Physical Sciences and Mathematics Commons^™

What To Do On Your Summer Vacation, Alissa Crans

Mathematics, Statistics and Data Science Faculty Works

Summer vacation brings back fond memories: playing frisbee in the park, bike-riding till dusk, sipping lemonade on the porch with Grandpa, collecting shells at the beach, solving that difficult math problem you've been working on for the past several weeks. Wait a minute, you say? Many mathematics majors don't realize that numerous summer opportunities exist (many of them paid, so you don't need to get that job bagging groceries, too). A math program provides intellectual stimulation during those hot summer months, bringing your level of concentration up from swatting flies and applying sunscreen. The following descriptions are from actual participants …

The Hadamard Core Of The Totally Nonnegative Matrices, Alissa Crans

Mathematics, Statistics and Data Science Faculty Works

An m-by- n matrix A is called totally nonnegative if every minor of A is nonnegative. The Hadamard product of two matrices is simply their entry-wise product. This paper introduces the subclass of totally nonnegative matrices whose Hadamard product with any totally nonnegative matrix is again totally nonnegative. Many properties concerning this class are discussed including: a complete characterization for min{m,n}<4 >; a characterization of the zero–nonzero patterns for which all totally nonnegative matrices lie in this class; and connections to Oppenheim's inequality.

Measurement Of The Gluon Parton Distribution Function At Small X With Neutrino Telescopes, Gabriele U. Varieschi

Physics Faculty Works

We analyze the possibility that neutrino telescopes may provide an experimental determination of the slope λ of the gluon distribution in the proton at momentum fractions x smaller than the accelerator reach. The method is based on a linear relation between λ and the spectral index ~slope! of the down-going atmospheric muon flux above 100 TeV, for which there is no background. Considering the uncertainties in the charm production cross section and in the cosmic ray composition, we estimate the error on the measurement of l through this method, excluding the experimental error of the telescopes, to be ±0.2.

On The Existence Of Finite Type Link Homotopy Invariants, Blake Mellor, Dylan Thurston

Mathematics, Statistics and Data Science Faculty Works

We show that for links with at most 5 components, the only finite type homotopy invariants are products of the linking numbers. In contrast, we show that for links with at least 9 components, there must exist finite type homotopy invariants which are not products of the linking numbers. This corrects previous errors of the first author.

Development Of Solid State Uv Detector Using Commercial Tld And Ln2o3:Re3+ (Ln=Y, La, Gd; Re=Tm, Tb, Eu, Er, Pr), Abdullah Mohd. Noh

Student Works (2000-2009)

Dosimetry of terrestrial ultraviolet (UV) using thermoluminescence (TL) material is an attractive method for a number of reasons. Such as the low cost per phosphor, the possibility to produce them in laboratory with simple facilities, the absence of any associated electronics at the site of measurement and the small size of solid phosphors which can also be used in personal dosimetry. In this research, we are searching for a suitable lanthanide oxide powder and commercial TLD material that can detect solar UV radiation using intrinsic method. The investigated lanthanide oxide powders include Gd₂O₃, La₂O₃ and Y₂O₃ doped with different rare …

Mpls Vpn Simulation Using Mp-Ibgp, Tan Fong Ang

Student Works (2000-2009)

As Internet traffic continues to increase, companies are demanding greater speeds and better services to disseminate information to their customers, partners and employees. In order to provide reliable services and to support a variety of secure communications among a wide range of locations, Multiprotocol Label Switching Virtual Private Network (MPLS VPN) has been introduced. MPLS is an emerging technology that aims to address many of the existing issues associated with packet forwarding in today's internetworking environment. Whereas, VPN provides secure private connections through public infrastructure amongst multiple locations. MPLS­ based VPN provides isolation. security, simplified routing, easier provisioning as well …

Network Simulation And Performance Evalution Of Ip Multicast Using Pim-Dm In Umjanetsim, Jui Hiangh Teoh

Student Works (2000-2009)

The demand for multicast capabilities in IP networks is growing very rapidly. New applications that take advantage of IP Multicast are being introduced constantly. Therefore, IP Multicast is regarded as one of the most important technologies in IP networks today. This dissertation focuses on the simulation and performance evaluation of IP Multicast using Protocol Independent Multicast- Dense Mode (PIM-OM) as the multicast routing protocol. The simulation is executed in a network simulator named UMJaNetSim, where custom components are built in order to simulate IP Multicast. First, the advantages and applications of IP Multicast, multicast addressing, Internet Group Management Protocol (IGMP), …

Structural, Electronic, And Magnetic Properties Of Lani₅₋ₓtₓ (T = Fe, Mn) Compounds, Jinbo Yang, Chiu-Ying Tai, G. K. Marasinghe, George Daniel Waddill, Oran Allan Pringle, William Joseph James, Y. Kong

Physics Faculty Research & Creative Works

Structures and magnetic properties of the LaNi_5-xFe_x and LaNi_5-xMn_x compounds have been investigated using neutron diffraction and first-principles tight-binding-linear-muffin-tin-orbital methods. Both neutron diffraction refinement data and total energy calculations show that the Fe and Mn atoms preferentially occupy the 3g sites in the hexagonal CaCu₅-type structure. The calculated magnetic moments of Fe and Ni atoms are of 2.4-2.5μ_B and 0.2-0.5μ_B in LaNi_5-xFe_x, respectively. The magnetic structure exhibits more localized moments at Fe atoms in LaNi_5-xFe_x when x ≤ 1.0. Electronic structure calculations indicate …

Enhancing Training And Presence In Virtual Environments Using Passive Haptics, Brent E. Insko

Link Foundation Modeling, Simulation and Training Fellowship Reports

One of the worst virtual environment experiences is to virtually contact something and feel nothing. Visual-haptic sensory conflicts are normally dominated by visual perception. Therefore, augmenting a high-fidelity visual virtual environment with low-fidelity haptic objects, called passive haptics, should markedly improve both sense of presence and task training effectiveness. Testing these hypotheses, I found adding a 1.5 inch physical ledge to a visual-cliff virtual environment increased participants' sense of presence as measured by subjective questionnaires, observed participant behaviors, and physiological responses. I next examined memory model creation and training effectiveness for a navigation task in a virtual environment with and …

Computer Graphics Optique: Optical Superposition Of Projected Computer Graphics, Aditi Majumder

Link Foundation Modeling, Simulation and Training Fellowship Reports

We present some ideas and demonstrations for a hybrid projector-based rendering and display technique we call Computer Graphics Optique. Instead of partially overlapping projected images to achieve a wide-area display, we completely overlap projected images on top of each other to achieve the addition of light and color in an "optical composition buffer''. The idea is to use the optical composition to replace some analytical computation, to increase rendering speed, gain flexibility, intensity range, and intensity resolution. Where projector-based displays are appropriate, potential uses include the optical realization of certain effects normally requiring a digital accumulation buffer, the optical composition …

Computer Graphics Optique: Optical Superposition Of Projected Computer Graphics, Aditi Majumder

Link Foundation Modeling, Simulation and Training Fellowship Reports

We present some ideas and demonstrations for a hybrid projector-based rendering and display technique we call Computer Graphics Optique. Instead of partially overlapping projected images to achieve a wide-area display, we completely overlap projected images on top of each other to achieve the addition of light and color in an "optical composition buffer''. The idea is to use the optical composition to replace some analytical computation, to increase rendering speed, gain flexibility, intensity range, and intensity resolution. Where projector-based displays are appropriate, potential uses include the optical realization of certain effects normally requiring a digital accumulation buffer, the optical composition …

Potential Nrm Structures For Western Australia, Department Of Agriculture And Food, Western Australia

All other publications

A discussion paper to scope and present options for regional Natural Resources Management (NRM) structures suited to Western Australia’s South West agricultural division.

The Functionalization Of Thermally Stable Third-Order Nlo Chromophores, James Richard Sawyer

Browse all Theses and Dissertations

There is a need to functionalize NLO chromophore systems to incorporate them into polymeric matricies by covalent attachment. The functionalization of a series of NLO chromophores based on the N,N-diphenyl-N-[7-(2-benzothiazolyl)-9,9-diethyl-2- fluorenyl ]amine structure has been investigated. All the chromophores were synthesized from the intermediate chromophore N-phenyl-N-[4-(4-bromophenyl)phenyl ]-N-[7-(2- benzothiazolyl)-9,9-diethyl-2-fluorenyl ]amine which was prepared by a six-step process. Bromination of fluorene yielded 2,7-dibromo-fluorene which could be converted to 2,7- dibromo-9,9-diethylfluorene by alkylation with ethyl iodide in DMSO.Reaction of 2,7- dibromo-9,9-diethylfluorene with one equivalent of butyl lithium followed by reaction with DMF provides 2-bromo-7-formyl-9,9-diethylfluorene.Condensation of 2-bromo-7- formyl-9,9-diethylfluorene and 2-aminobenzenethiol in DMSO results in …

Sedimentary Cyclicity In Crp Drillcore, Victoria Land Basin, Antarctica, T. R. Naish, P. J. Barrett, G. B. Dunbar, K. J. Woolfe, A. G. Dunn, S. A. Henrys, M. Claps, R. D. Powell, Christopher R. Fielding

Department of Earth and Atmospheric Sciences: Faculty Publications

The upper 1200 m of pre-Pliocene sediment recovered by Cape Roberts Project (CRP) drilling off the Victoria Land coast of Antarctica between 1997-1999 has been subdivided into 54 unconformity-bound stratigraphic sequences, spanning the period c. 32 to 17 Ma. The sequences are recognised on the basis of the cyclical vertical stacking of their constituent lithofacies, which are enclosed by erosion surfaces produced during the grounding of the advancing ice margin onto the sea floor. Each sequence represents deposition in a range of offshore shelf to coastal glacimarine sedimentary environments during oscillations in the ice margin across the Western Ross Sea …

Building Blocks For Reliable Complex Nonlinear Numerical Simulations, Helen Yee

United States National Aeronautics and Space Administration: Publications

This chapter describes some of the building blocks to ensure a higher level of confidence in the predictability and reliability (PAR) of numerical simulation of multiscale complex nonlinear problems. The focus is on relating PAR of numerical simulations with complex nonlinear phenomena of numerics. To isolate sources of numerical uncertainties, the possible discrepancy between the chosen partial differential equation (PDE) model and the real physics and/or experimental data is set aside. The discussion is restricted to how well numerical schemes can mimic the solution behavior of the underlying PDE model for finite time steps and grid spacings. The situation is …

Entropy Splitting For High Order Numerical Simulation Of Vortex Sound At Low Mach Numbers, B. Müller, H.C. Yee

United States National Aeronautics and Space Administration: Publications

A method of minimizing numerical errors, and improving nonlinear stability and accuracy associated with low Mach number computational aeroacoustics (CAA) is proposed. The method consists of two levels.

Evolving Tenure Rights And Agricultural Intensification In Southwestern Burkina Faso, Michael Kevane, Leslie C. Gray

Economics

Popular and official representations of the environment in Burkina Faso present soils as fragile and potentially subject to catastrophic collapse in fertility. In the cotton growing zone of southwestern Burkina Faso, researchers and policy makers attribute changes in land cover and land quality to population growth. This paper presents evidence questioning the dominant "population-degradation narrative" as applied to Burkina. We find that farmers are intensifying their production systems. While population has led to land scarcity, farmers are responding to both the resulting uncertainty in land rights and reductions in soil quality by intensifying the production process. Investments are used both …

Soilguide (Soil Guide) : A Handbook For Understanding And Managing Agricultural Soils, Geoff Allan Moore

Bulletins 4000 -

This handbook integrates the current knowledge of soils in south-western Australia in a user-friendly form. It describes how to assess which soil properties influence production and land degradation in the agricultural area and summarises management options to remedy or minimise soil limitations. The potential for growing a large range of crops and pastures can be assessed. In particular, the links between soil morphology, soil properties, management and agronomy are emphasised. The manual is designed for use at the paddock scale or for site assessment, but it can also be used at a catchment or regional scale. It is specifically designed …

South West Hydrological Information Package : Understanding And Managing Hydrological Issues On Agricultural Land In The South West Of Western Australia, Peter J. Tille, T W. Mathwin, Richard J. George Dr

Bulletins 4000 -

This manual reviews current knowledge of the hydrological issues that affect, or are affected by, agriculture in the catchments of the south west of Western Australia.

Wa Soil Erosion Under Investigation, George Richard Dr

Journal of the Department of Agriculture, Western Australia, Series 4

A survey of soil erosion at 70 sites throughout Western Australia, recently completed as a part of a National Reconnaissance Survey, has shown that erosion is occurring at an unsustainable rate. While still to be compiled into a national publication, Dr Richard George reports on the Western Australian results, and discusses options for management and further investigation.

Relationship Between Durophagy And Feeding Biomechanics In Gray Triggerfish, Balistes Capriscus: Intraspecific Variation In Ecological Morphology, Christopher J. Durie, Ralph G. Turingan

Ocean Engineering and Marine Sciences Faculty Publications

The relationship between oral jaw biomechanics and consumption of hard prey was compared between Gulf of Mexico (Gulf) and Atlantic Ocean (Atlantic) populations of gray triggerfish (Balistes capriscus) to examine intraspecific ecomorphological variation between these fish. Gut content analysis revealed that Atlantic fish fed more on hard-shelled invertebrates, such as crabs and sea urchins, than Gulf conspecifics. Difference in the relative magnitude of durophagy between Gulf and Atlantic triggerfish was associated with intraspecific differences in key biomechanical properties of the prey-capture and processing mechanism. The more durophagous Atlantic B. capriscus had more massive jaw bones and muscles than Gulf fish. …

Department Of Fisheries Annual Report To Parliament 2000 - 2001, Department Of Fisheries, Western Australia

Department of Fisheries Annual Reports

In accordance with Section 62 of the Financial Administration and audit Act 1985 and Section 263 of the Fish Resources Management Act 1994, I submit for your information the Annual report to Parliament of Fisheries WA for the financial year ending 30 June 2001.

The annual report has been prepared in accordance with the provisions of the Financial Administration and audit Act 1985 and Section 263 of the Fish Resources Management Act 1994.

2000/2001 was a year for Fisheries WA marked by the challenges of managing change. The year saw a change of government and, as with all new governments, …

The Lattice Dynamics And The Elastic Behaviour Of Fcc And Bcc Ba, Yasemi̇n Özteki̇n Çi̇ftçi̇, Kemal Çolakoğlu

Turkish Journal of Physics

The two-body pairwise E.G.E.P. (Extended Generalized Exponantial Potential) type Morse potential and volume dependent energy are assumed to represent the total energy of the Ba crystal. The parametrized potential is used to calculate the second- and third-order elastic constants C_{ij} and C_{ijk}, pressure derivatives of bulk moduli and Grüneisen parameter \gamma . The phonon frequencies are also computed and plotted. The obtained results are compared with available experimental data and, in general, the agreement is good.

Computational Study For The Structural Change Of The System Cdte_{1-X} S_X Thin Film, Emad Khdayer Al-Shakarchi

Turkish Journal of Physics

Polycrystalline thin film of the graded system CdTe_{1-x}S_{x} for x=0,0.1,\ldots,1 are prepared by using thermal evaporation technique deposited on the glass substrate with an average thickness 3000 Å for each individual value of x . XRD technique is used with the aid of a computational program to study the phase change from cubic zinc blend structure to hexagonal wurtzite with an inversion point related to the x-value. It is found that x=0.1 gives us an inversion point in the structural change from cubic to hexagonal phase.

A Theoretical Model For The Non-Linear Susceptibility Of The Antiferromagnetic Systems, Beki̇r Özçeli̇k, Keri̇m Kiymaç, Ahmet Eki̇ci̇bi̇l

Turkish Journal of Physics

In this study, we have developed a general theoretical model, based upon the simple mean field model of N\'{e}el, for the non-linear response of an antiferromagnetic system. The results indicate that the odd order derivatives, (d^{2n + 1}m_{a})_{0} = (-d^{2n + 1}m_{b})_{0}, where n=1,2,3......, will diverge and the even order derivatives, (d^{2n}m_{a})_{0} = (d^{2n}m_{b})_{0} will vanish due to the symmetry of two sublattices, ``a'' and ``b'', forming the antiferromagnet. This model also supports our experimental results performed on two antiferromagnetic samples, namely, Cs_{2}MnCl_{4}.2H_{2}O and MnCl_{2}.4H_{2}O [1].

Iba-1 Calculations Of E2/M1 Mixing Ratios And Quadrupole Moments In ^{154}Gd, Mehmet Baylan

Turkish Journal of Physics

In this study the Interacting Boson Approximation is applied in its basic form (IBA-1) to the calculation of gamma-ray E2/M1 multipole mixing ratios and quadrupole moments [Q( 2^{+} )] of electromagnetic transitions in ^{154}Gd. The numerical results obtained for ^{154}Gd are in reasanably good agreement with previous experimental and theoretical values.

Excitation Plus Ionization In Electron-Atom Collisions To He^{+} (N=2): (E,2e), (E, E\Gamma ) And (E, 2e\Gamma ) Studies, Mevlut Dogan, Albert Crowe

Turkish Journal of Physics

Simultaneous excitation-ionization of helium atoms by electron impact is observed by the coincidence detection of the outgoing particles. The relationship between (e,2e), (e,e\gamma ) and (e,2e\gamma ) experiments is discussed.

Covariant Two Fermion Equations With Anomalous Moments, Ahmet Turan Alan, Z. Zekeri̇ya Aydin, Nuretti̇n Karagöz, Ali̇ Ulvi̇ Yilmazer

Turkish Journal of Physics

We derive covariant equations for two-fermion systems, taking into account the anomalous magnetic moments of the particles.

Double Transition Effect In Anderson Transition, Hüseyi̇n Aktaş

Turkish Journal of Physics

In this work we have studied the electronic mobility \mu within a completely disordered lattice system by using the strong interatomic hopping potential V(r) = ( - {\frac{{r}}{{a_{o}} }}) \exp( - r / a_{o} ) for site representation of the Hamiltonian. It is shown that a metallic system of a completely disordered lattice first goes insulating and then goes back to metallic again at higher atomic density \rho .

Autoionization Resonances In The Simultaneous Excitation-Ionization Of Helium, Mevlut Dogan, Albert Crowe

Turkish Journal of Physics

The effect of autoionizing states on excitation-ionization processes has been investigated experimentally by observation of the electron impact ionization process leading to He^{ + }(2p) with the excitation energy region in helium corresponding to doubly excitated states above the second ionization threshold. Also, the process arising from the decay of the doubly excited `parity unfavoured' (2p^{2})^{3}P state of helium, is studied.