Physical Sciences and Mathematics Commons^™

Memory Truncation Receivers For Transmultiplexers, Alfred Mertins

Faculty of Informatics - Papers (Archive)

In this paper, the design of optimal receive filter banks for transmultiplexer-based data transmission over frequency selective channels is investigated. A new design strategy based on the principle of memory truncation, rather than equalization, is presented. Through the receive filters, each subchannel is truncated to a certain length, and the actual data detection is then carried out via low-complexity, independently operating Viterbi detectors. Design examples are presented for high-speed transmission over copper wires. The examples show that memory truncation allows significant performance improvements over MMSE equalization.

Low-Mass Spectroscopic Binaries In The Hyades: A Candidate Brown Dwarf Companion, I. Neill Reid, S. Mahoney

Dartmouth Scholarship

We have used the HIRES echelle spectrograph on the Keck I telescope to obtain high-resolution spectroscopy of 51 late-type M dwarfs in the Hyades cluster. Cross-correlating the calibrated data against spectra of white dwarfs allows us to determine heliocentric velocities with an accuracy of ±0.3 km s⁻¹. 27 stars were observed at two epochs in 1997; two stars, RHy 42 and RHy 403, are confirmed spectroscopic binaries. RHy 42 is a double-lined, equal-mass system; RHy 403 is a single-lined, short-period binary, P∼1.275 d. RHy 403A has an absolute magnitude of M_I=10.85, consistent with a mass …

Nondestructive Single-Photon Trigger, John C. Howell, John A. Yeazell

Mathematics, Physics, and Computer Science Faculty Articles and Research

A triggering device sensitive to a single photon is discussed. It is based on a balanced quantum nondemolition (QND) measurement proposed by Chuang and Yamamoto [Phys. Rev. Lett. 76, 4281 (1996)]. The balanced measurement measures the total photon number and obtains no which-path/mode information. Hence, the timing of the photon can be determined without destroying its wave function or entangling the probe field. This could have extensive use in the realization of long-distance quantum communications systems.

Measurement Of Exclusive Ω Electroproduction At Hera, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, G. Abbiendi, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

The exclusive electroproduction of ω mesons, ep → e ω p, has been studied in the kinematic range 3 < Q2 < 20 GeV2, 40 < W < 120 GeV and |t| < 0.6 GeV2 with the ZEUS detector at HERA using an integrated luminosity of 37.7 pb-1. The ω mesons were identified via the decay ω → π+ π- π0. The exclusive cross section in the above kinematic region is σ(ep) → e ω p = 0.108 ± 0.014 (stat.) ± 0.026(syst.) nb. The reaction ep → e φ p, φ → π+ π- π0, has also been measured. The cross sections, as well as the ratios σ γ·p → ωp/σ γ · p → p0p and σ γ · p → ωp/σγ·p → φp, are presented as a function of W and Q2. Thus, for the first time, the properties of ω electroproduction can be compared to those of p0,φ and J/ψ electroproduction at high W. (C) 2000 Elsevier Science B.V.

The Effect Of Spatial And Temporal Accumulation Rate Variability In West Antarctica On Soluble Ion Deposition, K. J. Kreutz, Paul Andrew Mayewski, L. D. Meeker, M. S. Twickler, S. I. Whitlow

Earth Science Faculty Scholarship

Annually‐dated snowpit and ice core records from two areas of West Antarctica are used to investigate spatial accumulation patterns and to evaluate temporal accumulation rate/glaciochemical concentration and flux relationships. Mean accumulation rate gradients in Marie Byrd Land (11–23 gcm⁻²yr⁻¹ over 150 km, decreasing to the south) and Siple Dome (10–18 gcm⁻²yr⁻¹ over 60 km, decreasing to the south) are consistent for at least the last several decades, and demonstrate the influence of the offshore quasi‐permanent Amundsen Sea low pressure system on moisture flux into the region. Local and regional‐scale topography in both regions appears …

Clathrate Structure For Electronic And Electro-Optic Applications, Leonid Grigorian, Peter C. Eklund, Shaoli Fang

Physics and Astronomy Faculty Patents

A method including the steps of (a) depositing a metal layer on a selected portion of a silicon substrate under a first set of predetermined conditions to form an metal silicide layer and an intermediate n-type silicon layer; and (b) exposing the metal silicide layer and the n-type silicon layer to a second set of predetermined conditions to form a silicon clathrate film on the selected portion of the silicon substrate, where the intermediate n-type silicon layer acts to bond the silicon clathrate to the silicon substrate to form a silicon clathrate structure.

Biological Implications Of A Discrete Mathematical Model For Collagen Deposition And Alignment In Dermal Wound Repair, J. C. Dallon, J. A. Sherratt, P. K. Maini, M. W. Ferguson

Faculty Publications

We develop a novel mathematical model for collagen deposition and alignment during dermal wound healing. We focus on the interactions between fibroblasts, modelled as discrete entities, and a continuous extracellular matrix composed of collagen and a fibrin based blood clot. There are four basic interactions assumed in the model: fibroblasts orient the collagen matrix, fibroblasts produce and degrade collagen and fibrin and the matrix directs the fibroblasts and determines the speed of the cells. Several factors which influence the alignment of collagen are examined and related to current anti-scarring therapies using transforming growth factor " The most influential of these …

Relationships Between Abundance Of Physically Complex Habitat And Benthic Macroinvertebrate Community Parameters In The James River, Nelson County, Va, Tammy Lee Shumaker

Theses & Honors Papers

This study shows the importance of structurally complex habitat on abundance and diversity of organisms in a benthic macroinvertebrate community in the James River, Nelson County, Virginia. Structural complexity was manipulated by attaching stones to five concrete blocks (12.8 ± 0.97% coverage; mean ± SE) and comparing organism abundance on these blocks and blocks lacking stones (0% coverage). Concrete blocks were randomly placed at a site in the James River on November 14, 1999 and collected on December 12, 1999. Macroinvertebrates and particulate organic and inorganic matter on the blocks were collected. Total invertebrate abundance, abundance of eight individual taxa, …

Phase Diagram Of Four-Dimensional Dynamical Triangulations With A Boundary, Simon Catterall, Simeon Warner

Physics - All Scholarship

We report on simulations of DT simplicial gravity for manifolds with the topology of the 4-disk. We find evidence for four phases in a two-dimensional parameter space. In two of these the boundary plays no dynamical role and the geometries are equivalent to those observed earlier for the sphere S^4. In another phase the boundary is maximal and the quantum geometry degenerates to a one dimensional branched polymer. In contrast we provide evidence that the fourth phase is effectively three-dimensional. We find discontinuous phase transitions at all the phase boundaries.

Transient Spin Structures At The Antifero-To-Paramagnetic Phase Boundary Of Febr2, Christian Binek

Christian Binek Publications

Excess magnetization and anomalous susceptibility loss is observed on antiferromagnetic FeBr2 in an axial field H below and above its H-T-phase boundary between the multicritical temperature (Tm = 4.6 K) and the Néel temperature (TN = 14.1 K). These and other unusual properties of FeBr2 are attributed to frustration-induced intraplanar non-critical spin fluctuations, which can be simulated within the framework of a triaxial version of the 2D-ANNNI model.

Crossover From Transient Spin Structures Ot The Field-Induced Griffiths Phase Of Febr2, Christian Binek

Christian Binek Publications

In the presence of an applied axial magnetic field Ha the uniaxial antiferromagnets FeCl2 and FeBr2 show fluctuating domain-like antiferromagnetic correlations above the phase boundary Tc(Ha). They are detected by SQUID measurements of the low frequency out-of-phase susceptibility gc″ and indicate a field-induced Griffiths phase at temperatures Tc(Ha) < T < TN. In contrast to FeCl2, important additional frustration-induced intraplanar non-critical contributions to χ″ vs. T are found in FeBr2. For external fields above the Tc(Ha) line, Ha > 2.6 MA/m, they are shown to superimpose linearly on the Griffiths contributions. These dominate at Ha = 2.67 MA/m and are unequivocally modeled within the Landau theory of fluctuations near phase transitions by introducing a Lorentzian Tc distribution.

Optimal Token Allocations In Solitaire Knock'm Down, Arthur T. Benjamin, Mark L. Huber, Matthew T. Fluet '99

All HMC Faculty Publications and Research

In the game Knock 'm Down, tokens are placed in N bins. At each step of the game, a bin is chosen at random according to a fixed probability distribution. If a token remains in that bin, it is removed. When all the tokens have been removed, the player is done. In the solitaire version of this game, the goal is to minimize the expected number of moves needed to remove all the tokens. Here we present necessary conditions on the number of tokens needed for each bin in an optimal solution, leading to an asymptotic solution.

Limits On Light Gravitino Production And New Processes With Large Missing Transverse Energy In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

Events collected by the Collider Detector at Fermilab (CDF) with an energetic jet plus large missing transverse energy can be used to search for physics beyond the standard model. We see no deviations from the expected backgrounds and set upper limits on the production of new processes. We consider in addition the production of light gravitinos and set a limit at 95% confidence level on the breaking scale √F ≥ 217 GeV, which excludes gravitino masses smaller than 1.1 x 10^-5 eV/c².

Does Elevated Nitrogen And Sulfur Deposition Lead To Net Base Cation Losses In Northern New England Forest Soils?, Ivan J. Fernandez, Stephen A. Norton, Jeffrey Kahl, Lindsey E. Rustad

University of Maine Office of Research Administration: Grant Reports

The aims of this research are to continue treatment and monitoring of a paired watershed experiment at Bear Brook in northern Maine, with an emphasis on changes in soil base cations, particularly calcium. Base cation depletion is well-recognised as a potential problem in soils that have been subjected to acidic N deposition but few data exist from well-controlled, long-term experiments. The Bear Brook watershed has been periodically treated with ammonium sulfate since the fall of 1989 and is believed to be approaching N saturation. Since 1993 the relationship between base cations and strong acid anions has changed, such that labile …

Measurement Of The Proton Structure Function F2 At Very Low Q2 At Hera, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, G. Abbiendi, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti, G. Levi

Faculty Publications

A measurement of the proton structure function F2(x, Q2) is presented in the kinematic range 0.045 GeV2 < Q2 < 0.65 GeV2 and 6 · 10-7 < x < 1 · 10-3. The results were obtained using a data sample corresponding to an integrated luminosity of 3.9pb-1 in e+ p reactions recorded with the ZEUS detector at HERA. Information from a silicon-strip tracking detector, installed in front of the small electromagnetic calorimeter used to measure the energy of the final-state positron at small scattering angles, together with an enhanced simulation of the hadronic final state, has permitted the extension of the kinematic range beyond that of previous measurements. The uncertainties in F2 are typically less than 4%. At the low Q2 values of the present measurement, the rise of F2 at low x is slower than observed in HERA data at higher Q2 and can be described by Regge theory with a constant logarithmic slope δlnF2/δln(1/x). The dependence of F2 on Q2 is stronger than at higher Q2 values, approaching, at the lowest Q2 values of this measurement, a region where F2 becomes nearly proportional to Q2. (C) 2000 Elsevier Science B.V.

Bioindication Of Atmospheric Heavy Metal Deposition In The Blue Ridge Using The Moss Thuidium Delcatulum, Johathan Scott Schilling

Theses & Honors Papers

Heavy metals in the environment pose a risk to human health as well as to ecosystem health. These metals are released into the atmosphere as a result of industrial processes, and can be transported away from their sources to be deposited into the environment. Ectohydric mosses are known accumulators of atmospheric heavy metals, and their tissue can be used to quantify integrated deposition of these metals over time in the ecosystem.

In this study, the moss Thuidium delicatulum (Hedw.) was used to quantify lead (Pb), copper (Cu), chromium (Cr), and nickel (Ni) concentrations in the central Blue Ridge of Virginia …

Jet Engine Certification Standards, Paul Eschenfelder

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

The ability of modern jet engines to ingest birds and continue to operate is largely misunderstood or not contemplated at all in the aviation industry. Currently, there is not one jet engine operating in the world that is certified to ingest one large bird (goose, swan, stork, pelican, vulture, etc) and continue to operate. The effort to harmonize bird ingestion rules between the FAA and JAA has failed. Controversy erupted in recent certification meetings regarding the database being used to certify engines. Additionally, should only rotating engine parts meet certain standards, or all engine parts exposed to impact meet standards? …

Wildlife Management Tools – What’S In Your Toolbox?, John E. Ostrom

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Airport managers of today are faced with a variety of choices of what tools to use to deal with their wildlife problems. The Airside Operations staff of the Minneapolis-St. Paul International Airport (MSP), has developed a “Wildlife Toolbox” which offers an assortment of programs, systems and devices to best deal with problem wildlife at a large northern tier hub airport. This “toolbox”, developed over time, includes not only the basics needed by an Airport Manager, but some rather unique tools that managers should consider when developing their own toolboxes.

Lasers As Nonlethal Avian Repellents: Preliminary Experiments, Bradley F. Blackwell, Glen E. Bernhardt

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Laser technology has recently been demonstrated as a potentially effective avian repellent; however, controlled studies have not been reported. We conducted 2-choice cage tests to quantify the effectiveness of low-power (10−60-mW) 633−650-nm lasers in preventing Brown-headed Cowbirds (Molothrus ater), European Starlings (Sturnus vulgaris), and Rock Doves (Columbia livia) from perching and Canada Geese (Branta canadensis) and Mallards (Anas platyrhynchos) from use of grass plots. In 3 experiments with stationary and moving laser beams “defending” a randomly selected perch, brown-headed cowbirds were not repelled, nor did they exhibit behaviors indicating perception …

Flight Control As A Goose Deterrent At Portland International Airport, Sharon Gordon, Noel Lyman

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Geese pose a threat to aircraft worldwide. The anthraquinone formula “Flight Control” (FC) is marketed as a deterrent to grazing geese, through an ultraviolet and post-ingestional repellency. The Port of Portland conducted a test to address six objectives regarding the effectiveness of Flight Control. A field with heavy goose activity was divided into five transects, two of which had goose activity 65 percent of the 22 days monitored. These two plots were sprayed using a mixture of one-half gallon of FC, five gallons of water, and eight ounces of an agricultural sticker. This was applied at a rate of one-half …

Canada Goose Management At The Minneapolis-St. Paul International And Downtown St. Paul Airports, James A. Cooper

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

The Metropolitan Airports Commission initiated a Canada goose control program at the Minneapolis-St. Paul International Airport (MSP) in 1984, and the Downtown St. Paul Airport (DTSP) in 1994. Flightless geese within 16 km of these airports were trapped, neck-banded, and observed and counted weekly from September to December (MSP) and February (DTSP). Efficacy was measured by observing fall goose flights through the operations airspace in 1984-87, 1998-1999 (MSP) and 1994-1999 (DTSP). A total of 2,587 geese were removed from 36 MSP sites and 2,163 from 12 DTSP sites. From 1990 to 1999, 535 nests containing 2,637 eggs were destroyed and …

Bird Strike Trends And Bird Harassment Efforts In China, Zhou Ming Jun

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

China is a large developing country. Under recent policies, the aviation industry has grown quickly. The bird-strike events have also increased rapidly, with 170 birdstrikes recorded from 1991 to 1997. The Civil Aviation Administration of China (CAAC) monitored these trends closely, and ABSAC was formed. We imported some products from the USA, which imitated a bird’s distress call, but these products didn’t work well in China. CAAC entrusted Tsinghua University to solve this problem. SBS company of Tsinghua University, led by Professor Xi Boa Shu took this task. For two years, SBS manufactured a series of products to prevent birdstrikes. …

Development Of A Bird Avoidance Model For Naval Air Facility El Centro, California, Edward Zakrajsek, John Bissonette, Tricia Cutler

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Two weeks after the Elmendorf AFB-AWACS crash (22 September 1995), the US Navy lost an F-18 Hornet to a birdstrike at Naval Air Facility El Centro (NAFEC) in southern California. NAFEC is surrounded by agricultural land where crops are grown year round, and its location just 26-km south of the Salton Sea National Wildlife Refuge suggests a very high probability of additional serious birdstrikes in the future. We are developing a computer-based Bird-Avoidance Model for the airfield and its two associated bombing ranges, to decrease the number of damaging birdstrikes. We are currently conducting bird counts to assess the distribution …

Utility Of Tdwr And Asr-9 Data To Mitigate Bird Strikes At Commercial Airports, Mark A. Isaminger, Mark E. Weber

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Conflicts between birds and commercial aircraft are a noteworthy problem at both large and small airports. The risk factor for U.S. airports continues to increase due to the steady rise in take-off/landings and bird populations. The focus of bird strike mitigation in the past has centered primarily on Wildlife Management techniques. Recently, an Avian Hazard Advisory System (AHAS) has been developed to reduce the risks of bird strikes to military operations. This system uses a mosaic of data collected by the Next Generation Weather Radar (NEXRAD). This sensor serves as an excellent tool for enroute bird advisories due to the …

Potential Use Of On-Board Radar For Bird Detection And Avoidance, Pete Stephan

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

An approach to the reduction of military bird strike costs is proposed. Financial return-on-investment would be maximized by focusing on the most expensive bird strikes without requiring new investment in hardware. Most of the dollar cost of military bird strikes results from strikes in the military-unique high-speed/low-altitude flight regime over remote areas. Avoiding these birds motivates a short time from detection of the bird until the pilot avoidance response because single raptors are now causing a large fraction of the losses. Ground-based sensors with communications links to pilots would be expensive because of the geographic extent of the ranges where …

Deer Management At Airports: A Case Study, J. Harris Glass

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Deer living on and around airports pose a threat to aircraft. The consequence of a deer-aircraft strike can be serious and potentially tragic. Nationally, cervids (deer) accounted for 67% of all reported mammal-aircraft strikes and have caused damage in 81% of deer strikes in the United States (Cleary et al. 1999). Due to the potential for damage, the Federal Aviation Administration and USDA-APHIS-Wildlife Services (WS) program recommend a zero-tolerance of deer on an airfield. Deer densities at Newport News / Williamsburg International Airport (PHF) were as high as 171.5 deer/mi² at the onset of the Wildlife Hazard Assessment conducted …

The Avian Hazard Advisory System (Ahas): Operational Use Of Weather Radar For Reducing Bird Strike Risk In North America, T. Adam Kelly, Ron Merritt, Andreas Smith, Mark Howera, Ron White

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

The Avian Hazard Advisory System (AHAS) was developed to use NEXRAD weather radar data and National Weather Service (NWS) weather data to forecast and monitor bird activity. The system was tested in a pilot study in 1998 and became operational for the eastern 1/3 of the USA in March 2000. Two thousand low level routes, ranges, airspace and military airfields are evaluated every hour. The monitoring of birds in near real time uses algorithms developed by Geo-Marine, Inc to isolate biological targets from weather. Removing the weather returns permits subsequent processing to retrieve information on bird strike risk to be …

Current Status Of The Usaf Bird Avoidance Model (Bam), Russell P. Defusco

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

The United States Air Force (USAF) Bird Aircraft Strike Hazard (BASH) Team has been developing versions of a Bird Avoidance Model (BAM) since the early 1980’s. In the developmental phases of the first models, it was recognized that avoiding birds on low-level routes and ranges was the only solution to the significant problem of bird strikes to these military operations nationwide. The early versions of BAM were limited in coverage, biological data, and resolution. With the advent of sophisticated Geographic Information System (GIS) technology and advances in computational capability, modern versions of the USAF BAM have become increasingly robust and …

The Relationship Between Bird Strikes And Weather: A Detailed Species Based Analysis, John Allan, Susan Manktelow, Jennifer Bell

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

Bird controllers have recognized for many years that the frequency of bird strikes is related in some way to weather conditions. Previous studies have demonstrated a relationship between bird strike frequency and rainfall on certain airfields. This paper takes bird strike data from five major UK airports and relates them to a variety of weather parameters. It then examines the relationships found on a species by species basis and uses differences in the ecology of the birds involved to suggest the mechanisms by which weather may influence bird strike frequency. The data can be used to better target bird control …

Faa Perspective On Future Directions Of Research And Development To Reduce The Bird Strike Threat, Michel J. Hovan, William J. Hughes

Bird Strike Committee-USA/Canada Joint Annual Meeting: 2nd (2000)

As bird strike risks keep increasing, the FAA is actively sponsoring research to minimize these risks. Bird strike risk reduction falls under the area of wildlife mitigation research. In this endeavor, FAA Research and Development faces challenges of budgetary and technical nature. From the budgetary standpoint, R&D funds were until recently very limited and the FAA could not carry out a comprehensive program in this area. Although still under funded, the wildlife mitigation R&D allocation has steadily improved and plans can now be made for the future. At the technical level, the areas of research for bird strike risks reductions …