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Algorithm for Computation of Unstructured Real Stability Radius and Its Applications

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International Journal of Minerals,Metallurgy and Materials 1998年第4期12卷 245-250页

作者： Xiaodan Zhang Lequan Min(Applied science School, University of science and technology Beijing, Beijing 100083, China) Applied science School University of Science and Technology Beijing Beijing 100083 China

An algorithm for the computation of the unstructured real stability radius of high dimensional linearsystem is presented. Using the accurate formula of the real stability radius of 2-dimensional system linear systemchecks the algorithm. The result shows that the algorithm is reliable and efficient. As applications, the unstructuredreal stability radii of 2-dimensional Chua's circuit and 3-dimensional piecewise-linear system are calculated, thedynamical orbits of the corresponding perturbed systems are simulated.

关键词： lincar systems stability robustness parameter perturbation computational methods

β-Sialon Produced by Carbon Thermal Nitriding Reaction of Bauxite

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International Journal of Minerals,Metallurgy and Materials 2000年第3期14卷 209-213页

作者： Jun Wang, Nan Li, Caicheng Shi, Chengchang Jia ( Material science and Engineering School, University of science and technology Beijing, Beijing 100083, China Material science and Engineering School, Wuhan University of science and technology, Wuhan 430 Material science and Engineering School University of Science and Technology Beijing Beijing 100083 China Material science and Engineering School Wuhan University of Science and Technology Wuhan 430081 China

β-Sialon was produced by carbon thermal nitriding reaction in N_2 gas atmosphere when the mixtures of bauxite and anthracite were put into vertical furnace. According to the mass loss of raw materials and the result of X-ray diffration (XRD) of products, the influences of the process parameters on the compositions and relative contents of products, such as the fixed carbon content, the flow of N2, the soaking time and the temperature, were researched.

关键词： β-Sialon bauxite anthracite carbon thermal nitriding processing parameter vertical furnace

Distribution of Nb atom in the TiAl+Nb system

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Rare Metals 2001年第1期20卷 5-12页

作者： Xiaodong Ni, Xidong Hui, Guoliang Chen (Applied science School, University of science and technology Beijing, Beijing 100083, China State Key Laboratory for Advanced Metals and Materials, University of science and technology Beijing, China) Appl. Sci. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Based on MEAM (the modified embedded atom method) potential and an average atom model similar to B-W (Bragg-Williams) method, the distribution of Nb atoms in TiAl+Nb compounds with various composition was calculated. The calculation results showed that Nb atoms prefer to occupy the Ti sublattice of L10 structure for all compounds in question. With increasing atomic fraction of Nb and Al, Nb atoms exhibited a trend of ordered distribution on the Ti sublattice and result in a new L10 derivative superlattice structure.

关键词： Computer simulation Intermetallics Superlattices Ternary systems

Quasi-physical global optimization method for solving the equal circle packing problem

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science China(Information sciences) 2011年第7期54卷 1333-1339页

作者： HUANG WenQi & YE Tao School of Computer science and technology,Huazhong University of science and technology,Wuhan 430074,China School of Computer science and technology Huazhong University of Science and Technology

The equal circle packing problem is a well-known challenge in *** is also a natural,clear and fair test system for global *** paper presents a quasi-physical global optimization algorithm for solving the equal circle packing *** algorithm simulates two kinds of movements of N elastic disks: smooth movement driven by elastic pressures and violent movement driven by strong repulsive forces and attractive *** smooth movement makes the disks reach a locally optimal configuration,while the violent movement makes them jump out of the local optimum trap and reach a more promising *** algorithm is tested on the widely studied instances of N = 1,2,...,*** find better packings than the reported best-known ones on 37 instances and reproduce the best-known results on the remaining 113 instances.

关键词： equal circle packing global optimization quasi-physical method heuristic

Special Orientation Relationships Observed at the Early Stages of Recrystallization in Pure AlMn Alloy

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International Journal of Minerals,Metallurgy and Materials 1998年第3期12卷 140-146页

作者： Ping Yang(Material science and Engineering School, University of science and technology Beijing, Beijing 100083, China)(Institute for Metal science and Metal Physics, Aachen University of technology, D-52056, Aachen, Germany) Material science and Engineering School University of Science and Technology Beijing Beijing 100083 China Institute for Metal science and Metal Physics Aachen University of Technology D-52056 Aachen Germany

Electron Back Scattering Diffraction (EBSD) technique in a SEM was used to obtain local orientationalinformation on new grains and their surrounding deformed matrices at the early stages of recrystallization in pureA1-1 .3%Mn alloy. Results show that special orientation relationships including twin-relationship often exist betweennew grains, between new grains and deformed grains or between deformed grains. The occurrence of such specialorientation relationships is attributed to the special deformation behavior in the samples with large initial grain *** formation of recrystallization twins is discussed in a different way to those of traditional ones.

关键词： Orientation relationship recrystallization AlMn, EBSD

Nonlinear Theory on Dynamic Controlling Interface Patterns DuringSolidification of a Dilute Binary Alloy

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International Journal of Minerals,Metallurgy and Materials 1999年第4期13卷 253-258页

作者： Zidong Wang Hanqi Hu(Material science and Engineering School, University of science and technology Beijing, Beijing 100083, China) Material science and Engineering School University of Science and Technology Beijing Beijing 100083 China

In non-equilibrium nonlinear region, the nonlinear equations of time dependence of perturbation amplitude at the solid/liquidinterface during solidification of a dilute binary alloy are established on the base of assuming that there is local equilibrium at the solid/liquid interface and considering that curvature, temperature and composition at the solid/liquid interface which are related to the perturbation amplitude are nonlinear. As a result, patterns at the solid/liquid interface during solidification process, which is from nonsteadystate to steady state can be controlled by these nonlinear equations.

关键词： nonlinearity solidification, dilute binary alloy, dynamic control

EFFECT OF BIAS STRESS ON NON-LINEAR INTERNAL FRICTION OF Al-Mg ALLOY

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Acta Metallurgica Sinica(English Letters) 1992年第3期5卷 166-171页

作者： TAN Qi University of science and technology of China,Hefei,China Univ of science and technology of China Hefei China

The influence of longitudinal and torsional bias stresses on anomalous amplitude-dependent internal friction was *** longitudinal bias stress may always weaken the anomalous amplitude-dependent effect,while the torsional one may induce different effects from differ- ent directions *** stress effect exhibits only in properly heat treated and cold worked ahoy *** anomalous amplitude-dependent internal friction peaks,P_3,P_2 and P_1, are found to be related closely to slant dislocation kink ***,the application of bias stress to internal friction would be contributed to the study on dislocation structure.

关键词： internal friction bias stress anomalous amplitude effect dislocation kink

Redistribution of Boron during Ferrite Reaction in Nb-B Microalloyed Steel

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International Journal of Minerals,Metallurgy and Materials 1998年第4期12卷 223-227页

作者： Shanwu Yang Xinlai He(Applied science School, University of science and technology Beijing, Beijing 100083, China) Applied science School University of Science and Technology Beijing Beijing 100083 China

By contrast of microstructure and boron distribution in the same area of samples, the behavior of boronduring ferrite reaction in Nb-B microalloyed steel was studied. Boron atoms have segregated to original austeniteboundaries betfore ferrite reaction starts during isothermal treatment. The concentration of boron in small Pieces offerrite foming along austenite boundaries may be remarkably higher than that in austenite matrix, but it will reducegradually when the ferrite continuously grows. There is no obvious boron segregation on interface of γ/α and α/α.These facts indicate that ferrite growth is not controlled by diffusion of boron in austenite.

关键词： boron segregation ferrite reaction microalloyed steel

A quasi-human algorithm for solving the three-dimensional rectangular packing problem

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science China(Information sciences) 2010年第12期53卷 2389-2398页

作者： HE Kun & HUANG WenQi School of Computer science and technology, Huazhong University of science and technology, Wuhan 430074, China School of Computer science and technology Huazhong University of Science and Technology

Based on the concept of maximal rectangular space that can be filled at current time and the siege warfare tactics, we make several critical improvements on the quasi-human caving-degree approach to get a stronger algorithm ICDA for a classical NP hard problem: the three-dimensional rectangular packing problem. Within similar computing time, the new algorithm gained an average volume utilization of 90.92% on the natural and difficult 100 benchmarks, called BR15, where items to be packed are almost different in size. Compared with current best record just reported in the literature in 2010, our result makes an improvement by 0.54%.

关键词： NP hard three-dimensional packing quasi-human action space caving degree