Effects of a radial electric field on the thinning of a slightly viscoelastic liquid jet

In this work, we study numerically the thinning of a perfectly conducting, slightly viscoelastic liquid jet under a radial electric field by using a one-dimensional model. In the presence of the electric field, the viscoelastic jet develops into a stable beads-on-a-string structure with a uniform thickness filament as in the non-electrified case, but the \( 1/3De \) (De: the Deborah number) exponential law of filament thinning and polymer stress growth holds no more. The electric field decelerates the thinning of the jet and induces periodic oscillations of the flow properties. The balance between the surface tension, viscoelastic stress and electrostatic force is absent in the filament, and as a result, the extensional flow there becomes unsteady.     

Optimized design of sandwich panels for integral thermal protection systems

This paper proposes a new ITPS panel with special corrugated-core webs which are designed with cutouts for weight saving. The structural design problem was formulated with mass per unit area of the ITPS as the objective function and some functional requirements as constraints. We developed the optimizer fulfilling both thermal and structural functions for minimal areal density. The optimization problem was solved by interpolating the residual error of response surface approximation (RSA) with Radial Basis Function (RBF) to establish the improved RSA (IRSA). The 400 preliminary design points were obtained using Latin Hypercube Sampling method. The quadratic polynomial RSA of the ITPS sandwich panel performance was generated by the least squares method (LSM) based on finite element results and IRSA was used to optimize the constraints. Transient heat transfer, stress and buckling analyses were conducted using finite element method (FEM). Finally, a new ITPS panel with optimal dimensions was obtained. The optimization results show that the areal density of the new ITPS panel decreases by 26.27 % compared with the previous research, which proves the potential of this new design optimization method for the future spacecraft vehicles.     

On design optimization for structural crashworthiness and its state of the art

Optimization for structural crashworthiness and energy absorption has become an important topic of research attributable to its proven benefits to public safety and social economy. This paper provides a comprehensive review of the important studies on design optimization for structural crashworthiness and energy absorption. First, the design criteria used in crashworthiness and energy absorption are reviewed and the surrogate modeling to evaluate these criteria is discussed. Second, multiobjective optimization, optimization under uncertainties and topology optimization are reviewed from concepts, algorithms to applications in relation to crashworthiness. Third, the crashworthy structures are summarized, from generically novel structural configurations to industrial applications. Finally, some conclusions and recommendations are provided to enable academia and industry to become more aware of the available capabilities and recent developments in design optimization for structural crashworthiness and energy absorption.

     

Multi-objective and multi-case reliability-based design optimization for tailor rolled blank (TRB) structures

Structural and Multidisciplinary Optimization - Light weight and crashworthiness signify two main challenges facing in vehicle industry, which often conflict with each other. In order to achieve...     

偏瘫患者辅助下肢外骨骼设计与仿真分析

针对偏瘫患者外骨骼康复机器人降低外骨骼质量的要求,设计了一种辅助下肢外骨骼机器人,采用柔索驱动的膝关节,具有结构简单,质量轻的特点。同时利用ADAMS建立了外骨骼关节柔索驱动的动力学模型,绳索模块建立了柔索驱动模型,通过Ariel生物运动分析软件,采集髋、膝、踝关节运动数据,运用Spline函数进行了仿真分析。经过仿真分析柔索驱动在上台阶运动过程中的不同拉簧预紧力和拉簧刚度下传动特性和驱动力矩,为进一步研究设计下肢外骨骼提供依据。     

支持向量机决策树在隐患预警模型中的应用

危化企业的安全监控数据具有社会价值,对安全隐患进行实时精确的预测是预警研究的热点,本文从人、设备、环境和管理四个维度出发,对安全生产隐患预警的相关指标进行分析,构建隐患预警指标体系,在此基础上,构建了自底向上的基于支持向量机的决策树多分类预警模型,实现对安全等级的的准确分类并用于预警未来的安全生产状态,通过与自顶向下的多分类模型比较,证实本文所采用的预警模型具有较好的实时性和精确度,满足对预警模型的基本要求.     

无线医疗传感网数据安全与隐私保护问题研究

本文对无线医疗传感网的数据安全与隐私保护进行了综述,描述了无线医疗传感网的网络结构,着重分析了它的特性及安全需求,并详细讨论了无线医疗传感网所面临的网络攻击.从无线医疗传感网的机密性、访问控制、身份认证、隐私保护等安全需求方面进行了相应的研究,最后指出了对无线医疗传感网安全与隐私可能的未来研究方向.     

Distributed adaptive control for vehicular platoon with unknown dead‐zone inputs and velocity/acceleration disturbances

This paper is focused on designing a distributed adaptive control scheme for a vehicular platoon with unknown bounded velocity/acceleration disturbances and unknown nonlinear dead‐zone inputs. Our aim is to design distributed adaptive controllers based on integral sliding mode control techniques that guarantee practical exponential convergence (i.e., exponential stability of an arbitrarily small neighborhood of zero) of the spacing errors and the string stability of the whole vehicular platoon. The contributions of this paper are that: (i) based on a modified constant time headway policy, the whole vehicular platoon is guaranteed to have string stability despite dead zone inputs; (ii) adaptive compensation terms are constructed to compensate for the time‐variant effects caused by unknown bounded velocity/acceleration disturbances, and unknown dead zone inputs; (iii) an efficient numerical method for avoiding the singularity problem of the control law is also proposed. Numerical simulation results show the validity and advantages of the proposed method are significantly higher traffic density and string stability. Copyright © 2016 John Wiley & Sons, Ltd.     

模拟复杂网络下子网络节点抗攻击设计

针对复杂网络节点受攻击而出现的安全性问题,提出在模拟复杂网络基础上结合Feistel算法的子网络节点抵抗攻击方法;该方法通过子网络节点定位参数集,建立恶意节点位置模型,并确定定位真实精度;而后利用Feistel算法对节点密文进行加密处理,进而使加密信息恢复成明文信息,完成模拟复杂网络下子网络节点的抗攻击方法改进;结果证明,该方法不仅能够准确地对恶意节点进行定位,而且增强了节点抗攻击性能,提升了网络安全性。     

教研活动在高校教学中的作用

教研室作为教学活动中最小的独立单位,应该团结和带领教师搞好各项工作.在专业课程,教学与科研活动中发挥重要作用.只有从根本意识上重视了教研室活动的重要性才能加强管理,团结一致,发挥教研室各位教师的主观能动性,才能取得各项工作的成绩.使教研室在高校中才能发挥高效的作用.