Thermodynamic optimization of the binary PbO–CaO and ternary PbO–CaO–SiO2 systems

Liquidus phase equilibrium data from the recent study for the PbO–CaO and the PbO–CaO–SiO₂ systems (as a part of research program on the characterization of the multicomponent PbO–ZnO–FeO–Fe₂O₃-“Cu₂O”-CaO-SiO₂ system), combined with phase equilibrium and thermodynamic data from the literature, have been used to obtain a self-consistent set of parameters of the thermodynamic models for all phases: liquid, (Ca,Pb)₂SiO₄, (Ca,Pb)₃SiO₅, (Ca,Pb)SiO₃ (wollastonite and pseudowollastonite), Pb₃(Ca,Pb)₂Si₃O₁₁ (ganomalite) solutions, SiO₂ (quartz, tridymite, cristobalite), Ca₃Si₂O₇ (rankinite), CaO (lime), PbSiO₃ (alamosite), Pb₂SiO₄, Pb₁₁Si₃O₁₇, Pb₅SiO₇ lead silicates, PbO (massicot), Ca₂PbO₄, Pb₈CaSi₆O₂₁ (barysilite), PbCa₂Si₃O₉ (margarosanite) and Pb₃Ca₁₂Si₅O₂₅ compounds. Analysis of available data has shown the lack of data in the two immiscible liquids range over cristobalite, where several new experiments were done to support the model. The modified quasichemical model is used to describe the liquid slag phase. From these model parameters, the optimized ternary phase diagram is back calculated.     

Thermodynamic optimization of the binary CaO–ZnO and ternary CaO–ZnO–SiO2 systems

Liquidus phase equilibrium data of the present authors for the CaO–ZnO–SiO₂ system (as a part of research program on the characterization of the multicomponent PbO–ZnO–FeO–Fe₂O₃-“Cu₂O”-CaO-SiO₂ system), combined with phase equilibrium and thermodynamic data from the literature, have been used to obtain a self-consistent set of parameters of the thermodynamic models for all phases. The modified quasichemical model is used for the liquid slag phase; lime (Ca,Zn)O, zincite (Zn,Ca)O, α- and α′-dicalcium silicate (Ca,Zn)₂SiO₄ and tricalcium silicate (Ca,Zn)₃SiO₅ are described within Bragg-Williams formalism; tridymite, cristobalite SiO₂, wollastonite, pseudowollastonite CaSiO₃, rankinite Ca₃Si₂O₇, willemite Zn₂SiO₄, melilite (hardystonite) Ca₂ZnSi₂O₇ and Ca–Zn feldspar CaZnSi₃O₈ are treated as stoichiometric compounds. From these model parameters, the optimized ternary phase diagram is back calculated.     

f—CaO智能快速测定仪

介绍一种新的测定水泥熟料中 f-CaO 含量的智能快速测定仪,采用电导分析法,即测量溶液中的电导值,以求得溶液中某一物质的浓度。由单片机组成智能快速转换仪表系统,完成电导率与 f-CaO 含量的测量、转换以及显示、实现快速准确地测定水泥熟料中 f-CaO 的百分含量。     

常温CaO烟敏元件的研究

本文研究了以 SnO_2为基质材料,加入微量 CaO 的常温气敏元件(简称常温 CaO 元件)。该元件对10%～30%的烟有很好的选择性,并且灵敏,对丁烷、煤气、液化石油气、乙醇、氢气等不灵敏.本文讨论了 Sb_2O_3对常温 CaO 元件性能的影响。     

Thermodynamic assessment of the CaO–Cu2O–FeO–Fe2O3 system

Thermodynamic assessment of the CaO–Cu₂O–FeO–Fe₂O₃ system is presented. Effects of temperature and P(O₂) on the phase equilibria involving slag, solubility of copper and the Fe³⁺/Fe²⁺ ratio in slag have been modeled using available experimental data. Subsolidus phase equilibria and concentration of iron in liquid copper were evaluated as well. Different ways of representing phase equilibria in a quaternary system are illustrated. The slag model, [Ca²⁺, Cu⁺, Fe²⁺, Fe³⁺][O²⁻], was developed using the Modified Quasichemical Model (MQM). Liquid metal phase is modeled using the MQM, but as a separate solution, (Cu^I, Fe^II, O^II). Spinel phase is modeled using the Compound Energy Formalism (CEF) and takes into account the solubility of copper and calcium. A thermodynamic database produced in the present study can be used for predictions in pyrometallurgical processing of copper involving calcium ferrite slags. The database is internally consistent with the binary and ternary sub-systems published earlier, as well as with higher-order systems. It works in the environment of FactSage, ChemApp, ChemSheet and SimuSage software packages.     

Application of the Hoch-Arpshofen model to the SiO2CaOMgOAl2O3 system

The Hoch-Arpshofen model was applied to the SiO₂-CaO-MgO-Al₂O₃ system. First the binary interaction coefficients, obtained from the six binary systems, were used to calculate the Gibbs energy of formation of the ternary compounds present in the four ternary systems; then the calculated activities of SiO₂, CaO, and Al₂O₃ were compared with the measured activities. The calculated Gibbs energies of formation of anorthite, gehlenite, and cordierite agree with the measured energies; the measured enthalpies of formation of akermanite, diopside, merwinite, and monticellite must be multiplied by 0.568 ± 0.031 to obtain agreement. The Gibbs energy of formation of 3CaO-MgO-2Al₂O₃ was also calculated. The calculated activity data agree with some authors' measurements and not with others.     

Experimental study and thermodynamic optimization of the ZnO–FeO–Fe2O3–CaO–SiO2 system

Liquidus phase equilibrium experimental data from the present study for the ZnO-“Fe₂O₃”-CaO-SiO₂ system in air, combined with phase equilibria and thermodynamic data from the literature on the ZnO-“Fe₂O₃”-CaO system in air and ZnO-“FeO”-CaO-SiO₂ system in equilibrium with metallic Fe, have been used to obtain a self-consistent set of parameters of the thermodynamic models for all phases in the ZnO–FeO–Fe₂O₃–CaO–SiO₂ system. The modified quasichemical model is used for the liquid slag phase; spinel (Fe,Zn,Ca)^tetr (Fe,Zn,Ca,Va)^oct₂O₄, melilite Ca₂(Fe²⁺,Fe³⁺,Zn)(Fe³⁺,Si)₂O₇ and olivine (Fe,Zn,Ca)^I(Fe,Zn,Ca)^IISiO₄ are described with compound energy formalism; lime and wustite (monoxide) (Ca,Fe,Zn)O, zincite (Zn,Fe,Ca)O_1+x, calcium-zinc ferrites Ca₂Fe₂O₅-“CaZnO₂” and CaFe₄O₇-“ZnFe₄O₇”, α- and α′-dicalcium silicate (Ca,Fe,Zn)₂SiO₄ and tricalcium silicate (Ca,Fe,Zn)₃SiO₅ and silicoferrite of calcium (SFC) Ca₉Fe₄₆SiO₈₀–Ca₁₂Fe₄₀Si₄O₈₀ are described within Bragg-Williams formalism; for other phases, previous assessments have been adopted. The phase diagrams are back calculated with the optimized model parameters. Present study is a part of research program on the characterization of the multicomponent PbO–ZnO–FeO–Fe₂O₃-“Cu₂O”-CaO-SiO₂ system.     

基于CaO引导的甲烷蒸汽重整化学链燃烧制氢系统

为在重整气中得到高纯H_2和降低尾气CO_2分离成本,建立了基于CaO引导的甲烷蒸汽重整化学链燃烧制氢系统,该系统在重整反应器中加入CaO吸收剂,用以吸收重整器内的CO_2,提高重整气中H_2浓度,形成的CaCO_3固体在煅烧器中受热分解重新生成CaO。利用Aspen Plus进行了过程模拟及热力学分析,并研究主要参数对系统性能的影响,得到优化的操作条件为:CaO循环量/CH_4比为0.5,CH_4(燃料)/CH_4比为0.35,NiO循环量/CH_4比为1.4。CaO循环量/CH_4比从0变化到0.5时,重整气中H_2浓度从0.60增长到0.99;CH_4(燃料)/CH_4比在0.25~0.45区间变化时,重整气中H_2浓度从0.86提高到0.99,产气量增加;NiO循环量/CH_4比在1~1.6区间变化时,重整气中H_2浓度从0.88增长到0.99,系统有效能效率变化较小。     

Thermodynamic assessment of the CaO–P2O5–SiO2–ZnO system with special emphasis on the addition of ZnO to the Ca2SiO4–Ca3P2O8 phase

The CaO–P₂O₅–SiO₂–ZnO system including all binary and ternary sub-systems has been thermodynamically assessed using all available experimental data. Particular attention was given to the phase C2S–C3P which forms a complete solid solution with end-members α-Ca₂SiO₄ and α′-Ca₃P₂O₈. In addition, the present modelling of the phase C2S–C3P allows the inclusion of experimentally determined solubility values of zinc oxide in both end-members of the phase C2S–C3P. The mutual solubility between different crystallographic modifications of calcium and zinc phosphates is also described in this work using available experimental data. 24 phospates as stoichiometric phases have also been included in the database.     

钙[Ca(NO3)2和CaO]对茶树氟吸收的影响

通过水培和土壤盆栽试验,研究了Ca对茶树F吸收的影响。结果显示,在含F溶液中添加Ca显著降低茶树对F的吸收。在土壤盆栽试验中也得到了类似结果,在2种土壤F含量条件下,加入Ca(NO3)2后显著降低茶树成熟叶和新梢F含量。同样土壤加入CaO后,显著降低茶树对F的吸收。土壤分析表明加入Ca(NO3)2后并没有显著改变土壤水溶性F含量,而加入CaO后还增加了土壤水溶性F含量。因此,Ca减少F吸收可能并不单纯是因为形成CaF2后降低土壤F的有效性。     

Phase equilibria of the Al2O3–CaO–SiO2-(0%, 5%, 10%) MgO slag system for non-metallic inclusions control

Al₂O₃–CaO-(MgO–SiO₂) inclusions are one of the dominant inclusions in Al-deoxidized spring steel, the compositions changes of which are closely related to refining slags and deoxidization process. The Al₂O₃–CaO–SiO₂–MgO system can represent the primary ingredients of the Al₂O₃–CaO inclusions. According to analyzed compositions and predicted liquidus temperature ranges of inclusions and refining slag, equilibra experiments under high temperature, water quenching technique and subsquent electron probe X-ray microanalysis (EPMA) has been conducted to ascertain detailed thermodynamic database for inclusions control. Liquidus temperatures within the dominant phase fields of Ca₃SiO₅, Ca₂SiO₄, CaAl₂O₄, Ca₃Al₄O₉, spinel and MgO with the intervals of 20 °C from 1350 to 1560°C were identified. To further promote inclusions control, the influences of mass ratios of Mass(Al2O3)Mass(Al2O3+SiO2+CaO) and MgO contents on equilibrated phases and liquidus temperature changes have been explored. To further enhance modification levels of Al₂O₃–CaO-(MgO–SiO₂) system inclusions, it is suggested that refining time could be suitably prolonged.     

Some applications of matrices to location of zeros of polynomials†

In previous papers classical theorems on location of zeros of a polynomial with respect to the left half plane Γ₁ or the unit circle Γ₂ have been reformulated more simply in terms of appropriate companion matrices. It is shown how this work can be extended to the problem of zero location with respect to more general regions Γ of the complex plane. The first approach is to apply the bilinear transformation to the given polynomial, so that for example Γ₁ can be mapped into Γ₂ and a matrix representation of this is derived. An alternative method is discussed which relies on transformation of Γ into Γ₂. Some examples illustrate how any theorem involving Hurwitz-typc minors can be expressed in companion matrix terms, with a consequent halving of the orders of the determinants involved.     

Measurement of the Kernels of a Non-linear System of Finite Order†

A method of measuring the Volterra kernels of a finite-order non-linear system is presented. The kernels are obtained individually as a multi-dimensional impulse response. The multi-dimensional kernel transforms also can be obtained by the method described. As an extension, a technique of obtaining the Volterra kernels from a multi-dimensional step response is presented. This technique is useful for non-linear systems which can be considered to be of a given finite order for only a limited range of input amplitudes.     

The Implementation of Graphic Display of FAS

The principle of the fire alarm system and the implementation techniques of its computer graphic display are presented. With the help of the designing thoughts and technology of OOP, a Fire Alarm System (FAS) has been developed by using visual C++ language. The system has been put into use in many important buildings and has played an important role in monitoring and controlling the fire.     

Visualization of curvature plots and evaluation of fairness: an analysis of the effect of ‘scaling’

Changing the aspect-ratio (scale) of a graphical plot significantly affects the “messages” getting across to a viewer. This is true also for curvature plots and other graphs currently used in Curve & Surface Modeling to evaluate fairness. In particular, the sharp corners appearing in such graphs, employed as local fairness indicators by current practices, are significantly affected by nonuniform scaling. A detailed study of this phenomenon is presented offering specific guidelines for correctly “reading” curvature plots.     

Optimization of linear systems of constrained configuration†

For the sake of simplicity it is often desirable to restrict the number of feedbacks in a controller. In this case the optimal feedbacks depend on the disturbance to which the system is subjected. Using a quadratic error integral as a measure of the response, three criteria of optimization are considered :

1. The response to a given initial disturbance.

2. The worst response to an initial disturbance of given magnitude.

3. The worst comparison with the unconstrained optimal system.

It is shown that for each of these criteria the gradient with respect to the feedbacks can be calculated by a uniform method. The solution may then be found either directly or by a descent procedure. The method is illustrated by an example.     

Stabilization of a class of switched nonlinear systems

The stabilization of a class of switched nonlinear systems is investigated in the paper. The systems concerned are of （generalized） switched Byrnes-Isidori canonical form, which has all switched models in （generalized） Byrnes- Isidori canonical form. First, a stability result of switched systems is obtained. Then it is used to solve the stabilization problem of the switched nonlinear control systems. In addition, necessary and sufficient conditions are obtained for a switched affine nonlinear system to be feedback equivalent to （generalized） switched Byrnes-Isidori canonical systems are presented. Finally, as an application the stability of switched lorenz systems is investigated.     

Evaluation of Fourier transform of impulse response of linear time invariant systems†

Evaluation of the Fourior transform of the system impulse response is an important aspect of the design of control systems. A method suggested hero requires only one cycle of sine or cosine wave to be applied as an input to the system. It is proved that the sum of the sampled values of the output response, at the sampling interval equal to the period of the input wave, directly yields the sign and cosine transforms respectively. The procedure is generalized to any number of complete cycles of input wave, as well as to n/2 cycles whore n is any odd positive integer.