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21.
The tetragonal → monoclinic ( t → m ) martensitic phase transformation in ZrO2 –0.5–4 mol% Y2 O3 proceeds during isothermal aging at various temperatures from 350 to 800 K; i.e., the transformation increases sigmoidally with aging time. The time-temperature-transformation ( T - T - T ) curves show a typical C shape, with very high rate for lower Y2 O3 -content specimens, and the rate decreases with higher Y2 O3 content. The transformation temperature ( M s ) of the t → m transformation obtained from dilatation curves during the cooling stage coincides well with C curves above the nose temperature. The t → m transformation should occur isothermally, as suggested by a nucleation and growth mode. 相似文献
22.
We propose a computer-based framework for the formal verification of collaboration patterns in healthcare teams. In this, the patterns are constructed diagrammatically as compositions of keystones that are viewed as abstract processes. The approach provides mechanisms for ensuring that safety properties are enforced and exceptional events are handled systematically. Additionally, a fully verified, executable model is obtained as an end product, enabling a simulation of its associated collaboration scenarios. 相似文献
23.
《Journal of Visual Languages and Computing》2014,25(2):89-106
Complex software systems are often modeled using data flow diagrams, in which nodes are connected to each other through dedicated connection points called ports. The influence a layout algorithm has on the placement of ports is determined by port constraints defined on the corresponding node.In this paper we present approaches for integrating port constraints into the layer-based approach to graph drawing pioneered by Sugiyama et al. We show how our layout algorithm, called KLay Layered, progresses from relaxed to more restricted port constraint levels as it executes, and how established algorithms for crossing minimization and edge routing can be extended to support port constraints. Compared to the previous layout algorithms supporting ports, our algorithm produces fewer edge crossings and bends and yields pleasing results.We also explain and evaluate how layout algorithms can be kept simple by using the concept of intermediate processors to structure them in a modular way. A case study integrating our layout algorithm into UC Berkeley's Ptolemy tool illustrates how KLay Layered can be integrated into Java-based applications. 相似文献
24.
高砷铜精矿浸出液中因含砷较高存在砷害问题,砷回收利用具有重要的意义。研究针对某高砷硫化铜精矿除杂后的浸出液,探讨了以砷酸铜形式综合利用砷的热力学及工艺参数。绘制了Cu-As-H2O系电位-pH图,进行了砷酸铜制备工艺过程的热力学分析,对净化后的某高砷硫化铜精矿浸出液,以氨水为中和剂,当pH=5.0~8.0,温度80~90℃时,制得了CuAs2O4、C4H6As6Cu4O16、Cu5As2O10.5H2O、Cu5As4O15.9H2O、Cu2AsO4OH.3H2O及Cu2AsO4OH 6种不同结构的砷酸铜,沉砷后溶液中砷含量为9.11~35.82 mg/L。 相似文献
25.
The thermodynamics of the Ni-N system is poorly known from experiments, and there is a need of information on the stability of the various nitride phases and the Ni-N phase diagram. This kind of information has been obtained by us, by combining the few measurements available with predictions, based on recently reported regularities in bonding properties and vibrational entropy of 3d transition metal compounds. A calculated Ni-N phase diagram is presented. A certain range of homogeneity for the hexagonal nitride phase is obtained, which is comparable to that of other 3d transition metal-nitrogen systems. The question of the possible existence of a stable Ni4N phase is examined. According to our results, Ni4N is metastable in the Ni-N system. 相似文献
26.
为更好地适应集成电路产业的高速发展,针对传统的印刷电路板设计方法进行了改进,引入中心库并对其进行优化,同时在原理图设计和印刷电路板设计之间引入了一个公共数据库.实验结果表明:该方法在缩短印刷电路板的设计周期和降低设计成本方面有明显改善. 相似文献
27.
《Journal of the European Ceramic Society》2021,41(14):7005-7013
The lead-free piezoelectric material sodium bismuth titanate (NBT, Na0.5Bi0.5TiO3) has attracted considerable attention owing to its promising dielectric, piezoelectric, and electrical properties. However, the literature on the binary subsystems is contradictory and there are only limited data for the ternary system. The present work surveys all of the reports of the binary subsystems Bi2O3 – TiO2 and Na2O – TiO2 and synthesizes these data into inclusive revised versions. The compatibilities for the ternary system Na2O – Bi2O3 – TiO2 were determined experimentally, thus enabling the construction of a complete isothermal section at 800 °C. The compatibilities associated with the problematic binary subsystem Na2O – Bi2O3, which experiences extreme volatilisation, were determined through the generation of the absent standard-state thermodynamic functions for the relevant binary and ternary phases, thus providing a full suite of thermodynamic data for this system. The thermodynamic stability diagrams for Na2O, Bi2O3, and TiO2 thus were calculated. The isothermal section also addresses the contradictions in the literature concerning the formation of solid solutions of Bi12TiO20-x / Bi12-xTi1+xO20+0.5x, pyrochlore (Bi2Ti2O7 / NawBi2-xTi2-yO7-z), BTO (Bi4Ti3O12 / NaxBi4Ti3O12+0.5x), and NBT (Na0.5Bi0.5TiO3 / Bi1±xNaxTiO3.5±x). Further, it was observed that the congruent melting point of NBT, which was determined to be 1225 °C, was preceded by the onset of gradual structural destabilization at 940 °C. Also, the NBT rhombohedral → tetragonal phase transformation was observed at an onset temperature of ∼250 °C. The present work thus provides platform data for the fabrication and reactivities of materials in the ternary system Na2O – Bi2O3· TiO2 and its binary subsystems. 相似文献
28.
N. Venkaiah M.S. Shunmugam 《International Journal of Machine Tools and Manufacture》2007,47(7-8):1229-1236
The present work deals with evaluation of form error from the measured profiles obtained using a form tester, namely roundness/cylindricity measuring instrument. In Part I, details of circularity evaluation are presented. Due to eccentricity in component setting and radius-suppression inherent in the measurement, circularity error has to be evaluated with reference to a limacon. A computational geometry-based algorithm is proposed for establishing minimum circumscribed, maximum inscribed and minimum zone limacons. A new type of control hull for directly constructing equi-angular diagrams and a new procedure for updating are introduced. Validation has been done with bench-mark data set and corresponding results available in the literature. Being geometry-based algorithm, it is simple to follow and each iteration can be visualized and interpreted geometrically. On comparison with simplex search method, the proposed algorithm is found to be computationally efficient in terms of accuracy and time taken. The proposed methods can be easily implemented in computer-aided roundness measuring instruments. Extension of this work for evaluation of cylindricity error has been dealt in Part II. 相似文献
29.
Fe-8-12Cr ferritomartensitic steels are widely used in the power generation, petrochemical and nuclear industries where they
are subject to high operating temperatures and stresses. Resistance to creep deformation is therefore a critical materials
property. One method of providing creep resistance is to precipitate a fine homogeneous distribution of vanadium nitride (VN)
particles in the matrix. Maximizing this precipitation hardening effect requires a high nitrogen content, but this could cause
gas bubble formation during conventional fabrication processes. It is therefore necessary to determine how much N can be added
without encountering such problems. Phase stability calculations, using Thermo-Calc, were carried out to find high-N compositions
to optimize the fraction of VN and the fabrication route for obtaining fine particles. Several experimental compositions,
including nine high-nitrogen alloys, were fabricated as ingots; out of these, two exhibited porosity Thermo-Calc predicts
that, in all of the high-nitrogen alloys, nitrogen gas is a stable phase around the solidus temperature. It is evident that
porosity cannot simply be predicted from the presence of the gas phase on the equilibrium diagram. However, detailed analysis
of the equilibrium phases predicted in these alloys, including their variation with composition, allowed a porosity criterion
to be obtained. This criterion links porosity formation to the nature of the liquid-to-solid transformation. Further calculations
were carried out to predict the dependence of gas phase evolution on both composition and pressure. Thermodynamic calculations
are a valuable tool for the design of these industrially important alloys. Input from experimental data has enabled the refinement
of the initial design criteria such that it should now be possible to propose compositions with high VN hardening but without
the risk of porosity.
This paper was presented at the International Symposium on User Aspects of Phase Diagrams, Materials Solutions Conference
and Exposition. Columbus, Ohio, 18–20 October, 2004. 相似文献
30.
NEW METHODS FOR CALCULATING ACTIVITIES OF COMPONENTS FROM PHASE DIAGRAMS IN BINARY PERITECTIC SYSTEMS 总被引:3,自引:0,他引:3
Zhang Yongjun Hunan Superior Tech Materials Company Ltd. Changsha Zhang Xunying The Fourth Smelter Shuikoushan Mineral Bureau Henyang Fu Chongyue Department of Nonferrous Metallurgy Central South University of Technology Chang 《中国有色金属学会会刊》1997,(2)
NEWMETHODSFORCALCULATINGACTIVITIESOFCOMPONENTSFROMPHASEDIAGRAMSINBINARYPERITECTICSYSTEMS①ZhangYongjunHunanSuperiorTechMateri... 相似文献