无线远程电源控制系统的研制

本文介绍了一种基于GSM（全球移动通信系统）网络SMS（短信业务）的无线远程电源控制系统的原理及设计实现。该系统由一个无线GSM模块（WAVECOM公司的Q2403模块）和一个单片机（AT89S52）为核心的监控单元组成,监控单元利用AT指令通过串口和GSM模块进行通信,借助GSM模块Q2403使用户能够通过短信便捷地对相关设备进行断电、上电和重启等控制。     

Hubble Space Telescope observations of the nucleus fragment 73P/Schwassmann-Wachmann 3-C

The investigation of fragmented comets provides information on the physical properties and internal structure of cometary nuclei, as well as insights into the mechanisms responsible for cometary breakups. The Jupiter-family Comet 73P/Schwassmann-Wachmann 3 (73P/SW3) fragmented non-tidally into at least four components, and probably more, in the autumn of 1995. Fragment C was detected with the Wide Field Planetary Camera 2 (WFPC2) of the Hubble Space Telescope (HST) on 26 November 2001 when it was 3.26 AU from the Sun and 2.34 AU from the Earth. The high spatial resolution of the HST allowed us to separate the signal of the fragment from that of its coma, and to determine its R magnitude in the Johnson-Kron-Cousins photometric system from four images taken with the F675W filter. Assuming a spherical body with a geometric albedo of 0.04 and a linear phase coefficient of 0.04 mag deg⁻¹ for the R band, we derived an effective radius of . The pre-breakup radius of the original nucleus was estimated to be 1.1 km, which implies that the volume of fragment C is ∼25% of the total volume of the pre-breakup nucleus. The limited temporal coverage of our observations preclude deriving an accurate shape or rotational period; our measurements are consistent with a rather spherical body but an elongated shape cannot be excluded. Fragment C was very active despite its rather large heliocentric distance, with an estimated dust production rate of (∼130 metric tons day⁻¹). A very large fraction of the surface area of fragment C must have been sublimating to sustain such a high level of activity. Fragment C may be recovered at its next return in 2006, if it does not experience further fragmentation.     

Un exemple de volcanisme calco-alcalin de type orogénique mis en place en contexte de rifting (Cambrien de l'oued Rhebar,Meseta occidentale,Maroc)

The Middle Cambrian calc-alkaline Oued Rhebar volcanic complex (western Meseta, Morocco) compares with rocks originated in orogenic contexts. The La/Nb ratios are relatively high (5.2), suggesting a lithospheric mantle origin. The La/Ta ratios, higher than 26, and the negative Nb anomaly indicate a lithospheric source contaminated by the continental crust. These rocks were generated in the Mesetian Mid-Cambrian rift and would have inherited their orogenic signature from the partial melting of a previously metasomatized mantle. To cite this article: H. El Hadi et al., C. R. Geoscience 338 (2006).     

On the rotation of a moonlet embedded in planetary rings

We examine the rotation of a small moonlet embedded in planetary rings caused by impacts of ring particles, using analytic calculation and numerical orbital integration for the three-body problem. Taking into account the Rayleigh distribution of particles' orbital eccentricities and inclinations, we evaluate both systematic and random components of rotation, where the former arises from an average of a large number of small impacts and the latter is contribution from large impacts. Calculations for parameter values corresponding to inner parts of Saturn's rings show that a moonlet would spin slowly in the prograde direction if most impactors are small particles whose velocity dispersion is comparable to or smaller than the moonlet's escape velocity. However, we also find that the effect of the random component can be significant, if the velocity dispersion of particles is larger and/or impacts of large particles comparable to the moonlet's size are common: in this case, both prograde and retrograde rotations can be expected. In the case of a small moonlet embedded in planetary rings of equal-sized particles, we find that the systematic component dominates the moonlet rotation when m/M?0.1 (m and M are the mass of a particle and a moonlet, respectively), while the random component is dominant when m/M?0.3. We derive the condition for the random component to dominate moonlet rotation on the basis of our results of three-body orbital integration, and confirm agreement with N-body simulation.     

The evolution of the water distribution in a viscous protoplanetary disk

Astronomical observations have shown that protoplanetary disks are dynamic objects through which mass is transported and accreted by the central star. This transport causes the disks to decrease in mass and cool over time, and such evolution is expected to have occurred in our own solar nebula. Age dating of meteorite constituents shows that their creation, evolution, and accumulation occupied several Myr, and over this time disk properties would evolve significantly. Moreover, on this timescale, solid particles decouple from the gas in the disk and their evolution follows a different path. It is in this context that we must understand how our own solar nebula evolved and what effects this evolution had on the primitive materials contained within it. Here we present a model which tracks how the distribution of water changes in an evolving disk as the water-bearing species experience condensation, accretion, transport, collisional destruction, and vaporization. Because solids are transported in a disk at different rates depending on their sizes, the motions will lead to water being concentrated in some regions of a disk and depleted in others. These enhancements and depletions are consistent with the conditions needed to explain some aspects of the chemistry of chondritic meteorites and formation of giant planets. The levels of concentration and depletion, as well as their locations, depend strongly on the combined effects of the gaseous disk evolution, the formation of rapidly migrating rubble, and the growth of immobile planetesimals. Understanding how these processes operate simultaneously is critical to developing our models for meteorite parent body formation in the Solar System and giant planet formation throughout the galaxy. We present examples of evolution under a range of plausible assumptions and demonstrate how the chemical evolution of the inner region of a protoplanetary disk is intimately connected to the physical processes which occur in the outer regions.     

冰雪地球的研究进展综述

在大约6~7亿年前的新元古代时期，地球是否曾经被冰雪完全覆盖而成为了一个“冰雪地球”？如果是，什么诱发了这种全球性的冰川期？又是什么导致了它的融化？新元古代时期的极端气候变化对其后的寒武纪生命大爆发有何影响？围绕这些问题，古地质、古生物和古气候学界在最近几年展开了广泛的研究和激烈争论。根据现有的研究结果，地球在新元古代时期确实经历了数次地球历史上最为严重的全球性冰川期，但地球是否被完全冰封还需要更充分的古地质和古生物方面的证据来证明；利用气候模式对各种可能的外部强迫的模拟试验表明“冰雪地球”是很难形成的，并且，如果地球进入完全被冰封的状态，它将是难以被融化的；关于新元古代时期剧烈的气候变化对寒武纪生命大爆发所起的作用存在2种观点，一种认为气候变化导致了原始生命的基因突变并诱发了寒武纪生命爆发，另一种认为这种影响主要是生态方面的。     

河南省淅川地区地球化学特征

研究区沿淅川断裂带分布着以银、锑、钒为主的带状异常，通过地质大调查，对本区进行了地球化学分区，并重点检查了以银、锑、钒为主的异常。在寒武系底部水沟口组的硅质岩和粘土岩中发现了银、锑、钒多金属矿化带，伴生有金、铂、钯等贵金属矿化和稀土矿化。区域上存在有众多的以Ag，Sb，V为主的综合异常和相似的地质环境，具有一定的找矿前景。     

基于遥感和GIS的中国土地潜力资源的研究

在对中国土地资源综合研究基础上,利用已有研究成果,借助ＧＩＳ工具,利用层次分析法,对中国土地地潜力资源进行了综合分析和评价,在评价基础上,对中国土地资源的耕地潜力、生产潜力、生产潜力总量、人口容量潜力及综合潜力的大小和空间展布特征进行分析。结论为：中国土地资源潜力很力,但时空分布不均,在开发利用中,应因地制宜,采取不同的开发、利用的战略方针,在保护好现有土地资源和合理科学利用的基础上,谨慎开发,以