Nonlinear plasma wave processes observed in the polar cusp

We present observations of electric and magnetic field variations from proton (about few Hz) to electron cyclotron frequencies (about few kHz) obtained by STAFF instrument on Cluster satellites during two cusp crossings, at ∼6 R _E altitude, in September 2002. The cusp was identified by the presence of intensive fluxes of counter streaming electrons with low energies and broadband wave activity which is typical for this region. Special attention is given for the interval of measurements when the waveform of the magnetic field fluctuations was taken in this region by CLUSTER satellites. The wave has been processed using the wavelet and bispectral analysis. Results showing the cascade of turbulence and wave-wave interactions are presented in this paper. A three wave process can be responsible for the broadening of the wave spectra in the polar cusp.     

The GPS Toolbox ITRF Transformations

The GPS Toolbox is dedicated to highlighting algorithms and source code utilized by GPS engineers and scientists. If you have an interesting subroutine or program you would like to share with our readers, please pass it along so that we might continue to bring you this column; e-mail it to us at gps-toolbox@ngs.noaa.gov. To comment on any of the source code discussed here, or to leave a request for a piece of source code you may be looking for, visit our web site at http:/www.ngs.noaa.gov/gps-toolbox. This column is edited by Stephen Hilla, National Geodetic Survey, NOAA, Silver Spring, Maryland, and Mike Craymer, Geodetic Survey Division, Natural Resources Canada, Ottawa, Ontario, Canada. ? 2002 Wiley Periodicals, Inc.     

全站仪近距离测距精度检验方法的探讨

提出了室内基线法，给出了相应的数据处理方法，并用实测数据进行了计算，结果显示全站仪在室内、短边条件下的测距精度较标称精度有很大的提高。该法所得结果与现存两种方法的结果基本相当，从而证明了该法能够客观地反映出工业测量用全站仪的近距离测距精度。     

中尺度数值模式(MM5V3)在沈阳区域气象中心的试用

简单介绍了沈阳区域气象中心在微机上调试和试用中尺度数值模式MM5V3的情况，MM5V3在前、后处理上使用Fortran90编程，与MM5V2有一定差别，利用T106L19资料和常规探空报形成经、纬网格的初值，预处理场和侧边界，代入模式前处理系统中，模式运行完毕后，预报产品直接进入MICAPS、Vis5d、Grads系统，进行图形显示，在2000年汛期试用中发现，MM5V3对东北地区的强降水过程有一定的预报能力，预报评分表明，MM5V3的降水预报结果和MM5V2互有优劣，总体来看，MM5V3的预报质量略高于MM5V2。     

Progress in Carrier Phase Time Transfer

The progress of the joint Pilot Project for time transfer, formed by the International GPS Service (IGS) and the Bureal International des Poids et Mesures (BIPM), was recently reviewed. Three notable milestones were set. (1) The IGS will implement, at least in a test mode, an internally realized time scale based on an integration of combined frequency standards within the IGS network. This will eventually become the reference time scale for all IGS clock products (instead of the current GPS broadcast time). (2) A new procedure for combined receiver and satellite clock products will be implemented officially in November 2000. Receiver clocks are an entirely new product of the IGS. (3) The BIPM will coordinate an effort to calibrate all Ashtech Z12-T (and possibly other) receivers suitable for time transfer applications, either differentially or absolutely. Progress reports will be presented publicly in the spring 2001. ? 2001 John Wiley & Sons, Inc.     

废物资源化利用的理论与方法——基于沱牌集团的应用分析

文章通过对废物资源化利用的历史回忆，从能量一经济－环境的复合系统，论述了能量的投入推动着经济的发展，经济发展又会带来环境的破坏，要在经济发展的同时减少环境的污染程度，不能采取简单的末端治理方式，而应从能量投入的源头开始治理，为此，要采取清洁的生产方式，减少废物排放量，并把真正的废物进行资源化利用，确保系统的完备性，做到能量投入减量化，经济发展,高速化，环境污染低量化，由此，结合沱牌集团的计划项目，我们模拟了沱牌集团废物资源化利用的框架，并用具体实例进行分析。     

Determination of Geopotential Differences between Local Vertical Datums and Realization of a World Height System

The methodology developed for connecting Local Vertical Datums (LVD) was applied to the Australian Height Datum (AHD) and the North American Vertical Datum (NAVD88). The geopotential values at AHD and NAVD88 were computed and the corresponding vertical offset of 974 mm with rms 51 mm was obtained between the zero reference surfaces defined by AHD and NAVD88. The solution is based on the four primary geodetic parameters, the GPS/levelling sites and the geopotential model EGM96. The Global Height System (or the Major Vertical Datum) can be defined by a geoidal geopotential value used in the solution as the reference value, or by the geopotential value of the LVD, e.g. NAVD88.     

秦岭八卦庙金矿金的矿化与铂族金属的富集

文章报道了八卦庙特大型金矿床中伴生的铂族金属矿化的地质特征，岩石矿物学特征和新发现矿物－－自然（钨）钌矿的基本矿物学特征，铂族金属矿化与金矿化围岩蚀变的关系研究表明，八卦庙金矿中伴生的铂族金属富集于后期岩浆热液改造期，成矿物质主要来源于后期改造的热液，铂族金属的富集与金的富集呈明显的正消长关系，成矿的温度为140－500度，矿化深度＞3．7km，成矿流体是以中酸性岩浆热液为主的多成因热国水，矿物组成以复杂的高温硫化物，合金类为主要特征；化学成分也比较复杂，以Au,Cu,As,Ag,Ni,Co,Sb,S和铂族金属Ru,Ir,Os异常等为特点，这类伴生铂族金属的金矿床将为秦岭成矿带寻找铂族金属提供了典型实例。     

Generation of Deccan Trap magmas

Deccan Trap magmas may have erupted through multiple centers, the most prominent of which may have been a shield volcano-like structure in the Western Ghats area. The lavas are predominantly tholeiitic; alkalic mafic lavas and carbonatites are rare. Radioisotope dating, magnetic chronology, and age constraints from paleontology indicate that although the eruption started some 68 Ma, the bulk of lavas erupted at around 65–66 Ma. Paleomagnetic constraints indicate an uncertainty of ± 500,000 years for peak volcanic activity at 65 m.y. in the type section of the Western Ghats. Maximum magma residence times were calculated in this study based on growth rates of “giant plagioclase” crystals in lavas that marked the end phase of volcanic activity of different magma chambers. These calculations suggest that the > 1.7 km thick Western Ghats section might have erupted within a much shorter time interval of ∼ 55,000 years, implying phenomenal eruption rates that are orders of magnitude larger than any present-day eruption rate from any tectonic environment. Other significant observations/conclusions are as follows: (1) Deccan lavas can be grouped into stratigraphic subdivisions based on their geochemistry; (2) While some formations are relatively uncontaminated others are strongly contaminated by the continental crust; (3) Deccan magmas were produced by 15–30% melting of a Fe-rich lherzolitic source at ∼ 3–2 GPa; (4) Parent magmas of the relatively uncontaminated Ambenali formation had a primitive composition with 16%MgO, 47%SiO₂; (5) Deccan magmas were generated much deeper and by significantly more melting than other continental flood basalt provinces; (6) The erupted Deccan tholeiitic lavas underwent fractionation and magma mixing at ∼ 0.2 GPa. The composition and origin of the crust and crust/mantle boundary beneath the Deccan are discussed with respect to the influence of Deccan magmatic episode.     

High-speed photography of the bubble generated by an airgun1

High-speed photography has been used visually to study the shape, surface, turbulence and behaviour of an underwater oscillating bubble generated by an airgun. The source was a BOLT airgun with a chamber volume of 1.6cu.in., placed in a 0.85m³ tank at 0.5m depth. Near-field signatures were also recorded in order to compare the instant photographs of the oscillating bubble with the pressure field recorded about 25 cm from the gun. Estimations of the bubble-wall velocity and bubble radius estimated from high-speed film sequences are also presented, and are compared with modelled results. The deviation between the modelled and measured bubble radii was at most 9%. In order to check the capacity for transmission of light through the bubble, a concentrated laser beam was used as illumination. We found that the air bubble is a strong scattering medium of laser light, hence the bubble is opaque.