Papers by Keyword: Transformation

Abstract: High temperature flow curves were evaluated on two Nb steels in both compression and torsion and at a series of temperatures and strain rates. The critical strains for the initiation of dynamic transformation (DT) were determined by the double differentiation method. These are shown to be distinctly lower than those associated with dynamic recrystallization (DRX). It is also evident that the compression critical strains for both DT and DRX are lower than the equivalent torsion critical strains. Mean flow stresses (MFSs) were calculated by integration from the flow curves. When plotted against inverse temperature, stress drops were observed about 30 degrees above the Ae₃. These drops are shown to be caused by the dynamic transformation of austenite to ferrite, a softer phase. The characteristics of the ferrite produced dynamically are described and the transformation is shown to be displacive in nature, leading to the appearance fine Widmanstatten plates.

Abstract: We study the refinement operation of Petri net based Representation for Embedded Systems (PRES+). A refinement of Petri nets is an important transformation to preserve properties of original nets. For systems specified in PRES+, this paper proposes a kind of refinement operation for PRES+ and gives some conditions to preserve important properties, such as reachability, timing and functionality.

Abstract: The aim of this work was the microstructure and texture analysis of a deformed via cold-rolling 24.5Mn-3.5Si-1.5Al-Ti-Nb TWIP/TRIP type steel. It was found, that during cold plastic deformation a phase transformation of austenite into martensite takes place. The transformation progress was confirmed by the microscopic investigations. The texture of austenite is characterized by a limited α₁=||RD fibre and the γ=||ND fibre. The texture of austenite changed with increasing deformation rate. In the texture of deformed austenite the strongest orientation is the {110} Goss orientation, which belongs to the α=||ND orientation fibre. During cold plastic deformation γ→ε and γ→ε→α’ phase transformations as well as the deformation of γ, ε and α’ phases are taking place in the steel. The formed ε phase (hexagonal structure) also possesses a distinct texture.

Abstract: The continuous cooling transformation behaviors were researched on X70 pipeline steel through two pass deformation and non-deformed austenite using Gleeble-3500 thermal mechanical simulator, and static continuous cooling transformation curve and dynamic continuous cooling transformation curve were measured through thermal dilation method and metallographic method. The influence of cooling rate and deformation parameters on microstructure was analyzed. The results show that the hot deformation accelerates the acicular ferrite and polygonal ferrite phase transformation, increases the starting transformation temperature and the finishing transformation temperature significantly, and shifts the CCT curve moving upward to the left side corner. Acicular ferrite is obtained in practice using accelerated cooling rate after deformation Acicular ferrite can be obtained in wider range of cooling rates, and microstructure and island structure is finer through hot deformation.

Abstract: Cave dwelling is a typical traditional building form in the Loess Plateau of China. The thesis analyses the ecological characteristics of cave dwelling in Hougou village of Yuci from the green building perspective. It summarizes its strengths and shortages based on low carbon energy saving. The transformation methodologies include adding sunlight rooms, making high windows in the northern walls and adding vertical shaft for lighting and ventilation. This paper makes a comparative analysis on the inside thermal environment by using simulation software and aims to provide suggestions to the green building issues.

Abstract: Despite little research of them, the landscapes of Slender West Lake underpin a significant and unique typology among the various Chinese traditional urban waterfronts. Although the name ‘Gardens of Yangzhou’ appears in 11th century, these gardens were referred and used as urban public landscape from the 18th century because of Grand Canal. The article explores the organic evolution of Chinese traditional urban waterfronts, through an investigation of historical events occurring along with the landscapes of Slender West Lake. As a Chinese traditional urban waterfront, its organic evolution was often based on the transformation of the experience of landscape. When the trip was more based on the river because of boats, the edge of the garden has become the focus point.

Abstract: The present research was focused to investigate the effect of internal crucible design that influenced the 4H-SiC crystal growth onto a 6H-SiC seed by PVT method. The crucible design was modified to produce a uniform radial temperature gradient in the growth cell. The seed attachment was also modified with a use of polycrystalline SiC plate. The crystal quality of 4H-SiC single crystals grown in modified crucible and grown with modified seed attachment was revealed to be better than that of crystal grown in conventional crucible. The full width at half maximum (FWHM) values of grown SiC crystals in the conventional crucible, the modified seed attachment and the modified crucible were 285 arcsec, 134 arcsec and 128 arcsec, respectively. The micropipe density (MPD) of grown SiC crystals in the conventional crucible, the modified seed attachment and the modified crucible were 101ea/cm^2, 81ea/cm^2 and 42ea/cm^2, respectively.

Abstract: A constitutive model is developed for shape memory alloys (SMAs) based on the concept that an SMA is a mixture composed of austenite and martensite. The deformation of the martensite is separated into elastic, thermal, reorientation and plastic parts, and that of the austenite is separated into elastic, thermal and plastic parts. The volume fraction of each phase is determined with the modified Tanaka’s transformation rule. The typical constitutive behavior of some SMAs, including pseudoelasticity, shape memory effect, plastic deformation as well as its effects, is analyzed.

Abstract: Cell suspension cultures of Jatropha curcas were established and optimized in shake flasks. The stem segments of Jatropha curcas were taken as the explants for studying the techniques of callus induction and cell suspension cultures. The result shows that the optimal medium for callus induction is MS+2,4-D0.6mg/L+ BA1.0mg/L + Sucrose 30g/L, in which the callus is humid, loose and colorful. The fine suspension cell system have been established by inoculating the callus in the medium of MS+NAA0.2mg/L+2,4-D1.0mg/L+BA0.5mg/L for 13 days of cultivation, and the rotation speed should be lower than 120rpm in the culture of oscillation. QD-labeled chitosan-DNA complexes as nano transgenic system, using CdSe as bio-labels and chitosan-DNA(CS-DNA) as nano-scale genic carriers, were prepared and shown to have uniform particle sizes and superior fluorescence properties. Confocal laser scanning microscopy(CLSM) confirmed the target DNA from QD-labeled chitosan-DNA complexes was integrated into the plant cell and suggest the possibility of stable transformation in Jatropha curcas.

Abstract: AutoCAD is an accessorial desktop cartography software widely used in project cartography for its easy manipulation and data edit ability. GIS is a powerful tool of using computers to make dimensional with advantage of display, analysis, output and management of geographical data. The data of the two systems is not compatible and they need to be transformed for data sharing and application. This paper points out the difference of AutoCAD and GIS data, analyzes some common problems during the data transforming process and introduced the experimental study which takes example for transforming the CAD forestry map of Buyunshan country, Dalian city to ArcView geographical information system. The objective of this paper was trying to find an effective way for the transformation from CAD graphics files to geographical information system.