基于LiDAR的农田地形环境三维重建方法

为克服传统农田土地平整测量方法耗时费力的特点，提出采用LiDAR技术对农田地形进行重建的探索性研究。通过HDL-32E型激光雷达等搭建了系统的硬件平台，应用C++语言编写了系统数据的采集程序；在此基础上对激光雷达所采集数据进行了标定，研究了农田地形重建系统中不同坐标系的转换方法；同时基于最小值去噪法设计了更适用于农田地形点云去噪的均值限差去噪法。通过对比在农田起伏较大区域不同坡度范围内RTK与激光雷达所测单元个数，对系统精度进行了评价；最后实现了车载农田地形重建系统的界面显示、应用与精度评估。结果表明，在10°~15°、25°~30°大坡度范围内激光雷达所获农田地形更为丰富，精度更高。该方法重建的农田地形模型点云数据和原始农田地形点云数据投影面积逼近度可达93%，验证了本文研究方法应用于农田地形环境重建的可行性，同时为今后的土地精细平整工作提供了理论参考与依据。     

Flare stars and solar bursts: High resolution in time and frequency

Coronal loops on the Sun and nearby stars are investigated using observations at 20 cm wavelength with high resolution in time and frequency. Observations of the dwarf M star AD Leonis with high time resolution using the Arecibo Observatory have resulted in the discovery of a quasi-periodic train of circularly polarized spikes with a mean periodicity of 32 ± 5 ms and a total duration of 150 ms. The individual spikes had rise times of 5 ms, leading to an upper limit to the linear size L 1.5 × 10⁸ cm for the spike emitter. This size is only 0.005 of the estimated radius of AD Leonis. Provided that the emitter is symmetric, it has a brightness temperature of T _B 10¹⁶ K, suggesting a coherent burst mechanism such as an electron-cyclotron maser. Coronal oscillations might modulate the maser output, producing the quasi-periodic spikes. Observations at closely spaced wavelengths, or high frequency resolution, using the Very Large Array have revealed narrow-band structure (v/v 0.01) in solar bursts and in the slowly-varying radiation of the dwarf M star YZ Canis Minoris. The narrow-band emission cannot be explained by continuum emission processes, but it might be attributed to electron-cyclotron maser radiation. Maser action at the second or first harmonic of the gyrofrequency implies magnetic field strengths of 250 and 500 G, respectively. Thus, observations with high resolution in time and frequency suggest coherent processes in the coronae of the Sun and dwarf M stars. The scientific potential of these discoveries may be best fulfilled by the construction of a solar-stellar synthesis radiotelescope.Proceedings of the Workshop on Radio Continua during Solar flares, held at Duino (Trieste), Italy, 27–31 May, 1985.     

Hydrometeorologische Ergebnisse aus Abflußmessungen im Bereich des Hintereisferners (Ötztaler Alpen) in den Jahren 1957 bis 1959

Zusammenfassung Während der Internationalen Geophysikalischen Jahre 1957 bis 1959 wurde an einer Pegelmeßstelle bei 2287 m Höhe der Abfluß vom Hintereis- und Kesselwandferner registriert. Im vorliegenden Arbeitsbericht sollen spezifischen Merkmale des Abflusses aus dem zu 58% vergleitscherten Einzugsgebiet 26,6 km²) im Zusammenhang mit den meteorologischen Beidingungen dargestellt werden.Der Jahresabfluß betrug im Haushaltsjahr 1957/58 1848 mm und im Haushaltsjahr 1958/59 1770 mm; bedingt durch den stark negative massenhaushat der Gletscher was die Gletscherspende mit 24% bzw. 20% des Jahresabflusses außergewöhnlich hoch. Der winterabfluß (Oktober bis März) betrug nur 5% bzw. 10% des Jahresabflusses; die drei Sommermonate Juli bis September Lieferten dagegen 76% bzw. 72%. Der größte Monatsabfluß wurde im August 1958 mit 575 mm, im Juli 1959 mit 559 mm registriert.Die Häufigkeitsverteilung der Tagesabflußmengen für das Jahr 1957/58 ließ eine Andauer des Niedrigwassers mit Tages-Mittelwerten kleiner als 18,8 l/s km² (0,5 m³/s) von 217 Tagen (Oktober bis Mai, 59% des Jahres) erkennen. Größere Tagesabflüsse als 225 l/s km² (6,0 m³/s) kamen nur im Juli und August vor. Als Maximum wurden Abflußwerte bis zu 640 l/s km² Gletscherfläche im Tagesmittel erreicht, entsprechen 55m Abflußhöhe von den Schnee- und Eisflächen. Der exponentielle Abfall der Abflußganglinie vom Herbst zum Minimum im Frühjahr deutet an, daß es sich bei Winterwasser vorwiegend um das verzögerte Abfließen von in den Gletschern zurückgehaltenem Schmelzwasser aus der vorangegangenen Ablationsperiode handelt. Das Ansteigen der Wasserführung nach dem Beiginn der Schneeschmelze im Frühjahr erfolgt wegen des Wiedergefrierens von Schmelzwasser und wegen des Retentionsvermögens der Schneedecke mit einiger Verzörgerung.Die unperiodischen Schwankungen im Abflußgang stehen in engem Zusammenhang mit Wettervorgängen, wobei Schneeniederschlägen die Größte Bedeutung zukommt, weil die hohe Albedo einer Neuschneedecke die Ablation auf den Gletschern tagelang fast völlig unterbrechen kann. Aus zweistündigen Mittelwerten wurde für die Monate Juni bis September der mittlere Tagesgang der Wasserführung ermittelt. Die Ursache für das frühere Eintreten des taglichen Abflußmaximums im Spätsommer durfte verminderte Abflußverzögerung sein. Die Beziehung zwischen den Abflußwerten der Pegel Steg-Hospiz und Vent läßt einen Jahresgang erkennen.

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Summary During the International Geophysical Years 1957–1959 the run-off from Hintereisferner and Kesselwandferner was recorded by a stream gauge installed at an altitude of 2287 m. a. s. 1. The annual run-off in relation to mass budget and precipitation has already been reported in [10, 11]. In the present report characteristic features of run-off from a catchment area (26.6 km²) glaciated to 58 per cent shall be discussed with regard to the meteorological conditions.In the budget years 1957/58 and 1958/59 the yearly run-off was 1848 mm and 1770 mm, respectively. Owing to the strongly negative mass budget of the glaciers the glacier quota of 24 per cent and of 20 per cent, respectively, of the annual run-off was exceptionally high. Winter run-off (October to March) amounting to 5 per cent and to 10 per cent, respectively, of the yearly run-off was only small while July to September supplied 76 per cent and 72 per cent, respectively. The maximum monthly run-off was recorded in August 1958 with 575 mm, and in July 1959 with 559 mm.The frequency distribution of the daily run-off in 1957/58 showed a period of low run-off during 217 days (October to May, 59 per cent of the year) with daily means below 18.8 l/s km² (0.5 m³/s). Daily run-off exceeding 225 l/s km² (6.0 m³/s) occurred only in July and August. Daily means exceeding 338 l/s km² (9.0 m³/s) were recorded only three times in July. The maximum daily means of run-off were up to 640 l/s km² of glacier surface which corresponds to 55 mm of run-off from the snow and ice surfaces. The highest two hourly mean value was 950 l/s km² of the glacier surface. The exponential decrease of the run-off curve from fall to the minimum in spring indicates that winter water consists mainly of the delayed run-off of melt water stored in the glaciers during the preceding ablation period. Owing to the refreezing of the melt water and to the storage capacity of the snow cover run-off is somewhat delayed after the snow melt has set in.The aperiodic variations in the run-off are closely related to weather conditions. Snow falls are of primary importance as the high albedo of a fresh snow cover may interrupt ablation on glaciers almost completely for days. The mean daily variation of run-off was determined from two-hourly mean values for the period June to September. The early occurrence of the daily run-off. The relation between the run-off values recorded at the water gauges Steg-Hospiz and Vent indicates and annual variation.

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Résumé Pendant les Années Géophysiques Internationales de 1957 à 1959 l'écoulement du Hintereisferner et du Kesselwandferner a été enregistré par un limnigraphe installé à une altitude 2287 m. Un rapport a déjà été présenté dans [10, 11] sur l'écoulement annuel en rapport avec le bilan hydrologique du bassin. Dans le présent rapoort il sera traité des caractères spécifiques de l'écoulement d'un bassin dont 58% sont recouverts par le glacier, les quels seront mis en rapport avec les conditions météorologiques.L'écoulement annuel au cours de l'année hydrologique 1957/58 a été de 1848 mm et dans l'année hydrologique 1958/59 de 1770 mm. L'eau libérée par la perte de substance glacière représente 24% pour 1957/58 et 20% pour 1958/59 de l'écoulement annuel. Les pourcentages extrêmement élevés doivent être attribués au bilan fortement négatif des glaciers. L'écoulement d'hiver (Octobre à Mars) représentant 5% pour l'année 1957/58 et 10% pour 1958/59 de l'écoulement annuel a été petit tandis que les trois mois d'été (Juillet–Septembre) fournissaient 76% (1957/58) et 72% (1958/59). L'écoulement mensuel le plus élevé a été enregistré en Aôut 1958 avec 575 mm, et, en Juillet 1959 avec 559 mm.La répartition des fréquences des écoulements journaliers pour l'année 1957/58 indique une période d'étiage de 217 jours (Octobre à Mai, 59% de l'année) avec valeurs journalières en dessous de 18.8 l/s km² (0.5 m³/s). Des écoulements dépassant 225 l/s km² (6.0 m³/s) n'ont été enregistrés qu'en Juillet et Aôut. Les moyennes journalières n'ont dépassé les 338 l/s km² (9.0 m³/s) que trois fois en Juillet. Les valeurs maximums des moyennes journalières d'écoulement se sont élevées à 640 l/s km² de la surface des glaciers, correspondant à 55 mm d'écoulement des surfaces de neige et de glace. La valeur maximum d'une moyenne de deux heures a été de 950 l/s km² de la surface des glaciers. La chute exponentielle de la courbe d'écoulement allant de l'automne au minimum enregistré au printemps indique que dans les cas d'étiage il s'agit de l'écoulement retardé des aux de fonte refenues dans les glaciers pendant la période d'ablation précédente. L'accroissement de l'écoulement après le comencement de la fonte de neige au printemps est retardé dans une certaine mesure par le regel des aux de fonte et la capacité de rétention de la couche de neige. Les variations apériodiques dans l'écoulement sont en relations étroites avec les conditions atmospheriques dont les chutes de neige sont de la plus grade importance car l'albédo élevé d'une couche de neige fraîche interrompt parfois et presque complétement l'ablation sur les glaciers pour des jours entiers.L'amplitude moyenne de la variation journalière de l'écoulement a été, pour les mois de Juin à Septembre, détérminée à la base des valeurs moyennes de deux heures. L'apparition précoce du maximum d'écoulement journalier en fin d'été est probablement due à la diminution du retardement de l'écoulement en cette période. La relation entre le valeurs d'écoulement des limnigraphes de Steg-Hospiz et de Vent met en évidence une variation annuelle.

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Die für diesen Bericht erforderliche weitere Bearbeitung der Abflußdaten und die Fertigstellung des Manuskriptes wurde dem Verfasser im Rahmen seiner Tätigkeit bei der Kommission für Glaziologie an der Bayerischen Akademie der Wissenschaften ermöglicht, wofür an dieser Stelle gedankt sei.     

叠前时间偏移方法在煤田勘探中的应用

根据克希霍夫积分法的原理,介绍了叠前时间偏移的方法特点,实现过程,以及对地震资料的要求,依托国家重大产业技术专项“西部煤炭资源高精度三维地震勘探”工程,对“青海省鱼卡煤田四井田高精度三维地震勘探”资料进行叠前时间偏移,结果表明其能较好地解决成像质量差、能量聚焦不明显、绕射波收敛不理想等方面的难题。通过与叠后时间偏移对比,对于大倾角地层、断块小且多的破碎带、陡倾角不对称向斜等地质问题,其叠前时间偏移剖面成像质量都有明显的提高,反映的构造关系更加清晰,同相轴连续性增强。总结该方法在多个矿区的推广经验．认为合理的观测系统、较高的资料信噪比,准确的测量资料及较高的中表层速度调查精度是做好叠前时间偏移的前提。     

Noise storms and the structure of microwave emission of solar active regions

Solar radio and microwave sources were observed with the Very Large Array (VLA) and the RATAN-600, providing high spatial resolution at 91 cm (VLA) and detailed spectral and polarization data at microwave wavelengths (1.7 to 20 cm - RATAN). The radio observations have been compared with images from the Soft X-ray Telescope (SXT) aboard theYohkoh satellite and with full-disk phoptospheric magnetic field data from the Kislovodsk Station of the Pulkovo Observatory. The VLA observations at 91 cm show fluctuating nonthermal noise storm sources in the middle corona. The active regions that were responsible for the noise storms generally had weaker microwave emission, fainter thermal soft X-ray emission, as well as less intense coronal magnetic fields than those associated with other active regions on the solar disk. The noise storms did, however, originate in active regions whose magnetic fields and radiation properties were evolving on timescales of days or less. We interpret these noise storms in terms of accelerated particles trapped in radiation belts above or near active regions, forming a decimetric coronal halo. The particles trapped in the radiation belts may be the source of other forms of nonthermal radio emission, while also providing a reservoir from which energetic particles may drain down into lower-lying magnetic structures.Presented at the CESRA-Workshop on Coronal Magnetic Energy Release at Caputh near Potsdam in May 1994.     

La Formation glaciaire de la Mambéré (République Centrafricaine): Reconstitution paléogéographique et implications à l'échelle du Paléozoique africain

The Mambéré Formation constitutes a horizontal unit located in the western and southwestern part of the Central African Republic. Stratigraphical and sedimentological study provides strong argument to attribute these deposits a glacial origin. A palaeogeographical reconstruction has been outlined in order to precise the age of the formation. Two main categories of glacial deposits have been recognized:

glaciogenic deposits made of basal tills (with facetted pebbles) and flow tills (with flattened blunt pebbles);

reworked glacial deposits formed of sandstones and conglomeratic sandstones, in continuous beds, lenses or isolated blocks, together with siltstones and bedded sandstones.

The southerly provenance of the detrital material is demonstrated by quartz grain surface analysis and heavy-mineral study. This material results essentially from the dismantling of the Precambrian Schistoquartzitic Complex and secondarily from the Granitogneissic Complex. According to the palaeomagnetic polar paths and the migration of the glacial centers over the African continent during the Palaeozoic, the Mambéré Formation may be attributed a Lower Silurian age by reference to similar formations observed in Cameroon or a Lower Carboniferous age by comparison with the glacial formations reported from Niger and Egypt.     

Restructuring of polygalacturonate on alumina upon hydration—Effect on phosphate sorption kinetics

Hydration of organic coatings in soils is expected to affect the sorption of oxyanions onto hydrous Fe and Al oxides. We hypothesized that the hydration of polygalacturonate (PGA) coatings on alumina (Al₂O₃) increases their permeability for phosphate. Pure and PGA-coated alumina were equilibrated in deionized water for 2 and 170 h at pH 5 and 20 °C before studying (i) their porosity with N₂ gas adsorption and ¹H NMR relaxometry, (ii) structural changes of PGA-coatings with differential scanning calorimetry (DSC), and (iii) the kinetics of phosphate sorption and PGA desorption in batch experiments. Scanning electron micrographs revealed that PGA molecules formed three-dimensional networks with pores ranging in size from <10 to several hundred nanometers. Our NMR results showed that the water content of intraparticle alumina pores decreased upon PGA sorption, indicating a displacement of pore water by PGA. The amount of water in interparticle alumina pores increased strongly after PGA addition, however, and was attributed to water in pores of PGA and/or in pores at the PGA-alumina interface. The flexibility of PGA molecules and the fraction of a PGA gel phase increased within one week of hydration, implying restructuring of PGA. Hydration of PGA coatings increased the amount of phosphate defined as instantaneously sorbed by 84%, showing that restructuring of PGA enhanced the accessibility of phosphate to external alumina surfaces. Despite the fact that the efficacy of phosphate to displace PGA was higher after 170 h than after 2 h, a higher phosphate surface loading was required after 170 h to set off PGA desorption. Our findings imply that the number of PGA chain segments directly attached to the alumina surface decreased with time. We conclude that hydration/dehydration of polymeric surface coatings affects the sorption kinetics of oxyanions, and may thus control the sorption and transport of solutes in soils.     

鄂尔多斯盆地中部奥陶系方解石脉中包裹体流体势研究

结合前人研究成果，归纳出了一种利用盐水包裹体均一温度与盐度确定流体势的方法，并对鄂尔多斯盆地中部气田奥陶系方解石脉中包裹体进行了流体势计算，推算出了古流体运移方向。     

Paléoenvironnements et caractérisation des roches mères pétrolières des séries pré-salifères du bassin intérieur du Gabon

The Interior Basin of Gabon, created during the break-up between South America and Africa, displays thick Neoproterozoic to Aptian p.p. fluvio-lacustrine deposits overlain by Aptian to Albian marine facies. Rock–Eval analyses from outcrop and drillhole samples show high content in organic matter (up to 25%) related to types I and II. These intervals are encountered within Permian, Neocomian–Barremian as well as Aptian siliciclastic succession. They constitute fairly good to excellent potential petroleum source rocks, which are most probably at the origin of oil indices recognized both in drillholes and in surface.     

无水氯化镍及芳烃基二膦酸四乙酯的制备

1，4—二溴苯，4，4’—二溴联苯、4，4’—二溴三联和亚磷酸三乙酯在催化剂无氯化镍催化下，干燥氮气保护．反应得到相应的有机二磷酸四乙酯。