Novel antimony phosphates with enlarged birefringence induced by lone pair cations.

Phosphates, whose obvious disadvantage is the relatively small birefringence, can be overcome by the introduction of post-transition metal cations containing stereochemically active lone-pair electrons. In this paper, two new compounds were successfully explored in the A-Sb-P-O system, i.e. Cs2Sb3O(PO4)3 (CsSbPO) and (NH4)2Sb4O2(H2O)(PO4)2[PO3(OH)]2 (NH4SbPOH). Transmission spectra show that CsSbPO has a surprising transmission range with a UV cutoff edge of 213 nm. First-principles calculations show that both compounds have a wide band gap (5.02 eV for CsSbPO and 5.30 eV for NH4SbPOH) and enlarged birefringence (Δn = 0.034@1064 nm for CsSbPO and Δn = 0.045@1064 nm for NH4SbPOH). The results of real-space atom-cutting investigations show that the distorted [SbOx] polyhedra originating from the asymmetric lone pair electrons give the main contribution to the total birefringence and overcome the disadvantage of small birefringence of phosphates but maintain wide transition windows.

Positive and Negative Contribution from Lead-Oxygen Groups and Halogen Atoms to Birefringence: A First Principles Investigation.

Oxyhalides, containing oxygen and halogen atoms and combining the advantages of oxides and halides in geometry and optical response, have great potential in optical materials. In this study, the electronic structures and the optical properties of the Pb3O2X2 (X = Cl, Br, I) compounds have been investigated using the first principles method. The results show that these compounds have birefringence at 0.076, 0.078, and 0.059 @ 1064 nm, respectively. And, the asymmetric stereochemical active lone pair electrons were found around lead atoms, which were confirmed by the projected density of states, the electronic localization functions, and the crystal orbitals. The contribution of atoms and polyhedra to birefringence was further evaluated using the Born effective charge. The results show that halogen atoms give negative contribution, and lead-oxygen polyhedra give positive contribution. The spin-orbit coupling effect is also investigated, and the downshift of the conduction band and variation in the valence band are found after relevant spin-orbit coupling (SOC), which leads to a reduction in the band gap and birefringence.

Synthesis, structures and properties of two new selenite optical materials: K2Zn3Se4O12 and K4Zn3V4Se2O19.

Two new selenites, K2Zn3Se4O12 (compound 1) and K4Zn3V4Se2O19 (compound 2), have been successfully synthesized by solid-state reactions in vacuum tubes. Compound 1 consists of a three-dimensional (3D) framework with [SeO3] triangular pyramids and [ZnO4] tetrahedra in the monoclinic space group P21/c (No. 14). Compound 1's cut-off edge is below 344 nm, based on its UV-Vis-NIR diffuse reflectance studies, and theoretical calculations indicate a birefringence of around 0.043 at 1064 nm. The two-dimensional layer of compound 2, in contrast, is made up of [SeO3] triangular pyramids, [ZnO4] tetrahedra, and [V4O13] tetrahedra. It crystallizes in the monoclinic space group C2/c (No. 15). Its UV-Vis-NIR diffuse reflectance studies demonstrate that the compound's cut-off edge is lower than 330 nm.

A Novel Ensemble Fault Diagnosis Model for Main Circulation Pumps of Converter Valves in VSC-HVDC Transmission Systems.

The intelligent fault diagnosis of main circulation pumps is crucial for ensuring their safe and stable operation. However, limited research has been conducted on this topic, and applying existing fault diagnosis methods designed for other equipment may not yield optimal results when directly used for main circulation pump fault diagnosis. To address this issue, we propose a novel ensemble fault diagnosis model for the main circulation pumps of converter valves in voltage source converter-based high voltage direct current transmission (VSG-HVDC) systems. The proposed model employs a set of base learners already able to achieve satisfying fault diagnosis performance and a weighting model based on deep reinforcement learning that synthesizes the outputs of these base learners and assigns different weights to obtain the final fault diagnosis results. The experimental results demonstrate that the proposed model outperforms alternative approaches, achieving an accuracy of 95.00% and an F1 score of 90.48%. Compared to the widely used long and short-term memory artificial neural network (LSTM), the proposed model exhibits improvements of 4.06% in accuracy and 7.85% in F1 score. Furthermore, it surpasses the latest existing ensemble model based on the improved sparrow algorithm, with enhancements of 1.56% in accuracy and 2.91% in F1 score. This work presents a data-driven tool with high accuracy for the fault diagnosis of main circulation pumps, which plays a critical role in maintaining the operational stability of VSG-HVDC systems and satisfying the unmanned requirements of offshore flexible platform cooling systems.

Water-Assisted Growth of Twisted 3R-Stacked MoSe2 Spirals and Its Dramatically Enhanced Second Harmonic Generations.

Enhanced second-harmonic generation (SHG) responses are reported in monolayer transition metal dichalcogenides (e.g., MX2 , M: Mo, W; X: S, Se) due to the broken symmetries. The 3R-like stacked MX2 spiral structures possessing the similar broken inversion symmetry should present dramatically enhanced SHG responses, thus providing great flexibility in designing miniaturized on-chip nonlinear optical devices. To achieve this, the first direct synthesis of twisted 3R-stacked chiral molybdenum diselenide (MoSe2 ) spiral structures with specific screw dislocations (SD) arms is reported, via designing a water-assisted chemical vapor transport (CVT) approach. The study also clarifies the formation mechanism of the MoSe2 spiral structures, by precisely regulating the precursor supply accompanying with multiscale characterizations. Significantly, an up to three orders of magnitude enhancement of the SHG responses in twisted 3R stacked MoSe2 spirals is demonstrated, which is proposed to arise from the synergistic effects of broken inversion symmetry, strong light-matter interaction, and band nesting effects. Briefly, the work provides an efficient synthetic route for achieving the 3R-stacked TMDCs spirals, which can serve as perfect platforms for promoting their applications in on-chip nonlinear optical devices.

Core root-associated prokaryotic community and its relationship to host traits across wheat varieties.

The root-associated microbiomes play important roles in plant growth. However, it is largely unknown how wheat variety evolutionary relatedness shapes each subcommunity in the root microbiome and, in turn, how these microbes affect wheat yield and quality. Here we studied the prokaryotic communities associated with the rhizosphere and root endosphere in 95 wheat varieties at regreening and heading stages. The results indicated that the less diverse but abundant core prokaryotic taxa occurred among all varieties. Among these core taxa, we identified 49 and 108 heritable amplicon sequence variants, whose variations in relative abundances across the root endosphere and rhizosphere samples were significantly affected by wheat variety. The significant correlations between phylogenetic distance of wheat varieties and prokaryotic community dissimilarity were only observed in non-core and abundant subcommunities in the endosphere samples. Again, wheat yield was only significantly associated with root endosphere microbiota at the heading stage. Additionally, wheat yield could be predicted using the total abundance of 94 prokaryotic taxa as an indicator. Our results demonstrated that the prokaryotic communities in the root endosphere had higher correlations with wheat yield and quality than those in the rhizosphere; thus, managing root endosphere microbiota, especially core taxa, through agronomic practices and crop breeding, is important for promoting wheat yield and quality.

Design and Analysis of a Cardioid Flow Tube Valveless Piezoelectric Pump for Medical Applications.

Piezoelectric pumps play an important role in modern medical technology. To improve the flow rate of valveless piezoelectric pumps with flow tube structures and promote the miniaturization and integration of their designs, a cardioid flow tube valveless piezoelectric pump (CFTVPP) is proposed in this study. The symmetric dual-bend tube design of CFTVPP holds great potential in applications such as fluid mixing and heat dissipation systems. The structure and working principle of the CFTVPP are analyzed, and flow resistance and velocity equations are established. Furthermore, the flow characteristics of the cardioid flow tube (CFT) are investigated through computational fluid dynamics, and the output performance of valveless piezoelectric pumps with different bend radii is studied. Experimental results demonstrate that CFTVPP exhibits the pumping effect, with a maximum vibration amplitude of 182.5 µm (at 22 Hz, 100 V) and a maximum output flow rate of 5.69 mL/min (at 25 Hz, 100 V). The results indicate that a smaller bend radius of the converging bend leads to a higher output flow rate, while the performance of valveless piezoelectric pumps with different diverging bends shows insignificant differences. The CFTVPP offers advantages such as a high output flow rate, low cost, small size for easy integration, and ease of manufacturing.

Improved Calculation Method of TAD for Intertrochanteric Fractures.

Purpose: To investigate the relative position of femur fixed screws using intramedullary systems for intertrochanteric fractures and to improve the accurate measurement method of the tip-to-apex distance (TAD) while providing a theoretical basis for the clinical treatment of such fractures. Methods: In the anteroposterior (AP) radiographs of the hip joint, the femoral neck axis through the femoral head geometry point was designated as the X-axis, while the line perpendicular to the X-axis passing through the femoral head geometry point was designated as the Y-axis. In the lateral radiographs of the hip joint, the line perpendicular to the X-axis passing through the femoral head geometry point was identified as the Z-axis. The head of the nail tip's location projected on the three axes was described as A AP, B in the AP radiographs; and A LAT, C in the lateral radiograph. The TAD was described as X AP and X LAT. The radius of the femoral head was D. All distance units were expressed in mm. Results: When the lateral projection angle was standardized, the A AP was equal to the A LAT, while the X AP 2=B 2+(D - A AP)2 and X LAT 2=C 2+(D - A LAT)2. When the lateral projection angle was not standardized, the value of C had no significant change; however, the (D - A LAT) value changed. Conclusions: The measurement value did not match the actual values of TAD when the lateral projection angle was not standardized, possibly leading to a misinterpretation during clinical work. The X LAT should be amended using the formula X LAT 2=C 2+(D - A AP)2.

Integrated organic and inorganic fertilization and reduced irrigation altered prokaryotic microbial community and diversity in different compartments of wheat root zone contributing to improved nitrogen uptake and wheat yield.

The effect of long-term water and integrated fertilization on prokaryotic microorganisms and their regulation for crop nutrient uptake remains unknown. Therefore, the impact of soil water and integrated fertilization after eight years on prokaryotic microbial communities in different compartments of root zone and their association with wheat nitrogen (N) absorption and yield were investigated. The results showed that compared with fertilization treatments (F), water regimes (W) more drastically modulated the prokaryotic microbial community structure and diversity in bulk soil, rhizosphere and endosphere. The increase of irrigation improved the prokaryotic diversity in the rhizosphere and endosphere while decreased the diversity in the bulk soil. Application of organic fertilizers significantly improved soil organic matter (SOM) and nutrient contents, increased rhizosphere and endophytic prokaryotic microbial diversity, and elevated the relative abundance of aerobic ammonia oxidation and nitrification-related functional microorganisms in rhizosphere and endosphere. Increasing irrigation elevated the relative abundance of functional microorganisms related to aerobic ammonia oxidation and nitrification in the rhizosphere and endosphere. Soil water content (SWC) and NH4+-N as well as NO3--N were key predictors of prokaryotic microbial community composition under W and F treatments, respectively. Appropriate application of irrigation and organic fertilizers increased the relative abundance of some beneficial bacteria such as Flavobacterium. Water and fertilization treatments regulated the prokaryotic microbial communities of bulk soil, rhizosphere and endosphere by altering SWC and SOM, and provided evidence for the modulation of prokaryotic microorganisms to promote nitrogen uptake and wheat yield under long-term irrigation and fertilization. Conclusively, the addition of organic manure (50 %) with inorganic fertilizers (50 %) and reduced amount of irrigation (pre-sowing and jointing-period irrigation) decreased the application amount of chemical fertilizers and water, while increased SOM and nutrient content, improved prokaryotic diversity, and changed prokaryotic microbial community structure in the wheat root zone, resulting in enhanced nutrient uptake and wheat yield.

Microwave-Assisted Coal-Derived Few-Layer Graphene as an Anode Material for Lithium-Ion Batteries.

A few-layer graphene (FLG) composite material was synthesized using a rich reservoir and low-cost coal under the microwave-assisted catalytic graphitization process. X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to evaluate the properties of the FLG sample. A well-developed microstructure and higher graphitization degree were achieved under microwave heating at 1300 °C using the S5% dual (Fe-Ni) catalyst for 20 min. In addition, the synthesized FLG sample encompassed the Raman spectrum 2D band at 2700 cm-1, which showed the existence of a few-layer graphene structure. The high-resolution TEM (transmission electron microscopy) image investigation of the S5% Fe-Ni sample confirmed that the fabricated FLG material consisted of two to seven graphitic layers, promoting the fast lithium-ion diffusion into the inner surface. The S5% Fe-Ni composite material delivered a high reversible capacity of 287.91 mAhg-1 at 0.1 C with a higher Coulombic efficiency of 99.9%. In contrast, the single catalyst of S10% Fe contained a reversible capacity of 260.13 mAhg-1 at 0.1 C with 97.96% Coulombic efficiency. Furthermore, the dual catalyst-loaded FLG sample demonstrated a high capacity-up to 95% of the initial reversible capacity retention-after 100 cycles. This study revealed the potential feasibility of producing FLG materials from bituminous coal used in a broad range as anode materials for lithium-ion batteries (LIBs).

Magnetic Field and Gravitational Waves from the First-Order Phase Transition.

We perform the three-dimensional lattice simulation of the magnetic field and gravitational wave productions from bubble collisions during the first-order electroweak phase transition. Except for the gravitational wave, the power-law spectrum of the magnetic field strength is numerically calculated for the first time, which is of a broken power-law spectrum: B_{ξ}∝f^{0.91} for the low-frequency region of ff_{⋆} in the thin-wall limit, with the peak frequency being f_{⋆}∼5 Hz at the phase transition temperature 100 GeV. When the hydrodynamics is taken into account, the generated magnetic field strength can reach B_{ξ}∼10^{-7} G at a correlation length ξ∼10^{-7} pc, which may seed the large scale magnetic fields. Our study shows that the measurements of cosmic magnetic field strength and gravitational waves are complementary to probe new physics admitting electroweak phase transition.

An Integral Recognition and Signaling for Electrochemical Assay of Protein Kinase Activity and Inhibitor by Reduced Graphene Oxide-Polydopamine-Silver Nanoparticle-Ti4+ Nanocomposite.

A novel electrochemical biosensing method for protein kinase (PKA) activity was demonstrated by using a reduced graphene oxide-polydopamine-silver nanoparticle-Ti4+ (rGO-PDA-AgNPs-Ti4+) nanocomposite. The obtained nanocomposite possessed an integral capability for phosphopeptide recognition and signal readout. The polydopamine modified reduced graphene oxide (rGO-PDA) was firstly prepared based on a self-polymerization method of dopamine. The silver ions were adsorbed onto polydopamine (PDA) layer and directly reduced into silver nanoparticles (AgNPs), which was used for electrochemical signal reporting. Then, the Ti4+ cations were attached onto the PDA layer for phosphopeptide recognition according to the strong coordination ability of PDA with Ti4+ and phosphate group. The prepared rGO-PDA-AgNPs-Ti4+ nanocomposites were characterized with different methods. The developed rGO-PDA-AgNPs-Ti4+ nanocomposites were then employed for electrochemical analysis of PKA-catalyzed kemptide phosphorylation. The sensitive detection toward PKA activity was realized with an experimental detection limit of about 0.01 U/mL. It may be also extended for the inhibitor evaluation. Thus, it provided a facile and sensitive means for electrochemical analysis of PKA activity and inhibitor screening.

Exonuclease III-Powered Self-Propelled DNA Machine for Distinctly Amplified Detection of Nucleic Acid and Protein.

Herein, a new exonuclease III (Exo III)-powered self-propelled DNA machine was developed for the cascade multilevel signal amplification of nucleic acid and nucleic acid-related analytes. It could be easily and homogeneously operated with the use of an integral DNA hybrid probe as the recognition, amplification, and signaling element, and the Exo III cleavage as a driving force. The DNA hybrid probe was obtained by annealing two hairpin-like DNAs. The target recognition with the 3'-protruding domain of the DNA hybrid probe triggered Exo III cleavage, accompanied by target recycling and alternate generation of a large amount of target substitute and analogy. Simultaneously, the cascade bidirectional Exo III cleavage toward the DNA hybrid probe by the generated target substitute and analogy contributed for the exponential signal amplification toward target recognition event. It could be also extended for the application in protein detection with the thrombin as a protein example by introducing an additional hairpin-like aptamer switch. The proposed Exo III-powered self-propelled DNA amplification strategy showed a linear detection range for target DNA from 0.5 fM to 1 pM and for thrombin from 5 fM to 10 pM. The low detection limit toward target DNA and thrombin could reach about 0.1 fM and 5 fM, respectively, which were superior to most of reported methods. It also exhibited an excellent selectivity toward target detection. Therefore, the developed sensing system exhibits a new, simple and powerful means for amplified detection of nucleic acid and nucleic acid-related analytes, and may hold great potentials in bioanalysis, disease diagnosis and biomedicine.

Oroxylin A Reduces Vasoconstriction in Rat Aortic Rings through Promoting NO Production and NOS Protein Expression via Estrogen Receptor Signal Pathway.

Oroxylin A, a flavonoid, is naturally produced in many medicinal plants. Our previous study identified it as a phytoestrogen. Based on this, the present study investigated its vasoconstriction reducing effects and whether the action was mediated by the estrogen receptor (ER) signal pathway. Long-term in vitro treatment with oroxylin A reduced Ach-induced vasorelaxation and NE-mediated or KCl-mediated contractile responses in rat aortic rings. These effects were interfered by an ER inhibitor ICI 182,780. Rat cardiac microvascular endothelial cells (CMECs) and aortic vascular smooth muscle cells (VSMCs) were used to study the possible underlying mechanisms. Oroxylin A activated the ER signal pathway. In CMECs, it increased NO production and eNOS protein expression. In VSMCs, it promoted NO production and iNOS protein expression. These effects were also inhibited by ICI 182,780. Besides, oroxylin A stimulated ERα and ERß protein expression in CMECs and VSMCs. All these findings suggest that the ER signal pathway takes part in the vasoconstriction reducing effects of oroxylin A.

Preparation of aminoalkyl-grafted bacterial cellulose membranes with improved antimicrobial properties for biomedical applications.

Bacterial cellulose (BC) membranes display special properties and structures, thus attracting much attention in application in the biomedical areas, for example, as implants for bone or cartilage tissue engineering, as substitutes for skin repairing, and as supports for controlled drug delivery. However, native BC lacks the activity to inhibit bacteria growth on its surface, which limits its applications in biomedical fields. There have been reports on chemical modification of BC membranes to endow them with antimicrobial properties needed for some special biomedical applications. In the present study, aminoalkyl-grafted BC membranes were prepared by alkoxysilane polycondensation using 3-aminopropyltriethoxysilane (APTES). The characterization for morphology and chemical composition showed that BC membranes were successfully grafted with aminoalkylsilane groups through covalent bonding. The surface morphology and roughness of the membranes changed after chemical grafting. Furthermore, after grafting with APTES, the membranes got less hydrophilic than native BC. The aminoalkyl-grafted BC membranes showed strong antibacterial properties against Staphylococcus aureus and Escherichia coli and moreover, they were nontoxic to normal human dermal fibroblasts. These results indicate that aminoalkyl-grafted BC membranes are potential to be used for biomedical applications.

Mindfulness interventions for rheumatoid arthritis: A systematic review and meta-analysis.

OBJECTIVES: To explore the effect of mindfulness interventions in improving outcomes for patients with rheumatoid arthritis. METHODS: Following the collective strategy of Cochrane Collaborative Group, the Cochrane Library, PubMed, EMBASE, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, and Wanfang Database were searched from the establishment of databases to September 2019. Reference lists were searched for additional studies. Risk of bias was assessed using Revman 5.3. Disagreement was resolved by discussion. RESULTS: A total of 6 RCTs were included, including 337 patients. The results showed that the improvement of pain intensity in mindfulness group after intervention was better than that in the control group, and the difference was significant [WMD = 0.65, 95% CI (-1.11, - 0.18), P = 0.006]. There were significant differences in depression between the two groups [SMD = 0.47, 95% CI (- 0.86, - 0.07), P = 0.02]. The results showed that there were significant differences in DSA28 between the two groups [WMD = -0.29,95% CI (- 0.38, - 0.19), P ＜0.00001]. The results showed that there were no significant differences in anxiety and CPR between the two groups. CONCLUSION: mindfulness interventions can significantly improve pain intensity, depression, and symptoms in patients with rheumatoid arthritis compared with conventional therapy. But the result still needs to be confirmed by more high-quality, large-sample randomized controlled trials.

Effect of cervus and cucumis polypeptide combined with zoledronic acid on bone metabolic biochemical markers in glucocorticoids - Induced osteoporosis patients.

OBJECTIVE: To investigate the effect of cervus and cucumis polypeptide combined with zoledronic acid on bone metabolic biochemical markers in glucocorticoids - induced osteoporosis patients. METHODS: A total of 100 patients with glucocorticoids - induced osteoporosis admitted to our hospital from January 2015 to June 2017 were enrolled in this study. Patients were divided into observation group and control group by random number table method, 50 cases in each group. Patients in the observation group were treated with deer melon polypeptide in combination with zoledronic acid, and patients in the control group were treated with zoledronic acid alone. The patients in both groups were treated for 2 months. The changes of bone mineral density (BMD) and biochemical markers of bone metabolism in lumbar vertebrae L1-4, left femoral neck and large trochanter were analyzed before and after treatment. RESULTS: The pre- BMD at lumbar spine L1-4, left femoral neck and great trochanter had no statistic difference (P > 0.05), the BMD at each sites improved after treatment, and the difference were statistical before and after treatment (P < 0.05). BMD at above sites of two groups after treatment had statistical difference (P < 0.05), and the BMD at lumbar spine L1-4, left femoral neck and great trochanter in the observation group was higher than that of the control group. There were no significant differences in PTH, 25-(OH)D3, TRACP, ß-CTX and BGP levels between the two groups before treatment (P > 0.05). The levels of 25-(OH)D3, TRACP, ß-CTX and BGP in the two groups were significantly improved after treatment (P < 0.05), and the levels of PTH, TRACP and ß-CTX in the observation group were significantly lower than those in the control group. The levels of 25-(OH) D3 and BGP were significantly higher than those of the control group (P < 0.05). CONCLUSION: The cervus and cucumis polypeptide combined with zoledronic acid can improve the BMD at lumbar spine L1-4, left femoral neck and great trochanter, and ameliorate the bone metabolic biochemical markers for patients with glucocorticoids - induced osteoporosis.

Dai-Zong-Fang, A Traditional Chinese Herbal Formula, Ameliorates Insulin Resistance in db/db Mice.

Intricate health problems, such as insulin resistance (IR) and its associated diseases, call for multi-targeted therapies with few side effects. Based on traditional Chinese medicine (TCM), Dai-Zong-Fang (DZF) is an herbal formula mainly composed of Rhizoma Coptidis (Huanglian) and Fructus Aurantii Immaturus (Zhishi), of which berberine and naringin are the main constituents. Though DZF has been clinically used for treatment of IR and metabolic syndrome for decades, its mechanism in vivo remains unknown. In the present study, we observed that both DZF and metformin, the first-line drug for type 2 diabetes, ameliorated insulin resistance with significant improvement of oral glucose tolerance test (OGTT) and homeostasis model assessment of IR (HOMA-IR) level in diabetic C57BL/Ksj-Lepr db-/- (db/db) mice. Low-density lipoprotein cholesterol (LDL-C) and fatty acids (FAs) also decreased in the blood. Higher dose of DZF (1 g·kg-1), but not metformin (0.25 g·kg-1), alleviated hepatic steatosis with reduced liver weight and hepatic lipid accumulation and provided protection from hepatic injury with lower alanine aminotransferase and aspartate aminotransferase and increased hepatic superoxide dismutase activity in db/db mice. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) showed a decrease in FA synthase gene (Fasn) and an increase in FA oxidation gene Ppara expression. Western blot demonstrated that both DZF and metformin activated 5' AMP-activated protein kinase (AMPK) but inhibited Notch intracellular domain (NICD) and Hairy/enhancer-of-split 1 (Hes1) of Notch signaling pathway in the liver. DZF also dramatically improved the ultrastructure of skeletal muscles, AMPK phosphorylation, and GLUT4 translocation. DZF also promoted FA transport and oxidation with Cd36 and Cpt1b up-regulation in the skeletal muscle. In conclusion, DZF improves insulin sensitivity by reducing hepatic lipids through AMPK activation and Notch signal pathway inhibition and enhancing energy metabolism in the skeletal muscle via AMPK. This study provides insights into the treatment of complex conditions, such as IR, where TCM herbal formulas exert multipronged effects through correlating pathways.

Quantitative and Localization Fault Diagnosis Method of Rolling Bearing Based on Quantitative Mapping Model.

Aiming to solve the problem of accurate diagnosis of the size and location of rolling bearing faults, a novel quantitative and localization fault diagnosis method of the rolling bearing is proposed based on the quantitative mapping model (QMM). The fault size and location of the rolling bearing affect the impulse type and the modulation degree of the vibration signal, which subsequently changes the complexity and randomness of the time-domain distribution of the vibration signal. According to the relationship between the multiscale permutation entropy (MPE) of the vibration signal and rolling bearing fault size, an average MPE (A-MPE) index is proposed to establish linear and nonlinear QMMs through the regression function. The proper QMM is selected through the error rate of fault size prediction to achieve a quantitative fault diagnosis of the rolling bearing. Due to the mathematical characteristics of the QMM, the localization fault diagnosis is realized. The multiscale morphological filtering (MMF) method is also introduced to extract the time-domain geometric feature of the fault bearing vibration signal and to improve the QMM accuracy of the fault size prediction. The results show that the QMM has a great effect on the quantitative fault size prediction and localization diagnosis of the rolling bearing.