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‣ A unified approach to modeling, verifying, and improving the manufacturability of mechanical assemblies

Gray, J. Michael (John Michael), 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 282 p.; 1663464 bytes; 1663244 bytes; application/pdf; application/pdf
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The goal of a design engineering organization is to design products that satisfy customers. Reaching this objective is dependent, among other things, on five parameters: the customer expectations, the target percentage of satisfied customers, the nominal performance of the design, the variability in the manufacturing processes, and the sensitivity of the design performance to such variability. This work presents a unified methodology that is amendable to computer implementation for modeling these five parameters for products that are primarily mechanical in nature. The validity of this methodology is subject to five major assumptions: the nominal performance of the design matches the performance expected by the customer, the set of customer expectations can be represented completely by a set of geometric relationships and tolerances between features in the assembly, the degradation in product performance is due solely to quantifiable variability or mean shift in the assembly geometry, the variability in each geometric relationship is independent of the variability in any other geometric relationship, and any compliant parts in the assembly can be accurately modeled as sets of rigid parts connected with linearly-compliant joints. The assembly model is developed using a combination of Screw Theory...

‣ Some trends in the career paths followed by alumni of the MIT Mechanical Engineering Department

Kelly, Catherine A. (Catherine Ann), 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 26 leaves; 2042162 bytes; 2041918 bytes; application/pdf; application/pdf
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by Catherine A. Kelly.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.; Includes bibliographical references.

‣ Lithograph regulation of cellular mechanical properties c by Tsu-Te Judith Su.

Su, Tsu-Te Judith, 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 36 leaves; 2181863 bytes; 2183568 bytes; application/pdf; application/pdf
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A magnetic trap in combination with two-photon fluorescence microscopy was used to determine the cytoskeletal stiffness and three-dimensional (3D) cytoskeletal structure of NIH 3T3 fibroblast cells plated on micropatterned substrates. Microcontact printing of self-assembled monolayers (SAMs) of alkanethiolates on gold was used to create a planar substrate of islands surrounded by non-adhesive regions. The cells were physically constrained within nanometer high adhesive cylindrical posts of defined size on the surface of a titanium and gold coated coverslip. The islands were coated with the extracellular matrix protein fibronectin (FN) and a protein inhibiter was used to restrict cellular extension. After plating, the cells were fixed and stained with phalloidin. A high-speed, two-photon scanning microscope was used to resolve actin architecture in three dimensions and a fractal dimension measurement was performed to quantify the distribution of actin within the cell as a function of adhesion area. The experiments intend to test the hypothesis that cytoskeletal mechanical properties are a function of cellular adhesion area. We further try to understand these mechanical changes by seeking a con-elation between these mechanical parameters and actin stress fiber distribution. It was discovered that the fractal dimension is a weak inverse function of cell adhesion area but that there is a significant change in fractal dimension between patterned and control cells which can freely spread to their natural dimensions. Microrheological experiments using the magnetic trap show that the mechanical properties of patterned cells are similar within statistical error while significantly softer than the control cells.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ Understanding the careers of the alumni of the MIT Mechanical Engineering department

Wolfe, Kristen E. (Kristen Elaine), 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 101 leaves; 5868272 bytes; 5873919 bytes; application/pdf; application/pdf
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This research seeks to understand the careers of MIT mechanical engineering alumni. Data was collected to determine the knowledge and skills that graduates from the classes of 1992 through 1996 make use of in their professions. Data was collected on many topics in four areas: technical knowledge and reasoning, personal and professional skills and attributes, interpersonal skills, and engineering skills. The topics were ranked in terms of expected proficiency, frequency of use, and source of knowledge. The data is presented and implications for improving the mechanical engineering curriculum are discussed.; by Kristen E. Wolfe.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.; Includes bibliographical references.

‣ A common-sense reasoning system for mechanical engineering

Sokoloski, Aaron M
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 64 p.; 2731087 bytes; 2733140 bytes; application/pdf; application/pdf
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This thesis describes the Mechnet system, which was created to test an implementation of analogy-based reasoning about mechanical engineering, focusing on tools and machines that would be found in a shop. Mechnet uses common-sense data about how these things are used and what they are made of, and attempts to judge which objects are similar to each other. The goal was to make "sensible" analogies about things, in that they make sense to a human who has experience in this area. Results show some reasonable analogies for many tools and machines entered, but non-sensical analogies in several instances. The problems which cause these non-sensical analogies are discussed and analyzed. Recommendations are made for improvement; and further research into other kinds of common-sense reasoning.; by Aaron M. Sokoloski.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.; Includes bibliographical references (p. 63-64).

‣ Mechanical and biochemical properties of human cervical tissue

Myers, Kristin M
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 103 leaves
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The mechanical integrity of cervical tissue is crucial for maintaining a healthy gestation. Altered tissue biochemistry can cause drastic changes in the mechanical properties of the cervix and contribute to premature cervical dilation and delivery. This work presents an investigation of the mechanical and biochemical properties of cervical samples from human hysterectomy specimens. Three clinical cases were investigated: non-pregnant hysterectomy patients with previous vaginal deliveries, non-pregnant hysterectomy patients with no previous vaginal deliveries, and pregnant hysterectomy patients at time of cesarean section. Tissue samples for the three clinical cases were tested mechanically and analyzed for biochemical content. Tissue samples were tested in confined and unconfined compression, and biochemical assays measured cervical tissue hydration, collagen content, collagen extractability, and sulfated glycosaminoglycan content. The non-pregnant tissue was found to be significantly stiffer than the pregnant tissue. Collagen extractability was significantly higher in the pregnant tissue. This study represents a first important step towards the attainment of an improved understanding of the complex interplay between the molecular structure of cervical tissue and its macroscopic mechanical properties.; by Kristin M. Myers.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ A thermo-mechanical finite deformation theory of plasticity for amorphous polymers : application to micro-hot-embossing of poly(methyl methacrylate)

Ames, Nicoli M. (Nicoli Margret), 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 217 p.
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Amorphous thermoplastic polymers are important engineering materials; however, their nonlinear, strongly temperature- and rate-dependent elastic-visco-plastic behavior has, until now, not been very well understood. The behavior has previously been modeled with mixed success by existing constitutive theories. As a result, there is currently no generally agreed upon theory to model the large-deformation, thermo-mechanically coupled, elasto-visco-plastic response of amorphous polymeric materials spanning their glass transition temperatures. What is needed is a unified constitutive framework that is capable of capturing the transition from a visco-elastic-plastic solidlike response below the glass transition temperature, to a rubbery-viscoelastic response above the glass transition temperature, to a fluid-like response at yet higher temperatures. We have developed a continuum-mechanical constitutive theory aimed to fill this need. The theory has been specialized to represent the salient features of the mechanical response of poly(methyl methacrylate) in a temperature range spanning room temperature to 60C above the glass transition temperature #g 110C of the material, in a strain-rate range of 10-4/s to 10-1/s, and under compressive stress states in which this material does not exhibit crazing. We have implemented our theory in the finite element program ABAQUS/Explicit. The numerical simulation capability of the theory is demonstrated with simulations of the micron-scale hot-embossing process for manufacture of microfluidic devices.; by Nicoli Margaret Ames.; Thesis (Ph. D.)--Massachusetts Institute of Technology...

‣ Design Squad seasons 1 and 2 : an engineering perspective; Design Squad seasons one and two : an engineering perspective

Powers, Benjamin G. (Benjamin George), 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 208 p.
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This thesis describes the engineering tasks associated with production of Design Squad, a reality-based television program on WGBH. In Design Squad a client gives two teams of high school students an engineering design task for them to complete over two days of building. In order to facilitate production of this program an extensive amount of engineering preparation work is required. Tasks for each episode include concept brainstorming, prototyping of challenge solutions, material procurement, and on-set mentoring. These development and preparation activities require creative brainstorming, teamwork, and communication across a multi-disciplinary team. The MIT based engineering support team has created methods and guidelines to ensure efficient knowledge generation during prototyping that utilize sample builds, proofs of concept, and sketching. Techniques have also been developed for mentoring and guiding the cast members on set. Additionally, a wiki-based communication, tracking, and documentation tool was created to aid in the development process.; by Benjamin Powers; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.; Includes bibliographical references.

‣ Summary of Research 1996, Department of Mechanical Engineering

Faculty of the Department of Mechanical Engineering, Naval Postgraduate School
Fonte: Office of the Associate Provost and Dean of Research, Naval Postgraduate School. Publicador: Office of the Associate Provost and Dean of Research, Naval Postgraduate School.
Tipo: Relatório
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The views expressed in this report are those of the authors and do not reflect the official policy or position of the Department of Defense or the U.S. Government.; This report contains summaries of research projects in the Department of Mechanical Engineering. A list of recent publications is also included which consists of conference presentations and publications, books, contributions to books, published journal papers, technical reports, and thesis abstracts.

‣ Summary of Research 1997, Department of Mechanical Engineering

Faculty of the Department of Mechanical Engineering, Naval Postgraduate School
Fonte: Office of the Associate Provost and Dean of Research, Naval Postgraduate School. Publicador: Office of the Associate Provost and Dean of Research, Naval Postgraduate School.
Tipo: Relatório
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The views expressed in this report are those of the authors and do not reflect the official policy or position of the Department of Defense or the U.S. Government.; This report contains summaries of research projects in the Department of Mechanical Engineering. A list of recent publications is also included which consists of conference presentations and publications, books, contributions to books, published journal papers, technical reports, and thesis abstracts.

‣ Summary of Research 1998, Department of Mechanical Engineering

Faculty of the Department of Mechanical Engineering, Naval Postgraduate School
Fonte: Office of the Associate Provost and Dean of Research, Naval Postgraduate School. Publicador: Office of the Associate Provost and Dean of Research, Naval Postgraduate School.
Tipo: Relatório
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"The views expressed in this report are those of the authors and do not reflect the official policy or position of the Department of Defense or the U. S. Government.; This report contains summaries of research projects in the Department of Mechanical Engineering. A list of recent publications is also included which consists of conference presentations and publications, books, contributions to books, published journal papers, technical reports, and thesis abstracts.

‣ Summary of Research 2000, Department of Mechanical Engineering

Faculty of the Naval Postgraduate School, Department of Mechanical Engineering
Fonte: Office of the Associate Provost and Dean of Research, Naval Postgraduate School. Publicador: Office of the Associate Provost and Dean of Research, Naval Postgraduate School.
Tipo: Relatório
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The views expressed in this report are those of the authors and do not reflect the official policy or position of the Department of Defense or U.S. Government.; This report contains project summaries of the research projects in the Department of Mechanical Engineering. A list of recent publications is also included, which consists of conference presentations and publications, books, contributions to books, published journal papers, and technical reports. Thesis abstracts of students advised by faculty in the Department are also included.

‣ Y B ME? : an analysis of the status of women in mechanical engineering and the Women's Technology Program as a potential long-term solution; Analysis of the status of women in mechanical engineering and the Women's Technology Program as a potential long-term solution

Chestnut, Christina (Christina Callaway)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 33 leaves
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The issue of the lack of women in the fields of science and engineering has recently received new attention by the scientific and women's studies communities alike. In fields such as Mechanical Engineering there continues to be a marked lack of women, especially when looking at higher levels of academia. One solution that has been suggested is to provide young women with a pre-collegiate introduction to engineering and also to give them opportunities to be in contact with women in the field. The Women's Technology Program (WTP), a summer program for girls who have just finished their junior year of high school, was originally created to help solve this problem in the Electrical Engineering and Computer Science department at MIT. Due to its apparent success in the four years of its existence, it was felt that the development of such a program in the Mechanical Engineering department at MIT might be a worthwhile effort. The WTP in ME will contain an overview of many of the topics of mechanical engineering, with an emphasis on critical thinking and problem solving, two skills that are invaluable to engineers and are rarely taught below the university level.; by Christina Chestnut.; Thesis (S.B.)--Massachusetts Institute of Technology...

‣ Effects of biochemical and mechanical stimulation of articular chondrocytes in collagen-GAG scaffolds : extracellular matrix biosynthesis and scaffold stiffness

Gordon, Timothy D., 1971-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 75 p.; 3586053 bytes; 3593813 bytes; application/pdf; application/pdf
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As the incidence of osteoarthritis and other degenerative joint conditions continues to grow, rehabilitation via tissue engineering is becomingly increasingly attractive as an alternative to traditional surgical interventions. Chapters 2 and 3 of this thesis are specifically concerned with cartilage tissue engineering, while chapter 4 is relevant to bone and osteochondral tissue engineering. The cartilage tissue engineering sections focus on the effects of two different classes of regulators of chondrocyte behavior: chemical growth factors and mechanical loading. In chapter 2, FGF-2, a chemical regulator, was supplied to chondrocyte-seeded constructs over a 4 week culture period. Afterward, these constructs were subjected to sequential ramp and hold compressive strains on a Dynastat mechanical testing apparatus, and the unconfined elastic moduli were calculated. These data were compared to the values for scaffolds receiving no FGF. The results indicate that FGF-2 induced a significant increase in the modulus of chondrocyte-seeded scaffolds. Numerous reports indicate that certain types of mechanical loading can increase chondrocytes' ECM biosynthesis in particular cell-scaffold systems in vitro. Few if any loading experiments have been done...

‣ The evolution and evaluation of an interactive engineering design teaching tool : MIT's EDICS; Engineering Design Instructional Computer Program

Jimenez, Craig Edward
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 58 leaves; 2373980 bytes; 2376308 bytes; application/pdf; application/pdf
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For this thesis, I refined and tested a computer-based engineering teaching tool called EDICS. EDICS (Engineering Design Instructional Computer Program) has proven to be a fun and intriguing means of conveying a wide variety of engineering design subjects to undergraduate students. The core audience of EDICS was assumed to be undergraduate engineering students who lacked the practical experience of manipulating common mechanical components and devices. It has been discovered, though, that EDICS is a useful tool for nearly all types of engineering students at many different levels of experience. The testing of EDICS was carried out by having students study either short excerpts from the program or similar subjects covered either in a popular textbook or a booklet, then testing their knowledge retention by subjecting them to a short, written exam. The subjects that were studied were: transmissions, fastening and joining techniques, and engineering drawing and drafting. The results of this evaluation show that in the subjects of transmissions and fastening and joining, students who used EDICS to study performed significantly better than those who studied using paper-based materials. In the subject of engineering drawing and drafting, the students using EDICS scored...

‣ Using a product engineering process to manage an introductory mechanical engineering program

Laskowski, Christina Marie
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 78 leaves; 3777002 bytes; 3780331 bytes; application/pdf; application/pdf
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"Discover Mechanical Engineering" (DME) is a student-run Freshman Pre-Orientation Program at the Massachusetts Institute of Technology which, in the time since its inception in 2002, has developed into a popular, professional, and well-organized pre-orientation program MIT. Yet despite its success, it routinely experiences difficulties with respect to personnel and timeframes, both of which continually threaten the well-being of the program. It appears, however, that such difficulties are not a result of the students' motivational level, since all of DME's student volunteers contribute a great deal of time to the program. Rather, the problem may be that DME student leaders (and their supporting volunteers) are attempting to run the program prior to having taken MIT's Product Engineering Process course (also known as 2.009), a required senior-year mechanical engineering course which is expressly designed to teach students how to manage projects similar to DME. This course teaches tools most useful for the management of personnel and of time - the very areas which DME seeks to improve - through the use of Gantt charts, delineation of the project's critical path, and sundry other methods.; (cont.) It is reasonable to believe that bringing a Product Engineering Process methodology to DME would help rectify existing problems...

‣ Handling hovercrafts : designing a project curriculum to introduce girls to mechanical engineering; Designing a project curriculum to introduce girls to mechanical engineering

Yang, Sandie (Sandie S.)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 23 p.
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The Women's Technology Program was created in MIT's Electrical Engineering and Computer Science department to expose girls to engineering topics and to encourage them to choose engineering majors in college. For the upcoming launch of a WTP in the mechanical engineering department, a new curriculum is being developed. The objective of this research was to create a capstone design project for the WTP-ME curriculum that sparks high school girls' interest in design and manufacturing. A hovercraft design contest was chosen as the basis for the project because of the range of concepts it encompasses and because the competitive nature of the project would encourage cooperation and motivation among the students. To test the project's feasibility, several hovercrafts were built using different materials and geometries. A list of materials was created and contest rules were constructed based on the results, and one hovercraft design was selected to be used as a template hovercraft for the students.; by Sandie Yang.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.; Includes bibliographical references (p. 16).

‣ Designing episode content for Design Squad, a new educational engineering children's television program : the human powered water pump as a design challenge

Sadler, Joel A; Tomczak, Mika A
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 55 p.
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In recent years, problems have emerged in the realm of engineering and engineering education in the United States. Technology literacy is low, there are insufficient numbers of engineering students, and there are misconceptions surrounding the engineering profession. To remedy these problems, WGBH Boston and MIT have created a reality-style engineering-based television program for 9- to 13-year-old children, entitled Design Squad. One episode of the show will challenge the 8 child contestants to build a human-powered waterslide pump, to be used at a community swimming pool. 'Two potential design solutions are proposed for the design challenge: a ball-and-chain pump and a positive-displacement plunger pump. The design process of each solution and an evaluation of each solution's feasibility are presented. Criteria for a successful episode of the show are discussed in relation to the challenge. Prototype experimentation and analysis suggest that the human-powered waterslide challenge will invoke an engaging episode of Design Squad.; by Joel A. Sadder [and] Mika A. Tomczak.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.; Includes bibliographical references (p. 53).

‣ Investigation of team dynamics and group performance in the product engineering process

Lee, Stephanie K. (Stephanie Kwai Ling)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 19 leaves
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The cultural traits of a project engineering team can strongly influence the performance of its members and the quality of the product. The 2.009 Product Engineering Processes class provides an opportunity for investigating the relationships between group dynamics and performance as the student groups work with customers and advisors on brainstorming, designing, testing and construction a fully-functional mechanical prototype over the course of a semester. Performance was measured as a function of time using information from the class ranking system while each team's cultural traits were measured using two surveys that all students were required to complete. Results of this study revealed that the most influential traits on group performance were task understanding, organization and creativity. Analysis of the survey data showed that feedback and professional communication increased while flexibility decreased as the student groups matured from their initial formative stages into fully defined teams. A comparison of teams with sections that reported polar opposite team dynamics revealed that sections with negative group dynamics performed worse than their positive counterparts, though this trend did not hold in the context of the entire class.; (cont.) Investigation of the dynamic profiles of these teams revealed that organization...

‣ The effects of mechanical coupling on the electrical impedance of MEMS resonators for UHF filter applications

Hohreiter, Luke A. (Luke Alfred), 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 138 p.; 7001221 bytes; 7018634 bytes; application/pdf; application/pdf
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(cont.) This thesis presents finite elements based simulations of electromechanical transfer functions for resonator and filter geometries. These Finite Element Analysis (FEA) simulations are performed using the ANSYS software and demonstrate the significance of mechanical coupling between MEMS longitudinal-mode bar (L-Bar) resonators. An analytical model and equivalent circuit are derived for a single L-Bar resonator. The analytical derivation is validated with an FEA model having the same material parameters and boundary conditions. The center frequency and resonant impedance produced by the FEA model are within 1% of the analytical values. A boundary condition study is undertaken to determine the sensitivity of the L-Bar resonator model to changes in the peripheral geometry and displacement constraints. A comparison of FEA results indicates that a simple resonator model with only tether supports yields impedance and center frequency values comparable to those of more complex geometries. When compared to initial experimental results from an actual resonator, the simulated electrical output corresponds well to the actual transfer function. This study also introduces a method for calculating the parameters of the resonator's equivalent circuit model from simulated (or measured) transfer function data. The method is tested on simulation data for which a mechanical Quality factor is designated. Comparing the prescribed mechanical Q to the extracted circuit Q provides a consistency check for the technique. The parameter extraction technique is a useful first attempt to devise a comprehensive method for determining circuit parameters that will reliably reproduce the transfer function of an actual resonator. Finally...