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Experimental Mathematics and Computational Statistics

Description: The field of statistics has long been noted for techniques to detect patterns and regularities in numerical data. In this article we explore connections between statistics and the emerging field of 'experimental mathematics'. These includes both applications of experimental mathematics in statistics, as well as statistical methods applied to computational mathematics.
Date: April 30, 2009
Creator: Bailey, David H. & Borwein, Jonathan M.
Partner: UNT Libraries Government Documents Department

Correlations involving pressure fluctuations in homogeneous turbulence

Description: Report presenting an investigation of the correlations of pressure with itself and of pressure with two velocity components for the case of isotropic turbulence. The correlations are expressed in terms of correlations involving two velocity components at a point and two velocity components at another point.
Date: January 1954
Creator: Uberoi, Mahinder S.
Partner: UNT Libraries Government Documents Department

Supporting information for Abraham model correlations for solute partitioning into o-xylene, m-xylene and p-xylene from both water and the gas phase

Description: This document includes supporting information and figures for an article on the Abraham model correlations for solute partitioning into o-xylene, m-xylene and p-xylene from both water and the gas phase.
Date: September 2011
Creator: Stephens, Timothy W.; De la Rosa, Nohelli E.; Saifullah, Mariam; Ye, Shulin; Quay, Amanda N.; Chou, Vicky et al.
Partner: UNT College of Arts and Sciences

Correlation of engine-cooling data

Description: Report discusses a method of correlating engine-cooling data and its application to a representative engine-cooling test. Considerations for the correlation method are given, but the application to specific engine-cooling problems should be simple and direct. Information about experimental procedure and an example with specific values are included.
Date: January 1945
Creator: Brimley, D. E. & Brevoort, Maurice J.
Partner: UNT Libraries Government Documents Department

Abraham model correlations for solute partitioning into o-xylene, m-xylene and p-xylene from both water and the gas phase

Description: Article on Abraham model correlations for solute partitioning into o-xylene, m-xylene and p-xylene from both water and the gas phase.
Date: September 2011
Creator: Stephens, Timothy W.; De la Rosa, Nohelli E.; Saifullah, Mariam; Ye, Shulin; Chou, Vicky; Quay, Amanda N. et al.
Partner: UNT College of Arts and Sciences

Some Measurements of Time and Space Correlation in Wind Tunnel

Description: Results are presented of research obtained by means of an apparatus for measurement of time and space correlation and of a spectral analyzer in the study of the longitudinal component of turbulence velocities in a wind tunnel downstream of a grid of meshes. Application to the case of a flat-plate boundary layer is illustrated. These researches were made at the Laboratoire de Mecanique de l'Atmosphere de l'I.M.F.M. for the O.N.E.R.A.
Date: February 1955
Creator: Favre, A.; Gaviglio, J. & Dumas, R.
Partner: UNT Libraries Government Documents Department

Correlation of wind-tunnel predictions with flight tests of a twin-engine airplane 1: longitudinal-stability and -control characteristics

Description: From Summary: "The longitudinal-stability and -control characteristics of a twin-engine patrol airplane as predicted from the results of wind-tunnel tests of a powered model and as measured in flight are compared in this report. The accuracy of the wind-tunnel predictions and the reasons for discrepancies are analyzed and discussed."
Date: April 1945
Creator: Delany, Noel K. & Kauffman, William M.
Partner: UNT Libraries Government Documents Department

Correlation of wind-tunnel predictions with flight tests of a twin-engine patrol airplane 2: lateral- and directional-stability and control characteristics

Description: From Summary: "The lateral- and directional-stability and -control characteristics of a twin-engine patrol airplane as predicted from the results of wind-tunnel tests of a powered model and as measured in flight are compared in this report. The predictions from wind-tunnel-test data were in good agreement with the flight-test results. The results show that such predicted flying-qualities characteristics are sufficiently accurate to indicate the unsatisfactory lateral- and directional-stability and -control characteristics of airplanes in the preliminary design stage."
Date: August 30, 1945
Creator: Delany, Noel K. & Kauffman, William M.
Partner: UNT Libraries Government Documents Department

A comparison of traditional and IRT factor analysis.

Description: This study investigated the item parameter recovery of two methods of factor analysis. The methods researched were a traditional factor analysis of tetrachoric correlation coefficients and an IRT approach to factor analysis which utilizes marginal maximum likelihood estimation using an EM algorithm (MMLE-EM). Dichotomous item response data was generated under the 2-parameter normal ogive model (2PNOM) using PARDSIM software. Examinee abilities were sampled from both the standard normal and uniform distributions. True item discrimination, a, was normal with a mean of .75 and a standard deviation of .10. True b, item difficulty, was specified as uniform [-2, 2]. The two distributions of abilities were completely crossed with three test lengths (n= 30, 60, and 100) and three sample sizes (N = 50, 500, and 1000). Each of the 18 conditions was replicated 5 times, resulting in 90 datasets. PRELIS software was used to conduct a traditional factor analysis on the tetrachoric correlations. The IRT approach to factor analysis was conducted using BILOG 3 software. Parameter recovery was evaluated in terms of root mean square error, average signed bias, and Pearson correlations between estimated and true item parameters. ANOVAs were conducted to identify systematic differences in error indices. Based on many of the indices, it appears the IRT approach to factor analysis recovers item parameters better than the traditional approach studied. Future research should compare other methods of factor analysis to MMLE-EM under various non-normal distributions of abilities.
Date: December 2004
Creator: Kay, Cheryl Ann
Partner: UNT Libraries

Empirical Correlations for Thermal Flowmeters Covering a Wide Range of Thermal-Physical Properties

Description: Thermal flowmeters can provide direct mass flow measurement of gases and vapors over a wide range of process conditions without the need for density corrections based on pressure and temperature. They are widely used in industrial processes that contain toxic, corrosive, or highly reactive gases. It is often not possible to calibrate the flowmeter on the process gas in which it will be used. In this case a non-hazardous �surrogate� gas is used for calibration, and a theoretical model used to predict the meter�s response in the process gas. This can lead to large measurement errors because there are no accurate and straightforward methods for predicting the performance on one kind of gas based on the calibration on another gas because of the complexity of the thermal processes within the flow sensor. This paper describes some of the commonly used models and conversion methods and presents work done at ORNL to develop and experimentally verify better thermal models for predicting flowmeter performance.
Date: July 19, 1999
Creator: Hardy, J.E.; Hylton, J.O. & McKnight, T.E.
Partner: UNT Libraries Government Documents Department

Two-Fold Role of Randomness: A Source of Both Long-Range Correlations and Ordinary Statistical Mechanics

Description: The role of randomness as a generator of long range correlations and ordinary statistical mechanics is investigated in this Dissertation. The difficulties about the derivation of thermodynamics from mechanics are pointed out and the connection between the ordinary fluctuation-dissipation process and possible anomalous properties of statistical systems is highlighted.
Date: December 1998
Creator: Rocco, A. (Andrea)
Partner: UNT Libraries

Nanostructural engineering of organic aerogels

Description: Aerogels are a special class of open-cell foams with an ultrafine cell/pore size (<50 nm), high surface area (400-1100 M{sup 2}/g), and a solid matrix composed of interconnected colloidal-like particles or fibers with characteristic diameters of 10 nm. This paper examines the correlation between nanostructure and thermal conductivity in a series of resorcinol-formaldehyde (RF) aerogels prepared under different synthetic conditions.
Date: March 1, 1995
Creator: Pekala, R.W.; Alviso, C.T.; Lu, X.; Caps, R. & Frocle, J.
Partner: UNT Libraries Government Documents Department

Decoherence and a simple quantum computer

Description: The authors analyze the effect of decoherence on the operation of part of a simple quantum computer. The results indicate that quantum bit coding techniques may be used to mitigate the effects of two sources of decoherence - amplitude damping and phase randomization.
Date: October 1, 1995
Creator: Chuang, I.L.; Yamamoto, Y. & Laflamme, R.
Partner: UNT Libraries Government Documents Department

Disappearance of back-to-back high p {sub T} hadron correlations in central Au+Au collisions at {radical}s{sub NN} = 200 GeV

Description: Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudo-rapidity range and full azimuth in Au+Au and p+p collisions at = {radical}s{sub NN} = 200 GeV. The small-angle correlations observed in p+p collisions and at all centralities of Au+Au collisions are characteristic of hard-scattering processes already observed in elementary collisions. A strong back-to-back correlation exists for p+p and peripheral Au + Au. In contrast, the back-to-back correlations are reduced considerably in the most central Au+Au collisions, indicating substantial interaction as the hard-scattered partons or their fragmentation products traverse the medium.
Date: October 25, 2002
Creator: Adler, C.; Ahammed, Z.; Allgower, C.; Amonett, J.; Anderson, B.D.; Anderson, M. et al.
Partner: UNT Libraries Government Documents Department

Moments for general quadratic densities in n dimensions

Description: We present the calculation of the generating functions and the rth-order correlations for densities of the form {rho}(x) {proportional_to} where g(s) is a non-negative function of the quadratic ''action'' s(x)={summation}{sub i,j}H{sub ij}x{sub i}x{sub j}, where x = (x{sub 1},x{sub 2}...,x{sub n}) is a real n-dimensional vector and H is a real, symmetric n x n matrix whose eigenvalues are strictly positive. In particular, we find the connection between the (r+2)th-order and rth-order correlations, which constitutes a generalization of the Gaussian moment theorem, which corresponds to the particular choice g(s)=e{sup -s/2}. We present several examples for specific choices for g(s), including the explicit expression for the generating function for each case and the subspace projection of {rho}(x) in a few cases. We also provide the straightforward generalizations to: (1) the case where g=g(s(x)+a {center_dot} x), where a=(a{sub 1},a{sub 2},...,a{sub n}) is an arbitrary real n-dimensional vector, and (2) the complex case, in which the action is of the form s(z) = {summation}{sub i,j}H{sub ij}z{sup *}{sub i} z{sub j} where z=(z{sub 1},z{sub 2}...z{sub n}) is an n-dimensional complex vector and H is a Hermitian n x n matrix whose eigenvalues are strictly positive.
Date: March 20, 2002
Creator: Furman, Miguel A.
Partner: UNT Libraries Government Documents Department

DIRECT MEASUREMENT OF HEAT FLUX FROM COOLING LAKE THERMAL IMAGERY

Description: Laboratory experiments show a linear relationship between the total heat flux from a water surface to air and the standard deviation of the surface temperature field, {sigma}, derived from thermal images of the water surface over a range of heat fluxes from 400 to 1800 Wm{sup -2}. Thermal imagery and surface data were collected at two power plant cooling lakes to determine if the laboratory relationship between heat flux and {sigma} exists in large heated bodies of water. The heat fluxes computed from the cooling lake data range from 200 to 1400 Wm{sup -2}. The linear relationship between {sigma} and Q is evident in the cooling lake data, but it is necessary to apply band pass filtering to the thermal imagery to remove camera artifacts and non-convective thermal gradients. The correlation between {sigma} and Q is improved if a correction to the measured {sigma} is made that accounts for wind speed effects on the thermal convection. Based on more than a thousand cooling lake images, the correlation coefficients between {sigma} and Q ranged from about 0.8 to 0.9.
Date: December 19, 2007
Creator: Garrett, A; Eliel Villa-Aleman, E; Robert Kurzeja, R; Malcolm Pendergast, M; Timothy Brown, T & Saleem Salaymeh, S
Partner: UNT Libraries Government Documents Department

CORRELATION BETWEEN RAINFALL PATTERNS AND THE WATER TABLE IN THEGENERAL SEPARATIONS AREA OF THE SAVANNAH RIVERSITE

Description: The objective of the study was to evaluate rainfall and water table elevation data in search of a correlation that could be used to understand and predict water elevation changes. This information will be useful in placing screen zones for future monitoring wells and operations of groundwater treatment units. Fifteen wells in the General Separations Area (GSA) at Savannah River Site were evaluated from 1986 through 2001. The study revealed that the water table does respond to rainfall with minimal delay. (Water level information was available monthly, which restricted the ability to evaluate a shorter delay period.) Water elevations were found to be related to the cumulative sum (Q-Delta Sum) of the difference between the average rainfall for a specific month and the actual rainfall for that month, calculated from an arbitrary starting point. Water table elevations could also be correlated between wells, but using the right well for correlation was very important. The strongest correlation utilized a quadratic equation that takes into account the rainfall in a specific area and the rainfall from an adjacent area that contributes through a horizontal flow. Specific values vary from well to well as a result of geometry and underground variations. R2's for the best models ranged up to 0.96. The data in the report references only GSA wells but other wells (including confined water tables) on the site have been observed to return similar water level fluctuation patterns.
Date: August 10, 2009
Creator: Smith, C.
Partner: UNT Libraries Government Documents Department