检索结果-南通市图书馆

ATOMIC STATES AND BRITTLENESS OF hcp Ti_3Al-ORDERED-TYPE ALLOYS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 270-276页

作者： h.j. Peng Y.Q. Xie College of Chemistry and Chemical Engineering Central South University Changsha 410083 China College of Materials Science and Engineering Central South University Changsha 410083 China

On the basis of the framework of systematic science of alloys （SSA）, the basic information such as states, volumes, and potential energies of characteristic atoms in hcp Ti-Al system have been determined. The average atomic state of the hcp Ti3Al compound consisting of ψ4^Ti and ψ0^Al atoms is 0.75[Ar] （3dn）^0.573 （3dc）^2.1685 （4sc）^0.972 （4sf）^0.3093 ＋ 0.25[Ne] （3sc）^1.32 （3pc）^1.19 （3sf ＋ 3pf）^0.49. The brittleness of the ordered hcp Ti3Al compound has been discussed considering the fundamental factors, which are atomic states, bond networks, potential energy wave planes, and the ratio xTi/xAl. The existence of more pc and more dc directional electrons in the hcp Ti3Al compound lead to considerable brittleness; From bond networks and potential energy wave planes, the hcp Ti3Al compound has poorer ductility than the pure hcp Ti metal and the pure fcc Al metal; The Al-rich hcp Ti3Al ordered type alloys have poorer ductility than the Ti-rich hcp Ti3Al ordered type alloys.

关键词： Ti3Al alloy atomic state brittleness

Cyclic behavior of reinforced sand under principal stress rotation

在线全文

学校读者我要写书评

暂无评论

journal of Rock Mechanics and Geotechnical Engineering 2017年第4期9卷 585-598页

作者： Alaa h.j. Al-rkaby A. Chegenizadeh h.R. Nikraz Department of Civil Engineering School of Civil and Mechanical Engineering Curtin University Perth Australia

Although the cyclic rotation of the principal stress direction is important,its effect on the deformation behavior and dynamic properties of the reinforced soil has not been reported to *** carried out on large-scale hollow cylinder samples reveal that the cyclic rotation of the principal stress direction results in significant variations of strain components(ε,ε,εand γ) with periodic characteristics despite the deviatoric stress being constant during *** oscillation can be related to the corresponding variations in the stress components and the anisotropic fabric that rotate continuously along the principal stress *** under rotation appears to develop a plastic *** trends are observed for reinforced sand,but the shear interaction,the interlocking between particles and reinforcement layer,and the confinement result in significant reductions in the induced strains and associated irrecoverable plastic *** of the strains occur in the first cycle,and as the number of cycles increases,the presence of strains becomes very small,which is almost *** indicates that the soil has reached anisotropic critical state(ACS),where a stable structure is formed after continuous orientation,realignment and rearrangement of the particles accompanied with increasing cyclic *** in the range of 60°-135° produces more induced strains even in the presence of the reinforcement,when compared with other *** relates to the extension mode of the test in this range in which σ>σand to the relative approach between the mobilized plane and the weakest horizontal *** results in an increase in shear modulus while it appears to have no effect on the damping *** cycles of rotation result in an increase in shear modulus and lower damping ratio due to the densification that causes a decrease in shear strain and less dissipation of energy.

关键词： Cyclic rotation Principal stress direction Reinforced sand Strain components Damping ratio Shear modulus

Oximes： Unrecognized Chameleons in Genera and Specialized Plant Metabolism

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2018年第1期11卷 95-117页

作者： Mette S rensen Elizabeth h.j. Neilson Birger Lindberg Moiler Plant Biochemistry Laboratory Department of Plant and Environmental Sciences University of Copenhagen Thorvaldsensvej 40 Frederiksberg C Copenhagen Denmark VILLUM Center for Plant Plasticity University of Copenhagen Thorvaldsensvej 40 Frederiksberg C Copenhagen Denmark Center for Synthetic Biology University of Copenhagen Thorvaldsensvej 40 Frederiksberg C Copenhagen Denmark

Oximes （R1R2C=NOh） are nitrogen-containing chemical constituents that are formed in species representing all kingdoms of life. In plants, oximes are positioned at important metabolic bifurcation points between general and specialized metabolism. The majority of plant oximes are amino acid-derived metabolites formed by the action of a cytochrome P450 from the CYP79 family. Auxin, cyanogenic glucosides, glucosinolates, and a number of other bioactive specialized metabolites including volatiles are produced from oximes. Oximes with the E configuration have high biological activity compared with Z-oximes. Oximes or their derivatives have been demonstrated or proposed to play roles in growth regulation, plant defense, pollinator attraction, and plant communication with the surrounding environment. In addition, oxime-derived products may serve as quenchers of reactive oxygen species and storage compounds for reduced nitrogen that may be released on demand by the activation of endogenous turnover pathways. As highly bioactive molecules, chemically synthesized oximes have found versatile uses in many sectors of society, especially in the agro- and medical sectors. This review provides an update on the structural diversity, occurrence, and biosynthesis of oximes in plants and discusses their role as key players in plant general and specialized metabolism.

关键词： structural diversity CYP79 auxin cyanogenic glucosides volatile organic compounds E-oxime Z-oxime

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2007年第1期20卷 27-34页

作者： X.B. Li Y.Q. Xie Y.Z. Nie h.j. Peng h.j. Tao F.X. Yu College of Materials Science and Engineering Central South University Changsha 410083 China

On the basis of energy and shape method for the determination of the valence bond （ VB ） structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is ec^29907. （sc^0.4980 ＋ dc^2.4927） ef^1.0098 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.

关键词： valence bond structure temperature titanium

ThE SEEPAGE ChARACTERISTICS OF hETEROGENEOUS BODY WITh DIFFERENT SPREADING SOLUTION MODES AND ITS APPLICATIONS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2007年第5期20卷 363-372页

作者： h.j. Wang A.X. Wu X.S. Chen j. Zhang Civil ＆ Environment Engineering School University of Science and Technology Beijing Beijing 100083 China School of Resources and Safety Engineering Central South University Changsha 410083 China

As the dump was a typically heterogeneous body, the seepage was different with varied spreading solution modes. The phenomenon of lamination that occured in the site was simulated using three layers in an indoor experiment, and the seepage effect comparison experiment of the inside spreading solution model and the top spreading solution model have been carried out. In the inside spreading solution mode, the phreatic planar flew without infiltration and the parallel layer motion model was used to calculate the seepage coefficient and equivalent seepage coefficient of each state respectively. In the top spreading solution model, the phreatic planar flew with an even infiltration on the surface, and the vertical layer motion model was adopted to calculate the above coefficient. The results showed that the seepage coefficient of the inside model was larger than the top model in the heterogeneous body, The ratio of them was between 1.42 and 3.07. On the basis of these results, the following new technologies were discussed： installing a few small diameter mechanical pore sand piles with every lamination in the using dump; drilling some holes one-off in the unused dump. These two methods could changed the top spreading solution into the inside model, thus the seepage in the dump was improved.

关键词： heterogeneous body top spreading solution inside spreading solution sand pile drawing-injection drill

ON ThE SPLITTINGS FOR RECTANGULAR SYSTEMS

在线全文

学校读者我要写书评

暂无评论

journal of Computational Mathematics 1995年第4期13卷 337-342页

作者： h.j. Tian(Department of Mathematics, Shanghai Normal University, Shanghai, China) ShANGhAI NORMAL UNIV DEPT MATHSHANGHAIPEOPLES R CHINA

Recently, M. hanke and M. Neumann([4]) have derived a necessary and sufficient condition on a splitting of A = U-V, which leads to a fixed point system, such that the iterative sequence converges to the least squares solution of minimum a-norm of the system Ax = b. In this paper, we give a necessary and sufficient condition on the splitting such that the iterative sequence converges to the weighted Moore-Penrose solution of the system Ax = b for every to is an element of C-n and every b is an element of C-m. We also provide a necessary and sufficient condition such that the iterative sequence is convergent for every to x(0) is an element of C-n.

关键词： AR Math ON ThE SPLITTINGS FOR RECTANGULAR SYSTEMS

LOW CYCLE FATIGUE AND CREEP-FATIGUE BEhAVIOR OF A hIGh TEMPERATURE ALLOY ON SMOOTh AND NOTChED SPECIMENS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1999年第1期12卷 40-45页

作者： Shi, h.j. Liu, S.L. he, Y.h. Duan, Z.X. Tsinghua Univ Beijing China

A series of low cycle fatigue and creepfatigue tests on smooth specimens and notched specimens were performed with a high temperature alloy used in the manufacture of aeroengine turbine discs. The cyclic stressstrain behavior and fracture characteristics of the notched specimens were emphatically investigated. A comparison of fatigue behavior between smooth and notched specimens was done and lifetime of notched specimens was evaluated. At the same temperature, the fatiguecreep lives of the smooth specimens are far greater than that of the notched specimens.

关键词： low cycle fatigue creepfatigue stress concentration notch effect

Discussion　on　the　Network　Method　for　Calculating　Radiant　Interchange　Within　an　Enclosure

在线全文

学校读者我要写书评

暂无评论

journal of Thermal Science 1994年第2期3卷 130-135页

作者： h.j. Kang W.Q. Tao(School of Energy and Power Engineering, Xi’an jiaotong University, Xi’an, Shaanxi 710049, China) 1. School of Energy and Power Engineering Xi’an Jiaotong University 710049 Xi’an Shaanxi China

In this paper the △- Y transformation of a linear electric circuit is introduced to simplify the computation of net radiant heat exchange on a surface of an enclosure with three surfaces. The illustration of the transformation is given by solving six problems taken from the textbooks. Some discussion concerning the possibility of extending the transformation method to enclosures with more than three surfaces, and the condition for applying the network method are also presented.

关键词： radiative heat transfer network method enclosure.

LOW TEMPERATURE ThERMODYNAMIC STUDY OF ThE STABLE AND METASTABLE PhASES OF SILVER

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2007年第5期20卷 355-362页

作者： X.B. Li Y.Q. Xie Y.Z. Nie h.j. Peng Research Center of Advanced Materials Xiangtan University Xiangtan 411105 China School of Material Science and Engineering University Changsha 410083 China Central South

The low temperature thermodynamics of the stable phase of silver was assessed by the polynomial model and Debye model from the experimental data available in the literature. By means of the constrained non-linear least squares curve fitting arithmetic, two sets of parameter values were determined. The expression of the thermodynamic functions cp（T） and G（T）-h （298.15K） at 0-298.15K were presented. Only the low temperature thermodynamics of the metastable phase of silver can be extrapolated by the Debye model The expression of the thermodynamic functions cp（T） at 0- 298.15K was presented.

关键词： silver thermodynamic heat capacity SGTE (Scientific Group Thermodata Europe)