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51 result(s) for "Xu, Guang-Fei"
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Research on time-delayed vibration reduction control of 1/4 vehicle semi-active suspension system with three degrees of freedom
This paper is dedicated to the fundamental research of the mechanical model of a 1/4-vehicle semi-active suspension system with time-delayed state feedback control during wheel vertical displacement. The strategy combining the “equivalent harmonic excitation” optimization algorithm with the particle swarm optimization algorithm is proposed in this paper. Through the optimization and solution of time-delayed feedback control parameters of the 1/4 vehicle semi-active suspension system, the dynamic response of the vehicle suspension system before and after parameter optimization is studied. The research results indicate that, compared to passive control, time-delayed feedback control of wheel vertical displacement can significantly improve the smoothness, handling stability, and safety of vehicle operation.
Association of alcohol consumption and components of metabolic syndrome among people in rural China
BACKGROUND: Accumulative evidence in the literature suggests alcohol consumption is a protective factor of the metabolic syndrome (MS). However, few studies investigated the relationship between alcohol consumption and components of MS. We examined association of several types of alcoholic beverage with components of MS among people in rural China. METHODS: In the Nantong Metabolic Syndrome Study (NMSS), a cross-sectional study, a total of 20,502 participants, including 13,505 women and 6,997 men aged 18–74 years, were recruited between 2007 and 2008 in Nantong, China. Socio-economic status, dietary intake, physical exercise, alcoholic beverage consumption, and smoking status information were obtained, and triglycerides (TG), high-density lipoprtein cholesterol (HDL-c), blood pressure (BP) and blood glucose level were examined for all participants. Logistic regression model and the restricted cubic spline approach were used to analyze the associations between alcoholic beverage consumption and MS components. RESULTS: The MS prevalence was 21.1% in the whole population, which was significantly low among drinkers (20.6%), compared with non-drinkers (23.6%) in women, and was comparable in men (16.4% versus 17.1%). High HDL-c level was observed among drinkers, compared with non-drinkers in both men and women. Low TG level and Systolic BP (SBP) were found only among rice wine drinkers in women, and high waist circumference, high TG and BP were found among beer and liquor drinkers in men. Furthermore, we found that the highest quartile of rice wine drink in women may decrease 24% risk of high TG, 30% risk of low HDL-c and 43% risk of high glucose among MS components cases respectively, compared with non-drinkers (p for trend <0.01 for those three components). While compared non-drinkers among men, the highest quartile of liquor drink may increase 32% risk of high SBP, 55% risk of high Diastolic BP (DBP) and 34% risk of abdominal obesity among MS components cases respectively, but decrease 45% risk of low HDL-c (p for trend <0.05 for those four components). CONCLUSION: Our data suggested that all alcoholic beverages increased HDL-c level. Rice wine decreased both TG level and blood glucose in women only and it could be one of healthy alcoholic beverages in MS prevention in Chinese women. While excessive liquor consumption increased BP and waist circumference level and it may lead to hypertension and central obesity in Chinese men.
Optimization design and experiment on feeding and chopping device of silage maize harvester
Horizontal feeding devices and plate hob chopping devices are the key component of silage maize harvester. To solve the problem of feeding blockage, reduce energy consumption, and improve the chopping quality of the chopping device a horizontal different diameter five-rollers device (HDDFD) was designed and the plate hob chopping device was simultaneously optimized and analyzed. Through the dynamic analysis, the feeding conveying speed was detennined to be 2.0-4.5 m/s. The distance equation of the actual and theoretical cutting-edge curve and the position of the fixed blade were finally obtained. Single factor and response surface orthogonal tests in the bench site were carried out with feeding speed, rotating speed of chopping cylinder, feeding amount, and feeding direction as influencing factors, standard grass length rate (SGLR), and energy consumption per unit mass (ECPUM) as evaluation indexes. The optimal working parameters for chopping performance could be concluded as a feeding speed of 3.39 m/s, rotating speed of the chopping cylinder of 1016.17 r/min, feeding amount of 8.04 kg/s, and feeding direction of 52.2°. In addition, the SGLR and ECPUM were obtained as 95.35% and 37.63 kJ/kg, respectively. The relative error between the experimental results with round parameter combination and the predicted value was verified to be less than 5%. Field tests verified the reliability of the optimized feeding and chopping device. It can be seen that the HDDFD and optimized plate hob chopping device can meet the requirements of mechanized silage harvesting which obviously improves the working quality and reduce the energy consumption of chopping.
The Preparation of Fe3O4 Magnetic Nanometer Particle by Co-Precipitation Method
In this paper, the Fe3O4 magnetic nanometer particle was prepared by co-precipitation method. At the same time, the samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the surface active agent (PEG4000) can be good for the dispersion performance of Fe3O4 magnetic nanometer particle; and the temperature of 80°C is the appropriate drying temperature to prepare the Fe3O4 magnetic nanometer particle.
Failure Analysis of Hydrogen Corrosion of the Lens Gasket
The 10MoWVNb steel lens gaskets are widely used for the flange linking of high pressure tube in the synthetic ammonia system in chemical fertilizer plant. The gasket worked in H2-N2-NH3 environment at the temperature of 300°C. It often fails because of hydrogen corrosion. The microstructure and corrosion characteristic of the lens gasket were studied by optical microscope. The results showed that the hydrogen blister appeared preferentially at the interface of inclusions. The corrosion depth was 0.65 millimeter. There were little intergranular crack on inner surface.
Tribological behaviour of biomedical Ti-Zr-based shape memory alloys
The tribological behaviour of Ti-30Zr, Ti-20Zr-10Nb and Ti-19Zr-10Nb-1Fe alloys was investigated using reciprocating friction and wear tests. X-ray diffraction(XRD) results indicate that Ti-30Zr, Ti-20Zr-10Nb and Ti-19Zr-10Nb-1Fe alloys are composed of hexagonal a'-martensite, orthorhombic a''-martensite and bcc β phases,respectively. Ti-30Zr alloy has the highest hardness of HV(273.1 ± 9.3), while Ti-20Zr-10Nb alloy exhibits the lowest hardness of HV(235.2 ± 20.4) among all the alloys.The tribological results indicate that Ti-30Zr alloy shows the best wear resistance among these alloys, corresponding to the minimum average friction coefficient of 0.052 and the lowest wear rate of 6.4x10^-4mm3·N^-1·m^-1. Ti-20Zr-10Nb alloy displays better wear resistance than Ti-19Zr-10Nb-1Fe alloy, because the iron oxide is easy to fall off and less Nb2O5 films form on the worn surface of the latter.Delamination and abrasive wear in association with adhesive wear are the main wear mechanism of these alloys.
Tribological behaviour of biomedical Ti–Zr-based shape memory alloys
The tribological behaviour of Ti–30Zr, Ti–20Zr–10Nb and Ti–19Zr–10Nb–1Fe alloys was investigated using reciprocating friction and wear tests. X-ray diffraction(XRD) results indicate that Ti–30Zr, Ti–20Zr–10Nb and Ti–19Zr–10Nb–1Fe alloys are composed of hexagonal a’-martensite, orthorhombic a’’-martensite and bcc β phases,respectively. Ti–30Zr alloy has the highest hardness of HV(273.1 ± 9.3), while Ti–20Zr–10Nb alloy exhibits the lowest hardness of HV(235.2 ± 20.4) among all the alloys.The tribological results indicate that Ti–30Zr alloy shows the best wear resistance among these alloys, corresponding to the minimum average friction coefficient of 0.052 and the lowest wear rate of 6.4x10-4mm3·N-1·m-1. Ti–20Zr–10Nb alloy displays better wear resistance than Ti–19Zr–10Nb–1Fe alloy, because the iron oxide is easy to fall off and less Nb2O5 films form on the worn surface of the latter.Delamination and abrasive wear in association with adhesive wear are the main wear mechanism of these alloys.
Synthesis of Polyaniline Coating on the Modified Fiber Ball and Application for Cr(VI) Removal
In this study, polyaniline (PANI) is prepared by means of chemical oxidization polymerization and directly loaded on the modified fiber ball (m-FB) to obtain macroscale polyaniline/modified fiber ball (PANI/m-FB) composite, and then its removal ability of Cr(VI) is investigated. The effects of different parameters such as contact time, pH value and initial concentration on Cr(VI) removal efficiency are discussed. The experimental results illustrate that the favorable pH value is 5.0 and the maximum removal capacity is measured to be 293.13 mg g−1. Besides, PANI/m-FB composites can be regenerated and reused after being treated with strong acid. The kinetic study indicates that the adsorption procedure is mainly controlled by chemical adsorption. More importantly, the macroscale of composites can avoid secondary pollution efficiently. Benefiting from the low cost, easy preparation in large scale, environmentally friendly, excellent recycling performance as well as high removal ability, PANI/m-FB composites exhibit a potential possibility to remove Cr(VI) from industrial waste water.Graphic AbstractThe polyaniline (PANI) was coated on modified fiber ball (m-FB) to remove Cr(VI) in waste water, and this kind of PANI/m-FB composites can avoid secondary pollution efficiently due to its macrostructure. Furthermore, the removal capacity can reach to 291.13 mg/g and can be multiple reused.
Melatonin improves influenza virus infection-induced acute exacerbation of COPD by suppressing macrophage M1 polarization and apoptosis
Background Influenza A viruses (IAV) are extremely common respiratory viruses for the acute exacerbation of chronic obstructive pulmonary disease (AECOPD), in which IAV infection may further evoke abnormal macrophage polarization, amplify cytokine storms. Melatonin exerts potential effects of anti-inflammation and anti-IAV infection, while its effects on IAV infection-induced AECOPD are poorly understood. Methods COPD mice models were established through cigarette smoke exposure for consecutive 24 weeks, evaluated by the detection of lung function. AECOPD mice models were established through the intratracheal atomization of influenza A/H3N2 stocks in COPD mice, and were injected intraperitoneally with melatonin (Mel). Then, The polarization of alveolar macrophages (AMs) was assayed by flow cytometry of bronchoalveolar lavage (BAL) cells. In vitro, the effects of melatonin on macrophage polarization were analyzed in IAV-infected Cigarette smoking extract (CSE)-stimulated Raw264.7 macrophages. Moreover, the roles of the melatonin receptors (MTs) in regulating macrophage polarization and apoptosis were determined using MTs antagonist luzindole. Results The present results demonstrated that IAV/H3N2 infection deteriorated lung function (reduced FEV 20,50 /FVC), exacerbated lung damages in COPD mice with higher dual polarization of AMs. Melatonin therapy improved airflow limitation and lung damages of AECOPD mice by decreasing IAV nucleoprotein (IAV-NP) protein levels and the M1 polarization of pulmonary macrophages. Furthermore, in CSE-stimulated Raw264.7 cells, IAV infection further promoted the dual polarization of macrophages accompanied with decreased MT1 expression. Melatonin decreased STAT1 phosphorylation, the levels of M1 markers and IAV-NP via MTs reflected by the addition of luzindole. Recombinant IL-1β attenuated the inhibitory effects of melatonin on IAV infection and STAT1-driven M1 polarization, while its converting enzyme inhibitor VX765 potentiated the inhibitory effects of melatonin on them. Moreover, melatonin inhibited IAV infection-induced apoptosis by suppressing IL-1β/STAT1 signaling via MTs. Conclusions These findings suggested that melatonin inhibited IAV infection, improved lung function and lung damages of AECOPD via suppressing IL-1β/STAT1-driven macrophage M1 polarization and apoptosis in a MTs-dependent manner. Melatonin may be considered as a potential therapeutic agent for influenza virus infection-induced AECOPD. Graphical Abstract Schematic mechanisms underlying the regulatory effects of melatonin on macrophage polarization and apoptosis in IAV infection plus cigarette stimulation-induced AECOPD model.
TLR2-Melatonin Feedback Loop Regulates the Activation of NLRP3 Inflammasome in Murine Allergic Airway Inflammation
Toll-like receptor 2 (TLR2) is suggested to initiate the activation of NLRP3 inflammasome, and considered to be involved in asthma. The findings that melatonin modulates TLRs-mediated immune responses, together with the suppressing effect of TLRs on endogenous melatonin synthesis, support the possibility that a feedback loop exists between TLRs system and endogenous melatonin synthesis. To determine whether TLR2-melatonin feedback loop exists in allergic airway disease and regulates NLRP3 inflammasome activity, wild-type (WT) and TLR2 mice were challenged with OVA to establish allergic airway disease model. Following OVA challenge, WT mice exhibited increased-expression of TLR2, activation of NLRP3 inflammasome and marked airway inflammation, which were all effectively inhibited in the TLR2 mice, indicating that TLR2-NLRP3 mediated airway inflammation. Meanwhile, melatonin biosynthesis was reduced in OVA-challenged WT mice, while such reduction was notably rescued by TLR2 deficiency, suggesting that TLR2-NLRP3-mediated allergic airway inflammation was associated with decreased endogenous melatonin biosynthesis. Furthermore, addition of melatonin to OVA-challenged WT mice pronouncedly ameliorated airway inflammation, decreased TLR2 expression and NLRP3 inflammasome activation, further implying that melatonin in turn inhibited airway inflammation via suppressing TLR2-NLRP3 signal. Most interestingly, although melatonin receptor antagonist luzindole significantly reduced the protein expressions of ASMT, AANAT and subsequent level of melatonin in OVA-challenged TLR2 mice, it exhibited null effect on leukocytes infiltration, Th2-cytokines production and NLRP3 activity. These results indicate that a TLR2-melatonin feedback loop regulates NLRP3 inflammasome activity in allergic airway inflammation, and melatonin may be a promising therapeutic medicine for airway inflammatory diseases such as asthma.