Physical Sciences and Mathematics Commons^™

Low-Frequency Noise In N-Gan With High Electron Mobility, M. E. Levinshtein, S. L. Rumyantsev, David C. Look, Richard J. Molnar, M. A. Khan, G. Simin, V. Adivarahan, M. S. Shur

Physics Faculty Publications

We report on the results of measurements of low frequency noise in n-type gallium nitride (GaN) grown on sapphire with 300 K electron mobility of 790 cm²/V s. The noise spectra have the form of 1/f noise with a Hooge parameter α of approximately 5×10⁻². This value of α is two orders of magnitude smaller than that observed before in n-GaN. The obtained results show that the level of flicker noise in GaN, just like that in GaAs and Si, strongly depends on the structural perfection of the material (the amplitude of the …

Peak-To-Mean Power Control In Ofdm, Golay Complementary Sequences, And Reed–Muller Codes, James A. Davis, Jonathan Jedwab

Department of Math & Statistics Faculty Publications

We present a range of coding schemes for OFDM transmission using binary, quaternary, octary, and higher order modulation that give high code rates for moderate numbers of carriers. These schemes have tightly bounded peak-to-mean envelope power ratio (PMEPR) and simultaneously have good error correction capability. The key theoretical result is a previously unrecognized connection between Golay complementary sequences and second-order Reed–Muller codes over alphabets ℤ_2^h. We obtain additional flexibility in trading off code rate, PMEPR, and error correction capability by partitioning the second-order Reed–Muller code into cosets such that codewords with large values of PMEPR are isolated. …

Runoff From Fescue Plots Treated With Trimec, Cristopher G. Moss, Dwayne R. Edwards, Stephen R. Workman, R. Michael Williams

Biosystems and Agricultural Engineering Faculty Publications

Runoff of herbicides can promote adverse impacts in receiving waters. The objective of this study was to assess the effects of rainfall delay, herbicide application rate, rainfall intensity, and pre-application rainfall on runoff of TRIMEC (a combination of 2,4-D, dicamba, and mecoprop), a herbicide that is commonly used in central Kentucky. The levels of rainfall delay were 0, 2, and 4 d following application; and the levels of herbicide application rate were 0, 0.5, 1 and 2 times the recommended rate. Simulated rainfall was applied at intensities of 64, 102, and 140 mm h^-1; and the depths of …

The Pulsation Properties Of Procyon A, Brian Chaboyer, P. Demarque, D. B. Guenther

Dartmouth Scholarship

A grid of stellar evolution models for Procyon A has been calculated. These models include the best physics available to us (including the latest opacities and equation of state) and are based on the revised astrometric mass of Girard et al. Models were calculated with helium diffusion and with the combined effects of helium and heavy-element diffusion. Oscillation frequencies for l = 0, 1, 2, and 3 p-modes and the characteristic period spacing for the g-modes were calculated for these models. We find that g-modes are sensitive to model parameters that effect the structure of the core, …

Crossover Photonic Switching Network With Cmos/Seed Smart Pixel Device And 2d Optical Fiber Bundle Array, Fengguang Luo, Mingcui Cao, Qiaoyan Hu, Anjun Wan, Jun Xu, Cong Deng, Deming Liu

Electro-Optics and Photonics Faculty Publications

A 16 X 16 Crossover photonic switching network with hybrid integrated CMOS/SEED smart pixel device and 2D optical fiber bundle array I/O access device is reported in this paper. SEEd array devices ar used as light receivers and transmitters, while CMOS devices make efficient logical processing. 4 X 40 2D multilayer optical fiber bundle arrays are fabricated and are used as I/O access devices in the crossover photonic switching network. The center to center spacing between adjacent optical fibers in the same layer of the fiber array is 125micrometers , and the spacing between adjacent layers is 250micrometers . Displacing …

Intersecting Chains In Finite Vector Spaces, Eva Czabarka

Faculty Publications

We prove an Erdős–Ko–Rado-type theorem for intersecting k-chains of subspaces of a finite vector space. This is the q-generalization of earlier results of Erdős, Seress and Székely for intersecting k-chains of subsets of an underlying set. The proof hinges on the author's proper generalization of the shift technique from extremal set theory to finite vector spaces, which uses a linear map to define the generalized shift operation. The theorem is the following.

For c = 0, 1, consider k-chains of subspaces of an n-dimensional vector space over GF(q), such that the smallest subspace in any chain has dimension at least …

Kinematic Analysis Of Spatial Fixed-Axes Pairs Using Configuration Spaces, Ku-Jin Kim, Elisha Sacks, Leo Joskowicz

Department of Computer Science Technical Reports

No abstract provided.

Compression Of Biological Sequences By Greedy Off-Line Textual Subsitution, Alberto Apostolico, Stefano Lonardi

Department of Computer Science Technical Reports

No abstract provided.

Optimal Discovery Of Subword Associations In Strings, Alberto Apostolico, Giorgio Satta

Department of Computer Science Technical Reports

No abstract provided.

Data Organization Issues For Location-Dependent Queries In Mobile Computing, Sunjay Kumar Madria, Bharat Bhargava, Evaggelia Pitoura, Vijay Kumar

Department of Computer Science Technical Reports

No abstract provided.

Performance Evaluation Of Multiple Time Scale Tcp Under Self-Similar Traffic Conditions, Tsunyi Tuan, Kihong Park

Department of Computer Science Technical Reports

No abstract provided.

On Learning Probabilistic Automata, Alberto Apostolico

Department of Computer Science Technical Reports

No abstract provided.

Performance Evaluation Of Cpu Isolation Miechanisms In A Multithreaded Os Kernel, David K.Y. Yau

Department of Computer Science Technical Reports

No abstract provided.

Leveraging Legacy Scientific Software With Mobile Agent Technology, Shanhani Markus, Elias N. Houstis

Department of Computer Science Technical Reports

No abstract provided.

To Host A Legacy System To The Web, Miguel Angel Bustamante

Student Work

The dramatic improvements in global interconectivity due to intranets, extranets and the Internet has led to many enterprises to consider migrating legacy systems to a web based systems. While data remapping is relatively straightforward in most cases, greater challenges lie in adapting legacy application software. This research effort describes an experiment in which a legacy system is migrated to a web-client/server environment. First, this thesis reports on the difficulties and issues arising when porting a legacy system International Invoice (IIMM) to a web-client/server environment. Next, this research analyzes the underlying issues, and offer cautionary guidance to future migrators and finally …

Coordinate Realizations Of Deformed Lie Algebras With Three Generator, Ranabir Dutt, Asim Gangopadhyaya, C. Rasinariu, Uday P. Sukhatne

Physics: Faculty Publications and Other Works

Differential realizations in coordinate space for deformed Lie algebras with three generators are obtained using bosonic creation and annihilation operators satisfying Heisenberg commutation relations. The unified treatment presented here contains as special cases all previously given coordinate realizations of so(2,1), so(3), and their deformations. Applications to physical problems involving eigenvalue determination in nonrelativistic quantum mechanics are discussed.

Slow-Binding Inhibition Of The Aminopeptidase From Aeromonas Proteolytica By Peptide Thiols: Synthesis And Spectroscopic Characterization, Kristi M. Huntington, David L. Bienvenue, Yaoming Wei, Brian Bennett, Richard C. Holz, Dehua Pei

Physics Faculty Research and Publications

Peptide-derived thiols of the general structure N-mercaptoacyl-leucyl-p-nitroanilide (1a−c) were synthesized and found to be potent, slow-binding inhibitors of the aminopeptidase from Aeromonas proteolytica (AAP). The overall potencies (K_I*) of these inhibitors against AAP range from 2.5 to 57 nM exceeding that of the natural product bestatin and approaching that of amastatin. The corresponding alcohols (2a−b) are simple competitive inhibitors of much lower potencies (K_I = 23 and 360 μM). These data suggest that the free thiols are involved in the formation of the E·I …

Stabilization Of Polystyrene By Friedel-Crafts Chemistry: Effect Of Position Of Alcohol And The Catalyst, Jin Zhu, Michael A. Mckinney, Charles Wilkie

Chemistry Faculty Research and Publications

Polystyrene has been copolymerized with 4-vinylbenzyl alcohol, 4-(2-hydroxyethyl)styrene, and 4-(3-hydroxypropyl)styrene and it has been shown that thermal cross-linking of these copolymers is dependent upon the alcohol content. When the alcohol content is low, no thermal cross-linking is observed. When various phosphate esters are present as catalysts with these low alcohol content copolymers, cross-linking is observed at temperatures of about 250°C but not at lower temperatures. Cross-linking enhances the thermal stability of the copolymers. Studies of the thermal stability of the copolymers and their blends with the catalysts have been performed using thermogravimetric analysis and thermogravimetric analysis coupled to Fourier transform …

On-Road Remote Sensing Of Automobile Emissions In The Phoenix Area: Year 1, Gary A. Bishop, Sajal S. Pokharel, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

Laser-Induced Stabilization Of Autoionizing States, Heider N. Ereifej, J. Greg Story

Physics Faculty Research & Creative Works

Stabilization of autoionizing states of barium by laser-induced, stimulated emission of light is demonstrated. Relative to purely flourescent stabilization, the data clearly show an enhancement of the stabilization process for laser pulses short compared to the flourescent lifetime of the autoionizing states. Shakeup spectra in which the principal quantum number of both electrons changes during the stimulated emission process are also clearly demonstrated.

Intensity Dependence Of Plateau Structures In Laser-Assisted X-Ray–Atom Scattering Processes, Dejan B. Miloševic, Anthony F. Starace

Anthony F. Starace Publications

The dependence on laser intensity of recently discovered plateau structures in laser-assisted x-ray–atom scattering, both with and without a static electric field present, is analyzed. Using the “three-step” model and the strong-field approximation we demonstrate a connection between laser-assisted, x-ray–atom scattering and high-order harmonic generation: For high laser-field intensities without a static field present, both processes have plateaus whose energies extend to the cutoff value 3.17U_p, where U_p is the ponderomotive potential energy. For x-ray–atom scattering in the presence of a static electric field we show that at high laser-field intensities two plateaus appear: One is …

Measurement Of B Quark Fragmentation Fractions In The Production Of Strange And Light B Mesons In Pp̅ Collisions At √S =1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

A new technique to measure the ratio of b quark fragmentation fractions in pp̅ collisions is described. Using a 70-pb^-1 sample of low-mass dimuon trigger data recorded with the Collider Detector at Fermilab, we identify B mesons by observing the double semileptonic decays b→cμX with c→sμ X. By counting the numbers of K*(892) ⁰, K*(892) ¹, and Φ (1020) mesons produced in association with these muon pairs, we measure the ratio of strange to nonstrange B meson production to be f_s /( f_u+ i>f_d)=[21.0±3.6(stat) _{-3.0 …}

Investigation Of Image Feature Extraction By A Genetic Algorithm, Steven P. Brumby, James P. Theiler, Simon J. Perkins, Neal R. Harvey, John J. Szymanski, Jeffrey J. Bloch, Melanie Mitchell

Computer Science Faculty Publications and Presentations

We describe the implementation and performance of a genetic algorithm which generates image feature extraction algorithms for remote sensing applications. We describe our basis set of primitive image operators and present our chromosomal representation of a complete algorithm. Our initial application has been geospatial feature extraction using publicly available multi-spectral aerial-photography data sets. We present the preliminary results of our analysis of the efficiency of the classic genetic operations of crossover and mutation for our application, and discuss our choice of evolutionary control parameters. We exhibit some of our evolved algorithms, and discuss possible avenues for future progress.

An Elliptic Partial Differential Equation With A Symmetrical Almost Periodic Term, Gregory S. Spradlin

Publications

In [STT], a Hamiltonian system of the form (1.0)− u′′+ u= h (t)∇ F (u) was studied, where h is an almost periodic (defined in a moment) function, and F: RN→ R a “superquadratic” potential. That is, F (q) behaves like q to a power greater than 2, with F (q)/| q| 2→ 0 as| q|→ 0 and F (q)/| q| 2→∞ as| q|→∞. For example, F (q)=| q| p− 1q with p> 1 would qualify. The authors found that (1.0) must have a nonzero solution homoclinic to zero. Since this result, many papers (see [CMN],[R1], and [ACM], for example) …

A Singularly Perturbed Elliptic Partial Differential Equation With An Almost Periodic Term, Gregory S. Spradlin

Publications

In [STT], a Hamiltonian system of the form (1. 0)− u+ u= h (t)∇ F (u) was studied, where h is an almost periodic (defined in a moment) function, and F: Rn→ R a “superquadratic” potential. That is, F (q) behaves like q to a power greater than 2, with F (q)/| q| 2→ 0 as| q|→ 0 and F (q)/| q| 2→∞ as| q|→∞. For example, F (q)=| q| p− 1q with p> 1 would qualify. The authors found that (1.0) must have a nonzero solution homoclinic to zero. Since this result, many papers (see [CMN],[R1], and [ACM], for …

Zbroker: A Query Routing Broker For Z39.50 Databases, Yong Lin, Jian Xu, Ee Peng Lim, Wee-Keong Ng

Research Collection School Of Computing and Information Systems

A query routing broker is a software agent that determines from a large set of accessing information sources the ones most relevant to a user's information need. As the number of information sources on the Internet increases dramatically, future users will have to rely on query routing brokers to decide a small number of information sources to query without incurring too much query processing overheads. In this paper, we describe a query routing broker known as ZBroker developed for bibliographic database servers that support the Z39.50 protocol. ZBroker samples the content of each bibliographic database by using training queries and …

Mpeg-4 Systems And Applications, Hari Kalva, Lai-Tee Cheok, Alexandros Eleftheriadis

Research Collection School Of Computing and Information Systems

MPEG-4, under the auspices of the ISO, is specifying tools to enable object-based audio-visual presentations [3]. These include tools to encode individual objects, compose presentations with objects, store these object-based presentations and access these presentations in a distributed manner over networks. The main distinguishing feature of object-based audio-visual presentations is the scene composition at the user terminal. The objects that are part of a scene are composed and displayed at the user end as opposed to encoding the composed scenes as is done in the case of MPEG-2. Such object-based representation and presentation has several benefits including compression efficiency and …

Vegetation Trend In The East Kimberley Region : An Analysis Of Ground Monitoring Data From 1991-1998, Noelene Duckett, Paul Novelly, Ian Watson

Research Reports

This document summarises the analyses carried out on the ground monitoring data from the Kimberley region of Western Australia as part of the Natural Heritage Trust project 953024 - ‘'Development of Information Products for Reporting Rangeland Changes.”

Bulletin 4396 - Byenup Hill Focus Catchment Benefit: Cost Analysis, Allan Herbert

Bulletins 4000 -

The main text of this document concentrates on the costs of the proposed strategies, and the on-farm financial benefits from forecast production changes - in particular the production differences between the 'do nothing' and 'with strategy' scenarios.

Members of the catchment group indicated however that their main focus was on preserving their capital base. Hence some discussion of the values of land lost to salt and premiums/discounts for 'landcared' vs 'unlandcared' land appears later in the report. Economics literature suggests that including changes in land values into these analyses is incorrect. It is argued that production differences are actually captured …

Resonant Enhancement Of Relativistic Electron Fluxes During Geomagnetically Active Periods, I Roth, M Temerin, M K. Hudson

Dartmouth Scholarship

The strong increase in the ̄ux of relativistic electrons during the recovery phase of magnetic storms and during other active periods is investigated with the help of Hamiltonian formalism and simulations of test electrons which interact with whistler waves. The intensity of the whistler waves is enhanced signi®cantly due to injection of 10±100 keV electrons during the substorm. Electrons which drift in the gradient and curvature of the magnetic ®eld generate the rising tones of VLF whistler chorus. The seed population of relativ- istic electrons which bounce along the inhomogeneous magnetic ®eld, interacts resonantly with the whistler waves. Whistler wave …