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911.
L A Somova N S Pechurkin V I Polonsky T I Pisman A B Sarangova M Andre G M Sadovskaya 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,20(10):1939-1943
The effect has been studied of inoculation of seeds of wheat with two species of rhizospheric microorganisms--Pseudomonas fluorescens and Pseudomonas putida--on young plant growth with complete and with nitrogen deficit mineral nutrition. With complete mineral medium, plants grown from seeds inoculated with bacteria of Pseudomonas genus (experiment plants) have been found to have better growth over plants not inoculated with these bacteria (control plants). The experiment plants had increased transpiration and their biomass had higher organic nitrogen content. With nitrogen deficit medium, the plants inoculated with bacteria and those without them, have not revealed changes in growth. Neither case demonstrated competition of microorganisms with plants for nitrogen sources. 相似文献
912.
913.
D. Hovestadt G. Gloeckler H. H?fner B. Klecker C.Y. Fan L.A. Fisk F.M. Ipavich J.J. OGallagher M. Scholar 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(3):61-64
The ionic charge states of helium, carbon, oxygen, and iron have been determined for three solar particle enhancements by an electrostatic deflection analyzer, which is combined with a thin window proportional counter dE/dX vs. E system. The observations are obtained during the periods September 23 to 29, 1978, June 6 to 8, 1979, and September 15 to 26, 1979, with an instrument onboard the ISEE-3 spacecraft. The mean ionic charge states for He, C, and oxygen exhibit a high degree of ionization with values of Q = 2, 6, and 7.2, respectively. The charge state of iron is near 13 charge units. Variations from flare to flare and within the September 23, 1978 flare are small. The most surprising feature of the charge state measurement is the observation of a small (~10%) but finite contribution of singly ionized helium. 相似文献
914.
In a phased array antenna, the phase shifters (or T/R modules in an active aperture phased array) with their beam-steering control circuitry along with the feed network account for the major hardware cost. This paper presents two antenna array configurations that use simpler feed, simpler phase-shifting and simpler beam-steering control circuitry for realizing low-cost phased arrays. Both are lens configurations. The first one uses a Radant lens, which provides a medium that is loaded with diodes and provides the needed phase shift by switching the diodes on and off. The other configuration employs a ferroelectric dielectric material whose dielectric constant can be varied with an applied DC bias voltage. It is shown that the ferroelectric lens may have further advantages of smaller thickness, simpler beam-steering controls and lower cost 相似文献
915.
The first 8.5m infrared heterodyne spectrometer has been constructed using tuneable semiconductor (PbSe) diode lasers and was used to measure absorption line profiles of N2O in the laboratory and black body emission from the Moon and from Mars. Spectral information was recorded over a 200 MHz bandwidth using an 8-channel filter bank. The resolution was 25 MHz (6 × 10–6
m) and the minimum detectable (black-body) power was 1 × 10–16 W for 8 min of integration. The results demonstrate the usefulness of heterodyne spectroscopy for the study of remote and local sources in the infrared.We wish to thank Dr Jack Butler and Craig Simpson (Arthur D. Little, Inc.) for their continuing (and successful) efforts to grow better diode lasers during the course of this experiment. We thank the National Radio Astronomy Observatory for the loan of a 40-channel filter bank and associated mini-computer.We thank en masse the dozens of people who loaned equipment to us for the duration of this experiment, and the commercial firms (especially Harshaw, Inc.) which expedited orders for crucial equipment. We thank Dr Bertram Donn, Dr Norman Ness, and Dr George Pieper for administrative, scientific, and financial support; and we thank Mr James Faris for technical assistance and Dr Sol Glicker for preparation of sample gas cells. We thank Dr Thomas Clark for providing the Kohoutek ephemeris, sighting printout, and predicted molecular line positions and for advice and the loan of some equipment. Finally, we wish to acknowledge the strong support accorded us by our wives and families who scarcely saw us during this period. 相似文献
916.
P.B. Russell M.P. McCormick T.J. Swissler 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(5):123-126
The satellite sensors SAM II and SAGE have been developing a global data base on stratospheric aerosols since they were launched in October 1978 and February 1979, respectively. The validity of this data base has been tested by numerous comparisons with other measurements made by lidars, balloon-borne particle counters, and aircraft-borne impactors and filters. Because the satellite sensors measure extinction and the correlative sensors measure other properties (e.g., backscatter, number, mass), special techniques are required to convert each measured property to other properties and to quantify conversion uncertainties and measurement uncertainties. Use of these techniques in two major comparative experiments shows that the SAM II and SAGE extinction measurements agree with each other and with values derived from dustsonde, lidar, and filter measurements. In addition, the comparative experiments have highlighted the uncertainties of each type of sensor and stimulated further efforts to reduce these uncertainties. 相似文献
917.
S D Stephens B A Watkins S S Nielsen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,20(10):1879-1889
The efficacy of using screwpress extraction for oil was studied with three Controlled Ecological Life-Support System (CELSS) candidate oilseed crops (soybean, peanut, and canola), since use of volatile organic solvents for oil extraction likely would be impractical in a closed system. Low oil yields from initial work indicated that a modification of the process is necessary to increase extraction efficiency. The extracted oil from each crop was tested for stability and sensory characteristics. When stored at 23 degrees C, canola oil and meal were least stable to oxidative rancidity, whereas peanut oil and meal were least stable to hydrolytic rancidity. When stored at 65 degrees C, soybean oil and canola meal were least stable to oxidative rancidity, whereas peanut oil and meal were least stable to hydrolytic rancidity. Sensory evaluation of the extracted oils used in bread and salad dressing indicated that flavor, odor intensity, acceptability, and overall preference may be of concern for screwpress-extracted canola oil when it is used in an unrefined form. Overall results with screwpress-extracted crude oils indicated that soybean oil may be more stable and acceptable than canola or peanut under typical storage conditions. 相似文献
918.
The means for enhancing the efficiency of rocket propulsion of spacecraft is considered in terms of the control of propellant consumption, trajectory planning, and in-flight operations management. Particular attention is given to techniques by which all the fuel and oxidizer are consumed completely by mixture adjustment as an example of a terminal control system providing significant propulsion efficiency. 相似文献
919.
The problem of measuring a constant phase difference between two sinusoids which have been corrupted by two additive noise processes is investigated. For the case in which both noise processes are Gaussian and the signal-to-noise ratio is high, the variance of the time-averaged phase-difference estimate is found as a single integral over the noise power spectral densities and cross spectral density. Arbitrary cross correlation is allowed between the two noise processes. Two cases of practical interest are considered: 1) the noise processes have identical, rectangular power spectral densities and are statistically independent; 2) an idealized radio direction finding situation in which two spatially separated sensors are immersed in an isotropic, planar noise field. For the statistically independent case, a universal curve is presented which permits determination of phase-estimate standard deviation for arbitrary signal-to-noise ratio and for a wide range of bandwidths and integration times. 相似文献
920.
We present the resuIts of manned studies in which test subjects were exposed to simulated zero g (water immersion or head-down tilt at -6 degrees) and head-to-feet acceleration. The findings give evidence that humans have different individual tolerances to an acceleration of +3 Gz after exposure to zero g, whether simulated by immersion or by head-down tilt. The paper discusses the role of functional relationship between water balance and cardiac output in the establishment of adaptive reactions to simulated zero g. 相似文献