Applications of kriging to image sequence coding

Kriging is a linear interpolation method used by geostatisticians. In this paper we show that it can be successfully applied to image sequence coding. First we apply it to texture coding and we improve these preliminary results with an optimization method that we have named ‘inverse kriging’. Then we apply kriging and inverse kriging to motion vector fields, which are by essence smooth within an object. We show an application of these tools in the framework of the active mesh coding scheme developed within the RACE/Morpheco project.     

电路理论在电气工程中的若干应用

电路理论的发展,充分体现了理论来源于实践,又反过来指导实践的过程.在教学过程中,加强实际应用方面的举例,会使教学过程更加生动.本文通过给出动态电路、非正弦电路、谐振电路和三相电路等电路理论,在整流滤波、电容器交流耐压实验和高压柜中互感器特殊连接等电气工程中的若干应用,为电路理论教学提供一些工程应用方面的例子.     

基于混沌的快速格雷码分段置乱视频加密算法

提出了一种基于混沌动力系统的按格雷码表顺序分块对视频图像进行数据置乱的完全加密方法。首先采用Chebyshev映射和Logistic映射相互迭代的方法产生混沌二值密钥,有效的克服了一维混沌动力系统中的平凡密钥和拟平凡密钥现象,并用此密钥对主要视频图像信息进行一次一密完全加密,然后利用格雷码序列的良好的空间遍历性和易生成性来对主要数据进行置乱,另外加密时保留了原数据的主体格式和大小。实验结果表明,算法安全性高,可有效抵抗已知明文攻击,速度快,加密后可播放,且可移植性良好。     

激光技术在航天工程中的应用及对策

激光技术在航天工程中具有重要的应用。对激光技术在航天材料加工、航天器空间环境效应地面模拟试验和航天器有效载荷上的应用进行了分析;对航天工程在激光晶体材料、激光薄膜材料、激光透明陶瓷材料及激光光纤材料等的需求和对策进行了探讨;对激光器系统在空间真空、温度交变、粒子辐射、太阳电磁辐射、等离子体以及振动等环境下的适应性及对策进行了研究。给出了建议,即应该进一步加强强激光材料的基础科学研究,研制性能优异的激光材料与有效载荷,加强激光器系统与载荷的空间环境适应性研究。     

复扰码的应用

3G的两个主流标准WCDMA和cdma2000 1x都在信号处理过程中选用了复扰码。依照论文的分析,复扰码除了有扰码的常规作用外,还能用于构成两个AM正交发送分集(OTD)信号,以及克服电波传输衰落。另外,复扰码的引入,还可有效地降低调制信号的峰均比,进一步改善系统性能。     

空间激光通信中高速伪随机序列及多路器

在开展综合信息系统演示试验前,为了实现激光通信系统的单独测试,需对模拟的各种载荷选择性输出及对误码率进行测试。研制了一种基于FPGA的嵌入式智能多路器及高速伪随机序列生成器,设计高速并串转换电路及时钟电路实现高速伪随机序列的传输,速度可达3 Gbps,用于误码率测试。其中高速的伪随机序列速率智能可调,速率范围为750 M到3 G。设计兼容多种电平的差分多路器,数据传输的类型通过多路器选择性输出,输出的电平为固定的LVPECL。如:视音频的串行数据流,伪随机序列,模拟数据源。     

WCDMA系统扰码规划原理与实例

在简述WCDMA网络特点的基础上，对WCDMA无线网络规划中的扰码规划原理进行了详细的阐述，另外在实际网络规划时，对扰码规划要考虑的问题进行了详细说明，并给出扰码规划的实例。     

现代图像置乱程度衡量方法综述

图像置乱加密的目的是实现图像的安全传输或保存,现在许多算法都认为自身具有很高的安全性,可以抵抗多种攻击.置乱度就是衡量图像置乱程度的客观方法,置乱度越高则该算法就越有效.将衡量图像置乱程度的方法分为五大类,并分别加以系统论述,分析了各种方法的优缺点.     

电视信号加扰解扰方式的分析

具体分析了电视信号的加解扰方式,并提出了选择加解扰方案时要充分考虑“五性”,即隐匿性、还原性、安全性、扩展性和廉价性。     

基于SRG的快速图像分割算法研究与实现

针对传统的SRG算法实时性和准确性不足,提出了一种模拟自然界生态中病毒感染过程的智能快速图像分割算法,并在VC＋＋6平台上实现。该算法基于传统SRG图像分割原理,一方面可以自动探测生长点,并且可根据背景的亮暗动态更新参数,对光线不均匀的图像也可进行分割;另一方面仅通过一次对图像的全局遍历搜索,便可逐一将目标从背景中分割并且作标记。实验结果表明,与传统阈值算法相比,该算法在提高图像分割速度的同时,在不同背景中分割图像的准确性更高。     

Low-frequency performance of guided scrambling DC-free codes

We analyze the effect of coding parameters on low-frequency suppression in guided scrambling (GS) dc-free codes based on computer simulation. Simple expressions to accurately estimate the sum variance and low-frequency spectrum-weight of these codes are developed. Systematic design of GS dc-free codes is discussed.     

Applications of space communications technology to critical human needs: rescue, disaster relief, and remote medical assistance

The applications of space communications technology to various critical human needs are discussed. Satellite communications, telemetry, and biotelemetry have provided timely and crucial communications capabilities over remote distances. The use of satellite/beacon systems have been used for disaster relief as well as search and rescue operations. The combination of telemetry and electronic medical systems (telemedicine) have augmented existing health care delivery and have provided consultation links between remotely located health care specialists working with patients and physicians at a central location. This has been expanded into networks to respond to victims of disasters in need of critical medical assistance with the hope that with further work, telemedicine may become available to all nations through an international network.     

A new analytical subthreshold model of SRG MOSFET with analogue performance investigation

For the first time, a pseudo-two-dimensional (2D) approach is extended from a rectangular device structure to a cylindrical one. A pseudo-2D model applying Gauss's law in the cylindrical channel depletion region for undoped or lightly doped surrounding gate (SRG) silicon metal oxide semiconductor field effect transistor (MOSFETs) working in subthreshold regime is presented. From this pseudo-2D analysis, electrostatic potentials, current characteristics, the threshold voltage roll-off, the drain-induced barrier lowering and the subthreshold swing are explicitly modelled. The obtained analytical model has been extended to develop a model for transconductance-to-drain current ratio (g _m/I _d) in weak inversion regime. Analogue figures of merit of SRG MOSFETs are studied, including transconductance efficiency g _m/I _d, intrinsic gain and output resistance. The trends related to their variations along the downscaling of dimension are provided. In order to validate our model, the modelled expressions are compared with the simulated characteristics obtained from ATLAS device simulator.     

m序列与Gold序列比较

作为扩频通信中常用的伪随机序列，m序列与Cold各有各自的特点，但同时也存在一些不同，现从基本原理、性能和构造方法出发，着重比较了两者在性能方面的区别，并对两者的相关性用MATLB进行了仿真。     

Arnold变换在非方阵图像置乱中的应用

在信息安全领域,图像加密近年来越来越被重视。Arnold变换作为一种图像置乱的方法,在方阵数字图像置乱上被广泛使用。本文对基于Arnold变换的图像置乱及恢复进行研究,并针对本文所用图像的特点,提出了分块Arnold变换的方法,实现了Arnold变换在非方阵图像上的扩展。与常用的扩充方法进行效率上的对比,通过实验验证了Arnold变换用于非方阵图像置乱的可行性。     

A phase scrambling scheme for suppression of peak to average power ratio for OFDM

The complex-valued modulating vectors for the subcarrlers consist of two kinds of components: One is the information-bearing components superposed with pseudo-randomized phases and the other is the suppression components with specified scrambling phases. The pseudorandomized phases are generated according to the predefined polynomial and mapping function whereas the scrambling phases are from a gradient algorithm. The simulation results verify the rationality and validity of the phase scrambling.     

Recent advances in theory and applications of scrambling techniquesfor lightwave transmission

This paper discusses recent advances in the theory and applications of scrambling techniques for digital lightwave transmission. It introduces the theories of sequence space and shift register generator (SRG) space which enable systematic analysis and mathematical manipulation of the behavior of sequences in general and the related SRG's. It discusses the behavior and realization of frame synchronous scrambling (FSS) and distributed sample scrambling (DSS) with emphasis on parallel sequences and the related parallel SRG's (PSRG). In addition, it describes self synchronous scrambling (SSS). Then the paper applies the theories to today's lightwave transmission systems by demonstrating practical parallel designs of FSS for SDH/SONET transmission, DSS for cell-based ATM transmission, and SSS for SDH-based ATM transmission. It finally considers how DSS can be used for scrambling of mixed isochronous and nonisochronous data in future high-speed data networks. The paper employs various new concepts and terminology, such as PSRG engine, generating vector discrimination matrix, (M,N) PSRG, sampling vector, correction vector, correction matrix, predictable scrambling concurrent sampling, and immediate correction     

Reliability of a space shuttle subject to space erosion

In this paper, we study a stochastic model for an intermittently used spacecraft, subject to space erosion. We propose a suitable reliability criterion, compatible with a light-as-possible criterion, in order to determine an optimal choice of a parameter of the Weibull distribution. The optimal value assures a survival of K missions with a reliability of at least 90%.