The Internal Oxidation of Ternary Alloys. VI: The Transition from Internal to External Oxidation of the Most-Reactive Component under Intermediate Oxidant Pressures

The conditions for the transition from internal to external oxidation of the most-reactive component C of ternary A–B–C alloys are examined, assuming the presence of external scales of the oxide of the component of intermediate reactivity B. For this, approximate expressions for the diffusion coefficient of oxygen and for the concentration of oxygen dissolved in the binary A–B alloy matrix within the zone of internal oxidation as functions of the composition of the metal matrix within the zone of internal oxidation are used. Numerical calculations of the critical content of C needed for this transition are carried out for different combinations of values of the various parameters involved. The results obtained for the ternary alloys are compared with the corresponding data calculated for the binary A–C and B–C alloys under oxygen pressures insufficient to oxidize the most-noble alloy component. This allows to predict the possibility of existence of a third-element effect under intermediate oxidant pressures.     

Fe—Cr—Ni—Mo—C阀座材料的时效硬化及时效过程中的相转变

Fe-18.2Cr-6.9Ni-2.5Mo-1.5C材料铸态组成相为奥氏体和M7C_3型碳化物,在随后加热时可产生时效硬化现象,最佳时效温度为650℃。时效过程中可产生α-铁索体和M_23C_6型碳化物两个新相。     

金刚石修整滚轮CAD/CAPP集成技术研究

金刚石修整滚轮是目前最为有效的高效、高精砂轮成形修整工具，迎合了磨削技术高精、高速和高效发展趋势，内电镀高精度修整滚轮制造工艺复杂、工序多，影响制造精度因素较多，修整参数选择、滚轮图纸设计和工艺编制是生产中的关键环节。本文从分析金刚石修整滚轮设计制造的特点人手，应用CAD／CAPP集成技术实现了金刚石修整滚轮设计、工艺规程编制和技术文件管理的自动化，提高了滚轮制造工艺水平和对产品质量的控制能力，较好地解决了一些设计和工艺过程相对简单、变化较小的定型产品的CAD／CAPP集成化的问题。     

用胶粘代替点焊工艺

采用点焊工艺生产拖拉机机罩，点焊压痕影响了外观质量，通过对几种方案的探讨和大量的胶粘试验，确定了一种用结构胶粘结代替点焊的工艺，该工艺使制件的外观质量得以大幅度提高，而生产成本则明显降低。     

酚酞示波极谱及其在痕量钌催化分析中的应用

在稀盐酸介质中酚酞于－０．５５Ｖ处产生一灵敏的单扫描示波极谱波。基于在稀盐酸介质中及１００℃下，痕量Ｒｕ（Ⅲ）对高碘酸盐氧化酚酞这一缓慢反应的强烈催化作用，用自来水冷却中止反应，采用单扫描示波极谱波研究Ｒｕ这一新的指示反应，建立检出限和测定范围分别为０．０５ｎｇ／ｍｌＲｕ的催化反应－示波极谱分析新方法，并用于实际试样分析，结果较好。     

基于B/S架构的嵌入式网络视频监控系统

根据目前视频监控需求,采用ARM11处理器与Linux操作系统相结合的方式,提出了一种基于B/S架构的远程网络视频监控方案。使用V4L2进行视频图像采集,选择H.264压缩标准,通过硬件多格式编码器MFC完成视频硬件压缩。运用RTP流媒体传输技术实现视频数据的打包传输,客户端通过安装Active X控件完成视频图像的显示,最终实现网络视频监控功能。     

PCET based copy-move forgery detection in images under geometric transforms

With the advent of the powerful editing software and sophisticated digital cameras, it is now possible to manipulate images. Copy-move is one of the most common methods for image manipulation. Several methods have been proposed to detect and locate the tampered regions, while many methods failed when the copied region undergone some geometric transformations before being pasted, because of the de-synchronization in the searching procedure. This paper presents an efficient technique for detecting the copy-move forgery under geometric transforms. Firstly, the forged image is divided into overlapping circular blocks, and Polar Complex Exponential Transform (PCET) is employed to each block to extract the invariant features, thus, the PCET kernels represent each block. Secondly, the Approximate Nearest Neighbor (ANN) Searching Problem is used for identifying the potential similar blocks by means of locality sensitive hashing (LSH). In order to make the algorithm more robust, morphological operations are applied to remove the wrong similar blocks. Experimental results show that our proposed technique is robust to geometric transformations with low computational complexity.     

Study on the security of the authentication scheme with key recycling in QKD

In quantum key distribution (QKD), the information theoretically secure authentication is necessary to guarantee the integrity and authenticity of the exchanged information over the classical channel. In order to reduce the key consumption, the authentication scheme with key recycling (KR), in which a secret but fixed hash function is used for multiple messages while each tag is encrypted with a one-time pad (OTP), is preferred in QKD. Based on the assumption that the OTP key is perfect, the security of the authentication scheme has be proved. However, the OTP key of authentication in a practical QKD system is not perfect. How the imperfect OTP affects the security of authentication scheme with KR is analyzed thoroughly in this paper. In a practical QKD, the information of the OTP key resulting from QKD is partially leaked to the adversary. Although the information leakage is usually so little to be neglected, it will lead to the increasing degraded security of the authentication scheme as the system runs continuously. Both our theoretical analysis and simulation results demonstrate that the security level of authentication scheme with KR, mainly indicated by its substitution probability, degrades exponentially in the number of rounds and gradually diminishes to zero.     

Recover Fault Services via Complex Service-to-Node Mappings in Wireless Sensor Networks

With the motivation of seamlessly extending wireless sensor networks to the external environment, service-oriented architecture comes up as a promising solution. However, as sensor nodes are failure prone, this consequently renders the whole wireless sensor network to seriously faulty. When a particular node is faulty, the service on it should be migrated into those substitute sensor nodes that are in a normal status. Currently, two kinds of approaches exist to identify the substitute sensor nodes: the most common approach is to prepare redundancy nodes, though the involved tasks such as maintaining redundancy nodes, i.e., relocating the new node, lead to an extra burden on the wireless sensor networks. More recently, other approaches without using redundancy nodes are emerging, and they merely select the substitute nodes in a sensor node’s perspective i.e., migrating the service of faulty node to it’s nearest sensor node, though usually neglecting the requirements of the application level. Even a few work consider the need of the application level, they perform at packets granularity and don’t fit well at service granularity. In this paper, we aim to remove these limitations in the wireless sensor network with the service-oriented architecture. Instead of deploying redundancy nodes, the proposed mechanism replaces the faulty sensor node with consideration of the similarity on the application level, as well as on the sensor level. On the application level, we apply the Bloom Filter for its high efficiency and low space costs. While on the sensor level, we design an objective solution via the coefficient of a variation as an evaluation for choosing the substitute on the sensor level.     

基于μC/OS-Ⅱ的数据采集模块设计

针对车载装备上传感器数据采集模块的体积小、可靠性高、实时性好等需求,设计了基于嵌入式实时操作系统μC/OS-Ⅱ的数据采集模块,选用集成了ADC与CAN通信功能等多种外设的Cortex-M3内核芯片STM32F107VCT6,移植嵌入式操作系统以简化软件设计,提高实时性和可靠性;数据采集模块将采集到的数据通过CAN总线实时地发送到主控计算机,同时也通过FatFs文件系统存储在SD卡中,便于计算机读取其中数据,进行离线分析;电路优化设计和数字滤波算法,提高了数据采集模块抗干扰能力和采样精度;通过实验验证,该数据采集模块可以准确、及时地获取和发送传感器数据,具有较高的可靠性和实时性.