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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Development of Temperature Compensation Tools for SPNDs Operating in High Temperature Environments

Two rhodium-based self-powered neutron detectors (Rh-SPNDs) were irradiated at the Massachusetts Institute of Technology Reactor as a follow-on experiment to the heated irradiation previously conducted at the Neutron Radiography facility at Idaho National Laboratory. The experiment was conducted over the temperature ranges of 600-850°C to further examine the effects of temperature on the Rh-SPNDs. Four tests of varying temperature and power were performed. The tests identified two types of temperature effects consistent with historical evaluations. One effect is a prompt proportionality to temperature at steady-state reactor power due to the decrease in Rh-SPND insulation resistance. The other effect is a delayed effect generated from displacement currents generated by changing the space charge within the insulator as a function of temperature. The result of this experiment demonstrates a characterizable responses to temperature that is feasible for developing a temperature compensation tool for SPND operating in high temperatures. The characteristics identified in this experiment will be integrated within the delayed-response compensation techniques for FY23 evaluation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Demonstration of Temperature Compensation Techniques for SPNDs Operating in High Temperatures

This report presents the testing results of rhodium-based self-powered neutron detectors (Rh-SPND) irradiated in a furnace dry tube from ambient temperature to 850°C at the Ohio State University Research Reactor. The purpose of the experiment is to demonstrate the technique and application of a temperature compensation technique for the Rh-SPND. This is performed by characterizing the temperature effects observed in past experiments—a displacement current and a stabilized dark current—of the Rh-SPND as a function of temperature under the models of shifting space charges as a product of photoconductivity properties. Low-power irradiation at the OSURR was performed with stabilized temperatures of ambient, 550, 575, 600, 625, 650, 675, and 700°C were first performed to obtain the curve fit parameters that describes the temperature effects. The results provided further insight for the behavior of the SPND at high temperatures in accordance with available insulation conductivity models. Transition points from photoconductivity to ionic conductivity were identified in the range of 550–600°C. Additionally, transition points ionic to electric conductivity were observed in the range of 675–700°C, however, the data was not able to fully capture the transition and did not have enough resolution to provide predictive compensation based only on temperature readings.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

A reactive ferroelectric tuner for microphonics compensation

Jefferson Lab (JLab) is actively pursuing an extensive research program focused on developing advanced Nb₃Sn superconducting technology for particle accel-eration. Due to the brittle nature of Nb₃Sn coatings, a Ferroelectric Tuner (FRT) currently represents the most viable approach for microphonics compensation in these next-generation cavities. We suggest a novel, fast-responding FRT integrated directly into the main coupler, eliminating the need for an additional RF port. Leveraging a unique RF design based on a magic-T configuration, this advanced FRT will enable micro-phonics compensation in the ±30 Hz range without undesirable changes to the external quality factor.

Accelerator Physics↗
NASA NTRS1965

Detector circuit compensates for vidicon beam current variations

Signal detector circuit compensates for black level shifts in vidicons by dark current cancellation. It clamps the video signal to the dark current component of the signal. The device also compensates for background noise variation or transducer bias fluctuations in other repetitive pulse systems.

Source record↗
NASA NTRS1970

Error compensation for hybrid-computer solution of linear differential equations

Z-transform technique compensates for digital transport delay and digital-to-analog hold. Method determines best values for compensation constants in multi-step and Taylor series projections. Technique also provides hybrid-calculation error compared to continuous exact solution, plus system stability properties.

Kemp, N. H.↗
NASA NTRS1971

Compensator improvement for a large space vehicle.

This paper presents the theory and a technique for compensator improvement. Several definitions in regard to relative stability are presented along with some frequency response limitations and characteristics of a large space vehicle. A nonlinear programming algorithm for obtaining an improved solution for a strict constraint problem is developed and the necessary partial derivatives for applying the algorithm to compensator improvement are derived. Finally, for illustrating the effectiveness of the algorithm, the frequency response of a large space vehicle is improved.

Mitchell, J. R.↗
NASA NTRS1973

Motion compensator for holographic motion picture camera

When reference beam strikes target it undergoes Doppler shift dependent upon target velocity. To compensate, object beam is first reflected from rotating cylinder that revolves in direction opposite to target but at same speed. When beam strikes target it is returned to original frequency and is in phase with reference beam. Alternatively this motion compensator may act on reference beam.

Kurtz, R. L.↗
NASA NTRS1972

Magnitude error bounds for sampled-data frequency response obtained from the truncation of an infinite series, and compensator improvement program

The frequency response method of analyzing control system performance is discussed, and the difficulty of obtaining the sampled frequency response of the continuous system is considered. An upper bound magnitude error equation is obtained which yields reasonable estimates of the actual error. Finalization of the compensator improvement program is also reported, and the program was used to design compensators for Saturn 5/S1-C dry workshop and Saturn 5/S1-C Skylab.

Mitchell, J. R.↗
NASA NTRS1973

Design and analysis of a star image motion compensator

The feasibility of designing and fabricating a small optical system to compensate for motions of a stellar field image on the focal plane of a large orbiting telescope is examined for a single-axis system. An all-reflecting two-mirror star image motion compensator maintains both a flat focal plane and image focus for one or more star images. Both theoretical and experimental evaluations show that only one adjustment is needed to aline the system since the change in focus is linearly related to the misalinements of all critical components. Results of an error analysis show that the focus error resulting from fabrication tolerances is very small compared to the adjustment capability of the system.

Romanczyk, K. C.↗
NASA NTRS1973

Compensation of vibrations of a unidimensional structure and a plane acoustical field

Endless structures are realized in practice, in the presence of loss and to an adequate extent, owing to which, reflections from the edges to the center part of the structure can be disregarded. In the absence of losses, reflections from the boundary frequently have to be taken into account. In this case, besides compensation for waves passing through the boundary, the reciprocal connection system can be used for compensation of the total field ahead of the boundary. In these cases, the system converters can be located in a different manner relative to the boundary and to one another. Each of the locations has inherent peculiarities, which must be taken into account in solving specific problems.

Tartakovskiy, B. D.↗
NASA NTRS1974

Analysis and compensation of an aircraft simulator control loading system with compliant linkage

A hydraulic control loading system for aircraft simulation was analyzed to find the causes of undesirable low frequency oscillations and loading effects in the output. The hypothesis of mechanical compliance in the control linkage was substantiated by comparing the behavior of a mathematical model of the system with previously obtained experimental data. A compensation scheme based on the minimum integral of the squared difference between desired and actual output was shown to be effective in reducing the undesirable output effects. The structure of the proposed compensation was computed by use of a dynamic programing algorithm and a linear state space model of the fixed elements in the system.

Johnson, P. R.↗
NASA NTRS1975

A study of digital gyro compensation loops

The feasibility is discussed of replacing existing state-of-the-art analog gyro compensation loops with digital computations. This was accomplished by designing appropriate compensation loops for the dry turned TDF gyro, selecting appropriate data conversion and processing techniques and algorithms, and breadboarding the design for laboratory evaluation. A breadboard design was established in which one axis of a Teledyne turned-gimbal TDF gyro was caged digitally while the other was caged using conventional analog electronics. The digital loop was designed analytically to closely resemble the analog loop in performance. The breadboard was subjected to various static and dynamic tests in order to establish the relative stability characteristics and frequency responses of the digital and analog loops. Several variations of the digital loop configuration were evaluated. The results were favorable.

Source record↗
NASA NTRS1975

Limitation on the use of the horizontal clinostat as a gravity compensator

If the horizontal clinostat effectively compensates for the influence of the gravity vector on the rotating plant, it makes the plant unresponsive to whatever chronic acceleration may be applied transverse to the axis of clinostat rotation. This was tested by centrifuging plants while they were growing on clinostats. For a number of morphological endpoints of development, the results depended on the magnitude of the applied g-force. Gravity compensation by the clinostat was incomplete, and this conclusion is in agreement with results of satellite experiments which are reviewed.

Brown, A. H.↗
NASA NTRS1976

Polarization compensator for optical communications

An optical data communication system is provided whereby two orthogonal polarization states of a light beam carrier correspond to digital states. In such a system, automatic polarization compensation is provided by applying a dither modulating voltage to a cell exhibiting the electro-optic effect. The cell controls the relative phase of electric field components of an input light beam enabling the dither frequency component of the difference of the instantaneous powers in the two polarization states to be coherently detected. A signal derived from the coherent detection process is fed back to the cell via an integrator to form polarization bias compensating servo loop ot Type 1.

Fitzmaurice, M. W.↗
NASA NTRS1976

Limitation on the use of the horizontal clinostat as a gravity compensator

If the horizontal clinostat effectively compensates for the influence of the gravity vector on the rotating plant, it should make the plant unresponsive to whatever chronic acceleration may be applied transverse to the axis of clinostat rotation. This was tested by centrifuging plants while they were growing on clinostats. For a number of morphological endpoints of development the results depended on the magnitude of the applied g-force. Therefore, gravity compensation by the clinostat was incomplete. This conclusion is in agreement with results of satellite experiments which are reviewed.

Brown, A. H.↗
NASA NTRS1977

Compensated time of flight telescope for spaceborne cosmic ray measurements

A large area time-of-flight telescope has been studied for future application in space-borne cosmic ray experiments. A new compensation technique for propagation delays inside the scintillators has been applied, which is operative in two perpendicular directions. This technique, superior to conventional one-dimensional compensations, allows high rejection probability for upward moving single particles at very short counter distances. Besides mechanical advantages a short counter distance is desirable because it permits a large field of view for the detector. A measurement of light transit times in scintillators is presented and based on it, directionality for shower events is discussed.

Rothermel, H.↗
NASA NTRS1978

The discrete-time compensated Kalman filter

A suboptimal dynamic compensator to be used in conjunction with the ordinary discrete time Kalman filter was derived. The resultant compensated Kalman Filter has the property that steady state bias estimation errors, resulting from modelling errors, were eliminated.

Lee, W. H.↗
NASA NTRS1977

Frequency domain compensation of a DYNGEN turbofan engine model

Following Rosenbrock's ideas regarding the advantages of dominance in linear multivariable control systems, a new graphical technique is used for the design of compensators that achieve dominance. The technique is illustrated with an application to the problem of designing compensators for a linear turbofan-engine model. The resulting design is put into perspective by examining it in the light of two other multivariable frequency-domain methods. One, MacFarlane's method of characteristic loci, is used to realize a final design for stability and low interaction. The other is a direct technique based upon the algebraic expansion of the determinant of the return difference in terms of it's elements. Results from simulations carried out on the NASA DYNGEN software are included.

Schafer, R. M.↗