基于混沌遗传算法的铜闪速熔炼过程操作模式智能优化系统

提出了一种铜闪速熔炼操作模式智能优化系统．该系统首先采用动态T-S递归模糊神经网络（Dynamic T-S Recurrent Fuzzy Neural Network, DTRFNN）对工艺参数进行软测量,再采用模式分解的方法对海量数据进行分解,最后对模式子集采用基于神经网络和混沌遗传算法的铜闪速熔炼操作模式智能优化方法进行优化．将该控制系统应用到铜闪速熔炼中,提高了铜闪速炉的生产效率．     

在CFIFLASH设备上实现JFFS2文件系统

本文首先介绍了JFFS2,FLASH和MTD的相关知识。之后详细介绍了如何利用MTD技术在flash上实现JFFs2文件系统。包括驱动程序编写,内核修改和配置,根文件系统的建立。最终使得JFFS2文件系统可以稳定、可靠地运行在ARM920开发板上。同时也指出了JFFS2的局限性和发展趋势。     

Implementation and characterization of flash-based hardware security primitives for cryptographic key generation

Hardware security primitives, also known as physical unclonable functions (PUFs), perform innovative roles to extract the randomness unique to specific hardware. This paper proposes a novel hardware security primitive using a commercial off-the-shelf flash memory chip that is an intrinsic part of most commercial Internet of Things (IoT) devices. First, we define a hardware security source model to describe a hardware-based fixed random bit generator for use in security applications, such as cryptographic key generation. Then, we propose a hardware security primitive with flash memory by exploiting the variability of tunneling electrons in the floating gate. In accordance with the requirements for robustness against the environment, timing variations, and random errors, we developed an adaptive extraction algorithm for the flash PUF. Experimental results show that the proposed flash PUF successfully generates a fixed random response, where the uniqueness is 49.1%, steadiness is 3.8%, uniformity is 50.2%, and min-entropy per bit is 0.87. Thus, our approach can be applied to security applications with reliability and satisfy high-entropy requirements, such as cryptographic key generation for IoT devices.     

Nanocrystalline Nd–Fe–B Anisotropic Magnets by Flash Spark Plasma Sintering

Flash spark plasma sintering (flash SPS) is an attractive method to obtain Nd–Fe–B magnets with anisotropic magnetic properties when starting from melt-spun powders. Compared to the benchmark processing route via hot pressing with subsequent die upsetting, flash SPS promises electroplasticity as an additional deformation mechanism and reduced tool wear, while maximizing magnetic properties by tailoring the microstructure—fully dense and high texture. A detailed parameter study is conducted to understand the influence of Flash SPS parameters on the densification and magnetic properties of commercial MQU-F powder. It is revealed that the presintering conditions and preheating temperature before applying the power pulse play a major role for tailoring grain size and texture in the case of hot deformation via Flash SPS. Detailed microstructure and magnetic domain evaluation disclose the texture enhancement with increasing flash SPS temperature at the expense of coercivity. The best compromise between remanence and coercivity (1.37 T and 1195 kA m⁻¹, respectively) is achieved through a combination of presintering at 500 °C for 120 s and preheating temperature of 600 °C, resulting in a magnet with energy product (BH)_max of 350 kJm⁻³. These findings show the potential of flash SPS to obtain fully dense anisotropic nanocrystalline magnets with high magnetic performance.     

A Perspective on Emerging and Future Sintering Technologies of Ceramic Materials

Novel sintering methods have emerged in the recent past years, which have raised great interest in the scientific community. Relying on electric field effects, high heating rates, the use of mechanical pressure, or hydrothermal conditions, they offer fundamental advantages compared to conventional sintering routes like minimizing the energy consumption and enhancing the process efficiency. This perspective aims at explaining these effects in a general way and presenting the status quo of using them for the processing of high-performing ceramic materials. In detail, this work focuses on flash sintering, ultrafast high-temperature sintering, spark plasma sintering, cold sintering, and photonic sintering methods based on different light sources. The specificities, potentials, and limitations of each method are compared, especially in the light of a possible industrialization.     

2011年8月份十大重要安全漏洞分析

国家计算机网络入侵防范中心在该文中介绍了2011年8月份的网络安全漏洞的整体情况,分别统计了“紧急”、“高”、“中”、“低”不同威胁级别的漏洞数量,并从中选取了十个重要安全漏洞,对其内容和危害进行了分析,进而提出了应对的措施。     

闪光焊机液压伺服系统故障诊断的研究

为了提高闪光焊机液压伺服系统故障诊断的准确性、实时性,在对液压伺服故障机理分析的基础上,运用计算机技术、数字信号处理技术、模糊故障诊断理论,设计出焊机液压故障诊断系统.对液压伺服系统模糊故障诊断算法进行了研究,并将其应用到焊机液压故障诊断系统.实际故障诊断结果表明,故障诊断系统能准确判断出液压伺服系统的故障部位、故障类...     

大容量NAND Flash文件系统中的地址映射算法研究

随着Flash芯片容量的日益增长,如何设计低空间复杂度的Flash管理算法已经成为RAM空间受限的嵌入式存储系统的一个关键问题.本文根据文件在Flash介质上连续存放的特性,引入区段的概念,提出基于极大映射区段的地址映射算法,并使用简单的数据结构和高效的算法来维护映射中的区段,大大减小了Flash文件系统的RAM用量.最后,通过不同应用负载的实验验证了该算法的有效性.在部分应用负载下,可降低高达95%的RAM使用量.     

NAND Flash文件系统的研究与改进

NAND Flash因非易失、抗震、低功耗等特点被广泛应用于嵌入式系统的大容量数据存储中。虽然随着JFFS3文件系统的提出,理论上解决了初始化文件系统时需扫描整个闪存分区、挂载时间过长、占用内存过多的缺陷,但并未解决NAND Flash本身随机读写严重不均衡的问题。在对JFFS3文件系统研究的基础上提出采用FDTree索引结构的SFFS文件系统,以解决在数据频繁更新的环境里NAND Flash数据管理问题,给出了考虑损耗均衡兼顾回收效率的垃圾回收机制。