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1.
U. C. Joshi A. K. Sen M. R. Deshpande J. S. Chauhan 《Journal of Astrophysics and Astronomy》1992,13(3):267-277
Photopolarimetric observations of comet Austin with the IAU/IHW filter system were obtained on the 2.34 m Vainu Bappu Telescope
(VBT) of the Indian Institute of Astrophysics, at Kavalur, India, during pre-perihelion phase on February 20,1990 and on the
1.2 m telescope of the Physical Research Laboratory at Gurusikhar, Mount Abu during postperihelion phase on May 2 and 4, 1990.
The comet appeared bluer than a solar analog during post-perihelion phase on May 2 and 4. The percent polarization shows a
sharp increase towards the red on May 2 and 4. The dominant sizes of the dust particles appear to lie in a narrow range of
0.1 to 0.5 Μm. Regarding the molecular band emission, CN and C2 bands are quite strong; C3 emission was also found to be strong though the observations on May 2 and 4 show significant variation as compared to C2 emission. Molecular band polarization for CN, C3, C2 and H2 O+ have been calculated. It has been found that emission polarization in CN, C2 and C3 is between 1–7% (phase angle between 107.4–109 degrees). For CN and C2 the polarization values are close to the theoretically predicted values, but for C3 the polarization value falls much below the theoretically predicted value. A similar result was found for comet Halley. 相似文献
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3.
This paper presents an on-line trained neural net work controller for ship track-keeping problems. Following a brief review of the ship track-keeping control development since the 1980's, an analysis of various existing backpropagation-based neural controllers is provided. We then propose a single-input multioutput (SIMO) neural control strategy for situations where the exact mathematical dynamics of the ship are not available. The aim of this study is to build an autonomous neural controller which uses rudder to regulate both the tracking error and heading error. During the whole control process, the proposed SIMO neural controller adapts itself on-line from a direct evaluation of the control accuracy, and hence the need for a “teacher” or an off-line training process can be removed. With a relatively modest amount of quantitative knowledge of the ship behavior, the design philosophy enables real time control of a nonlinear ship model under random wind disturbances and measurement noise. Three different track-keeping tasks have been simulated to demonstrate the effectiveness of the training method and the robust performance of the proposed neural control strategy 相似文献
4.
宣森 《广东海洋大学学报》1993,(1)
将专家系统技术与常规控制、模糊控制、超前控制、仿人智能操作控制以及计算机控制技术相结合,设计了一种新的基于专家系统决策的多模式控制(MCDBES)。经试验和实际运行结果表明,MCDBES系统对未知数学模型的被控对象,具有良好的控制性能。本文提出的MCDBES已成功地应用于燃油陶瓷窑炉计算机控制系统。 相似文献
5.
In many astrophysical problems, the study of the stability of an atmosphere in the presence of a magnetic field is of importance. In most cases the MHD instabilities of atmospheres are studied by energy principle of Bernsteinet al. (1958). In this paper, a general method for studying the stability of a system subject to MHD equations of conditions has been proposed. This is based on the local potential concept put forward by Glansdorff and Prigogine (1964). The scheme for securing stability criteria has been demonstrated in two particular cases. 相似文献
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INTRODUCTIONTheSubeiShoalandtheChangjiangRiverestuarineareainthewestoftheHuanghaiandEastChinaSeasisoneofthemarginalseasintheworld ,wheresuspendedmatterisextremelyhigh .Here ,notonlyistheretheTaiwanWarmCurrentoneoftheKuroshio’sbranchesintheEastChinaSea,butalsotheHuanghaiCoastalCurrent,andChangjiangDilutedWater.Sothestrongmixingbetweenthecoastalandoffshorewaterscomplicatessuspendedmatterdistributioninthisarea.HowthesuspendedmatterdischargedfromtheChangjiangRiverandtheabandonedHuan… 相似文献
8.
X. Bai T.K. Gaisser A. Karle K. Rawlins G.M. Spiczak Todor Stanev 《Astroparticle Physics》2006,25(6):361-367
The muon flux at the South Pole was measured for five zenith angles, 0°, 15°, 35°, 82.13° and 85.15° with a scintillator muon telescope incorporating ice Cherenkov tank detectors as the absorber. We compare the measurements with other data and with calculations. 相似文献
9.
An Example of Island-Arc Petrogenesis: Geochemistry and Petrology of the Southern Luzon Arc, Philippines 总被引:7,自引:1,他引:6
DEFANT MARC J.; MAURY REN? C.; RIPLEY EDWARD M.; FEIGENSON MARK D.; JACQUES DARIO 《Journal of Petrology》1991,32(3):455-500
Volcanism throughout the Luzon arc is associated with eastwardsubduction of the South China Sea floor along the Manila Trench.The southern section of the arc, the focus of this study, extendsfrom the Lingayen-Dingalan fault to the small islands just southof Luzon. Two segments appear to exist along this section ofthe arc the northern Bataan and southern Mindoro segments whichare separated by the Macolod Corridor. The volcanic rocks have typical arc phenocryst mineralogies:olivine, clinopyroxene, plagioclase, and titanomagnetite inthe most mafic rocks and clinopyroxene, plagioclase, orthopyroxene,titanomagnetite, ? amphibole in the more felsic samples. Complexzoning, sieve textures, and decoupling of incompatible traceelements suggest that processes such as assimilation have takenplace. The rocks from the study area range from basalts to rhyolitesand show typical calc-alkaline features. The rocks of the MacolodCorridor and Mindoro segment are particularly enriched in largeion lithophile elements (LILE), light rare earth elements (LREE),and radiogenic Sr compared with the Bataan segment. The datafall within the mantle array on Sr-Nd isotopic diagrams andgrade toward higher Sr and lower Nd isotopic values from northto south. A likely source for the volcanics of this study is either amid-ocean ridge basalt (MORB)-type mantle that undergoes higherdegrees of partial melting than regions involved in MORB generationor a previously depleted source. We suggest that the high fieldstrength element (HFSE) anomalies have been derived throughdifferential element partitioning during fluid transport fromthe subducted lithosphere to the mantle wedge. Continental crustal material seems to play a significant roleparticularly in the Macolod Corridor and the Mindoro segment,based on the high LILE, La/Sm ratios, radiogenic Sr isotopes,and 18O values. The Macolod Corridor and the Mindoro segmenthave undergone source contamination by crustal material fromthe North Palawan-Mindoro crustal block either during the collisionof this block with the Manila Trench or by subduction of sedimentsrich in this crustal material. A similar component has alsobeen detected in the Bataan segment but in minor amounts. Thetrace element and isotopic differences between the northernand southern sections of the arc are interpreted in terms ofvariable composition (i. e., variable amounts of a crustal componentintroduced from the Palawan-Mindoro crustal terrain) of themetasomatic fluids released into the source. 相似文献
10.