicle design that is optimized to operate in both a high speed foilborne mode and a displacement mode. The retractable hydrofoils on the vehicle take on a unique four surface piercing anhedral foil configuration. This foilborne design is previously unassessed for stability and maneuvering characteristics. A six degree of freedom model of the foilborne vehicle dynamics is introduced as a framework to study vehicle stability and maneuvering. Linearized models of the vehicle dynamics are compared to the six degree of freedom results in both the vertical and horizontal...

  9. Paint-bake effect on the plasticity and fracture of pre-strained aluminum 6451 sheets

    Abi Aki, Rami
    In automotive engineering, sheet metal components are subject to a 20 min heat treatment at 180°C during paint baking. This process may significantly alter the mechanical properties of 6000-series aluminum alloys through artificial ageing. Here, a comprehensive experimental program is carried out to characterize the anisotropic plasticity and the fracture initiation in prestrained artificially-aged aluminum 6451 sheets. It is found that the combination of pre-straining up to 5% strain and heat treatment mainly changes the material's strain hardening behavior and the stress-state sensitivity of its fracture response. The material parameters of the Yld2000-2d plasticity model with combined Swift-Voce hardening are...

  10. A study of node-based finite elements for the solution of the time-harmonic Maxwell equations

    Braun, Michael Rainer
    Classical node-based finite elements are well-known to cause difficulties in the solution of the Maxwell equations. These difficulties are discussed and investigated by means of numerical examples in this thesis. Time-harmonic source problems and eigen-problems are analyzed using mixed node-based finite elements. The results are compared to results obtained with vector finite elements.

  11. Modeling the effects of Reynolds number and added mass on the vortex-induced vibration of drilling risers

    Musser, Chadwyck T. (Chadwyck Terrell), 1975-
    by Chadwyck T. Musser.

  12. Electrostatic loudspeaker design

    Robinson, Thomas Charles
    by Thomas Charles Robinson.

  13. A laser based, non-invasive measurement of blood perfusion

    Martin, Gregory T. (Gregory Thomas), 1966-
    by Gregory T. Martin.

  14. High speed milling of titanium

    Jensen, Jens Thøgersen
    by Jens Thøgersen Jensen.

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

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