New algorithm for efficient prediction of Casimir interactions among arbitrary materials in arbitrary geometries

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 161-163).For most of its 60 year history, the Casimir effect was an obscure theoretical backwater, but technological advances over the past decade have promoted this curious manifestation of quantum and thermal fluctuations to a position of central importance in modern experimental physics. Dramatic progress in the measurement of Casimir forces since 1997 has created a demand for theoretical tools that can predict Casimir interactions in realistic experimental geometries and in materials with realistic frequency-dependent electrical properties. This work presents a new paradigm for efficient numerical computation of Casimir interactions. Our new technique, which we term the fluctuating-surface-current (FSC) approach to computational Casimir physics, borrows ideas from the boundary-element method of computational electromagnetism to express Casimir energies, forces, and torques between bodies of arbitrary shapes and materials in terms of interactions among effective electric and magnetic surface currents flowing on the surfaces of the objects. We demonstrate that the master equations of the FSC approach arise as logical consequences of either of two seemingly disparate Casimir paradigms-the stress-tensor approach and the path-integral (or scattering) approach-and this work thus achieves an unexpected unification of these two otherwise quite distinct theoretical frameworks. But a theoretical technique is only as relevant as its practical implementations are useful, and for this reason we present three distinct numerical implementations of the FSC formulae, each of which poses a series of unique technical challenges. Finally, using our new theoretical paradigm and our practical implementations of it, we obtain new predictions of Casimir interactions in a number of experimentally relevant geometric and material configurations that would be difficult or impossible to treat with any other existing Casimir method.by M. T. Homer Reid.Ph.D

Computational inverse design of non-intuitive illumination patterns to maximize optical force or torque

This paper aims to maximize optical force or torque on arbitrary micro- and nanoscale objects using numerically optimized structured illumination. By developing a numerical framework for computer-automated design of 3d vector-field illumination, we demonstrate a 20-fold enhancement in optical torque per intensity over circularly polarized plane wave on a model plasmonic particle. The nonconvex optimization is efficiently performed by combining a compact cylindrical Bessel basis representation with a fast boundary element method and a standard derivative-free, local optimization algorithm. We analyze the optimization results for 2000 random initial configurations, discuss the tradeoff between robustness and enhancement, and compare the different effects of multipolar plasmon resonances on enhancing force or torque. All results are obtained using open-source computational software available online

Dual-Cation Electrolytes for High-Power and High-Energy LTO//AC Hybrid Capacitors

Dual-cation electrolyte systems, which contain two cations [Li+ and spiro-1,1′-bipyrrolidinium (SBP+), are proposed to enhance the power capability of hybrid capacitors composed of thick Li4Ti5O12 (LTO) negative (200 μm) and activated carbon (AC) positive electrodes (400 μm), which thus reduces the resistive overvoltage in the system. Detailed studies of the mass transport properties based on the combination of spectroscopy and electrochemical analysis have shown that the presence of SBP+, despite slower Li+ transport in the electrolyte bulk, further reduces overvoltage associated with migration limitation in the thick LTO electrode macropores. This study on the dual-cation electrolyte quantifies the influence of the addition of a supporting electrolyte and shows interest in SBPBF4 addition for increasing the output power density of hybrid capacitors with a thick electrode configuration

The origin of stability and high Co 2+/3+ redox utilization for FePO 4 -coated LiCo 0.90 Ti 0.05 PO 4 /MWCNT nanocomposites for 5 V class lithium ion batteries

The Fe 3+ -rich surface on LiCoPO 4 prevents from irreversible crystal structure change and electrolyte decomposition, leading to long term cyclability, while Ti 4+ -substitution contributes to the higher utilization of Co in LiCo 0.9 Ti 0.05 PO 4 crystals

The origin of stability and high Co 2+/3+ redox utilization for FePO 4 -coated LiCo 0.90 Ti 0.05 PO 4 /MWCNT nanocomposites for 5 V class lithium ion batteries

The Fe 3+ -rich surface on LiCoPO 4 prevents from irreversible crystal structure change and electrolyte decomposition, leading to long term cyclability, while Ti 4+ -substitution contributes to the higher utilization of Co in LiCo 0.9 Ti 0.05 PO 4 crystals

Electroweak parameters of the z0 resonance and the standard model

Contains fulltext : 124399.pdf (publisher's version ) (Open Access

Measurement of the Mass of the Z-Boson and the Energy Calibration of Lep

Contains fulltext : 26847___.PDF (publisher's version ) (Open Access

Electroweak parameters of the Z0^0 resonance and the standard model

Media temporalities of the elderly : evolutions in stability This article shows the context of analysis and the first results of a research on media temporalities of the elderly. Several works have finely analysed the diversity of the media practices and studied meanings of media uses. I wish to continue these analyses by insisting on the evolutionary and dynamic aspect of the practices and temporalities of users having expanded, enhanced, so called "interactive" radio and especially television programming. A priori, the elderly, upon retirement, have a "full-time free time". Their media practices seem strongly influenced by their first experiments ; the appropriation of the various peripheral accessories which gradually came with the media, to the latest digital ones, seems to reinforce their habits of watching television. Their representations and relations with times and media are very far away from the image of television like omnipresent media or "devourer of time". Rather, their media practices are to be understood like a temporality of the occupation, according to the expression of Gerard Derèze, characterized by interest and utility. A particular glance at the users who do not carry out a systematic selection of the programs, accepting the unforeseen, highlights an approach of media and time that allow "useful encounter" which I would qualify in a first stage by : "chance and encounter" and "random and the following". The few points presented here make me assume that the global relation of the autonomous elderly persons to the media can evolve when confronted to their new temporal framework and the new program offer, whereas their representations and use of the media remain quite stable

Electroweak parameters of the Z0^0 resonance and the standard model

Media temporalities of the elderly : evolutions in stability This article shows the context of analysis and the first results of a research on media temporalities of the elderly. Several works have finely analysed the diversity of the media practices and studied meanings of media uses. I wish to continue these analyses by insisting on the evolutionary and dynamic aspect of the practices and temporalities of users having expanded, enhanced, so called "interactive" radio and especially television programming. A priori, the elderly, upon retirement, have a "full-time free time". Their media practices seem strongly influenced by their first experiments ; the appropriation of the various peripheral accessories which gradually came with the media, to the latest digital ones, seems to reinforce their habits of watching television. Their representations and relations with times and media are very far away from the image of television like omnipresent media or "devourer of time". Rather, their media practices are to be understood like a temporality of the occupation, according to the expression of Gerard Derèze, characterized by interest and utility. A particular glance at the users who do not carry out a systematic selection of the programs, accepting the unforeseen, highlights an approach of media and time that allow "useful encounter" which I would qualify in a first stage by : "chance and encounter" and "random and the following". The few points presented here make me assume that the global relation of the autonomous elderly persons to the media can evolve when confronted to their new temporal framework and the new program offer, whereas their representations and use of the media remain quite stable

Search for the standard model Higgs boson at LEP

The four LEP Collaborations, ALEPH, DELPHI, L3 and OPAL, have collected a total of 2461 pb(-1) of e(+)e(-) collision data at centre-of-mass energies between 189 and 209 GeV. The data are used to search for the Standard Model Higgs boson. The search results of the four Collaborations are combined and examined in a likelihood test for their consistency with two hypotheses: the background hypothesis and the signal plus background hypothesis. The corresponding confidences have been computed as functions of the hypothetical Higgs boson mass. A lower bound of 114.4 GeV/c(2) is established, at the 95% confidence level, on the mass of the Standard Model Higgs boson. The LEP data are also used to set upper bounds on the HZZ coupling for various assumptions concerning the decay of the Higgs boson. (C) 2003 Elsevier B.V. All rights reserved