Atlas of electron content values observed at Urbana, Illinois, 1 December 1967 - 30 December 1970

Ionospheric electron content versus local time data deduced from Faraday rotation observations of ATS-III geostationary satellite signals at Urbana, Illinois are reported. The data are presented in two forms. Values of subionospheric latitude (SILAT) and subionospheric longitude (SILON) are in degrees north and degrees west, respectively. These are computed on the basis of 350 km for the mean ionospheric height, which value is also used for the calculation of the geometric-magnetic factor, required for the conversion of the measured Faraday rotation angle to electron content. Entries of zero for the electron content in the tables represent no data for those times

Ionospheric electron content at temperate latitudes during the declining phase of the sunspot cycle

Ionospheric electron density during declining phase of sunspot cycle by Faraday effect observation

Alien Registration- Flaherty, John B. (Portland, Cumberland County)

https://digitalmaine.com/alien_docs/23707/thumbnail.jp

A very high frequency radio interferometer for investigating ionospheric disturbances using geostationary satellites. Determination of changes in exospheric electron content by a comparison of group delay and Faraday rotation

The theory and development of a VHF correlation radio interferometer for investigating ionospheric disturbances are discussed. The system was developed to receive signals from the geostationary Applications Technology Satellites. Amplitude and phase variations of the signal passing through the ionosphere can be detected by this instrument. The system consists of two superheterodyne receivers separated by a distance known as the baseline of the system. Since the system is a phase sensitive instrument, the local oscillators of the two receivers must be phase coherent. This is accomplished by using phase-locked loops for generating the local oscillators. The two signals from the separate receivers are cross-correlated by multiplying the two signals together and then time averaging the result. The sensitivity of the instrument is increased by off-setting one of the local oscillators by a small amount

Wave propagation and earth satellite radio emission studies

Radio propagation studies of the ionosphere using satellite radio beacons are described. The ionosphere is known as a dispersive, inhomogeneous, irregular and sometimes even nonlinear medium. After traversing through the ionosphere the radio signal bears signatures of these characteristics. A study of these signatures will be helpful in two areas: (1) It will assist in learning the behavior of the medium, in this case the ionosphere. (2) It will provide information of the kind of signal characteristics and statistics to be expected for communication and navigational satellite systems that use the similar geometry

High power operation of an X-band gyrotwistron

We report the first experimental verification of a gyrotwistron amplifier. The device utilized a single 9.858 GHz, TE011 cavity, a heavily attenuated drift tube, and a long tapered output waveguide section. With a 440 kV, 200-245 A, 1 μs electron beam and a sharply tapered axial magnetic field, peak powers above 21 MW were achieved with a gain near 24 dB. Performance was limited by competition from a fundamental TE11 mode. A multimode code was developed to analyze this system, and simulations were in good agreement with the experiment

Considerations for a design and operations knowledge support system for Space Station Freedom

Engineering and operations of modern engineered systems depend critically upon detailed design and operations knowledge that is accurate and authoritative. A design and operations knowledge support system (DOKSS) is a modern computer-based information system providing knowledge about the creation, evolution, and growth of an engineered system. The purpose of a DOKSS is to provide convenient and effective access to this multifaceted information. The complexity of Space Station Freedom's (SSF's) systems, elements, interfaces, and organizations makes convenient access to design knowledge especially important, when compared to simpler systems. The life cycle length, being 30 or more years, adds a new dimension to space operations, maintenance, and evolution. Provided here is a review and discussion of design knowledge support systems to be delivered and operated as a critical part of the engineered system. A concept of a DOKSS for Space Station Freedom (SSF) is presented. This is followed by a detailed discussion of a DOKSS for the Lyndon B. Johnson Space Center and Work Package-2 portions of SSF

Seasonal Distribution and Abundance of Blue Crabs (Callinectes sapidus) in the Tampa Bay Estuary

Blue crabs (Callinectes sapidus (Rathbun)) are commercially important and are an integral part of the estuarine ecosystem as both predators and prey. Although adult blue crabs have been the focus of many studies, there is little published information on immature blue crab abundances, especially on the west Florida coast. The objectives of this study were to analyze the distributions and abundances of immature and adult blue crabs in the Tampa Bay estuary, specifically as they relate to 1) monthly and yearly trends in abundance and size, 2) timing of recruitment to the estuary, 3) sex- and size-determined distribution patterns, and 4) the influence of environmental factors, such as freshwater input. Catch rates, length frequencies, and indices of abundance were calculated for recruiting [≤20-mm carapace widths (CW)], juvenile (21–80-mm CW), and adult (\u3e80-mm CW) blue crabs caught during 1996 and 1997. Abundances of all size classes of blue crabs differed by region and month; juvenile and adult abundances were also significantly related to salinity. Immature crabs were collected in all months, confirming an extended spawning season, but there were elevated catches of recruiting blue crabs in February and September. Adults were caught year-round, with males generally being more abundant than females. Geographical regions close to the mouth of the bay had the highest densities of recruits, perhaps because of the supply of larvae being delivered to that area from offshore. With the use of monthly seine and river trawl data from an extended time period (1996–2004), annual variations in the abundance of immature and adult blue crabs were examined. A decline in the abundance of immature crabs collected in 21.3-m seines began after 1998, with a significant low occurring in 2002. A similar pattern was observed for adults collected in river trawls and by commercial fisheries. Unfavorable salinity regimes during this time period may have contributed to these abundance trends