单片机控制的电子显示屏

本文介绍了由８０３１单片机控制的ＬＥＤ发光二极管阵列构成的电子显示屏显示原理、显示屏数据锁存、驱动接口电路、键盘接口电路、字模存放电路及软件框图。     

Application of Grain Size Analysis to Study Sedimentary Environment of Sand Dune in the Vicinity of Tumen River

The dunes in estuary of Tumen River in China lie to the area between the Jiushaping and Fangchuan in the left bank of Tumen River (Fig.1). The dis-tance is about 15～20 km between the dunes and the coast. It ranges from China to D. P. R. Korea and Russia. The range of the height of dunes is about 15～20 m and the width is 100～200 m. By the re-connaissance, we protracted 9 section planes of the dunes and collected 40 sand samples of the dunes, and identified the sedimentary environment …     

EMERGY ANALYSIS OF GRAIN PRODUCTION SYSTEM IN JIANGSU AND SHAANXI PROVINCE

1INTRODUCTIONGrain production has always been top-priority issue con-cerned by government and people (MA etal., 2002). Af-ter China put household contract responsibility system in force, its domestic issue of grain was basically settled in the mid 1980s (MA and XU, 1999). However, in the days when idea of sustainable development is broadly accepted, efficiency and sustainability of grain produc-tion are now in question, which have prompted interest in reviewing grain production patterns…     

Rapid climatic changes recorded in loess successions

Detailed grain-size analyses, both in China and western Europe, indicate the occurrence of short climatic cycles during loess deposition of the last glacial. Cold episodes coincided with enhanced deposition of relatively coarse loess and alternated with relatively warmer episodes with decreased deposition of finer loess and soil formation. In Europe, these oscillations may coincide with alternations of permafrost development and degradation. The short-term climatic events in the loess sections are similar to the Dansgaard–Oeschger events in ice-core records.     

Formation Pressure Evaluation Method for Single Well

The paper deals with the methods of formation pressure evaluation for a single well by using the very common ac-cepted parameters, such as drilling exponent , and flowline temperature , etc. which is part of compiling the end well report.     

Electric Discharges in the Protoplanetary Nebula as a Source of Impulse Magnetic Fields to Promote Dust Aggregation

Lightning discharge generated in the protoplanetary nebula is viewed as a temporally isolated surge in the flow of electrically charged particles, similar to that of terrestrial lightning. If the current is intense enough, a powerful circular impulse magnetic field is generated around the instantaneous virtual electric conductor. Such magnetic field is capable of magnetizing dust grains containing ferromagnetic components present in its vicinity to their saturation levels. As a result, dust grains attract one another, forming the aggregates. This magnetically driven attraction suggests an important process possibly operational at an early stage of the planetary accretion. Based on both a classical model for electric conductor, and the theory of Lienard–Wiechert electromagnetic potentials, our calculations show that the magnetic impulse due to a discharge channel of a few cm in diameter transferring a charge of about 10⁴ electrons reaches as high as 10 T. At these magnetic fields, the ferromagnetic dust grains, and possibly the already-formed larger aggregates as well, are easily magnetized to the saturation levels, producing compact clusters exhibiting permanent magnetic moments.     

沉积物粒度分析在厦门市第四纪环境研究和地层划分对比中的应用

采用MS2000型激光粒度分析仪进行测试，利用计算机粒度分析软件对数据进行整理和计算，绘制出样品的频率曲线、概率累积曲线以及粒度众数位值曲线等图件并进行沉积环境分析。厦门地区第四纪环境演化经历了中更新世同安组(含泥中粗砂、含泥细中砂、砂为主)海积一冲积一更新统上部龙海组(含泥粗中砂、含泥细中砂、含泥粗砂、粗砂、细中砂、含细砾中粗砂、中细砂等)冲积一洪冲积一更新世上部东山组(砂、砂砾、含泥中粗砂、粗砂、泥质中细砂、细砂、中粗砂等)冲洪积及部分海积(粉砂、细粉砂、含碳质泥、粘土、淤泥质粘土、粉砂质粘土等)一全新世长乐组(粉砂，淤泥质粘土、粉砂质粘土、碳质粘土、含砂淤泥质粘土，粉砂质亚粘土、粉细砂亚粘土等)海湾沉积。在解释环境变化的同时，说明粒度变化曲线在一定程度上可以作为地层划分的依据之一，并以此对研究区地层进行了详细划分。     

Carbonate aeolianites of western Saurashtra,India: experimental decipherment of the depositional mechanisms

Granular carbonate deposits of Late Pleistocene to Early Holocene age, commonly referred to as ‘miliolite limestone’, occur in a linear belt, parallel to the southern coast of Saurashtra, India. In the present study area these carbonate deposits are found in select valleys between ridges and mounds of pyroclastic material present in the Deccan trap plateau. Two different depositional histories have been proposed for these sediments. The presence of marine bioclasts led to the postulation of a marine origin for these deposits. The second school of thought propounded redeposition of the coastal sediments by aeolian processes. Although a few features could not be explained by the proposed aeolian model, critical comparison of these two views favoured the aeolian origin. The mode of occurrence, lithological and structural attributes, and microscopic evidence presented here, also support a possible aeolian origin for these deposits. Experimental observation indicates that these carbonate aeolianites represent backflow deposits, which accumulated because of the flow separation caused by the presence of topographic highs. The conspicuous concave‐up geometry of the deposit conformed to the shape of the separation bulb. In view of the inferred depositional mechanism, the disposition of the deposits and the signature of the palaeoflow direction suggest that the carbonate particles were derived from the north‐western coast of Saurashtra by strong south‐easterly winds. Massive granular carbonates with outsized basement clasts appear to be the product of avalanching of granular material from the higher contours because of oversteepening of the primary deposit.     

Advances in our understanding of the gem corundum deposits of the West Pacific continental margins intraplate basaltic fields

Recent discoveries over the last decade of new gemfields, exploitation of new and existing deposits, and application of relatively new techniques have greatly increased our knowledge of the basalt-derived gem sapphire–ruby–zircon deposits. In this paper we focus on the Late Mesozoic to Cenozoic intraplate basaltic fields of the West Pacific continental margins. We review advances made in understanding the genesis of these deposits, based on the application of newer techniques. We also critically review existing data on the gem corundum deposits, in order to further refine a model for their origin.In some of the intraplate basaltic fields, corundum-bearing xenoliths have been found showing a range of PT formation conditions from 790 °C at 0.85 GPa to as much as 1100 to 1200 °C at 1.0 to 2.5 GPa. Although most magmatic sapphires contain syngenetic inclusions of columbite-group phases, zircon, spinel and rutile, some contain additional nepheline and K-feldspar, suggesting crystallization from more undersaturated alkaline magma while the Weldborough field of NE Tasmania also contains molybdenite and beryl, suggesting at least some interaction with more fractionated ‘granitic-type’ magmas. There is a large range in PT conditions calculated for the metamorphic rubies (from 780 to 940 °C, through 800 to 1150 °C up to 1000 to 1300 °C). Fluid/melt inclusion studies on magmatic corundums generally suggest that they formed in a CO₂-rich environment from a ‘syenitic’ melt under a range of T conditions from 720 to 880 °C up to 1000 to 1200 °C. Oxygen isotope studies reveal that typical magmatic corundums have values of + 4.4 to 6.9‰, whereas metamorphic corundums from the same basaltic host have lower values of + 1.3 to 4.2‰.Geochronological studies have shown that some fields produced a simple eruptive and zircon/corundum crystallization event while others had multiple eruptive events but only one or two zircon crystallization events. For a few fields, some corundums/zircons crystallized in storage regions and then remained relatively inert for periods of 200 to 400 Ma without significant change before transport to the surface in the Cenozoic. Tectonic studies of the Australian region suggest that many of the corundums crystallized from magmas related to episodic basaltic volcanism in a tectonic regime of extension, associated with the opening of the Tasman and Coral Seas. For the Asian region, the magmatic–polygenetic corundums within the basaltic fields largely crystallized in a tectonic regime of distributed E–W extension, whereas the metamorphic-metasomatic corundums crystallised in a transpressional regime associated with the collision of the Indian Plate with the Eurasian Plate (e.g., [Garnier, V., Giuliani, G., Maluski, H., Ohnenstetter, D., Deloule, E., 2003. Ar–Ar and U–Pb ages of marble-hosted ruby deposits from Central and South-east Asia. Geophysical Research Abstracts 5, 03751; Garnier, V., Giuliani, G., Ohnenstetter, D., and Schwarz, D., 2004. Les gisements de corindon: classification et genese. Les placers a corindon gemme. Le Regne Mineral 55, 7-47; Garnier, V., Ohnenstetter, D., Giuliani, G., Maluski, H., Deloule, E., Phan Trong, T., Pham Van, L., Hoang Quang, V., 2005a. Age and significance of ruby-bearing marble from the Red River Shear Zone, Northern Vietnam. Canadian Mineralogist 43, 1315–1329]).     

Asymmetrically zoned reaction rims: assessment of grain boundary diffusivities and growth rates related to natural diffusion-controlled mineral reactions

This study explores garnet coronas around hedenbergite, which were formed by the reaction plagioclase + hedenbergite→garnet + quartz, to derive information about diffusion paths that allowed for material redistribution during reaction progress. Whereas quartz forms disconnected single grains along the garnet/hedenbergite boundaries, garnet forms ～20‐μm‐wide continuous polycrystalline rims along former plagioclase/hedenbergite phase boundaries. Individual garnet crystals are separated by low‐angle grain boundaries, which commonly form a direct link between the reaction interfaces of the plagioclase|garnet|hedenbergite succession. Compositional variations in garnet involve: (i) an overall asymmetric compositional zoning in Ca, Fe²⁺, Fe³⁺ and Al across the garnet layer; and (ii) micron‐scale compositional variations in the near‐grain boundary regions and along plagioclase/garnet phase boundaries. These compositional variations formed during garnet rim growth. Thereby, transfer of the chemical components occurred by a combination of fast‐path diffusion along grain boundaries within the garnet rim, slow diffusion through the interior of the garnet grains, and by fast diffusion along the garnet/plagioclase and the garnet/hedenbergite phase boundaries. Numerical simulation indicates that diffusion of Ca, Al and Fe²⁺ occurred about three to four, four and six to seven orders of magnitude faster along the grain boundaries than through the interior of the garnet grains. Fast‐path diffusion along grain boundaries contributed substantially to the bulk material transfer across the growing garnet rim. Despite the contribution of fast‐path diffusion, bulk diffusion through the garnet rim was too slow to allow for chemical equilibration of the phases involved in garnet rim formation even on a micrometre scale. Based on published garnet volume diffusion data the growth interval of a 20‐μm‐wide garnet rim is estimated at ～10³–10⁴ years at the inferred reaction conditions of 760 ± 50 °C at 7.6 kbar. Using the same parameterization of the growth law, 100‐μm‐ and 1‐mm‐thick garnet rims would grow within 10⁵–10⁶ and 10⁶–10⁷ years respectively.