High-concentration time–frequency analysis for multi-component nonstationary signals based on combined multi-window Gabor transform

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Qiang Wang ◽  
Chen Meng ◽  
Cheng Wang
Keyword(s):  
Optimal Solution ◽  
Iteration Process ◽  
Perfect Reconstruction ◽  
Gabor Transform ◽  
Zak Transform ◽  
High Concentration ◽  
Content Type ◽  
Nonstationary Signals ◽  
Time Frequency ◽  
Optimization Function

PurposeThis study aims to reveal the essential characteristics of nonstationary signals and explore the high-concentration representation in the joint time–frequency (TF) plane.Design/methodology/approachIn this paper, the authors consider the effective TF analysis for nonstationary signals consisting of multiple components.FindingsTo make it, the authors propose the combined multi-window Gabor transform (CMGT) under the scheme of multi-window Gabor transform by introducing the combination operator. The authors establish the completeness utilizing the discrete piecewise Zak transform and provide the perfect-reconstruction conditions with respect to combined TF coefficients. The high-concentration is achieved by optimization. The authors establish the optimization function with considerations of TF concentration and computational complexity. Based on Bergman formulation, the iteration process is further analyzed to obtain the optimal solution.Originality/valueWith numerical experiments, it is verified that the proposed CMGT performs better in TF analysis for multi-component nonstationary signals.

A nonlinear magnetic circuit model for periodic eddy current problems using T,ϕ-ϕ formulation

2017 ◽  
Vol 36 (3) ◽  
pp. 649-664 ◽  
Author(s):  
Rene Plasser ◽  
Gergely Koczka ◽  
Oszkár Bíró
Keyword(s):  
Eddy Current ◽  
Magnetic Circuit ◽  
Iteration Process ◽  
Equation System ◽  
Circuit Model ◽  
Computational Time ◽  
Combined Method ◽  
3D Fem ◽  
Content Type ◽  
Transformer Model

Purpose A transformer model is used as a benchmark for testing various methods to solve 3D nonlinear periodic eddy current problems. This paper aims to set up a nonlinear magnetic circuit problem to assess the solving procedure of the nonlinear equation system for determining the influence of various special techniques on the convergence of nonlinear iterations and hence the computational time. Design/methodology/approach Using the T,ϕ-ϕ formulation and the harmonic balance fixed-point approach, two techniques are investigated: the so-called “separate method” and the “combined method” for solving the equation system. When using the finite element method (FEM), the elapsed time for solving a problem is dominated by the conjugate gradient (CG) iteration process. The motivation for treating the equations of the voltage excitations separately from the rest of the equation system is to achieve a better-conditioned matrix system to determine the field quantities and hence a faster convergence of the CG process. Findings In fact, both methods are suitable for nonlinear computation, and for comparing the final results, the methods are equally good. Applying the combined method, the number of iterations to be executed to achieve a meaningful result is considerably less than using the separated method. Originality/value To facilitate a quick analysis, a simplified magnetic circuit model of the 3D problem was generated to assess how the different ways of solutions will affect the full 3D solving process. This investigation of a simple magnetic circuit problem to evaluate the benefits of computational methods provides the basis for considering this formulation in a 3D-FEM code for further investigation.

scholarly journals A combined generalized Warblet transform and second order synchroextracting transform for analyzing nonstationary signals of rotating machinery

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kai Wei ◽  
Xuwen Jing ◽  
Bingqiang Li ◽  
Chao Kang ◽  
Zhenhuan Dou ◽  
...  
Keyword(s):  
Vibration Signal ◽  
Rotating Machinery ◽  
Second Order ◽  
Variable Speed ◽  
Short Time Fourier Transform ◽  
Stationary Characteristic ◽  
Nonstationary Signals ◽  
Time Frequency ◽  
Effective Technology ◽  
Short Time

AbstractIn recent years, considerable attention has been paid in time–frequency analysis (TFA) methods, which is an effective technology in processing the vibration signal of rotating machinery. However, TFA techniques are not sufficient to handle signals having a strong non-stationary characteristic. To overcome this drawback, taking short-time Fourier transform as a link, a TFA methods that using the generalized Warblet transform (GWT) in combination with the second order synchroextracting transform (SSET) is proposed in this study. Firstly, based on the GWT and SSET theories, this paper proposes a method combining the two TFA methods to improve the TFA concentration, named GWT–SSET. Secondly, the method is verified numerically with single-component and multi-component signals, respectively. Quantized indicators, Rényi entropy and mean relative error (MRE) are used to analyze the concentration of TFA and accuracy of instantly frequency (IF) estimation, respectively. Finally, the proposed method is applied to analyze nonstationary signals in variable speed. The numerical and experimental results illustrate the effectiveness of the GWT–SSET method.

Dual mass MEMS gyroscope temperature drift compensation based on TFPF-MEA-BP algorithm

Sensor Review ◽  
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Huiliang Cao ◽  
Rang Cui ◽  
Wei Liu ◽  
Tiancheng Ma ◽  
Zekai Zhang ◽  
...  
Keyword(s):  
Training Data ◽  
Experimental Result ◽  
Intrinsic Mode Functions ◽  
Temperature Drift ◽  
Connection Weight ◽  
Bp Network ◽  
Content Type ◽  
Mems Gyroscope ◽  
Time Frequency ◽  
Drift Compensation

Purpose To reduce the influence of temperature on MEMS gyroscope, this paper aims to propose a temperature drift compensation method based on variational modal decomposition (VMD), time-frequency peak filter (TFPF), mind evolutionary algorithm (MEA) and BP neural network. Design/methodology/approach First, VMD decomposes gyro’s temperature drift sequence to obtain multiple intrinsic mode functions (IMF) with different center frequencies and then Sample entropy calculates, according to the complexity of the signals, they are divided into three categories, namely, noise signals, mixed signals and temperature drift signals. Then, TFPF denoises the mixed-signal, the noise signal is directly removed and the denoised sub-sequence is reconstructed, which is used as training data to train the MEA optimized BP to obtain a temperature drift compensation model. Finally, the gyro’s temperature characteristic sequence is processed by the trained model. Findings The experimental result proved the superiority of this method, the bias stability value of the compensation signal is 1.279 × 10–3°/h and the angular velocity random walk value is 2.132 × 10–5°/h/vHz, which is improved compared to the 3.361°/h and 1.673 × 10–2°/h/vHz of the original output signal of the gyro. Originality/value This study proposes a multi-dimensional processing method, which treats different noises separately, effectively protects the low-frequency characteristics and provides a high-precision training set for drift modeling. TFPF can be optimized by SEVMD parallel processing in reducing noise and retaining static characteristics, MEA algorithm can search for better threshold and connection weight of BP network and improve the model’s compensation effect.

Trajectory tracking and point stability of three-axis aero-dynamic pendulum with MPC strategy in disturbance environment

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiaofeng Liu ◽  
Jiahong Xu ◽  
Yuhong Liu
Keyword(s):  
Predictive Model ◽  
Trajectory Tracking ◽  
Control Strategy ◽  
Kinematic Model ◽  
Control Variable ◽  
Optimal Solution ◽  
Intelligent Manufacturing ◽  
Pendulum System ◽  
Content Type ◽  
3D Space

Purpose The purpose of this research on the control of three-axis aero-dynamic pendulum with disturbance is to facilitate the applications of equipment with similar pendulum structure in intelligent manufacturing and robot. Design/methodology/approach The controller proposed in this paper is mainly implemented in the following ways. First, the kinematic model of the three-axis aero-dynamic pendulum is derived in state space form to construct the predictive model. Then, according to the predictive model and objective function, the control problem can be expressed a quadratic programming (QP) problem. The optimal solution of the QP problem at each sampling time is the value of control variable. Findings The trajectory tracking and point stability tests performed on the 3D space with different disturbances are validated and the results show the effectiveness of the proposed control strategy. Originality/value This paper proposes a nonlinear unstable three-axis aero-dynamic pendulum with less power devices. Meanwhile, the trajectory tracking and point stability problem of the pendulum system is investigated with the model predictive control strategy.

Cañihua (Chenopodium pallidicaule Aellen) a promising superfood in food industry: a review

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jerry Fredy Gomez Cahuata ◽  
Yessica Estefany Rosas-Quina ◽  
Erika Pachari Vera
Keyword(s):  
Food Industry ◽  
Unsaturated Fatty Acids ◽  
Protein Quality ◽  
Current Knowledge ◽  
Scientific Information ◽  
Essential Amino Acids ◽  
High Concentration ◽  
Content Type ◽  
Functional Value ◽  
Potential Applications

Purpose The purpose of this paper is to divulge the current knowledge about the nutritional and functional characteristics of Cañihua (Chenopodium pallidicaule Aellen), in addition to its potential applications in the food industry since research studies related to it are still limited compared to other cereals of greater diffusion. Design/methodology/approach The scientific information was collected from Web of Science, Scopus and Google Scholar databases, using keywords such as nutrition value of Chenopodium pallidicaule, amaranth and pseudocereals. Consistent information was selected according to its relevance, year of publication and accuracy with the topic. A total of 49 research papers were selected. Findings Cañihua is a grain with high nutritional potential, considered a superfood because it has a high protein quality, a balanced composition of essential amino acids and unsaturated fatty acids, with a high concentration of linoleic and oleic acid. Besides, it has a good level of bioactive compounds with high antioxidant capacity. However, its production and consumption are limited outside its area of origin, although its cultivation is possible under harsh conditions. Originality/value This paper, through a systematic bibliographic review, highlights the potential of cañihua to be considered in the development of food products with high nutritional and functional value. The information compiled will help researchers and professionals become aware of the importance of this grain and join forces in its processing and enhancement of its attributes.

Evaluation of the corrosion behavior of AZ31 magnesium alloy with different protein concentrations

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yucong Ma ◽  
Mohd Talha ◽  
Qi Wang ◽  
Zhonghui Li ◽  
Yuanhua Lin
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Surface Film ◽  
Energy Dispersive Spectrometer ◽  
Inhibitory Effect ◽  
Corrosion Process ◽  
High Concentration ◽  
Content Type ◽  
Atomic Force

Purpose The purpose of this paper is to study systematically the corrosion behavior of AZ31 magnesium (Mg) alloy with different concentrations of bovine serum albumin (BSA) (0, 0.5, 1.0, 1.5, 2.0 and 5.0 g/L). Design/methodology/approach Electrochemical impedance spectroscopy and potential dynamic polarization tests were performed to obtain corrosion parameters. Scanning electrochemical microscopy (SECM) was used to analyze the local electrochemical activity of the surface film. Atomic force microscope (AFM), Scanning electron microscope-Energy dispersive spectrometer and Fourier transform infrared spectroscopy were used to determine the surface morphology and chemical composition of the surface film. Findings Experimental results showed the presence of BSA in a certain concentration range (0 to 2.0 g/L) has a greater inhibitory effect on the corrosion of AZ31, however, the presence of high-concentration BSA (5.0 g/L) would sharply reduce the corrosion resistance. Originality/value When the concentration of BSA is less than 2.0 g/L, the corrosion resistance of AZ31 enhances with the concentration. The adsorption BSA layer will come into being a physical barrier to inhibit the corrosion process. However, high-concentration BSA (5.0 g/L) will chelate with dissolved metal ions (such as Mg and Ni) to form soluble complexes, which increases the roughness of the surface and accelerates the corrosion process.

Inhibition of proliferative growth in glioma cells by calmodulin antagonists

1986 ◽  
Vol 65 (1) ◽  
pp. 74-79 ◽  
Author(s):  
Nobuyuki Suzuki ◽  
Tetsuo Kanno ◽  
Yutaka Nagata ◽  
Taiji Kato
Keyword(s):  
Culture Medium ◽  
Deoxyribonucleic Acid ◽  
Control Level ◽  
Glioma Cells ◽  
Culture Conditions ◽  
Calmodulin Antagonists ◽  
High Concentration ◽  
Content Type ◽  
Chemically Induced ◽  
Proliferative Growth

✓ The effects of several calmodulin antagonists, such as N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide hydrochloride (W-7) and its dechlorinated structural analogue (W-5), on the growth and proliferation of cultured and transplanted glioma (GA-1, chemically induced from rat glioblasts) were evaluated. Under culture conditions, the concentration of W-7 necessary to exert 50% inhibition of GA-1 glioma cell growth was 50 µM. However, W-5, with a lower binding affinity to calmodulin than W-7, caused no definite inhibition of the proliferation of GA-1 cells in culture. When a low concentration of W-7 (12.5 µM) was added to the culture medium, deoxyribonucleic acid (DNA) synthesis in the GA-1 glioma cells was not markedly affected, whereas both ribonucleic acid (RNA) and protein syntheses were strongly suppressed on incubation for 24 hours. When a high concentration of W-7 (25.0 to 75.0 µM) was applied to the medium, synthesis of DNA, RNA, and protein was distinctly inhibited. When W-7 (50.0 µM) was added to the incubation medium, the calmodulin concentration in the cultured GA-1 was reduced to as much as half the control level within 2 hours, and thereafter remained at this level. Whereas control rats intraperitoneally transplanted with GA-1 cells could survive for 14 to 21 days, daily intraperitoneal injections of W-7 at concentrations of 1.0, 3.0, and 10.0 mg/kg body weight prolonged the survival span to between 21 and 26 days; this corresponded to an increased life span of about 40% compared to the controls.

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