板料成形数值模拟的关键技术及难点

本文结合国内外板料成形数值模拟的最新研究动态，从关键算法、屈服函数、本构方程、有限元列式、接触问题、破裂准则、回弹计算、起皱分析八个方面叙述了板料成形有限元计算的关键技术及主要难点。     

大规模定制环境下基于产品结构复杂度的工时定额制定研究

针对大规模定制环境下产品种类多、工时制定困难的特点,为了能够快速且准确获取产品工时,研究了产品结构复杂度与工时之间的关系,提出了一种基于产品结构复杂度的工时估算方法.综合考虑影响产品结构复杂度的各种因素后,针对决策结果的排序向量决定决策者权重,引入灰色关联理论,建立了产品结构复杂度计算模型.基于数据库中的工时信息,运用MATLAB软件进行编程确定产品结构复杂度和工时之间的函数关系.最后,以某企业产品加工工时估算实例,证明了所提出的估算方法的可行性.     

Novel prototyping method for microfluidic devices based on thermoplastic polyurethane microcapillary film

Thermoplastic polyurethane microcapillary film (TPU-MCF), as a novel extruded product, inherently contains an array of circular micron-sized capillaries embedded inside the polymer matrix. With the aid of simple laser cutting and conventional sealing technologies, a rapid prototyping method for microfluidic devices is proposed based on the ready-made microstructure of MCFs. Two functionalized microfluidic devices: serpentine micromixer and multi-droplet generator, are rapidly fabricated to demonstrate the advantages and potential of employing this new method. The whole proof-of-concept fabrication process can be completed in 8–10 min in a simple way; each procedure is repeatable with stable performance control of microfluidic devices; and the material cost can be as low as $0.01 for each device. The TPU-MCF and this novel method are expected to provide a new perspective and alternative in microfluidic community with particular requirements.     

VxWorks平台内核态ARINC653分区实时调度算法设计与实现

集成模块化航空电子架构(integrated modular avionic,IMA)已成为主流航空电子系统;ARINC 653作为航空电子设备IMA架构的标准应用接口,成为研究航空电子软件编程方法的入口;最新研究表明,VxWorks能够为航空电子分区管理提供最优化的平台;然而,基于VxWorks的ARINC 653高效分区调度算法依然是研究的“盲区”;由此,设计了VxWorks内核态分层ARINC 653分区实时调度算法,提高了分区调度效率,为VxWorks内核ARINC 653完整性的研究提供非常有价值的参考;实验数据说明,相较于传统用户态分区管理模型,该调度算法使分区释放开销和分区释放抖动两项指标均显著降低.     

Quasi-Newton-type optimized iterative learning control for discrete linear time invariant systems

In this paper, a quasi-Newton-type optimized iterative learning control (ILC) algorithm is investigated for a class of discrete linear time-invariant systems. The proposed learning algorithm is to update the learning gain matrix by a quasi-Newton-type matrix instead of the inversion of the plant. By means of the mathematical inductive method, the monotone convergence of the proposed algorithm is analyzed, which shows that the tracking error monotonously converges to zero after a finite number of iterations. Compared with the existing optimized ILC algorithms, due to the superlinear convergence of quasi-Newton method, the proposed learning law operates with a faster convergent rate and is robust to the ill-condition of the system model, and thus owns a wide range of applications. Numerical simulations demonstrate the validity and effectiveness.     

校园安防前景——安防行业的下一块绿洲

本文主要介绍了校园安防的发展趋势。     

基于视觉一致性的图像检索

提出一种新的彩色图像分割方法,将图像分割成具有明显视觉一致性的区域,这种一致性能够模拟人观察图像时的视觉感受,例如图像中的一片区域具有相同的颜色、纹理。对这样的一致性区域建立特征描述符,如颜色编码、连通系数、面积比例,其中颜色编码是通过将像素在HSI颜色空间中量化得到,进而为整幅图像建立特征描述;然后将这种特征描述用于图像的检索。实验结果表明,这种方法不仅能够很好地模拟图像所带给人的视觉感受,而且对具有视觉一致性的图像检索效果也有很好的表现。     

Binary-image comparison with local-dissimilarity quantification

In this paper, we present a method for binary image comparison. For binary images, intensity information is poor and shape extraction is often difficult. Therefore binary images have to be compared without using feature extraction. Due to the fact that different scene patterns can be present in the images, we propose a modified Hausdorff distance (HD) locally measured in an adaptive way. The resulting set of measures is richer than a single global measure. The local HD measures result in a local-dissimilarity map (LDMap) including the dissimilarity spatial layout. A classification of the images in function of their similarity is carried out on the LDMaps using a support vector machine. The proposed method is tested on a medieval illustration database and compared with other methods to show its efficiency.     

多处理器环境中基于节能及容错的实时动态调度算法

当前处理器由于较高的能量消耗,导致处理器热量散发的提高及系统可靠性的降低,同时任务实际运行中的错误也降低了系统的可靠性.因此同时满足节能性及容错性已经成为目前计算机领域较为关心的问题.提出的调度算法针对实时多处理器计算环境,以执行时间最短的任务优先调度为基础,结合其他有效技术(共享空闲时间回收及检查点技术),使得实时任务在其截止期内完成的同时,能够动态地降低整个系统的能量消耗及动态容错.针对独立任务集及具有依赖关系的任务集,提出两种算法:STFBA1及STFBA2(shortest task first based algorithm).通过实验与目前所知的有效算法相比,算法具有更好的性能(调度长度及能量消耗)及较低的通信时间复杂度.