Rolling bearing fault diagnosis using improved LCD-TEO and softmax classifier

A novel rolling bearing fault diagnosis method based on improved local characteristic-scale decomposition (LCD), Teager energy operator (TEO) and softmax classifier is proposed in this paper. First, vibration signals are decomposed into several intrinsic scale components (ISCs) by using improved LCD; second, TEO and fast Fourier transform (FFT) are respectively used to extract instantaneous amplitude (IA) and frequency spectra of ISC1s, and then FFT is again employed to obtain spectra of IA; third, energy ratio of the resonant frequency band against the total, frequency entropy (FE) in the spectra of ISC1s and several amplitude ratios in the frequency spectra of demodulated ISC1s are extracted as fault feature vectors, and principal components analysis (PCA) is applied for dimensionality reduction; finally, these feature vectors are taken as inputs to train and test softmax classifier. As a new non-stationary signal analysis tool, LCD can decompose adaptively a signal into series of ISCs in different scales and give good results in situations where other methods failed. However, there are two main issues in this method, end effect and mode mixing, possibly leading to unexpected results. In this paper, a slope-based method and noise assisted analysis are applied to restrain the problems respectively. Experimental results show the proposed method performs effectively for bearing fault diagnosis

Experimental study on the seismic behavior of coupled shear wall with concealed partitioned steel plates

To study the seismic behavior and post-earthquake repairability of coupled shear wall with concrete filled steel tube (CFST) frame and concealed partitioned steel plates (SPs), three 1/5 scaled coupled shear wall specimens were designed with different type of CFST column or core structure. Low-cycle reversed loading was adopted in the test. The test contained two stages. Load-carrying capacity, energy dissipation, ductility, stiffness and failure characteristic of the specimens were compared in pre-repair stages and post-repair stages. The conclusions are drawn that the core structure shows a good ductile yielding mechanism. The cross-section type of frame has an obvious effect on the seismic behavior of shear wall. After damage and strengthening, the new coupled shear wall still has enough seismic capacity and good energy dissipation capacity, and it is easy to be repaired after earthquake. Finite element analysis software ABAQUS has been used to simulate the behavior of coupled shear wall. Ultimate strength is obtained with the vibration of thickness of SPs

MSGNet: Learning Multi-Scale Inter-Series Correlations for Multivariate Time Series Forecasting

Multivariate time series forecasting poses an ongoing challenge across various disciplines. Time series data often exhibit diverse intra-series and inter-series correlations, contributing to intricate and interwoven dependencies that have been the focus of numerous studies. Nevertheless, a significant research gap remains in comprehending the varying inter-series correlations across different time scales among multiple time series, an area that has received limited attention in the literature. To bridge this gap, this paper introduces MSGNet, an advanced deep learning model designed to capture the varying inter-series correlations across multiple time scales using frequency domain analysis and adaptive graph convolution. By leveraging frequency domain analysis, MSGNet effectively extracts salient periodic patterns and decomposes the time series into distinct time scales. The model incorporates a self-attention mechanism to capture intra-series dependencies, while introducing an adaptive mixhop graph convolution layer to autonomously learn diverse inter-series correlations within each time scale. Extensive experiments are conducted on several real-world datasets to showcase the effectiveness of MSGNet. Furthermore, MSGNet possesses the ability to automatically learn explainable multi-scale inter-series correlations, exhibiting strong generalization capabilities even when applied to out-of-distribution samples.Comment: 13 pages, 12 figure

Effects of temperature on photosynthetic performance and nitrate reductase activity in vivo assay in Gracilariopsis lemaneiformis (Rhodophyta)

Gracilariopsis lemaneiformis is an economically-valued species and widely cultured in China at present. After being acclimated to different growth temperatures (15, 20, 25, and 30 degrees C) for 7 days, the relative growth rate (RGR), nitrate reductase activity, soluble protein content and chlorophyll a fluorescence of G. lemaneiformis were examined. Results show that RGR was markedly affected by temperature especially at 20 degrees C at which G. lemaneiformis exhibited the highest effective quantum yield of PSII [Y(II)] and light-saturated electron transport rate (ETRmax), but the lowest non-photochemical quenching. Irrespective of growth temperature, the nitrate reductase activity increased with the incubation temperature from 15 to 30 degrees C. In addition, the greatest nitrate reductase activity was found in the thalli grown at 20 degrees C. The value of temperature coefficient Q10 of alga cultured in 15 degrees C was the greatest among those of other temperatures tested. Results indicate that the optimum temperature for nitrate reductase synthesis was relatively lower than that for nitrate reductase activity, and the relationship among growth, photosynthesis, and nitrate reductase activity showed that the optimum temperature for activity of nitrate reductase in vivo assay should be the same to the optimal growth temperature

Seismic behaviour of composite shear wall with steel reinforced concrete frame and embedded perforated-steel plate

U radu se ispituje pet uzoraka posmičnih stijena raznih dimenzijskih i konstrukcijskih karakteristika kako bi se istražilo seizmičko ponašanje spregnute posmične stijene s armiranobetonskim okvirom ojačanim čelikom i ugrađenom perforiranom čeličnom pločom. Osim toga, niskociklično opterećenje se nanosi na uzorke s koeficijentom posmične zone od 1,5. Eksperimentalni podaci koriste se za analizu nosivosti, krutosti, duktilnosti, histerezne energije i karakteristika otkazivanja spomenutih uzoraka. Rezultati pokazuju da se spregnuta posmična stijena s armiranobetonskim okvirom ojačanim čelikom i ugrađenom čeličnom pločom odlikuje većom nosivošću, boljom duktilnošću, sporijim padom krutosti te većom sposobnošću rasapa energije u usporedbi s običnim armiranobetonskim posmičnim zidom. Osim toga, primjenom ugrađenih čeličnih ploča odgovarajuće debljine poboljšava se i seizmičko ponašanje spregnutih posmičnih stijena. Analizom čeličnih ploča iste debljine utvrđeno je da se uzorci s čeličnim vezicama seizmički bolje ponašaju od uzoraka sa zavarenim svornjacima. U završnom je dijelu razvijen računalni model za izračunavanje nosivosti CSW-a. Usporedba pokazuje dobru podudarnost rezultata proračuna i rezultata dobivenih mjerenjem.Experiments are conducted on five shear wall specimens of varying design and structural measures in order to investigate seismic behaviour of a composite shear wall with the steel-reinforced concrete frame and an embedded perforated-steel plate. In addition, low-cyclic load is applied on test specimens that have a shear span ratio of 1.5. Using the experimental data, the bearing capacity, stiffness, ductility, hysteretic energy, and failure characteristics of five specimens are analysed. The results show that the composite shear wall (CSW) with the steel reinforced concrete frame (SRCF) and embedded steel plate (ESP) has higher bearing capacity, better ductility, slower degradation of stiffness, and higher energy dissipation capacity, as compared to an ordinary reinforced concrete shear wall. Moreover, its seismic behaviour can be improved by using the ESP of an appropriate thickness. For the ESPs of identical thickness, the results show that the specimen that uses steel ties exhibits better seismic behaviour than those using welding studs. Finally, a computing model that can calculate the bearing capacity of the CSWs is developed. A comparison of calculated and measured results shows that the results are close to each other