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"Lu, Ze"
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A nonlinear vibration isolator supported on a flexible plate: analysis and experiment
To address low-frequency vibration isolation, an issue that engineers often face, this paper first studies the nonlinear energy transfer of a flexible plate, with arbitrary boundary, with the coupling of high-static-low-dynamic-stiffness (HSLDS) isolator. The nonlinear coupled dynamic equation was derived via the Lagrange method, and the improved Fourier series and Rayleigh–Ritz methods provide modal coefficients of the arbitrary boundary flexible plate with nonlinear vibration isolators. The Galerkin and harmonic balance methods approximate the frequency response functions of power flow for the coupled system. The numerical method, via direct integration of the dynamic equation, validates the analytical results of the frequency response functions. In addition, the finite element simulation, used here, validates the analytical results of the mode shapes for flexible plate. The experiment is carried out to validate the isolation performance of the nonlinear vibrator supported on a flexible plate. On these bases, increasing damping and controlling HSLDS can improve the low-frequency isolation efficiency, and nonlinear jumping-phenomena could disappear over a low-frequency range (either frequency overlap or frequency jump). Hence, a properly configured flexible plate could improve the bearing capacity and low-frequency isolation efficiency while avoiding frequency mistune. An explanation for these is offered in the article.
Journal Article
Ocean wave energy harvesting with high energy density and self-powered monitoring system
Constructing a ocean Internet of Things requires an essential ocean environment monitoring system. However, the widely distributed existing ocean monitoring sensors make it impractical to provide power and transmit monitored information through cables. Therefore, ocean environment monitoring systems particularly need a continuous power supply and wireless transmission capability for monitoring information. Consequently, a high-strength, environmentally multi-compatible, floatable metamaterial energy harvesting device has been designed through integrated dynamic matching optimization of materials, structures, and signal transmission. The self-powered monitoring system breaks through the limitations of cables and batteries in the ultra-low-frequency wave environment (1 to 2 Hz), enabling real-time monitoring of various ocean parameters and wirelessly transmitting the data to the cloud for post-processing. Compared with solar and wind energy in the ocean environment, the energy harvesting device based on the defective state characteristics of metamaterials achieves a high-energy density (99 W/m
3
). For the first time, a stable power supply for the monitoring system has been realized in various weather conditions (24 h).
Point-defect metamaterials have the property of concentrating vibration energy at the defect location. We design an environmental monitoring node based on this property, which can efficiently convert wave kinetic energy into electrical energy for real-time monitoring of the ocean environment.
Journal Article
Visual attention network
While originally designed for natural language processing tasks, the self-attention mechanism has recently taken various computer vision areas by storm. However, the 2D nature of images brings three challenges for applying self-attention in computer vision: (1) treating images as 1D sequences neglects their 2D structures; (2) the quadratic complexity is too expensive for high-resolution images; (3) it only captures spatial adaptability but ignores channel adaptability. In this paper, we propose a novel linear attention named large kernel attention (LKA) to enable self-adaptive and long-range correlations in self-attention while avoiding its shortcomings. Furthermore, we present a neural network based on LKA, namely Visual Attention Network (VAN). While extremely simple, VAN achieves comparable results with similar size convolutional neural networks (CNNs) and vision transformers (ViTs) in various tasks, including image classification, object detection, semantic segmentation, panoptic segmentation, pose estimation, etc. For example, VAN-B6 achieves 87.8% accuracy on ImageNet benchmark, and sets new state-of-the-art performance (58.2 PQ) for panoptic segmentation. Besides, VAN-B2 surpasses Swin-T 4 mIoU (50.1 vs. 46.1) for semantic segmentation on ADE20K benchmark, 2.6 AP (48.8 vs. 46.2) for object detection on COCO dataset. It provides a novel method and a simple yet strong baseline for the community. The code is available at
https://github.com/Visual-Attention-Network
.
Journal Article
Constituents, Pharmacokinetics, and Pharmacology of Gegen-Qinlian Decoction
Gegen-Qinlian decoction (GQD) is a classic traditional Chinese medicine (TCM) formula. It is composed of four TCMs, including Puerariae Lobatae Radix , Scutellariae Radix , Coptidis Rhizoma , and Glycyrrhizae Radix et Rhizoma Praeparata cum Melle . GQD is traditionally and clinically used to treat both the “external and internal symptoms” of diarrhea with fever. In this review, key words related to GQD were searched in the Web of Science, PubMed, China National Knowledge Infrastructure (CNKI), and other databases. Literature published mainly from 2000 to 2020 was screened and summarized. The main constituents of GQD could be classified into eight groups according to their structures: flavonoid C -glycosides, flavonoid O -glucuronides, benzylisoquinoline alkaloids, free flavonoids, flavonoid O -glycosides, coumarins, triterpenoid saponins, and others. The parent constituents of GQD that enter circulation mainly include puerarin and daidzein from Puerariae Lobatae Radix , baicalin and wogonoside from Scutellariae Radix , berberine and magnoflorine from Coptidis Rhizoma , as well as glycyrrhetinic acid and glycyrrhizic acid from Glycyrrhizae Radix et Rhizoma Praeparata cum Melle . GQD is effective against inflammatory intestinal diseases, including diarrhea, ulcerative colitis, and intestinal adverse reactions caused by chemotherapeutic agents. Moreover, GQD has significant effects on metabolic diseases, such as nonalcoholic fatty liver and type 2 diabetes. Furthermore, GQD can be used to treat lung injury. In brief, the main constituents, the pharmacokinetic and pharmacological profiles of GQD were summarized in this review. In addition, several issues of GQD including effective constituents, interactions between the constituents, pharmacokinetics, interaction potential with drugs and pharmacological effects were discussed, and related future researches were prospected in this review.
Journal Article
Nonlinear vibration effects on the fatigue life of fluid-conveying pipes composed of axially functionally graded materials
Fatigue is inevitable in pipes conveying fluid due to unwanted vibration. Internal resonance occurs in such pipes due to pre-pressure. For the first time, the effects of vibration on the fatigue of fluid-conveying pipes are investigated in this paper. The influences of the internal resonance and the axially functionally graded materials on the fatigue of the pipes are analyzed, aiming at improving mechanical properties and increasing fatigue life. The Galerkin method and the direct multi-scale method are used to construct the solvability condition for the primary resonance and 1:3 internal resonance. Approximate analytical solutions are derived for presenting the nonlinear dynamics of the pipes. The tensile, bending, and resultant stress distribution of the axially functionally graded pipe in internal resonance is determined. The results of the fatigue analysis demonstrate that internal resonance can shorten the fatigue life of axially functionally graded pipes. Reducing the distribution coefficient of functionally graded pipe is beneficial for reducing the resonance response and maximum stress of the pipe conveying fluid. The numerical integration results support the analytical results.
Journal Article
Increased risk of chronic kidney disease in uric acid stone formers with high neutrophil-to-lymphocyte ratio
Urolithiasis is associated with an increased risk of chronic kidney disease (CKD), irrespective of stone compositions. Chronic inflammation is an important factor for CKD progression. Neutrophil-to-lymphocyte ratio (NLR) has been recognized as a reliable biomarker of inflammation, yet its use in predicting renal deterioration in patients with urolithiasis remains limited. We aimed to explore whether the combination of stone composition and NLR could be useful as a predictor for CKD risk. A total of 336 stone formers with at least one stone submission for analysis were enrolled in the retrospective study. Stones were classified into uric acid and calcium groups. Renal functions were assessed at least one month after stone treatment. Uric acid stone formers had significantly lower estimated glomerular filtration rate (eGFR) compared with calcium stone formers (
p
< 0.001). NLR was significantly higher in uric acid stone formers (
p
= 0.005), and a significantly negative correlation (
p
< 0.001) between NLR and eGFR had been observed only in uric acid stone group. Univariate and multivariate logistic regression analyses showed that higher proportion of uric acid stone composition and higher NLR were both significantly associated with CKD risks. A nomogram integrating independent predictors was generated for CKD prediction, yielding an AUC of 0.811 (0.764–0.858). In conclusion, our study demonstrated that stone formers with higher proportion of uric acid composition and higher NLR levels were associated with higher CKD risk.
Journal Article
Plate theory based modeling and analysis of nonlinear piezoelectric composite circular plate energy harvesters
A piezoelectric composite circular plate energy harvester is modeled and analyzed based on a nonlinear plate theory. The harvester consists of a bimorph piezoelectric circular plate and a rigid body. The nonlinear electromechanical coupling equations are derived from the Hamilton principle and the von Karman plate theory with the account for the structural weight. The equations are discretized via the Galerkin truncation method (GTM) for the vibration around the equilibrium configuration. The discrete equations are approximately solved via the harmonic balance method (HBM) with the convergence considerations. Moreover, the solutions are validated by the Runge–Kutta method (RKM) and the finite element simulations. The account for the structural weight leads to the asymmetricity in the relation of the restoring force and the deformation. The amplitude-frequency response curves display a typical hardened nonlinear behavior in the first-order vibration mode and a linear behavior in the second-order vibration mode. Parametric studies demonstrate the effects of the rigid body mass, the external excitation amplitude, the load resistance, and the piezoelectric composite plate size on harvesting the performance.
Journal Article
A dynamic modeling approach for six-degree-of-freedom control of maglev planar motors with reference trajectory tracking
Magnetic levitation planar motors (MLPMs) exhibit significant potential in high-precision positioning applications, however the 6-degree-of-freedom (6-DOF) control performance is inherently limited by complex nonlinear dynamics. This paper proposes a 6-DOF dynamic modeling methodology for maglev planar motors based on reference trajectory tracking. The proposed approach synergistically combines magnetic flux analytical linearization with electromagnetic coupling field decoupling, establishing a unified control framework that comprehensively addresses kinematic nonlinearities and full-DOF coupling effects. By employing harmonic spectral analysis and a dual-reference coordinate transformation architecture, the method enables precise analytical derivation of electromagnetic force/torque distributions within the operational workspace. Numerical simulations validate the improved modeling accuracy, demonstrating a 5.3-fold reduction in wrench prediction errors under large yaw rotations compared to conventional methods. Finally, an experimental rig of the planar motor is manufactured to validate the theoretical trajectory tracking method. The experimental results confirm the robustness of the methodology in achieving high-precision motion control and long-stroke trajectory tracking, offering valuable insights for bridging theoretical modeling and industrial implementation of maglev planar motor systems.
Journal Article
A Double-Activity (Green Algae Toxicity and Bacterial Genotoxicity) 3D-QSAR Model Based on the Comprehensive Index Method and Its Application in Fluoroquinolones’ Modification
The comparative molecular similarity index analysis (CoMSIA) model of double-activity quinolones targeting green algae toxicity and bacterial genotoxicity (8:2) was constructed in this paper on the basis of the comprehensive index method. The contour maps of the model were analyzed for molecular modifications with high toxicities. In the CoMSIA model, the optimum number of components n was 7, the cross-validated q2 value was 0.58 (>0.5), the standard deviation standard error of estimate (SEE) was 0.02 (<0.95), F was 1265.33, and the non-cross-validated R2 value was 1 (>0.9), indicating that the model had a good fit and predicting ability. The scrambling stability test parameters Q2, cross-validated standard error of prediction (cSDEP), and dq2/dr2yy were 0.54, 0.25, and 0.8 (<1.2), respectively, indicating that the model had good stability. The external verification coefficient r2pred was 0.73 (>0.6), and standard error of prediction (SEP) was 0.17, indicating that the model had a good external prediction ability. The contribution rates of the steric fields, electrostatic fields, hydrophobic fields, hydrogen bond donor, and acceptor fields were 10.9%, 19.8%, 32.7%, 13.8%, and 22.8%, respectively. Large volume groups were selected for modification of ciprofloxacin (CIP), and the derivatives with increased double-activity characterization values were screened; the increase ratio ranged from 12.31–19.09%. The frequency of derivatives were positive and total energy, bioaccumulation, and environmental persistence was reduced, indicating that the CIP derivatives had good environmental stability and friendliness. Predicted values and CoMSIA model constructed of single activities showed that the CoMSIA model of double activities had accuracy and reliability. In addition, the total scores of the derivatives docking with the D1 protein, ferredoxin-NADP (H) reductases (FNRs), and DNA gyrase increased, indicating that derivatives can be toxic to green algae by affecting the photosynthesis of green algae. The mechanism behind the bactericidal effect was also explained from a molecular perspective.
Journal Article