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891.
W. I. Axford J. F. McKenzie G. V. Sukhorukova M. Banaszkiewicz A. Czechowski R. Ratkiewicz 《Space Science Reviews》1999,87(1-2):25-41
We outline a theory for the origin and acceleration of the fast solar wind as a consequence of network microflares releasing
a spectrum of high frequency Alfvén waves which heat (by cyclotron absorption) the corona close to the Sun. The significant
features of our model of the fast wind are that the acceleration is rapid with the sonic point at around two solar radii,
the proton temperatures are high (~ 5 million degrees) and the minor ions are correspondingly hotter, roughly in proportion
to their mass. Moreover we argue that since the energy flux needed to power the quiet corona in closed field regions is about
the same as that needed to drive the fast solar wind, and also because at deeper levels (< 2 × 105 K) there is no great difference in the properties of supergranules and network in closed and open field regions, the heating
process (i.e., dissipation of high frequency waves) must be the same in both cases.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
892.
893.
V.B. Betelin N.N. Smirnov V.F. Nikitin V.R. Dushin A.G. Kushnirenko V.A. Nerchenko 《Acta Astronautica》2012
Computer simulation of liquid fuel jet injection into heated atmosphere of combustion chamber, mixture formation, ignition and combustion need adequate modeling of evaporation, which is extremely important for the curved surfaces in the presence of strong heat and mass diffusion fluxes. Combustion of most widely spread hydrocarbon fuels takes place in a gas-phase regime. Thus, evaporation of fuel from the surface of droplets turns to be one of the limiting factors of the process as well. The problems of fuel droplets atomization, evaporation being the key factors for heterogeneous reacting mixtures, the non-equilibrium effects in droplets atomization and phase transitions will be taken into account in describing thermal and mechanical interaction of droplets with streaming flows. In the present paper processes of non-equilibrium evaporation of small droplets will be discussed. As it was shown before, accounting for non-equilibrium effects in evaporation for many types of widely used liquids is crucial for droplet diameters less than 100 μm, while the surface tension effects essentially manifest only for droplets below 0.1 μm. Investigating the behavior of individual droplets in a heated air flow allowed to distinguish two scenarios for droplet heating and evaporation. Small droplets undergo successively heating, then cooling due to heat losses for evaporation, and then rapid heating till the end of their lifetime. Larger droplets could directly be heated up to a critical temperature and then evaporate rapidly. Droplet atomization interferes the heating, evaporation and combustion scenario. The scenario of fuel spray injection and self-ignition in a heated air inside combustion chamber has three characteristic stages. At first stage of jet injection droplets evaporate very rapidly thus cooling the gas at injection point, the liquid jet is very short and changes for a vapor jet. At second stage liquid jet is becoming longer, because evaporation rate decreases due to decrease of temperature. But combustion of fuel vapor begins which brings to increase of heat flux to droplets and accelerates evaporation. The length of the liquid jet decreases again and remains constant slightly oscillating. 相似文献
894.
J F Bottollier-Depois F Spurny L Plawinski I Votockova J Bednar M Viso A Labarthe 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1998,22(4):517-520
The dosimetry of cosmic rays was performed during the first experimental flight of the IBIS facility. Different thermoluminescent detectors (TLD) have been used to measure the contribution of the low linear energy transfer component (LET < 10 keV/micrometer) and plastic nuclear track detectors (PNTD) for the high linear energy tranfer (LET) component. Several parameters of tracks have been measured to determine the LET spectra of primary and secondary charged particles. The total absorbed dose rate (TLD+PNTD) during the flight was 0.23 mGy/day and the dose equivalent rate using the ICRP 60 was 0.52 mSv/day. The corresponding mean quality factor was 2.4. These results are in agreement with those obtained aboard the MIR station with a tissue equivalent proportional counter. 相似文献
895.
An overview of the key operational and technical factors governing future radar evolution is given, in order to identify main lines along which research and development effort should be oriented 相似文献
896.
I. V. Mingalev N. M. Astaf’eva K. G. Orlov V. M. Chechetkin V. S. Mingalev O. V. Mingalev 《Cosmic Research》2012,50(3):233-248
Mechanisms of formation of cyclonic vortices in the tropical atmosphere of the Earth are investigated in the intratropical
zone of convergence using numerical simulation made with the complete system of equations of gas dynamics taking into account
transport of infrared radiation, phase transitions of water vapor into microdrops of water and ice particles, and sedimentation
of these drops and ice particles in the field of gravity force. Observational data on the structure of dominant air streams,
which are formed in the intratropical zone of convergence over the North Atlantic in the periods of its highest thermodynamic
intensity and instability, are used in the initial and boundary conditions of the model. Formation of cyclonic vortex flows
is obtained numerically at sufficiently strong bending of the intratropical zone of convergence. The results of numerical
modeling are compared with the data of satellite microwave monitoring: global radio thermal fields of the Earth from the electronic
collection GLOBAL-Field allowing one to study the structure of atmospheric motions in a wide range of space-time scales. 相似文献
897.
Statistical studies of properties of the solar wind and interplanetary magnetic field, based on an extended database for the
period 1963–2007 including four solar cycles, show that the Gaussian approximation well suites for some parameters as the
probability distribution of their numerical values, while for others the lognormal law is preferred. This paper gives an interpretation
of these results as associated with predominance of linear or nonlinear processes in composition and interaction of various
disturbances and irregularities propagating and originating in the interior of the Sun and its atmosphere, including the solar
corona and the solar wind running away from it. Summation of independent random components of disturbances leads, according
to the central limit theorem of the probability theory, to the normal (Gaussian) distributions of quantities proper, while
their multiplication leads to the normal distributions of logarithms. Thus, one can discuss the algebra of events and associate
observed statistical distinctions with one or another process of formation of irregularities in the solar wind. Among them
there are impossible events (having null probability) and reliable events (occurring with 100% probability). For better understanding
of the relationship between algebra and statistics of events in the solar wind further investigations are necessary. 相似文献
898.
Test instrumentation is described for use in the measurement of threshold sensitivities and noise bandwidths of narrow-band phase-locked receivers. The method is statistical in nature with the data being recorded digitally by a counter and printer. Scale factors can be selected for convenient relation of the data to the standard deviations, 1,2, or 3 sigma. Curves are included showing the results of a typical experiment. 相似文献
899.
V. G. Vil’ke 《Cosmic Research》2010,48(3):273-282
A mechanical system consisting from N deformable spheres interacting according to the law of gravity is considered as a model of planetary system. Deformations
of the viscoelastic spheres are described according to the model of the theory of elasticity of small deformations, the Kelvin-Voigt
model of viscous forces, and occur under the action of gravitational fields and fields of centrifugal forces. Approximate
equations describing motions of the centers of mass of the spheres and their rotations relative to the centers of mass are
constructed by the method of separation of motions on the basis of solving quasistatic problems of the theory of viscoelasticity
with allowance made for smallness of sphere deformations. Using the first integral of conservation of the angular momentum
of the system relative to its center of mass, the expression for the changed potential energy is obtained with the use of
the Routh method. An investigation of stationary rotations is carried out, and it is shown that all of them are unstable,
if the number of planets is more than two. 相似文献
900.
P.R. Gazis F.B. McDonald R.A. Burger S. Chalov R.B. Decker J. Dwyer D.S. Intriligator J.R. Jokipii A.J. Lazarus G.M. Mason V.J. Pizzo M.S. Potgieter I.G. Richardson L.J. Lanzerotti 《Space Science Reviews》1999,89(1-2):269-305
We discuss the structure and evolution of CIRs and their successors in the outer heliosphere. These structures undergo significant
evolution as they are convected to greater heliocentric distances. A progression of different types of structure are observed
at increasing distance from the Sun. Similar structures are observed at similar heliocentric distance at different portions
of the solar cycle. CIRs and their successors are associated with many important physical processes in the outer heliosphere.
We discuss the relationship between these structures and recurrent phenomena such as cosmic ray variations, and review some
of the associated theoretical models on the role of corotating structures and global merged interaction regions (GMIRs) in
global cosmic ray modulation. We also discuss some outstanding questions related to the origin of non-dispersive quasi-periodic
particle enhancements associated with CIRs and their successors in the outer heliosphere.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献