Optimization of Processing Parameters of Power Spinning for Bushing Based on Neural Network and Genetic Algorithms

A neural network model of key process parameters and forming quality is developed based on training samples which are obtained from the orthogonal experiment and the finite element numerical simulation. Optimization of the process parameters is conducted using the genetic algorithm (GA). The experimental results have shown that a surface model of the neural network can describe the nonlinear implicit relationship between the parameters of the power spinning process:the wall margin and amount of expansion. It has been found that the process of determining spinning technological parameters can be accelerated using the optimization method developed based on the BP neural network and the genetic algorithm used for the process parameters of power spinning formation. It is undoubtedly beneficial towards engineering applications.

Conversion of Catalytically Inert 2D Bismuth Oxide Nanosheets for Effective Electrochemical Hydrogen Evolution Reaction Catalysis via Oxygen Vacancy Concentration Modulation

Oxygen vacancies(Vo)in electrocatalysts are closely correlated with the hydrogen evo-lution reaction(HER)activity.The role of vacancy defects and the effect of their concentration,how-ever,yet remains unclear.Herein,Bi2O3,an unfavorable electrocata-lyst for the HER due to a less than ideal hydrogen adsorption Gibbs free energy(ΔGH*),is utilized as a perfect model to explore the func-tion of Vo on HER performance.Through a facile plasma irradia-tion strategy,Bi2O3 nanosheets with different Vo concentrations are fabricated to evaluate the influence of defects on the HER process.Unexpectedly,while the generated oxygen vacancies contribute to the enhanced HER performance,higher Vo concentrations beyond a saturation value result in a significant drop in HER activity.By tunning the Vo concentration in the Bi_(2)O_(3)nanosheets via adjusting the treatment time,the Bi2O3 catalyst with an optimized oxygen vacancy concentration and detectable charge carrier concentration of 1.52×10^(24)cm^(−3)demonstrates enhanced HER performance with an overpotential of 174.2 mV to reach 10 mA cm^(−2),a Tafel slope of 80 mV dec−1,and an exchange current density of 316 mA cm−2 in an alkaline solution,which approaches the top-tier activity among Bi-based HER electrocatalysts.Density-functional theory calculations confirm the preferred adsorption of H*onto Bi2O3 as a function of oxygen chemical potential(ΔμO)and oxygen partial potential(PO2)and reveal that high Vo concentrations result in excessive stability of adsorbed hydrogen and hence the inferior HER activity.This study reveals the oxygen vacancy concentration-HER catalytic activity relationship and provides insights into activating catalytically inert materials into highly efficient electrocatalysts.

Thermal conduction of one-dimensional carbon nanomaterials and nanoarchitectures

This review summarizes the current studies of the thermal transport properties of one-dimensional(1D)carbon nano-materials and nanoarchitectures.Considering different hybridization states of carbon,emphases are laid on a variety of 1D carbon nanomaterials,such as diamond nanothreads,penta-graphene nanotubes,supernanotnbes,and carbyne.Based on experimental measurements and simulation/calculation results,we discuss the dependence of the thermal conductivity of these 1D carbon nanomaterials on a wide range of factors,including the size effect,temperature influence,strain effect,and others.This review provides an overall understanding of the thermal transport properties of 1D carbon nanomaterials and nanoarchitectures,which paves the way for effective thermal management at nanoscale.

Influence of Structural Parameters of Turbocharger Floating Bearing on Its Dynamic Characteristic Coefficients

The structure parameters in an actual industrial production have a great influence on the coefficient of supercharger floating bearing dynamic characteristics,but there has been little systematic study so far.In this paper,the influence of structural parameters of the turbocharger floating bearing on its dynamic characteristic coefficientsis systematically investigated based on the theories of hydrodynamic lubrication and tribology.The influence of clearance ratio on eccentricity and the influence of internal to external radius ratios,and Sommerfeld number were analyzed.A new formula of responding characteristics of the oil film force caused by the displacement or velocity disturbance was deduced near an equilibrium in the steady state.Applying the newly developed formula,the dynamic characteristic was studied for floating bearings.Regularity for change of oil film stiffness and damping was analyzed with the structural parameters of floating bearing such as radius ratios and eccentricity.It has been found that the clearance ratio increases with eccentricity when the radius ratio is unchanged.The eccentricity decreases with the internal to external radius ratio of floating rings when the clearance ratio is constant.The absolute value of total principal stiffness and total main damping decrease with the clearance ratio and radius ratio of floating rings when the total cross damping is stable.The results and findings in this paper can contribute to nonlinear dynamics designs of turbocharger rotor-bearing systems.

Stress relaxation analysis of single chondrocytes using porohyperelastic model based on AFM experiments

Based on atomic force microscopy technique, we found that the chon- drocytes exhibits stress relaxation behavior. We explored the mechanism of this stress relaxation behavior and concluded that the intracellular fluid exuding out from the cells during deformation plays the most important role in the stress relax- ation. We applied the inverse finite element analysis technique to determine nec- essary material parameters for porohyperelastic （PHE） model to simulate stress relaxation behavior as this model is proven capable of capturing the non-linear behavior and the fluid-solid interaction during the stress relaxation of the single chondrocytes. It is observed that PHE model can precisely capture the stress re- laxation behavior of single chondrocytes and would be a suitable model for cell biomechanics.

Tensile properties of functionalized carbon nanothreads

Low dimensional sp~3 carbon nanostructures have attracted increasing attention recently, due to their unique properties and appealing applications. Based on in silico studies, this work exploits the impacts from functional groups on the tensile properties of carbon nanothreads(NTH)– a new sp~3 carbon nanostructure. It is found that functional groups will alter the local bond configuration and induce initial stress concentration, which significantly reduces the fracture strain/strength of NTH. Different functional types lead to different local bond reconfigurations, and introduce different impacts on NTH. Further studies reveal that the tensile properties decreases generally when the content of functional groups increases. However, some NTHs with higher content of functional groups exhibit higher fracture strain/strength than their counterparts with lower percentage. Such observations are attributed to the synergetic effects from the sample length, self-oscillation, and distribution of functional groups. Simulations show that the tensile behaviour of NTH with the same functional percentage differs when the distribution pattern varies. Overall, ethyl groups are found to induce larger degradation on the tensile properties of NTH than methyl and phenyl groups. This study provides a comprehensive understanding of the influence from functional groups, which should be beneficial to the engineering applications of NTH.

Physical mechanism of the compressive response of F-actin networks:significance of crosslinker unbinding events

A model of crosslinker unbinding is implemented in a highly coarse- grained granular model of F-actin cytoskeleton. We employ this specific granular model to study the mechanisms of the compressive responses of F-actin networks. It is found that the compressive response of F-actin cytoskeleton has dependency on the strain rate. The evolution of deformation energy in the network indicates that crosslinker unbinding events can induce the remodelling of F-actin cytoskele- ton in response to external loadings. The internal stress in F-actin cytoskeleton can efficiently dissipate with the help of crosslinker unbinding, which could lead to the soontaneous relaxation of living cells.

Shape dependent protein-induced stabilization of gold nanoparticles:From a protein corona perspective Special Collection:Distinguished Australian Researchers

Gold nanoparticles(AuNPs)are promising materials for many bioapplications.However,upon contacting with biological media,AuNPs undergo changes.The interaction with proteins results in the so-called protein corona(PC)around AuNPs,leading to the new bioidentity and optical properties.Understanding the mechanisms of PC formation and its functions can help us to utilise its benefits and avoid its drawbacks.To date,most of the previous works aimed to understand the mechanisms governing PC formation and focused on the spherical nanoparticles,although non-spherical nanoparticles are designed for a wide range of applications in biosensing.In this work,we investigated the differences in PC formation on spherical and anisotropic AuNPs(nanostars in particular)from the joint experimental(extinction spectroscopy,zeta potential and surface-enhanced Raman scattering[SERS])and computational methods(the finite element method and molecular dynamics[MD]simulations).We discovered that protein does not fully cover the surface of anisotropic nanoparticles,leaving SERS hot-spots at the tips and high curvature edges‘available’for analyte binding(no SERS signal after pre-incubation with protein)while providing protein-induced stabilization(indicated by extinction spectroscopy)of the AuNPs by providing a protein layer around the particle’s core.The findings are confirmed from our MD simulations,the adsorption energy significantly decreases with the increased radius of curvature,so that tips(adsorption energy:2762.334 kJ/mol)would be the least preferential binding site compared to core(adsorption energy:11819.263 kJ/mol).These observations will help the development of new nanostructures with improved sensing and targeting ability.