Physical Sciences and Mathematics Commons^™

Network Security: An Evaluation Of Security Policies And Firewall Implementations, Melanie L. Abbas

Dissertations and Theses @ UNI

This paper begins focusing on network security issues. The areas of physical security, access security, and connection security are explored. Connection security provides the biggest need for improvement in the entire security field. This type of security is managed best with firewall implementations. Various firewall models are discussed.

Software evaluations were performed on three different commercial Internet security tools. The software was compared on the basis of ease of installation, functionality, level of security provided, and output available. In summary, the value of the firewall is dependent on the need to implement a firewall in an organization.

However, a security …

Search And Tracking Algorithms For Rapidly Moving Mobiles, Amy L. Murphy, Gruia-Catalin Roman, George Varghese

All Computer Science and Engineering Research

With the advent of wireless technology and laptops, mobility is an important area of research. A fundamental problem in this area is the delivery of messages to a moving mobile. Current solutions work correctly only for slowly moving nodes that stay in one location long enough for tracking to stabilize. In this paper we consider the problem of message delivery to rapidly moving mobile units. With these algorithms, we introduce a new method for designing algorithms based on the paradigm of considering a mobile unit as a message, and adapting traditional message passing algorithms to mobility. Our first algorithm is …

Leafy Spurge (Euphorbia Esula L.) Spread In Iowa, S. C. Huerd, S. E. Taylor

Journal of the Iowa Academy of Science: JIAS

Leafy spurge (Euphorbia esula L.), a noxious perennial weed spreading south from the northern Great Plains into Iowa, is considered a threat to Iowa's Prairie preserves because it is an aggressive non-native plant that dominates the landscape through rapid sexual and asexual reproduction. Methods to control leafy spurge include cultural and chemical controls, and biological controls are currently being developed. In 1992 and 1993 we surveyed the extent of leafy spurge spread in Iowa and found 26 of 99 Iowa counties with leafy spurge populations. Iowa's leafy spurge populations are rapidly expanding on untilled lands such as roadsides, especially in …

Book Review - Birds In Iowa, Peter Wickham

Journal of the Iowa Academy of Science: JIAS

Here is a book that those who are interested in birds and their distribution in Iowa will absolutely have to possess. This volume is the successor to the book Iowa Birds, which was written by the above authors together with three others and published in 1984. It brings our understanding to the number of species of birds and their relative abundance in Iowa up-to-date. Although only twelve years elapsed between the publication of the previous volume and this one, the activity of those interested in identifying birds increased enormously during those years. In addition, their ability to identify and find …

Status Of Aquatic Vascular Plants 1n Iowa's Natural Lakes, G. S. Phillips

Journal of the Iowa Academy of Science: JIAS

Conversion of wetlands to agricultural land during the settlement of Iowa has resulted in a significant decline in the total area of lake habitat in the state. This reduction in area, combined with the degradation of remaining sites, resulted in dramatic reductions in aquatic vascular plant populations associated with Iowa's natural lakes. While declines in plant species inhabiting fen, bog, seepage, prairie pothole, and marsh type wetlands have been extensively documented, few quantitative data exist for lake type wetlands. During the summer of 1996, a total of 86 natural lakes in Iowa were surveyed for aquatic vascular plants. Many of …

Iowa's Odonata: Declining And/Or Changing?, Robert W. Cruden, O. J. Gode Jr.

Journal of the Iowa Academy of Science: JIAS

We undertook a comprehensive survey of the Order Odonata in Iowa. Because the credibility of our conclusions derives from our collecting strategy and effort, we discuss our strategy in depth. We collected throughout the state (more than 500 sites in 94 counties), throughout the flight season (late May-early October), and tried to visit several habitats in each county. Our 7900+ observations made between 1993 and 1996 include approximately 2300 county records, 93 of the 110 species reported for the state, and eight species previously unknown from the state. At least 30 species are secure and occur across the state. Other …

Optical Digital Fragmentation Measuring Systems -- Inherent Sources Of Error, Norbert H. Maerz, Wei Zhou

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Automated optical imaging systems of measuring fragmentation are increasingly being used in the mining, comminution, and materials handling industries. These methods have been well received in many of the industries involved. Considering that in many of these applications there are no alternative ways of sizing material, having even a rudimentary measurement of size distributions allows evaluations of explosive, blast design, detonator performance, crusher and milling performance, and material degradation due to transport.

Optical methods have inherent limitations, which reflect on accuracy, precision, and reproducibility of measurement results. This stems from the fact that there are myriads of variables, which affect …

Quadratic Convergence Of Approximate Solutions Of Two-Point Boundary Value Problems With Impulse, Vidya Doddaballapur, Paul W. Eloe, Yongzhi Zhang

Mathematics Faculty Publications

The method of quasilinearization, coupled with the method of upper and lower solutions, is applied to a boundary value problem for an ordinary differential equation with impulse that has a unique solution. The method generates sequences of approximate solutions which converge monotonically and quadratically to the unique solution. In this work, we allow nonlinear terms with respect to velocity; in particular, Nagumo conditions are employed.

Cell Size Dependence Of Transport Coefficients In Stochastic Particle Algorithms, Alejandro Garcia, F. Alexander, B. Alder

Alejandro Garcia

Using the Green–Kubo theory, the dependence of the viscosity and thermal conductivity on cell size is obtained explicitly for stochastic particle methods such as direct simulation Monte Carlo (DSMC) and its generalization, the consistent Boltzmann algorithm (CBA). These analytical results confirm empirical observations that significant errors occur when the cell dimensions are larger than a mean free path.

Twisting Of X-Ray Isophotes In Triaxial Galaxies, Aaron J. Romanowsky, C. S. Kochanek

Aaron J. Romanowsky

We investigate X-ray isophote twists created by triaxiality differences between the luminous stellar distributions and the dark halos in elliptical galaxies. For a typically oblate luminous galaxy embedded in a more prolate halo formed by dissipationless collapse, the triaxiality difference of ΔT simeq 0.7 leads to typical isophote twists of langΔψXrang simeq 16° ± 19° at 3 effective stellar radii. In a model that includes baryonic dissipation, the effect is smaller, with ΔT simeq 0.3 and langΔψXrang simeq 5° ± 8°. Thus, accurate measurements of X-ray isophote twists may be able to set constraints on the interactions between baryons and …

Radicals, Metals And Magnetism, David J R Brook

David J. R. Brook

The interaction between unpaired electrons governs many physical properties of materials. Although in a fundamental sense the interaction is simple, a full understanding of the interaction in molecular systems is complicated by the presence of other bonding and non-bonding electrons. The resulting many body problem is very challenging. Nevertheless, much qualitative understanding can be obtained from applying simple molecular orbital theory and considering only the partly filled orbitals. The resulting model can be used to describe existing diradical and metal-radical systems and also has predicative value in the search for molecular magnets and design of nanoscale devices.

On The (10, 5, Λ)-Family Of Bhaskar Rao Designs, G. Chaudhry, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We prove a theorem for BRD(10,5,Lambda)s and give thirteen (13) inequivalent BRD(10,5,4)s.

Perfect Secret Sharing Schemes From Room Squares, G. R. Chaudhry, H Ghodosi, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

Secret sharing schemes are one of the most important primitives in distributed systems. In perfect secret sharing schemes, collaboration between unauthorised participants cannot reduce their uncertainty about the secret. This paper presents a perfect secret sharing scheme arising from critical sets of Room squares.

On New Families Of Supplementary Difference Sets Over Rings With Short Orbits, M. Gysin, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We discuss difference sets (DS) and supplementary difference sets (SDS) over rings. We survey some constructions of SDS over Galois rings where there are no short orbits. ,From there we move to constructions which involve short orbits. These give rise to new infinite families of SDS over GF(p) x GF(q), p, q both prime powers. Many of these families have λ = 1. We also show some new balanced incomplete block designs and pairwise balanced designs arising from the constructions given here.

Necessary And Sufficient Conditions For Some Two Variable Orthogonal Designs In Order 44, C. Koukouvinos, M. Mitrouli, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We give a new algorithm which allows us to construct new sets of sequences with entries from the commuting variables 0, ± a, ± b, ± c, ± d with zero autocorrelation function. We show that for twelve cases if the designs exist they cannot be constracted using four circulant matrices in the Goethals-Seidel array. Further we show that the necessary conditions for the existence of an OD(44; s1, s2) are sufficient except possibly for the following 7 cases: (7, 32) (8, 31), (9, 30) (9, 33) (11,30) (13, 29) (15, 26) which could not be found because of the …

Larval Black Crappie Distribution: Implications For Sampling Impoundments And Natural Lakes, Kevin L. Pope, David W. Willis

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

An understanding of larval fish distributions is essential for developing an appropriate sampling design to monitor larval abundances. We monitored abundance of larval black crappie Pomoxis nigromaculatus to assess spatial differences in Richmond Lake (a 336-ha impoundment) and Brant Lake (a 405-ha natural lake), South Dakota, during 1994–1996. Age-0 black crappies were collected with a 500-µm mesh ichthyoplankton trawl from fixed sites within each water body. In the impoundment, larval black crappies were collected over a longer period at the upper site than at the dam site during 1994 and 1995. In the natural lake, larval black crappie abundances were …

Earlj Life Historj And Recruitment Of Black Crappie (Pomoxis Nigromaculatus) In Two South Dakota Waters, K. L. Pope, D. W. Willis

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

We compared the early life history of black crappie (Pomoxis nigromaculatus) in Richmond (an impoundment) and Brant (a natural lake) lakes during 1994-1996. We expected variable recruitment (i.e., missing year classes) in the natural lake and more consistent recruitment in the impoundment. Larval black crappie abundance was always higher in Richmond Lake than Brant Lake. Peak abundance of larval black crappie was highest during 1994 in both waters. However, peak larval abundance did not correspond with fall trap-net catch per unit effort (CPUE) of age-0 black crappie, which was highest during 1995. Thus, recruitment of black crappie was …

Drought-Induced Shift Of A Forest–Woodland Ecotone: Rapid Landscape Response To Climate Variation, Craig Allen, David D. Breshears

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

In coming decades, global climate changes are expected to produce large shifts in vegetation distributions at unprecedented rates. These shifts are expected to be most rapid and extreme at ecotones, the boundaries between ecosystems, particularly those in semiarid landscapes. However, current models do not adequately provide for such rapid effects—particularly those caused by mortality—largely because of the lack of data from field studies. Here we report the most rapid landscape-scale shift of a woody ecotone ever documented: in northern New Mexico in the 1950s, the ecotone between semiarid ponderosa pine forest and pinon– juniper woodland shifted extensively (2 km or …

Generalized Multiphoton-Ionization Cross Sections Of The Rare Gases For 500-Fs, 248.6-Nm Pulses, Cornelis J. Uiterwaal, D. Xenakis, D. Charalambidis, P. Maragakis, H. Schröder, P. Lambropoulus

C.J.G.J. Uiterwaal Publications

Absolute values for the generalized multiphoton-ionization cross sections and saturation intensities of rare gases are reported for 500-fs, 248.6-nm pulses. For He, Ar, and Kr these values are experimentally determined from the intensity dependence of the ponderomotive shift for intensities comparable to and above the saturation intensity. The measured experimental cross sections [σ₍₅₎^He=(0.9₊₉^-o.4)×10^-152 cm¹⁰ s⁴, σ₍₄₎^Ar=(1.3₊₁^-0.5)×10^-116 cm⁸ s³, σ₍₅₎^Kr=(1.2_+1.7^-0.6)×10^-82 cm⁶ s², σ₍₃₎^Xe=(50_-45⁺³⁵⁰)×10^-82 cm …

Isotope Geochemistry Of Proterozoic Talc Occurrences In Archean Marbles Of The Ruby Mountains, Southwest Montana, U.S.A, John B. Brady, John T. Cheney, Amy Larson Rhodes, Angela Vasquez, Chris Green, Mathieu Duvall, Ari Kogut, Lewis Kaufman, Dana Kovaric

Geosciences: Faculty Publications

Talc occurs as massive, economic deposits in upper amphibolite facies marbles of Archean age in southwestern Montana. Previous workers have demonstrated that the talc is a replacement of the marble that resulted from interaction with a large volume of fluid. δ18O (SMOW) values for dolomite and calcite range from 20-25‰ for the unaltered Archean marbles to as little as 8-10‰ in the talc deposits, suggesting that the metasomatic fluids had low δ18O values. In contrast, δ13C values for calcite and dolomite are similar for all samples (-2 to +2‰ PDB). Therefore, it is likely that the metasomatic fluids were oxygen-rich …

Dimensionality And Energy Levels Of Quantum Mechanical Systems, Harry A. Mavromatis

Turkish Journal of Physics

The $N$-dimensional Schrödinger equation involving a general, central potential $V_N(r)$, is decomposed into a 3-dimensional component plus a term that may be treated as a dimension-dependent perturbation. This allows discussion of the general $N$-dimensional system from a 3-dimensional perspective.

Structural Defects And Electrical Properties Of Extruded Samples Of Bi_{85}Sb_{15} Solid Solutions, Farkhad Samedov, Mail Tagiev

Turkish Journal of Physics

The effect of 5 hours annealing in vacuum $\sim 10^{-3} Pa$ at $503 K$ on the electroconductivity $(\sigma)$, the coefficient of thermoelectric power $(\alpha)$ and the Hall coefficient $(R_x)$ for extruded samples of $Bi_{85}Sb_{15}$ has been investigated in the temperature range from $\sim 77 K$ up to $\sim 300 K$. The samples were taken with a different concentration of $Pb$ (lead) up to $\sim 0.1 a.w \%$. The anisotropy of electrical properties of these samples was also studied in the temperature range between $77 K$ and $300 K$ and in the presence of magnetic field up to $\sim 74 \times …

Theoretical Analysis Of The Crystallography For Do_3 --> M18r Martensitic Transformation, Seyfettin Çakmak, Ekrem Artunç

Turkish Journal of Physics

A mathematical approach of the phenomenological theory has been applied to the martensitic transformation of DO$_3 \rightarrow$ M18R close-packed structure. The crystallography of DO$_3 \rightarrow$ M18R martensitic transformation in Fe-25.8 wt\%Mn-7.4wt\%Al-0.11wt\%C alloy was studied using single crystals. Martensitic crystallographic parameters such as habit plane, magnitude of lattice invariant shear, shape deformation direction and orientation relationships are calculated with new mathematical approach. Phenomenological theoretical calculations were compared with predictions of the phenomenological crystallographic CRAB theory and with experimental observations.

Effect Of Neutron Irradiation On Carriers Removel Rates In N-Si, M.S. Yunusov, M. Karimov, B.L. Oksengendler, M.A. Zhalelov

Turkish Journal of Physics

Carrier removal rate in $n-Si \langle P, Rh \rangle$ with different doping rhodium concentrations were investigated under fast neutrons irradiation. It is shown that the rate of carrier removal increases with phosphorus atom concentration but decreases with rhodium atom concentration. Theoretical analysis on the base of kinetic equations has shown that standard scheme of quasichemical reactions taking into account the interaction between rhodium atoms, vacancies and self interstitial atoms could not explain the results of experiment. Therefore a new model based on the use of radiation to increase the barrier between regions of fluctuating impurity concentration has been proposed.

An Analysis Of The Variation In Calculated Confined-State Energies Using Different Envelope-Function Models, Beşire Gönül

Turkish Journal of Physics

We investigate different formulations of the envelope-function method and show that the accuracy of the calculated zone-centre confinement energies can be calculated by means of bulk band structure. We show how coupling to the conduction and spin-split-off bands can decrease the light-hole zone-centre confinement energies and lead to significant differences in the calculated subband dispersion.

Fibonaccization And Multiparameter Q-Oscillator, M. Arik, T. Rador, G. Ünel

Turkish Journal of Physics

Starting from Coon-Baker-Yu (CBY) q-oscillator, a two parameter, multidimensional q-oscillator is formulated. It is shown that this procedure, called Fibonaccization, can be extended to any number of parameters. The relation between CBY states and Fibonacci CBY states are also investigated.

Comparison Of Metallicities Adopted For The Synthetic Ubv Photometry With Those Evaluated By Means Of Rgu Photometry, S. Karaali̇, S. Güngör, Y. Karataş

Turkish Journal of Physics

Comparison of metallicities adopted for synthetic UBV photometry with those evaluated by means of RGU photometry for 92 stars is presented. The agreement is only for zero metallicity. The discrepancy increases to low metallicities which cover Intermediate Population II and Population II main-sequence stars. U-G and G-R colour indices are transformed from UBV synthetic data and do not include any observational error. Therefore, the disagreement may originate from a systematic error in the metallicity calibration of relatively metal-poor stars in RGU photometry. Keywords: photometry - stars : abundances - metal-poor.

Magnetic Diffuse Scattering In The Frustrated Square Lattice, Ali Bayri, Funda Ersoy Atalay, Hüseyin Gencer

Turkish Journal of Physics

Some of the first transition metal alloys show first order antiferromagnetic phase transition as a function of alloy concentration [1-5]. The antiferromagnetism of materials can be classified into three different class: type I, type II and type III. Although the neutron diffraction studies give information about the type of magnetism, they do not show the fluctuations of magnetic moment from the original direction. So in order to have some information about this fluctuations one must perform the magnetic diffuse scattering. Recently, we proposed that the square lattice may have a double-Q structure as well as single-Q [6]. We showed that …

Solution Of Optic Reconstructive Problem Considering Registered Signal Velocity, A.A. Aliverdiev, M.G. Karimov

Turkish Journal of Physics

A solution to the tomographic problem of dynamic reconstruction of a processes, the rate of which is comparable with the velocity of the registered signal is presented. The obtained data can be used both for theoretical and applied tomography.

Resonans Reflectionless Absorption Ofelectromagnetic Waves In Solutions, E. Salaev, E. Gasimov, S. Azizov, J. Qajar

Turkish Journal of Physics

No abstract provided.