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Techniques for Estimating Magnitude and Frequency of Floods in South Carolina

Description: Information is presented for estimating the magnitude and frequency of floods on streams in South Carolina. Flood-frequency characteristics for 151 gaging stations were related to basin characteristics by multiple regression techniques for each of four physiographic provinces. Equations were derived to estimate flood magnitudes at recurrence intervals ranging from 2 to 100 years on streams with drainage areas greater than 1.0 square mile. Examples demonstrate the procedure for computing flood-frequency discharge for sites on gaged and ungaged streams in South Carolina. Relationships of flood discharge and frequency to drainage area are presented for the main stem of major streams. A compilation of flood records for gaging stations in South Carolina is presented as supplemental data.
Date: February 1982
Creator: Whetstone, Benjamin H.
Partner: UNT Libraries Government Documents Department

Technique for Estimating the Magnitude and Frequency of Floods in Texas

Description: Abstract: Drainage area, slope, and mean annual precipitation were the only factors that were statistically significant at the 95-percent confidence level when the characteristics of the drainage basins were used as independent variables in a multiple-regression flood-frequency analysis of natural, unregulated streams in Texas. The State was divided into six regions on the basis of the distribution of the residuals from a single statewide regression of the 10-year flood. Equations were developed for predicting the magnitude of floods with recurrence intervals of 2, 5, 10, 25, 50, and 100 years in each of the six regions. These equations are applicable to unregulated rural streams with drainage basins ranging in area from 0.3 square mile to about 5,000 square miles in some regions. Regression equations were not developed for several areas, particularly in south Texas, because of the lack of definition of the flood-frequency characteristics.
Date: 1977
Creator: Schroeder, E. E & Massey, B. C.
Partner: UNT Libraries Government Documents Department

A New Principle of Sound Frequency Analysis

Description: "In connection with the study of aircraft and propeller noises, the National Advisory Committee for Aeronautics has developed an instrument for sound-frequency analysis which differs fundamentally from previous types, and which, owing to its simplicity of principle, construction, and operation, has proved to be of value in this investigation. The method is based on the well-known fact that the Ohmic loss in an electrical resistance is equal to the sum of the losses of the harmonic components of a complex wave, except for the case in which any two components approach or attain vectorial identity, in which case the Ohmic loss is increased by a definite amount" (p. 605).
Date: March 23, 1931
Creator: Theodorsen, Theodore
Partner: UNT Libraries Government Documents Department

Magnitude and Frequency of Floods in Small Drainage Basins in Idaho

Description: Abstract: A method which relates basin characteristics with peak flow characteristics is presented for determining magnitude and frequency of floods on streams with drainage areas between 0.5 and 200 square miles. Regression equations for each of eight regions are presented for determination of the 10-year flood. Peak flows for the 25- and 50-year floods can then be estimated from ratios developed for each region. Regression equations are not developed because of poor definitions for several areas that total about 20,000 square miles. The equations were based on multiple-regression techniques using annual peaks and basin characteristics for 303 gaged sites.
Date: April 1973
Creator: Thomas, C.A.; Harenberg, W. A. & Anderson, J. M.
Partner: UNT Libraries Government Documents Department

Stream Reconnaissance for Nutrients and Other Water-Quality Parameters, Greater Pittsburgh Region, Pennsylvania

Description: Abstract: Eighty-five stream sites in and near the six-county Greater Pittsburgh Region were sampled in mid-June 1971 and again in mid-October 1972. Concentrations of inorganic nitrogen, organic carbon, or phosphorus were high enough to indicate potential problems at about a quarter of the sampling sites. Temperature, dissolved oxygen, and pH values indicated a generally favorable capacity for recovery from degradation, although a number of streams east of the Allegheny and Monongahela Rivers are marginal or lacking. Regionally, sulfate is the dominant ion and was observed in concentrations of 40 milligrams per liter or more at 90 percent of the sites. Bicarbonate exceeded 100 milligrams per liter at 22 sites. A moderate to high degree of mineralization is indicated by conductance readings of more than 500 micromhos per centimeter at half of the sampling sites.
Date: February 1975
Creator: Beall, Robert M.
Partner: UNT Libraries Government Documents Department

Techniques for Estimating Magnitude and Frequency of Floods on Rural Unregulated Streams in New York State Excluding Long Island

Description: Abstract: Techniques are presented for estimating the magnitude and frequency of floods at ungaged sites on unregulated rural streams in New York, excluding Long Island. Discharge-frequency data and basin characteristics of 220 gaging stations in New York and adjacent states were used in multiple linear regression analysis to develop equations for floods that range in recurrence interval from 2 to 100 years. Separate equations were developed for northern, southeastern, and western regions of New York. Drainage area is the independent variable needed in all equations; other variables needed, depending on region, are main-channel slope, storage index, and mean annual precipitation. A method is given for obtaining improved discharge-frequency relationships qt gage sites by weighing log-Pearson Type III and regression estimates according to their variances. Basin characteristics, log-Pearson Type III statistics, and regression and weighted estimates of the discharge-frequency relationship are tabulated for the New York gaging stations used in the regression analysis.
Date: July 1979
Creator: Zembrzuski, Thomas J., Jr. & Dunn, Bernard
Partner: UNT Libraries Government Documents Department

Center for Extended Magnetohydrodynamic Modeling (CEMM) University of Utah SAPP 2007 Final Status Report

Description: During the third and final period of this grant, our goal was to refine the algorithmic approaches used to detect and visualize magnetic islands and their corresponding null points within both the NIMROD and M3D data sets. We refined our geometric approach, which gave a greater confidence in the accuracy of the Poincareplots created. The final results are best demonstrated through Figures 2-6 attached to the report. Technical details this work was reported in both the Physics and Visualization communities. The algorithms used to analyze the magnetic field lines and detect magnetic islands have been packaged into a library and were used within the SCIRun Problem Solving Environment which is being used by members of the CEMM for visualization. In addition, the library interface was developed so that it could be used by both the NIMROD and M3D codes directly. Thus allowing the fusion scientist to perform this analysis while their simulations were actively running. The use of the library for analysis and visualization was not limited to just within the CEMM SciDAC. Other groups such as the SciDAC for the Simulation of Wave Interactions with Magnetohydrodynamics using Silo code have used the tools for the analysis of their simulations, Figure 1. Though the funding of this project had concluded there is still much work to be performed on this analysis. The techniques developed are fast and robust when not in the presence of chaos. Magnetic field lines that are near the separatrices where chaos is most often present can be difficult to analyze yet these are the field lines that are greatest interest. We believe that investigating and developing techniques based on time frequency analysis may hold some promise. Two other issues that need to be address is the ability to automatically search for the magnetic islands and the ...
Date: December 4, 2007
Creator: Sanderson, Allen R. & Johnson, Christopher R.
Partner: UNT Libraries Government Documents Department

Finding Cryptography in Object Code

Description: Finding and identifying Cryptography is a growing concern in the malware analysis community. In this paper, a heuristic method for determining the likelihood that a given function contains a cryptographic algorithm is discussed and the results of applying this method in various environments is shown. The algorithm is based on frequency analysis of opcodes that make up each function within a binary.
Date: October 1, 2008
Creator: Wright, Jason L.
Partner: UNT Libraries Government Documents Department

Stability analysis of a variable-speed wind turbine

Description: This paper examines the elastomechanical stability of a four-bladed wind turbine over a specific rotor speed range. Stability modes, frequencies, and dampings are extracted using a specialized modal processor developed at NREL that post-processes the response data generated by the ADAMS simulation code. The processor can analyze a turbine with an arbitrary number of rotor blades and offers a novel capability of isolating stability modes that become locked at a single frequency. Results indicate that over a certain rotor speed range, the tower lateral mode and the rotor regressive in-plane mode coalesce, resulting in a self-excited instability. Additional results show the effect of tower and nacelle parameters on the stability boundaries.
Date: October 1, 1996
Creator: Bir, G.S.; Wright, A.D. & Butterfield, C.P.
Partner: UNT Libraries Government Documents Department

Statistical damage identification techniques applied to the I-40 bridge over the Rio Grande River

Description: The statistical significance of vibration-based damage identification parameters is studied via application to the data from the tests performed on the Interstate 40 highway bridge in Albuquerque, New Mexico. A test of statistical significance is applied to the mean and confidence interval estimates of the modal properties and the corresponding damage indicators. The damage indicator used in this study is the change in the measured flexibility matrix. Previously presented deterministic results indicate that damage is detectable in all of the damage cases from these data sets. The results of this study indicate that the changes in both the modal properties and the damage indicators are statistically significant for all of the damage cases. However, these changes are distributed spatially for the first three damage cases and do not localize the damage until the fourth and final damage case.
Date: March 1, 1998
Creator: Doebling, S.W. & Farrar, C.R.
Partner: UNT Libraries Government Documents Department

Lg excitation, attenuation, and source spectral scaling in central and eastern North America

Description: Seismic moments and corner frequencies were obtained for many earthquakes in the central and eastern United States, and for a few events in the western United States, using the Lg phase and a recently developed inversion algorithm. Additionally, Q values for the Lg phase along paths to individual stations were obtained simultaneously with the source parameters. Both corner frequencies and magnitudes were found to vary systematically with moment. For moments between 0.15 and 400 x 10{sup 15} N-m corner frequencies vary between about 4 and 0.2 Hz while body-wave magnitude varies between about 3.5 and 5.8. A map of Lg Q values displays a systematic decrease from east and west. Maximum and minimum values are 989 and 160, respectively. Lg coda Q values were obtained for the entire United States with excellent coverage in the eastern and western portions of the country and somewhat poorer coverage in the central portion. Lg coda Q is highest (700-750) in a region of the northeastern United States that includes portions of New York and Pennsylvania and lowest (>200) in California. Lg coda Q is lower (250-450) everywhere west of Rocky Mountains than in the rest of the country (450-750). Q determinations for both the direct Lg phase and Lg coda indicate that, for an earthquake of a given magnitude, Lg and its coda will propagate much more efficiently, and cause damage over a wider area, in the eastern and central United States than it will in the United States.
Date: October 1, 1997
Creator: Mitchell, B.J.; Xie, J. & Baqer, S.
Partner: UNT Libraries Government Documents Department

MEASUREMENT OF NON-LINEARITIES USING SPECTRUM ANALYSIS OF DRIVEN BETATRON OSCILLATION.

Description: Resonance driving terms can be derived from the frequency analysis of turn-by-turn betatron oscillation data. This paper demonstrates that the same information can also be drawn from the spectral analysis of a driven oscillation adiabatically excited by an rf dipole. The advantage of this method is that a large betatron oscillation amplitude can be sustained without loosing the coherence signal. The frequency spectrum of the driven oscillation is composed of multiples of the rf dipole modulation frequency which can be interpreted as resonance driving terms. This analysis has been applied to the data taken at the Brookhaven AGS. The adiabatically excited coherent oscillation is also very useful in measuring the betatron tune parasitically. The data taken during the AGS high intensity proton program is also presented.
Date: June 18, 2001
Creator: BAI,M.; BLASKIEWICZ,M.; LEHRACH,A.; ROSER,T.; SCHMIDT,F. & VAN ASSELT,W.
Partner: UNT Libraries Government Documents Department

Femtosecond Coherent Spectroscopy at 800nm: MI-FROG Measures High-Field Ionization Rates in Gases

Description: The authors report the first quantitative phase-sensitive measurement of ultrafast ionization rates in gases using Multi-phase Interferometric Frequency-Resolved Optical Gating. Ultrafast probe depletion via frequency mixing in the ionization front is observed.
Date: May 24, 1999
Creator: Siders, C.W.; Siders, J.L.W. & Taylor, A.J.
Partner: UNT Libraries Government Documents Department

Application of frequency map analysis to the ALS

Description: Frequency map analysis is a numerical method based on Fourier techniques which provides a clear representation of the global dynamics of many multi-dimensional systems, and which is particularly useful for systems of 3 degrees of freedom and more. The frequency dependence with time also allows refined estimates of the diffusion of the orbits. Here are presented the theoretical foundation of the method, and some applications to the Advanced Light Source, demonstrating how frequency map analysis can be used to understand the limits of the dynamic aperture under various lattice conditions and predict more favorable working points.
Date: January 1, 1996
Creator: Laskar, J. & Robin, D.
Partner: UNT Libraries Government Documents Department

Choppertron II

Description: We present experimental results of a version of the Choppertron microwave generator designed to work with the high emittance beam of the Advanced Test Accelerator (ATA). Simulations showed that a 800-A, 120 {pi} cm-mrad beam (typical of ATA), could produce 800 MW of rf (11.4 GHz) power using two 12-cell, traveling-wave output structures. Funding contraints prevented final tuning of the modulator system and limited the experiment to 530 MW in narrow pulses. Over 400 MW were extracted from a single output structure through fundamental waveguide. Beam breakup was successfully suppressed with >800 amperes transported through the extraction section.
Date: April 25, 1995
Creator: Houck, T.L.; Westenskow, G.A.; Haimson, J. & Mecklenburg, B.
Partner: UNT Libraries Government Documents Department

Evaluation of Tektronix (2 gigasample/second) Digital Signal Analyzer DSA 602

Description: The results of evaluating the Tektronix (2 gigasample/second) Digital Analyzer DSA 602 is discussed. Evaluations were done using both the 11A52 and 11A72 amplifier modules. Effective bits tests were run from 2 MHz to 1 GHz. Timing tests were done to verify repeatability of triggering. Baseline data were taken to determine noise levels. Pulse testing was done to determine overdrive recoverability. The stability of the internal calibration was verified. TDR tests were done to determine what reflections would be generated if the inputs were overdriven. 32 figs., 8 tabs.
Date: January 1, 1990
Creator: Graves, T.
Partner: UNT Libraries Government Documents Department

XAPiir: A recursive digital filtering package

Description: XAPiir is a basic recursive digital filtering package, containing both design and implementation subroutines. XAPiir was developed for the experimental array processor (XAP) software package, and is written in FORTRAN. However, it is intended to be incorporated into any general- or special-purpose signal analysis program. It replaces the older package RECFIL, offering several enhancements. RECFIL is used in several large analysis programs developed at LLNL, including the seismic analysis package SAC, several expert systems (NORSEA and NETSEA), and two general purpose signal analysis packages (SIG and VIEW). This report is divided into two sections: the first describes the use of the subroutine package, and the second, its internal organization. In the first section, the filter design problem is briefly reviewed, along with the definitions of the filter design parameters and their relationship to the subroutine input parameters. In the second section, the internal organization is documented to simplify maintenance and extensions to the package. 5 refs., 9 figs.
Date: September 21, 1990
Creator: Harris, David
Partner: UNT Libraries Government Documents Department

Water Quality of the Neuse River, North Carolina--Variability, Pollution loads, and long-term trends

Description: From abstract: This report presents "a water-quality study of the Neuse River, based on data collected during 1956-77 at the U.S. Geological Survey stations at Clayton and Kinston, employs statistical trend analysis techniques that provide a framework for river-quality assessment." It includes maps, graphs, and tables.
Date: February 29, 1980
Creator: Harned, Douglas A.
Partner: UNT Libraries Government Documents Department

Impact induced response spectrum for the safety evaluation of the high flux isotope reactor

Description: The dynamic impact to the nearby HFIR reactor vessel caused by heavy load drop is analyzed. The impact calculation is carried out by applying the ABAQUS computer code. An impact-induced response spectrum is constructed in order to evaluate whether the HFIR vessel and the shutdown mechanism may be disabled. For the frequency range less than 10 Hz, the maximum spectral velocity of impact is approximately equal to that of the HFIR seismic design-basis spectrum. For the frequency range greater than 10 Hz, the impact-induced response spectrum is shown to cause no effect to the control rod and the shutdown mechanism. An earlier seismic safety assessment for the HFIR control and shutdown mechanism was made by EQE. Based on EQE modal solution that is combined with the impact-induced spectrum, it is concluded that the impact will not cause any damage to the shutdown mechanism, even while the reactor is in operation. The present method suggests a general approach for evaluating the impact induced damage to the reactor by applying the existing finite element modal solution that has been carried out for the seismic evaluation of the reactor.
Date: May 1, 1997
Creator: Chang, S.J.
Partner: UNT Libraries Government Documents Department

Application of nonlinear wave modulation spectroscopy to discern material damage

Description: Materials containing structural damage have a far greater nonlinear elastic response than materials with no structural damage. This is the basis for nonlinear wave diagnostics of damage, methods which are remarkably sensitive to the detection and progression of damage in materials. Here the authors describe one nonlinear method, the application of harmonics and sum and difference frequency to discern damage in materials. The method is termed Nonlinear Wave Modulation Spectroscopy (NWMS). It consists of exciting a sample with continuous waves of two separate frequencies simultaneously, and inspecting the harmonics of the two waves, and their sum and difference frequencies (sidebands). Undamaged materials are essentially linear in their response to the two waves, while the same material, when damaged, becomes highly nonlinear, manifested by harmonics and sideband generation. The authors illustrate the method by experiments on uncracked and cracked plexiglass and sandstone samples, and by applying it to intact and damaged engine components.
Date: April 1, 1999
Creator: Johnson, P.A.; Sutin, A. & Abeele, K.E.A. van den
Partner: UNT Libraries Government Documents Department

An overview of modal-based damage identification methods

Description: This paper provides an overview of methods that examine changes in measured vibration response to detect, locate, and characterize damage in structural and mechanical systems. The basic idea behind this technology is that modal parameters (notably frequencies, mode shapes, and modal damping) are functions of the physical properties of the structure (mass, damping, and stiffness). Therefore, changes in the physical properties will cause detectable changes in the modal properties. The motivation for the development of this technology is first provided. The methods are then categorized according to various criteria such as the level of damage detection provided, model-based vs. non-model-based methods and linear vs. nonlinear methods. This overview is limited to methods that can be adapted to a wide range of structures (i.e., are not dependent on a particular assumed model form for the system such as beam-bending behavior and methods and that are not based on updating finite element models). Next, the methods are described in general terms including difficulties associated with their implementation and their fidelity. Past, current and future-planned applications of this technology to actual engineering systems are summarized. The paper concludes with a discussion of critical issues for future research in the area of modal-based damage identification.
Date: September 1, 1997
Creator: Farrar, C.R. & Doebling, S.W.
Partner: UNT Libraries Government Documents Department

MEASUREMENT OF NON-LINEARITIES USING SPECTRUM ANALYSIS OF DRIVEN BETATRON OSCILLATION.

Description: Resonance driving terms can be derived from the frequency analysis of turn-by-turn betatron oscillation data. This paper demonstrates that the same information can also be drawn from the spectral analysis of a driven oscillation adiabatically excited by an rf dipole. The advantage of this method is that a large betatron oscillation amplitude can be sustained without loosing the coherence signal. The frequency spectrum of the driven oscillation is composed of multiples of the rf dipole modulation frequency which can be interpreted as resonance driving terms. This analysis has been applied to the data taken at the Brookhaven AGS. The adiabatically excited coherent oscillation is also very useful in measuring the betatron tune parasitically. The data taken during the AGS high intensity proton program is also presented.
Date: June 18, 2001
Creator: BAI,M.; BLASKIEWICZ,M.; LEHRACH,A.; ROSER,T.; SCHMIDT,F. & VAN ASSELT,W.
Partner: UNT Libraries Government Documents Department

MCNP-DSP USERS MANUAL

Description: The Monte Carlo code MCNP-DSP was developed from the Los Alamos MCNP4a code to calculate the time and frequency response statistics obtained from subcritical measurements. The code can be used to simulate a variety of subcritical measurements including source-driven noise analysis, Rossi-{alpha}, pulsed source, passive frequency analysis, multiplicity, and Feynman variance measurements. This code can be used to validate Monte Carlo methods and cross section data sets with subcritical measurements and replaces the use of point kinetics models for interpreting subcritical measurements.
Date: January 19, 2001
Creator: Valentine, T.E.
Partner: UNT Libraries Government Documents Department