Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007. / Includes bibliographical references (leaves 78-80). / Field studies have demonstrated that it is possible to evaluate the state of many shipboard systems by analyzing the power drawn by electromechanical actuators [1], [2], [3], [4], [5]. One device that can perform such an analysis is the non-intrusive load monitor (NILM). This thesis investigates the use of the NILM as a supervisory control system in the engineering plant of gas-turbine-powered vessel. Field tests demonstrate that the NILM can potentially reduce overall sensor count if used in a supervisory control system. To demonstrate the NILM's capabilities in supervisory control systems, experiments are being conducted at the U.S. Navy's Land-Based Engineering Site (LBES) in Philadelphia, Pennsylvania. Following a brief description of the LBES facility and the NILM itself, this thesis presents testing procedures and methodology with results obtained during the extensive field studies. This thesis also describes the on-going efforts to further demonstrate and develop the NILM's capabilities in supervisory control systems. / by Patrick Lawrence Bennett. / Nav.E.and S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references. / Direct analysis of biologically-relevant entities such as nucleic acids and proteins offers the potential to outperform conventional analysis techniques and diagnostic methods through enhancements in speed, accuracy, and sensitivity. Nanofluidic systems with critical dimensions comparable to the molecular scale open up new possibilities for direct observation, manipulation and analysis of biomolecules (single or ensemble), thus providing a novel basis for ultra-sensitive and high-resolution sensors and medical diagnostic systems. Inspired by this concept, we have developed a new class of nanofluidic filter devices and have implemented them as controllable molecular sieves for rapid analytical separation of various physiologically-relevant molecules such as dsDNA and proteins. In addition, we have conducted theoretical studies of molecular sieving process in the context of periodic free-energy landscapes created by the patterned nanofluidic filter arrays. The kinetic model constructed based upon the equilibrium partitioning theory and the Kramers rate theory properly describes the field-dependent sieving behavior, presenting notable progress beyond the existing equilibrium model in conventional gels. / (cont.) In this thesis, we have further developed a microfabricated anisotropic sieving structure consisting of a two-dimensional periodic nanofluidic filter array (anisotropic nanofilter array, ANA). The designed structural anisotropy in the ANA causes different-sized biomolecules to follow distinct migration trajectories, leading to efficient continuous-flow separation. Continuous-flow separation of dsDNA and proteins covering broad biological size scales were achieved within a few minutes, thus demonstrating the potential of the ANA as a generic molecular sieving structure for an integrated biomolecule sample preparation and analysis system. / by Jianping Fu. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 165-[166]). / We present a model and analysis of a production line that processes different part types on unreliable machines which operate according to a priority rule. The production line consists of machines separated by storage areas in which parts flow in a fixed sequence. A machine operates on the highest priority part whenever possible, and only operates on lower priority parts when unable to produce the higher priority parts. Part priorities are static and are a function only of part type. The purpose of this thesis is to present mathematical formulations and algorithms for estimating production rates and average inventory levels for each part type in a flexible production line. The qualitative behavior of the multiple-part-type line under different supply and demand scenarios is described. / by Young Jae Jang. / Ph.D.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007. / Includes bibliographical references. / The purpose of this project was to develop an idea for a product that would help the elderly in their daily lives. The specific people that the product would target were those senior citizens who are still self-sufficient but are feeling the early stages of old age. This was an important project because such a product would have the potential to be beneficial for the elderly as well as marketable and profitable. There were many stages involved in coming up with an idea for a product. First, market research needed to be conducted in order to determine information about the target group. The research helped determine the size of the target group along with their lifestyles and opinions. Research was also done to analyze products that are currently on the market. After analysis of all the information, an exercise machine for the elderly was developed as an idea for the product. This exercise machine would be one that allowed the users to do moves similar to Tai Chi exercises. This would help the elderly with their range of motion, flexibility, and lower body strength. The product developed has a lot of potential for further research and progress. / by Marcus R. Carson. / S.B.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000. / Includes bibliographical references (p. 95-97). / Platform-based product families have been an effective way for companies to offer increased variety into markets, while containing the resulting complexity of developing large numbers of products. A product platform is the set of resources - components, processes, technologies, and knowledge - that are shared across multiple products offered by a firm. The products derived from that common platform are called the variants, and the set of variants forms a product family. This thesis presents a theoretical basis for modeling the design of platform-based product families, as well as practical implementations based on those models. The problem is formulated as an optimization, where the requirements of the desired variants must be balanced against family objectives, such as maximizing the value of developing the family. A general case is formulated that covers the effects of using a platform-based design on the benefits and investments required to produce the desired family. The problem is then simplified into a two-step optimization approach to apply it to actual design situations for complex products. The first stage considers the technical details of creating feasible product families that satisfy the variants' requirements while optimizing the expected value to the firm. The second stage evaluates the design alternatives generated by the first step, considering the effects of uncertainty during the actual development of the family on its value to the firm. This evaluation is then used to select the most appropriate choice of family design. A case study of the design of multiple NASA exploratory space missions based on alternative telecommunications technology platforms is shown. Applying the approach resulted in several alternative family designs, some of which had not been previously considered viable. The resulting candidate designs were evaluated through the use of decision analysis models developed in this thesis, which calculate the value to the firm of each design. Simulation was then used to evaluate the value of each alternative and its flexibility to changes in uncertain factors during the development process. As a reference, a Pugh-type selection method (a qualitative, multi-criteria approach) was also explored and applied to the example of platform-based spacecraft design. / by Javier P. Gonzalez-Zugasti. / Ph.D.

Thesis: S.B. in Mechanical Engineering and Ocean Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references (page 15). / The vertical structure of swash-zone flows and turbulence, which is critical to sediment transport and flooding due to over-topping of dunes, will be examined using a Smoothed Particle Hydrodynamics model (DualSPHysics) evaluated with field observations obtained near La Jolla, CA in fall 2003. The mesh-free model is based on the Lagrangian description of fluid particle motion, and is capable of tracking free surfaces with discontinuities, moving boundaries, and large deformations; such as those in plunging waves and hydraulic jumps that occur when a swash backwash collides with the following uprush. The model is initialized with a flat sea surface and the measured beach profile and is forced at the offshore boundary with waves observed in 5 m water depth. The model is used to simulate the cross-shore and vertical structure of wave orbital motions, turbulence, and time-mean flows across the surf zone to the swash zone over 10 min periods. Model simulations are compared with field observations of waves and mean flows collected near the bed in 2.5, 1.5, and 1.0 m water depths and at 5 locations in the swash zone. Offshore significant waves heights ranged from 0.5 m to 1.5 m and cross-shore velocities in the surf and swash were up to 0.8 in/s. Model-data comparisons will be presented, the dependence of simulations on free parameters such as smoothing length, distance between particles, and artificial viscosity will be described, and the simulated flows and turbulence will be discussed. / by Mary Munro. / S.B. in Mechanical Engineering and Ocean Engineering

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 203-220). / Slug flow commonly occurs in gas and oil systems. Current predictive methods are based on mechanistic models, which require the use of closure relations to complement the conservation equations to predict integral flow parameters such as liquid holdup (or void fraction) and pressure gradient. These closure relations are typically developed either empirically or from semi-empirical models assuming idealized geometry of the interface, thus they carry the highest uncertainties in the mechanistic models. In this work, sensitivity analysis has determined that Taylor bubble velocity in slug flow is one such closure relation which significantly affects the calculation of these parameters. The main objective is to develop a unified higher-fidelity closure relation for Taylor bubble velocity. Here, we employ a novel approach to overcome the experimental limitations: validated 3D Computational Multiphase Fluid Dynamics (CMFD) with Interface Tracking Methods (ITMs) where the interface is tracked with a Level-Set method implemented in the commercial code TransAT®. In the literature, the Taylor bubble velocity is modeled based on two different contributions: (i) the drift velocity, i.e., the velocity of propagation of a Taylor bubble in stagnant liquid, and (ii) the liquid flow contribution. Here, we first analyze the dynamics of Taylor bubbles in stagnant liquid by generating a large numerical database that covers the most ample range of fluid properties and pipe inclination angles explored to date (Eo [epsilon] [10, 700], Mo [epsilon] [1 . 10-6, 5 . 103], and [theta] [epsilon] [0°, 90°]). A unified Taylor bubble velocity correlation, proposed for use as a slug flow closure relation in the mechanistic model, is derived from that database. The new correlation predicts the numerical database with 8.6% absolute average relative error and a coefficient of determination R² = 0.97, and other available experimental data with 13.0% absolute average relative error and R² = 0.84. By comparison, the second best correlation reports absolute average relative errors of 120% and 37%, and R² = 0.40 and 0.17, respectively. Furthermore, two key assumptions made in the CMFD simulations are justified with simulations and experiments: (i) the lubricating liquid film formed above the bubble as the pipe inclines with respect to the horizontal does not breakup, i.e., the gas phase never touches the pipe wall and triple line is not formed; and (ii) the Taylor bubble length does not affect its dynamics in inclined pipes. To verify the robustness of the first assumption, the gravity-induced film drainage is analytically modeled and experimentally validated. From this model, a criterion to avoid film breakup is obtained, which holds in the simulations performed. The second assumption is validated with both experiments and simulations. Finally, simulations of Taylor bubbles in upward and downward fluid flow in vertical and inclined pipes are performed, from where it is concluded that an improvement of the current velocity prediction models is needed. In particular, Taylor bubbles in vertical downward flow where the bubble becomes non-axisymmetric at high enough liquid flows are remarkably ill-predicted by current correlations. / by Enrique Lizarraga-Garcia. / Ph. D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997. / Includes bibliographical references (leaves 80-82). / by Sigit P. Santosa. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1984. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Roberto Barletta. / M.S.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004. / Includes bibliographical references (leaf 44). / The absorption of energy during impacts is ubiquitous in society. From our car seats to body armor, the ability to divert or dissipate unwanted energy is an aspect that has many engineering challenges. One approach to this issue is the use of fluid-filled elastomeric foams. In the present thesis, the fluid within these foams is a non-Newtonian shear-thickening fluid composed of 300 nm silica particles suspended in a solvent, ethylene glycol, at high concentrations, 45-55 %. The field of energy absorption using elastomeric foams has been extensively researched in industry. In addition, the effects and mechanism driving shear-thickening fluids (STF's) has also been well studied in industries involving particle suspensions, such as paints and medical applications. This research intends to combine the analysis of these two systems in an effort to characterize advanced energy absorption mechanism. It was found that the primary factors dominating fluid filled foams containing this STF are the volume fractions and compressional strain rate. In addition, the energy absorption capability of these foams has been compared to that of 'dry' foams and Newtonian-fluid filled foams, and has demonstrated an increase in energy absorption capabilities. / by Jose G. Ramirez. / S.B.