Microwave Power Transmission System Studies. Volume 1: Executive Summary

A study of microwave power generation, transmission, reception and control was conducted as a part of a program to demonstrate the feasibility of power transmission from geosynchronous orbit. A summary is presented of results concerning design approaches, estimated costs (ROM), critical technology, associated ground and orbital test programs with emphasis on dc to rf conversion, transmitting antenna, phase control, mechanical systems, flight operations, ground power receiving-rectifying antenna with systems analysis, and evaluation. Recommendations for early further in-depth studies complementing the technology program are included

Microwave power transmission system studies. Volume 2: Introduction, organization, environmental and spaceborne systems analyses

Introduction, organization, analyses, conclusions, and recommendations for each of the spaceborne subsystems are presented. Environmental effects - propagation analyses are presented with appendices covering radio wave diffraction by random ionospheric irregularities, self-focusing plasma instabilities and ohmic heating of the D-region. Analyses of dc to rf conversion subsystems and system considerations for both the amplitron and the klystron are included with appendices for the klystron covering cavity circuit calculations, output power of the solenoid-focused klystron, thermal control system, and confined flow focusing of a relativistic beam. The photovoltaic power source characteristics are discussed as they apply to interfacing with the power distribution flow paths, magnetic field interaction, dc to rf converter protection, power distribution including estimates for the power budget, weights, and costs. Analyses for the transmitting antenna consider the aperture illumination and size, with associated efficiencies and ground power distributions. Analyses of subarray types and dimensions, attitude error, flatness, phase error, subarray layout, frequency tolerance, attenuation, waveguide dimensional tolerances, mechanical including thermal considerations are included. Implications associated with transportation, assembly and packaging, attitude control and alignment are discussed. The phase front control subsystem, including both ground based pilot signal driven adaptive and ground command approaches with their associated phase errors, are analyzed

Farming today for young men and women

It would be impossible to list here all the advantages of farming. There are many. It is a life in the open, with a high degree of personal independence. There is opportunity to work closely as a family group. But if you’ve decided to farm because you’ve heard it’s an “ easy racket,” perhaps you’d better do some more thinking. Farming isn’t easy. Some years it’s tough. It’s a mistake to be misled by the war and immediate postwar picture. Conditions aren’t likely to stay this bright. We’re already hearing notes of warning about the price recessions— and even of depression. Prices undoubtedly will work downward after the present food emergency eases. Those of you who were raised on the farm know about the hard work. Those of you who weren’t should be aware of it. And you should know that the weather plays a mighty important part in your lives. Income is seasonal. Most farm homes are not as modern or as convenient as those in the city. Gay entertainment is not quite as close. If you are married, your wife, too, should be acquainted with the differences between farm and city living, because farming is a family affair

Molecular evidence for gender differences in the migratory behaviour of a small seabird

Molecular sexing revealed an unexpectedly strong female bias in the sex ratio of pre-breeding European Storm Petrels (Hydrobates pelagicus), attracted to playback of conspecific calls during their northwards migration past SW Europe. This bias was consistent across seven years, ranging from 80.8% to 89.7% female (mean annual sex ratio ± SD = 85.5% female ±4.1%). The sex ratio did not differ significantly from unity (i.e., 50% female) among (i) Storm Petrel chicks at a breeding colony in NW France, (ii) adults found dead on beaches in Southern Portugal, (iii) breeding birds attending nest burrows in the UK, captured by hand, and (iv) adults captured near a breeding colony in the UK using copies of the same sound recordings as used in Southern Europe, indicating that females are not inherently more strongly attracted to playback calls than males. A morphological discriminant function analysis failed to provide a good separation of the sexes, showing the importance of molecular sexing for this species. We found no sex difference in the seasonal or nocturnal timing of migration past Southern Europe, but there was a significant tendency for birds to be caught in sex-specific aggregations. The preponderance of females captured in Southern Europe suggests that the sexes may differ in migration route or in their colony-prospecting behaviour during migration, at sites far away from their natal colonies. Such differences in migration behaviour between males and females are poorly understood but have implications for the vulnerability of seabirds to pollution and environmental change at sea during the non-breeding season

Standardized ASCE Penman-Monteith: Impact of sum-of-hourly vs. 24-hour timestep computations at reference weather station sites

ABSTRACT. The standardized ASCE Penman-Monteith (ASCE-PM) model was used to estimate grass-reference evapotran-spiration (ETo) over a range of climates at seven locations based on hourly and 24 h weather data. Hourly ETo computations were summed over 24 h periods and reported as sum-of-hourly (SOH). The SOH ASCE-PM ETo values (ETo,h,ASCE) were compared with the 24 h timestep ASCE-PM ETo values (ETo,d) and SOH ETo values using the FAO Paper 56 Penman-Monteith (FAO56-PM) method (ETo,h,FAO). The ETo,h,ASCE values were used as the basis for comparison. The ETo,d estimated higher than ETo,h,ASCE at all locations except one, and agreement between the computational timesteps was best in humid regions. The greatest differences between ETo,d and ETo,h,ASCE were in locations where strong, dry, hot winds cause advective increases in ETo. Three locations showed considerable signs of advection. Some of the differences between the timesteps was attributed to uncertainties in predicting soil heat flux and to the difficulty of ETo,d to effectively account for abrupt diurnal changes in wind speed, air temperature, and vapor pressure deficit. The ETo,h,FAO values correlated well with ETo,h,ASCE values (r2> 0.997), but estimated lower than ETo,h,ASCE at all locations by 5 % to 8%. This was due to the impact of higher surface resistance during daytime periods. Summing the ETo values over a weekly, monthly, or annual basis generally reduced the differences between ETo,d and ETo,h,ASCE. Summing the ETo,d values over multiple days and longer periods for peak ETo months resulted in inconsistent differences between the two timesteps. The results suggest a potential improvement in accuracy when using the standardized ASCE-PM procedure applied hourly rather than daily. The hourly application helps to account for abrupt changes in atmospheric conditions on ETo estimation in advective and other environments when hourly climate data are available

An outburst from a massive star 40 days before a supernova explosion

Various lines of evidence suggest that very massive stars experience extreme mass-loss episodes shortly before they explode as a supernova. Interestingly, several models predict such pre-explosion outbursts. Establishing a causal connection between these mass-loss episodes and the final supernova explosion will provide a novel way to study pre-supernova massive-star evolution. Here we report on observations of a remarkable mass-loss event detected 40 days prior to the explosion of the Type IIn supernova SN 2010mc (PTF 10tel). Our photometric and spectroscopic data suggest that this event is a result of an energetic outburst, radiating at least 6x10^47 erg of energy, and releasing about 0.01 Solar mass at typical velocities of 2000 km/s. We show that the temporal proximity of the mass-loss outburst and the supernova explosion implies a causal connection between them. Moreover, we find that the outburst luminosity and velocity are consistent with the predictions of the wave-driven pulsation model and disfavor alternative suggestions.Comment: Nature 494, 65, including supplementary informatio

Measurement of the half-life of the T=12\frac{1}{2} mirror decay of 19^{19}Ne and its implication on physics beyond the standard model

The $\frac{1}{2}^+ \rightarrow \frac{1}{2}^+$ superallowed mixed mirror decay of $^{19}$Ne to $^{19}$F is excellently suited for high precision studies of the weak interaction. However, there is some disagreement on the value of the half-life. In a new measurement we have determined this quantity to be $T_{1/2}$ = $17.2832 \pm 0.0051_{(stat)}$ $\pm 0.0066_{(sys)}$ s, which differs from the previous world average by 3 standard deviations. The impact of this measurement on limits for physics beyond the standard model such as the presence of tensor currents is discussed.Comment: 5 pages, 3 figures, 1 tabl

Variability Analyses of Alfalfa-Reference to Grass-Reference Evapotranspiration Ratios in Growing and Dormant Seasons

Alfalfa-reference evapotranspiration (ETr) values sometimes need to be converted to grass-reference ET (ETo), or vice versa, to enable crop coefficients developed for one reference surface to be used with the other. However, guidelines to make these conversions are lacking. The objectives of this study were to: (1) develop ETr to ETo ratios (Kr values) for different climatic regions for the growing season and nongrowing (dormant) seasons; and (2) determine the seasonal behavior of Kr values between the locations and in the same location for different seasons. Monthly average Kr values from daily values were developed for Bushland, (Tex.), Clay Center, (Neb.), Davis, (Calif.), Gainesville, (Fla.), Phoenix (Ariz.), and Rockport, (Mo.) for the calendar year and for the growing season (May– September). ETr and ETo values that were used to determine Kr values were calculated by several methods. Methods included the standardized American Society of Civil Engineers Penman–Monteith (ASCE-PM), Food and Agriculture Organization Paper 56 (FAO56) equation (68), 1972 and 1982 Kimberly-Penman, 1963 Jensen-Haise, and the High Plains Regional Climate Center (HPRCC) Penman. The Kr values determined by the same and different methods exhibited substantial variations among locations. For example, the Kr values developed with the ASCE-PM method in July were 1.38, 1.27, 1.32, 1.11, 1.28, and 1.19, for Bushland, Clay Center, Davis, Gainesville, Phoenix, and Rockport, respectively. The variability in the Kr values among locations justifies the need for developing local Kr values because the values did not appear to be transferable among locations. In general, variations in Kr values were less for the growing season than for the calendar year. Average standard deviation between years was maximum 0.13 for the calendar year and maximum 0.10 for the growing season. The ASCE-PM Kr values had less variability among locations than those obtained with other methods. The FAO56 procedure Kr values had higher variability among locations, especially for areas with low relative humidity and high wind speed. The 1972 Kim-Pen method resulted in the closest Kr values compared with the ASCE-PM method at all locations. Some of the methods, including the ASCE-PM, produced potentially unrealistically high Kr values (e.g., 1.78, 1.80) during the nongrowing season, which could be due to instabilities and uncertainties that exist when estimating ETr and ETo in dormant season since the hypothetical reference conditions are usually not met during this period in most locations. Because simultaneous and direct measurements of the ETr and ETo values rarely exist, it appears that the approach of ETr to ETo ratios calculated with the ASCE-PM method is currently the best approach available to derive Kr values for locations where these measurements are not available. The Kr values developed in this study can be useful for making conversions from ETr to ETo, or vice versa, to enable using crop coefficients developed for one reference surface with the other to determine actual crop water use for locations, with similar climatic characteristics of this study, when locally measured Kr values are not available

The Subluminous and Peculiar Type Ia Supernova PTF09dav

PTF09dav is a peculiar subluminous type Ia supernova (SN) discovered by the Palomar Transient Factory (PTF). Spectroscopically, it appears superficially similar to the class of subluminous SN1991bg-like SNe, but it has several unusual features which make it stand out from this population. Its peak luminosity is fainter than any previously discovered SN1991bg-like SN Ia (M_B -15.5), but without the unusually red optical colors expected if the faint luminosity were due to extinction. The photospheric optical spectra have very unusual strong lines of Sc II and Mg I, with possible Sr II, together with stronger than average Ti II and low velocities of ~6000 km/s. The host galaxy of PTF09dav is ambiguous. The SN lies either on the extreme outskirts (~41kpc) of a spiral galaxy, or in an very faint (M_R>-12.8) dwarf galaxy, unlike other 1991bg-like SNe which are invariably associated with massive, old stellar populations. PTF09dav is also an outlier on the light-curve-width--luminosity and color--luminosity relations derived for other sub-luminous SNe Ia. The inferred 56Ni mass is small (0.019+/-0.003Msun), as is the estimated ejecta mass of 0.36Msun. Taken together, these properties make PTF09dav a remarkable event. We discuss various physical models that could explain PTF09dav. Helium shell detonation or deflagration on the surface of a CO white-dwarf can explain some of the features of PTF09dav, including the presence of Sc and the low photospheric velocities, but the observed Si and Mg are not predicted to be very abundant in these models. We conclude that no single model is currently capable of explaining all of the observed signatures of PTF09dav.Comment: Accepted for publication in Ap