Engineering topics

Crutcher, H. L.

Publications and source records attributed to Crutcher, H. L..

16 records

NASA NTRS2007

An Overview of Climatic Elements

This Technical Publication (TP) addresses some climatic elements with emphasis on atmospheric composition, including gas radiative characteristics. Solar radiation is discussed with considerable information on the mathematical and statistical formulae. On a worldwide basis, temperature and precipitation for the globe are discussed along with interaction in drought. Also included is the simultaneous interaction with winds, humidity, and solar radiation. Volcanology gets minimum treatment. The oceans and seas are treated in chart form along with the interrelationship of oceanic currents and El Nino and La Nina, and ENSO phenomena. Upper air circulations are discussed. Various cloud formations up to 85-95 km altitude are described. Information on tornadoes and hurricanes is also included. One section is devoted to the climate physical-chemical elements. A short discussion is given on the importance for the quality of data and/or information in descriptions of the climate. This TP presents only an overview or survey of these and other various climatic elements.

Crutcher, H. L.↗

NASA NTRS1977

Multivariate-normality goodness-of-fit tests

Computer program applies chi-square Pearson test to multivariate statistics for application in any field in which data of two or more variables (dimensions) are sampled for statistical purposes. Program handles dimensions two through five, with up to thousand data sets.

Falls, L. W.↗

NASA NTRS1976

Multivariate normality

Sets of experimentally determined or routinely observed data provide information about the past, present and, hopefully, future sets of similarly produced data. An infinite set of statistical models exists which may be used to describe the data sets. The normal distribution is one model. If it serves at all, it serves well. If a data set, or a transformation of the set, representative of a larger population can be described by the normal distribution, then valid statistical inferences can be drawn. There are several tests which may be applied to a data set to determine whether the univariate normal model adequately describes the set. The chi-square test based on Pearson's work in the late nineteenth and early twentieth centuries is often used. Like all tests, it has some weaknesses which are discussed in elementary texts. Extension of the chi-square test to the multivariate normal model is provided. Tables and graphs permit easier application of the test in the higher dimensions. Several examples, using recorded data, illustrate the procedures. Tests of maximum absolute differences, mean sum of squares of residuals, runs and changes of sign are included in these tests. Dimensions one through five with selected sample sizes 11 to 101 are used to illustrate the statistical tests developed.

Crutcher, H. L.↗

NASA NTRS1976

Determination of statistics for any rotation of axes of a bivariate normal elliptical distribution

Transformation of statistics from a dimensional set to another dimensional set involves linear functions of the original set of statistics. Similarly, linear functions will transform statistics within a dimensional set such that the new statistics are relevant to a new set of coordinate axes. A restricted case of the latter is the rotation of axes in a coordinate system involving any two correlated random variables. A special case is the transformation for horizontal wind distributions. Wind statistics are usually provided in terms of wind speed and direction (measured clockwise from north) or in east-west and north-south components. A direct application of this technique allows the determination of appropriate wind statistics parallel and normal to any preselected flight path of a space vehicle. Among the constraints for launching space vehicles are critical values selected from the distribution of the expected winds parallel to and normal to the flight path. These procedures are applied to space vehicle launches at Cape Kennedy, Florida.

Falls, L. W.↗

NASA NTRS1975

Revised prediction (estimation) of Cape Kennedy, Florida, wind speed profile

The prediction of the wind profile maximum speed at Cape Kennedy, Florida, is made for any selected calendar data. The prediction is based on a normal probability distribution model with 15 years of smoothed input data and is static in the sense that no dynamic principles of persistence or synoptic features are considered. Comparison with similar predictions based on 6 years of data shows the same general pattern, but the variability decreased with the increase of sample size.

Guttman, N. B.↗

NASA NTRS1971