某火电厂磨煤机高速轴断裂失效分析及预防措施

贵州某电厂磨煤机的高速轴在运行过程中发生断裂，通过金相组织分析、化学成分分析及硬度试验等方法，断裂失效的主要原因：非金属夹杂物含量较多，锻造比不够，带状组织及成分偏析导致开裂。     

粉末X-射线衍射谱图的计算机物相分析

由国内自主开发，以X-射线衍射标准数据库为基础，比较完善及可靠的计算机物相分析系统仍不多见，随着我国加入WTO，开发一套拥有自主智产权的识别系统变得十分重要。本程序以ICDD（国际晶体粉末衍射中心）的PDF2文件（粉末衍射文件）作为标准数据库，以Microsoft Visual C 6.0为开发工具，程序为Windows界面，采用向导式设计，具有谱图显示功能，改变了以往同类程序DOS界面不友好、速度慢、匹配不够准确及其它诸多缺点，并且多处使用人机对话方式，用户既可以让程序自动识别又可以根据经验，人工参与来提高识别准确度。本程序主要采用3，6，9强峰匹配筛选，元素及全谱图对照等手段。经程序计算与识别后，会将所有匹配上的记录以列表及谱图形式列出以供使用者参考，并且引入兼容性概念，将最终匹配上的记录加以组合，以确定物相组成，并且进行评分及计算各组分的粗略百分比组成，最终组合出结果，以谱图形列出。它具有速度快、匹配准确等优点，能明确指出样品的物相构成。     

Claus硫磺回收工艺中硫蒸气的平衡组成计算

本文根据最小自由能法原理建立了计算硫蒸气平衡组成的数学模型。此模型的计算值与实验值符合较好。模型已编成程序,计算时直接由程序赋初值,此程序可供 Claus 硫磺回收工艺设计用。     

静态数据流机操作开销的计算

本文提出静态数据流计算机和数据流图的模型,再由此建立计算数据流计算机中指令操作开销与并行度相互关系的模型。根据这一模型对具有各种并行度的程序进行计算,求出程序运行时实际并行度与指令操作开销的关系。由此得出结论,当程序一定时,它在一个系统上运行的实际并行度是由系统中指令操作开销唯一决定的,即为MP/(OH+1)(MP是程序的平均并行度,OH为指令平均操作开销)。因此,在数据流计算机中,操作开销对系统性能有着严重的影响。     

微型汽车五自由度模型动态仿真

本文建立了微型汽车五自由度的动力学模型．在推导计算公式的基础上编制了仿真计算程序，并以北京２０２０Ｓ为例做了动态模拟计算和平顺性、安全性的预测．提出了优化阻尼值。本程序使用简单，应用范围广．配以作者的优化程序后．具有相当好的实用性。     

《啊！我想到了》专栏参考答案

通常，快速随意按键时重复击打同一字母的概率会大大减少。可以编写循环语句程序，通过计算文件中重复字母连续出现的频率来判断文件是由随机函数产生还是由手工输入。     

用程序计算器PC-1500绘制晶体结构模型立体图

在结构化学教学中,通过晶体模型树立空间概念是教好、学好晶体结构部分的一个重要方面。本文介绍的方法,可以根据一个晶胞模型中代表性球的坐标,方便地用程序计算器pc—1500绘制出晶胞的彩色立体图形,从而有助于学生对晶体结构的熟悉与掌握。我们已用此方法绘制出了七个品系,十四种布拉威晶格,AB型、AB_2型二元化合物的典型结构,以及更复杂的晶体结构模型的立体图。绘制原则大致如下:     

后过渡金属催化剂的分子模拟研究

应用量子化学计算程序ADF考察含有不同有机配体的过渡金属镍配合物对催化乙烯聚合反应的作用，对由于取代基不同造成催化活性不同的相关机理进行验证计算；应用分子动力学计算程序考察催化剂失活难易程度，应用量子化学计算程序ADF考察聚合分子双键位置及支化度的变化情况，计算结果表明当吡叮环配体中有甲基取代时，反应活性降低。当苯环上1，3，5位出现甲基取代时；反应不易发生。当配体上有较强的给电子基团取代时，反应活性增强。     

离子选择电极应用于沉淀反应溶度积的测定——苯札溴胺—TPB和服止宁—TPB等缔合物的Ksp

离子选择电极电位法测定沉淀的溶度积的方法多为测出离子活度按活度乘积直接进行计算。作者在前文中介绍了利用滴定曲线方程式和最小二乘计算处理求得溶度积和等当点的方法。本文用自制的苯扎溴胺药物电极和服止宁药物电极,测定了它们与四苯硼钠形成缔合物沉淀的K_(sp),还用铜、铝离子电极测定了邻氨基苯甲酸和铜铁试剂与Cu~(2+),pb~(2+)离子生成沉淀的K_(sp)。用回归程序进行数据处理得到了满意的结果。     

微平面模型与经典混凝土理论模型的比较

针对在混凝土非线性分析时所采用的宏观本构模型中,没有考虑混凝土软化阶段或考虑不当,以及在多轴受力情况下宏观模型不能很好地模拟混凝土受力状态的问题,基于微平面理论,利用MATLAB编写混凝土材料的非线性本构关系程序,从理论和计算结果两方面与经典的基于应力张量及其不变量的本构模型进行比较.比较结果表明,在弹性变形阶段,经典理论模型和微平面模型计算结果与试验结果无明显区别;在非弹性变形阶段,经典理论模型与微平面模型有较大的差异,后者与试验结果吻合较好.微平面理论在混凝土三向受力和软化阶段更能准确地描述混凝土材料本构关系,且本构关系更简单、清晰.     

Modeling the viscosity of silicate melts containing zinc oxide

Our recently developed model for the viscosity of silicate melts is applied to describe and predict the viscosities of oxide melts containing zinc oxide. The model requires three pairs of adjustable parameters which describe the viscosities in three systems: pure ZnO, ZnO-SiO₂ and ZnO-Al₂O₃-SiO₂. The viscosity of multicomponent silicate melts containing ZnO is then predicted by the model without any additional adjustable model parameters. Experimental viscosity data are reviewed for melts formed by ZnO with SiO₂, Al₂O₃, PbO, CaO, MgO, Na₂O and K₂O. The deviation of the available experimental data from the viscosities predicted by the model is shown to be within experimental error limits.     

Modeling the viscosity of silicate melts containing Fe oxide: Fe saturation condition

Our recently developed model for the viscosity of silicate melts is applied to describe and predict the viscosities of oxide melts containing iron oxide. In the present study, the viscosity experimental data under the reduced atmosphere, which is Fe saturation condition were critically reviewed and three pairs of adjustable model parameters related to ‘FeO’ were optimized to best reproduce all experimental data in the FeO–SiO₂–Al₂O₃–CaO–MgO–Na₂O–MnO–Ti₂O₃–TiO₂ system. The viscosities of a wide compositional and temperature range of binary, ternary and multicomponent melts were well reproduced by the present model within the scatter of experimental data.     

A model for multicomponent diffusion in oxide melts

A general flux equation for multicomponent diffusion in oxide melts is presented. An explicit method was developed to calculate the gradients of single-ion activities from those of oxides with the constraints of local equilibrium and electroneutrality. This resolves ambiguity in quantifying the thermochemical driving force for ionic diffusion. A model equation for multicomponent ionic diffusion was derived within the framework of non-equilibrium thermodynamics by de Groot and Mazur. The proposed model takes empirically measurable quantities as input variables, so the diffusion calculations are consistent with thermochemical data, as furnished by the CALPHAD (CALculation of PHAse Diagrams) method, as well as ionic mobility measurements. Although the model is derived for oxides, it can be applied to diffusion in other concentrated liquid electrolytes, such as chloride and fluoride melts. Formulas for multicomponent ionic diffusion in various reference frames are presented with respect to mole fraction.     

Steelmaking technology for a sustainable society

For the reduction of CO₂ emission, two major developments are being conducted in COURSE50 (“ CO₂ Ultimate Reduction in the Steelmaking Process by Innovative Technologies for Cool Earth 50”). The one is separation of CO₂ gas from BFG (Blast Furnace Gas) and recharge of the rest of BFG including H₂ and CO into blast furnace. Hydrogen iron ore reduction technology is also going to be developed. The other one is amplification of H₂ gas from CH₄, for example, in COG (Coke Oven Gas). The produced hydrogen gas will be supplied to the society or the reformed COG will be charged to blast furnace. In addition to these drastic challenging technology developments, a variety of measures for CO₂ reduction is under taken. In the frame of Asia-Pacific Partnership on Clean Development and Climate, the best available technology for energy savings are discussed to be transferred within seven member nations, which has the effect of 1.27 million ton reduction of CO₂ emission a year. By supplying energy saving steel products to society such as high strength steels for automobiles and ships, which realizes the fuel consumption reduction, high performance electrical steels for motors and transformers, which realize electricity loss reduction, and by recycling waste city plastics and tires in steel processes for hydrogen gas generation, chemical raw material conversion and iron ore reduction, etc., it is expected that equivalent 10% reduction of CO₂ gas emission in steel production is counted. In steelmaking process the reduction of refining slags contributes materials use efficiency and less emission of unuseful byproducts. The control and utilization of nonmetallic inclusions, such as deoxidation products, are one of the key technology for obtaining product performance, which is required in the above-mentioned steel products. In order to optimize steelmaking process for these purposes, computational thermodynamics is applied. Optimization of demanganization, and control of chemical composition of nonmetallic inclusions by the use of computational thermodynamics are mentioned.     

A thermodynamic model for carbon trapping in lattice defects

A thermodynamic model in the framework of the CALPHAD method is proposed to describe the distribution of interstitial solute (carbon) atoms in bcc-iron during tempering of martensite. In the model, the crystal defects are introduced as a separate sublattice, which is a highly favored lattice position for carbon compared to undisturbed interstitial sites or precipitate sites in cementite. With the model, which is convenient for multicomponent, multiphase systems, the fraction of carbon atoms trapped by the defects during tempering can be calculated. It is demonstrated that, when martensite is heavily dislocated, the precipitation of cementite on tempering is greatly suppressed because the high dislocation density provides a sufficient number of stressed sites which can trap most of the carbon atoms. The calculations for an alloy steel show that, unlike cementite, the defect density and carbon trapping phenomenon influence the precipitation of stable carbides only marginally.     

The Cr-Nb-Si system: Improved thermodynamic modelling and its use in simulation of Laves phase in steel

Thermodynamic modelling of the Cr-Nb-Si ternary system is revised considering new findings in the binary Cr-Nb and extension to multicomponent systems. Thermodynamic model parameters of intermetallic phases are re-optimized based on density functional theory (DFT) calculations and experimental data. Particular attention was given to the transformations of Laves phase polytypes (i.e. C14 and C15). The calculated phase stabilities of technologically relevant Laves phase polytypes C14 and C15 are discussed. Their extension to multicomponent systems is tested for typical steel grades used in high-temperature applications. C14 is the dominant phase in high Cr ferritic steel.     

Mathematical and software support of calculation and optimization of multicomponent raw mixes

Formalization of methods of calculation and optimization of multicomponent raw mixes in silicate production engineering is proposed. It allows one to proportion raw mixes with an unlimited number of components using any combinations of demands concerning the raw mixes being used and the product to be obtained and to take into account any number of additives and doping agents. The structure of the information support and an algorithm of calculation and optimization of multicomponent raw mixes are described. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 141–148, March–April 2006.     

Modified general solution model for interstitial solid solution

By introducing two sublattices to the general solution model, a modified model for studying the thermodynamic properties of interstitial solid solutions in multicomponent steels is suggested. The excess Gibbs free energy of mixing in Fe-Σi-C steel can be calculated from the modified model with the thermodynamic parameters of ternary Fe-i-C and binary i-j systems that are easily obtained. As an example, Ae₃ temperatures for pro-eutectoid ferrite formation in nine steels have been calculated from the modified general solution model and compared with that from the two-sublattice model using the interactions among multicomponents or not and that from ThermoCalc software. The relative standard deviation and root-mean-square error between the experimental Ae₃ temperatures and the values calculated from the modified model are 0.57% and 7.2K, respectively. It can be concluded that the modified general solution model for interstitial solid solutions is acceptable.     

Overview of the applications of thermodynamic databases to steelmaking processes

Computerized thermodynamic databases for solid and liquid steel, slags and solid oxide solutions, for large numbers of components, have been developed over the last three decades by critical evaluation/optimization of all available phase equilibrium and thermodynamic data. The databases contain model parameters specifically developed for molten slags, liquid and solid steel and solid oxide solutions. With user-friendly software, which accesses these databases, complex chemical reactions and phase equilibria occurring throughout the steelmaking process can be calculated over wide ranges of temperature, oxygen potential and pressure. In the present article, the thermodynamic models and databases for molten slag and liquid steel included in well-known thermochemical packages and their applications to complex steelmaking processes involving molten slag, steel, inclusions, refractories and gases are reviewed.