MIT Librarieshttp://hdl.handle.net/1721.1/75812019-02-16T16:01:52Z2019-02-16T16:01:52ZConnections between circuit analysis problems and circuit lower boundsMurray, Cody (Cody Daniel)http://hdl.handle.net/1721.1/1204672019-02-16T07:18:42Z2018-01-01T00:00:00ZConnections between circuit analysis problems and circuit lower bounds
Murray, Cody (Cody Daniel)
A circuit analysis problem takes a Boolean function f as input (where f is represented either as a logical circuit, or as a truth table) and determines some interesting property of f. Examples of circuit analysis problems include Circuit Satisfiability, Circuit Composition, and the Minimum Size Circuit Problem (MCSP). A circuit lower bound presents an interesting function f and shows that no "easy" family of logical circuits can compute f correctly on all inputs, for some definition of "easy". Lower bounds are infamously hard to prove, but are of significant interest for understanding computation. In this thesis, we derive new connections between circuit analysis problems and circuit lower bounds, to prove new lower bounds for various well-studied circuit classes. We show how faster algorithms for Circuit Satisfiability can imply non-uniform lower bounds for functions in NP and related classes. We prove that MCSP cannot be NP-hard under "local" gadget reductions of the kind that appear in textbooks, and if MCSP proved to be NP-hard in the usual (polynomial-time reduction) sense then we would also prove longstanding lower bounds in other regimes. We also prove that natural versions of the Circuit Composition problem do not have small circuits that are constructible in very small (logarithmic) space.
Thesis: Ph. D. in Computer Science and Engineering, Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.; Cataloged from PDF version of thesis.; Includes bibliographical references (pages 107-112).
2018-01-01T00:00:00ZStopping self-discharge in metal-air batteriesHopkins, Brandon J. (Brandon James)http://hdl.handle.net/1721.1/1204662019-02-16T07:18:41Z2018-01-01T00:00:00ZStopping self-discharge in metal-air batteries
Hopkins, Brandon J. (Brandon James)
Metal-air batteries boast high theoretical energy densities, but negative electrode corrosion can severely reduce their usable capacity and commercial utility. Most methods to mitigate corrosion focus on electrode and electrolyte modification such as electrode alloying, electrolyte additives, and gel and nonaqueous electrolytes. These methods, however, either insufficiently suppress the parasitic reaction or compromise power and energy density. This thesis focuses on a different approach to corrosion mitigation involving electrolyte displacement from the electrode surface. Multiple electrolyte-displacement concepts were generated and investigated. The most promising of the concepts was the reversible displacement of the electrolyte from the electrode surface with an oil. To enable this method, the fundamental physics of underwater oil-fouling resistant surfaces was investigated, tested, and characterized. Design equations that aid in the appropriate selection of electrodes, displacing oils, and separator membranes were also developed. The oil displacement method was demonstrated in a primary (single-use) aluminum-air (Al-air) battery that achieved a 420% increase in useable energy density and was estimated to enable pack-level energy densities as high as 700 Wh 1- and 900 Wh kg-1. This method could, in principle, be used in any of the metal-air batteries, aqueous or nonaqueous, or in other energy storage systems that suffer from corrosion if appropriate displacing oils and separator membranes are found using the discussed design principles. With the oil displacement method, aqueous metal-air batteries that rely on abundant, broadly dispersed materials could provide safe, low-cost, sustainable primary and secondary (rechargeable) batteries for many applications including grid-storage, off-grid storage, robot power, and vehicular propulsion.
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.; Cataloged from PDF version of thesis.; Includes bibliographical references (pages 67-78).
2018-01-01T00:00:00ZDigital computer study of the effects of manufactured errors on dynamic gear loadsMeacher, Michael G. (Michael Garin)http://hdl.handle.net/1721.1/1204552019-02-15T07:21:14Z1960-01-01T00:00:00ZDigital computer study of the effects of manufactured errors on dynamic gear loads
Meacher, Michael G. (Michael Garin)
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1960.; Includes bibliographical references (leaf 67).
1960-01-01T00:00:00ZThe effects of thermal history and degree of cross-polymerization on the thermochromic behavior of diacetylene-containing polyestersStengel, Kellyhttp://hdl.handle.net/1721.1/1204542019-02-15T07:21:14Z1994-01-01T00:00:00ZThe effects of thermal history and degree of cross-polymerization on the thermochromic behavior of diacetylene-containing polyesters
Stengel, Kelly
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1994.; Includes bibliographical references (leaves 32-33).
1994-01-01T00:00:00Z