Showing papers on "TEC published in 1981"

Influence of solar sector boundaries on ionospheric variability

Abstract: A search for solar sector boundary related perturbations upon the ionospheric F region has been conducted by using a 3-year data base of ionospheric total electron content (TEC) observations from low to auroral latitudes. It has been found that as the earth passes from one sector to another, the daytime TEC from middle to high latitudes (L = 3-5) generally undergoes a change from relatively enhanced to relatively depleted TEC values. The opposite trend occurs at low latitudes (L = 2). The TEC variations are small in comparison with the overall F region variability and appear to be associated with the increased geomagnetic activity levels that occur when the earth enters into a new sector.

Storm Effects of Ionospheric Total Electron Content (TEC) at Low Latitudes

Abstract: The changes in the ionospheric Total Electron Content (TEC) obtained by the Faraday rotation method at a chain of low latitude stations all in India (longitude about 75E) are studied during a few selected geomagnetic storms mostly in winter of 1975-7b. For the location Octacamund very near the dip equator in India, TEC data were available by the Group delay method also, and these correlated very well with the TEC data obtained by the Faraday rotation method. Large changes of TEC, both positive and negative, were observed at all locations, but these did not bear any clear relationships either with the specific phases (Main Phase Onset, Recovery) or with the magnitude of the geomagnetic storms. Often, large changes were observed even before the Main Onset. The fountain effect, in which a strong equatorial electrojet is associated with a large noon-time bite-out in equatorial foF2 and a large equatorial anomaly (excess ionozation at the crests at about +30 dip angles) or, its reverse effect (a weak electrojet associated with a lack of foF2 bite-out and a decreased equatorial anomaly), were seen very clearly in some instances during or even before a geomagnetic storm. However, in many other cases, the fountain effect was largely distorted. It is surmised that apart from electric field effects, neutral winds not only of polar origin but probably of low latitude origin are creating large dynamic upheavals in the lowlatitude ionospheric regions, often in a random fashion, not only during geomagnetic storms but even before or long time after the storm onsets. If true, the origin of such winds needs investigation.

S/E/TEC - An Environment for the Production of Reliable Software

Abstract: S/E/TEC is a software engineering environment supporting the software producers' activities as well as management activities. The main components of S/E/TEC are the project model, the production techniques, the management techniques, the product patterns, the development standards, the project library and the terminal system PET/MAESTRO.

Thermionic Energy Conversion (TEC) topping thermoelectrics

Abstract: Performance expectations for thermionic and thermoelectric energy conversion systems are reviewed. It is noted that internal radiation effects diminish thermoelectric figures of merit significantly at 1000 K and substantially at 2000 K; the effective thermal conductivity contribution of intrathermoelectric radiative dissipation increases with the third power of temperature. It is argued that a consideration of thermoelectric power generation with high temperature heat sources should include utilization of thermionic energy conversion (TEC) topping thermoelectrics. However TEC alone or TEC topping more efficient conversion systems like steam or gas turbines, combined cycles, or Stirling engines would be more desirable generally.

Thermionic Energy Conversion and Metallic-Fluid Heat Pipes: High Power Densities from High-Temperature Material Interactions

Abstract: Thermionic energy conversion (TEC) and metallic-fluid heat pipes (MFHP) offer important and unique advantages in terrestrial and space energy processing. They are also well suited to serve together synergistically. TEC and MFHPS operate through working-fluid vaporization, condensation cycles that accept great thermal power densities at high temperatures. TEC and MFHPs have apparently simple, isolated performance mechanisms that are somewhat similar. And they also have obviously difficult, complected material problems that again are somewhat similar. Intensive investigation reveals that aspects of their operating cycles and material problems tend to merge: ''In short, high-temperature material effects determine the level and lifetime of ... performance.'' Simplified equations verify the preceding statement for TEC and MFHPs. Material properties and interactions exert primary influences on operational effectiveness. And thermophysicochemical stabilities dictate operating temperatures which regulate the thermoemissive currents of TEC and the vaporization flow rates of MFHPs. Major high-temperature material problems of TEC and MFHPs have been solved. These solutions lead to productive, cost-effective applications of current TEC and MFHPs — and point to significant improvements with anticipated technological gains.

Analysis of nuclear propagation effects utilizing wideband satellite data. Final report, 14 January 1980-30 January 1981

Abstract: Previous analyses of the Wideband Satellite data have emphasized the scale-size regime between 500 m and several tens of kilometers. In this report we describe the results of a detailed analysis of the auroral and equatorial total electron content (TEC) structure associated with the various scintillation phenomena. A nighttime equatorial anomaly was a prominent feature in the equatorial data, particularly as the solar cycle maximum approached. In the auroral data we found that an enhanced F region is the primary contributor to steep latitudinal TEC gradients. Because recent data have shown an abrupt steepening of the irregularity spectral density function near 500 m, a careful analysis of the mutual coherence function was performed to see if this feature could be detected in the Wideband scintillation data. The analysis did indeed reveal such a feature, which is evidently a permanent characteristic of the most severely disturbed equatorial irregularity continuum.

High power densities from high-temperature material interactions

Abstract: Thermionic energy conversion (TEC) and metallic-fluid heat pipes (MFHPs), offering unique advantages in terrestrial and space energy processing by virtue of operating on working-fluid vaporization/condensation cycles that accept great thermal power densities at high temperatures, share complex materials problems. Simplified equations are presented that verify and solve such problems, suggesting the possibility of cost-effective applications in the near term for TEC and MFHP devices. Among the problems discussed are: the limitation of alkali-metal corrosion, protection against hot external gases, external and internal vaporization, interfacial reactions and diffusion, expansion coefficient matching, and creep deformation.

Analysis of Nuclear Propagation Effects Utilizing Wideband Satellite Data.

Abstract: : Previous analyses of the Wideband Satellite data have emphasized the scale-size regime between 500 m and several tens of kilometers. In this report we describe the results of a detailed analysis of the auroral and equatorial total electron content (TEC) structure associated with the various scintillation phenomena. A nighttime equatorial anomaly was a priminent feature in the equatorial data, particularly as the solar cycle maximum approached. In the auroral data we found that an enhanced F region is the primary contributor to steep latitudinal TEC gradients. Because recent data have shown an abrupt steepening of the irregularity spectral density function near 500 m, a careful analysis of the mutual coherence function was performed to see if this feature could be detected in the Wideband scintillation data. The analysis did indeed reveal such a feature, which is evidently a permanent characteristic of the most severely disturbed equatorial irregularity continuum. (Author)