Showing papers on "Test data published in 1971"

Theory of Incomplete Models of Dynamic Structures

Abstract: A method is presented for identifying parameters in a linear, discrete model of a structure by using measured normal modes to modify an analytically derived model. The structure considered has a relatively large number of points of interest and a frequency range of interest influenced by a relatively small number of normal modes. The analytical model which is introduced has fewer degrees of freedom (normal modes) than coordinates (points of interest). The parameters of this "incomplete model" are obtainable from the limited, but quantitative, test data, and the conceptually valid, but approximate, analytical data. The characteristics of this model and methods of using it are discussed, in particular, means of computing the effects of mass and stiffness changes on natural frequencies and normal modes. Computer experiments illustrate these methods and demonstrate that such a model can be useful and that the procedure is not overly sensitive to measurement errors.

Engineering Analysis of the Inelastic Stress Response of a Structural Metal Under Variable Cyclic Strains

Abstract: Inelastic stress response under strain cycling conditions is analyzed in terms of the three important governing phenomena, namely, memory of prior history, cyclic hardening or softening, and cyclic mean stress relaxation.Independent formulations to describe these respective features consist of a set of hysteresis rules, a set of transient stress-strain relations, and an empirical exponential model. A new approach to accurately describe the hysteresis loop shape characteristics is also presented. While strain amplitude and number of cycles are used as the primary variables influencing cyclic hardening, softening, and relaxation, the effect of other variables on these features and hence their mutual interactions are observed to be small. Therefore, as a first approximation it is postulated that independent formulations based on constant amplitude test data are applicable to spectrum loading situations. Computer based models resulting from this analysis are suitable for predicting the cyclic stress-strain and fatigue response of ductile structural metals and also provide a basis for developing general flexural response models.

The Heuristic DENDRAL program for explaining empirical data

Abstract: The Heuristic DENDRAL program uses an information processing model of scientific reasoning to explain experimental data in organic chemistry. This report summarizes the organization and results of the program for computer scientists. The program is divided into three main parts: planning, structure generation, and evaluation. The planning phase infers constraints on the search space from the empirical data input to the system. The structure generation phase searches a tree whose termini are models of chemical molecules using pruning heuristics of various kinds. The evaluation phase tests the candidate structures against the original data. Results of the program''s analyses of some test data are discussed.

Type-Curve Solution of Step-Drawdown Test

Abstract: A set of type-curves is presented which simplifies and quickens the solution of the Rorabaugh equation for drawdown in a pumping well by eliminating the trial-and-error computations. Type-curve analysis of test data in the field, before pumping is discontinued, provides an indication of the accuracy and adequacy of test data points. For optimum accuracy, test data should cover the portion of maximum curvature of the curve, and the range between the lowest and the highest pumping rates used in the step-drawdown test should be great enough to define a unique curve.

Medical test data entry terminal

Abstract: A terminal for the real time entry of medical test data into the computer based medical record of a patient. The terminal is operative only by an operator whose identification has been verified, and test data is visually verified before entry into the patient record.

Selection and performance of vibration tests

Abstract: : ;Contents: Introduction; Selection of appropriate test method; Simulation characteristics of test methods; Vibration equipment requirements; Test performance and control; Acquisition and processing of test data.

A General Data Format for Summarizing Taxonomic Information

Abstract: The increasing use of computers and information systems in systematic biology now makes desirable the development of a general data format for summarizing and communicating taxonomic information. Such a format should be acceptable to the biologist and to the computer. It must be compatible with the major programming languages and with commonly used equipment including card-readers and teletypes. The early use of computers by biologists for numerical taxonomy or phenetic clustering is well known, but in recent years a number of other exciting computer methods have been developed, many of which are noted by Ledley (1965), Crovello and MacDonald (1970), and Furlow et al. (in press). General information storage and retrieval systems for biological data are also being studied, such as the one being developed for the Flora North America Program (Shetler, in press). Although not computerized, other imaginative methods for publishing information have also appeared in recent years; several are mentioned by Leenhouts (1966) and Morse (in press). Modern information-processing technology allows convenient data exchange between researchers as well as the usual processing of one's own data, as discussed by Peters and Collette (1968). In some commercially available systems, a central computer serves the entire nation through a network of datacommunication links and a user can permit others access to his data and programs. These systems allow development of a centralized taxonomic data bank of data files prepared by the various workers in a project and released by their authors for general use. For effective utilization of such an information network, standardized machineindependent data formats are necessary. Preliminary data-sharing experiments between Michigan State University and the Smithsonian Institution and between the Smithsonian and the American Museum of Natural History have already shown the potential convenience and practicality of such a system. For those who would choose to use it, a standardized data format would offer several advantages over independent and individual preparation of taxonomic data for different computers and information systems. The standard format would make one investigator's data immediately available and comprehensible to all others using the same format. It would also make any information in the proper format available for one's own use without local modifications. Furthermore, a data standard facilities development of packages or libraries of programs for processing any data so encoded. Once written and tested, these routines could be used easily by others who had no knowledge of computer programming itself. Without the standard, they would have to modify the programs to accept their own data, or reformat the data for the programs, no easy task for a computer programmer, much less the average taxonomist. Early versions of the data format described here were, in fact, developed for use with program packages being prepared by the authors, and have also been used by others for numerical phenetics and for phyletic studies. A standard data format can also provide a basis for theoretical models of taxon and character concepts for various studies, as noted by Heywood (1968). Possibly ideas such as "unit character" and "polythetic taxon" could be expressed in terms of the data format, or vice versa, providing a common base for discussion of various algorithms and procedures. New theoretical results, in turn, could be incorporated rapidly into existing programs if xplicable in terms of the data base involved. Finally, standardization of the taxonomic data format for computer use would offer theoreticians an extensive base of biologically acceptable test data for checking new hypotheses. More complex formats, of course, may be needed for general taxonomic information-retrieval, and we fully recognize the need for a "background matrix" of detailed information to support the data summary presented in the matrix format.

Confidence Limits for System Reliability: A Sequential Method

Abstract: A sequential method is given for obtaining confidence limits for system reliability when ``pass-fail'' test data have been obtained on components. Costs of testing are examined and a rule is derived for determining the order in which to test the components so that the average cost of testing is minimized. The method is presented first for series systems, but in Section IV the extension to parallel systems is considered and in Section V the procedure is applied to a series-parallel configuration. Comparisons are given with fixed sample-size testing and it is shown that the sequential method is statistically efficient and that many of the difficulties encountered when using fixed sample sizes are eliminated by testing sequentially.

Comparison of experimental and theoretical results for the hydrostatic bulging of circular sheets

Abstract: Incremental and total-strain theories have recently been used by the authors to obtain numerical solutions for the hydrostatic bulging of circular diaphragms. These solutions have incorporated the effects of anisotropy in the direction of the thickness of the sheet. This investigation was conducted to obtain test data on aluminum-killed steel sheets which contain the above mentioned anisotropy and to compare these data with the predictions of the incremental and total-strain theories solutions. The results show that the incremental theory is in better agreement with test data than the total-strain theory. Strain-path data for several volume elements shows that each volume element follows an approximately proportional strain path. However, the strain paths obtained from the total-strain theory are in gross disagreement with the data.

Apparatus and method for testing a multi-terminal logic circuit capable of detecting fixed and intermittant faults

Abstract: A programmed test arrangement for electronic assemblies compares the output of an array (generally of integrated circuits) to be tested against either the output from another similar array or a model output. Circulating shift registers containing the test data provide a sequence of two state test signals. These test signals together with various unchanging signals are connected as inputs to the arrays. The registers are loaded in accordance with a program that is a function of the circuit being tested. Fixed and intermittent faults on the electrical arrangement under test are identified by particular patterns of fault indications generated responsive to the two state logic output signals. The test data cycled through the circulating registers is a function of the type of array to be tested. The fault indicated is a function of the error in the particular array being tested.

Multiwheel Landing Gear-Soils Interaction and Flotation Criteria - Phase 3, Part 1

Abstract: : The operational use of military aircraft in forward area situations has necessitated a comprehensive look at the critical factors which define the aircraft flotation performance and operations capability on semi- and unprepared soil runways. The investigation was directed primarily at defining the drag- sinkage response of multiple wheel landing gear on soil and the development of multiwheel flotation criteria to permit comparative evaluation of the relative merits of various landing gear configurations. The total multiwheel/soil interaction study consisted of four parts. Part 1 was an evaluation of existing full scale field test data from aircraft or test carts operating with multiple tire configurations (twin and tandem). The results of the study show that certain multiwheel configurations and spacing are beneficial in terms of sinkage-drag performance. The results of the multiwheel/soil interaction study were used to develop multiwheel flotation criteria (guidelines for evaluating performance). The flotation variable of braking was also studied on a preliminary basis. Braked tire/soil interaction equations suitable for defining the braking coefficient on soil were developed, and the results of a comparative study using these braked tire equations were favorable.

Outline of a Theory of Powerful Selection of Distribution Functions.

Abstract: : The conventional method of analyzing a given set of test data consists in assuming a distribution function and estimating its parameters. The only way of deciding whether the function is acceptable or not and which of two assumed functions is the better one is by means of a test of goodness-of-fit. For small and moderate sample sizes this test makes a very unreliable basis for a decision, and the confidence that can be put in the choice is practically unknown. In order to eliminate these deficiencies a new method, called the method of powerful selection, is proposed. By use of a test statistic, called the selector, it is possible, without preceding parameter estimations, to state the acceptability of a function on the basis of a preassigned level-of-significance and the decision power, that is, the chance of making a true decision between two functions. The tools of this method are presented and their applications illustrated by numerical analyses of some fatigue-test series. It will not too seldom occur that none of several assumed functions will be accepted. In this situation the selectors can be used for diagnosing the rejected functions with regard to causes such as outlying observations, composed populations, and contaminated data. (Author)

Engine/Inlet Compatibility Analysis Procedure

Abstract: New analysis and testing techniques have been developed during the past five years to identify and fix potential compatibility problems before flight. These techniques are described, and examples of compatibility data are given for a supersonic inlet and a turbofan engine. The engine/inlet interface is defined in terms of maximum time-variant distortion and time-averaged inlet pressure. Model inlet test data and engine component data are combined by dynamic simulation to audit compatibility and to identify components which need improvement. Compatibility audits also include the effects of control transients, component interactions, Reynolds number and engine-to-engine variations. Tests become more sophisticated as components become better developed. Engine testing with distortion simulated by simple inlet screens is replaced by more expensive but more realistic testing with an inlet simulator. Individual component testing evolves into dual-spool testing and engine testing. The final proof of compatibility requires combined inlet and engine testing. By this time, the data bank should contain sufficient knowledge to assist in quick identification and solution of any new problems.

Wind-Tunnel Investigation of a Quarter-Scale Two-Bladed High-Performance Rotor in a Freon Atmosphere

Abstract: : A joint USAAVLABS/NASA-Langley/Bell Helicopter Company experimental investigation of a quarter-scale two-bladed teetering rotor system was conducted in the NASA-Langley Transonic Dynamics Tunnel using Freon as a test medium. Rotors tested were a dynamically similar Bell 540 rotor having -10-degree twist, and a thin-tipped rotor having 0-degree twist. Aerodynamic and loads data were obtained at advance ratios from 0.30 to 0.72 in combination with advancing-tip Mach numbers varying from 0.70 to 0.96. These data were compared to full-scale data and theory. In general, the aerodynamic test data followed predicted trends and correlated well with full-scale tunnel data in the areas of low blade loading at low advance ratio and low advancing-tip Mach numbers. The blade loads data followed the expected trends, but their magnitudes could not be readily compared to existing flight test data due to the differences between the flight test conditions, model test conditions attained, and hub impedance differences. (Author)

Apollo telescope mount/thermal systems unit - Correlation of predicted data and test results

Abstract: ATM for manned solar observation, discussing thermal design, thermal vacuum test philosophy, mathematical models and analytical and test data correlation

Calibration apparatus and method for use with sweep rate test measurement equipment

Abstract: An apparatus used in conjunction with sweep rate test measurement equipment to normalize output data produced by the test equipment which includes a comparator that is responsive to correction data produced by the test equipment while the test equipment is coupled to a standard device having known parameters. A reference data signal is also applied to the comparator simultaneously with the correction data and the comparator produces difference signals representative of deviations in magnitude between the correction data and the reference data signals which are stored in shift registers at the sweep rate of the test equipment. The test equipment is subsequently coupled to prime equipment having unknown parameters for test measurement and the stored difference signals are combined with the test data from the prime equipment in a divider circuit which produces output test data that is normalized to the known parameters of the standard equipment.

Estimations on indirect tensile strengths for lime-treated materials

Abstract: WITHIN THE FRAMEWORK OF A RESEARCH EFFORT CONCERNED WITH THE EVALUATION OF TENSILE PROPERTIES OF STABILIZED SUBBASE MATERIALS, IT WAS DESIRED TO ESTABLISH A MEANS TO PREDICT INDIRECT TENSILE STRENGTH FROM TEXAS HIGHWAY DEPARTMENT TESTS FOR LIME-TREATED MATERIALS EXPERIMENTS WERE DESIGNED TO DEVELOP A PREDICTIVE EQUATION IN TERMS OF FACTORS INVOLVED WITH MIX DESIGN, CONSTRUCTION, AND CURING AND TO DETERMINE WHETHER ACCEPTABLE CORRELATIONS EXIST BETWEEN THE INDIRECT TENSILE TEST AND BOTH THE COHESIOMETER TEST AND THE UNCONFINED COMPRESSION TEST THESE CORRELATIONS WERE DEVELOPED BY USING 2 APPROACHES: THE FIRST VARIED 5 FACTORS (COMPACTIVE EFFORT, MOLDING WATER CONTENT, LIME CONTENT, CURING TEMPERATURE, AND CLAY CONTENT) AT 3 LEVELS EACH, AND THE SECOND, BASED ON TEXAS HIGHWAY DEPARTMENT TESTING PROCEDURES, VARIED ONLY MOLDING WATER CONTENT, LIME CONTENT, AND CLAY CONTENT BECAUSE CURING TEMPERATURE AND COMPACTIVE EFFORT ARE FIXED BY THE TEST SPECIFICATIONS IT WAS FOUND THAT ACCEPTABLE CORRELATIONS FOR LIME-TREATED MATERIALS EXIST FOR BOTH APPROACHES BETWEEN THE INDIRECT TENSILE TEST AND COHESIOMETER TEST, THE INDIRECT TENSILE TEST AND UNCONFINED COMPRESSION TEST, AND THE INDIRECT TENSILE TEST AND THE COMBINED RESULTS OF THE COHESIOMETER AND UNCONFINED COMPRESSIVE TEST THESE CORRELATIONS PROVIDE THE CAPABILITY OF ESTIMATING THE INDIRECT TENSILE STRENGTH FROM THE COHESIOMETER OR THE UNCONFINED COMPRESSION TEST DATA OR BOTH FOR LIME-TREATED MATERIALS USED IN PAVEMENTS NOW IN SERVICE /AUTHOR/

Atmospheric Model Evaluation.

Abstract: : The report documents a computer program which has been developed for testing and evaluating atmospheric models. The present version of the program contains ten such models which have been evaluated using a variety of staellite orbits as test data. An important feature of the program is an ephemeris generator which requires considerably less computer time than a standard numerical integration technique. This procedure is documented in Appendix B. Complete instructions for running the program are given in Appendix A, and a description of the ten atmospheric models presently contained in the program may be found in Appendix C. (Author)

RUDI: A Computer-Controlled Test-Data-Acquisition and Processing System

Abstract: A data-acquisition system built around a multiprogrammed SEL-810A digital computer is used by the RCA-Astro-Electronics Division (AED) Environmental Test Center, Princeton, N. J., for the acquisition and processing of quasi-static signals originating from a variety of analog transducers during spacecraft environmental simulation tests. The system gathers analog data with the aid of three mobile instrumentation carts located at the test site and generates data logs for both magnetic tape and hardcopy printout. Because of the slowly varying data, high scan rates were of no particular importance; instead, prime targets were assurance of data integrity, speedy setup operations, accomodation of a large variety of transducers, and order and flexibility in data presentation. System accuracy excluding transducers is 0.25 percent of full scale (FS). Measurement results obtained at 200 channels/s are presented in selectable formats primarily on a line printer directly in engineering units. Three unrelated test activities can be accommodated simultaneously without mutual dependence or interference and a total of 750 channels can be processed. Setup information, test directives, and real-time test monitoring are handled with the aid of interactive communications in English memonics.

Transient analysis of a viscoelastic torsion pendulum: Error analysis

Abstract: The error analysis for the transient torsion pendulum test is developed based on a linearized approximation. Tables are given for the efficient utilization of the equations in evaluating the accuracy range of the test data.

Effects of Mass Additions on Viscous Flow Parameters

Abstract: : The objective of the effort is to re-evaluate the influential mechanisms of interaction between re-entry body heat shield ablation and aerodynamic parameters, based upon data obtained under the preceding STREET-G contract, other ground test data, with analytic results, and with applicable flight test data. The specific objectives of this research are to improve (1) the empirical correlations which account for mass injection effects on the viscous layer thicknesses, (2) the basic turbulent relations for predicting the viscous properties, and (3) the validity of the Crocco integral for turbulent flows with mass injection. The influence of the improved correlations on the vehicle drag for some typical flight vehicles is also ascertained.

Dynamic testing of a single-degree-of-freedom strapdown gyroscope

Abstract: Test methods and results are presented for the equivalent average input rate of a single-degree-of-freedom gyroscope operated both open loop and with a ternary-logic pulse-torque-to-balance loop during multiaxis angular oscillation. For the open-loop tests, good agreement was obtained with theoretical results. Two-axis testing was performed for oscillations about the Input-Output axes, the Input-Spin axes, and the Spin-Output axes. These tests run in the torque-to-balance mode revealed significant departures from open-loop results in the induced drift rate. An analysis is developed explaining much of the closed-loop data presented. Test data for the gryoscope in a ternary torque-to-balance loop with constant input rates is presented. The tests demonstrate that the instrument rate linearity does not change with interrogation frequency from 3,600 to 14,400 Hz if the torque coil is tuned to offer a resistive load to the current switch. Analysis cited shows that gyroscope lag compensation eliminates multiple pulsing and other equivalent forms of degraded resolution in a wide variety of quantizing loops. This result is test verified for the ternary delta-modulator loop.

Determination Of Bottom Breakout For Deep Submergence Vehicle Safety

Abstract: There has been only one known test to date which has produced accurate data on submersible craft overcoming bottom suction. This paper proposes a method for calculating breakout force, based on test data. A relative index is then presented as a means of comparing the breakout capability of various craft now in operation and as a guide to designers of submersible vehicles.

Investigation of soil damping on full-scale test piles

Abstract: THIS INVESTIGATION WAS CONDUCTED DURING THE FOURTH YEAR OF A FIVE-YEAR STUDY ON "BEARING CAPACITY FOR AXIALLY LOADED PILES" THE APPLICABILITY OF TWO DIFFERENT MATHEMATICAL MODELS WHICH DESCRIBE SOIL DAMPING CHARACTERISTICS IS EVALUATED FOR USE IN WAVE EQUATION ANALYSES OF PILING BEHAVIOR A WAVE EQUATION COMPUTER PROGRAM IS USED TO PREDICT PILE BEARING CAPACITY AND THE PREDICTED CAPACITY IS COMPARED WITH FIELD LOAD TEST DATA FROM FULL-SCALE TEST PILES WAVE EQUATION ANALYSES OF FOUR FULL-SCALE TEST PILES EMBEDDED ENTIRELY IN HIGHLY PLASTIC CLAY SOILS INDICATE THAT AN AVERAGE VALUE OF J' = 02 SEC/FT FOR THE FRICTION DAMPING AND A POINT DAMPING PARAMETER OF J = 015 SEC/FT MAY BE USED WITH THE MATHEMATICAL MODEL HAVING A VELOCITY EXPONENT V OF 10 TWO ADDITIONAL TEST SITES ARE ANALYZED WHERE THE TEST PILES WERE EMBEDDED PREDOMINANTLY IN A HIGHLY PLASTIC CLAY, BUT THE PILE TIPS WERE EMBEDDED IN SAND WHEN THE MATHEMATICAL MODEL WITH V = 10 AND J = 015 IS USED, EXTREMELY HIGH VALUES OF FRICTION DAMPING ARE NEEDED TO ACHIEVE AGREEMENT BETWEEN PREDICTED AND ACTUAL BEARING CAPACITY HOWEVER, WHEN J' = 02, POINT DAMPING VALUES OF 095 AND 155 SEC/FT ARE OBTAINED THE ANALYSIS OF THESE TWO TEST PILES WITH TIPS EMBEDDED IN SAND INDICATES THAT A J VALUE MUCH GREATER THAN 015 IS REQUIRED FOR AGREEMENT BETWEEN PREDICTED AND ACTUAL BEARING CAPACITY HOWEVER, ADDITIONAL TEST DATA ARE NEEDED TO VERIFY THIS TREND /AUTHOR/