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EFFECT OF NITROGEN ON GRAPHITE MORPHOLOGY IN GRAY CAST IRON

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Acta Metallurgica Sinica(English Letters) 1993年第8期6卷 151-155页

作者： ZHAI Qijie HU Hanqi university of Science and technology beijing,beijing,China Faculty of Foundry,university of Science and technology beijing,beijing 100083.China beijing Univ of Science and Technology Beijing China

The distribution of N and morphology of graphite in gray cast iron containing N were studicd by adopting the man-made specimens of Fe-C-Si-Mn alloys with some N added. The N adsorbed along the interfaces between graphite and matrix together with solid- solutioned in graphite is believed to be the principal cause of morpholongical variation of graphite.

关键词： gray cast iron graphite morphology N

Threshold quantum secure direct communication without entanglement

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Science China(Physics,Mechanics & Astronomy) 2008年第2期51卷 176-183页

作者： YANG YuGuang1,3.& WEN QiaoYan2 1 College of Computer Science and technology, beijing university of technology, beijing 100022, China 2 School of Science, beijing university of Posts and Telecommunications, beijing 100876, China 3.State Key Laboratory of Information Security (Graduate School of Chinese Academy of Sciences), beijing 100049, China 1. College of Computer Science and technology Beijing University of Technology Beijing 100022 China 3. State Key Laboratory of Information Security (Graduate School of Chinese Academy of Sciences) Beijing 100049 China 2. School of Science Beijing University of Posts and Telecommunications Beijing 100876 China

For the first time, a threshold quantum secure direct communication (TQSDC) scheme is presented. Similar to the classical Shamir's secret sharing scheme, the sender makes n shares, S1, …, Sn of secret key K and each receiver keeps a share secretly. If the sender wants to send a secret message M to the receivers, he en-codes the information of K and M on a single photon sequence and sends it to one of the receivers. According to the secret shares, the t receivers sequentially per-form the corresponding unitary operations on the single photon sequence and ob-tain the secret message M. The shared shares may be reusable if it can be judged that there is no eavesdropper in line. We discuss that our protocol is feasible with current technology.

关键词： quantum secure direct communication threshold secure direct communication quantum secret sharing

The regular representation and regular covariant representation of crossed products of Woronowicz C^(*)-algebras

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Science China Mathematics 2005年第9期48卷 1245-1259页

作者： ZHANG Xiaoxia~(1,2) & GUO Maozheng~(1,3. 1. School of Mathematical Sciences,Peking university,beijing 100871,China 2. Department of Mathematics,Yantai university,Yantai 264005,China 3. LMAM,Peking university,beijing 100871,China 1. School of Mathematical Sciences Peking University 100871 Beijing China 2. Department of Mathematics Yantai University 264005 Yantai China 3. LMAM Peking University 100871 Beijing China

In this paper,it is shown that the regular representation and regular covariant representation of the crossed products A×α G correspond to the twisted multiplicative unitary operators,where A is a Woronowicz C~*-algebra acted upon by a discrete group ***,it is also shown that the regular covariant C~*-algebra is the Woronowicz C~*-algebra which corresponds to a multiplicative ***,an explicit description of the multiplicative unitary operator for C(SU_q(2) )×α (?) is given in terms of those of the Woronowicz C~*-algebra C(SU_q(2) ) and the discrete group G.

关键词： multiplicative unitary operator, Woronowicz C*-algebra, crossed product.

Theorems for Testing Local Activity of CNN and Application to Cardiac Purkinje Equations

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International Journal of Minerals,Metallurgy and Materials 2000年第2期14卷 139-146页

作者： 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

The theorems for testing the local in one-port cellular neural/inear network (CNN) cells with four local state variables are presented. Using the theorems computes the bifurcation diagrams of the cardiac Purkinje fiber (CPE) equations Which describethe long-lasting action and pace-maker potentials of the Purkinje fiber of the heart. The computer simulation shows that periodic trajectories or convergent trajectories of the CPF Equations can be foun if the cormsponing cell Parameters are located in a positive domainbut nearby edge of chaos. In particular a heart with approximate normal frequency of heartbeat but non-normal electrocardiogram maysuddenly stop by slightly perturbing the parameters of the corresponding CPF Equations when the Paramders are located nearby the edge of chaos in the bifurcation diagrams. This research seems to interpret reasonbly the phenomena that patients with cardiac diseases might suddenly die without warning.

关键词： cellular neural network local activity cardiac Purkinje fiber heartbeat

Calculating Model of Mass Action Concentrations for Mn-C Melts and Optimization of Thermodynamic Parameters

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International Journal of Minerals,Metallurgy and Materials 1998年第4期12卷 208-211页

作者： Jian Zhang(Metallurgy School, university of Science and technology beijing, beijing 100083. China) Metallurgy School University of Science and Technology Beijing Beijing 100083 China

Based on the phase diagram, the coexistence theory of the metallic melt structure involving compoundformation and the regularity of melts containing saturated phase, a calculating model of mass action concentrationsfor Mn-C melts was formulated. According to the activities (or activity coefficients AM. and γc.), obtained by theUnified Interaction Parameter Model (UIPM), the thermodynamic parameters G and G at higher temperatures (1628～1873.K) were optimized by the repeated try and error method. It is testified that G G(873.1273.K) and G (298～1623.K), obtained at lower temperatures, can also be used at the above-mentionedhigher temperatures. The calculated N. and N agree well with ac. and ac obtained by UIPM. This result showsthat the deduced model can reflect the structural reality of Mn-C melts.

关键词： Mn-C melts activity coexistence theory mass action concentration

Calculating Models of Mass Action Concentrations for Fe-P and Cr-P Melts and Optimization of Their Thermodynamic Parameters

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International Journal of Minerals,Metallurgy and Materials 1999年第3期13卷 174-177页

作者： Jian Zhang(Metallurgy School, university of Science and technology beijing, beijing 100083. China) Metallurgy School University of Science and Technology Beijing Beijing 100083 China

Based on the phase diagrams, reliable reference experimental data and the coexistence theory of metallic melts structure involving compound formation, calculating models of mass action concentrations for Fe-P and Cr-P melts have been formulated. At the same time, some of their thermodynamic parameters have been optimized. The calculated results not only agree well with the measuredvalues, but also obey the mass action law rigorously, this in turn shows that these models can reflect the structural characteristics of corresponding melts.

关键词： activity phase diagram coexistence theory mass action concentration

Calculating Models of Mass Action Concentrations for Ni-Mn and Co-Mn Melts and Optimization of Their Thermodynamic Parameters

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International Journal of Minerals,Metallurgy and Materials 2000年第4期14卷 246-250页

作者： Jian Zhang (Metallurgy School, university of Science and technology beijing, beijing 100083. China) Metallurgy School University of Science and Technology Beijing Beijing 100083 China

According to phase diagrams, measured activities as well as the coexistence theory of motallic melts structure involving compound formation, the calculating models of mass action concentrations for Ni-Mn and Co-Mn melts are formulated and their thermodynamic parameters are optimized. As a result, the calculated mass action concentrations agree well with the corresponding measured activities, showing that these models can reflect the structural characteristics of both Ni-Mn and Co-Mn melts.

关键词： activity metallic melts coexistence theory mass action concentration

TEM OBSERVATION OF LOCAL DEFORMATION BAND AT CRACK TIP

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Acta Metallurgica Sinica(English Letters) 1992年第3期5卷 147-153页

作者： YAO Kefu university of Science and technology beijing,beijing,ChinaTANG Naivong CHEN Nanping Tsinghua university,beijing,China beijing Univ of Science and Technology Beijing China

The thin foil specimen of a ferrite-austenite duplex stainless steel was tensiled under transmis- sion electron microscope(TEM).It was found that both in ferrite and austenite the local deformation band at crack tip was formed near to the crack propagating *** forma- tion was related with the crack tip Schmid factor,dislocation shielding,latent hardening and hardening *** the crack tip emitted dislocations to a slip system by the action of pure mode Ⅱ stress resolute,and the decreasing rate of hardening coefficient was suitable,lo- cal deformation band was easy to form.

关键词： crack tip local deformation band dislocation shielding

MECHANISM FOR DIFFUSION OF BORON IN γ-Fe

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Acta Metallurgica Sinica(English Letters) 1992年第5期5卷 318-323页

作者： YU Zongsen CHEN Ning university of Science and technology beijing,beijing,China beijing Univ of Science and Technology Beijing China

Mechanism for diffusion of B in γ-Fe is believed to be mainly by means of boron-vacancy complexes other than as interstitial atoms *** was made of calculation on the ba- sis of theoretical model proposed by the *** calculated diffusion coefficient of B in γ-Fe after this mechanism is consistent with the experimental *** addition,this is also supported by the non-equilibrium segregation phenomenon of B at grain boundaries of γ-Fe and the lattice constant measurement of Fe-B alloy.

关键词： boron vacancy diffusion non-equilibrium segregation γ-Fe