排序方式： 共有23条查询结果，搜索用时 31 毫秒
11.
Yu. V. Pakhomov K. A. Antonyuk N. I. Bondar’ N. V. Pit’ I. V. Reva A. V. Kusakin 《Astronomy Letters》2018,44(1):35-48
Based on our photometric observations in 2015–2016 and archival photometric data for the active red giant PZ Mon, we have found the main characteristics of the stellar surface: the unspotted surface temperature Teff = 4730 K, the spot temperature Ts = 3500 K, and the relative spot area from 30 to 40%. The best agreement with the observations has been achieved in our three-spot model including a cool polar spot with a temperature of ~3500 K as well as large and small warm spots with a temperature of ~4500 K. The stable polar spot is responsible for the long-period brightness variations. Its presence is confirmed by an analysis of the TiO 7054 Å molecular band. The small-amplitude 34-day variability is attributable to the warm spots located on the side of the secondary component, which determine the relatively stable active longitude. 相似文献
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Anton Reva Artem Ulyanov Alexey Kirichenko Sergey Bogachev Sergey Kuzin 《Solar physics》2018,293(10):140
Nanoflare-heating theory predicts steady hot-plasma emission in non-flaring active regions. It is hard to find this emission with conventional non-monochromatic imagers (such as the Atmospheric Imaging Assembly or the X-Ray Telescope), because their images contain a cool-temperature background. In this work, we search for hot plasma in non-flaring active regions using the Mg?xii spectroheliograph onboard the Complex Orbital Observations Near-Earth of Activity on the Sun (CORONAS)-F/SPectroheliographIc X-ray Imaging Telescope (SPIRIT). This instrument acquired monochromatic images of the solar corona in the Mg?xii 8.42 Å line, which emits only at temperatures higher than 4 MK. The Mg?xii images only contain the signal from hot plasma, without any low-temperature background. We studied the hot plasma in active regions using SPIRIT data from 18?–?28 February 2002. During this period, the Mg?xii spectroheliograph worked with a 105-second cadence almost without data gaps. Hot plasma was observed only in the flaring active regions. We did not observe any hot plasma in non-flaring active regions. The hot-plasma column emission measure in the non-flaring active region is not expected to exceed \(3 \times10^{24}\) cm?5. The hot differential emission measure is lower than 0.01% of the DEM of the main temperature component. The absence of Mg?xii emission in the non-flaring active regions can be explained by weak and frequent nanoflares (with a delay of less than 500 seconds) or by very short and intense nanoflares that lead to non-equilibrium ionization. 相似文献
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S. V. Kuzin S. V. Shestov S. A. Bogachev A. A. Pertsov A. S. Ulyanov A. A. Reva 《Solar System Research》2011,45(2):174-181
In January 2009, the CORONAS-PHOTON spacecraft was successfully launched. It includes a set of telescopes and spectroheliometers—TESIS—designed
to image the solar corona in soft X-ray and EUV spectral ranges. Due to features of the reading system, to obtain physical
information from these images, it is necessary to preprocess them, i.e., to remove the background, correct the white field,
level, and clean. The paper discusses the algorithms and software developed and used for the preprocessing of images. 相似文献
14.
S. V. Kuzin I. A. Zhitnik S. V. Shestov S. A. Bogachev O. I. Bugaenko A. P. Ignat’ev A. A. Pertsov A. S. Ulyanov A. A. Reva V. A. Slemzin N. K. Sukhodrev Yu. S. Ivanov L. A. Goncharov A. V. Mitrofanov S. G. Popov T. A. Shergina V. A. Solov’ev S. N. Oparin A. M. Zykov 《Solar System Research》2011,45(2):162-173
On February 26, 2009, the first data was obtained in the TESIS experiment on the research of the solar corona using imaging spectroscopy. The TESIS is a part of the scientific equipment of the CORONAS-PHO-TON spacecraft and is designed for imaging the solar corona in soft X-ray and extreme ultraviolet regions of the spectrum with high spatial, spectral, and temporal resolutions at altitudes from the transition region to three solar radii. The article describes the main characteristics of the instrumentation, management features, and operation modes. 相似文献
15.
Interactive 3D geo-browsers, also known as globe viewers, are popular, because they are easy and fun to use. However, it is still an open question whether highly interactive, 3D geographic data browsing, and visualization displays support effective and efficient spatio-temporal decision making. Moreover, little is known about the role of time constraints for spatio-temporal decision-making in an interactive, 3D context. In this article, we present an empirical approach to assess the effect of decision-time constraints on the quality of spatio-temporal decision-making when using 3D geo-browsers, such as GoogleEarth, in 3D task contexts of varying complexity. Our experimental results suggest that while, overall, people interact more with interactive geo-browsers when not under time pressure, this does not mean that they are also more accurate or more confident in their decisions when solving typical 3D cartometric tasks. Surprisingly, we also find that 2D interaction capabilities (i.e., zooming and panning) are more frequently used for 3D tasks than 3D interaction tools (i.e., rotating and tilting), regardless of time pressure. Finally, we find that background and training of tested users do not seem to influence 3D task performance. In summary, our study does not provide any evidence for the added value of using interactive 3D globe viewers when needing to solve 3D cartometric tasks with or without time pressure. 相似文献
16.
Mapping climatic temperature changes in the ocean with acoustictomography: navigational requirements
Spiesberger J.L. Fabrikant A.L. Silivra A.A. Hurlburt H.E. 《Oceanic Engineering, IEEE Journal of》1997,22(1):128-142
In eddy-resolving hydrodynamic models, first-mode baroclinic Rossby waves linked to El Nino/Southern Oscillation are the dominant features which change basin-wide temperatures below the seasonal thermocline in the northeast Pacific at periods less than a decade. Simulations are carried out in which Rossby waves are mapped using acoustic tomography. Based on the model which propagated these waves, a Kalman filter is used to map temperature signals for a year. The modeled data are taken from a dense network of acoustic tomography sections. At 300-m depth, where the temperature perturbations associated with Rossby waves are about ±1°C, 80% to 90% of the model variance is accounted for with tomographic estimates. The corresponding standard deviations of the estimates are less than 0.1°C at 400-km resolution. About 80% of the model variance is accounted for with tomography when the navigational errors of the sources and receivers are as poor as one kilometer. Consequently, it may be unnecessary to accurately navigate actual tomographic instruments to map climate change. Modeling results are insensitive to: 1) a reduction in data due to a significant number of instruments which fail; 2) whether the instruments are mobile or fixed; 3) the detailed trajectories of mobile receivers; 4) the shape of the a priori spectrum of ocean fluctuations; 5) the corrections to the acoustic travel-time biases; and 6) the errors in the sound-speed algorithm. In basin-scale arrays, the modeled variance of acoustic travel time depends on the horizontal wavenumber of temperature as k-5.5. Because sound has little sensitivity to small wavelengths, modeled Rossby waves can be mapped in a day from a few sources and of order ten receivers. The results only depend on the model having large scales in space and time 相似文献
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The Hyades Cluster is used to analyze details of the AD-diagram method developed in our earlier works and applied to the corona of the Ursa Major stream. Hipparcos data are used to analyze the kinematics of the Hyades Cluster and determine its apex. Evidence for rotation of the cluster is presented. 相似文献
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An empirical evaluation of three elevation change symbolization methods along routes in bicycle maps
ABSTRACTElevation change is critical for choosing a route when bicycling. We detail an empirical study in which we comparatively evaluated three linear symbolization types (color hue, color-coded arrows, and elevation profiles) to depict elevation change in bicycle maps for two common bicycle route planning tasks: relative height detection and slope identification. Participants performed most accurately with the color-coded arrows for relative height detection tasks, whereas symbolization did not significantly influence map-use performance for slope identification. Participants preferred the elevation profile, in spite of their lowest performance with this method overall. Our rare empirical findings offer much needed new insights into the function and appropriateness of common elevation symbolization methods, specifically to identify elevation change in bicycle route planning tasks in urban areas where map display real estate is already very limited. 相似文献