USAD: undetectable steganographic approach in DCT domain

In this work, we propose a new adaptive chaotic steganographic method based on the Discrete Cosine Transform (DCT) and a reversible mapping function. The mapping function is used to map the secret bits into their corresponding symbols. This mapping technique has to preserve the same dynamics, properties and distribution of the original DCT coefficients. The novelty of our approach is based on the adaptive selection phase of embedding spots. This selection is established through a blindness condition which is applied over each image of the database. The proposed embedding scheme within the middle DCT coefficients shows lower probability of detection and higher flexibility in extraction. We evaluate the detection of our method using the Ensemble Classifiers and a set of frequency and spatial domain feature extractors such as the Spatial domain Rich Model (SRM) features, Chen et al.'s 486-dimensional both inter- and intra-block Markov-based features and Liu's 216-dimensional adaptive steganography-based features.     

Optimal joint design of orthonormal real valued short time block code and linear transceiver

The main contribution of this paper is to propose an optimal joint design of an orthonormal real valued short time block code and a linear transceiver for multi-input/multi-output (MIMO) wireless digital communication systems. Firstly, a relaxed zero forcing condition based on both the short time block code and the linear transceiver is optimally derived via the Karhunen–Loève Transform (KLT) approach. The relaxed zero forcing condition guarantees that there is no transmission error under a noise free environment. Secondly, the linear transceiver is optimally designed via the orthogonal Procrustes approach. In particular, the transmission power gain is minimised subject to a specification on the ratio of the signal gain to the noise gain as well as to the relaxed zero forcing condition. Computer numerical simulation results show that our proposed optimal joint design of the orthonormal real valued short time block code and the linear transceiver can significantly improve the performances of MIMO wireless digital communication systems.     

pFFT方法在波浪与结构作用中的不规则频率消除技术

对于求解波浪与大型结构物作用的pFFT方法,即预修正快速傅里叶变换方法(Pre-corrected Fast Fourier Transform),该文提出了消除"不规则频率"影响,从而保证在各频率下均可得到正确解的求解技术。该方法通过在内水面上配置源点的方法得到了唯一解的积分方程,并通过叠加物体内部积分方程而得到了便于求解的方形矩阵。算例表明:该方法能够消除"不规则频率"的影响,在整个频率内均可得到精确的计算结果;对于大型计算,在计算效率和内存空间的使用上,均较传统的高阶边界元方法有很大优势。     

Reliability of an Independent Component,s-Spare System with Exponential Life Times and General Repair Times

In this paper, the reliability of a system with N independent components supplied with a pool of s spares is investigated. The components have an exponential life time distribution and the failed components are repaired, one at a time, with a general repair time distribution. Numerical results are presented for the mean time to system failure (system is said to fail when a component fails with no spare available) and the reliability of the system in some special cases of interest.     

Fuzzy measures and generalized Möbius transform

Generalized Möbius transform is recalled and applied in some special cases. The relationship with the standard Möbius transform is shown. By means of the generalized Möbius transform, a general concept of k -order additivity independent of the cardinality of the underlying space is introduced. The relationship of the Choquet integral and the Lebesgue integral by means of the generalized Möbius transform is clarified. Also possibilistic Möbius transform and k -order possibility measures are introduced. Finally, some examples are given, including the characterization of de Finetti's discrete lower probabilities.     

热连轧交交变频全数字矢量控制系统故障处理与改造

本文着重叙述了我厂主传动交交变频系统控制装置的构造及其功能,另对一些常见故障进行介绍和分析,并列出一些成功改造试点,供大家参考。     

基于简化SIFT的口服液杂质检测防抖方法

在口服液灯检机杂质检测系统中,口服液瓶体由于履带搓瓶的急停会有轻微的抖动,造成高速工业摄像机拍摄的前后两帧口服液瓶体图像中位于相同空间位置的像素无法重合在一起,导致前后两帧图像做差分结果出现错误。由于口服液中的杂质很小,一般会达到微米级别,因此机械的扰动以及口服液瓶体上的污点都有可能因位置偏差对检测结果造成影响。采用尺度不变特征检测（SIFT）对系统采集的前后两帧图像进行位置配准。SIFT算法稳定性精度很高,适用于高精度口服液杂质检测系统。基于抖动幅度微弱,对该算法进行了一定的改进与简化,以获得最佳配准结果。在实际检测过程中算法稳定,检测结果准确率很高。     

Several variants of Kalman Filter algorithm for power system harmonic estimation

This paper presents the maiden application of a variant of Kalman Filter algorithm known as Local Ensemble Transform based Kalman Filter (LET-KF) for power system harmonic estimation. The proposed algorithm is applied for estimating the harmonic parameters of a power signal containing harmonics, sub-harmonics, inter-harmonics in presence of white Gaussian noise. These algorithms are applied and tested for both stationary as well as dynamic signals containing harmonics. The LET-KF algorithm reported in this paper is compared with the earlier reported Kalman Filter based algorithms like Kalman Filter (KF) and Ensemble Kalman Filter (EnKF) algorithms for harmonic estimation. The proposed algorithm is found superior than the reported algorithm for its improved efficiency and accuracy in terms of simplicity and computational features, since there are less multiplicative operations, which reduces the rounding errors. It is also less expensive as it reduces the requirement of storing large matrices, such as the Kalman gain matrix used in other KF based methods. Practical validation is carried out with experimentation of the algorithms with the real time data obtained from a large paper industry. Comparison of the results obtained with KF, EnKF and LET-KF algorithms reveals that the proposed LET-KF algorithm is the best in terms of accuracy and computational efficiency for harmonic estimation.     

Fault diagnosis of rolling bearings using a genetic algorithm optimized neural network

In rotary complex machines, collapse of a component may inexplicably occur usually accompanied by a noise or a disturbance emanating from other sources. Rolling bearings constitute a vital part in many rotational machines and the vibration generated by a faulty bearing easily affects the neighboring components. Continuous monitoring, fault diagnosis and predictive maintenance, is a crucial task to reduce the degree of damage and stopping time for a rotating machine. Analysis of fault-related vibration signal is a usual method for accurate diagnosis. Among the resonant demodulation techniques, a well-known resolution often used for fault diagnosis is envelope analysis. But, usually this method may not be adequate enough to indicate satisfactory results. It may require some auxiliary additional techniques. This study suggests some methods to extract features using envelope analysis accompanied by Hilbert Transform and Fast Fourier Transform. The proposed artificial neural network (ANN) based fault estimation algorithm was verified with experimental tests and promising results. Every test was initiated with a reference ANN architecture to avoid inappropriate classification during the evaluation of fitness value. Later, ANN model was modified using a genetic algorithm providing, an optimal skillful fast-reacting network architecture with improved classification results.     

Frequency domain image analysis for the characterization of porous products

Many pharmaceutical products are obtained via freeze-drying of liquid solutions to obtain stable long lasting preparations. The freeze-dry process produces porous cakes whose structure strongly depends on the freezing phase, so that monitoring and optimizing this phase can help both reducing the product cost and insuring its constant quality. Nowadays the optimization is usually performed by determining the cake mass transfer coefficient via a costly process in pilot plants, while the quality is assured only by controlling the process conditions. This paper describes an alternative way of approximately estimating the mass transfer coefficient, which is based on the observation of the product structure by a simple electron microscope followed by a frequency domain imaging process. While the process has been designed and characterized specifically for pharmaceutical products, the proposed approach can be used in several other fields where the characteristics of porous material have to be monitored.