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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Design Methods, Tools, and Data for Ceramic Solar Receivers

This report presents the development of tools and methods for evaluating the reliability and performance of ceramic materials in high temperature solar receivers. As Concentrating Solar Power (CSP) technologies aim for higher operating temperatures to enhance efficiency and meet industrial process heat requirements, current high temperature metallic materials face challenges in maintaining structural integrity. This report explores advanced ceramics as a promising alternative, given their superior high temperature strength and lower thermal expansion, compared to metals. To address the need for effective ceramic receiver design tools, this report integrates statistical failure models of ceramics into the existing srlife tool: an open-source software package designed to estimate the life of high temperature CSP components. These failure models account for the inherent variability and flaw distribution in ceramics, as well as the impact of subcritical crack growth under high temperature cyclic loads. The report also presents experimental data collected for a commercially available ceramic material, SiC, and details the process of estimating reliability model parameters from these data. A comparative design analysis is then performed between ceramic (SiC) and metallic (current nickel-based superalloys A740H and A282) receiver. This comparison demonstrates that SiC receivers can achieve service life exceeding 30 years under high incident heat flux conditions, compared to just a few years for metallic receivers.

14 SOLAR ENERGY↗
NASA NTRS1972

Optimization in the design of a 12 gigahertz low cost ground receiving system for broadcast satellites. Volume 1: System design, performance, and cost analysis

The technical and economical feasibility of using the 12 GHz band for broadcasting from satellites were examined. Among the assigned frequency bands for broadcast satellites, the 12 GHz band system offers the most channels. It also has the least interference on and from the terrestrial communication links. The system design and analysis are carried out on the basis of a decision analysis model. Technical difficulties in achieving low-cost 12 GHz ground receivers are solved by making use of a die cast aluminum packaging, a hybrid integrated circuit mixer, a cavity stabilized Gunn oscillator and other state-of-the-art microwave technologies for the receiver front-end. A working model was designed and tested, which used frequency modulation. A final design for the 2.6 GHz system ground receiver is also presented. The cost of the ground-terminal was analyzed and minimized for a given figure-of-merit (a ratio of receiving antenna gain to receiver system noise temperature). The results were used to analyze the performance and cost of the whole satellite system.

Ohkubo, K.↗
NASA NTRS1972

OMEGA timing receiver, design and system test

The design of a two frequency OMEGA Timing Receiver is discussed. The receiver tracks the arrival time of the signals by precise phase matching at the receiving antenna. Provision is made for inserting a propagation delay correction for each signal path. Time is measured as the difference between the zero crossing coincidence of the corrected signals and the local time. This number is displayed on the front panel in microseconds. The receiver can also function as a precise phase tracking receiver for collection of propagation data essential to augmenting the propagation corrections. All phase and time information is made available in a BCD format for flexibility in interfacing with other equipment. Results of preliminary tests using experimental transmissions are given. Preliminary results indicate time may be transferred by this technique to an accuracy of a few microseconds.

Wilson, J. J.↗
NASA NTRS1976

Flight test of 4-Hz and 30-Hz Omega receiver front-end

In-flight information was gathered on two Omega receiver analog modules, one having a 4-Hz bandwidth and the other a 30-Hz bandwidth. The Mini-O receiver was also monitored. An improved signal-to-noise characteristic of the narrower bandwidth front-end with negligible loss in dynamic range indicates that the 4-Hz front-end is the more desirable for the prototype Omega receivers. The Mini-O receiver was found to function quite satisfactorily on its second test flight, and has a very real potential for a low-cost, low-power, compact and light-weight Omega receiver.

Wright, L.↗
NASA NTRS1976

Possible methods for USSR-VLF navigation receivers

The U.S.S.R. has a VLF navigation system similar to OMEGA. Beukers has reported some information on the signal format, frequencies used, and the probable radiated power levels. From this data it appears possible to derive receiver operation modes and some implied reasons for the unique choice of the time-multiplexed frequency time base used. Of interest are receiver methods requiring processor gate complexity similar to a digital wristwatch including the use of mass-produced low frequency quartz crystal reference oscillators. The stability required of the local reference oscillator is probably much less critical than for other VLF receivers because of the signal format. One conclusion is that U.S.S.R.-VLF receivers might be fabricated at quite low cost making it possible for all persons in remote areas each to have his own private positioning aid. Further study of the actual transmitted signal format is warranted. While the nature of this memorandum is speculative because of the lack of confirming data, the receiver method proposed has evolved from related principles which have been applied to the operating OMEGA-VLF navigation system.

Burhans, R. W.↗
NASA NTRS1978

Optimization of MLS receivers for multipath environments

Reduced order receiver (suboptimal receiver) analysis in multipath environments is presented. The origin and objective of MLS is described briefly. Signal modeling in MLS the optimum receiver is also included and a description of a computer oriented technique which was used in the simulation study of the suboptimal receiver is provided. Results and conclusion obtained from the research for the suboptimal receiver are reported.

Mcalpine, G. A.↗
NASA NTRS1979

Optimization of MLS receivers for multipath environments

The angle tracking problems in microwave landing system receivers along with a receiver design capable of optimal performance in the multipath environments found in air terminal areas were studied. Included were various theoretical and evaluative studies like: (1) signal model development; (2) derivation of optimal receiver structures; and (3) development and use of computer simulations for receiver algorithm evaluation. The development of an experimental receiver for flight testing is presented. An overview of the work and summary of principal results and conclusions are reported.

Mcalpine, G. A.↗
NASA NTRS1978

A versatile microprocessor-controlled hybrid receiver

A hybrid receiver has been designed for the Galileo Project. The receiver, located on the Galileo Orbiter, will autonomously acquire and track signals from the first atmospheric probe of Jupiter as well as demodulate, bit-synchronize, and buffer the telemetry data. The receiver has a conventional RF and LF front end but performs multiple functions digitally under firmware control. It will be a self-acquiring receiver that operates under a large frequency uncertainty; it can accommodate different modulation types, bit rates, and other parameter changes via reprogramming. A breadboard receiver and test set demonstrate a preliminary version of the sequential detection process and verify the hypothesis that a fading channel does not reduce the probability of detection.

Grant, T. L.↗
NASA NTRS1980

Advanced solar thermal receiver technology

Development of advanced receiver technology for solar thermal receivers designed for electric power generation or for industrial applications, such as fuels and chemical production or industrial process heat, is described. The development of this technology is focused on receivers that operate from 1000 F to 3000 F and above. Development strategy is mapped in terms of application requirements, and the related system and technical requirements. Receiver performance requirements and current development efforts are covered for five classes of receiver applications: high temperature, advanced Brayton, Stirling, and Rankine cycle engines, and fuels and chemicals.

Kudirka, A. A.↗
NASA NTRS1983

Radiation energy receiver for laser and solar propulsion systems

The concept of remotely heating a rocket propellant with a high intensity radiant energy flux is especially attractive due to its high specific impulse and large payload mass capabilities. In this paper, a radiation receiver-thruster which is especially suited to the particular thermodynamic and spectral characteristics of highly concentrated solar energy is proposed. In this receiver, radiant energy is volumetrically absorbed within a hydrogen gas seeded with alkali metal vapors. The alkali atoms and molecules absorb the radiant flux and, subsequently, transfer their internal excitation to hydrogen molecules through collisional quenching. It is shown that such a radiation receiver would outperform a blackbody cavity type receiver in both efficiency and maximum operating temperatures. A solar rocket equipped with such a receiver-thruster would deliver thrusts of several hundred newtons at a specific impulse of 1000 seconds.

Rault, D. F. G.↗
NASA NTRS1983

EHF low-noise FET receiver

Extremely high frequency (EHF) receivers for military and NASA programs must be small, lightweight, and highly reliable. In connection with recent advances in the development of mm-wave FET devices and circuits, a basis has been obtained for the eventual replacement of diode mixer front-ends by FET preamplifiers in receivers up to 94 GHz. By placing a low noise amplifier in front of the mixer it is possible to achieve a lower system noise figure than that found in conventional mm-wave receivers. A broader bandwidth can also be provided. Attention is given to the receiver configuration, a low noise FET amplifier, an image rejection filter, a dual-gate FET mixer, a FET local oscillator, and a FET receiver.

Schellenberg, J. M.↗
NASA NTRS1983

High dynamic, low volume GPS receiver

A new GPS receiver concept and design are presented to meet the high dynamic and low volume requirements for range applications in missiles and drones. The receiver has the potential to satisfy all range requirements with one basic receiver, which has significant potential economic benefit over the alternate approach of using a family of receivers, each tailored for specific applications. The main new concept is to use approximate maximum likelihood estimates of pseudo range and range-rate, rather than tracking with carrier phase locked loops and code delay locked loops. Preliminary analysis indicates that receivers accelerating at 50 g or more can track with position errors due to acceleration of approximately 0.2 m/g, or 10 m at 50 g. Implementation is almost entirely digital to meet the low volume requirements.

Hurd, W. J.↗
NASA NTRS1985

GPS high dynamic receiver tracking demonstration results

Demonstration results are presented for a high dynamic GPS receiver. The receiver tested is a breadboard unit capable of tracking one simulated satellite signal in pseudorange and range rate. The receiver makes approximate maximum likelihood estimates of pseudorange and range rate each 20 ms, and tracks these observables using a third order filter with a time constant of 0.14 s. Carrier phase is not tracked, which eliminates the typical failure mode of loss of carrier lock associated with PLLs at high dynamics. The receiver tracks with pseudorange lag errors of under 0.06 m when subjected to simulated 50 g turns with 40 g/s peak jerk. Pseudorange errors due to receiver noise alone are approximately 0.6 m rms at a carrier power to noise spectral density ratio of 34 dB-Hz. The tracking threshold SNR is approximately 28 dB-Hz, which provides 12 dB margin relative to the 40 dB-Hz that occurs with minimum specified satellite signal strength, 3.5 dB system noise figure, and 0 dBi antenna gain.

Hurd, W. J.↗
NASA NTRS1987

More Efficient Solar Thermal-Energy Receiver

Thermal stresses and reradiation reduced. Improved design for solar thermal-energy receiver overcomes three major deficiencies of solar dynamic receivers described in literature. Concentrator and receiver part of solar-thermal-energy system. Receiver divided into radiation section and storage section. Concentrated solar radiation falls on boiling ends of heat pipes, which transmit heat to thermal-energy-storage medium. Receiver used in number of applications to produce thermal energy directly for use or to store thermal energy for subsequent use in heat engine.

Dustin, M. O.↗
NASA NTRS1987

Development of an integrated heat pipe-thermal storage system for a solar receiver

The Organic Rankine Cycle (ORC) Solar Dynamic Power System (SDPS) is one of the candidates for Space Station prime power application. In the low Earth orbit of the Space Station approximately 34 minutes of the 94-minute orbital period is spent in eclipse with no solar energy input to the power system. For this period the SDPS will use thermal energy storage (TES) material to provide a constant power output. An integrated heat-pipe thermal storage receiver system is being developed as part of the ORC-SDPS solar receiver. This system incorporates potassium heat pipe elements to absorb and transfer the solar energy within the receiver cavity. The heat pipes contain the TES canisters within the potassium vapor space with the toluene heater tube used as the condenser region of the heat pipe. During the insolation period of the Earth orbit, solar energy is delivered to the heat pipe in the ORC-SDPS receiver cavity. The heat pipe transforms the non-uniform solar flux incident in the heat pipe surface within the receiver cavity to an essentially uniform flux at the potassium vapor condensation interface in the heat pipe. During solar insolation, part of the thermal energy is delivered to the heater tube and the balance is stored in the TES units. During the eclipse period of the orbit, the balance stored in the TES units is transferred by the potassium vapor to the toluene heater tube.

Keddy, E. S.↗
NASA NTRS1987

Advanced solar receiver conceptual design study

High temperature solar dynamic Brayton and Stirling receivers are investigated as candidate electrical power generating systems for future LEO missions. These receivers are smaller and more efficient than conventional receivers, and they offer less structural complexity and fewer thermal stress problems. Use of the advanced Direct Absorption Storage Receiver allows many of the problems associated with working with high-volumetric-change phase-change materials to be avoided. A specific mass reduction of about 1/3 with respect to the baseline receiver has been realized.

Kesseli, J. B.↗
NASA NTRS1988

Efficient detection and signal parameter estimation with applications to high dynamic GPS receivers

A novel technique for simultaneously detecting data and estimating the parameters of a received carrier signal phase modulated by unknown data and experiencing very high Doppler, Doppler rate, etc. is discussed. Such a situation arises, for example, in the case of Global Positioning Systems (DPS) where the signal parameters are directly related to the position, velocity and acceleration of the GPS receiver. The proposed scheme is based upon first estimating the received signal local (data dependent) parameters over two consecutive bit periods, followed by the detection of a possible jump in these parameters. The presence of a detected jump signifies a data transition which is then removed from the received signal. This effectively demodulated signal is then processed to provide the estimates of global (data independent) parameters of the signal related to the position, velocity, etc. of the receiver. One of the key features of the proposed algorithm is the introduction of two different schemes which can provide an improvement of up to 3 dB over the conventional implementation of Kalman filter as applied to phase and frequency estimation, under low to medium signal-to-noise ratio conditions.

Kumar, R.↗
NASA NTRS1988

The development of an advanced generic solar dynamic heat receiver thermal model

An advanced generic solar dynamic heat receiver thermal model under development which can analyze both orbital transient and orbital average conditions is discussed. This model can be used to study advanced receiver concepts, evaluate receiver concepts under development, analyze receiver thermal characteristics under various operational conditions, and evaluate solar dynamic system thermal performances in various orbit conditions. The model and the basic considerations that led to its creation are described, and results based on a set of baseline orbit, configuration, and operational conditions are presented to demonstrate the working of the receiver model.

Wu, Y. C.↗