Physical Sciences and Mathematics Commons^™

Unusual Resistance Hysteresis In N-Layer Graphene Field Effect Transistors Fabricated On Ferroelectric Pb(Zr0.2ti0.8)O3, X. Hong, J. Hoffman, A. Posadas, K. Zou, C. H. Ahn, J. Zhu

Xia Hong Publications

We have fabricated n-layer graphene field effect transistors on epitaxial ferroelectric Pb(Zr_0.2Ti_0.8)O₃ (PZT) thin films. At low gate voltages, PZT behaves as a high-k dielectric with k up to 100. An unusual resistance hysteresis occurs in gate sweeps at high voltages, with its direction opposite to that expected from the polarization switching of PZT. The relaxation of the metastable state is thermally activated, with an activation barrier of 50–110 meV and a time constant of 6 h at 300 K. We attribute its origin to the slow dissociation/recombination dynamics of water molecules adsorbed at …

Deposition Of High-Quality Hfo2 On Graphene And The Effect Of Remote Oxide Phonon Scattering, K. Zou, X. Hong, D. Keefer, J. Zhu

Xia Hong Publications

We demonstrate atomic layer deposition of high-quality dielectric HfO₂ films on graphene and determine the magnitude of remote oxide surface phonon scattering in dual-oxide structures. The carrier mobility in these HfO₂-covered graphene samples reaches 20 000 cm²/Vs at low temperature. Distinct contributions to the resistivity from surface optical phonons in the SiO₂ substrate and the HfO₂ overlayer are isolated. At 300 K, surface phonon modes of the HfO₂ film centered at 54 meV limit the mobility to approximately 20 000 cm²/Vs.

Water Current, Volume 42, No. 1, Winter 2010

Water Current Newsletter

Meet the Faculty (Tala Awada and Cody Knutson)
Above Average Precipitation Causes Groundwater Level Rises
$3.1 million NSF Grant Funds Innovative Grad Education Program
From the Interim Director: Getting a Feel for the Job With Lots Ahead for the Water Center
Free Water and Resources Lectures Continue
Planning Continues for Platte Basin Tour
October River Basins Symposium and Law Conference
Feds Mull Regulating Drugs in Water
Sediments and Emerging Contaminants: On the Menu and in the Air
Watching Water Consumption
Improved Site Adds New Features
Featured Partner: Tern and Plover Conservation Partnership
Wastewater Treatment Education Helps Protect Nebraska’s Water Resources …

Magnetodielectric Coupling Of Infrared Phonons In Single-Crystal Cu2oseo3, K. H. Miller, X. S. Xu, H. Berger, E. S. Knowles, D. J. Arenas, M. W. Meisel, D. B. Tanner

Xiaoshan Xu Papers

Reflection and transmission as a function of temperature (5–300 K) have been measured on a single crystal of the magnetoelectric ferrimagnetic compound Cu₂OSeO₃ utilizing light spanning the far infrared to the visible portions of the electromagnetic spectrum. The complex dielectric function and optical properties were obtained via Kramers-Kronig analysis and by fits to a Drude-Lortentz model. The fits of the infrared phonons show a magnetodielectric effect near the transition temperature (T_c~60 K). Assignments to strong far-infrared phonon modes have been made, especially those exhibiting anomalous behavior around the transition temperature.

Updated Bus Routes And Text Messaging System For San Luis Obispo Public Transit System Web Application, Matthew Bojorquez

Computer Engineering

As gas prices continue to rise and people become more aware of their carbon footprint, public transportation becomes more economically, environmentally, and sustainably viable. Currently, bus route timetables are available inside buses and at the transit center, but many users have little knowledge of how to read them. Therefore, to entice more people into using public transportation, we must make riding the buses less of a hassle for users. The Efficient Deployment of Advanced Public Transportation Systems (EDAPTS) system attempts to accomplish this. Building upon a web application designed by Jeff Tikkanen, a former Cal Poly student, that places bus …

Forest Roads Mapped Using Lidar In Steep Forested Terrain, Russell Alan White, Brian Dietterick, Thomas Mastin, Rollin Strohman

Natural Resources Management and Environmental Sciences

LiDAR-derived digital elevation models can reveal road networks located beneath dense forest canopy. This study tests the accuracy of forest road characteristics mapped using LiDAR in the Santa Cruz Mountains, CA. The position, gradient, and total length of a forest haul road were accurately extracted using a 1 m DEM. In comparison to a field-surveyed centerline, the LiDAR-derived road exhibited a positional accuracy of 1.5 m, road grade measurements within 0.53% mean absolute difference, and total road length within 0.2% of the field-surveyed length. Airborne LiDAR can provide thorough and accurate road inventory data to support forest management and watershed …

U-Singularity And T-Topos Theoretic Entropy, Goro C. Kato

Mathematics

We will give descriptions of u-singularities as we introduce the notion of t-topos theoretic entropies. The unifying methodology for a u-singularity is the universal mapping property of an inverse or direct limit. The qualitative, conceptual, and structural analyses of u-singularities are given in terms of inverse and direct limits of micro decompositions of a presheaf and coverings of an object in t-site in the theory of temporal topos.

Urcohomologies And Cohomologies Of N -Complexes, Naoya Hiramatsu, Goro Kato

Mathematics

For a general sequence of objects and morphisms, we construct two N-complexes. Then we can define cohomologies (i, k)-type of the N-complexes not only on a diagonal region but also in the triangular region. We obtain an invariant defined on a general sequence of objects and morphisms. For a short exact sequence of N-complexes, we get the associated long exact sequence generalizing the classical long exact sequence. Lastly, several properties of the vanishing cohomologies of N-complexes are given.

“Little Language” Project Modules, John Clements, Kathi Fisler

Computer Science and Software Engineering

Many computer science departments are debating the role of programming languages in the curriculum. These discussions often question the relevance and appeal of programming-languages content for today's students. In our experience, domain-specific, “little languages” projects provide a compelling illustration of the importance of programming-language concepts. This paper describes projects that prototype mainstream applications such as PowerPoint, TurboTax, and animation scripting. We have used these exercises as modules in non-programming languages courses, including courses for first year students. Such modules both encourage students to study linguistic topics in more depth and provide linguistic perspective to students who might not otherwise be …

Assessing Traceability Of Software Engineering Artifacts, Senthil Karthikeyan Sundaram, Jane Huffman Hayes, Alex Dekhtyar, E. Ashlee Holbrook

Computer Science and Software Engineering

The generation of traceability links or traceability matrices is vital to many software engineering activities. It is also person-power intensive, time-consuming, error-prone, and lacks tool support. The activities that require traceability information include, but are not limited to, risk analysis, impact analysis, criticality assessment, test coverage analysis, and verification and validation of software systems. Information Retrieval (IR) techniques have been shown to assist with the automated generation of traceability links by reducing the time it takes to generate the traceability mapping. Researchers have applied techniques such as Latent Semantic Indexing (LSI), vector space retrieval, and probabilistic IR and have enjoyed …

Partnering Enhanced-Nlp With Semantic Analysis In Support Of Information Extraction, Hisham Assal, John Seng, Franz J. Kurfess, Emily Schwarz, Kym Pohl

Computer Science and Software Engineering

Information extraction using Natural Language Processing (NLP) tools focuses on extracting explicitly stated information from textual material. This includes Named Entity Recognition (NER), which produces entities and some of the relationships that may exist among them. Intelligent analysis requires examining the entities in the context of the entire document. While some of the relationships among the recognized entities may be preserved during extraction, the overall context of a document may not be preserved. In order to perform intelligent analysis on the extracted information, we provide an ontology, which describes the domain of the extracted information, in addition to rules that …

Obtaining The C-27 California Landscape Contractors License, Nick Logan

Horticulture and Crop Science

The purpose of this project was to obtain the C-27 contractors license in California while still continuing education at Cal Poly San Luis Obispo, prior to graduation. Experience and verification of experience is extremely important in the process of obtaining the C-27. Without sufficient experience in landscape contracting, attempting to obtain the license is futile. Some people have the experience needed and this project is aimed at helping those people realize they can take advantage of their knowledge and become licensed. Even if those eligible are not prepared to own and operate a landscaping business, having the license can be …

Laurel Community Farmstand, Terje Johansen

Horticulture and Crop Science

The project was for us to come up with a temporary farmstand that would be set up to sell fruits and vegetables but mainly to draw people to the area to bring awareness that there were plans to build a development at that location. Our group, Dana Curtice, Robert Vasilieff and Terje Johansen met with the developers three times. New ideas and information were presented in the first two meetings. The third meeting was to present our final design.

Millimeter-Scale Contact Printing Of Aqueous Solutions Using A Stamp Made Out Of Paper And Tape, Chao-Min Cheng, Aaron D. Mazzeo, Jinlong Gong, Andres W. Martinez, Scott T. Phillips, Nina Jain, George M. Whitesides

Chemistry and Biochemistry

This communication describes a simple method for printing aqueous solutions with millimeter-scale patterns on a variety of substrates using an easily fabricated, paper-based microfluidic device (a paper-based ―stamp‖) as a contact printing device. The device is made from inexpensive materials, and it is easily assembled by hand; this method is thus accessible to a wide range of laboratories and budgets. A single device was used to print over 2500 spots in less than three minutes at a density of 16 spots per square centimetre. This method provides a new tool to pattern biochemicals—reagents, antigens, proteins, and DNA—on planar substrates. The …

Electrochemical Sensing In Paper-Based Microfluidic Devices, Zhihong Nie, Christian A. Nijhuis, Jinlong Gong, Xin Chen, Alexander Kumachev, Andres W. Martinez, Max Narovlyansky, George M. Whitesides

Chemistry and Biochemistry

This paper describes the fabrication and the performance of microfluidic paper-based electrochemical sensing devices (we call the microfluidic paper-based electrochemical devices, μPEDs). The μPEDs comprise paper-based microfluidic channels patterned by photolithography or wax printing, and electrodes screen-printed from conducting inks (e.g., carbon or Ag/AgCl). We demonstrated that the μPEDs are capable of quantifying the concentrations of various analytes (e.g., heavy-metal ions and glucose) in aqueous solutions. This low-cost analytical device should be useful for applications in public health, environmental monitoring, and the developing world.

Programmable Diagnostic Devices Made From Paper And Tape, Andres W. Martinez, Scott T. Phillips, Zhihong Nie, Chao-Min Cheng, Emanuel Carrilho, Benjamin J. Wiley, George M. Whitesides

Chemistry and Biochemistry

This paper describes three-dimensional microfluidic paper-based analytical devices (3-D μPADs) that can be programmed (postfabrication) by the user to generate multiple patterns of flow through them. These devices are programmed by pressing single-use ‘on’ buttons, using a stylus or a ballpoint pen. Pressing a button closes a small space (gap) between two vertically aligned microfluidic channels, and allows fluids to wick from one channel to the other. These devices are simple to fabricate, and are made entirely out of paper and double-sided adhesive tape. Programmable devices expand the capabilities of μPADs and provide a simple method for controlling the movement …

Numerical Investigation Of Aeroelastic Mode Distribution For Aircraft Wing Model In Subsonic Air Flow, Marianna A. Shubov, Stephen B. Wineberg, Robert Holt

Mathematics & Statistics

In this paper, the numerical results on two problems originated in aircraft wing modeling have been presented. The first problem is concerned with the approximation to the set of the aeroelastic modes, which are the eigenvalues of a certain boundary-value problem. The affirmative answer is given to the following question: can the leading asymptotical terms in the analytical formulas be used as reasonably accurate description of the aeroelastic modes? The positive answer means that these leading terms can be used by engineers for practical calculations. The second problem is concerned with the flutter phenomena in aircraft wings in a subsonic, …

Blue Carbon: The Role Of Healthy Oceans In Binding Carbon, Christian Nellemann, Emily Corcoran, Carlos M. Duarte, Cassandra De Young, Luciano E. Fonseca, Gabriel Grimsdith

Center for Coastal and Ocean Mapping

No abstract provided.

Mechanical Sensorless Maximum Power Tracking Control For Direct-Drive Pmsg Wind Turbines, Xu Yang, Xiang Gong, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

Wind turbine generators (WTGs) are usually equipped with mechanical sensors to measure wind speed and rotor position for system control, monitoring, and protection. The use of mechanical sensors increases the cost and hardware complexity and reduces the reliability of the WTG systems. This paper proposes a mechanical sensorless maximum power tracking control for wind turbines directly driving permanent magnetic synchronous generators (PMSGs). In the proposed algorithm, the PMSG rotor position is estimated from the measured stator voltages and currents by using a sliding mode observer (SMO). The wind turbine shaft speed is estimated from the PMSG back electromotive force (EMF) …

Communication With Aboveground Devices In Wireless Underground Sensor Networks: An Empirical Study, Agnelo R. Silva, Mehmet C. Vuran

CSE Conference and Workshop Papers

Wireless Underground Sensor Networks (WUSNs) consist of wirelessly connected underground sensor nodes that communicate untethered through soil. WUSNs have the potential to impact a wide variety of novel applications including intelligent irrigation, environment monitoring, border patrol, and assisted navigation. Although its deployment is mainly based on underground sensor nodes, a WUSN still requires aboveground devices for data retrieval, management, and relay functionalities. Therefore, the characterization of the bi-directional communication between a buried node and an aboveground device is essential for the realization of WUSNs. In this work, empirical evaluations of underground-to-aboveground (UG2AG) and aboveground-to-underground (AG2UG) communication are presented. More specifically, …

A First Practical Algorithm For High Levels Of Relational Consistency, Shant Karakashian, Robert J. Woodward, Christopher Reeson, Berthe Y. Choueiry, Christian Bessiere

CSE Conference and Workshop Papers

•Introduction

•Relational Consistency R(*,m)C :

–Definition, Naïve algorithm, Properties

•Preliminaries: Dual CSP

•Our Approach

–Algorithm

–Index-Tree Data Structure

–Advantages

•A weakened version of R(*,m)C: wR(*,m)C

•Experimental Evaluations

•Conclusions & Future Work

A First Practical Algorithm For High Levels Of Relational Consistency, Shant Karakashian, Robert J. Woodward, Christopher Reeson, Berthe Y. Choueiry, Christian Bessiere

CSE Conference and Workshop Papers

Consistency properties and algorithms for achieving them are at the heart of the success of Constraint Programming. In this paper, we study the relational consistency property R(*,m)C, which is equivalent to m-wise consistency proposed in relational databases. We also define wR(*,m)C, a weaker variant of this property. We propose an algorithm for enforcing these properties on a Constraint Satisfaction Problem by tightening the existing relations and without introducing new ones. We empirically show that wR(*,m)C solves in a backtrackfree manner all the instances of some CSP benchmark classes, thus hinting at the tractability …

Annealing Temperature And Initial Iron Valence Ratio Effects On The Structural Characteristics Of Nanoscale Nickel Zinc Ferrite, S. Calvin, M. D. Schultz, L. Glowzenski, E. E. Carpenter

Chemistry Publications

Nickelzincferrite (NZFO) nanoparticles were synthesized via a reverse micelle method with a nonionic surfactant. Three different initial Fe3+/Fe2+ ratios were employed along with three different firing temperatures (200, 500, 1000 °C) to investigate the effects on the NZFO system. Extended x-rayabsorption fine structure (EXAFS) results reveal zinc loss at high annealing temperatures; at 1000 °C, the loss is nearly total for Fe3+/Fe2+ ratios other than 10:90. Annealing at 500 °C, however, appears necessary for fully incorporating the zinc and nickel into the spinel phase. The best nanoferrite was thus obtained using an initial Fe3+/Fe2+ ratio of 10:90 and a moderate …

Localized Surface Plasmon Resonance Enhanced Magneto-Optical Activity In Core-Shell Fe-Ag Nanoparticles, L. Wang, K. Yang, C. Clavero, A. J. Nelson, K. J. Carroll, E. E. Carpenter, R. A. Lukaszew

Chemistry Publications

Metallic nanoparticles (NPs) are suitable platforms for miniaturized biosensing based on their optical and magneto-opticalproperties. It is possible to enhance the sensitivity of specific kinds of NPs by exploiting their optical and magneto-opticalproperties under suitable external magnetic field modulation. Here, the magneto-opticalproperties of Fe–Ag core-shell ferromagnet-noble metal NPs have been investigated as a function of the incident light frequency. For Fe–Ag NPs with a concentration ratio around 25:75, an optical absorption band centered at 3 eV due to localized surface plasmon resonance (LSPR) excitation is observed. A strong enhancement of the Faraday rotation is also observed, greatly exceeding the value …

Dual Mode Nanoparticles: Cds Coated Iron Nanoparticles, F. N. Radwan, K. J. Carroll, E. E. Carpenter

Chemistry Publications

Reverse micelles can be used in a sequential fashion to make core-shell nanoparticles. Using this technique it is possible to make a magnetic quantum dot, by coating an iron core with a cadmium sulfide shell. Transmission electron microscopy indicated core-shell morphology and narrow size distribution of the obtained particles. Collectively, x-ray powder diffraction and x-ray photoelectron spectroscopy verified the presence of cadmium sulfide on the surface of the nanoparticles. Optical properties of the coated particles were demonstrated using fluorescence spectroscopy. A vibrating sample magnetometer was used to determine magnetic properties. Dual mode cadmium sulfide coatediron core-shell nanoparticles make unique candidates …

High Magnetization Aqueous Ferrofluid: A Simple One-Pot Synthesis, Kyler J. Carroll, Michael D. Schultz, Panos P. Fatouros, Everett E. Carpenter

Chemistry Publications

A one-step polyol method was utilized to prepare a stable aqueous iron/iron oxide ferrofluid. The dried powders were characterized by x-ray diffraction, electron microscopy, x-ray absorption spectroscopy, and vibrating sample magnetometry for the determination of phase, morphology, and magnetic properties. To show its potential for imaging applications, the ferrofluid was also investigated as a magnetic resonance imaging contrast agent.

Annealing Of Amorphous Fexco100-X Nanoparticles Synthesized By A Modified Aqueous Reduction Using Nabh4, Kyler J. Carroll, Daniel M. Hudgins, L. W. Brown Iii, S. D. Yoon, D. Heiman, V. G. Harris, Everett E. Carpenter

Chemistry Publications

FexCo100−x nanoparticles were synthesized by aqueous reduction in iron (II) sulfate and cobalt (II) sulfate using sodium borohydride and sodium citrate. The initial concentrations of iron and cobalt were varied while maintaining an overall metal concentration of 4.60 mM. Increasing the cobalt content from 0 to 100 at. % decreased the magnetization saturation from 152 to 48 emu/g, as determined by room temperature vibrating sample magnetometry. Annealing the samples at 450 and 600 °C showed an increase in crystallite size. Powder x-ray diffraction and transmission electron microscopy was performed to determine the phases and morphology of the materials.

Nonclassical Crystallization Of Amorphous Iron Nanoparticles By Radio Frequency Methods, Kyler J. Carroll, J. A. Pitts, Kai Zhang, A. K. Pradhan, E. E. Carpenter

Chemistry Publications

Amorphousironnanoparticles were synthesized using an aqueous reduction in iron(II) sulfate with sodium borohydride and sodium citrate. Various radio frequency (rf) exposure times were investigated in order to determine trends in nonclassical crystallization. RF times from 15 to 300 s revealed an increase in crystallite size from 5 to 60 nm, as determined by powde rx-ray diffraction. Also, solvent optimization revealed that ethanol produced the largest trends for increasing crystallite size without total oxidation of the samples. Magnetic characterization by room temperature vibrating sample magnetometry and high resolution transmission microscopy was performed to verify magnetic properties and particle morphology.

The Growth And Evolution Of Thin Oxide Films On Δ-Plutonium Surfaces, Harry G. García Flores, David L. Pugmire

Chemistry Department: Faculty Publications

The common oxides of plutonium are the dioxide (PuO₂) and the sesquioxide (Pu₂O₃). The nature of an oxide on plutonium metal under air at room temperature is typically described as a thick PuO₂ film at the gas-oxide interface with a thinner Pu₂O₃ film near the oxide-metal substrate interface. In a reducing environment, such as ultra high vacuum, the dioxide (Pu⁴⁺; O/Pu=2.0) readily converts to the sesquioxide (Pu³⁺; O/Pu=1.5) with time. In this work, the growth and evolution of thin plutonium oxide films is studied with x-ray …

Self-Assembled Heteroleptic Chiral Ligands, Asymmetric Catalyst Systems And Methods, James M. Takacs

Chemistry Department: Faculty Publications

A method of synthesizing a heteroleptic, multiple metal containing metallocyclic catalyst, particularly Suited for asymmetric catalysis, comprising combining a plurality of plural functional group-containing, monodentate ligands of complementary chirality, said plural functional groups being tethered to each other by tethers in the presence of a scaffold structural metal Ms or derivative thereof, wherein at least one functional group on each ligand combines to ligate M to form a bidentate, M_s centered ligand scaffold containing the remaining functional groups and combining said bidentate ligand scaffold with a catalytic metal M_c or derivative thereof whereby the remaining functional groups combine …