Life prediction and test period optimization research based on small sample reliability test of hydraulic pumps

Hydraulic pumps belong to reliable long-life hydraulic components. The reliability evaluation includes characters such as long test period,high cost,and high power loss and so on. Based on the principle of energy-saving and power recovery,a small sample hydraulic pump reliability test rig is built,and the service life of hydraulic pump is predicted,and then the sampling period of reliability test is optimized. On the basis of considering the performance degradation mechanism of hydraulic pump,the feature information of degradation distribution of hydraulic pump volumetric efficiency during the test is collected,so an optimal degradation path model of feature information is selected from the aspect of fitting accuracy,and pseudo life data are obtained. Then a small sample reliability test of period constrained optimization search strategy for hydraulic pump is constructed to solve the optimization problem of the test sampling period and tightening end threshold,and it is verified that the accuracy of the minimum sampling period by the non-parametric hypothes is tested. Simulation result shows it could possess instructional significance and referenced value for hydraulic pump reliability life evaluation and the test's research and design.

Mechanical behavior of Ti-6Al-4V lattice-walled tubes under uniaxial compression

The compression behavior of the lattice-walled tubes under variable strain rates are investigated by numerical simulation,and the stress-strain relationship of the structure under quasi-static loading is theoretically analyzed.The finite element software LS-DYNA is used to simulate the structure established by the beam element,and the critical impact velocity is obtained when the structure collapses layer by layer.According to the plastic hinge theory and considering the combined action of the beam's bending moment and axial force in the structure,the stress-strain relationship of the structure under quasi-static loading is derived and compared with the experimental results.The numerical simulation results reveal that the structure of the single-layer gradient tube(SGC)does not undergo shear deformation under quasi-static and low-speed impact.The critical speed of the gradient square tube(GS)is higher than that of a cylindrical tube.The theoretical model can correctly reflect the mechanical response of the structure under uniaxial compression.

Biomimetic injectable hydrogel microspheres with enhanced lubrication and controllable drug release for the treatment of osteoarthritis

The occurrence of osteoarthritis(OA)is highly associated with the reduced lubrication property of the joint,where a progressive and irreversible damage of the articular cartilage and consecutive inflammatory response dominate the mechanism.In this study,bioinspired by the super-lubrication property of cartilage and catecholamine chemistry of mussel,we successfully developed injectable hydrogel microspheres with enhanced lubrication and controllable drug release for OA treatment.Particularly,the lubricating microspheres(GelMA@DMA-MPC)were fabricated by dip coating a self-adhesive polymer(DMA-MPC,synthesized by free radical copolymerization)on superficial surface of photo-crosslinked methacrylate gelatin hydrogel microspheres(GelMA,prepared via microfluidic technology),and encapsulated with an anti-inflammatory drug of diclofenac sodium(DS)to achieve the dual-functional performance.The tribological test and drug release test showed the enhanced lubrication and sustained drug release of the GelMA@DMA-MPC microspheres.In addition,the functionalized microspheres were intra-articularly injected into the rat knee joint with an OA model,and the biological tests including qRT-PCR,immunofluorescence staining assay,X-ray radiography and histological staining assay all revealed that the biocompatible microspheres provided significant therapeutic effect against the development of OA.In summary,the injectable hydrogel microspheres developed herein greatly improved lubrication and achieved sustained local drug release,therefore representing a facile and promising technique for the treatment of OA.

Bioinspired surface functionalization of biodegradable mesoporous silica nanoparticles for enhanced lubrication and drug release

Osteoarthritis is associated with the significantly increased friction of the joint,which results in progressive and irreversible damage to the articular cartilage.A synergistic therapy integrating lubrication enhancement and drug delivery is recently proposed for the treatment of early-stage osteoarthritis.In the present study,bioinspired by the self-adhesion performance of mussels and super-lubrication property of articular cartilages,a biomimetic self-adhesive dopamine methacrylamide-poly(2-methacryloyloxyethyl phosphorylcholine)(DMA-MPC)copolymer was designed and synthesized via free radical polymerization.The copolymer was successfully modified onto the surface of biodegradable mesoporous silica nanoparticles(bMSNs)by the dip-coating method to prepare the dual-functional nanoparticles(bMSNs@DMA-MPC),which were evaluated using a series of surface characterizations including the transmission electron microscope(TEM),Fourier transform infrared(FTIR)spectrum,thermogravimetric analysis(TGA),X-ray photoelectron spectroscopy(XPS),etc.The tribological test and in vitro drug release test demonstrated that the developed nanoparticles were endowed with improved lubrication performance and achieved the sustained release of an anti-inflammatory drug,i.e.,diclofenac sodium(DS).In addition,the in vitro biodegradation test showed that the nanoparticles were almost completely biodegraded within 10 d.Furthermore,the dual-functional nanoparticles were biocompatible and effectively reduced the expression levels of two inflammation factors such as interleukin-1β(IL-1β)and interleukin-6(IL-6).In summary,the surface functionalized nanoparticles with improved lubrication and local drug release can be applied as a potential intra-articularly injected biolubricant for synergistic treatment of early-stage osteoarthritis.

Self-adhesive lubricated coating for enhanced bacterial resistance

Limited surface lubrication and bacterial biofilm formation pose great challenges to biomedical implants.Although hydrophilic lubricated coatings and bacterial resistance coatings have been reported,the harsh and tedious synthesis greatly compromises their application,and more importantly,the bacterial resistance property has seldom been investigated in combination with the lubrication property.In this study,bioinspired by the performances of mussel and articular cartilage,we successfully synthesized self-adhesive lubricated coating and simultaneously achieved optimal lubrication and bacterial resistance properties.Additionally,we reported the mechanism of bacterial resistance on the nanoscale by studying the adhesion interactions between biomimetic coating and hydrophilic/hydrophobic tip or living bacteria via atomic force microscopy.In summary,the self-adhesive lubricated coating can effectively enhance lubrication and bacterial resistance performances based on hydration lubrication and hydration repulsion,and represent a universal and facial strategy for surface functionalization of biomedical implants.

Mth-power-law method to compensate laser linewidth of 100 Gb/s PDM-CO-OFDM systems

Laser linewidth is the important determinant of applying coherent optical orthogonal frequency division multiplexing （CO-OFDM） in optical transmission systems. The laser linewidth impairments in 100-Gb/s polarization division multiplexing CO-OFDM （PDM-CO-OFDM） system without optical dispersion com- pensation are compensated by the phase drift compensator （PDC） based on Mth-power-law method located at the receiver. PDC is more effective to compensate the phase drift due to laser linewidth. Simulating results show that the maximum Q factor can be increased by almost 〉10.0 dB for bemk-to-back （BtoB）. For the 100-kHz linewidth system of 800-km system, a benefit of about 4.9 dB is possible for the maximum Q factor.

Biodegradable lubricating mesoporous silica nanoparticles for osteoarthritis therapy

Osteoarthritis is characterized by lubrication failure of the articular cartilage and severe inflammation of the joint capsule.Lubricating mesoporous silica nanoparticles(MSNs)have been developed for the treatment of osteoarthritis based on enhanced lubrication and local drug delivery.However,MSNs are difficult to degrade in vivo in a short time,resulting in potential toxic effect due to bioaccumulation.In this study,biodegradable MSNs(bMSNs)were prepared through an oil–water biphase stratification method,and modified with poly(2-methacryloyloxyethyl phosphocholine)(PMPC)to synthesize lubricating drug-loaded nanoparticles(bMSNs–NH_(2)@PMPC)by photopolymerization.The in vitro degradation test demonstrated that the bMSNs and bMSNs–NH_(2)@PMPC almost degraded within 7 days.The tribiological test showed that the lubrication property of the bMSNs–NH2@PMPC was greatly improved,with a reduction of 50%in the friction coefficient(COF)compared with the bMSNs.It was attributed to hydration lubrication mechanism by which a tenacious hydration layer is formed surrounding the zwitterionic headgroups(N+(CH_(3))^(3)and PO4-)in PMPC polyelectrolyte polymer.Additionally,the bMSNs–NH_(2)@PMPC maintained excellent lubrication property under degradation and achieved sustained drug release behavior compared with the bMSNs.In summary,the biodegradable bMSNs–NH2@PMPC developed in this study with the properties of enhanced lubrication and drug delivery may be a promising approach for osteoarthritis therapy.