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Cassini-Huygens results on Titan's surface

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Chinese Journal of Astronomy and Astrophysics 2009年第3期9卷 249-268页

作者： Athena Coustenis Mathieu Hirtzig lesia Observatoire de Meudon

Our understanding of Titan, Saturn＇s largest satellite, has recently been considerably enhanced, thanks to the Cassini-Huygens mission. Since the Saturn Orbit Injection in July 2004, the probe has been harvesting new insights of the Kronian system. In particular, this mission orchestrated a climax on January 14, 2005 with the descent of the Huygens probe into Titan＇s thick atmosphere. The orbiter and the lander have provided us with picturesque views of extraterrestrial landscapes, new in composition but reassuringly Earth-like in shape. Thus, Saturn＇s largest satellite displays chains of mountains, fields of dark and damp dunes, lakes and possibly geologic activity. As on Earth, landscapes on Titan are eroded and modeled by some alien hydrology： dendritic systems, hydrocarbon lakes, and methane clouds imply periods of heavy rainfalls, even though rain was never observed directly. Titan＇s surface also proved to be geologically active - today or in the recent past - given the small number of impact craters listed to date, as well as a few possible cryovolcanic features. We attempt hereafter a synthesis of the most significant results of the Cassini-Huygens endeavor, with emphasis on the surface.

关键词： planets and satellites Titan - space vehicles

Genetic Programming-based Self-reconfiguration Planning for Metamorphic Robot

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International Journal of Automation and computing 2018年第4期15卷 431-442页

作者： Tarek Ababsa Noureddine Djedi Yves Duthen lesia Laboratory University of BiskraPO Box 145 RPBiskra 07000Algerla IRIT Laboratory University of Toulouse 1 Capitole21 Alles de BrinneToulouse 31032France

This paper presents a genetic programming based reconfiguration planner for metamorphic modular robots. Initially used for evolving computer programs that can solve simple problems, genetic programming （GP） has been recently used to handle various kinds of problems in the area of complex systems. This paper details how genetic programming can be used as an automatic programming tool for handling reconfiguration-planning problem. To do so, the GP evolves sequences of basic operations which are required for transforming the robot＇s geometric structure from its initial configuration into the target one while the total number of modules and their connectedness are preserved. The proposed planner is intended for both Crystalline and TeleCube modules which are achieved by cubical compressible units. The target pattern of the modular robot is expressed in quantitative terms of morphogens diffused on the environment. Our work presents a solution for self recontlguration problem with restricted and unrestricted free space available to the robot during reconfiguration, The planner outputs a near optimal explicit sequence of low-level actions that allows modules to move relative to each other in order to form the desired shape.

关键词： Modular robots unit-compressible modules self-reconfiguration genetic programming reconfiguration planning.

Background Activity of the Cerebral Cortex and Superficial Muscles of the Fingers in Men with Different Levels of Individual EEG a-Frequency

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Journal of Life Sciences 2013年第10期7卷 1048-1052页

作者： Morenko Alevtyna Grigorivna Pavlovych Olga Sergiyivna Kotyk Olena Adamivna Dmytrotsa Olena Romanivna Kotsan Ichor Yaroslavovych lesia Ukrainka Eastern European National University Lutsk 43001 Ukraine

A test group consisting of 104 healthy men from the ages of 19 to 21 was divided into two groups according to the magnitude of their IAF （individual EEG Gt-ffequency） median--groups with high （n = 53, IA 〉 10.04 Hz） and low （n = 51, IAF 〈 10.03 Hz） levels of IAF. Differences between the groups in terms of the power and coherence of EEG oscillations and the EMG signal average amplitude at rest were estimated. It was found that the dominant role of the thalamocortical interactions （thalamus and cortex） in the group of testees having a high IAF causes the greater differentiation and rationality of the downstream effects on muscles and provides more economic baselines and contractile capabilities of the leading hand flexor muscles. Increased non-specific influences of the limbic system and reticular formation in providing the testees＇ cortical activity under conditions of a low frequency are accompanied by a smaller lateral and reciprocal specificity in the downstream impacts, and by a lower performance of supraspinal irmervations.

关键词： Functional status of rest individual alpha-frequency EEG power and coherency muscle tone.

Shadow Volume in Real-Time Rendering

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Computer Technology and Application 2011年第8期2卷 638-643页

作者： Abd El Moumene Zerari Mohamed Chaouki Babahenini Department of Computer Science LESIA Laboratory University Med Khider Biskra Biskra 07000 Algeria

This paper presents an optimization of shadow volume algorithm, which allow a rendering in real-time. This technique is based on previous works which makes it possible to obtain shadows in real-time, although the calculation of the silhouette requires a pretreatment of the geometry implemented on the CPU (Central Processing Unit). By using last version of the GPU (Graphic Processing Unit), the authors propose to implement the calculation of the silhouette on the GPU by using Geometry Shader. The authors present the step which made it possible to lead to a concrete implementation of this algorithm, the modifications which were made, as well as a comparative study of results, followed by a discussion of these results and choices of implementation.

关键词：实时渲染阴影体积中央处理单元图形处理单元 GPU 预处理 CPU

Energy Efficiency in Periods of Load Shedding and Detrimental Effects of Energy Dependence in the City of Maroua, Cameroon

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Smart Grid and Renewable Energy 2023年第4期14卷 61-71页

作者： Ngoussandou Bello-Pierre Nicodem Nisso Dieudonné Kidmo Kaoga Kitmo Hyacinthe Tchakounté Department of Renewable Energy National Advanced School of Engineering of Maroua University of Maroua Maroua Cameroon Department of Computer Science and Telecoms National Advanced School of Engineering of Maroua University of Maroua Maroua Cameroon lesia Laboratory ENSAI University of Ngaoundere Ngaoundere Cameroon LAMSEBP Laboratory University of Yaoundé I Yaoundé Cameroon

During the years 2021 and 2022, the city of Maroua experienced repeated power blackouts. However, this locality has significant photovoltaic energy potential. Nevertheless, the evaluation of the electrical performance showed the dependence of the population on these fluctuations, which could be bypassed or suppressed. In most cases, the blackout occurs during high energy demand. In this paper, a method for evaluating electrical efficiency is proposed and its credibility has been demonstrated on the one hand, and on the other hand, a renewable energy production system is proposed. The Homer software has made possible the analysis of the proposed system and its impact on the environment has also been carried out. The techno-economic study of the system has proved that a solar photovoltaic farm associated with an energy storage system, with a capacity of 47 MW, can meet the energy demand of the town of Maroua. This alternative is profitable for this locality which lives in a precarious situation and a continuous need.

关键词： Energy Efficiency Load Shedding Detrimental Effects Maroua Cameroon

Analysis of equilibria in the doubly synchronous binary asteroid systems concerned with non-spherical shape

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Astrodynamics 2018年第2期2卷 133-146页

作者： Xiangyu Li Dong Qiao M.A.Barucci School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Key Laboratory of Autonomous Navigation and Control for Deep Space Exploration Ministry of Industry and Information TechnologyBeijing 100081China Paris Observatory LESIA5Place J.Janssen92195 Meudon Principal CedexFrance

This paper investigates the equilibria and their stabilities in the doubly synchronous binary asteroid systems,which are modelled as the two tri-axial ellipsoids with various shape and system ***,the influences of shape and system parameters on equilibria are discussed ***,the geometrical models of doubly synchronous binary asteroid systems are *** dual second degree and order gravity fleld is employed to approximate the gravitational potential of the *** shape and system parameters are ***,based on the linearized perturbation equations,the explicit expressions of the offsets of equilibria in doubly synchronous systems are derived,which clearly ilustrate the relationship between the distribution of equilibria and the variations of shape ***,the approximate expressions are applied to estimate the ftets of equilibria due to parameter etrors,***,in order to have a better insight into the equilibriaum structure,the sabiltis of equilibrisa under diferent system parameters are *** particular,critical regions of triangular equilibria are calculated and the role of the relative distance on the stability is discussed in *** study could provide a preliminary analysis of equilibria for the mission design in doubly synchronous binary asteroid systems.

关键词： doubly synchronous binary asteroid equilibria non-spherical shape stability

Comment on “Locating the source field lines of Jovian decametric radio emissions” by YuMing Wang et al.

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Earth and Planetary Physics 2022年第1期6卷 10-12页

作者： Laurent Lamy Baptiste Cecconi Stéphane Aicardi C.K.Louis lesia Observatoire de ParisUniversitéPSLCNRSSorbonne UniversitéUniversitéde Paris5 place Jules Janssen92195 MeudonFrance Station de Radioastronomie de Nançay Observatoire de ParisUniversitéPSLCNRSUniv.Orléans18330 NançayFrance LAM PythéasAix Marseille UniversitéCNRSCNES38 Rue Frédéric Joliot Curie13013 MarseilleFrance DIO UMS2201 CNRSObservatoire de ParisUniversitéPSL61 avenue de l’Observatoire75014ParisFrance School of Cosmic Physics DIAS Dunsink ObservatoryDublin Institute for Advanced StudiesDublinIreland

In this comment on the article“Locating the source field lines of Jovian decametric radio emissions”by Wang YM et al.,2020,we discuss the assumptions used by the authors to compute the beaming angle of Jupiter’s decametric emissions induced by the moon *** method,relying on multi-point radio observations,was applied to a single event observed on 14th March 2014 by Wind and both STEREO A/B spacecraft from~5 to~16 *** have erroneously identified the emission as a northern(Io-B type)instead of a southern one(Io-D type).We encourage the authors to update their results with the correct hemisphere of origin and to test their method on a larger sample of Jupiter-Io emissions.

关键词： planetary magnetosphere Jupiter auroral radio emissions planet-moon interaction

A Multi-Wavelength Study of the 3B/X1.2 Flare Observed on 2003 October 26

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Chinese Journal of Astronomy and Astrophysics 2005年第6期5卷 645-664页

作者： Hui Li Jian-Ping Li Cheng Fang Brigitte Schmieder Arkadiusz Berlicki Qiu-Sheng Du Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 Department of Astronomy Nanjing University Nanjing 210093 Observatoire de Paris Section de Meudon LESIA i~-9-2195 Meudon Principal CedexFrance Institute of Theoretical Astrophysics University of Oslo Blindern N-0315 Oslo Norway Astronomical Institute of the Wroctaw University ul.Kopernika 11 51-622 Wroctaw Poland

We report results from a multi-wavelength study of the 3B/X1.2 tworibbon disk flare （S15E44）, which was well observed by both ground-based and space-borne instruments. Two pairs of conjugate kernels - K1 and K4, and K2 and K3 - in the Ha images are identified. These kernels are linked by two different systems of EUV loops. K1 and K4 correspond to the two 17 GHz and 34 GHz microwave sources observed by the Nobeyama Radioheliograph （NoRH）, while K2 and K3 have no corresponding microwave sources. Optical spectroscopic observations suggest that all the four kernels are possible precipitating sites of non-thermal electrons. Thus the energy of electron deposited in K2 and K3 should be less than 100keV. Two-dimensional distributions of the full widths at half maximum （FWHM） of the Ha profiles and the line-of-sight （LOS） velocities derived from the Ca n 8542 A profiles indicate that the largest FWHM and LOS velocity tends to be located near the outer edges of Hα kernels, which is consistent with the scenario of current two-ribbon flare models and previous results. When non-thermal electron bombardment is present, the observed Hα and Ca II 8542 A profiles are similar to previous observational and theoretical results, while the He I 10830 A profiles are different from the theoretical ones. This puts some constraints on future theoretical calculation of the He I 10830 A line.

关键词： Sun flares - Sun X-rays - line profiles

Hybrid Successive CFA Image Encryption-Watermarking Algorithm Based on the Quaternionic Wavelet Transform (QWT)

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Journal of Information Security 2022年第4期13卷 244-256页

作者： Hervé Abena Ndongo Marcelin Vournone Mireille Pouyap Taya Ngakawa Paul Abena Malobe Energy Signal Imaging and Automatic Laboratory (LESIA) Department of Electrical and Industrial Automatic Engineering National School of Agro-Industrial Sciences (ENSAI) University of Ngaoundere Ngaoundere Cameroon Mapping Production Division Department of Data Collection National Institute of Cartography Yaounde Cameroon Department of Physics Higher Teacher Training College University of Maroua Maroua Cameroon Department of Physics Faculty of Science (FS) University of Ngaoundere Ngaoundere Cameroon

In this paper, we present a new robust hybrid algorithm combining successively chaotic encryption and blind watermarking of images based on the quaternionic wavelet transform (QWT) to ensure the secure transfer of digital data. The calculations of the different evaluation parameters have been performed in order to determine the robustness of our algorithm to certain attacks. The application of this hybrid algorithm on CFA (Color Filter Array) images, allowed us to guarantee the integrity of the digital data and to propose an autonomous transmission system. The results obtained after simulation of this successive hybrid algorithm of chaotic encryption and then blind watermarking are appreciated through the values of the evaluation parameters which are the peak signal-to-noise ratio (PSNR) and the correlation coefficient (CC), and by the visual observation of the extracted watermarks before and after attacks. The values of these parameters show that this successive hybrid algorithm is robust against some conventional attacks.

关键词： Encryption Blind Watermarking Chaos CFA Images QWT