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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 1,045 records · Page 58

All sources NASA NTRS DOE OSTI

NASA NTRS1985

Method and apparatus for I-V data acquisition from solar cells

A method and apparatus for logging current-voltage (I-V) characteristic d of a solar cell module (10) in two modes using a portable instrument. One mode controls the load current through a circuit (36) in 256 equal intervals while voltage is measured from open circuit to at least halfway into the knee of the curve and the other mode controls the load voltage through a circuit (34) in 256 equal intervals from the lowest voltage measurement possible (short circuit) to at least halfway into the knee of the curve, under control of a microcomputer (12). All measurements are packed by discarding each measurement that is within 0.5% of the value predicted from two previous measurements, except every ninth (9th) measurement which is retained. The remaining data is further packed into a memory block of a detachable storage medium (14) by recording the data points in sequence following a header containing data common to all points, with each point having the value of the controlled parameter recorded as the number of increments from the previous point recorded followed by the measured value. The detachable storage medium is preferably a solid state device for reliability, and is transferable to a playback terminal which unpacks the data for analysis and display.

Cole, Steven W.↗

DOE OSTI2015

Long-pulse production of high current negative ion beam by using actively temperature controlled plasma grid for JT-60SA negative ion source

The temperature control system of the large-size plasma grid has been developed to realize the long pulse production of high-current negative ions for JT-60SA. By using this prototype system for the JT-60SA ion source, 15 A negative ions has been sustained for 100 s for the first time, which is three times longer than that obtained in JT-60U. In this system, a high-temperature fluorinated fluid with a high boiling point of 270 degree Celsius is circulated in the cooling channels of the plasma grids (PG) where a cesium (Cs) coverage is formed to enhance the negative ion production. Because the PG temperature control had been applied to only 10% of the extraction area previously, the prototype PG with the full extraction area (110 cm × 45 cm) was developed to increase the negative ion current in this time. In the preliminary results of long pulse productions of high-current negative ions at a Cs conditioning phase, the negative ion production was gradually degraded in the last half of 100 s pulse where the temperature of an arc chamber wall was not saturated. From the spectroscopic measurements, it was found that the Cs flux released from the wall might affect to the negative ion production, which implied the wall temperature should be kept low to control the Cs flux to the PG for the long-pulse high-current production. The obtained results of long-pulse production and the PG temperature control method contributes the design of the ITER ion source.

43 PARTICLE ACCELERATORS↗

NASA NTRS1984

Development of a DC propulsion system for an electric vehicle

The suitability of the Eaton automatically shifted mechanical transaxle concept for use in a near-term dc powered electric vehicle is evaluated. A prototype dc propulsion system for a passenger electric vehicle was designed, fabricated, tested, installed in a modified Mercury Lynx vehicle and track tested at the contractor's site. The system consisted of a two-axis, three-speed, automatically-shifted mechanical transaxle, 15.2 Kw rated, separately excited traction motor, and a transistorized motor controller with a single chopper providing limited armature current below motor base speed and full range field control above base speed at up to twice rated motor current. The controller utilized a microprocessor to perform motor and vehicle speed monitoring and shift sequencing by means of solenoids applying hydraulic pressure to the transaxle clutches. Bench dynamometer and track testing was performed. Track testing showed best system efficiency for steady-state cruising speeds of 65-80 Km/Hz (40-50 mph). Test results include acceleration, steady speed and SAE J227A/D cycle energy consumption, braking tests and coast down to characterize the vehicle road load.

Kelledes, W. L.↗

NASA NTRS2016

Integrated System for Health Management and Autonomous Control (ISHM-AC): Development and Application

Autonomous control systems represent a technological barrier from manual and automated operated control systems in an industry wide application. An increase in energy-efficient storage, transfer and use of cryogens and cryogenic propellants on Earth and in space has been observed in space related industries between NASA, government and commercial programs. An increase in efficiency of cryogenic systems demands an increase in the capabilities of the control and monitoring system that manages them. As new technologies are developed for cryogenic systems, complexity and capability increases. The increase in complexities are a natural drive to develop better and more capable health monitoring and control system management. Current research and development efforts lead the Cryogenics Test Laboratory at the Kennedy Space Center to improve its automated control and health monitoring system from a Programmable Logic Control (PLC) based-only system to a fully Integrated System for Health Management (ISHM) - Autonomous Control (AC) capable of performing autonomous operations on a cryogenic propellant transfer system. This ISHM-AC system has been developed and tested by controlling a complete simulated propellant transfer operation. The capabilities and test results of this fully integrated autonomous system for cryogenics propellant transfer operation will be presented in this paper.

Toro, Jaime A.↗

NASA NTRS2016

Integrated System for Health Management and Autonomous Control (ISHM-AC) for Cryogenic Operations on the Simulated Propellant Loading System

Toro Medina, Jaime A.↗

NASA NTRS2018

Electric Motor Noise from Small Quadcopters: Part II - Source Characteristics

The increased interest in electric motors for aircraft propulsion systems has driven interest in quantifying the contribution of electric motor noise to the overall sound levels and possibly human annoyance of the propulsion system. This work presents acoustic measurements of electric motors used for small quadcopters to quantify the sound produced by a number of outrunner motors with different types of controllers. Results are presented for loaded and unloaded motors as well as installed and uninstalled configurations. Motor resonance frequencies were measured and computed. Current probe measurements showed significant harmonic content in the supply current from the controllers for both the conventional and sinewave controllers. Acoustic results showed motor noise is typically radiated at frequencies near that for azimuthal vibration mode number 2 of the rotor which occurs at roughly 5000 Hz. Electric motor noise was evident in the spectra produced by many of the motor-controller combinations for motors loaded with propellers with levels often greater than those for the motor alone due to increases in the stator magnetic flux density with increased current. An installed quadcopter configuration produced increases in acoustic radiation over that of the uninstalled motor in a frequency range near the 1200 Hz azimuthal vibration mode 1 of the rotor.

Henderson, Brenda↗

DOE OSTI2017

Applying Service-Oriented Architecture to Archiving Data in Control and Monitoring Systems

Current trends in the architecture of software systems focus our attention on building systems using a set of loosely coupled components, each providing a specific functionality known as service. It is not much different in control and monitoring systems, where a functionally distinct sub-system can be identified and independently designed, implemented, deployed and maintained. One functionality that renders itself perfectly to becoming a service is archiving the history of the system state. The design of such a service and our experience of using it are the topic of this article. The service is built with responsibility segregation in mind, therefore, it provides for reducing data processing on the data viewer side and separation of data access and modification operations. The service architecture and the details concerning its data store design are discussed. An implementation of a service client capable of archiving EPICS process variables (PV) and LabVIEW shared variables is presented. Data access tools, including a browser-based data viewer and a mobile viewer, are also presented.

Nogiec, J. M.↗

NASA NTRS1992

Plasma effects on the passive external thermal control coating of Space Station Freedom

The current baseline chromic acid anodized thermal control coating on 6061-T6 aluminum meteoroid debris (M/D) shields for SSF has been evaluated. The degradation of the solar absorptance, alpha, and the thermal emittance, epsilon, of chromic acid anodized aluminum due to dielectric breakdown in plasma was measured to predict the on-orbit lifetime of the SSF M/D shields. The lifetime of the thermal control coating was based on the surface temperatures achieved with degradation of the thermal control properties, alpha and epsilon. The temperatures of each M/D shield from first element launch (FEL) through FEL+15 years were analyzed. It is shown that the baseline thermal control coating cannot withstand the -140 V potential between the conductive structure of the SSF and the current plasma environment.

Carruth, Ralph, Jr.↗

NASA NTRS1985

Design considerations for application of laminar flow control systems to transport aircraft

The current status of the laminar-flow control LFC technology is summarized. Factors that have previously inhibited the application of LFC are first reviewed. Involved are the effects of atmospheric ice crystals, surface irregularities, acoustical environment, and off-design operating conditions. Aircraft design trends that are different from turbulent aircraft are discussed as are various design requirements unique to the LFC systems. Current design approaches for the principal LFC systems are reviewed. These include the system for protection of the leading-edge region from surface contamination and icing and the system for removal of a portion of the boundary-layer air. The latter includes consideration of both multiple spanwise suction slots and distributed perforations and required differences between the wing-box and leading-edge box regions.

Braslow, A. L.↗

DOE OSTI2019

Current Regulation in Contact Welding

Algorithms for current stabilization in the control of contact welding are considered. The proposed method for specifying and maintaining the welding current permits correction of the thyristor firing angle by means of an approximate formula taking account of the measured current-pulse parameters in phase regulation. The proposed method simplifies the equipment and increases the efficiency of regulation.

42 ENGINEERING↗

DOE OSTI2022

Benchmarking Real-Time Control Platforms Using a Matlab/Simulink Coder with Applications in the Control of DC/AC Switched Power Converters

In the control of DC/AC switched power converters (SPC), one of the most important aspects to be considered is the selection of the real-time control platform. The real-time control platform must be able to meet the high performance efficiency and regulation requirements of the DC/AC SPC, as these typically operate at switching frequencies in the order of kHz to MHz. For this reason, the hardware characteristics of the ADC and PWM, and the processing capacity of the real-time control platform are of vital importance when implementing advanced digital controllers that maintain voltage and current levels within regulatory standards. In this context, we aimed to perform a comparative study of the computation times of different real-time control platforms when implementing different control strategies for DC/AC switched power converters. We also analyzed the impact of the real-time control platforms on the THD of the voltages generated by the DC/AC switched power converters. With the help of this paper, researchers and developers will have criteria to select which real-time control platform to use in real-time control for DC/AC SPC applications.

42 ENGINEERING↗

NASA NTRS1996

A Hybrid Nonlinear Control Scheme for Active Magnetic Bearings

A nonlinear control scheme for active magnetic bearings is presented in this work. Magnet winding currents are chosen as control inputs for the electromechanical dynamics, which are linearized using feedback linearization. Then, the desired magnet currents are enforced by sliding mode control design of the electromagnetic dynamics. The overall control scheme is described by a multiple loop block diagram; the approach also falls in the class of nonlinear controls that are collectively known as the 'integrator backstepping' method. Control system hardware and new switching power electronics for implementing the controller are described. Various experiments and simulation results are presented to demonstrate the concepts' potentials.

Xia, F.↗

NASA NTRS1982

Thermal control for the 1990's

Current thermal distribution systems on large spacecraft, such as the Space Shuttle and Spacelab, use pumped fluid loops that circulate the coolant between a series of user stations and a single rejection point, involving complex plumbing and controls with a significant power penalty and limited reliability. In order to provide heat transport at near-isothermal conditions in future large spacecraft, two-phase flow systems will be implemented by taking advantage of the heat of vaporization and condensation of common working fluids at minimal expenditure of power and temperature variation. Such systems are considered for the cases of the thermal requirements of nearly 100 potential astrophysics and astronomy instruments. Data on temperature requirements, power dissipations, environmental fluxes, heat addition or rejection, and general description, are used to form conceptual designs for the thermal utility.

Ollendorf, S.↗

NASA NTRS1984

Recent developments in monolithic phase-locked semiconductor laser arrays

Coherent combination of the power of several semiconductor lasers fabricated on the same substrate has been the subject of an intense research effort in recent years, the main motivation being to obtain higher power levels than those available from a single laser in a stable radiation pattern. Best results reported so far include 2.6 Watts CW emitted power and less than 1 deg far-field angle (in the array plane) in arrays where all the lasers are electrically connected in parallel. A different type of coherent array, where each element has a separate contact, has been recently demonstrated. While requiring the more complex two-level metallization technology, applying a separate contact to each laser provides an additional degree of freedom in the design and the operation of monolithic arrays. The separate contacts can be employed to tailor the near-field and far-field distributions and to compensate for device-to-device nonuniformities. Furthermore, the control of the currents of the array elements allows the performance of a variety of other functions, such as beam scanning, spectral mode control, wavelength tuning and control of the mutual coherence between array elements.

Katz, J.↗

NASA NTRS1984

Recent developments in monolithic phase-locked semiconductor laser arrays

Coherent combination of the power of several semiconductor lasers fabricated on the same substrate has been the subject of an intense research effort in recent years, the main motivation being to obtain higher power levels than those available from a single laser in a stable radiation pattern. Best results reported so far include 2.6 watts CW emitted power and less than 1 deg far-field angle (in the array plane) in arrays where all the lasers are electrically connected in parallel. A different type of coherent array, where each element has a separate contact, has been recently demonstrated. While requiring the more complex two-level metallization technology, applying a separate contact to each laser provides an additional degree of freedom in the design and the operation of monolithic arrays. The separate contacts can be employed to tailor the near-field and far-field distributions and to compensate for device-to-device nonuniformities. Furthermore, the control of the currents of the array elements allows the performance of a variety of other functions, such as beam scanning, spectral mode control, wavelength tuning and control of the mutual coherence between array elements.

Katz, J.↗

NASA NTRS2017

Development of Trace Contaminant Control Prototypes for the Primary Life Support System (PLSS)

Results are presented on the development of Trace Contaminant Control (TCC) Prototypes for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). The current TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal, which is non-regenerable, and the carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. Data on sorption and desorption of ammonia and formaldehyde, which are major TCs of concern, as well as pressure-drop calculations were used to design and test 1/6-scale and full-scale trace contaminant control system (TCCS) prototypes. Carbon sorbents were fabricated in both the granular and foam-supported forms. Sorbent performance was tested for ammonia sorption and vacuum regeneration in 1/6-scale, and pressure-drop characteristics were measured at flow rates relevant to the PLSS application.

Wojtowicz, Marek↗

DOE OSTI2017

Development of a model based assessment process for qualification of embedded digital devices in NPP applications: research approach and current status - 263

The instrumentation and control (I and C) equipment used in currently operating U.S. nuclear power plants (NPPs) is primarily based on mature analog technologies that are progressing towards obsolescence. The continued reliance on this legacy analog technology, which is also being propagated into new NPP designs, imposes performance penalties and maintenance burdens in comparison with modern digital I and C instrumentation. In many instances, currently available I and C equipment contain embedded digital devices (EDDs) such as microprocessors and programmable logic devices. Experience in other industries, such as avionics, has shown that digital I and C equipment containing EDDs can provide significant benefits over analog-based equipment in terms of performance, reliability, and maintainability. In recent years, due to the high demand for digital technologies in the industrial I and C marketplace, it is becoming increasingly difficult for NPPs to acquire instrumentation that is not equipped with an EDD. However, the nuclear power industry has been slow to adopt digital technology, especially in safety-related systems, in large part as a result of regulatory concerns about common-cause failure (CCF) vulnerabilities of equipment with EDDs. Consequently, there is a clear need to develop cost effective qualification methods to contribute to the assessment of CCF vulnerability posed by EDDs in modern instrumentation that could be used in NPPs. This paper describes the research regarding qualification methods for equipment with EDDs that is sponsored by the Nuclear Energy Enabling Technologies (NEET) Advanced Sensors and Instrumentation (ASI) program of the U.S. Department of Energy (DOE). The purpose of the current research is to develop an effective approach employing science-based methods to resolve concerns about CCF vulnerability that serve to inhibit deployment of advanced instrumentation (e.g., sensors, actuators, microcontrollers) with EDDs in nuclear power applications. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

NASA NTRS2005

Unified Lunar Control Network 2005 and Topographic Model

There are currently two generally accepted lunar control networks. These are the Unified Lunar Control Network (ULCN) and the Clementine Lunar Control Network (CLCN), both derived by M. Davies and T. Colvin at RAND. We address here our efforts to merge and improve these networks into a new ULCN. The ULCN was described in the last major publication about a lunar control network. The statistics on this and the other networks discussed here. Images for this network are from the Apollo, Mariner 10, and Galileo missions, and Earth-based photographs. The importance of this network is that its accuracy is relatively well quantified and published information on the network is available. The CLCN includes measurements on 43,871 Clementine 750-nm images - the largest planetary control network ever computed. This purpose of this network was to determine the geometry for the Clementine Basemap Mosiac (CBM). The geometry of that mosaic was used to produce the Clementine UVVIS digital image model and the Near-Infrared Global Multispectral Map of the Moon from Clementine. Through the extensive use of these products, they and the underlying CLCN in effect define the generally accepted current coordinate system for reporting and describing the location of lunar coordinates. However, no publication describes the CLCN itself.

Archinal, B. A.↗