液态铝合金表面张力快速检测新方法与装置

表面张力是液态合金的重要物性参数之一,铝合金表面张力与其变质处理效果及充型能力等质量参数密切相关,研究铸造铝合金表面张力快速检测方法及装置,对于开发铝合金熔炼质量炉前实时评价系统具有非常重要的实际意义.介绍了一种液态铝合金表面张力快速测试的新方法和新装置,新方法以固定时间内吹入被测液体的气泡个数以及气泡在生长过程中内部压差变化为信息参数,通过回归公式求解表面张力.基于该方法研制的表面张力新型测试装置由单片机测控单元、探头及其锁紧和升降机构、供气单元等部分构成.采用新装置可在5 s内测得铝合金表面张力,且具有较高的测试精度.     

板料弯曲回弹的有限元模拟影响因素研究

阐述了板料成形数值模拟中回弹问题的研究历史和发展现状,分析了塑性弯曲加工中工件发生弯曲回弹的原因、特点及有限元模拟过程的影响因素,总结了回弹模拟的算法,从成形过程模拟和回弹计算两方面系统分析了影响回弹模拟准确性和收敛性的主要因素及改进方向,讨论了模具设计中回弹的补偿算法 ,并提出了当前控制回弹的基本方法     

Thermodynamic reassessment of the Cd−Zn system

The Cd−Zn system has been thermodynamically reassessed with the CALPHAD method by combining more recent experimental data, in particular the activities of zinc in the liquid phase. A good agreement is obtained between the calculated and experimental thermodynamic parameters as well asphase boundaries.     

基于Event-B和Rodin开展形式化软件工程教学

形式化软件工程是软件工程的重要组成部分。Event-B方法是一种软件形式化开发方法,Rodin是支持Event-B方法的开放工具集。基于Event-B方法和Rodin开展形式化软件工程教学,有益于学生正确理解精化等重要的软件工程概念,理解并掌握开发可信软件的方法,是软件工程教学的重要补充。     

有关C语言教学方法优化的探讨

C语言程序设计是一门重要的课程,却难学难教。教学方法优化十分必要。教学方法优化应从激发学生兴趣入手,采用循序渐进的方式,着重培养学生举一反三的编程能力,引导学生写出高质量的程序,并丰富考核方式。     

基于改进FAHP的电力通信网可靠性评估方法研究

论文阐述了可靠性的一般评估方法,在借鉴TMN管理模型的基础上,对电力通信网可靠性进行了分层,构建了可靠性综合评估指标体系.为减少指标体系权重的主观性,提高评估结果的客观性和可信性,提出了一种改进的FAHP综合可靠性评估方法.该方法基于对数最小二乘法(LLSM)进行模糊权重计算,利用限位系数法来实现评估结果的解模糊过程,实例评估验证了该方法的有效性和可行性.最后对电力通信网可靠性的研究方向给出了建议.     

Tackling the Password Problem: Image- and Gesture-Based Alternatives to Alphanumeric Passwords

Abstract

Alphanumeric passwords remain a ubiquitous means of user authentication, yet they are plagued by a fundamental problem: Secure passwords are difficult to create and remember. This paper suggests that image- or gesture-based passwords might strike a better balance between security and usability. It examines two such systems that are currently in widespread commercial use and examines alternative approaches that may offer insights for future improvements. Finally, it considers the possibility that touch-screen gesture passwords may become a viable biometric measure, which may allow them to provide multi-factor gesture-based authentication.     

Sampling average approximation method for a class of stochastic Nash equilibrium problems

We consider a class of stochastic Nash equilibrium problems (SNEP). Under some mild conditions, we reformulate the SNEP as a stochastic mixed complementarity problem (SMCP). We apply the well-known sample average approximation (SAA) method to solve the SMCP. We further introduce a semismooth Newton method to solve the SAA problems. The comprehensive convergence analysis is given as well. In addition, we demonstrate the proposed approach on a stochastic Nash equilibrium model in the wholesale gas–oil markets.     

Nonsmooth identification of mechanical systems with backlash-like hysteresis

Backlash-like hysteresis is one of the nonsmooth and multi-valued nonlinearities usually existing in mechanical systems. The traditional identification method is quite difficult to be used to model the systems involved with such complex nonlinearities. In this paper, a nonsmooth recursive identification algorithm for the systems with backlash-like hysteresis is proposed. In this method, the concept of Clarke subgradient is introduced to approximate the gradients at nonsmooth points and the so-called bundle method is used to obtain the optimization search direction in nonsmooth cases. Then, a recursive algorithm based on the idea of bundle method is developed for parameter estimation. After that, the convergence analysis of the algorithm is investigated. Finally, simulation results to validate the proposed method on a simulated mechanical transmission system are presented.