Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1990. / Includes bibliographical references (leaves 114-115). / by Marc C. Filerman. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (leaves 146-148). / The purpose of this research was to generate the knowledge required to design compliant mechanisms that (1) attenuate undesired small-motion angular vibrations in rotational power transmission systems and (2) preserve the desired transmission of large-motion torque/angle inputs. This thesis investigates the design of vibration attenuating compliant mechanisms that are directly integrated into the load path of rotational systems. These devices enable designers to attenuate the amplitude of undesirable vibrations while simultaneously optimizing the transmission of torque inputs. The design, modeling, fabrication and experimental validation of two Compliant Vibration Attenuator (CVA) concepts will be presented. The first device, the Small Amplitude Vibration Isolator (SAVI), is a non-linear compliant device that isolates a resonating or non-resonating rotational system from vibrations by acting as a mechanical lowpass filter. The second device, the Damping Vibration Link (DVL) utilizes compliance and damping to attenuate undesired vibrations due to resonance. A linear lumped parameter model was created in Matlab® to simulate the static and dynamic characteristics of rotational power transmission systems. This model enables one to determine the dynamic characteristics of a system for a given set of inputs, thereby making it possible to (1) understand the requirements for the CVA and (2) ascertain the effect of the CVA on the system. Finite-element simulations were conducted to verify an empirical, parametric model that describes the performance of a SAVI as a function of its stiffness parameters. / (cont.) Proof-of-concept prototypes were tested to verify performance predictions and to determine the practical issues related to implementation. The thesis concludes with a case study which demonstrates the effectiveness of a SAVI when integrated into the steering system of a light-duty pickup truck. The SAVI was shown to offer a 60% reduction in vibration amplitude by trading off 7 ms of delay in steering wheel-vehicle response. / by Spencer E. Szczesny. / S.M.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (leaves 36-37). / Hepatocyte morphology is known to be closely linked to cellular functions. As a result, morphogenesis is extremely important to attain organ-equivalent levels of tissue function from in vitro cultures. Thus, a challenge exists in designing materials suitable for supporting liver-derived cells that are not only biochemically hepatospecific but also biophysically sensitive to the mechanical nature of hepatocytes to achieve highly differentiated cell phenotype found in a natural liver. We employ a unique substrate material system of polyelectrolyte multilayers (PEM) that can be tuned to achieve mechanical compliances of several orders of magnitudes (Es = 105 to Es = 108 Pa). We have shown that PEM modification can effectively change the surface mechanical compliance, and, thus, hepatocyte morphology and attachment, by looking at varying PEM pH deposition conditions (pH 2.0, 4.0, and 6.5) and collagen concentrations (0, 3, 10 ug/cm ) on different materials (tissue-culture polystyrene, polycarbonate, and Permanox). For all materials, PAH/PAA 4.0/4.0 provided the balance of cellular attachment that appeared neither confluent nor sparse while also promoting a natural hepatocyte phenotype. / (cont.) We also observed that PEM films can effectively mask any inherent substrate material properties. Therefore, the use of PEM modification can be applied to a variety of surfaces and geometries for hepatocyte cultures. We believe that PEM is an invaluable tool in optimizing cellular attachment and function and will prove to be essential to future in vitro hepatocyte studies. / by Jonathan Wu. / S.B.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (leaves 51-54). / Endothelial dysfunction is a precursor to atherosclerosis. Thus, the vascular health of an individual can be assessed if endothelial dysfunction can be readily and unambiguously quantified. A thermal-based approach using temperature and blood perfusion measurements in conjunction with an arterial challenge has the potential to quantitatively assess endothelial dysfunction. This report includes a detailed review of previous attempts to characterize endothelial dysfunction and a preliminary evaluation of a thermal-based approach that relies on temperature and perfusion measurements. Two simple thermal models are used to contextualize results obtained from this technique. Results reveal that this thermal-based method serves as a valid indicator of endothelial assessment while at the same time reducing some of the mitigating factors of existing approaches to identifying endothelial dysfunction. More testing must be performed in order to optimize this thermal-based approach. / by Muyinatu A. Lediju. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995. / Includes bibliographical references (leaves 111-120). / by Leonid C. Lev. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000. / Includes bibliographical references (leaves 64-65). / by Winston Chi Hang Fan. / S.M.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014. / 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. / Includes bibliographical references. / Pharmaceutical manufacturing has traditionally been considered largely a matter of regulatory compliance. Consequently, it has been inefficient, but it is now increasingly being recognized as an opportunity for cost reduction. Recent initiatives by regulatory authorities, and by the industry, aim at easing regulations and encouraging process innovation. Even though significant improvements, especially in process control and minimization of process interruptions, have been achieved, the underlying process technology has not changed for decades. For example, typical process steps to produce the most common pharmaceutical products, immediate-release solid dosage forms, from drug substance and excipient are: blending, wet granulating, drying, milling and screening, blending, tableting, coating, and so on. A new process, such as blending combined with solvent-less, multi-component injection-molding could greatly simplify manufacturing. Injection-molding, however, yields a non-porous material, intrinsically different from the state-of-the-art powder-compacted, porous dosage forms. This may appear problematic, because current products rely on a large surface area-to-volume ratio to achieve immediate drug release. In addition, process rates previously achieved by injection-molding solid dosage forms have been comparably low -- offsetting some of the benefits offered by that process. In this thesis, an analytical approach is first developed to model drug release from non-porous dosage forms, comprising a fast eroding excipient and randomly distributed drug particles in it. The model considers the central role of microstructure in drug release. Particular importance is given to the role of clusters of connected, slowly eroding drug particles, and to the effect of drug particle protrusion, due to their slow erosion rate, from the eroding excipient surface. The model is validated by dissolution experiments. Good agreement is observed between the model and the experimental data. The drug release model is then used in product design for manufacturing as an optimization problem -- with manufacturing performance as objective function and design specifications as constraints. It is found that the drug volume fraction needs to be about 0.5 to efficiently produce non-porous dosage forms in specification, which implies that an excessive amount of excipient material is required. Therefore, new product designs are proposed: a cellular excipient micro-structure with up to ten-fold reduction in excipient content. The new designs are further shown to allow injection-molding of immediate-release dosage forms that meet specifications with a three-fold increase in injection-molding process rate compared with conventional designs. / by Aron H. Blaesi. / Ph. D.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1991. / Includes bibliographical references (leaf 46). / by Stephen Thomassy Root. / B.S.

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017. / DISCLAIMER NOTICE: The pagination in this thesis reflects how it was delivered to the Institute Archives and Special Collections, Massachusetts Institute of Technology. Cataloged from PDF version of thesis. / Includes bibliographical references (page 24). / The Kendall Band is an interactive musical sculpture by Paul Matisse located within the MBTA's Kendall/MIT Train Station. The sculpture, installed in 1987, consists of three instruments, Kepler, Galileo, and two sets of bells known as Pythagoras, each operated by its own system of mechanisms and linkages, and "played" by passengers using handles located on each platform. The sculpture as a whole has ceased to function as a result of a series of mechanical failures. Repair needs outpaced the resources available to maintain the sculpture. The primary known failure points are located within the portion of the actuation system on the platform of the station. Several components within this current actuation system are prone to fracture and wear. A new actuation system has been designed with various features that serve to increase overall durability, including a kinematic coupling with a spring-loaded interface that decouples actuation above a torque threshold of 225 in-lbf. Additionally, the newly designed actuation system has been standardized across all three instruments to simplify maintenance of the sculpture by incorporating a modular plate that has connection points for each instrument. Preliminary load testing performed upon a simplified version of the coupling interface proved promising for the design, but further work is required to prepare the design for installation. / by Marian Heman-Ackah. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1992. / Includes bibliographical references. / by Xin Liu. / Ph.D.