On Minimum Fuel and Energy Control of Sampled- Data Control Systems Scientific Report No. 12
Nonlinear control of pulse amplitude modulated sampled-data systems
SAMPLED DATA SYSTEM↗
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High resolution data processing for PFM TELEMETRY.
Data processing of PFM telemetry whereby resolution of frequency measurements is dependent upon SNR, for application to satellite parameters
TELEMETRY↗
A calibration means for spectrum analyzers
Spectrum analyzer calibration system is rapid and provides an accurate family of adjustable markers at any point in the spectrum. Pulse width controls determine the number of markers. The unit operates with a repetition rate from 300 cps to 40 kc at a center frequency from 10 kc to 2 Mc.
Larson, M. S.↗
Remotely-actuated biomedical switch
Remotely-actuated biomedical switching circuit using transistors consumes no power in the off position and can be actuated by a single-frequency telemetry pulse to control implanted instrumentation. Silicon controlled rectifiers permit the circuit design which imposes zero drain on supply batteries when not in use.
Lee, R. D.↗
Magnetically coupled emission regulator
Magnetic coupling between input and power handling circuits isolates high voltage. A feedback regulator samples the ion source bias current and provides deviation signals to a magnetic amplifier pulse modulator. The pulse modulator controls the dc to ac power inverter which in turn, controls the emission current.
Source record↗
Pulse motor for spacecraft attitude control.
Multipulse thruster module design and development tests for spacecraft attitude control, noting micropulse solid propellant rocket motor
Blackwood, D.↗
Development of a continuous linear model of a d-c to d-c flyback converter.
The analytical design of the feedback circuit for a d-c flyback converter requires the formulation of a model defining the static and dynamic performance of the forward loop. This paper describes the steps which were taken to develop a linear continuous model of a typical flyback circuit. Although the method uses several approximations to simplify the work, the resulting model was found to duplicate the performance of the actual circuit very closely. The model makes it possible to design the feedback circuit using well known linear feedback techniques. The method is an extension of prior work in the modeling of pulse-width controlled circuits.
Wells, B. A.↗
Nondestructive and impulsive testing of electroexplosive devices.
Discussion of NDT techniques and instrumentation developed to demonstrate the quality and normal behavior of 1-W/1-A no-fire electroexplosive devices (EEDs) without firing or degrading the units. Application of these techniques is limited to the bridgewire/explosive/header interface which is considered to be the most critical link in the electroexplosive chain. A certain amount of destructive testing required to determine the sensitivity and output of the EEDs can be accomplished by additional instrumentation that initiates and delivers energy in an impulsive manner with control of pulse width and amplitude.
Menichelli, V. J.↗
Development and planning and design of equipment pumping generator of semiconductor lasers
The schematic of a multidimensional current pulse generator is studied. A MTKh-90 cold cathode thyratron is used as the current commutator. In the autooscillation mode on a frequency of 380 hertz the generator creates a current to 100 amps per pulse in a control resistance of 1 ohm. The pulse duration is regulated within the limits from 0.1 to 3.0 microseconds.
Popkov, A. V.↗
Electric vehicle power train instrumentation: Some constraints and considerations
The application of pulse modulation control (choppers) to dc motors creates unique instrumentation problems. In particular, the high harmonic components contained in the current waveforms require frequency response accommodations not normally considered in dc instrumentation. In addition to current sensing, accurate power measurement requires not only adequate frequency response but must also address phase errors caused by the finite bandwidths and component characteristics involved. The implications of these problems are assessed.
Triner, J. E.↗
Electric vehicle power train instrumentation - Some constraints and considerations
The application of pulse modulation control (choppers) to dc motors creates unique instrumentation problems. In particular, the high-harmonic components contained in the current waveforms require frequency-response accommodations not normally considered in dc instrumentation. In addition to current sensing, accurate power measurement not only requires adequate frequency response but also must address phase errors caused by the finite bandwidths and component characteristics involved. This paper discusses the implications of these problems and reports on the degree to which they have been solved at Lewis Research Center.
Triner, J. E.↗
Solar-Cell-Junction Processing System
System under development reduces equipment costs. Processing system will produce solar-cell junctions on 4 in. (10.2 cm) round silicon wafers at rate of 10 to seventh power per year. System includes non-mass-analyzed ion implanter, microcomputer-controlled, pulsed-electron-beam annealer, and wafertransport system with vacuum interlock. These features eliminate large, expensive magnet and plates, circuitry, and power source otherwise needed for scanning.
Bunker, S. N.↗
Power Electronics for a Miniaturized Arcjet
A 0.3 kW Power Processing Unit (PPU) was designed, tested on resistive loads, and then integrated with a miniaturized arcjet. The main goal of the design was to minimize size and mass while maintaining reasonable efficiency. In order to obtain the desired reductions in mass, simple topologies and control methods were considered. The PPU design incorporates a 50 kHz, current-mode-control, pulse-width-modulated (PWM), push-pull topology. An input voltage of 28 +/- 4V was chosen for compatibility with typical unregulated low voltage busses anticipated for smallsats. An efficiency of 0.90 under nominal operating conditions was obtained. The component mass of the PPU was 0.475 kg and could be improved by optimization of the output filter design. The estimated mass for a flight PPU based on this design is less than a kilogram.
Pinero, Luis R.↗
Museum Exhibit
A TSP from NASA Tech Briefs provided the solution to an electrical problem at a Florida museum. When a model train would not start without a jerk, a Marshall Space Flight Center development called pulse width control was adapted. The new circuit enables the train to start smoothly and reduces construction and maintenance costs. The same technology is also used in another hands-on exhibit. Applications of other TSPs are anticipated.
Source record↗
A Wind Tunnel Model to Explore Unsteady Circulation Control for General Aviation Applications
Circulation Control airfoils have been demonstrated to provide substantial improvements in lift over conventional airfoils. The General Aviation Circular Control model is an attempt to address some of the concerns of this technique. The primary focus is to substantially reduce the amount of air mass flow by implementing unsteady flow. This paper describes a wind tunnel model that implements unsteady circulation control by pulsing internal pneumatic valves and details some preliminary results from the first test entry.
Cagle, Christopher M.↗
Flow Control on Low-Pressure Turbine Airfoils Using Vortex Generator Jets
Motivation - Higher loading on Low-Pressure Turbine (LPT) airfoils: Reduce airfoil count, weight, cost. Increase efficiency, and Limited by suction side separation. Growing understanding of transition, separation, wake effects: Improved models. Take advantage of wakes. Higher lift airfoils in use. Further loading increases may require flow control: Passive: trips, dimples, etc. Active: plasma actuators, vortex generator jets (VGJs). Can increased loading offset higher losses on high lift airfoils. Objectives: Advance knowledge of boundary layer separation and transition under LPT conditions. Demonstrate, improve understanding of separation control with pulsed VGJs. Produce detailed experimental data base. Test and develop computational models.
Volino, Ralph J.↗
Pulsed ultrasonic stir welding method
A method of performing ultrasonic stir welding uses a welding head assembly to include a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. In the method, the rod is rotated about its longitudinal axis during a welding operation. During the welding operation, a series of on-off ultrasonic pulses are applied to the rod such that they propagate parallel to the rod's longitudinal axis. At least a pulse rate associated with the on-off ultrasonic pulses is controlled.
Ding, R. Jeffrey↗
Investigating Radiation-Induced Actinide Species in Solution
Our fundamental understanding of actinide radiation-induced redox chemistry is crucial to nuclear fuel cycle development, due to the unavoidable exposure of these elements to ionizing radiation fields, both inherent and from in-process applications. Plutonium (Pu) and americium (Am) both possess multiple oxidation states, the careful manipulation of which are essential in the study and utilization of their rich chemistry, developing new nuclear technologies, and securing the long-term sustainability of nuclear power. However, knowledge in this area is far from complete. Consequently, we have studied the radiation-induced chemistry of both Pu and Am through a variety of techniques. Temperature-controlled electron pulse radiolysis has been used to study Am for the first time, determining the feasibility of Am redox reactions under used nuclear fuel reprocessing conditions, (e.g. nitric acid, non-ambient temperature). Additionally, we have developed an experimentally evaluated multi-scale computer model for the prediction of gamma radiation-induced Pu redox chemistry due to radiolysis and disproportionation reactions in concentrated nitric acid solutions.
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗