Component-scaled signal reconstruction for enhanced noise filtration

This research introduces a procedure for signal denoising based on linear combinations of intrinsic mode functions (IMFs) extracted using empirical mode decomposition (EMD). The method, termed component-scaled signal reconstruction, employs the standard EMD algorithm, with no enhancements to decompose the signal into a set of IMFs. The problem of mode mixing is leveraged for noise removal by constructing an optimal linear combination of the potentially mixed IMFs. The optimal linear combination is determined using an optimization routine with an objective function that maximizes and minimizes the information and noise, respectively, in the denoised signal. The method is demonstrated by applying it to a computer-generated voice sample and the displacement response of a cantilever beam with local stiffness nonlinearity. In the first application, the noise is introduced into the sample manually by adding a Gaussian white-noise signal to the signal. In the second application, the response of the entire beam is filmed using two 1-megapixel cameras, and the three-dimensional displacement field is extracted using digital image correlation. The noise in this application arises entirely from the images captured. The proposed method is compared to existing EMD, ensemble EMD, and LMD based denoising approaches and is found to perform better.

Double Feature Extraction Method of Ship-Radiated Noise Signal Based on Slope Entropy and Permutation Entropy

In order to accurately identify various types of ships and develop coastal defenses, a single feature extraction method based on slope entropy (SlEn) and a double feature extraction method based on SlEn combined with permutation entropy (SlEn&PE) are proposed. Firstly, SlEn is used for the feature extraction of ship-radiated noise signal (SNS) compared with permutation entropy (PE), dispersion entropy (DE), fluctuation dispersion entropy (FDE), and reverse dispersion entropy (RDE), so that the effectiveness of SlEn is verified, and SlEn has the highest recognition rate calculated by the k-Nearest Neighbor (KNN) algorithm. Secondly, SlEn is combined with PE, DE, FDE, and RDE, respectively, to extract the feature of SNS for a higher recognition rate, and SlEn&PE has the highest recognition rate after the calculation of the KNN algorithm. Lastly, the recognition rates of SlEn and SlEn&PE are compared, and the recognition rates of SlEn&PE are higher than SlEn by 4.22%. Therefore, the double feature extraction method proposed in this paper is more effective in the application of ship type recognition.

Noise Assisted Image Encryption and Decryption using 2-D Chaotic System

In this paper, a new two-dimensional (2-D) chaos-based color image encryption and decryption scheme is proposed in which the noise signal is selected randomly to set the initial values for a chaotic system which also enhances the security of the system. The 256-bit hash value of noise is transformed into one-time initial values for the state variables of this proposed chaotic system. XOR operation is further carried out to diffuse the pixels. Finally, statistical and security analyses are performed for understanding the effectiveness of the proposed system. Experimental results confirm that the proposed chaos-based cryptosystem is efficient and suitable for information (image) transmission in a highly secured way.

Issues of technical implementation of ground-based microwave radiometric system calibration

The theoretical bases of a method of carrying out calibration of microwave radiometric system on a noise signal of the external noise generator are analysed, the parameters setting value of gain of antenna temperature at introduction in structure of system of such external source of a calibration signal are determined. The questions of technical realization of an external source of a calibration signal for microwave radiometric system are considered, the structural scheme is presented, the place of its arrangement in structure of the antenna is determined. The necessity of using a horn antenna to create directional radiation towards the mirror antenna emitter is shown. The data on the design of such a calibration signal source for the case of its use in a three-band microwave radiometric system with the reception of a noise signal at the common antenna aperture and a sequential separation of the input signals of the three bands in the feeder path of the common mirror irradiator are presented. The influence of the design and, accordingly, the directional properties of the horn antenna of a microwave radiometric system calibration signal source on the coefficient characterizing the radiation divergence created by the noise generator horn, as well as the frequency properties of this coefficient are analysed. The results of measurements of radio-thermal radiation by a three-band microwave radiometric system when two calibration periods with reception of a radio-noise signal from an external calibration signal source located at the base of the antenna mirror are presented.

Fluctuations and Pinning for Individually Manipulated Skyrmions

We numerically examine the dynamics of individually dragged skyrmions interacting simultaneously with an array of other skyrmions and quenched disorder. For drives just above depinning, we observe a broadband noise signal with a 1/f characteristic, while at higher drives, narrowband or white noise appears. Even in the absence of quenched disorder, the threshold force that must be applied to translate the driven skyrmion is finite due to elastic interactions with other skyrmions. The depinning threshold increases as the strength of the quenched disorder is raised. Above the depinning force, the skyrmion moves faster in the presence of quenched disorder than in a disorder-free system since the pinning sites prevent other skyrmions from being dragged along with the driven skyrmion. For strong pinning, we find a stick-slip motion of the driven skyrmion which produces a telegraph noise signature. The depinning threshold increases monotonically with skyrmion density in the absence of quenched disorder, but when pinning is present, the depinning threshold changes nonmonotonically with skyrmion density, and there are reentrant pinned phases due to a competition between pinning induced by the quenched disorder and that produced by the elastic interactions of the skyrmion lattice.

An N-Port Universal Multimode Optical Router Supporting Mode-Division Multiplexing

Optical network-on-chip (ONoC) is based on optical interconnects and optical routers (ORs), which have obvious advantages in bandwidth and power consumption. Transmission capacity is a significant performance in ONoC architecture, which has to be fully considered during the design process. Relying on mode-division multiplexing (MDM) technology, the system capacity of optical interconnection is greatly improved compared to the traditional multiplexing technology. With the explosion in MDM technology, the optical router supporting MDM came into being. In this paper, we design a multimode optical router (MDM-OR) model and analyze its indicators. Above all, we propose a novel multimode switching element and design an N-port universal multimode optical router (MDM-OR) model. Secondly, we analyze the insertion loss model of different optical devices and the crosstalk noise model of N-port MDM-OR. On this basis, a multimode router structure of a single-mode five-port optical router is proposed. At the same time, we analyze the transmission loss, crosstalk noise, signal-to-noise radio (OSNR), and bit error rate (BER) of different input–output pairs by inputting the 1550 nm TE0, TE1, and TE2 modes to the router.

Examination of the Non-Orthogonal Multiple Access System Using Long Short Memory Based Deep Neural Network

This paper investigates deep learning (DL) non-orthogonal multiple access (NOMA) receivers based on long short-term memory (LSTM) under Rayleigh fading channel circumstances. The performance comparison between the DL NOMA detector and the traditional NOMA method is established, and results have shown that the DL-based NOMA detector performance is far better in comparison with conventional NOMA detectors. Simulation curves are compared with the performance of the DL detector in terms of minimum mean square estimate (MMSE) and least square error (LSE) estimate, taking all realistic circumstances, except the cyclic prefix (CP), and clipping distortion into account. The simulation curves demonstrate that the performance of the DL-based detector is exceptionally good when it equals 1 when the noise signal ratio (SNR) is more than 15 dB, assuming that the DL method is more resilient to clipping distortion.

A secure encryption method of communication channel based on cloud computing technology

The traditional channel encryption method is interfered by noise signal, which leads to long encryption time and poor security. This paper proposes a communication channel security encryption method based on cloud computing technology. In order to obtain the minimum benefits of the same channel and orthogonal channel in the frequency conversion receiver, the dual input and dual output model is constructed; the influence of time domain and frequency domain on the transmission signal is analyzed, and the nonlinear transmission characteristics of the channel signal are obtained. Through cloud computing technology, the channel transmission characteristics are divided into dynamic parameters and static parameters to realize the key distribution of communication channel under cloud computing technology; the balance factor is used to provide the key for the sorted generators to realize the secure encryption of communication channel. The results show that the average error probability of the proposed method is about 0.275, and the signal-to-noise ratio is between 115 and 118 SNR.

Usage of Barkhausen Noise for Assessment of Corrosion Damage on Different Low Alloyed Steels

This study deals with corrosion damage of low alloyed feritic steels of variable strength. Three different steels of nominal yield strength 235, 700 and 1100 MPa were subjected to the variable degree of corrosion attack developed in the corrosion chamber under a neutral salt spray (NSS) atmosphere. The corrosion damage was investigated by the use of conventional metallographic observations when the thickness of corroded layer was quantified. Moreover, non-destructive magnetic technique, based on Barkhausen noise, was also employed. It was found that the rate of corrosion damage decreases along with the increasing number of days in the chamber. The similar evolution can be also found for Barkhausen noise emission and the extracted parameters from the emission. It can be reported that conventional rms value of Barkhausen noise signal as well as FWHM (full width at half maximum of Barkhausen noise envelope) can be linked with the corrosion extent, especially in the early phases of corrosion attack. The PP (peak position of Barkhausen noise envelope) values exhibit poor sensitivity.