无线嵌入式在大型设备故障诊断中的应用

文中介绍的无线嵌入式系统是针对某大型装备对故障诊断的要求,实现在线实时或历史数据监测、报警和诊断分析于一体的高效、智能化的故障诊断系统,提出一种在线监测与故障诊断的方案;各检测终端固化于装备上,主机与各检测终端通过无线网络通讯,从而免去了主机与各终端间的连接电缆,使系统实现了智能化和小型化;该系统在实时性智能化的同时,具有不同设备间应用的较强通用性;同时详细介绍了系统的软硬件组成和工作原理.     

燃气发电机组状态监测及故障诊断监控系统研究

作者研发了一套燃气发电机组状态监测及故障诊断系统,本系统实现了燃气发电机组振动数据和性能参数同时采集,共同分析的功能,建立了振动故障诊断数据库,实现对燃气轮机主要部件的故障诊断.并通过对某油田现场的9台燃气发电机组进行测试,结果表明,本系统的软件功能和硬件功能可以满足燃气轮机状态监测及其故障诊断的要求.     

虚拟仪器下回热系统监测与故障诊断系统研究

汽轮机组回热系统是火电厂热力系统的核心,回热系统故障已成为影响汽轮机组稳定发电满负荷发电的主要原因之一.为保证火电厂回热系统的安全经济运行,实现远程状态监测、故障诊断及故障排除,采用虚拟仪器系统作为开发平台,构建了火电厂回热系统远程状态监测与多种诊断知识的故障诊断专家系统.在介绍虚拟仪器特点的基础上,详细阐述了系统监测参数、系统组成、系统功能及设计.实践证明,该系统具有有效性、灵活性和可扩展性等特点.     

混合故障诊断专家系统

对大型复杂生产系统进行状态监测和故障诊断难以用单一诊断理论和技术实现.将协同计算机网络、专家系统、神经网络和小波分析等先进理论和技术有机地结合起来,研究和构造了模块化的混合故障诊断专家系统,以实现对某钢厂大型复杂自动化冷轧生产线进行状态监测和故障诊断.研究结果表明,混合专家系统为大型复杂系统的状态监测和故障诊断提供了崭新而有效的技术手段.     

HDTV编码器测试系统的设计与硬件实现

高清晰度电视（HDTV）编码器测试系统用于HDTV编码器各模块电路的调试与故障诊断，是HDTV编码器研制过程中不可缺少的测试设备。该系统通过向HDTV各模块电路发送测试用的数字视频码流，并接收和分析经过各模块电路处理后近视频码流，从而确定HDTV编码器各单元电路是滞正常。该文提出并实现了一个HDTV编码器测试系统，主要介绍了硬件部分的设计与实现。     

嵌入式智能代理用于装备远程故障诊断

针对目前武器装备故障诊断过程中存在的诸多问题,为了从根本上满足智能监测与诊断的需要,提出了一种基于嵌入式智能代理的远程故障诊断方式,在该方式下,通过利用现代互联网技术、嵌入式智能系统技术,系统可根据设备的具体工作情况,提取并传输诊断、预测和决策所需的信息,以实现异地间的监测,优化维护方案;通过对智能代理理论的研究提出了远程故障诊断嵌入式智能代理,并具体研究了该模型的硬件实现方案.     

航空发动机气路故障诊断

介绍了航空发动机气路故障诊断基准参数的选取和监测参数偏差的产生方法,探讨了采用故障相似系数进行气路故障隔离和辨识的方法,并用某型涡扇发动机实测数据验证了该方法的有效性.相似系数不仅具有明确的物理意义,而且使得故障诊断系统构造简便,故障模式扩展容易.采用相似系数进行故障模式隔离不必要求监测参数的个数大于故障模式个数.在隔离故障模式的基础上,进一步辨识发动机部件性能衰退程度,对气路故障的诊断更为深入.     

基于BIT技术的PCU故障诊断和性能监测系统

针对卫星电源控制器(PCU)存在故障诊断和性能监测能力有限的问题,对某卫星电源控制器进行了测试性设计,搭建了基于BIT技术的PCU在轨故障诊断和性能监测系统。BIT由3个模拟板和1个核心板组成,模拟板可对数十路模拟信号进行高速采样,核心板运行故障诊断和性能监测算法,并进行数据存储、数据打包、通信等工作,故障诊断和性能监测结果在打包后发送至通信接口。验证实验表明,在不影响PCU正常工作的前提下,系统可对PCU的故障进行准确检测和定位,诊断速度快,同时可对PCU的母线电压纹波等性能进行监测。     

基于Web的设备监测与故障诊断系统的设计与实现

设备的故障诊断技术在现代化的大生产中越来越受到重视,通过基于Web的易于扩展的三层客户/服务器结构(B/S)模式的故障诊断技术的应用研究和具体实现过程,体现了基于Web模式进行设备故障诊断的优点和可行性,提出了一种设备监测与故障诊断的方法.通过组建监测诊断网络系统,可以实现仪器互联,资源共享,降低测试成本,提高测试效率.随着网络技术和数据库技术的发展,基于网络的监测诊断系统是仪器技术发展的必然趋势.     

基于多Agent的智能监测与诊断技术

由于Agent系统是一个具有自主性、反应性、主动性和社会性的基于硬件和软件的计算机系统,其具有强的环境适应性,能够提高故障诊断的准确率,文中把Agent技术引入智能故障诊断之中。本文以诊断Agent为基础,构造了基于多Agent的监测与诊断模型,并对协作诊断中的任务分解策略、通信机制和诊断结果的综合等关键技术进行了分析,同时对模型实现中的软件机制进行了研究,从而为智能监测诊断的实现提供了支持。     

基于深度小波去噪自动编码器的轴承智能故障诊断方法

针对原始振动数据无监督特征学习问题,提出一种深度小波去噪自动编码器与鲁棒极限学习机相结合的滚动轴承的智能故障诊断方法.利用小波函数作为非线性激活函数设计小波去噪自动编码器,从而有效地捕获信号特征;利用多个小波去噪自动编码器构造一个深度小波去噪自动编码器来增强无监督特征学习能力;采用鲁棒极限学习机作为分类器,对不同的轴承...     

Gaussian Mixture Kalman Predictive Coding of Line Spectral Frequencies

Gaussian mixture model (GMM)-based predictive coding of line spectral frequencies (LSFs) has gained wide acceptance. In such coders, each mixture of a GMM can be interpreted as defining a linear predictive transform coder. In this paper, we use Kalman filtering principles to model each of these linear predictive transform coders to present GMM Kalman predictive coding. In particular, we show how suitable modeling of quantization noise leads to an adaptive a posteriori GMM that defines a signal-adaptive predictive coder that provides improved coding of LSFs in comparison with the baseline recursive GMM predictive coder. Moreover, we show how running the GMM Kalman predictive coders to convergence can be used to design a stationary GMM Kalman predictive coding system which again provides improved coding of LSFs but now with only a modest increase in run-time complexity over the baseline. In packet loss conditions, this stationary GMM Kalman predictive coder provides much better performance than the recursive GMM predictive coder, and in fact has comparable mean performance to a memoryless GMM coder. Finally, we illustrate how one can utilize Kalman filtering principles to design a postfilter which enhances decoded vectors from a recursive GMM predictive coder without any modifications to the encoding process.     

United coding method for compound image compression

This paper proposes a compound image coding method named united coding (UC). In UC, several lossless coding tools such as dictionary-entropy coders, run-length encoding (RLE), Hextile, and a few filters used in portable network graphics (PNG) format are united into H.264 like intraframe hybrid video coding. The basic coding unit (BCU) has a size typically between 16?×?16 pixels to 64?×?64 pixels. All coders in UC are used to code each BCU. Then, the lossless coder that generates minimum bit-rate (R) is chosen as the optimal lossless coder. Finally, the final optimal coder is chosen from the lossy intraframe hybrid coder and the optimal lossless coder using R-D cost based optimization criterion. Moreover, the data coded by one lossless coder can be used as the dictionary of other lossless coders. Experimental results demonstrate that compared with H.264, UC achieves up to 20 dB PSNR improvement and better visual picture quality for compound images with mixed text, graphics and natural picture. Compared with lossless coders such as gzip and PNG, UC can achieve 2–5 times higher compression ratio with just a minor loss and keep partial-lossless picture quality. The partial-lossless nature of UC is indispensable for some typical applications, such as cloud computing and rendering, cloudlet-screen computing and remote desktop, where lossless coding of partial image regions is demanded. On the other hand, the implementation complexity and cost increment of UC is moderate, typically less than 25 % of a traditional hybrid coder such as H.264.     

Design of integrated multimedia compression and encryption systems

Two approaches for integrating encryption with multimedia compression systems are studied in this research, i.e., selective encryption and modified entropy coders with multiple statistical models. First, we examine the limitations of selective encryption using cryptanalysis, and provide examples that use selective encryption successfully. Two rules to determine whether selective encryption is suitable for a compression system are concluded. Next, we propose another approach that turns entropy coders into encryption ciphers using multiple statistical models. Two specific encryption schemes are obtained by applying this approach to the Huffman coder and the QM coder. It is shown that security is achieved without sacrificing the compression performance and the computational speed. This modified entropy coding methodology can be applied to most modern compressed audio/video such as MPEG audio, MPEG video, and JPEG/JPEG2000 images.     

Implementation of variable bitrate data hiding techniques on standard and proposed GSM 06.10 full rate coder and its overall comparative evaluation of performance

Paper deals with implementation of variable bit rate steganographic data transmission over ETSI GSM 06.10 FR coder at five different bitrates. Then, few modifications are suggested in Regular Pulse Excitation section of ETSI GSM FR coder which ultimately claims to produce state of the art proposed GSM FR coder. In contrast with ETSI GSM FR coder, proposed coder also exhibits same bit rate steganographic data transmission. Here, in order to facilitate the same, few RPE pulses are identified and being utilized for embedding and hiding the information bits into them. Key element of this research is to allow for joint speech coding and data hiding and that is accomplished with two different approaches like Fixed and Joint Approach. These both approaches are implemented on both Standard and Proposed coders for their overall analytical evaluation of performance using Subjective (Mean opinion Score and Degraded MOS) and Objective (Perceptual Evaluation of Speech Quality) analysis. Small data information is represented as stego signal which can be embedded over different encoded wave files (chosen from NOIZEUS corpus) that serve as carrier signal. Simulation results for both coders reveal the trade off between data embedding rate and recovered speech quality (for both approaches). It is quite evident from both Subjective and Objective analysis that proposed coder offers comparable performance at the same time with lesser simulation delay because of its inherent constructional difference. It remains the fact that for both the coders, Joint approach performs better but at the cost of more simulation delay.     

通用的高性能算术编码器

文中基于成熟的ＱＭ算术编码器,提出了对称二叉树的编码方式ＳＴＱＭ和最优二叉树的编码方式ＯＴＱＭ。ＳＴＱＭ与ＯＴＱＭ均是大符号集熵编码器。它们不仅保持了ＱＭ编码器的超过９６％的编码效率,也保持了它高速运算的特性。基中ＯＴＱＭ可以动态的调整码树结构,使得编码速度达到理论最优值。ＳＴＱＭ由于可并行性和逻辑线路设计简单等特点,使之适合于做动态旬图像的基于专用硬件设计的熵编码模块。     

Structures for SNR scalable speech coding

SNR scalable speech coding is desirable for a number of network multimedia applications, but relatively few SNR-scalable speech coders exist for operation at rates below 16 kb/s. We investigate several SNR scalable source coding structures and define the new concepts of dependent and independent SNR scalability, where independent SNR scalable coders depend on the core layer coder only through the core layer output. Independent SNR scalable structures offer the possibility of providing bit rate scalable functionality to existing nonscalable coders and standards. We show that the MPEG-4 scalable coders are examples of dependent SNR scalable coders, and we introduce a new independent SNR scalable coder called CELPTree, which has the additional advantage of being low delay. We compare the performance of the MPEG-4 coders and CELPTree for both clean and noisy speech, and we examine the effects of frequency-weighted distortion measures in the enhancement layers of SNR scalable speech coders.     

在TMS320C6x系列DSP上实现G．729算法

在研究ITU-T的G．729CS-ACELP语音编码算法基础上，本文介绍了使用TI公司的TMS320C6x系列DSP实现该算法的一些问题以及一些应用中的具体优化技术，这在一定程度上降低了该算法的计算复杂度，而输出语音仍然保持了很高的合成品质。然后，本文讨论了如何在一个电信级 的应用内核上对该语音编码算法进行多声道扩展的问题，该多通道编码系统基本能达到实用要求。最后，在实时MCPS、内存要求、处理延时和实时性能等方面对该DSP实现的编码器做了一个评价，可以作为其他语音编码器开发的参考。     

A class of coders based on GSM

Using the definition of gsm and finite translators, a new class of coders is proposed. In the first part it is shown that ifM is a weakly-deterministic coder, thenM ^–1 is also a coder. In the second part, this class of coders is used for solving a problem of secrets transmission.     

Rate-distortion理论在H.264编码器中的应用

编码模式的选择是视频编码器控制的一个重要功能，它直接决定了编码器的性能和效率。新的视频压缩协议H．264协议比其它视频压缩协议提出了更多的编码模式，这就决定了H．264编码器不能像H.263编码器一样，通过比较某个门限值来简单地决定采用哪种编码模式。另一方面，根据Rate-distortion理论，在失真度与比特率之间存在一个最佳折衷点。如果确定了合适的拉各朗日(Lagrangian)参数，就能利用拉各朗日公式找到这个最佳折衷点。把这一理论作为H.264编码器的模式选择算法，将会使H．264编码器根据图像内容自适应地选择最佳的编码模式，达到最佳的压缩效果。