The fate of injectant coal in blast furnaces: The origin of extractable materials of high molecular mass in blast furnace carryover dusts

The aim of the work was to investigate the fate of injectant coal in blast furnaces and the origin of extractable materials in blast furnace carryover dusts. Two sets of samples including injectant coal and the corresponding carryover dusts from a full sized blast furnace and a pilot scale rig have been examined. The samples were extracted using 1-methyl-2-pyrrolidinone (NMP) solvent and the extracts studied by size exclusion chromatography (SEC). The blast furnace carryover dust extracts contained high molecular weight carbonaceous material, of apparent mass corresponding to 10⁷?10⁸ u, by polystyrene calibration. In contrast, the feed coke and char prepared in a wire mesh reactor under high temperature conditions did not give any extractable material. Meanwhile, controlled combustion experiments in a high-pressure wire mesh reactor suggest that the extent of combustion of injectant coal in the blast furnace tuyeres and raceways is limited by time of exposure and very low oxygen concentration. It is thus likely that the extractable, soot-like material in the blast furnace dust originated in tars is released by the injectant coal. Our results suggest that the unburned tars were thermally altered during the upward path within the furnace, giving rise to the formation of heavy molecular weight (soot-like) materials.     

Lightning activity on the central Tibetan Plateau and its response to convective available potential energy

Lightning flash activities on the central Tibetan Plateau have been studied by using the satellite-based Lightning Imaging Sensor(LIS)database from January 1998 to July 2002.The lightning activity shows a clear diurnal variation on the central Plateau.The peak lightning activity appears at about 17:00 which is 3 h earlier than that in Jingxhou,Hubei in the same latitude belt nearby,indicating that the lightning activity is a sensitive indicator of solar heating on the Plateau.The lightning discharge is weaker on the Plateau than Jingzhou.Hubei and other low-altitude continental regions because of the lower convective available potential energy(CAPE)on the Plateau.The CAPE on the Plateau is 12 times lower than that in Jingzhou,Hubei,and 20 times lower than that in the sea-level region,such as Guangzhou and Florida.However,the sensitivity of lightning activity to CAPE changes on the Plateau is up to 30 times more sensitive than other prominent low-altitude regions.     

A carbon- and oxygen-isotope record of recent environ- mental change from Qinghai Lake, NE Tibetan Plateau

An understanding of natural climatic variability is essential for evaluating anthropogenic impacts on recent and future climate[1—3]. Due to the lack of lengthy instrumental records, such an understanding must be gained from natural archives of climate change. Palaeolimnological indicators of past lake levels may provide a sensitive record of changes in effective precipitation in closed basins. This approach is particularly relevant on the Tibetan Plateau, where instrumental records are very…     

Nanoengineering of Flux Pinning Sites in High－Tc Superconductors

Volume pinning forces were determined for a variety of bulk high-Tc superconductors of the 123-type from magnetization measurements. By means of scaling of the pinning forces, the acting pinning mechanisms in various temperature ranges were identified. The Nd-based superconductors and some YBCO crystals exhibited a dominating pinning of the δTc-type (i.e., small, superconducting pinning sites). In contrast to this, the addition of insulating 211 particles provided pinning of the δl-type; providing effective pinning in the entire temperature range acting as a “background” pinning mechanism for the peak effect. Due to the small coherence lengths of the high-Tc compounds, effective pinning sites are defects or particles of nanometer size relative to ε^3. Integral magnetic measurements of the magnetization as a function of temperature in large applied magnetic fields (up to 7 T) revealed that practically all high-Tccompounds were spatially inhomogeneous, which could becaused by oxygen deficiency (YBCO), solid solutions of Nd/Ba (NdBCO and other light rare earth compounds), intergrowths (Bi-based superconductors), and doping by pair-breaking dopants like Zn, Pr. This implies that the superconducting sample consists of stronger and weaker superconducting areas, coupled together. In large applied fields, this coupling gets broken and the magnetization versus temperature curves revealed more than one superconducting transition. In contrast, irradiation experiments by neutrons, protons,and heavy-ions enabled the artificial introduction of very effective pinning sites into the high-Tc superconductors, thus creating a large variety of different observations using magnetic data. From all these observations, we construct a pinning diagram for bulk high-Tc superconductors explaining many featuresobserved in high-Tc samples.     

南澳岛及其附近岛屿夏季鸟类的初步调查

作者一行于 2 0 0 1年夏季对南澳及其附近岛屿的鸟类资源状况进行了调查研究 .结果发现 ,南澳及其附近岛屿有鸟类 51种 ,隶属 1 3目 2 8科 ,其中雀形目 2 3种 ,占所发现种类的 45% ,非雀形目 2 8种 ,占 55% ;国家一、二级保护动物各一种 ,分别为 :白腹军舰鸟 (F regataandrewsi)和岩鹭 (Egretta sacra) .按鸟类的栖息和迁徙习惯划分 ,有海鸟 8种 ,湿地候鸟 2种 ,湿地留鸟 9种 ,陆地候鸟 4种 ,陆地留鸟 2 8种 .在所有鸟类中以褐翅燕鸥 (Sterna anae-thetus)为优势种 ,数量最大 ,分布最广 .     

Ni2MnGa铁磁形状记忆材料

铁磁形状记忆合金 (FSMA)是在一定温度范围马氏体相稳定同时又具铁磁性的一类特殊的形状记忆合金。Ni2MnGa铁磁形状记忆合金近年来成为呈现磁场驱动大应变的新型驱动材料 ,这些应变来自磁场诱发马氏体孪晶的重排 ,而不是磁场对奥氏体至马氏体相变的作用。孪晶变体的重排在宏观上呈现为正或切应变 ,一非化学计量比Ni2 MnGa单晶于室温加 0 .4T磁场能产生6 %的应变 ,Ni Mn Ga单晶在高至 15 0Hz的交变磁场仍可得到 2 .5 %的应变。本文阐述了与这种磁控形状记忆效应相关的孪晶界迁动的磁学和晶体学理论。马氏体相的大磁晶各向异性能使磁化沿c轴方向有利 ,穿过孪晶界c轴刚好转动 90度 ,同时 ,这个孪晶界也构成了约 90度的畴界。在各向异性的情况下 ,孪晶界的迁动仅有相邻孪晶变体的Zeeman能差驱动 ,μ0 ΔMis·Hi。磁场和外应力对应变的影响通过对一简单的自由能表达式取极小值来表示 ,自由能表达式包括Zeeman能、磁晶各向异性能和外应力以及在某些情况下需考虑的内部弹性能 ,模型的所有参数可通过应力 应变曲线和磁化曲线测量得到。铁磁形状记忆合金的磁场诱发应变可类比传统热弹性形状记忆效应 ,与更为人们所熟知的磁致伸缩现象不同。     

285℃条件下伊/蒙混层矿物的存在及其意义——新西兰现代活动地热区的研究

长期以来认为,蒙皂石的伊利石化程度主要受温度控制,伊/蒙混层矿物被广泛用作矿物地质温度计。作者在对新西兰Kawerau现代活动地热区进行有关粘土矿物水/岩反应的     

Design of Luenberger function observer with disturbance decoupling for matrix second-order linear systems-a parametric approach

1.INTRODUCTIONThere have been many approaches to disturbance de-couplinginlinear multivariable control systemdesign.Linnemann[1]proposed a numerically stable algorithmfor disturbance decoupling by measurement feedback.Van Der Woude[2]considered the combined problemof disturbance decoupling and stabilization by mea-surement feedback.Syrmos[3]proposed a numericallyefficient algorithm based on Sylvester equations forthe problemof disturbance decoupling with arbitrarypole placement usingstat…     

Adaptive control of system with hysteresis using neural networks

1.INTRODUCTIONThe piezoelectric actuators are well suited for micro-position devices in precision engineering because oftheir fast response,nanometer resolution and biggerdriving force[1].However,hysteresis inherent topiezoelectric actuator severely li mits system’s perfor-mance such as giving rise to undesirable accuracy oroscillations,even leading to instability.Hysteresischaracteristics are generally nondifferentiable andusually unknown.It is a difficult task to mitigate itsharmful ef…     

Fuzzy controller design for networked control system with time-variant delays

1.INTRODUCTIONAs a system becomes more and more intelligent andflexible,the systemrequires more sensors,actuators,and controllers,which are often referred to as fielddevices.In most cases,these field devices requiresome type of electrical connection because they aredistributed over a certain area.Conventionally thesedevices are connected with point-to-point connec-tions,whichis not suitable any more for modern in-dustrial control systems,because the number of cableis proportional tothe squ…