Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1987. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Bibliography: leaves 126-134. / by Carl P. Tausczik. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000. / Includes bibliographical references (p. 75). / As the use of distributed engineering models becomes more prevalent, engineers need tools to evaluate the quality of these models and understand how subsystem uncertainty affects predictions of system behavior. This thesis develops a tool that enables designers and engineers to specify their perceptions of confidence. These data are then translated into appropriate probability distributions. Monte-Carlo-based methods are used to automatically provide correct propagation of these distributions within an integrated modeling environment. A case study using an assembly tolerance problem is shown and different confidence modeling methods are compared. The methods benchmarked are: worst case; statistical; conventional Monte Carlo simulation; and the dynamic Monte Carlo tool developed in this thesis. Finally the dynamic Monte Carlo tool is used together with surrogate modeling techniques. Comparisons based on implementation time, model execution time, and robustness are provided. / by Jeffrey M. Lyons. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (p. 97-101). / To be implementable in safety critical applications, adaptive controllers must be shown to behave strictly according to predetermined specifications. This thesis presents two tools for verifying specifications relevant to practical direct-adaptive control systems. The first tool is derived from an asymptotic analysis of the error dynamics of a direct adaptive controller and uncertain linear plant. The analysis yields a so called Reduced Linear Asymptotic System, which can be used for designing adaptive systems to meet transient specifications. The tool is demonstrated in two design examples from flight mechanics, and verified in numerical simulation. The second tool developed is an algorithm for direct-adaptive control of plants with magnitude saturation constraints on multiple inputs. The algorithm is a non-trivial extension of an existing technique for single input systems with saturation. Boundeness of all signals is proved for initial conditions in a compact region. In addition, the notion of a class of multi-dimensional saturation functions is introduced. The saturation compensation technique is demonstrated in numerical simulation. Finally, these tools are applied to design a direct-adaptive controller for a realistic multi-input aircraft model to accomplish control reconfiguration in the case of unforeseen failure, damage, or disturbances. A novel control design for incorporating control allocation and reconfiguration is introduced. The adaptive system is shown in numerical simulation to have favorable transient qualities and to give a stable response with input saturation constraints. / by Mac Schwager. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007. / Includes bibliographical references (leaves 70-74). / Introduction: Effective local drug delivery to contractile tissues such as skeletal muscle requires a thorough understanding of the impact of mechanical loads on intramuscular pharmacokinetics. Current preparations for studying skeletal muscle biomechanics typically use: mounting techniques that lead to mechanical disruption of the tissue, which can create drug transport artifacts. In order to accurately study mechanical influences on drug transport, experimental techniques and setups need to meet the particular design requirements of both biomechanical testing setups and local drug delivery preparations. Studies of intramuscular pharmacokinetics require anatomically physiologic and functionally viable conditions for accurate drug transport. In this study, we invent a method for the surgical isolation and mounting of whole skeletal muscles of small rodents that maintains the physiologic configuration of the tissue. We also invent a mounting assembly and dynamic loading system designed appropriately for in vitro drug transport studies. We present an effective protocol for tissue processing and visually quantifying intramuscular distribution of drug. With the primary objective of investigating muscle pharmacokinetics, we use these techniques in a study to elucidate the influence of mechanical loading on the intramuscular transport and distribution of locally delivered drug. Methods and Results: The dynamic loading system was characterized and used to investigate intramuscular transport of aqueous macromolecular drug. The loading system was designed to achieve a maximal force, velocity, and acceleration of up to 72N, 0.45m/s, and 8.5m/s2, respectively, for imposing cyclic strain on soleus muscle samples. Total compliance of the series assembly from the motor to muscle mounting blocks was less then 0.0057 ± 0.002mm/N. / (cont.) Under proportional-integral-derivative (PID) control with a positional resolution of 20gpm, the loading system achieved a positional precision of +60gm or better for sinusoidal reference curves required in our studies. Tissue architectural and functional integrity as well as a technique for quantifying intramuscular fluorescent dextran were validated using the loading system. Histologic studies of rat soleus showed that interstitial porosity was consistent in tissues subjected to mechanical loading for 70 minutes, and changes in porosity were independent of the nature of imposed static (0-15% fixed strain) and cyclic (3Hz sinusoidal strain with amplitude of 2.5% oscillating about mean strains of 5-15%) loads. Permanent changes in architectural integrity depended only on the duration of time spent in vitro after isolation, in which porosity increased at the tissue edge from 11.1 + 3.3% to 21.0 + 6.1% over the course of a 70-minute incubation. The source solution used for local delivery of drug (dextran) preserved tissue functional viability, allowing muscle samples to maintain isometric twitch contractile activity at a rate of 3Hz for at least 1 hour. The active twitch force- length characteristic of soleus samples showed 0.24 + 0.06N at 0% strain, a maximum of 0.35 + 0.06N at 10% strain, and a decrease to 0.19 + 0.06N at 20% strain. Isometric twitch contractile force was at least 0.19N when measured every 15 minutes over a 2 hour period. Fractional volume of distribution for dextran was 84% of the bulk source concentration over the range of 0.1 M-lmM bulk concentrations, and demonstrated the non-binding properties of dextran. Fluorescence intensity of FITC-dextran equilibrated in soleus tissue exhibited a linear dependence on dextran concentration. / (cont.) Dextran penetration and distribution in soleus muscles under either cyclic (3Hz, 0-20% peak-to- peak) or static (fixed at 0%) tensile strain for 80 minutes was quantified by fluorescent imaging. Penetration depth of 1mM 20kDa FITC-dextran at the planar surfaces of the soleus increased significantly from 0.52 + 0.09mm under static strain to 0.81 + 0.09mm under cyclic strain. Penetration at the curved margins of the soleus was significantly greater than at planar surfaces by a factor of 1.57 and 2.52 under static and cyclic strain, respectively. Penetration at curved surfaces increased to a greater extent, by a factor of 1.6, than at planar surfaces under cyclic strain. Discussion: This investigation demonstrated that dynamic, or cyclic, tensile strain impacts the penetration and distribution of aqueous drug in skeletal muscle. In the course of this study, we established an effective and robust experimental system and protocol for studying mechanical influences on intramuscular pharmacokinetics. The innovation of our surgical isolation and mounting technique allowed for the investigation of an isolated soleus muscle without disrupting the muscle, tendons, or physiologic bone attachments. The mounting device enabled muscles to be secured in a physiologic in situ configuration, to undergo more physiologically distributed tensile stresses and strains, and to be mechanically loaded while incubated in vitro in drug. Thus, the method and device eliminated the artificial tissue stresses typically introduced by current tissue handling techniques that could result in drug transport artifacts. / (cont.) While effective as a standalone biomechanical testing preparation, characterization and validation of the dynamic loading system with a protocol for tissue processing and quantitative assessment of intramuscular fluorescent drug distribution demonstrated that it is a novel and robust preparation for investigating both tissue biomechanics and pharmacokinetics. With the finding from the present study that dynamic loading influences intramuscular drug transport in an architecturally dependent manner, we intend to investigate the isolated effects of different mechanical loading regimens on drug transport to establish a broader understanding of muscle pharmacokinetics. It is hoped that the insights from this work will guide the design and application of future local drug delivery strategies to mechanically active tissues. / by Peter I-Kung Wu. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997. / Includes bibliographical references (p. 93-94). / by Brian J. Bowers. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997. / Includes bibliographical references (p. 132-133). / by Bradley S. Homann. / M.S.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2009. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 20). / This experiment measured the level of sound emitted over the course of the print cycle by an HP inkjet printer and determined how the level varies with changes in the print quality settings and stages of the print cycle. As a test document was printed on the printer at various print quality settings and in two different environments-in a dorm room and in a laboratory chamber, a Sound Level Meter measured the sound intensity over the course of the entire print cycle and recorded the values. While sound levels were similar across some stages of the print job, in the actual printing step, the sound level varied directly with the quality and inversely with the time spent printing. For the normal quality setting, the mean sound level in the dorm room [in the chamber] was 55.242 ± 2.41 dB [56.911 ± 2.12 dB] with 12.4 s [12.4 s] of actual printing. These results have implications for a new generation of inkjet printers. Additionally, this experiment determined the noise contributors to a laboratory room containing an optical trap. The laser's fan-based cooling system yields frequencies of approximately 270 Hz and 540 Hz in the room, while the room's heater produces frequencies of approximately 110 Hz. The devices contributing to frequency peaks are the laser's fan-based cooling system and the room heaters. The fan-based cooling system produced consistent frequencies of approximately 270 Hz and 540 Hz. Also, the room heaters yield a lower frequency output of approximately 110 Hz. Even with all controllable devices turned off, a 33.5 Hz low frequency noise is present in the sound power spectrum FFT graph, most likely from the refrigerator outside the room of interest. To reduce the effect of the electronic equipment's frequencies on the high precision measurements acquired in the optical trap room, data should be taken with the two rooms' heaters off, and a quieter method of cooling the laser should be investigated. / by Jennifer H. Moore. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. Page 210 blank. / Includes bibliographical references (p. 195-197). / Cylindrical flexures (CFs) are defined as systems composed of flexural elements whose length is defined by the product of their radius of curvature, R, and sweep angle, [phi]. CFs may be constructed out of a cylindrical stock which leads to geometry, manufacturability, and compatibility advantages over planar flexures. However, CFs present a challenge because their mechanics differ from those of straight beams, and although the modeling of curved beams has been researched in detail [1-4], it has yet to be distilled into compliant element and system creation rules. The lack of relevant design rules has inhibited the process of concept generation and optimization of CF systems, preventing these systems from becoming pervasive in engineering applications. The design guidelines and models developed in this work enable (i) the rapid generation of multiple concepts, (ii) the efficient analysis of different designs and selection of the best design, and (iii) the effective optimization of the chosen concept. The CF synthesis approach presented in this thesis has three components: (i) analysis of element mechanics models to reveal key parameters, (ii) understanding of how the key parameters affect the flexure performance and (iii) guidelines as to how to assemble and optimize CF systems. With the knowledge generated designers will be able to rapidly layout possible designs using the element building blocks and system creation rules, and then use the identified key parameters to optimize a design. The synthesis guidelines were established and tested through the development of two case study flexures: a CF linear guide and an x-y-[theta]z stage. The case studies demonstrate the increased design space of CF systems, which makes it possible for these new flexure mechanisms to meet functional requirements that could not be met using traditional straight-beam flexures. / by Maria J. Telleria. / Ph.D.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000. / Includes bibliographical references (p. 47). / Double-skin airflow facades have been in use for several years in European countries. They have yet to be used in the United States. One factor is that there is a lack of a heat transfer model which can accurately predict facade performance. A model of performance has been developed by Daniel Arons. The goal of the work presented is to verify the model with experimentation on a small-scale facade. Sunlight was simulated with a 400 W metal halide High Intensity Discharge lamp. Outdoor summer conditions were simulated with a residential space heater. Two 1/8" thick panes of uncoated window glass, separated by 7", with 1" white aluminum blinds in the center, made up the facade structure. Air was driven through the channel at velocities up to 0.7 mis. The results of experimentation validate the model when no light is being projected on the facade. More work needs to be done to refine the model for cases where there is little or no airflow and also when light is shining on the facade. More specifically, the interaction between incident radiation and blinds should be refined. The greatest discrepancy between model and experiment occurs for the surface temperature of glass on the heated side. / by Jui-Chen Chang. / S.B.

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 53-55). / Removing necrotic tissue and foreign materials from wounds is a critical step in the management and treatment of chronic wounds. MIT's BioInstrumentation Laboratory developed a novel debridement technology that uses two high-speed impinging water jets to excise necrotic tissue. However, this device potentially causes accidental injection of water into healthy tissue beneath the wound bed, which can cause injury and necrosis in the healthy tissue. The purpose of this thesis is to explore tissue tension as a solution to reduce the required cutting power and consequently reduce water injection to acceptable levels. After validating the positive effect of tissue tension on the cutting efficiency of the water jet debridement device, we developed a technology that uses angled rolling wheels to tension tissue prior to debridement. This novel tensioner was qualitatively tested and successfully applied local tension at the site of cutting. Suggestions for further testing to improve this device are given. This tissue tensioner shows promise as a complementary appendage to the water jet debridement device. / by Colette P. Abah. / S.B.