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2014

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Articles 11101 - 11130 of 12299

Full-Text Articles in Physical Sciences and Mathematics

Skyrmionic Spin Seebeck Effect Via Dissipative Thermomagnonic Torques, Alexey Kovalev Jan 2014

Skyrmionic Spin Seebeck Effect Via Dissipative Thermomagnonic Torques, Alexey Kovalev

Department of Physics and Astronomy: Faculty Publications

We derive thermomagnonic torque and its “β-type” dissipative correction from the stochastic Landau-Lifshitz-Gilbert equation. The β-type dissipative correction describes viscous coupling between magnetic dynamics and magnonic current and it stems from spin mistracking of the magnetic order. We show that thermomagnonic torque is important for describing temperature gradient induced motion of skyrmions in helical magnets while dissipative correction plays an essential role in generating transverse Magnus force. We propose to detect such skyrmionic motion by employing the transverse spin Seebeck effect geometry.

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Electrospinning Applications Air Filtration And Superhydrophobic Materials, Negar Ghochaghi, Adetoun Taiwo Jan 2014

Electrospinning Applications Air Filtration And Superhydrophobic Materials, Negar Ghochaghi, Adetoun Taiwo

Graduate Research Posters

Electrospinning is a widely applicable technique that generates non-woven fibers in the micro and nano range. In this project two of its applications are highlighted namely filtration media and enhancement of wettability. The first project demonstrates that electrospinning can be used to produce new fiber filtration media with controlled microstructure. The bimodal and unimodal orthogonal and random filters were made and characterized against their filtration efficiency and pressure drop. Figure of Merit (FOM) was also calculated and discussed. It is shown that the FOM increases when the electrospun fibers are arranged into alternating layers of aligned course and fine fibers. …

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Using Spe And Hplc-Ms To Quantify And Identify Pharmaceutical Compounds In St. John's University Wastewater, Melissa E. Stuckey Jan 2014

Using Spe And Hplc-Ms To Quantify And Identify Pharmaceutical Compounds In St. John's University Wastewater, Melissa E. Stuckey

Honors Theses, 1963-2015

Pharmaceuticals in wastewater have become a concern of environmental toxicologists. An efficient method of discovering the concentrations of these pharmaceuticals in wastewater has not yet been produced. The method we developed includes an automated Solid Phase Extraction (SPE) procedure prior to injecting a sample of wastewater into the High Performance Liquid Chromatograph (HPLC) and Mass Spectrometer – Electrospray Ionization (MS-ESI). Three unknown peaks were identified on the HPLC and MS from wastewater obtained from the St. John’s Wastewater Treatment Plant in June 2013. Methods of analysis including NMR, GC-MS and IR have been used to determine the composition of these …

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Measuring Security: A Challenge For The Generation, Janusz Zalewski, Steven Drager, William Mckeever, Andrew J. Kornecki Jan 2014

Measuring Security: A Challenge For The Generation, Janusz Zalewski, Steven Drager, William Mckeever, Andrew J. Kornecki

Department of Electrical Engineering and Computer Science - Daytona Beach

This paper presents an approach to measuring computer security understood as a system property, in the category of similar properties, such as safety, reliability, dependability, resilience, etc. First, a historical discussion of measurements is presented, beginning with views of Hermann von Helmholtz in his 19th century work “Zählen und Messen”. Then, contemporary approaches related to the principles of measuring software properties are discussed, with emphasis on statistical, physical and software models. A distinction between metrics and measures is made to clarify the concepts. A brief overview of inadequacies of methods and techniques to evaluate computer security is presented, followed by …

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Evidentiary Power And Propriety Of Digital Identifiers And The Impact On Privacy Rights In The United States, Michael Losavio, Deborah Keeling Jan 2014

Evidentiary Power And Propriety Of Digital Identifiers And The Impact On Privacy Rights In The United States, Michael Losavio, Deborah Keeling

Journal of Digital Forensics, Security and Law

Media and network systems capture and store data about electronic activity in new, sometimes unprecedented ways; computational systems make for new means of analysis and knowledge development. These new forms offer new, powerful tactical tools for investigations of electronic malfeasance under traditional legal regulation of state power, particular that of Fourth Amendment limitations on police searches and seizures under the U.S. Constitution. But autonomy, identity and authenticity concerns with electronic data raise issues of public policy, privacy and proper police oversight of civil society. We examine those issues and their implications for digital and computational forensics

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Gis Modeling Of Elk Habitat Suitability In The North Cascades Of Washington State, Anna Yost Jan 2014

Gis Modeling Of Elk Habitat Suitability In The North Cascades Of Washington State, Anna Yost

All Master's Theses

The Washington State Department of Fish and Wildlife (WDFW) elk management goals are to adjust the distribution of elk on the landscape in the North Cascades to reduce negative impacts to private property while maintaining a healthy population of elk in the area. The goal of this study was to use custom Geographic Information System (GIS) elk habitat suitability models to model baseline elk habitat suitability in the 8,600 km2 North Cascades elk management area, and then evaluate how theoretical forage enhancement sites would affect habitat suitability. Prior to creating the baseline and proposed habitat suitability maps for the …

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Mixed Quantum/Classical Calculations Of Total And Differential Elastic And Rotationally Inelastic Scattering Cross Sections For Light And Heavy Reduced Masses In A Broad Range Of Collision Energies, Alexander Semenov, Dmitri Babikov Jan 2014

Mixed Quantum/Classical Calculations Of Total And Differential Elastic And Rotationally Inelastic Scattering Cross Sections For Light And Heavy Reduced Masses In A Broad Range Of Collision Energies, Alexander Semenov, Dmitri Babikov

Chemistry Faculty Research and Publications

The mixed quantum/classical theory (MQCT) for rotationally inelastic scattering developed recently [A. Semenov and D. Babikov, J. Chem. Phys.139, 174108 (2013)] is benchmarked against the full quantum calculations for two molecular systems: He + H2 and Na + N2. This allows testing new method in the cases of light and reasonably heavy reduced masses, for small and large rotational quanta, in a broad range of collision energies and rotational excitations. The resultant collision cross sections vary through ten-orders of magnitude range of values. Both inelastic and elastic channels are considered, as well as differential (over scattering angle) cross sections. In …

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Probing The Human Estrogen Receptor-Α Binding Requirements For Phenolic Mono- And Di-Hydroxyl Compounds: A Combined Synthesis, Binding And Docking Study, Christopher Mccullough, Terrence S. Neumann, Jayapal Reddy Gone, Zhengjie He, Christian Herrild, Julie Lukesh, Rajesh K. Pandey, William A. Donaldson, Daniel S. Sem Jan 2014

Probing The Human Estrogen Receptor-Α Binding Requirements For Phenolic Mono- And Di-Hydroxyl Compounds: A Combined Synthesis, Binding And Docking Study, Christopher Mccullough, Terrence S. Neumann, Jayapal Reddy Gone, Zhengjie He, Christian Herrild, Julie Lukesh, Rajesh K. Pandey, William A. Donaldson, Daniel S. Sem

Chemistry Faculty Research and Publications

Various estrogen analogs were synthesized and tested for binding to human ERα using a fluorescence polarization displacement assay. Binding affinity and orientation were also predicted using docking calculations. Docking was able to accurately predict relative binding affinity and orientation for estradiol, but only if a tightly bound water molecule bridging Arg394/Glu353 is present. Di-hydroxyl compounds sometimes bind in two orientations, which are flipped in terms of relative positioning of their hydroxyl groups. Di-hydroxyl compounds were predicted to bind with their aliphatic hydroxyl group interacting with His524 in ERα. One nonsteroid-based dihdroxyl compound was 1000-fold specific for ERβ over ERα, and …

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Controlled Release Kinetics In Hydroxy Double Salts: Effect Of Host Anion Structure, Stephen Majoni, Jeanne M. Hossenlopp Jan 2014

Controlled Release Kinetics In Hydroxy Double Salts: Effect Of Host Anion Structure, Stephen Majoni, Jeanne M. Hossenlopp

Chemistry Faculty Research and Publications

Nanodimensional layered metal hydroxides such as layered double hydroxides (LDHs) and hydroxy double salts (HDSs) can undergo anion exchange reactions releasing intercalated anions. Because of this, these metal hydroxides have found applications in controlled release delivery of bioactive species such as drugs and pesticides. In this work, isomers of hydroxycinnamate were used as model compounds to systematically explore the effects of anion structure on the rate and extent of anion release in HDSs. Following intercalation and subsequent release of the isomers, it has been demonstrated that the nature and position of substituent groups on intercalated anions have profound effects on …

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Discovering Spam On Twitter, Ioana-Alexandra Bara Jan 2014

Discovering Spam On Twitter, Ioana-Alexandra Bara

Theses and Dissertations

Twitter generates the majority of its revenue from advertising. Third parties pay to have their products advertised on Twitter through: tweets, accounts and trends. However, spammers can use Sybil accounts (fake accounts) [21] to advertise and avoid paying for it. Sybil accounts are highly active on Twitter performing advertising campaigns to serve their clients [5]. They aggressively try to reach a large audience to maximize their influence. These accounts have similar behavior if controlled by the same master. Most of their spam tweets include a shortened URL to trick users into clicking on it. Also, since they share resources with …

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Fabrication Of Nanoporous Gold And Biological Applications, Badharinadh Uppalapati Jan 2014

Fabrication Of Nanoporous Gold And Biological Applications, Badharinadh Uppalapati

Theses and Dissertations

FABRICATION OF NANOPOROUS GOLD AND BIOLOGICAL APPLICATIONS By Badharinadh Uppalapati A Dissertation submitted in partial fulfillment of the requirements for the degree of Master of Science at Virginia Commonwealth University. Virginia Commonwealth University, 2014 Major Director: Maryanne M. Collinson, Professor, Department of Chemistry Fabrication of nanoporous gold electrodes by dealloying Au:Ag alloys has attracted much attention in sensing applications. In the first part of this work, the electrochemical response of the redox active molecule, potassium ferricyanide, in a solution of bovine serum albumin in buffer, serum or blood was studied using nanoporous gold and comparisons made to planar gold. Nanoporous …

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Magnetic Properties Of Hematite (Α-Fe2o3) Nanorods, Samar A. Ghopry Jan 2014

Magnetic Properties Of Hematite (Α-Fe2o3) Nanorods, Samar A. Ghopry

Theses and Dissertations

At this study three samples of hematite nanorods were deposited on the silicon substrates with different varieties of glancing angle deposition techniques. One sample (S1) was prepared by using thermal deposition with partially ionized beam (PIB) and substrate rotation. The second sample (S2) was synthesized by using thermal deposition with PIB and no substrate rotation. The third sample (S3) was obtained by using E-beam deposition, PIB and rotating substrate. In addition, one sample of magnetite nanorods (S4) has been prepared in order to compare the magnetic properties of the two different iron oxides. S4 was prepared by using thermal deposition …

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Accurate Calculations Of Rotationally Inelastic Scattering Cross Sections Using Mixed Quantum/Classical Theory, Alexander Semenov, Dmitri Babikov Jan 2014

Accurate Calculations Of Rotationally Inelastic Scattering Cross Sections Using Mixed Quantum/Classical Theory, Alexander Semenov, Dmitri Babikov

Chemistry Faculty Research and Publications

For computational treatment of rotationally inelastic scattering of molecules, we propose to use the mixed quantum/classical theory, MQCT. The old idea of treating translational motion classically, while quantum mechanics is used for rotational degrees of freedom, is developed to the new level and is applied to Na + N2 collisions in a broad range of energies. Comparison with full-quantum calculations shows that MQCT accurately reproduces all, even minor, features of energy dependence of cross sections, except scattering resonances at very low energies. The remarkable success of MQCT opens up wide opportunities for computational predictions of inelastic scattering cross sections …

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Enantiomeric Selective Adsorption Of Amino Acid By Polysaccharide Composite Materials, Simon Duri, Chieu D. Tran Jan 2014

Enantiomeric Selective Adsorption Of Amino Acid By Polysaccharide Composite Materials, Simon Duri, Chieu D. Tran

Chemistry Faculty Research and Publications

A composite containing cellulose (CEL) and chitosan (CS) synthesized by a simple and recyclable method by using butylmethylimmidazolium chloride, an ionic liquid, was found to exhibit remarkable enantiomeric selectivity toward the adsorption of amino acids. The highest adsorption capacity and enantiomeric selectivity are exhibited by 100% CS. A racemic amino acid can be enantiomerically resolved by 100% CS in about 96–120 h. Interestingly, adsorption by 50:50 CEL/CS is more similar to that by 100% CS than to 100% CEL. Specifically, whereas 100% CEL has the lowest adsorption capacity and enantiomeric selectivity, 50:50 CEL/CS has sufficient enantiomeric selectivity to enable it …

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Split Strongly Abelian P-Chief Factors And First Degree Restricted Cohomology, Jorg Feldvoss, Salvatore Siciliano, Thomas Weigel Jan 2014

Split Strongly Abelian P-Chief Factors And First Degree Restricted Cohomology, Jorg Feldvoss, Salvatore Siciliano, Thomas Weigel

University Faculty and Staff Publications

In this paper we investigate the relation between the multiplicities of split strongly abelian p-chief factors of finite-dimensional restricted Lie algebras and first degree restricted cohomology. As an application we obtain a characterization of solvable restricted Lie algebras in terms of the multiplicities of split strongly abelian p-chief factors. Moreover, we derive some results in the representation theory of restricted Lie algebras related to the principal block and the projective cover of the trivial irreducible module of a finite-dimensional restricted Lie algebra. In particular, we obtain a characterization of finite-dimensional solvable restricted Lie algebras in terms of the second Loewy …

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Integrating Societal Perspectives And Values For Improved Stewardship Of A Coastal Ecosystem Engineer, Steven B. Scyphers, J. Steven Picou, Robert D. Brumbaugh, Sean P. Powers Jan 2014

Integrating Societal Perspectives And Values For Improved Stewardship Of A Coastal Ecosystem Engineer, Steven B. Scyphers, J. Steven Picou, Robert D. Brumbaugh, Sean P. Powers

University Faculty and Staff Publications

Oyster reefs provide coastal societies with a vast array of ecosystem services, but are also destructively harvested as an economically and culturally important fishery resource, exemplifying a complex social-ecological system (SES). Historically, societal demand for oysters has led to destructive and unsustainable levels of harvest, which coupled with multiple other stressors has placed oyster reefs among the most globally imperiled coastal habitats. However, more recent studies have demonstrated that large-scale restoration is possible and that healthy oyster populations can be sustained with effective governance and stewardship. However, both of these require significant societal support or financial investment. In our study, …

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Measuring Circuit Splits: A Cautionary Note, Aaron-Andrew P. Bruhl Jan 2014

Measuring Circuit Splits: A Cautionary Note, Aaron-Andrew P. Bruhl

Faculty Publications

A number of researchers have recently published new measures of the Supreme Court’s behavior in resolving conflicts in the lower courts. These new measures represent an improvement over prior, cruder approaches, but it turns out that measuring the Court’s resolutions of conflicts is surprisingly difficult. The aim of this methodological comment is to describe those difficulties and to establish several conclusions that follow from them. First, the new measures of the Court’s behavior are certainly imprecise and may reflect biased samples. Second, using the Supreme Court Database, which some studies rely on to assemble a dataset of cases resolving conflicts, …

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Is The Quantum State Real? An Extended Review Of Psi-Ontology Theorems, Matthew S. Leifer Jan 2014

Is The Quantum State Real? An Extended Review Of Psi-Ontology Theorems, Matthew S. Leifer

Mathematics, Physics, and Computer Science Faculty Articles and Research

Towards the end of 2011, Pusey, Barrett and Rudolph derived a theorem that aimed to show that the quantum state must be ontic (a state of reality) in a broad class of realist approaches to quantum theory. This result attracted a lot of attention and controversy. The aim of this review article is to review the background to the Pusey–Barrett–Rudolph Theorem, to provide a clear presentation of the theorem itself, and to review related work that has appeared since the publication of the Pusey–Barrett–Rudolph paper. In particular, this review: Explains what it means for the quantum state to be ontic …

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A Bayesian Approach To Compatibility, Improvement, And Pooling Of Quantum States, Matthew S. Leifer, Robert W. Spekkens Jan 2014

A Bayesian Approach To Compatibility, Improvement, And Pooling Of Quantum States, Matthew S. Leifer, Robert W. Spekkens

Mathematics, Physics, and Computer Science Faculty Articles and Research

In approaches to quantum theory in which the quantum state is regarded as a representation of knowledge, information, or belief, two agents can assign different states to the same quantum system. This raises two questions: when are such state assignments compatible? and how should the state assignments of different agents be reconciled? In this paper, we address these questions from the perspective of the recently developed conditional states formalism for quantum theory [1]. Specifically, we derive a compatibility criterion proposed by Brun, Finkelstein and Mermin from the requirement that, upon acquiring data, agents should update their states using a quantum …

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Modification Of Plasmonic Nano Structures' Absorption And Scattering Under Evanescent Wave Illumination Above Optical Waveguides Or With The Presence Of Different Material Nano Scale Atomic Force Microscope Tips, Gazi Mostafa Huda Jan 2014

Modification Of Plasmonic Nano Structures' Absorption And Scattering Under Evanescent Wave Illumination Above Optical Waveguides Or With The Presence Of Different Material Nano Scale Atomic Force Microscope Tips, Gazi Mostafa Huda

Theses and Dissertations--Electrical and Computer Engineering

The interaction of an evanescent wave and plasmonic nanostructures are simulated in Finite Element Method. Specifically, the optical absorption cross section (Cabs) of a silver nanoparticle (AgNP) and a gold nanoparticle (AuNP) in the presence of metallic (gold) and dielectric (silicon) atomic force microscope (AFM) probes are numerically calculated in COMSOL. The system was illuminated by a transverse magnetic polarized, total internally reflected (TIR) waves or propagating surface plasmon (SP) wave. Both material nanoscale probes localize and enhance the field between the apex of the tip and the particle. Based on the absorption cross section equation the author …

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The Second-Generation Z (Redshift) And Early Universe Spectrometer. I. First-Light Observation Of A Highly Lensed Local Ulirg Analog At High-Z, Carl Ferkinhoff, Drew Brisbin, Stephen Parshley, Thomas Nikola, Gordon J. Stacey, Justin Schoenwald, James L. Higdon, Sarah J.U. Higdon, Aprajit Verma, Dominik Riechers, Steven Hailey-Dunsheath, Karl M. Menten, Rolf Güsten, Axel Weiß, Kent Irwin, Hsiao M. Cho, Michael Niemack, Mark Halpern, Mandana Amiri, Matthew Hasselfield, D.V. Wiebe, Peter A.R. Ade, Carol E. Tucker Jan 2014

The Second-Generation Z (Redshift) And Early Universe Spectrometer. I. First-Light Observation Of A Highly Lensed Local Ulirg Analog At High-Z, Carl Ferkinhoff, Drew Brisbin, Stephen Parshley, Thomas Nikola, Gordon J. Stacey, Justin Schoenwald, James L. Higdon, Sarah J.U. Higdon, Aprajit Verma, Dominik Riechers, Steven Hailey-Dunsheath, Karl M. Menten, Rolf Güsten, Axel Weiß, Kent Irwin, Hsiao M. Cho, Michael Niemack, Mark Halpern, Mandana Amiri, Matthew Hasselfield, D.V. Wiebe, Peter A.R. Ade, Carol E. Tucker

Department of Physics and Astronomy Faculty Publications

We recently commissioned our new spectrometer, the second-generation z(Redshift) and Early Universe Spectrometer (ZEUS-2) on the Atacama Pathfinder Experiment telescope. ZEUS-2 is a submillimeter grating spectrometer optimized for detecting the faint and broad lines from distant galaxies that are redshifted into the telluric windows from 200 to 850 μm. It uses a focal plane array of transition-edge sensed bolometers, the first use of these arrays for astrophysical spectroscopy. ZEUS-2 promises to be an important tool for studying galaxies in the years to come because of its synergy with Atacama Large Millimeter Array and its capabilities in the short submillimeter …

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Modeling Effective Shade To Prioritize Riparian Restoration Efforts In The Johnson Creek Watershed, Or, Brittany Sahatjian Jan 2014

Modeling Effective Shade To Prioritize Riparian Restoration Efforts In The Johnson Creek Watershed, Or, Brittany Sahatjian

Environmental Science and Management Professional Master's Project Reports

The influence of stream temperature on the survival and reproductive success of anadromous salmonid populations has become an increasingly concerning issue in the Pacific Northwest. Enhancing the height, density and extent of riparian vegetation is widely accepted as one of the most effective strategies for reducing stream temperatures, while also providing numerous ancillary benefits. Effective shade is defined as the percentage of direct beam solar radiation attenuated and scattered by riparian vegetation before reaching the stream surface and is a commonly used criterion for choosing where to restore riparian vegetation. This project aims to prioritize sites for riparian restoration through …

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A Bayesian Model Of Fertility Decisions In Relationship To Female Labor Force Participation, Rebecca C. Wardrop Jan 2014

A Bayesian Model Of Fertility Decisions In Relationship To Female Labor Force Participation, Rebecca C. Wardrop

Senior Independent Study Theses

Due to the increasing number of women in the labor force, opportunity costs associated with labor force participation are becoming an important factor in fertility decisions. Further, these decisions are assumed to be dynamic as the opportunity costs change as a woman progresses through her career. A Bayesian statistical model , which allows the distribution of the likelihood of having children to be updated as information is gathered, lends itself to the dynamicity of the decision-making process. A generalized model for fertility decisions in terms of labor force participation is created. I also discuss potentials for implementation and furthering the …

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New Insights On Emergence From The Perspective Of Weak Values And Dynamical Non-Locality, Jeff Tollaksen Jan 2014

New Insights On Emergence From The Perspective Of Weak Values And Dynamical Non-Locality, Jeff Tollaksen

Mathematics, Physics, and Computer Science Faculty Articles and Research

In this article, we will examine new fundamental aspects of "emergence" and "information" using novel approaches to quantum mechanics which originated from the group around Aharonov. The two-state vector formalism provides a complete description of pre- and post-selected quantum systems and has uncovered a host of new quantum phenomena which were previously hidden. The most important feature is that any weak coupling to a pre- and post-selected system is effectively a coupling to a "weak value" which is given by a simple expression depending on the two-state vector. In particular, weak values, are the outcomes of so called "weak measurements" …

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A Not-So-Silent Spring: The Impacts Of Traffic Noise On Call Features Of The Bloody Bay Poison Frog (Mannophryne Olmonae), Catherine G. Clemmens Jan 2014

A Not-So-Silent Spring: The Impacts Of Traffic Noise On Call Features Of The Bloody Bay Poison Frog (Mannophryne Olmonae), Catherine G. Clemmens

Senior Independent Study Theses

No abstract provided.

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From Quanta To Qualia: How A Paradigm Shift Turns Into Science. Philosophy Study Vol. 4, Deepak Chopra, Menas Kafatos Jan 2014

From Quanta To Qualia: How A Paradigm Shift Turns Into Science. Philosophy Study Vol. 4, Deepak Chopra, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

Ever since the development of quantum mechanics in the first part of the 20th century, a new world view has emerged. Today, the physicalist objective assumption that objects exist independently of acts of observation has been challenged. The repercussions of this radical challenge to our common-sense perception of the world are far-reaching, although not yet generally realized. Here we argue that there is a complementary view to the way science which is being practiced, and that consciousness itself is primary and qualia form the foundation of experience. We outline the arguments of why the new science of qualia will tie …

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Stability Analysis Of Multimachine Thermal Power Systems Using The Nature-Inspired Modified Cuckoo Search Algorithm, Shivakumar Rangasamy, Panneerselvam Manickam Jan 2014

Stability Analysis Of Multimachine Thermal Power Systems Using The Nature-Inspired Modified Cuckoo Search Algorithm, Shivakumar Rangasamy, Panneerselvam Manickam

Turkish Journal of Electrical Engineering and Computer Sciences

The stability of modern interconnected thermal power systems is greatly affected by the presence of low-frequency inertial oscillations in the system, due to various forms of disturbances experienced. This paper provides an efficient damping solution to these oscillations based on nature-inspired modified cuckoo search algorithm-based controller design. The proposed controller design is formulated as a parameter optimization problem based on damping ratio and time-domain error deviations. The effectiveness of the proposed damping controller design is illustrated by performing the nonlinear time domain simulations of the test multimachine power systems under various operating conditions and disturbances. Moreover, an exhaustive comparative stability …

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Reliability-Based Maintenance Scheduling Of Generating Units In Restructured Power Systems, Mahmud Fotuhi Firuzabad, Farrokh Aminifar, Abbas Shahzadeh Jan 2014

Reliability-Based Maintenance Scheduling Of Generating Units In Restructured Power Systems, Mahmud Fotuhi Firuzabad, Farrokh Aminifar, Abbas Shahzadeh

Turkish Journal of Electrical Engineering and Computer Sciences

Maintenance scheduling of generating units in restructured power systems is a collaborative and interactive process between independent system operators (ISOs) and generating companies (GENCOs). The ISO should comply with GENCO maintenance preferences subject to targeted system reliability levels. This process might be multistage since the admission of all initial unit outage requests may threaten system reliability. Hence, the ISO accepts some proposals and determines alternatives for the remaining units. The GENCOs are then allowed to confirm the alternatives or revise them. In this paper the ISO problem of generating unit maintenance scheduling is tackled. The objective function is to minimize …

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Optimal Reactive Power Flow Solution In Multiterminal Ac-Dc Systems Based On Artificial Bee Colony Algorithm, Faruk Yalçin, Uğur Ari̇foğlu Jan 2014

Optimal Reactive Power Flow Solution In Multiterminal Ac-Dc Systems Based On Artificial Bee Colony Algorithm, Faruk Yalçin, Uğur Ari̇foğlu

Turkish Journal of Electrical Engineering and Computer Sciences

Active power loss optimization is one of the important goals in electrical power systems and it is provided by optimal reactive power flow (ORPF). In this study, a new approach for the solution of the ORPF in multiterminal AC-DC systems is proposed. This approach provides 3 main contributions. First, the convergence problem in the AC-DC power flow is solved. Second, the problem of getting stuck in local minima during the optimization process is overcome. Third, a better global optimum point is obtained for the ORPF. Active power loss optimization is implemented through the artificial bee colony (ABC) algorithm, which is …

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Comparison Of Ais And Fuzzy C-Means Clustering Methods On The Classification Of Breast Cancer And Diabetes Datasets, Seral Özşen, Rahi̇me Ceylan Jan 2014

Comparison Of Ais And Fuzzy C-Means Clustering Methods On The Classification Of Breast Cancer And Diabetes Datasets, Seral Özşen, Rahi̇me Ceylan

Turkish Journal of Electrical Engineering and Computer Sciences

Data reduction is an indispensable part of pattern classification processes in many cases. If the number of samples is excessive, sample reduction or data reduction algorithms can be used for an effective processing time and reliable successive results. Many methods have been used for data reduction. Fuzzy c-means is one of these methods and it is widely used in such applications as clustering algorithms. In this study, we applied a different clustering algorithm, an artificial immune system (AIS), for the data reduction process. We realized the performance evaluation experiments on the standard Chainlink and Iris datasets, while the main application …

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