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Articles 1 - 30 of 83
Full-Text Articles in Physical Sciences and Mathematics
Analysis Of Salvinorin A In Plants, Water, And Urine Using Solid-Phase Microextraction-Comprehensive Two-Dimensional Gas Chromatography–Time Of Flight Mass Spectrometry, Brian Barnes, Nicholas Snow
Analysis Of Salvinorin A In Plants, Water, And Urine Using Solid-Phase Microextraction-Comprehensive Two-Dimensional Gas Chromatography–Time Of Flight Mass Spectrometry, Brian Barnes, Nicholas Snow
Nicholas A Snow
No abstract provided.
Effects Of Electrostatic Correlations On Electrokinetic Phenomena, Brian Storey, Martin Bazant
Effects Of Electrostatic Correlations On Electrokinetic Phenomena, Brian Storey, Martin Bazant
Brian Storey
The classical theory of electrokinetic phenomena is based on the mean-field approximation that the electric field acting on an individual ion is self-consistently determined by the local mean charge density. This paper considers situations, such as concentrated electrolytes, multivalent electrolytes, or solvent-free ionic liquids, where the mean-field approximation breaks down. A fourth-order modified Poisson equation is developed that captures the essential features in a simple continuum framework. The model is derived as a gradient approximation for nonlocal electrostatics of interacting effective charges, where the permittivity becomes a differential operator, scaled by a correlation length. The theory is able to capture …
Editorial: Social Implications Of Technology- “Il Buono, Il Brutto, Il Cattivo”, Katina Michael
Editorial: Social Implications Of Technology- “Il Buono, Il Brutto, Il Cattivo”, Katina Michael
Professor Katina Michael
Late last year, IEEE SSIT was invited to put together a paper for the centennial edition of Proceedings of the IEEE that was published in May 2012. The paper titled, “Social Implications of Technology: The Past, the Present, and the Future,” brought together five members of SSIT with varying backgrounds, and two intense months of collaboration and exchange of ideas. I personally felt privileged to be working with Karl D. Stephan, Emily Anesta, Laura Jacobs and M.G. Michael on this project.
Workshop Addresses Aviation Community, Jennifer Meehan, Joseph Kunches
Workshop Addresses Aviation Community, Jennifer Meehan, Joseph Kunches
Jennifer (Jinni) Meehan
No abstract provided.
The Minimum Span Of L(2,1)-Labelings Of Certain Generalized Petersen Graphs, Sarah Adams, Jonathan Cass, Matthew Tesch, Denise Troxell, Cody Wheeland
The Minimum Span Of L(2,1)-Labelings Of Certain Generalized Petersen Graphs, Sarah Adams, Jonathan Cass, Matthew Tesch, Denise Troxell, Cody Wheeland
Sarah Spence Adams
In the classical channel assignment problem, transmitters that are sufficiently close together are assigned transmission frequencies that differ by prescribed amounts, with the goal of minimizing the span of frequencies required. This problem can be modeled through the use of an L(2,1)-labeling, which is a function f from the vertex set of a graph G to the non-negative integers such that |f(x)–f(y)|≥ 2 if xand y are adjacent vertices and |f(x)–f(y)|≥1 if xand y are at distance two. The goal is to …
On An Orthogonal Space-Time-Polarization Block Code, Beata Wysocki, Tadeusz Wysocki, Sarah Adams
On An Orthogonal Space-Time-Polarization Block Code, Beata Wysocki, Tadeusz Wysocki, Sarah Adams
Sarah Spence Adams
Over the past several years, diversity methods such as space, time, and polarization diversity have been successfully implemented in wireless communications systems. Orthogonal space-time block codes efficiently combine space and time diversity, and they have been studied in detail. Polarization diversity has also been studied, however it is usually considered in a simple concatenation with other coding methods. In this paper, an efficient method for incorporating polarization diversity with space and time diversity is studied. The simple yet highly efficient technique is based on extending orthogonal space-time block codes into the quaternion domain and utilizing a description of the dual-polarized …
Novel Constructions Of Improved Square Complex Orthogonal Designs For Eight Transmit Antennas, Le Chung Tran, Tadeusz Wysocki, Jennifer Seberry, Alfred Mertins, Sarah Adams
Novel Constructions Of Improved Square Complex Orthogonal Designs For Eight Transmit Antennas, Le Chung Tran, Tadeusz Wysocki, Jennifer Seberry, Alfred Mertins, Sarah Adams
Sarah Spence Adams
Constructions of square, maximum rate complex orthogonal space-time block codes (CO STBCs) are well known, however codes constructed via the known methods include numerous zeros, which impede their practical implementation. By modifying the Williamson and Wallis-Whiteman arrays to apply to complex matrices, we propose two methods of construction of square, order-4n CO STBCs from square, order-n codes which satisfy certain properties. Applying the proposed methods, we construct square, maximum rate, order-8 CO STBCs with no zeros, such that the transmitted symbols are equally dispersed through transmit antennas. Those codes, referred to as the improved square CO STBCs, have the advantages …
Multilevel And Multidimensional Hadamard Matrices, Sarah Adams, Matthew Crawford, Caitlin Greeley, Bryce Lee, Mathav Murugan
Multilevel And Multidimensional Hadamard Matrices, Sarah Adams, Matthew Crawford, Caitlin Greeley, Bryce Lee, Mathav Murugan
Sarah Spence Adams
Multilevel Hadamard matrices (MHMs), whose entries are integers as opposed to the traditional restriction to {±1}, were introduced by Trinh, Fan, and Gabidulin in 2006 as a way to construct multilevel zero-correlation zone sequences, which have been studied for use in approximately synchronized code division multiple access systems. We answer the open question concerning the maximum number of distinct elements permissible in an order n MHM by proving the existence of an order n MHM with n elements of distinct absolute value for all n. We also define multidimensional MHMs and prove an analogous existence result.
An Extension Of The Channel-Assignment Problem: L(2, 1)-Labelings Of Generalized Petersen Graphs, Sarah Adams, Jonathan Cass, Denise Troxell
An Extension Of The Channel-Assignment Problem: L(2, 1)-Labelings Of Generalized Petersen Graphs, Sarah Adams, Jonathan Cass, Denise Troxell
Sarah Spence Adams
The channel-assignment problem involves assigning frequencies represented by nonnegative integers to radio transmitters such that transmitters in close proximity receive frequencies that are sufficiently far apart to avoid interference. In one of its variations, the problem is commonly quantified as follows: transmitters separated bythe smallest unit distance must be assigned frequencies that are at least two apart and transmitters separated by twice the smallest unit distance must be assigned frequencies that are at least one apart. Naturally, thischannel-assignment problem can be modeled with vertex labelings of graphs. An L(2, 1)-labeling of a graph G is a function f from the …
Identifying High-Dimension Subspace Subcodes Of Reed-Solomon Codes, Sarah Adams
Identifying High-Dimension Subspace Subcodes Of Reed-Solomon Codes, Sarah Adams
Sarah Spence Adams
Subspace subcodes of Reed-Solomon (SSRS) codes were introduced by Hattori, McEliece, Solomo, and Lin in the mid-1990s. These authors found a complicated dimension formula and a simple, tight lower bound on thedimension of SSRS codes over F2m. We prove a conjecture of Hattori concerning how to identify subspaces that can be used to build SSRS codes whose dimension exceeds this lower bound.
Quaternion Orthogonal Designs From Complex Companion Designs, Sarah Adams, Jennifer Seberry, Nathaniel Karst, Jonathan Pollack, Tadeusz Wysocki
Quaternion Orthogonal Designs From Complex Companion Designs, Sarah Adams, Jennifer Seberry, Nathaniel Karst, Jonathan Pollack, Tadeusz Wysocki
Sarah Spence Adams
The success of applying generalized complex orthogonal designs as space–time block codes recently motivated the definition of quaternion orthogonal designs as potential building blocks for space–time-polarization block codes. This paper offers techniques for constructing quaternion orthogonal designs via combinations of specially chosen complex orthogonal designs. One technique is used to build quaternion orthogonal designs on complex variables for any even number of columns. A second related technique is applied to maximum rate complex orthogonal designs to generate an infinite family of quaternion orthogonal designs on complex variables such that the resulting designs have no zero entries. This second technique is …
The Final Case Of The Decoding Delay Problem For Maximum Rate Complex Orthogonal Designs, Sarah Adams, Nathaniel Karst, Mathav Murugan
The Final Case Of The Decoding Delay Problem For Maximum Rate Complex Orthogonal Designs, Sarah Adams, Nathaniel Karst, Mathav Murugan
Sarah Spence Adams
Complex orthogonal space-time block codes (COSTBCs) based on generalized complex orthogonal designs (CODs) have been successfully implemented in wireless systems with multiple transmit antennas and single or multiple receive antennas. It has been shown that for a maximum rate COD with 2m-1 or 2m columns, a lower bound on decoding delay is (m-1 2m) and this delay is achievable when the number of columns is congruent to 0, 1 , or 3 modulo 4. In this paper, the final case is addressed, and it is shown that when the number of columns is congruent to 2 modulo 4, the lower …
On The Hole Index Of L(2,1)-Labelings Of R-Regular Graphs, Sarah Adams, Matthew Tesch, Denise Troxell, Bradford Westgate, Cody Wheeland
On The Hole Index Of L(2,1)-Labelings Of R-Regular Graphs, Sarah Adams, Matthew Tesch, Denise Troxell, Bradford Westgate, Cody Wheeland
Sarah Spence Adams
An L(2,1)-labeling of a graph G is an assignment of nonnegative integers to the vertices of G so that adjacent vertices get labels at least distance two apart and vertices at distance two get distinct labels. A hole is an unused integer within the range of integers used by the labeling. The lambda number of a graphG, denoted λ(G), is the minimum span taken over all L(2,1)-labelings of G. The hole index of a graph G, denoted ρ(G), is the minimum number of holes taken over all L(2,1)-labelings with span exactly λ(G). Georges and Mauro [On the structure of graphs …
The Minimum Decoding Delay Of Maximum Rate Complex Orthogonal Space–Time Block Codes, Sarah Adams, Nathaniel Karst, Jonathan Pollack
The Minimum Decoding Delay Of Maximum Rate Complex Orthogonal Space–Time Block Codes, Sarah Adams, Nathaniel Karst, Jonathan Pollack
Sarah Spence Adams
The growing demand for efficient wireless transmissions over fading channels motivated the development ofspace-time block codes. Space-time block codes built from generalized complex orthogonal designs are particularly attractive because the orthogonality permits a simple decoupled maximum-likelihood decodingalgorithm while achieving full transmit diversity. The two main research problems for these complex orthogonalspace-time block codes (COSTBCs) have been to determine for any number of antennas the maximum rate andthe minimum decoding delay for a maximum rate code. The maximum rate for COSTBCs was determined by Liang in 2003. This paper addresses the second fundamental problem by providing a tight lower bound on …
Trajectory Generation In High-Speed, High-Precision Micromilling Using Subdivision Surfaces, Athulan Vijayaraghavan, Angela Sodemann, Aaron Hoover, J. Mayor, David Dornfeld
Trajectory Generation In High-Speed, High-Precision Micromilling Using Subdivision Surfaces, Athulan Vijayaraghavan, Angela Sodemann, Aaron Hoover, J. Mayor, David Dornfeld
Aaron M. Hoover
Motion control in high-speed micromilling processes requires fast, accurate following of a specified curvilinear path. The accuracy with which the path can be followed is determined by the speed at which individual trajectories can be generated and sent to the control system. The time required to generate the trajectory is dependent on the representations used for the curvilinear trajectory path. In this study, we introduce the use of subdivision curves as a method for generating high-speed micromilling trajectories. Subdivision curves are discretized curves which are specified as a series of recursive refinements of a coarse mesh. By applying these recursive …
The Second Annual Space Weather Community Operations Workshop: Advancing Operations Into The Next Decade, Jennifer Meehan, Jared Fulgham, Kent Tobiska
The Second Annual Space Weather Community Operations Workshop: Advancing Operations Into The Next Decade, Jennifer Meehan, Jared Fulgham, Kent Tobiska
Jennifer (Jinni) Meehan
No abstract provided.
Synthesis Of Static And Dynamic Multiple-Input Translinear Element Networks, Bradley Minch
Synthesis Of Static And Dynamic Multiple-Input Translinear Element Networks, Bradley Minch
Bradley Minch
In this paper, we discuss the process of synthesizing static and dynamic multiple-input translinear element (MITE) networks systematically from high-level descriptions given in the time domain, in terms of static polynomial constraints and algebraic differential equations. We provide several examples, illustrating the process for both static and dynamic system constraints. Although our examples will all involve MITE networks, the early steps of the synthesis process are equally applicable to the synthesis of static and dynamic translinear-loop circuits.
Incommensurate Spin Fluctuations In High-Transition Temperature Superconductors, Barrett Wells, Young Lee, Marc Kastner, Rebecca Christianson, Robert Birgeneau, Kazuyoshi Yamada, Yasuo Endoh, Gen Shirane
Incommensurate Spin Fluctuations In High-Transition Temperature Superconductors, Barrett Wells, Young Lee, Marc Kastner, Rebecca Christianson, Robert Birgeneau, Kazuyoshi Yamada, Yasuo Endoh, Gen Shirane
Rebecca J. Christianson
Neutron scattering experiments have revealed a fascinating interplay between the hole doping, the spin fluctuations, and the superconductivity of the cuprate superconductors. Recently, electrochemical techniques have been used to produce large single crystals of La2CuO4+ y, which has mobile oxygen dopants. Staging behavior of the excess oxygen has been demonstrated, and the low-energy spin fluctuations in stage 6 La2CuO4+ y have been measured. The spin fluctuations are incommensurate with the lattice and have spatial, energy, and temperature dependencies very much like those in La2− xSrxCuO4, with similar high transition temperature. This establishes the universality of the incommensurate spin fluctuations among …
Structures And Incommensurate Spin Excitations In Excess Oxygen-Doped La2cuo4+Y, Robert Birgeneau, Rebecca Christianson, Yasuo Endoh, Marc Kastner, Young Lee, Gen Shirane, Barrett Wells, Kazuyoshi Yamada
Structures And Incommensurate Spin Excitations In Excess Oxygen-Doped La2cuo4+Y, Robert Birgeneau, Rebecca Christianson, Yasuo Endoh, Marc Kastner, Young Lee, Gen Shirane, Barrett Wells, Kazuyoshi Yamada
Rebecca J. Christianson
Over the past decade, we have studied in detail the low-energy spin fluctuations in :a2−xSrxCuO4 for xbetween 0 and 0.18. Our experiments, as well as those by others, have revealed a fascinating interplay between the hole doping, the static and dynamic spin fluctuations and superconductivity. Recently, using electrochemical techniques, we have learned how to produce large single crystals of La2CuO4+y which are relatively homogenous. In this latter system, the dopants are characterized by annealed rather than quenched disorder. Furthermore, we have demonstrated staging behavior of the excess oxygen analogous to staging in intercalated graphite. We have now succeeded in carrying …
A Reduced Model Of Cavitation Physics For Use In Sonochemistry, Brian Storey, Andrew Szeri
A Reduced Model Of Cavitation Physics For Use In Sonochemistry, Brian Storey, Andrew Szeri
Brian Storey
Sonochemistry involves focusing acoustic energy through cavitation bubbles to increase chemical activity. The violent bubble collapses lead to temperatures of several thousand kelvin, which drive chemical reactions. In previous work, we gave a detailed computational model of a single bubble collapse, taking into account phase change, mass diffusion, heat diffusion and chemical reactions. All of these phenomena are important in determining the conditions at collapse. The present work involves development of a much simpler model that includes all the physics relevant to the determination of the reaction products. Comparisons with the more detailed computations are made; the reduced model is …
Water Vapour, Sonoluminescence And Sonochemistry, Brian Storey, Andrew Szeri
Water Vapour, Sonoluminescence And Sonochemistry, Brian Storey, Andrew Szeri
Brian Storey
Sonoluminescence is the production of light from acoustically forced bubbles; sonochemistry is a related chemical processing technique. The two phenomena share a sensitive dependence on the liquid phase. The present work is an investigation of the fate and consequences of water vapour in the interior of strongly forced argon micro–bubbles. Due to the extreme nonlinearity of the volume oscillations, excess water vapour is trapped in the bubble during a rapid inertial collapse. Water vapour is prevented from exiting by relatively slow diffusion and non–equilibrium condensation at the bubble wall. By reducing the compression heating of the mixture and through primarily …
Temperature Distribution In An Oscillatory Flow With A Sinusoidal Wall Temperature, Eduardo Ramos, Brian Storey, Fernando Sierra, Raul Zuniga, Andriy Avramenko
Temperature Distribution In An Oscillatory Flow With A Sinusoidal Wall Temperature, Eduardo Ramos, Brian Storey, Fernando Sierra, Raul Zuniga, Andriy Avramenko
Brian Storey
The temperature field generated by an oscillatory boundary layer flow in the presence of a wall with a sinusoidal temperature distribution is analyzed. A linear perturbation method is used to find closed form analytical solutions for the temperature field when the amplitude of the velocity oscillation is small. The analytical solutions only consider long-time behavior when the temperature fields oscillate with the frequency of the flow. The structure of the equation that governs the temperature correction due to convection is similar to that of diffusive waves with the solution consisting of traveling or standing waves. The temperature distribution is also …
Double Layer In Ionic Liquids: Overscreening Versus Crowding, Martin Z. Bazant, Brian D. Storey, Alexei A. Kornyshev
Double Layer In Ionic Liquids: Overscreening Versus Crowding, Martin Z. Bazant, Brian D. Storey, Alexei A. Kornyshev
Brian Storey
We develop a simple Landau-Ginzburg-type continuum theory of solvent-free ionic liquids and use it to predict the structure of the electrical double layer. The model captures overscreening from short-range correlations, dominant at small voltages, and steric constraints of finite ion sizes, which prevail at large voltages. Increasing the voltage gradually suppresses overscreening in favor of the crowding of counterions in a condensed inner layer near the electrode. This prediction, the ion profiles, and the capacitance-voltage dependence are consistent with recent computer simulations and experiments on room-temperature ionic liquids, using a correlation length of order the ion size.
Mixture Segregation Within Sonoluminescence Bubbles, Brian D. Storey, Andrew J. Szeri
Mixture Segregation Within Sonoluminescence Bubbles, Brian D. Storey, Andrew J. Szeri
Brian Storey
This paper concerns a relaxation of the assumption of uniform mixture composition in the interior of sonoluminescence bubbles. Intense temperature and pressure gradients within the bubble drive relative mass diffusion which overwhelms diffusion driven by concentration gradients. This thermal and pressure diffusion results in a robust compositional inhomogeneity in the bubble which lasts several orders of magnitude longer than the temperature peak or light pulse at the main collapse of the bubble. This effect has important consequences for control of sonoluminescence, gas dynamics, sonochemistry, and the physics of light production.
Nonextensive Statistical Mechanics For Rotating Quasi-Two-Dimensional Turbulence, Sunghwan Jung, Brian Storey, Julien Aubert, Harry Swinney
Nonextensive Statistical Mechanics For Rotating Quasi-Two-Dimensional Turbulence, Sunghwan Jung, Brian Storey, Julien Aubert, Harry Swinney
Brian Storey
We have conducted experiments on an asymmetrically forced quasi-two-dimensional turbulent flow in a rapidly rotating annulus. Assuming conservation of potential enstrophy and energy, we maximize a nonextensive entropy function to obtain the azimuthally averaged vorticity as a function of radial position. The predicted vorticity profile is in good accord with the observations. A nonextensive formalism is appropriate because long-range correlations between small-scale vortices give rise to large coherent structures in the turbulence. We also derive probability distribution functions for the vorticity from both extensive and nonextensive entropies, and we find that the prediction from nonextensive theory is in better accord …
A Parameterized Stereo Vision Core For Fpgas, Mark Chang, Stephen Longfield
A Parameterized Stereo Vision Core For Fpgas, Mark Chang, Stephen Longfield
Mark L. Chang
We present a parameterized stereo vision core suitable for a wide range of FPGA targets and stereo vision applications. By enabling easy tuning of algorithm parameters, our system allows for rapid exploration of the design space and simpler implementation of high-performance stereo vision systems. This implementation utilizes the census transform algorithm to calculate depth information from a pair of images delivered from a simulated stereo camera pair. This work advances our previous work through implementation improvements, a stereo camera pair simulation framework, and a scalable stereo vision core.
Work In Progress - Synthesizing Design, Engineering, And Entrepreneurship Through A Mobile Application Development Course, Mark L. Chang
Work In Progress - Synthesizing Design, Engineering, And Entrepreneurship Through A Mobile Application Development Course, Mark L. Chang
Mark L. Chang
In this paper, we describe our experiences in designing and delivering a course that blends together design, engineering, and entrepreneurship through the use of mobile devices. The significance of this work is in advocating for and demonstrating the motivational and educational benefits of using a mobile platform, and describing how to utilize the mobile marketplace to provide an authentic, real-world experience across these three domains.
Precis: A Design-Time Precision Analysis Tool, Mark L. Chang, Scott Hauck
Precis: A Design-Time Precision Analysis Tool, Mark L. Chang, Scott Hauck
Mark L. Chang
Currently, few tools exist to aid the FPGA developer in translating an algorithm designed for a general-purpose-processor into one that is precision-optimized for FPGAs. This task requires extensive knowledge of both the algorithm and the target hardware. We present a design-time tool, Precis, which assists the developer in analyzing the precision requirements of algorithms specified in MATLAB. Through the combined use of simulation, user input, and program analysis, we demonstrate a methodology for precision analysis that can aid the developer in focusing their manual precision optimization efforts.
Precis: A Usercentric Word-Length Optimization Tool, Mark Chang, Scott Hauck
Precis: A Usercentric Word-Length Optimization Tool, Mark Chang, Scott Hauck
Mark L. Chang
Translating an algorithm designed for a general-purpose processor into an algorithm optimized for custom logic requires extensive knowledge of the algorithm and the target hardware. Precis lets designers analyze the precision requirements of algorithms specified in Matlab. The design time tool combines simulation, user input, and program analysis to help designers focus their manual precision optimization efforts.
Low-Cost Stereo Vision On An Fpga, Chris A. Murphy, Daniel Lindquist, Ann Marie Rynning, Thomas Cecil, Sarah Leavitt, Mark L. Chang
Low-Cost Stereo Vision On An Fpga, Chris A. Murphy, Daniel Lindquist, Ann Marie Rynning, Thomas Cecil, Sarah Leavitt, Mark L. Chang
Mark L. Chang
We present a low-cost stereo vision implementation suitable for use in autonomous vehicle applications and designed with agricultural applications in mind. This implementation utilizes the Census transform algorithm to calculate depth maps from a stereo pair of automotive-grade CMOS cameras. The final prototype utilizes commodity hardware, including a Xilinx Spartan-3 FPGA, to process 320times240 pixel images at greater than 150 frames per second and deliver them via a USB 2.0 interface.