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Although pure time-domain features have the advantages of fast extraction speed and clear physical meaning, the diagnostic accuracy is slightly inferior to other methods. To solve this problem, a new bearing feature extraction method based on the time subsequence (BOTS) is proposed, which combines word package model and time subsequence. First, the sliding window is used to slide in the vibration signal to obtain multiple continuous and non-stationary time series, which are regarded as a document. For each time series, multiple continuous subsequences of fixed length are randomly intercepted to obtain the time-domain or frequency-domain characteristics of subsequences. Then, the random forest algorithm is used to count the class votes of all subsequences in each time series, and a dictionary is constructed based on the class votes. Finally, the dictionary is used as a new feature and input into the random forest classifier for training and learning. A variety of experiments are carried out using the bearing data provided by the SQI-MFS experimental platform of Wuxi Innovation Center of SIEMENS China Research Institute, Southeast University and Institute of Mechanical Failure Prevention Technology. The experiments show that the features extracted by BOTS+ wavelet packet energy method have higher recognition.

Graph embedding is a widely used method for dimensionality reduction due to its computational effectiveness.The computational complexity of graph embedding method to construct traditional K-Nearest Neighbors (K-NN) graph is at least O(n2d), where n and d represents the sample size and dimensions respectively.The construction of K-NN graphs is very time-consuming since the computational complexity is proportional to the square of the number of samples in the case of a large amount of data, which will limit the application of graph embedding algorithms on large-scale data sets.To address this problem, a fast unsupervised graph embedding based on anchors (FUGE) method is proposed in this paper.FUGE first selects anchors (representative points) from the data, then constructs a similarity graph between the data and anchors, and finally performs graph embedding analysis.Since the number of anchors is much smaller than the number of data, the proposed method can effectively reduce the computational complexity of the process of graph construction.Different from using the kernel function to construct the similarity graph, FUGE directly learns the data point-anchor similarity graph by the neighbor information of the data, which further accelerates the process of graph construction.The overall computational complexity of FUGE is O(nd2+nmd), where m is the number of anchors.Extensive experiments on real-world benchmark data sets show the effectiveness and efficiency of the proposed method.

The accumulation of sand induced by wind poses a significant challenge to the safety and maintenance of railways in arid and desert regions. Accurate calculation and prediction of sand accumulation are crucial for ensuring continuous railway operation. This research is centered on the region significantly impacted by sand accumulation along the Ganquan Railway. Wind speed, wind direction, and sand carrying capacity data near this section were monitored. Using the collected wind speed, wind direction, and wind-sand flow density data, numerical simulations were conducted using the Computational Fluid Dynamics (CFD) method to predict the amount of sand accumulation within the sand mitigation measures of the Ganquan Railway. Monitoring results indicate that the dominant wind direction in spring and summer is due west, while in autumn and winter it is southwest, with an average wind speed of 12 m/s. A positive correlation was observed between wind-sand flow density and wind speed. The wind-sand flow density above 2 m was nearly zero, indicating that the wind-sand flow structure is concentrated within 2 m from the ground, with an average wind-sand flow density of 3.50x10-5 kg/m3. Through numerical simulation, the characteristics of the wind field and sand accumulation distribution within the calculation domain were determined. A relationship equation between sand accumulation mass and width over time was derived. Initially, the sand accumulation width increases uniformly and then stabilizes, while the sand accumulation mass rises uniformly to a plateau before in-creasing rapidly. From these findings, the optimal period for sand removal was identified as between 350 and 450 days after the sand mitigation measures are put into operation. [ABSTRACT FROM AUTHOR]

In this concept, we showcase the upsurge in the studies of dynamic ultralong room‐temperature phosphorescence (RTP) materials containing inorganic and/or organic components as versatile photo‐responsive platforms. The goal is to provide a comprehensive analysis of photo‐controllable RTP, and meanwhile delve into the underlying RTP properties of various classes of photochromic materials including metal‐organic complexes, organic‐inorganic co‐crystals, purely organic small molecules and organic polymers. In particular, the design principles governing the integration of the photochromic and RTP moieties within a single material system, and the tuning of dynamic RTP in response to light are emphasized. As such, this concept sheds light on the challenges and opportunities of using these tunable RTP materials for potential applications in optoelectronics, particularly highlighting their use of reversible information encryption, erasable light printing and rewritable smart paper. [ABSTRACT FROM AUTHOR]

Room temperature phosphorescence (RTP) with long afterglow from molecular crystals has been the subject of growing interest for researchers over the last decade due to its potential applications in human lives. Highly efficient RTP materials in small low-molecular-weight systems are still limited owing to the singlet state (S0) to triplet state (T1) spin forbidden process and weak spin–orbital coupling. The crystal engineering strategy has been proven useful for the development of long persistent luminescent (LPL) materials. Here we developed two hydrated polymorphic co-crystals that were "engineered" with tautomeric 2-amino-6-methyl-1,4-dihydropyrimidin-4-one (AHMP) and saccharin. Both the polymorphs exhibit bright ultralong phosphorescence with AS-I showing longer RTP lifetime. The different cyan and yellow afterglow colors of AS-I and AS-II indicate that their photoluminescence properties can be highly tuned through changes in both their chemical structure and solid state packing. This is interpreted in terms of different singlet–triplet intersystem crossing (ISC) processes between the S1 and the low-lying triplet states in the two forms. Hole–electron analysis of these two forms suggests that the spin–vibronic coupling between the local and charge transfer excited states contributes vitally to their persistent luminescence. The significance for the photoluminescence of AS-I and AS-II is the strong spin-orbital coupling (SOC) between the singlet and triplet states of AHMP and saccharin molecules, in which AS-I is more favorable by up to an order of magnitude than AS-II. Therefore, this research leads to appreciation that stacking state regulation in polymorphic co-crystals is promising to achieve ultralong phosphorescence for small molecules. [ABSTRACT FROM AUTHOR]

The oxygen evolution kinetics of industrial copper electrodeposition is slow, resulting in low electrocatalytic activity and high energy consumption. In this work, a quaternary composite of carbon coated active particles containing Mn, Co and Ce were prepared (Mn-Co3O4/CeO2@C), and Ti/Sb-SnO2/PbO2 electrode doped with these active particles was prepared by co-electrodeposition. The microstructure and chemical composition of the electrode was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractometry (XRD). Linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and Tafel polarization curve (Tafel) were used to study the electrochemical properties of anode materials. The results showed that the doping of Mn-Co3O4/CeO2@C active particles promoted the crystal transition of PbO2, decreased the average grain size, and the doping of Ce increases the average valence state of Co. The modified titanium electrode showed excellent catalytic activity of the oxygen evolution reaction (OER) characteristics. The overpotential of the doped Ti/Sb-SnO2/PbO2 anode was only 453 mV when the current density was 20 mA cm−2 in 0.5 M H2SO4 solution, which is 508 mV lower than that of the undoped Ti/Sb-SnO2/PbO2 anode. In simulated copper electro-deposition experiments, the cell voltage was reduced by about 400 mV, compared to the undoped Ti/Sb-SnO2/PbO2 electrode. [ABSTRACT FROM AUTHOR]

Due to the lack of corresponding magmatic records, the timing of the opening of the Yarlung–Tsangpo Neo‐Tethyan Ocean remains controversial. The Middle Permian Luerma igneous complex, which is situated in the western Gangdese magmatic belt of the southern Lhasa subterrane, western Tibet, can be divided into four or more rock types, including foid gabbro, amphibole gabbro, monzogabbro, and pyroxene‐bearing monzodiorite. Through zircon U–Pb dating using laser ablation–inductively coupled plasma–mass spectrometry, the age of the Luerma igneous complex is determined to be ~261 Ma. The complex is rich in titanium, iron, magnesium, and total alkalis, with medium to high levels of calcium, potassium and aluminium, as well as low levels of silicon. Therefore, it is classified as a shoshonite–latite rock series. The complex is relatively enriched in light rare earth elements and high‐field‐strength elements, without obvious Eu and Ce anomalies. These rocks exhibit relatively low (87Sr/86Sr)i values, high εNd(t) values, and high εHf(t) values. The geochemical and isotopic characteristics indicate that the magmas are derived from partial melting of the upper mantle in an intraplate tectonic environment. The new data presented here provide supplementary evidence for the initial rifting of the Lhasa terrane from the northern margin of Gondwana during the Middle Permian. These data also confirm that the opening of the Yarlung–Tsangpo Neo‐Tethyan Ocean occurred in the Middle Permian. [ABSTRACT FROM AUTHOR]