Graphical methods for variable sampling plans
Simplified technique can be done quickly and without machine assistance. Method provides more accurate quality-level information for given sample sizes.
Teramura, K.↗
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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.↗
General aviation technology assessment
The existing problem areas in general aviation were investigated in order to identify those which can benefit from technological payoffs. The emphasis was placed on acceptance by the pilot/passenger in areas such as performance, safety, handling qualities, ride quality, etc. Inputs were obtained from three sectors: industry; government; and user, although slanted toward the user group. The results should only be considered preliminary due to the small sample sizes of the data. Trends are evident however and a general methodology for allocating effort in future programs is proposed.
Jacobson, I. D.↗
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.↗
A methodology for small scale rural land use mapping in semi-arid developing countries using orbital imagery. Part 6: A low-cost method for land use mapping using simple visual techniques of interpretation
The author has identified the following significant results. It was found that color composite transparencies and monocular magnification provided the best base for land use interpretation. New methods for determining optimum sample sizes and analyzing interpretation accuracy levels were developed. All stages of the methodology were assessed, in the operational sense, during the production of a 1:250,000 rural land use map of Murcia Province, Southeast Spain.
Vangenderen, J. L.↗
Jupiter orbiter lifetime - The hazard of Galilean satellite collision
An assessment of the long-term collision risk is made for an uncontrolled orbiting spacecraft that repeatedly enters the spatial region occupied by the satellites. Numerical data are obtained for 50-year orbit propagations which account approximately for the major perturbative effects of Jupiter oblateness, solar gravity and satellite gravity. A broad statistical viewpoint regarding the question of collision likelihood is adopted and is based on a total sample size of 480 initial orbits distributed among 4 orbit classes, 8 inclinations and 15 initial epochs. Numerical results compare favorably with an analytical prediction formula which shows that eccentric, low-inclination orbits have high collision probability.
Friedlander, A. L.↗
Jupiter orbiter lifetime - The hazard of Galilean satellite collision
An assessment of the long-term collision risk is made for an uncontrolled orbiting spacecraft that repeatedly enters the spatial region occupied by the satellites. Numerical data are obtained for 50-year orbit propagations which account approximately for the major perturbative effects of Jupiter oblateness, solar gravity and satellite gravity. A broad statistical viewpoint regarding the question of collision likelihood is adopted and is based on a total sample size of 480 initial orbits distributed among 4 orbit classes, 8 inclinations and 15 initial epochs. Numerical results compare favorably with an analytical prediction formula which shows that eccentric low-inclination orbits have high collision probability.
Friedlander, A. L.↗
Wheat signature modeling and analysis for improved training statistics
The author has identified the following significant results. The spectral, spatial, and temporal characteristics of wheat and other signatures in LANDSAT multispectral scanner data were examined through empirical analysis and simulation. Irrigation patterns varied widely within Kansas; 88 percent of wheat acreage in Finney was irrigated and 24 percent in Morton, as opposed to less than 3 percent for western 2/3's of the State. The irrigation practice was definitely correlated with the observed spectral response; wheat variety differences produced observable spectral differences due to leaf coloration and different dates of maturation. Between-field differences were generally greater than within-field differences, and boundary pixels produced spectral features distinct from those within field centers. Multiclass boundary pixels contributed much of the observed bias in proportion estimates. The variability between signatures obtained by different draws of training data decreased as the sample size became larger; also, the resulting signatures became more robust and the particular decision threshold value became less important.
Nalepka, R. F.↗
Testing the accuracy of remote sensing land use maps
Some of the main aspects that need to be considered in a remote sensing sampling design are: (1) the frequency that any one land use type (on the ground) is erroneously attributed to another class by the interpreter; (2) the frequency that the wrong land use (as observed on the ground) is erroneously included in any one class by the remote sensing interpreter; (3) the proportion of all land (as determined in the field) that is mistakenly attributed by the interpreter; and (4) the determination of whether the mistakes are random (so that the overall proportions are approximately correct) or subject to a persistent bias. A sampling and statistical testing procedure is presented which allows an approximate answer to each of these aspects. The concept developed and described incorporates the probability of making incorrect interpretations at particular prescribed accuracy levels, for a certain number of errors, for a particular sample size. It is considered that this approach offers a meaningful explanation of the interpretation accuracy level of an entire remote sensing land use survey.
Vangenderen, J. L.↗
The petrogenesis of 77115 and its xenocrysts - Description and preliminary interpretation
77115, a fragment-laden feldspathic pigeonite basalt, is one of four hand specimen-size samples collected from a boulder about 2.5 m across at Station 7, Taurus-Littrow. 77115 crystallized rapidly from a melt at or near the lunar surface and contains a population of xenoliths and xenocrysts which must have come from two or more separate sources. Broad reaction rims present in many of the xenocrysts suggest that cooling of the melt may have been very slow initially and rapid in the latter stage to produce the very fine-grained matrix. If the requirement for two cooling rates can be established, this will favor an endogenous igneous origin rather than an impact origin for the melt. Another interpretation is that the matrix crystallized first, followed by subsolidus reaction between xenocrysts and matrix to form the rims. The Apollo 17 feldspathic pigeonite basalts are postulated to be the dominant rock types of the early lunar crust.
Chao, E. C. T.↗
Reliability of nondestructive evaluation data
Program calculates probability of defects at selected confidence levels from nondestructive evaluation data. It provides alternate method of grouping sample data to obtain reasonable value for lower confidence limit with small sample size.
Couchman, J. C.↗
Decision rules for unbiased inventory estimates
An efficient and accurate procedure for estimating inventories from remote sensing scenes is presented. In place of the conventional and expensive full dimensional Bayes decision rule, a one-dimensional feature extraction and classification technique was employed. It is shown that this efficient decision rule can be used to develop unbiased inventory estimates and that for large sample sizes typical of satellite derived remote sensing scenes, resulting accuracies are comparable or superior to more expensive alternative procedures. Mathematical details of the procedure are provided in the body of the report and in the appendix. Results of a numerical simulation of the technique using statistics obtained from an observed LANDSAT scene are included. The simulation demonstrates the effectiveness of the technique in computing accurate inventory estimates.
Argentiero, P. D.↗
Extreme Mean and Its Applications
Extreme value statistics obtained from normally distributed data are considered. An extreme mean is defined as the mean of p-th probability truncated normal distribution. An unbiased estimate of this extreme mean and its large sample distribution are derived. The distribution of this estimate even for very large samples is found to be nonnormal. Further, as the sample size increases, the variance of the unbiased estimate converges to the Cramer-Rao lower bound. The computer program used to obtain the density and distribution functions of the standardized unbiased estimate, and the confidence intervals of the extreme mean for any data are included for ready application. An example is included to demonstrate the usefulness of extreme mean application.
Swaroop, R.↗
On evaluating clustering procedures for use in classification
The problem of evaluating clustering algorithms and their respective computer programs for use in a preprocessing step for classification is addressed. In clustering for classification the probability of correct classification is suggested as the ultimate measure of accuracy on training data. A means of implementing this criterion and a measure of cluster purity are discussed. Examples are given. A procedure for cluster labeling that is based on cluster purity and sample size is presented.
Pore, M. D.↗
Mass-Loss Buttons Monitor Material Degradation
Small button-sized samples attached to parent materials are simple way of monitoring degradation of parent in harsh environments. Samples determine effects of multiple exposures to environmental extremes without disturbing fit or function of parent. They are less costly and more convenient than complex instrumentation normally required to measure complete temperature/pressure time history of parent component.
Webster, C. N.↗
A contribution to the knowledge of HMX decomposition and application of results
The decomposition of cyclotramethylenetetranitramine (HMX) in the solid and liquid phase was studied by isothermal and nonisothermal heating at atmospheric pressure. Decomposition rates of solid HMX changed with sample size and gaseous environment. Kinetic parameters were obtained from weight loss measurements in the temperature range 229 C - 269 C. These tests also yielded highly porous solid residues. Qualitative aspects of solid and liquid phase decomposition of HMX with additives were also investigated in isothermal and nonisothermal tests.
Kraeutle, K. J.↗
Sympathetic reaction tests and analyses
The critical separation distances for explosive reactions of a solid rocket propellant were measured. Explosive reactions included low order explosion, low order detonation, and high order detonation. The effects of sample size, shape, damage and temperature on sympathetic reaction were determined experimentally. The sympathetic detonation of small cubes of solid rocket propellant was modelled numerically, using the Eulerian reactive hydrodynamic code 2DE with Forest Fire burn rates. The model was applied to cubes of 2.54 - 7.62 cm (1 - 3 in.), with agreement between calculated and experimental results.
Ricardson, D. E.↗
Artifacts in digital images
Three kinds of artifacts unique to digital images are illustrated, namely aliasing caused by undersampling, interference phenomena caused by improper display of images, and harmonic overtones caused by quantization of amplitudes. Special attention is given to undersampling when the sample size and interval are the same. It is noted that this situation is important because it is typical of solid-state cameras. Quantization of image data of necessity introduces energy at harmonic overtones of the image spectrum. This energy is aliased if the frequency of the overtones is greater than 0.5 cycle/pixel. It cannot be selectively removed from the image through filtering, and the best way to suppress it is to maximize the amplification of the sensor before digital encoding.
Lorre, J. J.↗