芝麻坊石榴子石二辉橄榄岩多期变质演化及其地幔过程

Many garnet peridotite bodies are enclosed in ultrahigh-pressure (UHP) gneisses and/or migmatites in worldwide UHP terranes formed by subduction of continental crust. On the basis of petrochemical data, a group of garnet peridotites have been derived from depleted mantle and were subsequently metasomatized by melts and/or fluids derived from the subducted continental crust. However, their depletion and enrichment processes and tectonic evolutions are still in conflicts. New evidences for metamorphism of garnet lherzolite from Zhimafang, Donghai County, Sulu UHP terrane are reported. The garnet lherzolite have experienced a prolonged multistage metamorphic history. At least seven stages of recrystallization have been identified based on detailed analysis of reaction textures and mineral compositions. Stage I was a high-pressure and high-temperature enriched garnet lherzolite stage, which is inferred from the presence of high Ca-Cr core of garnet porphyroclast and inclusions of high-Mg clinopyroxene, high-Al-Cr orthopyroxene and high-Mg olivine. Stage II is a high-temperature and low-pressure depleted spinel-hurzbergite or spinel-dunite stage, as indicated by the presence of relict Al-rich spinel, very high-Mg and low-Ni olivine and high-Mg orthopyroxene included in the low-Cr mantle of the porphyroclastic garnet and core of fine-grained neoblastic garnet, clinopyroxene is absent in this stage. Stage III is an hydrous amphibole spinel-lherzolite stage, which recorded events of cooling and metasomatic re-enrichment, this stage is manifested by metasomatic origin of amphibole and phlogopite-bearing porphyroblastic clinopyroxene, and porphyroblastic orthopyroxene. Stage IV is a high-pressure amphibole garnet-lherzolite stage, which is indicated by the formation of low-Cr mantle of the porphyroclastic garnet and amphibole-bearing low-Cr core of neoblastic garnet. Stage V is an UHP metamorphic garnet-lherzolite stage, which is characterized by the formation of high-Cr rim of both porphyroclastic and neoblastic garnet and recrystallization of olivine, clinopyroxene and orthopyroxene in the matrix. During UHP metamorphism, the garnet lherzolite is dehydrated, hornblende decomposed to clinopyroxene and olivine. Stage VI is a high-pressure decompression amphibole garnet-lherzolite stage, indicated by formation of later coarse-grained pargasitic hornblende and phlogopite in the garnet stability field. Stage VII is a low-pressure decompression amphibole-chlorite spinel-lherzolite stage, indicated by replacement of garnet by kelyphite of high-Al orthopyroxene + aluminous spinel + tremolitic amphibole + chlorite + talc. The metamorphic evolutions of Zhimafang garnet lherzolite suggest that it displays progressive mantle wedge convection during the subduction of previous oceanic and subsequent continental slab. We propose that the Zhimafang garnet lherzolite were originated from enriched deep mantle wedge above the previously subducted oceanic slab, subduction of oceanic slab resulted in their convection to shallower back arc and sub-arc setting, decompressional melting transformed the enriched garnet-lherzolite to depleted spinel-hurzbergite or spinel-dunite, the spinel-hurzbergite or spinel dunite was then convected to the hydrous mantle wedge corner driven by corner flow and was cooled and metasomatized by slab-derived melts/fluids, and was transformed to enriched lherzolite. The lherzolites formed a downward mantle wedge layer above successively subducted continental crust. The peridotite subducted together with the underlying continental crust and suffered UHP metamorphism. Finally, the garnet-lherzolite exhumed to the earth surface together with the UHP terrane. Detailed analyses of reaction textures and mineral compositions revealed several stages of metasomatism related to continental subduction and exhumation.

GIS接受外部空间数据的初步探讨——兼论ARC/INFO~的数据接受方式

数据是地理信息系统 (GIS)应用的核心。现实世界的数据具有普遍的多样性 ,关于 GIS接受不同数据的研究已成为当前 GIS研究中的一个难点和热点。从常见空间数据类型的格式、GIS接受外部空间数据的方式以及 GIS接受外部空间数据中的数据精度、比例尺、坐标变换等几个方面 ,对外部空间数据处理系统的数据向 GIS转换的问题进行了探讨 ,同时以通用 GIS工具软件 ARC/INFO为例分析了其接受外部矢量空间数据的方式。

ARC/INFOR~接受Surfer图文数据的实现

数据是地理信息系统 (GIS)应用的核心。现实世界的数据具有普遍的多样性 ,关于 GIS接受不同数据的研究已成为当前 GIS研究中的一个难点和热点。本文根据通用 GIS工具软件 ARC/INFO接受外部空间数据的方式和图形分析软件 Surfer的数据格式特征 ,运用特定的处理方法实现了由 Surfer格式数据向 ARC/ INFO矢量格式数据 (Coverage)的转换 ,使 ARC/ INFO接受外部数据格式的范围拓宽 ,数据处理能力增强。

Tectonic geomorphology of the Ryukyu Trench-Arc-Backarc System: geological-geophysical exploration and mapping

OKINAWA TROUGH; BASIN

Arc Voltage Fluctuation in DC Laminar and Turbulent Plasma Jets Generat Ion

Arc voltage fluctuations in a direct current (DC) non-transferred arc plasma generator are experimentally studied, in generating a jet in the laminar, transitional and turbulent regimes. The study is with a view toward elucidating the mechanism of the fluctuations and their relationship with the generating parameters, arc root movement and flow regimes. Results indicate that the existence of a 300 Hz alternating current (AC) component in the power supply ripples does not cause the transition of the laminar plasma jet into a turbulent state. There exists a high frequency fluctuation at 4 kHz in the turbulent jet regime. It may be related to the rapid movement of the anode attachment point of the arc.

Characteristics and Sub-Characteristics of Two-Dimensional Parabolized Stability Equations

特征分析表明：对原始扰动量的抛物化稳定性方程组(PSE),它在亚超音速区分别具有椭圆和抛物特性,给出PSE特征对马赫数的依赖关系,阐明PSE仅把信息对流-扩散传播特性抛物化,而保留了信息对流-扰动传播特性,因此PSE应称为扩散抛物化稳定性方程(DPSE)。

Arc Root Attachment on the Anode Surface of Arc Plasma Torch Observed with a Novel Method

The arc-root attachment on the anode surface of a dc non-transferred arc plasma torch has been successfully observed using a novel approach. A specially designed copper mirror with a boron nitride film coated on its surface central-region is employed to avoid the effect of intensive light emitted from the arc column upon the observation of weakly luminous arc root. It is found that the arc-root attachment is diffusive on the anode surface of the argon plasma torch, while constricted arc roots often occur when hydrogen or nitrogen is added into argon as the plasma-forming gas.

Characteristics of Gliding Arc Discharge Plasma

A gliding arc discharge plasma and its characteristics are described. Analysis on the production principle of the plasma is presented. Some experimental results about two novel types of the gliding arc plasma generator were obtained. These types of gliding arc plasma are potentially used in chemical industry and environment engineering.

Study of Gliding Arc Discharge Plasma

本文研究了滑动弧放电过程中电参数的变化，并对滑动弧等离子体中的非平衡度和各参数之间关系进行了讨论。应用了双通道电弧模型 ，对电弧在气流作用下的运动规律进行了数值模拟。模拟的结果有助于分析滑动弧非平衡等离子体的产生机理。 The elelctric parameters change during discharge is studied and the relationship between non-equilibrium degree and parameters is discussed for gliding arc discharge.Using two-channel model, the rules of arc moving due to effect of the airflow is simulated.The numerical simulation results can help analyzing the generation mechanism of gliding arc non-equilibrium plasma.

Carbon transition efficiency and process cost in high-rate, large-area deposition of diamond films by DC arc plasma jet

A new DC plasma torch in which are jet states and deposition parameters can be regulated over a wide range has been built. It showed advantages in producing stable plasma conditions at a small gas flow rate. Plasma jets with and without magnetically rotated arcs could be generated. With straight are jet deposition, diamond films could be formed at a rate of 39 mu m/h on Mo substrates of Phi 25 mm, and the conversion rate of carbon in CH4 to diamond was less than 3%. Under magnetically rotated conditions, diamond films could be deposited uniformly in a range of Phi 40 mm at 30 mu m/h, with a quite low total gas flow rate and high carbon conversion rate of over 11%. Mechanisms of rapid and uniform deposition of diamond films with low gas consumption and high carbon transition efficiency are discussed.

Effects of superimposed pulse bias on TiN coating in cathodic arc deposition

Orthogonal designs are used to investigate the main factors when doing experiments in which pulse bias is superimposed on d.c. bias during cathodic are deposition of TiN. Pulse peak, duty cycle, frequency, direct voltage, are current and pressure all are investigated when coating TiN on HSS substrates. Roughness, surface micrograph, microhardness and thickness are tested. By analysis of variance, it is shown that pressure and frequency are the main factors. R-a and droplet density of the film with (d.c. + pulse) bias decrease. A simple explanation for the result is suggested.

Arc Root Motions In An Argon-Hydrogen Direct-Current Plasma Torch At Reduced Pressure

Arc root motions in generating dc argon-hydrogen plasma at reduced pressure are optically observed using a high-speed video camera. The time resolved angular position of the arc root attachment point is measured and analysed. The arc root movement is characterized as a chaotic and jumping motion along the circular direction on the anode surface.

Arc Root Motion In An Argon-Hydrogen Dc Plasma Torch

Arc root motion on the anode surface of a dc non-transferred plasma torch was observed. Adding hydrogen changes the arc root attachment from a diffused type to a constricted type, and the arc root of Ar-H-2 plasma suddenly,jumps from one spot to another irregularly. Images of the arc root motions taken by a high-speed video camera are presented.

Effect of Surface Condition of Electrode on the Surface Melting of Material by Laser-Guided Micro-Arc Discharge

This paper studies the surface melting in the atmosphere by YAG laser-guided micro-arc discharge. In three kinds of surface conditions (free, oiled, and polyethylene covered), we try to control the diameter and the power density of discharge pit. It is found that the power density of 3 x 10(6) W/cm(2) of discharge pit on the oiled surface is moderate to form the melted layer thicker than that of the others, adapting to strengthen the surface of material, and the power density of 1.07 x 10(7) W/cm(2) of discharge pit on the polyethylene-covered surface is highest to form the deepest discharge pit among them, adapting to remove the material.

Comparative observation of Ar, Ar-H-2 and Ar-N-2 DC arc plasma jets and their arc root behaviour at reduced pressure

Results observed experimentally are presented, about the DC arc plasma jets and their arc-root behaviour generated at reduced gas pressure without or with an applied magnetic field. Pure argon, argon-hydrogen or argon- nitrogen mixture was used as the plasma-forming gas. A specially designed copper mirror was used for a better observation of the arc-root behaviour on the anode surface of the DC non-transferred arc plasma torch. It was found that in the cases without an applied magnetic field, the laminar plasma jets were stable and approximately axisymmetrical. The arc-root attachment on the anode surface was completely diffusive when argon was used as the plasma-forming gas, while the arc-root attachment often became constrictive when hydrogen or nitrogen was added into the argon. As an external magnetic field was applied, the arc root tended to rotate along the anode surface of the non-transferred arc plasma torch.