The thickness error of the thin strip determines the product quality of thin strip. As a typical dynamic continuous non-Gaussian process, the thin strip has complex irregular noise, and the general ...prediction method will produce significant errors. According to the rolling characteristics of thin strip, a radial basis function neural network based on variational Bayesian Gaussian mixture clustering algorithm (VBGM-RBF) is proposed to predict the thickness of cold-rolled thin strip. The production data of 160000 sets of cold-rolled strips are obtained by removing outliers according to the data characteristics by the combination of manual selection, isolated forest algorithm, and Bessel formula. Considering the mean square error (MSE) and correlation coefficient (R
2
), the parameter settings of RBF neural network and optimization algorithm are studied to obtain the optimal model. This paper compares the prediction performance of RBF neural network optimized by different clustering algorithms, tests the prediction error of adding noise samples in the neural network, and analyzes the influencing factors of strip thickness. The results show that VBGM-RBF has the highest prediction accuracy compared with some traditional RBF neural networks. The MSE of the VBGM-RBF model is
0.5053
μ
m
2
, the maximum error percentage (MPE) is 1.842
%
, and the absolute error of 99.40
%
of the predicted data is less than 2
μ
m. In the analysis of the factors affecting the thickness, the model is consistent with the physical law of thin strip rolling. VBGM-RBF model has strong learning ability and generalization performance and can be well-applied to the production of thin strip steel.
Direct-acting relief valve is widely applied in pumps for control of pump pressure; when it is applied by underwater equipment, its dynamic stability is challenged by the varied hydraulic pressure ...due to the variation of its underwater penetration; specifically, sudden jumps of pump pressure can be triggered, which brings harmful influence on the normal working condition of underwater equipment. In order to fully understand this phenomenon, a two-degree-of-freedom fluid–structure coupling model is developed by considering both the axial and longitudinal vibro-impacts between the valve element and the valve seat, whose external excitation comes from the flowing fuel which has been accelerated to a high speed in the narrow channel of relief valve. Based on the developed mathematical model, the predicted errors about the water depth for appearance of the sudden jump of pressure are verified within 5% when compared with the corresponding experimental results. Moreover, the axial vibro-impact oscillation of the valve element is demonstrated as the origin of such drastic fluctuation of pump pressure. In order to further control the sudden jumps of pressure, parameter optimization with reliability analysis is carried out via an optimization closed loop which consists of design of experiment algorithm, Monte Carlo algorithm and six sigma algorithm. Based on the optimized combination of parameters, the pressure stability of the direct-acting relief valve is secured within its working water depth as 0 m, 300 m, and the differential pressure at the valve port remains a linear variation without sudden jump, and the maximal change of the differential pressure is around 3.6 MPa, which is determined by the variation of water depth.
Graphic abstract
Until recently, the molecular pathogenesis of preeclampsia (PE) remained largely unknown. Reports have shown that circulating microRNAs (miRNAs) are promising novel biomarkers for cancer, pregnancy, ...tissue injury, and other conditions. The objective of this study was to identify differentially expressed miRNAs in plasma from severe preeclamptic pregnancies compared with plasma from normal pregnancies. By mature miRNA microarray analysis, 15 miRNAs, including 13 up- and two downregulated miRNAs, were screened to be differentially expressed in plasma from women with severe PE (sPE). Seven miRNAs, namely miR-24, miR-26a, miR-103, miR-130b, miR-181a, miR-342-3p, and miR-574-5p, were validated to be elevated in plasma from severe preeclamptic pregnancies by real-time quantitative stem-loop RT-PCR analysis. Gene ontology and pathway enrichment analyses revealed that these miRNAs were involved in specific biological process categories (including regulation of metabolic processes, regulation of transcription, and cell cycle) and signaling pathways (including the MAP kinase signaling pathway, the transforming growth factor-β signaling pathway, and pathways in cancer metastasis). This study presents, for the first time, the differential expression profile of circulating miRNAs in sPE patients. The seven elevated circulating miRNAs may play critical roles in the pathogenesis of sPE, and one or more of them may become potential markers for diagnosing sPE.
In this study, we investigated the influence of β-asarone, the major ingredient of Acorus tatarinowii Schott, on depressive-like behavior induced by the chronic unpredictable mild stresses (CUMS) ...paradigm and to clarify the underlying mechanisms. The results show that β-asarone treatment partially reversed the CUMS-induced depression-like behaviors in both the forced swim and sucrose preference tests. The behavioral effects were associated with increased hippocampal neurogenesis indicated by bromodeoxyuridine (BrdU) immunoreactivity. β-Asarone treatment significantly increased the expression of brain-derived neurotrophic factor (BDNF) at levels of transcription and translation. Moreover, CUMS caused significant reduction in ERK1/2 and CREB phosphorylation, both of which were partially attenuated by β-asarone administration. It is important to note that β-asarone treatment had no effect on total levels or phosphorylation state of any of the proteins examined in ERK1/2-CREB pathway in no stress rats, suggesting that β-asarone acts in a stress-dependent manner to block ERK1/2-CREB signaling. We did not observe a complete reversal of depression-like behaviors to control levels by β-asarone. To our knowledge, the present study is the first to demonstrate that adult neurogenesis is involved in the antidepressant-like behavioral effects of β-asarone, suggesting that β-asarone is a promising candidate for the treatment of depression.
The artillery weapon system,characterized as a complex nonlinear mechanical system, is influenced by various factors affecting its muzzle vibration response.In the article, the model of the artillery ...system with variable cross-section and multistep barrel is established on the basis of the bending deformation equation, and the fundamental frequency equation is obtained, and the auxiliary verification is completed through modal testing and finite element methods. Then, considering the clearance between the barrel and the cradle, the equivalent nonlinear dynamic model of the vertical vibration of the muzzle is established is established. Furthermore, the multi-scale analysis method obtains the amplitude-frequency curve of the equivalent model under sinusoidal excitation, and analyzes the influence of parameters on the response characteristics. Finally, the vibration research system of the model of the artillery system is constructed to study the vibration characteristics of the muzzle. The results show that the equivalent nonlinear dynamic model established in the paper has certain accuracy, which can provide a certain reference for the related research of the artillery system
Article highlights
An model for predicting the equivalent normal stiffness and fundamental frequency of vertical vibration of the muzzle in variable cross-section and multi-step barrel is established on the basis of quadratic integral method and Rayleigh method
The impact of clearance and excitation on the response characteristics of the artillery system is examined for providing a reference for the design of the system.
The accuracy and universality of the equivalent nonlinear dynamic model of the vertical vibration of the muzzle, considering the clearance, were verified by the vibration experiment.
In this work, the bacterial inactivation effects of shock waves, ultraviolet (UV) light, and electric field produced by high-voltage pulsed discharge in liquid with needle-plate configurations were ...studied. The contributions of each effect on the bacterial killing ratio in the discharge process were obtained individually by modifying reactor type and usage of glass, quartz, and black balloons. The results showed that the location from the discharge center axis significantly influenced the effects of shock waves and electric fields, although the effect of UV light was not affected by the location in the reactor. The effects of shock waves and electric fields were improved by decreasing the distance from the discharge center axis. Under this experimental condition, the effects of shock waves, UV light, and electric fields produced by discharges on bacterial inactivation were approximately 36.1%, 30.8%, 12.7%, respectively. Other contributions seemed to be due to activated species.
•Bacterial inactivation effects of various substances from a discharge were studied.•Reactor location affects shock waves and electric fields, but not UV.•Effects of shock waves, electric fields improved with a short discharge center axis.
A comprehensive profiling of the vaginal microbial communities and their variability enables an accurate description of the microbiome in women. However, there is a lack of studies available on ...Chinese women. In the present study, the composition of the vaginal microbiota during pregnancy and the 6-week postpartum period of 454 Chinese women was characterized by sequencing the V3–V4 region of the 16S ribosomal RNA (rRNA) gene. The vaginal microbiome showed variations during pregnancy and the postpartum period based on the abortion history, hypertensive disorders, delivery mode, and maternal age. Co-variation of 22 bacterial taxa, including the Lactobacillus genus and two of its species, may account for the common characteristics of the vaginal microbiome under scenarios of different medical histories and pregnancy outcomes. In contrast, discriminant bacterial species were significantly different between women who had preterm birth (PTB) with and without premature rupture of membranes (PROM), and the community state type (CST) IV-A without any predominant Lactobacillus species in the microbiota was more prevalent during pregnancy in the PROM-PTB cases, suggesting that specific bacterial species could be considered to distinguish between different types of PTB. By providing data on Chinese women, this study will enrich the knowledge of the human microbiome and contribute to a better understanding of the association between the vaginal microbiome and reproductive health.
In this paper, a dynamic model of an offshore drilling riser is developed based on the Hamilton principle. The developed dynamic model is transformed into a finite element model by introducing an ...approximate solution which chooses the Hermite cubic interpolation function of bending beam element as the shape function. Thereafter, the standard Newmark integration is applied to numerically simulate the dynamic responses of offshore drilling risers with varied system parameters, including the length of riser, top tension ratio, and buoyant factor. Based on the results of numerical simulation, under the influences of sea wind, sea current, and the periodic excitation of sea wave, the offshore drilling riser experiences a fast lateral deflection phase in the beginning, a reciprocating deflection phase in the following long duration, and then, a periodic oscillation when it reaches the dynamic stable condition, respectively. The riser system working in deeper water with a higher top tension ratio and a lower buoyant factor shows more controllable vibration and less lateral deflection.
To study the output power and wake flow characteristics of a wind turbine with swept blades, taking the blade tip offset and the location of the sweep start as two variables, the straight blade of ...the DTU-LN221 baseline airfoil was optimally designed with sweep. Then the designed wind turbine was numerically simulated, and the swept blade with the best optimal output power characteristics was selected for the wind tunnel test. The results indicate that for both forward and backward swept blades, increasing the blade tip offset and the sweep start location could decrease the power and thrust coefficients. Compared with the backward swept design, the forward swept design significantly improved the blades’ power characteristics. By adopting swept blades instead of straight blades, wind turbines could generate more power at high tip speed ratios, especially in yaw conditions. The streamwise velocity recovery of the wind turbine with swept blades was slower than that with straight blades as the lateral velocity near the wake region was higher than that with straight blades. Besides, the wind turbine with swept blades had a greater turbulence intensity of the wake near the wake center than that with straight blades with or without yaw condition.
To accurately calculate the unsteady dynamic load and output performance of the rotor in the stand-alone large-scale wind turbine, a novel added mass force expression
is derived and corresponding ...dynamic wake model is established using the acceleration potential flow theory and the blade element momentum in the present study. Moreover, induced velocity delay, wind shear, and yaw are considered in the proposed model. Referring to IEC61400-1 standard of the wind turbine, numerical models of turbulence, gust and wind direction change are established to investigate the output performance of the rotor under the combined effect of aerodynamic force, gravity, and centrifugal force. The obtained results show that the axial load and flapwise bending moment of the blade root are mainly determined by the axial aerodynamic component, while the tangential load and edgewise bending moment are mainly determined by the gravity component of the blade. It is found that the wind shear has a significant impact on the axial load and flapwise bending moment. Meanwhile, the axial thrust and rotor power are mainly affected by the inflow wind speed. It is observed that when the yaw angle exceeds 9.25°, the axial thrust and power of the rotor decrease obviously. The research results are compared with the experimental data from the NREL, it is found that the proposed model provides a new choose for the calculation of added mass force, and it has more calculation accuracy compared with classical BEM method in the prediction of unsteady dynamic load and output performance of the rotor.
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