Physical Sciences and Mathematics Commons^™

Risk Regulation And The Faces Of Uncertainty, Vern R. Walker

RISK: Health, Safety & Environment (1990-2002)

Dr. Walker addresses the difficulty of regulators' working with potentially inaccurate information and clarifies related aspects of decision making by presenting a taxonomy for the kinds of uncertainty inherent in necessarily incomplete data.

Monte Carlo Simulation In Environmental Risk Assessment--Science, Policy And Legal Issues, Susan R. Poulter

RISK: Health, Safety & Environment (1990-2002)

Dr. Poulter notes that agencies should anticipate judicial requirements for justification of Monte Carlo simulations and, meanwhile, should consider, e.g., whether their use will make risk assessment policy choices more opaque or apparent.

Pigford, Shrader-Frechette & The Nrc Report On Yucca Mountain: Comment, David Okrent

RISK: Health, Safety & Environment (1990-2002)

Dr. Okrent raises several questions related to, e.g., the uneven application of the goal of intergenerational equity.

Table Of Contents Volume Nine, Number One, Winter 1998, Risk Editorial Board

RISK: Health, Safety & Environment (1990-2002)

Table of contents for the journal RISK: Health, Safety & Environment (ISSN: 1073-8673)

A Method Of Identifying Hazardous Highway Locations Using The Principle Of Individual Lifetime Risk, Paul J. Ossenbruggen

RISK: Health, Safety & Environment (1990-2002)

Dr. Ossenbruggen presents a scientific framework for identifying hazardous highway locations that may be more easily understood by non-scientists and has potential for comparing highway with other risks to health.

Cusp Energetic Particle Events: Implications For A Major Acceleration Region Of The Magnetosphere, J. Chen, T. A. Fritz, R. B. Sheldon, Harlan E. Spence, W. N. Spjeldvik, J. F. Fennell, S. Livi, C. T. Russell, J. S. Pickett, D. A. Gurnett

Physics & Astronomy

The Charge and Mass Magnetospheric Ion Composition Experiment (CAMMICE) on board the Polar spacecraft observed 75 energetic particle events in 1996 while the satellite was at apogee. All of these events were associated with a decrease in the magnitude of the local magnetic field measured by the Magnetic Field Experiment (MFE) on Polar. These new events showed several unusual features: (1) They were detected in the dayside polar cusp near the apogee of Polar with about 79% of the total events in the afternoonside and 21% in the morningside; (2) an individual event could last for hours; (3) the measured …

The Pursuit Of Isotopic And Molecular Fire Tracers In The Polar Atmosphere And Cryosphere, L A. Currie, Jack E. Dibb, G A. Klouda, B A. Benner Jr., J M. Conny, S R. Biegalski, D B. Klinedinst, D R. Cahoon, N C. Hsu

Earth Sciences

We present an overview of recent multidisciplinary, multi-institutional efforts to identify and date major sources of combustion aerosol in the current and paleoatmospheres. The work was stimulated, in part, by an atmospheric particle 'sample of opportunity' collected at Summit, Greenland in August 1994, that bore the 14C imprint of biomass burning. During the summer field seasons of 1995 and 1996, we collected air filter, surface snow and snowpit samples to investigate chemical and isotopic evidence of combustion particles that had been transported from distant fires. Among the chemical tracers employed for source identification are organic acids, potassium and ammonium ions, …

Mev Measurements Of Gamma-Ray Bursts By Cgro-Comptel, A Connors, W Collmar, W Hermsen, S C. Kappadath, R M. Kippen, L Kuiper, Mark L. Mcconnell, F Pelaez, James M. Ryan, V Schonfelder, M Varendorff, O R. Williams, C Winkler, C A. Young

Space Science Center

Since the launch of the Compton Gamma-Ray Observatory in April 1991, the imaging COMPTEL telescope has accumulated positions and 0.75–30 MeV spectra of more than thirty gamma-ray bursts within its ∼π sr field of view. In an ongoing collaboration with BACODINE/GCN, COMPTEL positions are relayed to a global network of multiwavelength observers in near real time (∼10 minutes). Here we summarize the MeV properties, and present spatial, spectral, and temporal data for the latest of these events, GRB 970807. In concurrence with earlier SMM and current BATSE, OSSE, and EGRET measurements, COMPTEL data add to the accumulating evidence that GRB …

Sontrac—A Low Background, Large Area Solar Neutron Spectrometer, James M. Ryan, D Holslin, John R. Macri, Mark L. Mcconnell, Cornelia B. Wunderer

Space Science Center

SONTRAC is a scintillating fiber neutron detector designed to measure solar flare neutrons from a balloon or spacecraft platform. The instrument is comprised of alternating orthogonal planes of scintillator fibers viewed by photomultiplier tubes and image intensifier/CCD camera optics. It operates by tracking the paths of recoil protons from the double scatter of 20 to 200 MeV neutrons off hydrogen in the plastic scintillator, thereby providing the necessary information to determine the incident neutron direction and energy. SONTRAC is also capable of detecting and measuring high-energy gamma rays >20 MeV as a “solid-state spark chamber.” The self-triggering and track imaging …

A Hard X-Ray Solar Flare Polarimeter Design Based On Scintillating Fibers, James M. Ryan, Mark L. Mcconnell, D J. Forrest, John R. Macri, M Mcclish, W T. Vestrand

Space Science Center

We have developed a design for a Compton scatter polarimeter to measure the polarization of hard X-rays (50–300 keV) from solar flares. The modular design is based on an annular array of scintillating fibers coupled to a 5-inch position-sensitive PMT. Incident photons scatter from the fiber array into a small array of NaI detectors located at the center of the annulus. The location of the interactions in both the fiber array and in the NaI array can be used to measure the linear polarization of the incident flux. This compact design may be well-suited to a variety of astrophysical applications. …

Mach-Zehnder Interferometer Fringe Projector For Variable Resolution Video Moire, Phillip C. Kalmanson, August Schutte, Chris L. Hart, Joel H. Blatt

Aerospace, Physics, and Space Science Faculty Publications

A Mach-Zehnder based variable resolution fringe projection system has been built for 3-D video moini machine vision. This system uses the three main advantages of the Mach-Zehnder - 1) There is no optical feedback to the laser source, 2) The interfemmeter can accept two different laser wavelengths simultaneously, and 3) The interferometer produces two orthngonal output beams. The lack of optical feedback makes the Mach-Zehnder especially attractive for use with high power laser diode sources which are sensitive to optical feedback. When the two input ports axe used with two different wavelength lasers, the target can be illuminated by simultaneous …

Steps Toward Determination Of The Size And Structure Of The Broad-Line Region In Active Galactic Nuclei. Xii. Ground-Based Monitoring Of 3c 390.3, Matthias Dietrich, T. D. Oswalt, Jun Tao

Aerospace, Physics, and Space Science Faculty Publications

Results of a ground-based optical monitoring campaign on 3C 390.3 in 1994-1995 are presented. The broadband fluxes (B, V, R, and I), the spectrophotometric optical continuum flux Fλ(5177 Å), and the integrated emission-line fluxes of Hα, Hβ, Hγ, He II λ15876, and He II A4686 all show a nearly monotonic increase with episodes of milder short-term variations superposed. The amplitude of the continuum variations increases with decreasing wavelength (4400-9000 Å). The optical continuum variations follow the variations in the ultraviolet and X-ray with time delays, measured from the centroids of the cross-correlation functions, typically around 5 days, but with uncertainties …

High-Altitude Polar Cap Electric Field Responses To Southward Turnings Of The Interplanetary Magnetic Field, Niescja E. Turner, D N. Baker, T I. Pulkkinen, H J. Singer, F Mozer, R P. Lepping

Physics and Astronomy Faculty Research

Interplanetary electric field coupling with the magnetosphere has been analyzed predominantly using data from the Wind magnetometer and the Polar electric field instrument. The coupling was investigated using the Polar Electric Field Instrument (EFI) to measure the electric field in the northern polar cap immediately following sharp southward turnings of the IMF as observed by Wind. Southward turnings were chosen which exhibited a sudden change of the IMF north-south component from B_Z > 0 to B^Z < 0 (GSM coordinates) after an hour or more of relatively stable conditions, and for which Polar was in the northern polar cap. These B_Z changes correspond to E_Y changes in the interplanetary electric field. For each of the 30 identified events, a time was estimated …

Magnetospheric Response Times Following Southward Imf Turnings, Niescja E. Turner, D N. Baker, T I. Pulkkinen, H J. Singer, F Mozer

Physics and Astronomy Faculty Research

We analyze the response times of various regions of the magnetosphere-ionosphere system to sudden southward turnings of the IMF. Our data set consists of 26 events during which the IMP B_Z component was observed by WIND to change from a stea northward field to a southward field, which subsequently led to a substorm. The magnetospheric response to such IMF southward turnings is examined using data from the POLAR EFI experiment, the GOES 9 magnetometer, and ground magnetometers. The POLAR/EFI was used to investigate changes in the polar cap electric field which occurred in response to the changing interplanetary electric …

Bayesian Hierarchical Analysis Of Minefield Data, Noel A. Cressie, Andrew B. Lawson

Faculty of Informatics - Papers (Archive)

Based on remote sensing of a potential minefield, point locations are identified, some of which may not be mines. The mines and mine-like objects are to be distinguished based on their point patterns, although it must be emphasized that all we see is the superposition of their locations. In this paper, we construct a hierarchical spatial point-process model that accounts for the different patterns of mines and mine-like objects and uses posterior analysis to distinguish between them. Our Bayesian approach is applied to COBRA image data obtained from the NSWC Coastal Systems Station, Dahlgren Division, Panama City, Florida. 2003 Copyright …

On The (10,5,$\Lambda$)-Family Of Bhaskar Rao Designs, Ghulam R. Chaundhry, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

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

An Experimental Search And New Combinatorial Designs Via A Generalisation Of Cyclotomy, Marc Gysin, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

Cyclotomy can be used to construct a variety of combinatorial designs, for example, supplementary difference sets, weighing matrices and T -matrices. These designs may be obtained by using linear combinations of the incidence matrices of the cyclotomic cosets. However, cyclotomy only works in the prime and prime power cases. We present a generalisation of cyclotomy and introduce generalised cosets. Combinatorial designs can now be obtained by a search through all linear combinations of the incidence matrices of the generalised cosets. We believe that this search method is new. The generalisation works for all cases and is not restricted to prime …

Bose's Method Of Differences Applied To Construct Bhaskar Rao Designs, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

In this paper we show that BIBD(v,b,r,k,λ) where v = pq or pq + 1, when written in the notation of Bose's method of differences may often be used to find generalized Bhaskar Rao designs GBRD(p,b',r',k,λ;G) where G is a group of order q and vice versa. This gives many new GBRDs including a GBRD(9,5,5;Z₅) and a GBRD(13,7,7;Z₇).

Infinite Families Of Generalized Bhaskar Rao Designs, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We show that GBRD(p,¹/₂(p-1), ¹/₈(p-1)(p-3);EA(¹/₂p-1)) exist for all prime powers p ≡ 3 (mod 4). We also show that GBRD(p,¹/₂(p - 1), ¹/₄(p - 1)(p - 3); EA(¹/₂(p - 1)) exist for all prime powers p ≡ 1 (mod 4).

This allows us to give a new proof that a BIBD(f(ef + 1),(ef + 1)(ef² + f -1),ef + f -1,f,f - 1) exists whenever p = ef + 1 is a prime power. This gives many …

Group Divisible Designs, Gbrdsds And Generalized Weighing Matrices, Dinesh G. Sarvate, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We give new constructions for regular group divisible designs, pairwise balanced designs, generalized Bhaskar Rao supplementary difference sets and generalized weighing matrices. In particular if p is a prime power and q divides p - 1 we show the following exist;

(i) GDD (2(p²+p+1), 2(p²+p+1), rp²,2p², λ1 = p²λ, λ2 = (p²-p)r, m=p²+p+1,n=2), r_+1,2;

(ii) GDD(q(p+1), q(p+1), p(q-1), p(q-1),λ1=(q-1)(q-2), λ₂=(p-1)(q-1)²/q,m=q,n=p+1);

(iii) PBD(21,10;K),K={3,6,7} and PDB(78,38;K), K={6,9,45};

(iv) GW(vk,k²;EA(k)) whenever a (v,k,λ)-difference set exists and k is a prime power;

(v) PBIBD(vk …

Numerical Algorithms For The Computation Of The Smith Normal Form Of Integral Matrices,, C. Koukouvinos, M. Mitrouli, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

Numerical algorithms for the computation of the Smith normal form of integral matrices are described. More specifically, the compound matrix method, methods based on elementary row or column operations and methods using modular or p-adic arithmetic are presented. A variety of examples and numerical results are given illustrating the execution of the algorithms.

Posets And Differential Graded Algebras, Jacqueline Ramagge, Wayne W. Wheeler

Faculty of Informatics - Papers (Archive)

If P is a partially ordered set and R is a commutative ring, then a certain differential graded /f-algebra A,(P) is defined from the order relation on P. The algebra A.(Vi) corresponding to the empty poset is always contained in A.(P) so that A,(P) can be regarded as an /4.(0)-algebra. The main result of this paper shows that if R is an integral domain and P and P' are finite posets such that A.(P) = A.(P') as differential graded /4,(0)-algebras, then P and P' are isomorphic. 1991 Mathematics subject classification (Amer. Math. Soc): primary 06A06.

A Haagerup Inequality For A1 X A1 And A2 Buildings, Jacqueline Ramagge, Guyan Robertson, Tim Steger

Faculty of Informatics - Papers (Archive)

Haagerup's inequality for convolvers on free groups may be interpreted as a result on A₁ buildings, i.e. trees. Here are proved analogous inequalities for discrete groups acting freely on the vertices of A₁ x A₁ and A₂ buildings. The results apply in particular to groups of typerotating automorphisms acting simply transitively on the vertices of such buildings. These results provide the first examples of higher rank groups with property (RD).

Image Compression Based On Genealogical Relation Of The Tsvq Indices, Jamshid Shanbehzadeh, Philip Ogunbona, Abdoihosein Sarafzadeh

Faculty of Informatics - Papers (Archive)

The indices obtained by tree-structured vector quantisation (TSVQ) have an interesting property that enables them to give information about the correlation between two image blocks. Iftwo image blocks are highly correlated, they may have an identical index, or the same ancestors. The existence of high inter-block correlation in natural images results in having neighboring blocks with the same genealogy. This characteristic can be used to compress the indices. This paper introduces a novel method to exploit the genealogical relation between the image block indices obtained from a TSVQ. The performance of this scheme in terms of PSNR versus average rate …

Covert Distributed Computing Using Java Through Web Spoofing, J. Horton, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We use the Web Spoofing attack reported by Cohen and also the Secure Internet Programming Group at Princeton University to give a new method of achieving covert distributed computing with Java. We show how Java applets that perform a distributed computation can be inserted into vulnerable Web pages. This has the added feature that users can rejoin a computation at some later date through bookmarks made while the pages previously viewed were spoofed. Few signs of anything unusual can be observed. Users need not knowingly revisit a particular Web page to be victims. We also propose a simple countermeasure against …

Bose's Method Of Differences Applied To Construct Bhaskar Rao Designs, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

In this paper we show that BIBD(v, b, r, k, λ), where v = pq or pq + 1, when written in the notation of Bose's method of differences may often be used to find generalized Bhaskar Rao designs GBRD(p, b', r', k, λ; G) where G is a group of order q and vice versa. This gives many new GBRDs including a GBRD(9, 5, 5; Z5) and a GBRD(13, 7, 7; Z7).

Equitable Key Escrow With Limited Time Span (Or, How To Enforce Time Expiration Cryptographically), M. Burmester, Y. Desmedt, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

With equitable key escrow the control of society over the individual and the control of the individual over society are shared fairly. In particular, the control is limited to specified time periods. We consider two applications: time controlled key escrow and time controlled auctions with closed bids. In the first the individual cannot be targeted outside the period authorized by the court. In the second the individual cannot withhold his closed bid beyond the bidding period. We propose two protocols, one for each application. We do not require the use of temper-proof devices.

The Translation Planes Of Order 49 And Their Automorphism Groups, C. Charnes, U. Dempwolff

Faculty of Informatics - Papers (Archive)

Using isomorphism invariants, we enumerate the translation planes of order 49 and determine their automorphism groups.

Morphology And Process On The Lateritic Coastline Near Darwin, Northern Australia, R. W. Young, Edward A. Bryant

Faculty of Science - Papers (Archive)

Coastal morphology near Darwin is controlled mainly by the gentle warping of a lateritic profile. In synclines the lateritic cuirasse forms extensive shore platforms, but on the anticlines the pallid zone of the weathering profile is eroded by waves, causing the undercut cuirasse to collapse. The dominant modern process on the shore platforms is solutional attack on the laterite, resulting in large depressions. Many of the platforms are covered by relict layers of cemented laterite cobbles transported by waves of high energy. C14 ages on carbonate cement between the cobbles show that one sheet was deposited at about 3700 BP …

The Hermite Cubic Collocation Approximation To The Eigenvalues And The Eigenfuntions Of The Laplace Operator, Wayne R. Dyksen

Department of Computer Science Technical Reports

No abstract provided.