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1.
The successful realisation of the flagship programmes, Galileo/EGNOS and GMES has been in doubt as a result of the current financial constraints. In providing an overview of the role of these two programmes in relation to implementing European policies – with sector-by-sector information on the ways they can help fulfil specific EU objectives – this paper attempts to demonstrate why and how they must be successfully operationalised. It therefore continues by analysing their political, economic, social, technological, environmental and legal strengths and weaknesses and makes policy recommendations on this basis. Utilising these flagship programmes to carry through major European policies will be crucial for realising their great potential and achieving the Europe 2020 goals of the European Union.  相似文献   
2.
Multi-reflected echoes (MREs) and satellite traces (STs) are referred in literature as ionogram signatures of Travelling Ionospheric Disturbances (TIDs) which is a phenomenon that apparently drives spread F development mainly at nighttime mid-latitude ionosphere. A long-term statistical study has been undertaken to investigate the morphological aspect of these signatures over the lower midlatitude European station of Nicosia, Cyprus (35.19°N, 33.38°E geographic; magnetic dip. 29.38°N) by inspecting all ionograms recorded by the DPS-4D digisonde in the interval 2009–2016. The results underline the systematic manifestation of these TID signatures over Cyprus with a possible (although not quite clear) solar activity dependence and a distinctive seasonal and diurnal occurrence rate with a seasonal peak of STs during summer and of MREs during January to April. Based on the experimental results of the present study, the seasonal occurrence rate of MREs and STs is found to increase by 75% and 56% during high solar activity periods. Satellite traces are well known ionogram signatures of TIDs and mostly correlated to the nighttime spread F formation. The occurrence of mid-latitude spread Fs over European longitude sector normally increases during summer. The occurrences of TIDs are also prominent at this interval of the year over nighttime mid-latitude ionosphere. The presence of MREs as an ionogram signature of TIDs over mid-latitude ionosphere is unique in nature.  相似文献   
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We examine the systematic differences between topside electron density measurements recorded by different techniques over the low-middle latitude operating European station in Nicosia, Cyprus (geographical coordinates: 35.14oN, 33.2oE), (magnetic coordinates 31.86oN, 111.83 oE). These techniques include space-based in-situ data by Langmuir probes on board.European Space Agency (ESA) Swarm satellites, radio occultation measurements on board low Earth orbit (LEO) satellites from the COSMIC/FORMOSAT-3 mission and ground-based extrapolated topside electron density profiles from manually scaled ionograms. The measurements are also compared with International Reference Ionosphere Model (IRI-2016) topside estimations and IRI-corrected NeQuick topside formulation (method proposed by Pezzopane and Pignalberi (2019)). The comparison of Swarm and COSMIC observations with digisonde and IRI estimations verifies that in the majority of cases digisonde underestimates while IRI overestimates Swarm observations but in general, IRI provides a better topside representation than the digisonde. For COSMIC and digisonde profiles matched at the F layer peak the digisonde systematically underestimates topside COSMIC electron density values and the relative difference between COSMIC and digisonde increases with altitude (above hmF2), while IRI overestimates the topside COSMIC electron density but after a certain altitude (~150 km above hmF2) this overestimation starts to decrease with altitude. The IRI-corrected NeQuick underestimates the majority of topside COSMIC electron density profiles and relative difference is lower up to approximately 100 km (above the hmF2) and then it increases. The overall performance of IRI-corrected NeQuick improves with respect to IRI and digisonde.  相似文献   
5.
The Rosetta spacecraft has been successfully launched on 2nd March 2004 to its new target comet 67 P/Churyumov-Gerasimenko. The science objectives of the Rosetta Radio Science Investigations (RSI) experiment address fundamental aspects of cometary physics such as the mass and bulk density of the nucleus, its gravity field, its interplanetary orbit perturbed by nongravitational forces, its size and shape, its internal structure, the composition and roughness of the nucleus surface, the abundance of large dust grains, the plasma content in the coma and the combined dust and gas mass flux. The masses of two asteroids, Steins and Lutetia, shall be determined during flybys in 2008 and 2010, respectively. Secondary objectives are the radio sounding of the solar corona during the superior conjunctions of the spacecraft with the Sun during the cruise phase. The radio carrier links of the spacecraft Telemetry, Tracking and Command (TT&C) subsystem between the orbiter and the Earth will be used for these investigations. An Ultrastable oscillator (USO) connected to both transponders of the radio subsystem serves as a stable frequency reference source for both radio downlinks at X-band (8.4 GHz) and S-band (2.3 GHz) in the one-way mode. The simultaneous and coherent dual-frequency downlinks via the High Gain Antenna (HGA) permit separation of contributions from the classical Doppler shift and the dispersive media effects caused by the motion of the spacecraft with respect to the Earth and the propagation of the signals through the dispersive media, respectively. The investigation relies on the observation of the phase, amplitude, polarization and propagation times of radio signals transmitted from the spacecraft and received with ground station antennas on Earth. The radio signals are affected by the medium through which the signals propagate (atmospheres, ionospheres, interplanetary medium, solar corona), by the gravitational influence of the planet on the spacecraft and finally by the performance of the various systems involved both on the spacecraft and on ground.  相似文献   
6.
In plants, sensitive and selective mechanisms have evolved to perceive and respond to light and gravity. We investigated the effects of microgravity on the growth and development of Arabidopsis thaliana (ecotype Landsberg) in a spaceflight experiment. These studies were performed with the Biological Research in Canisters (BRIC) hardware system in the middeck region of the space shuttle during mission STS-131 in April 2010. Seedlings were grown on nutrient agar in Petri dishes in BRIC hardware under dark conditions and then fixed in flight with paraformaldehyde, glutaraldehyde, or RNAlater. Although the long-term objective was to study the role of the actin cytoskeleton in gravity perception, in this article we focus on the analysis of morphology of seedlings that developed in microgravity. While previous spaceflight studies noted deleterious morphological effects due to the accumulation of ethylene gas, no such effects were observed in seedlings grown with the BRIC system. Seed germination was 89% in the spaceflight experiment and 91% in the ground control, and seedlings grew equally well in both conditions. However, roots of space-grown seedlings exhibited a significant difference (compared to the ground controls) in overall growth patterns in that they skewed to one direction. In addition, a greater number of adventitious roots formed from the axis of the hypocotyls in the flight-grown plants. Our hypothesis is that an endogenous response in plants causes the roots to skew and that this default growth response is largely masked by the normal 1?g conditions on Earth.  相似文献   
7.
This paper deals with the attitude control performance analysis of a square solar sail. Two sliding masses are moved inside and along mast lanyards for the control around the pitch and yaw axes. An optimal linear controller with a feedback and a feedforward part is used to control the attitude of the sail. Numerical simulations have been carried out to investigate the system’s ability of performing precise and near-time-optimal reorientation maneuvers as well as the controller’s sensitivity with respect to the sail parameters, as the center of pressure to the center of mass offset or the sail’s size. Our simulation results are finally shown and discussed.  相似文献   
8.
There is little overview of how space applications are utilized by African actors and how cooperation between Africa and Europe is organized and conducted. This article aims briefly to provide such an overview and concretely to make recommendations for institutional actors in European-African partnerships on the use of space applications for sustainable development. The Africa-EU partnership is analysed from a political, economic, social, technological, environmental and legal standpoint and respective policy recommendations are drafted on this basis. No other continent can benefit more from space applications than Africa. It will be partnerships like the one between Europe and Africa that will be crucial for realizing this great potential.  相似文献   
9.
候鸟 《今日民航》2009,(4):88-89
人物简介:周德,台湾人,司马克斯高尔夫设计策划有限公司首席设计师,北京加州水郡高尔夫球会总经理。著名的球场设计、建造、管理专家。从事高尔夫行业二十余年,在球场设计与建造、球会运营管理、球童培训、草坪维护方面拥有丰富经验。近年在国内相继设计、建造了银川黄河(湿地)高尔夫球场、北京加州水郡高尔夫球场。秉承保护自然、恢复原始风华的设计理念,就球场的地域风貌、自然生态、经营规划等多方因素综合考量,将高尔夫的文化和艺术与生态环境建设融合一体。  相似文献   
10.
This paper analyses the growing involvement of the European Defence Agency (EA) in the field of space, suggesting that this is symptomatic of the greater importance now being placed on military space by the European Union. It charts the history of the agency in general and its role in space in particular, delineating the many synergetic relations it has with other space-related institutions at EU level. It argues that EDA is as much a response to socioeconomic as strategic considerations, and that it acts to protect European competitiveness in the arms field, thereby highlighting the rising significance of EU military space policy for European security and military institutions.  相似文献   
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