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DSpace at MIT (80,380 recursos)
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Mechanical Engineering - Master's degree

Mostrando recursos 1 - 20 de 3,211

1. Where solar thermal meets photovoltaic for high-efficiency power conversion - Bierman, David M. (David Matthew)
To develop disruptive techniques which generate power from the Sun, one must understand the aspects of existing technologies that limit performance. Solar thermal and solar photovoltaic schemes dominate today's solar market but both bring intrinsic and practical constraints. What will tomorrow's solar market look like? Third generation solar power generation techniques to utilize a larger portion of the solar spectrum are a promising path for high efficiency power generation, but experimental demonstrations remain limited. In this work, the components of a solar thermophotovoltaic power converter are introduced and discussed. While solar thermophotovoltaic devices have the potential to convert sunlight into...

2. Optimizing interventions for the treatment of vascular flow disruptions - Boval, Brett Lawrence
All tissues rely on perfusion and therefore intact blood flow. When flow is disrupted the coupled interaction between the functional and fluid domains of a tissue is impeded and viability is lost. Aortic stenosis is a paradigmatic example of vascular flow disruption. In health there is no gradient across the aortic valve and pressure generated in the left ventricle is transmitted without loss to the aorta. Pressure gradients across the valve force the left ventricle pressure to rise accordingly, straining this proximal pumping chamber, and when it can no longer compensate, affecting distal blood flow and organ perfusion. Aortic stenosis...

3. Tumor cell extravasation in an in vitro microvascular network platform - Chen, Michelle B. (Michelle Berkeley)
A deeper understanding of the mechanisms of tumor cell extravasation is essential in creating therapies that target this crucial step in cancer metastasis. Extravasation assays exist, but with limitations; data from in vivo models are frequently inferred from low-resolution end-point assays while most in vitro platforms are limited in their physiological relevance of the tumor microenvironment. To address this need, we developed a microfluidic platform to study tumor cell extravasation from in vitro microvascular networks formed via vasculogenesis. Various techniques to yield optimal networks were assessed in order to achieve an appropriate balance between vascular growth, remodeling and stabilization. These...

4. Design and implementation of safety control for a class of stochastic order preserving systems with application to collision avoidance near intersections - Mojtaba, Forghani (Forghani Oozroody)
In this thesis, we have designed and implemented a safety control system for collision avoidance near intersections. We have solved the corresponding control problems for a general class of systems that also includes the scenario of the two consecutive vehicles approaching an intersection, which leads to the design of the collision avoidance system. We have gathered the data of behavior of drivers as they approach intersections and have built a stochastic model for that through an optimization problem. The model generates a non-deterministic profile for acceleration of a vehicle which is not equipped with the collision avoidance system and it...

5. Computer assisted design reflection : a web application to improve early stage product in startup companies - Gimenez, Clayton C. (Clayton Christopher)
This thesis investigates the concept of computer-assisted design reflection. The work details the development of a prototype framework and reflection engine. Reflection is a critical process in design. It allows a designer to learn from experience to improve future results. When applied throughout the design process, it can also improve the quality of design decisions as they are made. We have observed that, unfortunately, design teams in startup environments often do not reflect sufficiently, leading to poor results that can cause a company to fail. A computer-assisted system could prompt reflection regularly and also compile responses from designers and users...

6. A grid-level alkali liquid metal battery recycling process : design, implementation, and characterization - Thomas, Dale Arlington, III
The application of liquid metal batteries for large scale grid-level energy storage is being enabled through the development of research conducted at the Massachusetts Institute of Technology (MIT) in 2006. A recycling process to facilitate the end-of-life cycle for alkali or alkaline earth liquid metal batteries was designed, implemented, and characterized through a collaboration between MIT and a battery company. The process developed utilizes recycling methodologies developed and successfully implemented for the recycling of lead-acid and lithium ion batteries. The two methodologies selected for implementation were physical separation and hydrometallurgical material separation. The combination of these two methods results in...

7. Process reengineering for the product development process at an analytical instrument manufacturer - Tandon, Shubhang
In an analytical instrument manufacturing company, the new product development process was analyzed with the objective of reducing time to market, to full scale production of new products and to improve project management and communication in the organization. Several problem areas were identified in the study and the thesis focuses mainly on the systems level changes that the organization would have to make in order to address the identified issues. The problem areas in the organization were the lack of categorization of development efforts, lack of a clear project plan to guide the development effort, functional integration issues and the...

8. The addition of a calender machine to a pyrolytic graphite sheet production plant - Svenson, Ernest Knute
This thesis documents the process and challenges of adding a new calender machine to AvCarb Material Solutions' pyrolytic graphite production plant. Before the machine could be used for mass production, several experiments needed to be conducted to better understand the capabilities of the machine. A process control procedure was designed to set up the machine to produce parts within specification. By using a one-factor-at-a-time approach, the process capability (Cpk) ofthe calender machine can be significantly improved. Additionally, the calender machine was used to investigate the significance of common defects on the uncalendered material. Experiments show that spots that are 3...

9. Assembly lead time reduction in a semiconductor capital equipment plant through constraint based scheduling - Sedore, Blake William Clark
The assembly protocols for a semiconductor capital equipment machine were analyzed for potential lead time reduction. The objective of this study was to determine the minimum assembly lead time for the machine based on the constraints of design, space, and labor availability. An assembly requires the completion of a set of procedures that each contains assembly tasks. Precedence relationships between tasks indicate for each procedure what other tasks must be completed before it can start. Each procedure was assumed to have constant resource requirements throughout its duration. The Critical Path Method (CPM) was used to identify 13 procedures on the...

10. Process reengineering for new product introduction at an analytical instrument manufacturing firm - Ranjan, Aditya
The process of transforming Research and Development knowledge to successfully introducing new products in the market forms a key competency of an innovative company. This new product introduction process was studied at an analytical instrument manufacturing firm. The process of commercialization spanned a number of departments and the process flow lacked functional integration. The current introduction process also lacked a number of management processes, structured feedback loops for information transfer and data metrics for process assessment and evaluation. Due to this, the information related to product knowledge was lost in the process flow creating isolated compartments which was never shared...

11. Efficient scheduling to reduce setup times and increase utilization in a multiple-part manufacturing system - Puszko, Gregory D
Two scheduling procedures were developed to reduce the total setup time and increase utilization in a multiple-part-type manufacturing system with sequence-dependent setups. These scheduling systems focus on reducing setup time by taking advantage of part family setups. A part family is a set of parts that have similar geometries or use the same fixturing or tooling in a flexible machine, thus the labor involved in transitioning between two parts in a family is simpler, and therefore quicker, compared to the average machine setup. One of the scheduling procedures, the setup matrix methodology, was tested through implementation in an actual manufacturing...

12. The value of accurate automated data collection to manufacturing - Perez, Alfonso Alexander
The purpose of this thesis is to demonstrate the value of implementing a novel, accurate automated data collection system and to describe a practical method for doing so. This thesis addresses the value of accurate automated data collection to manufacturing, focusing on a combined passive power monitoring and auto RFID data collection system implemented within the CNC turning and CNC milling departments at the Waters Corporation Machining Center in Milford, Massachusetts. A detailed study of the machining center revealed that inaccurate data was being used to plan production. This thesis demonstrates a graphical approach and an analytical method which can...

13. Pyrolytic graphite production : automation of material placement - Olle, Chase R
This research examines the process and challenges associated with the addition of an autonomous transfer robot to a manufacturing line for AvCarb Material Solutions for use in production of pyrolytic graphite. Development of the system included the design and fabrication of an end-effector, selection of a SCA RA robotic arm, and incorporation of a vision system. The arm and the end-effector were tested to see if material would shift during transfer. The entire system was tested for repeatability and transfer time. The results of the test indicted that the transfer system would successfully meet specifications with high process capability given...

14. Assembly lead time reduction in a semiconductor capital equipment plant through improved material kitting - Jain, Sonam
Manufacturing operations were studied at a semiconductor capital equipment manufacturing plant, with an aim to reduce the production time of their longest lead time module. Preliminary analysis was done by observing the assembly and test operations on the production floor, and material handling operations at the warehouse. Detailed time studies were then performed on the assembly and test processes, to establish baseline measurements and to gather in-depth information on the value added and non-value added activities. It was found that 18% of the assembly activities were non-value added activities, 28% of which were related to material handling on the production...

15. Supplier selection and supplier management improvements at an analytical instrument manufacturing company - He, Yan, M. Eng. Massachusetts Institute of Technology
This thesis addresses the challenges of improving the quality of parts received from suppliers at Waters, an analytical instrument manufacturing company. Preliminary analysis identified improvement opportunities at evaluation of supplier's capability, agreement on requirements with suppliers at early supplier selection stage as well as closed loop supplier management. A 4-step sequential process was designed to improve the supplier selection and management process. First, an initial supplier capability assessment process is incorporated in the quotation process and the Analytical Hierarchy Process is used to make an integrated supplier selection decision. Second, a production part approval process ensures that the supplier fully...

16. Development, implementation and analysis of the first recycling process for alkaline liquid metal batteries - Feldmann, Martin C. (Martin Christopher)
Increasing energy prices, new environmental laws and geopolitical interests demand for new, more efficient and cheaper grid level energy storage solutions. Grid level energy storage refers to large scale energy storage applications that are connected to the power grid. Ambri Inc. is a MIT startup that develops liquid metal batteries for grid level energy storage. Their liquid metal battery operates at elevated temperatures and uses molten metals as electrodes thereby exhibiting a very low fade rate over hundreds of charging and discharging cycles. Ambri cooperated with MIT to develop a new recycling process for their unique battery chemistry to implement...

17. Implementation of automatic inspection system - Chawla, Yugank
Inspection is the formal examination of a product manufactured by any manufacturing process. Inspection process is critical to all the industries as it ensures that a good quality product reach at the end customers. In order to ensure minimum variation in the quality of inspection of a product, industries rely on advanced equipment or gauge to measure the quality parameters of the product. The accuracy of inspection depends a lot on the method and equipments used to inspect a product. However, at AvCarb material solutions, a product called pyrolytic graphite sheet (PGS) is manufactured and at present the types of...

18. Optimizing lot sizes and establishing supermarkets in a multi-part, limited-capacity manufacturing system - Chandar, Arjun Subramani
This thesis addresses the value of optimizing lot sizing to meet part demand within the limits of machine capacity, focusing on a method for improving productivity within the CNC turning and CNC milling departments at the Waters Corporation Machining Center in Milford, Massachusetts. A detailed study of the machining center revealed problems with low machine utilization in turning and milling, low on-time delivery performance and a need for day-to-day adjustments to the production schedule. These problems were attributed to inefficient data collection and use of data, poor production scheduling, and lot sizing that the system's capacity could not handle, causing...

19. Production lead time reduction in a semiconductor capital equipment manufacturing plant through optimized testing protocols - Bhadauria, Anubha Singh
Processes at a semiconductor equipment manufacturing facility were studied with the goal to reduce the production lead time. Based on the principles of lean manufacturing, DMAIC methodology was used to guide the process. Value Stream Mapping (VSM) of the whole process was done to determine that the Universal End Station (UES) was the module with the longest lead time. This work focuses on the optimization of the testing process on the UES. Time studies were conducted for the assembly and test of the UES module and analysis of results revealed a testing process that is serial and thus of a...

20. Natural ventilation in buildings : modeling, control and optimization - Ip Kiun Chong, Karine
Natural ventilation in buildings has the potential to reduce the energy consumption usually associated with mechanical cooling while maintaining thermal comfort and air quality. It is important to know how building parameters, in particular its thermal mass properties and heat loads incurred, affect a building's transient thermal response to incoming outdoor air. A proper ventilation schedule is also needed to make optimal use of the free direct or night cooling. To investigate these factors, a first principles heat transfer energy model is developed to numerically simulate in MATLAB the air temperature profile of a single-zone cross-ventilated room. The physics behind...

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