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891.
Sunspots are the most prominent magnetic features on the Sun but it is only within the last few years that the intricate structure of their magnetic fields has been resolved. In the penumbra the fields in bright and dark filaments differ in inclination by 30°. The field in the bright filaments is less inclined to the vertical, while the field in dark filaments becomes almost horizontal at the edge of the spot. Recent models suggest that this interlocking-comb structure is maintained through downward pumping of magnetic flux by small-scale granular convection, and that filamentation originates as a convective instability. Within the bright filaments convection patterns travel radially owing to the inclination of the field. A proper understanding of these processes requires new observations, from space and from the ground, coupled with large-scale numerical modelling.  相似文献   
892.
菲利普斯曲线之中国验证——基于1985-2004年的数据分析   总被引:4,自引:0,他引:4  
本文在介绍分析菲利普斯曲线三种形态及其政策含义的基础上,使用中国的相关数据对其进行验证。本文对我国菲利普斯曲线的三种形态分别进行绘制和分析。在简要回顾对曲线走势有重要影响的宏观经济政策之后,提出当前应当逐渐由扩张性财政政策向中性的财政政策转变。  相似文献   
893.
Variations of the gravitational field affected by the Sun and the Moon while the Earth's moving along the orbit seem to be a powerful source of many rhythmical processes typical of biochemical processes. Studies carried out in AARI revealed the obvious relationships between the dynamics of some biochemical reactions and lambda(D)-function describing the regular variations of the gravitational field under combined influence of the Sun and the Moon. The following of them are examined as examples: the rate of the unithiol oxidation in vitro, concentration of the thiol compounds in human urine, some hematological indicators (rate of the erythrocytes sedimentation, hemoglobin content). Compatibility of run of the biochemical indicators and lambda(D)-function is indicative of essential influence of the regular variations of the gravitational field on rhythmics of the biochemical processes. As this takes place, the solar activity acts like to the instability factor. Balance of the solar activity effects and the varying gravitational field effect alter in time depending on location in the solar activity cycle.  相似文献   
894.
The equations of motion for the stable member of a threegimbal platform are presented [3]. These equations are combined with models of the three platform control loops to formulate a model for the system. The system model is simplified and a digital simulation is developed for studying the motion of the stable member under conditions of dynamic vehicle angular environment.  相似文献   
895.
Total absorption of hf radio waves at vertical incidence is calculated using the IRI electron density N(h) profiles at a low latitude for low and high solar activities and the calculated values of absorption are compared with the observed values. It is found that the IRI model holds good in this respect only for equinoxial months in years of low solar acitvity; however, it yields much higher values of absorption than observed during years of high solar activity (all seasons). It is suggested that seasonal anomalous variations of gas composition and bottomside thickness of the E-layer may be given due weight in revising the IRI.  相似文献   
896.
Differential Doppler measurements by a passive array are used to track an unstable continuous wave (CW) source moving in a ballistic trajectory, e.g., a projectile carrying a proximity fuse. The ballistic equations of motion couple frequency measurements at various sections along the track with the track parameters at any arbitrary time, e.g., at impact. A nonlinear weighted leastsquare method is used to estimate the track parameters, and the resulting error covariance matrix is derived. A numerical example demonstrates the relative contributions of various frequency measurements to the estimation accuracy.  相似文献   
897.
The adsorptive and/or catalytic properties of clays, silicates in general, and other minerals are well known. More recently, their probable role in prebiotic syntheses of bio-organic compounds has become a matter of record. We demonstrate that, in addition to their role in de novo formation of important biomolecules, clays, micas, fibrous silicates and other minerals mimick the activities of contemporary enzymes including oxidases, esterases, phosphatases and glucosidases. The existence of such capabilities in substances likely to be represented on the surfaces of Earth-like planets may offer a challenge to the technology and design of remote life detection systems which must then distinguish between bona fide biological chemistry and mineral-base pseudometabolism. It also raises questions about the importance of mineral surfaces in post-mortem transformations of organic metabolites in our own biosphere.  相似文献   
898.
899.
A previous analysis of order-statistics constant-false-alarm-rate (OS-CFAR) radar receiving a single pulse from a Rayleigh fluctuating target in a Rayleigh background is extended to a Rayleigh-plus-dominant target. The analysis includes effects of a multitarget environment. A detailed comparison of OS-CFAR, cell-averaging (CA) CFAR, and censored CA-CFAR is provided for a Rayleigh target in the presence of strongly interfering targets. The false-alarm analysis of OS-CFAR is extended to the more general case of a Weibull background. The deterioration of the CFAR property of OS as the shape factor, C, of a Weibull probability density function changes from Rayleigh (C=2) to a longer-tailed one (C<2) is evaluated. The analytic comparison between CA-CFAR and OS-CFAR is extended to an integration of pulses reflected from a Swerling II target. The OS-CFAR performance (with and without interfering targets) yields an integral equation that is solved numerically  相似文献   
900.
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