A novel adaptive steganography based on local complexity and human vision sensitivity

This paper presents a novel adaptive steganographic scheme that is capable of both preventing visual degradation and providing a large embedding capacity. The embedding capacity of each pixel is dynamically determined by the local complexity of the cover image, allowing us to maintain good visual quality as well as embedding a large amount of secret messages. We classify pixels into three levels based on the variance of the local complexity of the cover image. When determining which level of local complexity a pixel should belong to, we take human vision sensitivity into consideration. This ensures that the visual artifacts appeared in the stego image are imperceptible, and the difference between the original and stego image is indistinguishable by the human visual system. The pixel classification assures that the embedding capacity offered by a cover image is bounded by the embedding capacity imposed on three levels that are distinguished by two boundary thresholds values. This allows us to derive a combination ratio of the maximal embedding capacity encountered with at each level. Consequently, our scheme is capable of determining two threshold values according to the desired demand of the embedding capacity requested by the user. Experimental results demonstrated that our adaptive steganographic algorithm produces insignificant visual distortion due to the hidden message. It provides high embedding capacity superior to that offered by a number of existing schemes. Our algorithm can resist the RS steganalysis attack, and it is statistically invisible for the attack of histogram comparison. The proposed scheme is simple, efficient and feasible for adaptive steganographic applications.     

Passive control of uncertain multiple input-delayed systems using reduction method

In order to conveniently analyze stability of uncertain multiple input-delayed closed-loop systems and successfully synthesize passive controllers for a general class of uncertain multiple input-delayed systems with disturbance, the so-called reduction method is applied to the multiple input-delayed systems with parametric uncertainties. A feedback controller associated with the system state and the past control action is designed to guarantee the passivity of the closed-loop systems for all admissible uncertainties. The theoretical findings are illustrated and verified with one numerical example.     

Robust nonlinear power iteration algorithm for adaptive blind separation of independent signals

In this paper, we elaborate an extension of classical power iteration method to nonlinear power iteration for blind separation of multiple independent sources from observed array output signals. The present algorithm, referred to as NPI, considers the estimating of the separating matrix as a nonlinear power iteration problem. By naturally choosing the positive definite normalizer for nonlinear power term, the resulting algorithm not only yields robust convergence behavior but also guarantees the orthonormality of the separating matrix at each iteration. To circumvent the difficulty of solving the inverse square root for the normalizer, an efficient adaptive singular value decomposition (SVD) technique is also adopted to obtain a fast implementation of NPI. The estimation accuracy and convergence speed of the present algorithm are illustrated through simulation results and compared with the existing adaptive algorithms.     

Attribute-based on-demand multicast group setup with membership anonymity

In many applications, it is desired to dynamically establish temporary multicast groups for secure message delivery. It is also often the case that the group membership information itself is sensitive and needs to be well protected. However, existing solutions either fail to address the issue of membership anonymity or do not scale well for dynamically established groups. In this paper, we propose a highly scalable solution for dynamical multicast group setup with group membership anonymity. In the proposed solution, scalability and membership anonymity are achieved via a novel design that integrates techniques such as ciphertext-policy attribute-based encryption (CP-ABE). In our design, multicast groups are specified through group member attributes. As these attributes are potentially able to be shared by unlimited number of group members, our proposed scheme scales well. Also, high level of membership anonymity is guaranteed such that every group member knows nothing but his own group membership only. The complexity of our proposed scheme in terms of computational overhead and ciphertext size is O(n), where n is the number of attributes and independent to the group size.     

基于PSpice的模拟电路故障知识获取新方法

电子装备中的模拟部分由于器件的离散性、容差、非线性等问题导致故障知识获取困难和不全面;针对该问题的主要来源—故障原始数据的收集,提出了利用PSPICE软件与Visual Basic语言相结合,以命令行作为结合点,实现故障知识获取的自动化,该方法的实质是通过计算机用穷举法自动在所有可能故障情况下进行仿真获取故障知识;该方法可以降低知识获取的工作量以及对专家的依赖性,为开发军用电子装备,特别是新装备的实用智能故障诊断系统奠定基础。     

Novel in-line WAT processing of 55 nm CIS product and effect of process waiting time on void growth at interface of SiCN with copper capping layer

The WAT (wafer acceptance test) is the last examination that is performed before a wafer or a chip fab out to ensure the quality and stability of chip performance. In 55 nm CIS (CMOS Image Sensor) technology, a highly smooth wafer surface is critical for the BSI (backside illumination) process. The traditional WAT process cannot be used; rather the in-line WAT must be performed during the process for forming copper interconnect. However, increasing the processing time increases the period of exposure of the copper interconnect to air, which is called the Q-time, affecting the reliability of copper interconnect. Nitrogen-doped silicon carbide (also called NDC or SiCN) has been used to fabricate copper diffusion barrier films. PECVD SiCN dielectric has a promisingly low dielectric constant for use as a copper diffusion barrier. Copper diffusion barrier films comprise one or more layers of silicon carbide. Covering a copper layer with a single thin NDC pre-layer significantly increases the maximum allowable Q-time for wafer probing. However, after the Q-time, a void forms between NDC layer and the NDC pre-layer. This work proposes a new two-step NDC process and the optimization of the thickness of the NDC pre-layer. The process has the advantages of providing a high stability for parametric test and a long allowable Q-time. These advantages are achieved by changing the thickness of the NDC pre-layer. This new approach has been analyzed using TEM and by performing parametric tests, and the feasibility has been confirmed experimentally. No void is formed between the NDC layers and a high test stability is achieved when the thickness of the NDC pre-layer is 120 Å.     

Analyzing execution traces: critical-path analysis and distance analysis

International Journal on Software Tools for Technology Transfer - System designers make trade-offs between metrics of interest such as execution time, functional quality and cost to create a...     

10万吨聚丙烯装置仿真应用与环管反应器的模拟

聚丙烯是当今世界5大通用树脂之一,因其优秀的热塑性能使之在工业生产中的应用逐年增加。因此,生产装置和设计公司对各牌号聚丙烯在生产加工中的指标控制也日趋严格,对其工艺的优化也在不断地探讨和实践。本文以中国石油庆阳石化公司10万吨/年聚丙烯装置为基础,结合Honeywell公司的UniSim Design为基础建模平台建立操作工仿真培训系统(OperatorTraining System)。对Basell公司的Spheripol工艺进行全流程模拟与分析,确定与验证合理的操作参数与控制条件。并且还针对Spheripol的环管反应器进行专门的模拟与讨论,应用Honeywell机理优化差值矩阵模块,并进行适当的改进,通过快速迭代和实时收敛大大减轻了各个硬件节点的计算负荷,运用软硬件相结合的双层法在内层建立稳定的机理模型,在外层建立优化的控制模型。同时在计算结果的基础上分析了反应物与产物在环管反应器中的动态特性,以及主要操作条件的变化对浆液密度、反应温度等重要指标的影响,指出了环管反应器在70℃～80℃范围会出现控制临界点,建立了符合其性能的操作指标和优化目标。为实际反应器的生产操作提供了理论依据,并且对今后探讨DCS与...     

使用Visual C++实现多媒体电子出版物中的矢量电子地图

该文介绍在基于光盘的多媒体电子出版物中实现矢量电子地图的关键技术。使用VisualC＋＋和面向对象的方法实现了一个矢量电子地图引擎。     

Thermal comfort and sensation in men wearing a cooling system controlled by skin temperature

OBJECTIVE: The study was done to determine whether thermal comfort (TC), thermal sensation (TS), and subjective factors gauging environmental stress were negatively affected with different cooling methods in men exercising in chemical protective clothing. BACKGROUND: Previous studies have reported that intermittent regional cooling improved the efficacy of cooling as compared with constant cooling (CC), but no studies have addressed whether there is any improvement in thermal comfort. METHODS: Eight male volunteers exercised at moderate work intensity (425 W) in three microclimate cooling tests. The circulating fluid in the cooling garment was provided during exercise to the head (6% body surface area [BSA]), torso (22% BSA), and thighs (44% BSA) and manipulated under three methods: (a) CC, (b) pulsed cooling (PC), and (c) PC activated by mean skin temperature (T(sk)) control (PC(skin)). TC and TS ratings were recorded every 20 min during the 80-min test. RESULTS: TC and TS ratings were not different for PC(skin) and CC; thus the participants perceived PC(skin) as being similar to CC. TS was significantly warmer with PC than with PC(skin) and CC (p < .001). In PC(skin), T(sk) was significantly higher than in PC and CC (p < .001), and PC(skin) was rated as being not as warm as PC according to TS. CONCLUSION: This indicates that the PC(skin) method was perceived as being as cool as CC and cooler than PC. APPLICATION: These findings indicate that the PC(skin) cooling method is an acceptable alternative to CC and PC based on human perceptions.