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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Protection - Principles and practice.

The protection mechanisms of computer systems control the access to objects, especially information objects. The principles of protection system design are formalized as a model (theory) of protection. Each process has a unique identification number which is attached by the system to each access attempted by the process. Details of system implementation are discussed, taking into account the storing of the access matrix, aspects of efficiency, and the selection of subjects and objects. Two systems which have protection features incorporating all the elements of the model are described.

Graham, G. S.↗
NASA NTRS1973

The state space and transfer function approaches in practical linear multivariable systems design.

A procedure using transfer function formalism for stabilizing a multivariable feedback system with significant plant uncertainty is presented. The method shapes nominal loop functions and decreases their magnitudes with frequency in such a manner that the system remains stable throughout the plant uncertainty range. An example illustrates the application of the described procedure.

Shaked, U.↗
NASA NTRS1973

Non-classical adhesive-bonded joints in practical aerospace construction

Solutions are derived for adhesive-bonded joints of non-classical geometries. Particular attention is given to bonded doublers and to selective reinforcement by unidirectional composites. Non-dimensionalized charts are presented for the efficiency limit imposed on the skin as the result of the eccentricity in the load path through the doubler. It is desirable to employ a relativly large doubler to minimize the effective eccentricity in the load path. The transfer stresses associated with selective reinforcement of metal structures by advanced composites are analyzed. Reinforcement of bolt holes in composites by bonded metal doublers is covered quantitatively. Also included is the adhesive joint analysis for shear flow in a multi-cell torque box, in which the bond on one angle becomes more critical sooner than those on the others, thereby restricting the strength to less than the total of each maximum strength when acting alone. Adhesive plasticity and adherend stiffness and thermal imbalances are included. A simple analysis/design technique of solution in terms of upper and lower bounds on an all-plastic adhesive analysis is introduced.

Hart-Smith, L. J.↗
NASA NTRS1974

A practical scheme for adaptive aircraft flight control systems

A flight control system design is presented, that can be implemented by analog hardware, to be used to control an aircraft with uncertain parameters. The design is based upon the use of modern control theory. The ideas are illustrated by considering control of STOL longitudinal dynamics.

Athans, M.↗
NASA NTRS1974

The application of space technology to practical problems such as those currently facing the mountain sections of the State of Colorado

Rapid growth in small Colorado mountain communities and dangers posed by development in areas that are potentially dangerous to life and property due to natural processes are studied. Special attention was given to snow avalanche, mudflow, rockfall, landslide and flood, as well as the slow continuous and frequently imperceptible form of soil creep and associated mass movement. Data are also given on the relative reliability of ERTS and Skylab imagery and conventional photography in identifying avalanche paths and run out zones.

Ives, J. D.↗
NASA NTRS1974

Some practical examples of cavitation erosion and their prevention

The problem of failures caused by cavitation erosion are discussed. The concepts of intensity of erosion, erosion strength, and the time dependence of erosion rate are analyzed. The relation of these parameters to system variables such as pressure and velocity, and to the properties of materials are investigated. Using several examples of actual cavitation erosion, methods of prevention and their limitations are examined.

Conn, A. F.↗
NASA NTRS1974

Notes on the concept of normal values employed in clinical practice

The question of the considerable variations in various blood parameters under the influence of changes in environmental factors is discussed. Recommendations are given that so-called normal values should be given special attention. Fibrinolytic and fibrinogenolytic activity studies on the blood in healthy human beings revealed significant differences for individual months and even on specific days. Changes in the activity of fibrinolysis and fibrinogenolysis show a correlation with changes in the meteorological conditions, seasonal variations and changes in solar activity.

Platonova, A. T.↗
NASA NTRS1974

Method of magnetobiological indication in clinical laboratory practice

Data are presented on the use of the method of magnetobiological indication for defining the immunobiological state of patients with very serious diseases. It has been found that the enzymes of a patient react more sensitively to the energy from a magnetic field. It is important that the magnetoreactivity of the enzymes, like the cell forms of the blood in the patients, have a certain relationship to the clinical-nosological forms and the dynamics of the illness of the subject.

Sosunov, A. V.↗
NASA NTRS1974

Recommended practices for encapsulating high voltage assemblies

Preparation and encapsulation of high voltage assemblies are considered. Related problems in encapsulating are brought out in these instructions. A test sampling of four frequently used encapsulating compounds is shown in table form. The purpose of this table is to give a general idea of the working time available and the size of the container required for mixing and de-aerating.

Tankisley, E. W.↗
NASA NTRS1974

NASA CR-2120 - Summary of nondestructive testing theory and practice

This is a familiarization report of nondestructive testing (ndt) prepared by staff of the Battelle Columbus Laboratories on a NASA contract. There is a short introduction, a chapter on applicability of ndt which is illustrated with examples of typical defects and includes tables comparing the characteristics, interrelationships, and costs of the different techniques. There are chapters dealing with penetrants, magnetic particle radiography, ultrasonics, and eddy currents. New techniques are described.

Meister, R. P.↗
NASA NTRS1974

A practical obstacle detection system for the Mars Rover

Discussion of an obstacle detection system which uses a laser range finder as the principal sensing device. The laser scans the scene ahead and stores the range data for the terrain in a matrix form. This matrix can be thought of as a 'range image'. This range varies from point to point, but sharp changes are caused by the presence of obstacles. Some existing algorithms and one developed by the authors were used to obtain the outlines of obstacles from the 'range image'. All these algorithms end with a thresholding operation. A theoretical analysis shows how a proper value of the threshold may be chosen, given the type of irregularity of the terrain to be detected. The analysis also shows how large the statistics of measurement noise can be allowed without leading to false alarms.

Reed, M.↗
NASA NTRS1975

A practical multi-spectrum Hadamard Transform Spectrometer

A Hadamard Transform Spectrometer (HTS) which simultaneously obtains fifteen infrared spectra, each having 255 spectral elements was constructed. Spectra are obtained essentially in real time through use of a minicomputer with 8K words of memory and a CRT display. This permits operation of the instrument in the field.

Tai, M. H.↗