Rigidity and regularity in group actions

Some new results on the rigidity of automorphism groups and the regularity of(?)-Neumann operator in group actions are presented.     

SEISMIC RANDOM RESPONSE ANALYSIS OF HYSTERETIC SYSTEMS WITH PSEUDO EXCITATION METHOD

The stationary random responses of nonlinear shear-type Multi-Degrees-of-Freedom (MDOF) hysteretic system are analyzed by using the Pseudo Excitation Method (PEM) combined with the Equivalent Linearization Method (ELM). The solution of the equivalent linear system is obtained by iteratively solving complex algebraic equations instead of the Lyapunov equations. The efficiency of this method is much higher for practical engineering systems with many degrees-of-freedom. Supported by NNSFC (Project No. 19772009), NKBRSF fund (No. G1999032805) and Doctoral Funding of State Education Ministry (No. 97014120).     

Laws of Influence of Structural Characteristics on the Strength and Crack Resistance of Aging Metallic Materials

The structural characteristics (the volume fraction, size, and shape of and the distance among hardening-phase particles) of aging alloys and steels, which define the behavior of the critical stress intensity factor during thermal hardening, are determined using the structural-mechanical approach we have developed. It is experimentally demonstrated for maraging steels that our approach is capable of proving the correlations of strength, plasticity, and crack- resistance with the structural characteristics, which were varied by changing the chemical composition of steel and thermokinetic aging conditions__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 1, pp. 94–101, January 2005.     

The constitutive equation resemblance of elastic — Plastic multiphase solid

Based on composite materials, the equivalent elastic-plastic constitutive equations of multiphase solid are researched. According to the suggested definition of constitutive equivalence it is demonstrated that the multiphase solid, composed of several kinds of homogeneous elastic-plastic media that conform to the generalized normality rule, has the same type of constitutive equations as its constituents have that also conform to the generalized normality rule.     

求极限的等价无穷大代换

给出等价无穷大代换的法则,并由此得到求某些未定式极限的计算方法.     

S-烷基异硫脲盐作为硫醇替代物经环氧开环反应合成β-羟基硫化物

S-烷基异硫脲盐作为一种无毒、无味、易于制备的硫醇替代物，在碱性水介质中、室温下与多种环氧化合物发生环氧开环反应，区域选择性、高收率地合成了一系列β-羟基硫化物。     

Annealing effect in glass woven fabric composites,Part II. Bending properties

Effects of annealing on bending properties of composites reinforced with plain glass woven fabrics that were treated with different concentrations of silane coupling agent were investigated in this paper. Bending strength increased by annealing in the specimen treated with lower silane concentration. Higher annealing temperature in a range from 80°C to 150°C led to higher bending strength. Then, the fracture mode changed from a micro-crack type (low strength type) to a branched matrix crack type (high strength type) by annealing.     

Design equations for the assessment and FRP-strengthening of reinforced rectangular concrete columns under combined biaxial bending and axial loads

A simple procedure is proposed for the assessment of reinforced rectangular concrete columns under combined biaxial bending and axial loads and for the design of a correct amount of FRP-strengthening for underdesigned concrete sections. Approximate closed-form equations are developed based on the load contour method originally proposed by Bresler for reinforced concrete sections. The 3D failure surface is approximated along its contours, at a constant axial load, by means of equations given as the sum of the acting/resisting moment ratio in the directions of principal axes of the sections, raised to a power depending on the axial load, the steel reinforcement ratio, and the section shape. The method is extended to FRP-strengthened sections. Moreover, to make it possible to apply the load contour method in a more practical way, simple closed-form equations are developed for rectangular reinforced concrete sections with a two-way steel reinforcement and FRP strengthenings on each side. A comparison between the approach proposed and the fiber method (which is considered exact) shows that the simplified equations correctly represent the section interaction diagram. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 44, No. 3, pp. 443–462, May–June, 2008.     

Chromatic Uniqueness of a Family of K_4-Homeomorphs

§ 1.Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ａｌｌｇｒａｐｈｓｃｏｎｓｉｄｅｒｅｄｉｎｔｈｉｓｐａｐｅｒａｒｅｆｉｎｉｔｅ,ｕｎｄｉｒｅｃｔｅｄ ,ｕｎｌｏｏｐｅｄａｎｄｓｉｍｐｌｅｇｒａｐｈｓ.ＷｅｄｅｎｏｔｅｔｈｅｃｈｒｏｍａｔｉｃｐｏｌｙｎｏｍｉａｌｏｆａｇｒａｐｈＧｂｙＰ(Ｇ ,λ)ｏｒＰ(Ｇ) .ＷｅｓａｙｇｒａｐｈｓＧａｎｄＨｔｏｂｅｃｈｒｏｍａｔｉａｌｌｙｅｑｕｉｖａｌｅｎｔｉｆＰ(Ｇ) =Ｐ(Ｈ) .ＴｈｅｃｈｒｏｍａｔｉｃｕｎｉｑｕｅｎｅｓｓｏｆａｇｒａｐｈＧｉｓｅｓｔａｂｌｉｓｈｅｄｉｆｉｔｃａｎｂｅｄｅｄ…