LEGRI instrument health. A historical review     

Julia Suso  Pere Blay  Almudena Robert  Victor Reglero  Chris J. Eyles 《Astrophysics and Space Science》2001,276(1):299-309

LEGRI has been operating successfully on MINISAT-01 since its switch-on the 22nd of May 1997. HouseKeeping (HK) data have been continuously receivedfor nearly two years by LEGRI SOC in Valencia, and subsequently checked on adaily basis and then stored for long term monitoring analysis.LEGRI HouseKeeping data include three critical operating parameters:temperature, power and polarisation voltages. Six temperature sensors arespread over the different LEGRI units: Detector Unit, Data Processing Unit,High Voltage Unit and Star Sensor. Voltages are measured at eight differentpoints. Detector Unit temperature and polarisation voltage are thecritical parameters for LEGRI operation. Solid state detectors aresensitive to changes not only in polarisation but also in temperature.Around one and a half million of measurements for each of the HK fourteen parameters have been recorded and analysed. The data show a very remarkablestability, within the expected margins, and the averages are very close to theoptimal design values. Special attention has been paid to the detectorpolarisation voltages analysis with a mean value of 286 ± 2 V when the detectors are operating. Thermal control over all the LEGRI units shows a remarkable stability in their temperatures.On the detector plane a mean value of T _det = 13 ± 2 ^°C has been found.We can therefore conclude that LEGRI as a system has been operating withinits optimal design conditions. We also want to point out the excellentperformance of the MINISAT-01 thermal control system.  相似文献   

Activity-composition relations in the system CaCO₃-MgCO₃ predicted from static structure energy calculations and Monte Carlo simulations     

Victor L. Vinograd  Benjamin P. Burton  Neil L. Allan 《Geochimica et cosmochimica acta》2007,71(4):974-983

Thermodynamic mixing properties and subsolidus phase relations of the rhombohedral carbonate system, (1 − x) · CaCO₃ − x · MgCO₃, were modelled in the temperature range of 623-2023 K with static structure energy calculations based on well-parameterised empirical interatomic potentials. Relaxed static structure energies of a large set of randomly varied structures in a 4 × 4 × 1 supercell of calcite (a = 19.952 Å, c = 17.061 Å) were calculated with the General Utility Lattice Program (GULP). These energies were cluster expanded in a basis set of 12 pair-wise effective interactions. Temperature-dependent enthalpies of mixing were calculated by the Monte Carlo method. Free energies of mixing were obtained by thermodynamic integration of the Monte Carlo results. The calculated phase diagram is in good agreement with experimental phase boundaries.  相似文献   

Temporal and spatial variability of cross-fault groundwater-level differences: the impact of fault-induced permeability reduction,precipitation and evapotranspiration     

Lapperre  Rimbaud E.  Bense  Victor F.  Kasse  Cornelis  van Balen  Ronald T. 《Hydrogeology Journal》2022,30(4):1233-1257

Hydrogeology Journal - Faults in the Roer Valley Rift System (Netherlands, Belgium, and Germany) act as barriers to lateral groundwater flow in unconsolidated sedimentary aquifers. This causes a...  相似文献   

Projected changes in meteorological drought over East Africa inferred from bias-adjusted CMIP6 models     

Ayugi  Brian  Shilenje  Zablon Weku  Babaousmail  Hassen  Lim Kam Sian  Kenny T. C.  Mumo  Richard  Dike  Victor Nnamdi  Iyakaremye  Vedaste  Chehbouni  Abdelghani  Ongoma  Victor 《Natural Hazards》2022,113(2):1151-1176

Natural Hazards - The ongoing global warming has caused unprecedented changes in the climate system, leading to an increase in the intensity and frequency of weather and climate extremes. This...  相似文献   

Construction of Structural Geological Model Using Monte Carlo Simulation     

Xavier  Bruna Catarino  Egydio-Silva  Marcos  Sadowski  Georg Robert  de Assis Silva  Bruno  Takara  Victor Junji 《Geotechnical and Geological Engineering》2022,40(3):1345-1361

Geotechnical and Geological Engineering - To optimize the prediction of structural geological conditions in the underground as of data collected at the surface, due to the usual great uncertainties...  相似文献   

Revisiting forest impact on atmospheric water vapor transport and precipitation   总被引：1，自引：0，他引：1  

Anastassia M. Makarieva  Victor G. Gorshkov  Bai-Lian Li 《Theoretical and Applied Climatology》2013,111(1-2):79-96

Using a robust global precipitation database, we analyze coast-to-interior seasonal precipitation distributions over the world’s major forest regions. We find that the active functioning of boreal forests in summer is associated with an intense ocean-to-land moisture transport, which declines in winter when forest functioning is minimal. This seasonal switch manifests itself as a change in the exponential scale length of precipitation distribution, which exceeds 15?×?10³ km in summer but decreases to (3–4)?×?10³ km in winter. In equatorial rainforests, which are photosynthetically active throughout the year, annual precipitation remains approximately constant, while the coefficient of variation of monthly precipitation significantly declines toward the continent interior. Precipitation over forest during the periods of active forest functioning is always higher than over the adjacent ocean. Such precipitation patterns support the biotic pump concept according to which forest cover drives the ocean-to-land atmospheric moisture transport on a continental scale.  相似文献   

The UNFCCC as a negotiation forum: towards common but more differentiated responsibilities     

Jutta Brunnée  Charlotte Streck 《Climate Policy》2013,13(5):589-607

The principle of common but differentiated responsibilities and respective capabilities (CBDRC) captures the idea that it is the common responsibility of states to protect and restore the environment but that the levels and forms of states’ individual responsibilities may be differentiated according to their own national circumstances. This principle has shaped the evolution of the climate regime and has played an important role in promoting compromise and agreement. It is argued that some twenty years after the adoption of the United Nations Framework Convention on Climate Change (UNFCCC), the principle of CBDRC remains as relevant as ever. The practice of Parties under the regime and, most recently, the concerted efforts to shape and flesh out the meaning of the principle, underscore the central role that it plays. At the same time, the binary understanding of CBDRC in the Kyoto Protocol is being replaced with a more nuanced, multifaceted understanding. The evolving interpretation of CBDRC is considered, and its continued relevance as the nucleus of a global burden-sharing regime for addressing climate change is demonstrated.

Policy relevance

The development of a common understanding of the principle of CBDRC is essential for the burden sharing and responsibilities under a future climate agreement. The CBDRC principle captures the idea that it is the common responsibility of states to protect and restore the environment, but that the levels and forms of states’ individual responsibilities may be differentiated according to their own national circumstances. This article informs the international climate change negotiations by considering the development of the principle of CBDRC under the UNFCCC over time. It is concluded that, although there has been a significant shift in how the principle is understood, it remains crucial to the integrity and stability of the climate regime.  相似文献   

Morphological evolution of discs in clusters     

Chiara Mastropietro  Ben Moore  Lucio Mayer  Victor P. Debattista  Rocco Piffaretti  Joachim Stadel 《Monthly notices of the Royal Astronomical Society》2005,364(2):607-619

  相似文献   

Multiwavelength focusing with the Sun as gravitational lens     

Laurent Koechlin  Denis Serre  Gerald K. Skinner  Peter Von Ballmoos  Thomas Crouzil 《Experimental Astronomy》2005,20(1-3):307-315

The light deviation caused by the gravitational potential in the vicinity of the sun could be used as a means of focussing radiation that cannot be focussed easily otherwise. The gravitational lens formed by the sun is not stigmatic, but does have the advantage of being achromatic and acts identically on all types of mass-less radiations. For a source at infinity, its geometrical characteristics present a “caustic” line starting at 550 astronomical units (UA) downstream from the sun. In a plane perpendicular to that caustic line, images of distant objects are formed.The perturbations by the solar corona plasma will significantly blur electromagnetic radiation for wavelengths longer than those of the IR domain. At shorter wavelengths, for example the γ domain, the focussing process could lead to 10⁸ amplification factors. In order to reach the regions where images are formed, long distance space missions are necessary. Once launched, missions of this type would be dedicated to a single field. Some possible targets are considered, such as Sagitarius A observed in X and γ rays.In this paper we study the point spread function (PSF) of the sun as a gravitational lens. Taking into account perturbations by the planets, the non sphericity of the sun and coronal plasma index, we derive limits within which such observations could be possible.  相似文献   

The development of the Poincaré-similar elements with eccentric anomaly as the independent variable     

Victor R. Bond 《Celestial Mechanics and Dynamical Astronomy》1976,14(3):333-311

A new set of element differential equations for the perturbed two-body motion is derived. The elements are canonical and are similar to the classical canonical Poincaré elements, which have time as the independent variable. The phase space is extended by introducing the total energy and time as canonically conjugated variables. The new independent variable is, to within an additive constant, the eccentric anomaly. These elements are compared to the Kustaanheimo-Stiefel (KS) element differential equations, which also have the eccentric anomaly as the independent variable. For several numerical examples, the accuracy and stability of the new set are equal to those of the KS solution. This comparable accuracy result can probably be attributed to the fact that both sets have the same time element and very similar energy elements. The new set has only 8 elements, compared to 10 elements for the KS set. Both sets are free from singularities due to vanishing eccentricity and inclination.  相似文献