集束射流氧枪的设计与应用

利用软件CFX10.0对电炉炼钢氧枪在集束射流和普通射流两种状态下的特征进行了数值模拟.通过结果对比,论证了集束射流氧枪的优越性,并且在安阳一炼轧厂100t竖式电炉使用并对其使用效果进行了分析.结果表明,安阳一炼轧厂电炉使用集束氧枪后,吨钢电耗平均降低了30kW·h,吨钢氧耗和生产成本等方面都有明显的优势.冶炼周期略有增加,主要在于采用的原料中铁水比例增加,导致周期增加.当热装铁水比处于50%左右时,吨钢氧耗、吨钢电耗、冶炼周期和生产成本均变化不大,所以建议铁水比保持在50%.     

Finite Eement Facture Aalysis of the Main Arm of Tower Cranes with the 3-D Cracks

In this paper the local solutions of displacement fields in front of three-dimensional cracks are introduced and a new singular element of three-dimensional crack problems is constructed, and a new method for calculating stress intensity factors of three-dimensional crack problems is presented. With the present method, the structural strength of with longitudinal closed cracks under axial tensions is analyzed. It is possible for the crack to propagate because there are ring tensile stresses near joints of the main arm in tower cranes under axial press stresses. The stress and the stress intensity factor are calculated at joints on the main arm of tower cranes. Influences of welding residual stress on stress intensity factors and stresses are discussed.     

Existence of invariant curves for a Fermi-type impact absorber

In this paper we study an impact absorber which is similar to the Fermi accelerator and can be described as a ball moves in a periodically oscillating ring with a wall and reflects elastically from the wall. First, Poincaré map of the system is established. The existence of invariant curves for the map is proved based on Moser’s twist theorem. Accordingly, the velocities of the ball are always bounded for any initial motion for all time. Moreover, the symmetry of the Poincaré map is discussed. Finally, some numerical simulations are given to demonstrate the theoretical results.

     

Three Attacks on the Mediated Semi-Quantum Key Distribution without Invoking Quantum Measurement

Semi-quantum key distribution is a very interesting new branch of quantum key distribution. It can be implemented when one or more participants are restricted to operate quantum states only on the quantum computational basis. Very recently, a mediated semi-quantum key distribution protocol without invoking two participants' quantum measurement has been proposed. The protocol allows two “classical” participants without sophisticated quantum capability to establish a shared secret key under an untrusted third party. It is claimed that the protocol is secure against several well-known attacks. However, in this paper, it is first pointed out that there exist three attacks “Measurement Attack, Modification Attack, and Collective Attack” on the mediated semi-quantum key distribution protocol without invoking quantum measurement. By proposed attacks, a malicious third party can obtain the secret key without being noticed by legitimated participants.     

采用瓣叶复合材料的生物心脏瓣膜的力学分析

采用微观组织结构分析及宏观复合材料分析结合的方法,分析了猪主动脉瓣的非线性复合材料性质,提出了一种适用于猪主动脉瓣的非线性复合材料本构模型,用提出的非线性复合材料本构模型,对闭合承载状态下的等厚度与变厚度几何模型的猪主动脉瓣的应力分布及变形进行了有限元数值模拟,发现：与各向同性瓣叶相比,单向增强复合材料的瓣叶不但具有较强的承载能力,而且具有较大的柔软性。     

The interaction between crack and electric dipole of piezoelectricity

Discrete dipoles located near the crack tip play an important role in nonlinear electric field induced fracture of piezoelectric ceramics. A physico-mathematical model of dipole is constructed of two generalized concentrated piezoelectric forces with equal density and opposite sign. The interaction between crack and electric dipole in piezoelectricity is analyzed. The closed form solutions, including those for stress and electric displacement, crack opening displacement and electric potential, are obtained. The function of piezoelectric anisotropic direction,p _a (θ)=cosθ+p _a sinθ, can be used to express the influence of a dipole's direction. In the case that a dipole locates near crack tip, the piezoelectric stress intensity factor is a power function with −3/2 index of the distance between dipole and crack tip. Supported by National Natural Science Foundation of China(No. 10072033)     

Stress analysis of electrostrictive material with an elliptic defect

It is shown that the constitutive equation and electric body force used to discuss the stress analysis of electrostrictive material in some previous literature are not appropriate. This paper presents the corrected stress solution for the infinite plane with an insulated elliptic hole under an applied electrical field. The numerical result obtained for the PMN material constants show that the stress near the end of the narrow elliptic hole is the tensile stress.     

拉－扭复合加载下不锈钢的弹塑性本构关系——Ⅱ．理论

提出应力是塑性应变空间内蕴几何学参数的泛函．一般情况下，塑性应变空间是非欧几何空间，而其度量张量是塑性应变和其历史的函数，但在初始各向同性和不可压的情况下可取成欧氏空间．本文在Ｉｌｙｕｓｈｉｎ理论，和Ｖａｌａｎｉｓ理论的基础上，提出在拉－扭复合加载下的εｐ１－εｐ３空间中新的积分型弹塑性本构关系，所建理论预测的结果和实验［１］相当一致，表明理论是合理的     

正态和非正态分布下结构系统的可靠性分析

本文在分析现有计算方法的基础上,提出了适合于多种结构系统可靠性分析的五种评价衡准.在失效概率的计算过程中,考虑了多种分布形式及随机变量间、失效形式间的相关性,从而为结构系统的最优可靠性设计提供了可靠的设计依据。