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‣ A methodology for determining engineering costs and their effects on the development of product families

Johnson, Michael DeShawn, 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 157 p.; 8973018 bytes; 8972826 bytes; application/pdf; application/pdf
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The goal of most firms is to deliver products that satisfy customer needs. Delivering a variety of differentiated products allows firms to satisfy the broadest range of customers. There is, however, a fundamental tension between this product differentiation and product cost. The use of product platforms allows a firm to reduce this tension, offering variety while also benefiting from the economics of mass production for shared components. The selection of components and subassemblies for platforming can have wide ranging effects on both product performance and cost. This thesis addresses the latter by presenting a methodology to assess product development costs, the amount of part sharing in a product family, and the effects of platforming on development, fabrication, and assembly costs for product families. Ordinal metrics are presented to assess the performance of product families. The methodology of process-based cost modeling, used to estimate product fabrication and assembly costs, is also posed. A method for determining the allocation of costs for parts and subassemblies shared among product family variants is outlined. A process-based cost model of the automotive product development process is presented. This model uses product part and subassembly characteristics to estimate the engineering effort required at various stages of the development process. Product development cycle time is also estimated. Linear regression analysis is used to determine which part and subassembly characteristics affect engineering effort. Additional development costs...

‣ Peripheral mechanical loading and the mechanism of abnormal intention tremor

Adelstein, Bernard D
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 190 [i.e. 189] leaves; 8826548 bytes; 8826304 bytes; application/pdf; application/pdf
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by Bernard Dov Adelstein.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Mechanisms in thermal mechanical forming of plates

Malaret, Hiram A. (Hiram Anthony)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 88 leaves; 4252595 bytes; 4252353 bytes; application/pdf; application/pdf
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by Hiram A. Malaret.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering and Dept. of Mechanical Engineering, 1987.; Bibliography: leaves 73-74.

‣ A device for testing the electronic and mechanical properties of conducting polymers with electron paramagnetic resonance spectroscopy

Powley, Nicholas R. (Nicholas Ransom), 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 35 leaves; 2331440 bytes; 2330768 bytes; application/pdf; application/pdf
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Conducting polymers have the potential to serve the technical and commercial communities with novel actuators, sensors, and biomimetic devices. The conjugated structures of these polymers and the addition of dopants enable conduction. [1] One current goal in the conducting polymer field is to observe and understand the events by which these polymers carryout their active mechanical functions (contraction and expansion) upon the application of a potential. This thesis presents the design and a prototype of a new device for investigating the relationship between the mechanical and electronic properties of conducting polymers with EPR Spectroscopy. The performance of the testing device was explored with a controlled experiment. The results of this experiment suggest that the response of conducting polymer actuators to mechanical inputs can be examined with EPR Spectroscopy.; by Nicholas R. Powley.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.; Includes bibliographical references (leaf 35).

‣ Calibration of sonographic gel probe covers for in-vivo mechanical testing

Charenkavanich, Panasaya
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 29 leaves; 1438536 bytes; 1437251 bytes; application/pdf; application/pdf
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Cervical insufficiency is a condition in pregnancy in which the cervix asymptomatically dilates in the absence of uterine contractions, resulting in a spontaneous preterm delivery. The condition is often misdiagnosed and presents a significant challenge for the clinical community. In order to establish better diagnostic criteria for cervical insufficiency and to improve assessment of preterm delivery risk for the individual patient, a non-invasive medical imaging tool, which uses ultrasound elastography to test the mechanical properties of cervical tissue, has been developed. The hand-held ultrasound indentation system will enable in vivo collection of stress-strain data from patients that will provide researchers with the necessary information to be used in material modeling and improve diagnosis of cervical insufficiency. The device consists of an ultrasound probe, enclosed by a gel-filled cover. The mechanical properties of the covers vary with each cap as well as with time and temperature. Therefore, in order to ensure accurate measurement, the probe covers must be calibrated prior to use. An experimental study was carried out to examine the effects of various testing conditions on the mechanical behavior of the probe covers. Different freezing and thawing techniques were explored in order to determine favorable conditions in order to preserve the integrity of the probes between the time of manufacture and actual use. From the results of the research...

‣ An instrument for high-throughput measurements of fiber mechanical properties

Kristofek, Grant William, 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 177 leaves; 8783459 bytes; 9222812 bytes; application/pdf; application/pdf
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In this thesis, an instrument is designed and constructed for the purpose of measuring the mechanical properties of single fibers. The instrument is intended to provide high throughput measurement of single fiber geometric properties, tensile properties, elastic properties, surface roughness properties, friction properties, bending properties, and torsion properties. The instrument is capable of performing all of these mechanical measurements automatically on a large number of sample fibers which are stored in the instrument during testing.; by Grant William Kristofek.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.; Includes bibliographical references (leaves 173-177).

‣ Estimation of nonlinear mechanical properties of atherosclerotic plaques

Zhu, Ting F. (Ting Fredrick)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 91 leaves; 3195834 bytes; 3199589 bytes; application/pdf; application/pdf
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A numerical method has been developed to estimate the mechanical properties of atherosclerotic plaques by combining genetic algorithm with finite element methods. Plaque images derived from optical coherence tomography were employed to construct finite element models which were subsequently used in conjunction with a genetic algorithm to determine the parameters in a nonlinear constitutive model. A new multi-frame scheme is introduced to better perform the estimation on a nonlinear mechanical model and reduce the effects of noise. Results show while it is feasible to estimate the nonlinear mechanical properties of plaque, the accuracy can depend on various factors, especially the noise. KEY woRDS: FEM, atherosclerotic plaques, parameter estimation, Mooney-Rivlin model, optical coherence tomography, image noise.; by Ting F. Zhu.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.; Includes bibliographical references (leaves 57-59).

‣ Multi-axis compliant mechanism-based nanopositioner for multi-mode mechanical testing of carbon nanotubes

Lin, Kevin, S.M. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 147 p.; 6125321 bytes; 6131465 bytes; application/pdf; application/pdf
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This thesis documents the design of a multi-axis nanopositioner that addresses a need for carbon nanotube (CNT) instrumentation that is capable of multiple modes of mechanical testing. This nanopositioner is a solution to the need to quantify the mechanical properties of CNTs with the appropriate modes of testing, such as simultaneous bending and tensile loading. This information is important as it is required to test and better understand the properties of CNTs before and after they are used in micro/nano-structures. The multi-axis nanopositioner will be integrated as one of the core components in a new CNT instrument that is presented in this thesis. The nanopositioner is a compliant mechanism-based device designed that is to induce precise nanometer-level deformations in CNTs within a scanning electron microscope (SEM). The design presented in this thesis is a 4-axis prototype of a 6-axis version. The 4-axis nanopositioner was able to demonstrate over one micron range of motion in multiple axes with 10 nm resolution and repeatability. The nanopositioner was specifically designed to fit inside an SEM like an ordinary sample.; by Kevin Lin.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.; Includes bibliographical references (p. 116-118).

‣ Instrumentation for multiaxial mechanical testing of inhomogeneous elastic membranes

Herrmann, Ariel Marc
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 129 p.; 5158928 bytes; 5164284 bytes; application/pdf; application/pdf
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This thesis presents the design, development, and construction of an instrument for biaxial mechanical testing of inhomogeneous elastic membranes. The instrument incorporates an arrangement of linear motion stages for applying arbitrary deformation profiles on the material under test, purpose-built two-axis force transducers for high-resolution measurement of applied loads, and a digital imaging system for full-field strain measurement. The components described herein provide the foundation for a sophisticated biaxial testing platform for determining the mechanical properties of anisotropic, inhomogeneous membrane materials.; by Ariel Marc Herrmann.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.; Includes bibliographical references (p. 93-100).

‣ Analyzing mechanical and software solutions in their patents

Villarruel, Nicolas R
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 30 leaves
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An analysis of patents was conducted in order to find the motivation and reasons behind selecting either a mechanical or software solution. The reasons for selecting a mechanical solution were claimed to be for simplicity, reliability, and robustness while the reasons for selecting a software solution were for increased performance and flexibility. The three cases evaluated were fuel regulation, power and torque distribution, and engine valve timing. A tendency to use mechanical solutions to provide a simpler and more reliable device was found while software solutions were used when greater performance was desired.; by Nicolas R. Villarruel.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.; Includes bibliographical references (leaf 30).

‣ Using mass media to bring engineering principles to young audiences to inspire interest and pursuit of future engineering or technologically based careers

Straub, Kimberly M; Lentz, Deanna M
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 22 leaves
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In the progression of this thesis document, an idea for an episode of an educational and interactive television show has been explored and developed. The direction of this episode will fit into the aforementioned educational television show format (which will be further described and discussed in subsequent sections of this document). For our particular episode, the focus audience and main target demographic of the theme are young, middle-school aged girls. The theme of the show, which has to do with cooking a familiar and typically well-liked (by children) food by using an alternative energy source and engineering design principles. In this show, it is our goal that both the players and the viewing audience learn about the engineering concepts involved with basic optics and solar energy. In our investigation, a theme for the episode has been developed, and a sample solution has been worked out and tested. Based on the results of this trial run, suggestions and conclusions have been made regarding the future directions for this project.; by Kimberly M. Straub and Deanna M. Lentz.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.; Includes bibliographical references (leaf 22).

‣ Rheology of complex fluid films for biological and mechanical adhesive locomotion

Ewoldt, Randy H. (Randy Harold)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 143 p.
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Many gastropods, such as snails and slugs, crawl using adhesive locomotion, a technique that allows the organisms to climb walls and walk across ceilings. These animals stick to the crawling surface by excreting a thin layer of biopolymer mucin gel, known as pedal mucus, and their acrobatic ability is due in large part to the theological properties of this slime. The primary application of the present research is to enable a mechanical crawler to climb walls and walk across ceilings using adhesive locomotion. A properly selected slime simulant will enable a mechanical crawler to optimally perform while climbing in the horizontal, inclined, and inverted positions. To this end, the rheology of gastropod pedal mucus is examined in greater detail than any previously published work. The linear rheological response of pedal mucus is examined with flow, oscillation, and creep tests. Nonlinear rheology is examined with large amplitude oscillatory shear (LAOS), and analyzed with Lissajous curves, Fourier transform rheology, and a new measure of non-linear elasticity. In addition, pedal mucus is examined with a flexure-based microgap rheometer, which can test the sample at the biologically relevant gap of 10-20lim, the measured thickness of pedal mucus under a crawling slug.; (Cont.) Adhesive locomotion of a mechanical crawler is modeled in order to find the criteria for an optimal slime simulant. After developing the selection criteria for the ideal simulant...

‣ Multiscale micromechanical modeling of the thermal/mechanical properties of polymer/clay nanocomposites

Sheng, Nuo, 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 217 leaves
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Polymer/clay nanocomposites have been observed to exhibit enhanced thermal/mechanical properties at low weight fractions (We) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase "particles"; in particular, the particle volume fraction (f,), the particle aspect ratio (L/t), and the ratio of particle thermal/mechanical properties to those of the matrix. These important aspects of as-processed nanoclay composites require consistent and accurate definition. A multiscale modeling strategy is employed to account for the hierarchical morphology of the nanocomposite: at a lengthscale of thousands of microns, the structure is one of high aspect ratio particles within a matrix; at the lengthscale of microns, the clay particle structure is either (a) exfoliated clay sheets of nanometer level thickness or (b) stacks of parallel clay sheets separated from one another by interlayer galleries of nanometer level height, and the matrix, if semi-crystalline, consists of fine lamella, oriented with respect to the polymer/nanoclay interfaces. Here, quantitative structural parameters extracted from XRD patterns and TEM micrographs (the number of silicate sheets in a clay stack...

‣ High strain rate mechanical characterization of trabecular bone utilizing the split-Hopkinson pressure bar technique

Johnson, Timothy Paul Mahal
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 188 p.
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The split-Hopkinson pressure bar (SHPB) technique has been in use in one form or another for more than fifty years and has recently gained a great deal of attention for its ability to characterize materials such as metals, plastics, and even stiff foams at strain rates of up to 105 sec-1. Historically, however, numerous obstacles have stood in the way of applying this technique to softer biological tissues. This study is aimed at bridging this gap by employing various innovations in the field of split-Hopkinson pressure bar techniques (including hollow aluminum and solid polymeric pressure bars) to the characterization of trabecular bone. A preliminary study is conducted on a polyurea (PU) blend to assess the advantages and shortcomings of these approaches, as well as to validate the results obtained with each. Bovine trabecular bone with marrow in-situ, which was chosen for its ability to be tested with a wide spectrum of techniques, is then characterized with the selected techniques at rates of up to 1300 s-1 and strains of 0.07. The results are presented for each technique in the form of engineering stress vs. engineering strain curves.; (cont.) Average trend curves are also provided. Unfortunately, many of the samples were too damaged to allow for accurate measurement of apparent density. Consequently...

‣ Design and optimization of imaging systems by engineering the pupil function

Bagheri, Saeed, Ph. D. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 159 p.
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It is expected that the ability to accurately and efficiently design an imaging system for a specific application will be of increasing importance in the coming decades. Applications of imaging systems range from simple photography to advanced lithography machines. Perhaps the most important way to make an imaging system meet a particular purpose is to engineer the pupil function of the imaging system. This includes designing a pupil surface and often involves the simultaneous design of a post-processing algorithm. Currently these design processes are performed mostly by using numerical optimization methods. Numerical methods in general have many drawbacks including long processing time and no guarantee that one has reached the global optimum. We have developed analytical approaches in designing imaging systems by engineering the pupil function. Two of the most important merit functions that are used for the analysis of imaging systems are the modulation transfer function (MTF) and the point spread function (PSF). These two functions are standard measures for evaluating the performance of an imaging system. Usually during the design process one finds the PSF or MTF for all the possible degrees of freedom and chooses the combination of parameters which best satisfies his/her goals in terms of PSF and MTF.; (cont.) In practice...

‣ A constitutive theory for the mechanical response of amorphous metals at high temperatures spanning the glass transition temperature : application to microscale thermoplastic forming of Zr₄₁.₂Ti₁₃.₈Cu₁₂.₅Ni₁₀Be₂₂.₅

Henann, David Lee
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 102 p.
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Bulk metallic glasses (BMGs) are a promising emerging engineering material distinguished by their unique mechanical properties and amorphous microstructure. In recent years, an extremely promising microscale processing method for bulk metallic glasses, called thermoplasticforming has emerged. As with any emerging technology, the scientific basis for this process is at present fragmented and limited. As a result their is no generally agreed upon theory to model the large-deformation, elastic-visco-plastic response of amorphous metals in the temperature range relevant to thermoplastic-forming. What is needed is a unified constitutive framework that is capable of capturing the transition from a elastic-visco-plastic solid-like response below the glass transition to a Newtonian fluid-like response above the glass transition. We have developed a finite-deformation constitutive theory aimed to fill this need. The material parameters appearing in the theory have been determined to reproduce the experimentally measured stress-strain response of Zr₄₁.₂Ti₁₃.₈Cu₁₂.₅Ni₁₀Be₂₂.₅ (Vitreloy-1) in a strain rate range of [10-5, 10-1] s-1, and in a temperature range [593, 683] K, which spans the glass transition temperature [nu]9 = 623K of this material. We have implemented our theory in the finite element program ABAQUS/Explicit. The numerical simulation capability of the theory is demonstrated with simulations of micron-scale hot-embossing processes for the manufacture of micro-patterned surfaces.; by David Lee Henann.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ Exciting youth about science and engineering : the Stirling Engine class; Stirling Engine class

Barragán, Patrick R
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 58 p.
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The problem of a lack of science and engineering opportunities for youth has been identified. While other programs and attempted solutions exist, a novel approach involving creating self-contained project classes, called modules, and trading them between institutions is proposed. This idea intends to make these lacking opportunities available while overcoming some of the current problems opposing this availability namely insufficient resources and staff. While limited time and resources prevents the complete testing of the idea, the development of a single module to the point before developing a trading system is implemented. The project chosen is the construction and operation of the Stirling Engine using a design borrowed from MIT course 2.670. The module is tested with 15 4th to 7th grade home-schooled students in Los Angeles, Ca. Observations and participant feedback are gathered. Changes including the shortening of lectures, simplification of the project, and addition of testing are proposed. The information gathered from the test suggests that with a trading system in place, these modules can expose students to science and engineering and generate excitement for the fields.; by Patrick R. Barragán.; Thesis (S.B.)--Massachusetts Institute of Technology...

‣ Diagnostic indicators for shipboard mechanical systems using Non-Intrusive Load Monitoring

McKay, Thomas Duncan
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 100 p.
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This thesis examines the use of Non-intrusive Load Monitoring (NILM) in auxiliary shipboard systems, such as a low pressure air system, to determine the state of equipment in larger connected systems, such as the main propulsion engines. Using data collected on previously installed NILM's at the Naval Surface Warfare Center, Philadelphia DDG-51 Land Based Engineering Site (LBES), major event changes were analyzed and diagnosed using power data collected from the in-service low pressure air compressor (LPAC) and the in-service fuel oil pump. Events investigated include main propulsion engine starts and loadings, gas turbine generators starts, major electrical load shifts, and leak insertions into the low pressure air system. An additional NILM was installed on the General Electric LM2500 Universal Engine Controller (UEC) in order to assist in the diagnosis of various state changes. The UEC provides the appropriate interfaces to monitor and control each LM2500 GTM. The UEC controls the application of starter air, ignition power, and fuel to the engine while also receiving feedback of engine parameters from sensors on the engine. Using the combined data received by the LPAC, fuel oil pump, and UEC, a diagnosis system is derived that can detect major events in the engineering plant described above.; by Thomas Duncan McKay.; Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology...

‣ Fusion of engineering, art, and education through an interactive robotic puppet show

Felix, Heather K
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 11 leaves
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In this current age of the Technological Revolution, technical proficiency is not enough for graduating engineers and scientists. Creativity and innovation need to be emphasized and pursued. The Robotic Puppet Show fuses engineering, art, and education all in one. The focus of the project is to promote not only interest in math and science for young women, but it includes art to develop creative thinking. The robotic puppets are powered by Vex motors and servos and operated by remote control. After construction of a robotic puppet, I visited a Boston area high school as a guest speaker to demonstrate the robotic puppet's features and abilities, to talk about engineering as a student and in industry, and to gain feedback from students. The robotic puppet was well-received. Human interaction with the robotic puppet played a large part in the students interest. Future plans for the Robotic Puppet Show include developing more personable robots that interact with students on stage. Results indicate that there is potential for successfully teaching robotics to students in this art/engineering approach to both encourage women to pursue engineering and to develop creative thinking that is much needed in today's changing job market.; by Heather K. Felix.; Thesis (S.B.)--Massachusetts Institute of Technology...

‣ Design of mechanical testing device to measure break angle of thin, stainless steel

Weiner, Stephen (Stephen Andrew)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 25 leaves; 1481807 bytes; 1480222 bytes; application/pdf; application/pdf
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Working with Gillette Corporation, an automated mechanical testing tool that bent a small flat piece of steel was designed. The design of the tool was an effort to improve upon previous generations of the same tool. It consisted of three main elements; a servomotor, connected to a torque transducer, which was connected to a break device. A thin piece of steel was loaded into the break device and the motor was activated, moving a flipper arm on the device which bent the steel. While bending this piece of steel, the torque transducer would relay torque and angle information to a computer. This information was collected and displayed in Excel as torque versus angle plots, which would show the moment at which the piece of steel was broken. This entire process was automated so that after loading the steel, one click of a button would run one test. Razorblades were primarily bent with the device until they would break, and for this reason, the measuring tool was called the 'blade break test.' The work consisted of designing a robust mechanical system coupling the three devices mentioned above in series. Code was written in Visual Basic that managed all the individual devices in the measuring tool, getting them to work together and linking them with a computer.; (cont.) A user interface was designed with engineers in mind...