A surface Ti-WC composite was fabricated on CP-Ti by surface friction stirring(SFS)using a pinless WC-Cotool at a processing window of 800−2500 r/min and 8−50 mm/min.At 1600 r/min-50 mm/min,a defect-free compositelaye...A surface Ti-WC composite was fabricated on CP-Ti by surface friction stirring(SFS)using a pinless WC-Cotool at a processing window of 800−2500 r/min and 8−50 mm/min.At 1600 r/min-50 mm/min,a defect-free compositelayer with an average hardness of~HV 1170 is formed.The hardness was increased by WC and TiN reinforcingparticles,dissolved Co atoms in Ti,and the formation of ultrafine grains.WC particles were incorporated into the Tisubstrate owing to the intense frictional interaction/heating at the tool-plate interface(~1000℃),which led to strengthloss and wear of the tool.The Williamson-Hall analysis of the XRD peaks of the SFSed sample confirmed a significantlysmall crystallite size(~100 nm).Wear tests showed that the wear resistance of the composite structure was about 4.5times higher than that of the CP-Ti.Friction analysis revealed a significant reduction in average value and fluctuations ofthe friction coefficient.展开更多
An active pipe-embedded building envelope, which is an external wall or roof with pipes embedded inside, was presented. This structure may utilize the circulating water in the pipe to transfer heat or coolth inside di...An active pipe-embedded building envelope, which is an external wall or roof with pipes embedded inside, was presented. This structure may utilize the circulating water in the pipe to transfer heat or coolth inside directly. This kind of structure is named ＂active pipe-embedded building envelope＂ due to dealing with the thermal energy actively inside the structure mass by circulating water. This structure not only deals with thermal energy before the external disturbance becomes cooling/heating load by using the circulating water, but also may use low-grade energy sources such as evaporative cooling, solar energy, and geothermal energy. In the meantime, this structure can also improve the indoor thermal comfort by tempering the internal wall surface temperature variation due to the thermal removal in the mass. This work further presents the thermal performance of this structure under a typical hot summer weather condition by comparing it with that of the conventional external wall/roof with numerical simulation. The results show that this pipe-embedded structure may reduce the external heat transfer significantly and reduce the internal wall surface temperature for improving thermal comfort. This work also presents the effects of the water temperature and the pipe spacing on the heat transfer of this structure. The internal surface heat transfer may reduce by about 2.6 W/mE when the water temperature reduces by 1℃ as far as a brick wall with pipes embedded inside is concerned. When the pipe spacing reduces by 50 mm, the internal wall surface heat flux can also reduce by about 2.3 W/m2.展开更多
According to Cubic law and incompressible fluid law of mass conservation, the seepage character of the fracture surface was simulated with the simulation method of fractal theory and random Brown function. Furthermore...According to Cubic law and incompressible fluid law of mass conservation, the seepage character of the fracture surface was simulated with the simulation method of fractal theory and random Brown function. Furthermore, the permeability coefficient of the single fracture was obtained. In order to test the stability of the method, 500 simulations were conducted on each different fractal dimension. The simulated permeability coefficient was analyzed in probability density distribution and probability cumulative distribution statistics. Statistics showed that the discrete degree of the permeability coefficient increases with the increase of the fractal dimension. And the calculation result has better stability when the fractal dimension value is relatively small. According to the Bayes theory, the characteristic index of the permeability coefficient on fractal dimension P（Dfi｜ Ri） is established. The index, P（Dfi｜ Ri）, shows that when the simulated permeability coefficient is relatively large, it can clearly represent the fractal dimension of the structure surface, the probability is 82%. The calculated results of the characteristic index verify the feasibility of the method.展开更多
Modeling of rough surfaces with given roughness parameters is studied,where surfaces with Gaussian height distribution and exponential auto-correlation function(ACF) are concerned.A large number of micro topography sa...Modeling of rough surfaces with given roughness parameters is studied,where surfaces with Gaussian height distribution and exponential auto-correlation function(ACF) are concerned.A large number of micro topography samples are randomly generated first using the rough surface simulation method with FFT.Then roughness parameters of the simulated roughness profiles are calculated according to parameter definition,and the relationship between roughness parameters and statistical distribution parameters is investigated.The effects of high-pass filtering with different cut-off lengths on the relationship are analyzed.Subsequently,computing formulae of roughness parameters based on standard deviation and correlation length are constructed with mathematical regression method.The constructed formulae are tested with measured data of actual topographies,and the influences of auto-correlation variations at different lag lengths on the change of roughness parameter are discussed.The constructed computing formulae provide an approach to active modeling of rough surfaces with given roughness parameters.展开更多
The production and properties of the biosurfactant synthesized by Bacillus subtilis CCTCC AB93108 were studied. The maximum concentration of the surfactant is 1.64 g/L when the bacteria grow in a medium supplemented w...The production and properties of the biosurfactant synthesized by Bacillus subtilis CCTCC AB93108 were studied. The maximum concentration of the surfactant is 1.64 g/L when the bacteria grow in a medium supplemented with glucose as carbon sources. The isolated biosurfactant is a complex of protein and polysaccharide without lipids. It reduces the surface tension of distilled water to 45.9 mN/m, and its critical micelle concentration (CMC) is 2.96 g/L. It can stabilize emulsions of several aromatic and aliphatic hydrocarbons, such as benzene, xylene, n-pentane, n-nonane, gasoline and diesel oil. It presents high emulsification activity and stability in a wide range of temperature (4-100 ℃) and a long period of duration.展开更多
The fatigue performance of a workpiece depends on its surface quality.In traditional fatigue life prediction,the effect of surface quality is commonly accounted for by using empirical correction factors,which is impre...The fatigue performance of a workpiece depends on its surface quality.In traditional fatigue life prediction,the effect of surface quality is commonly accounted for by using empirical correction factors,which is imprecise when safety is of great concern.For surface quality,the surface topography is an important parameter,which introduces stress concentration that reduces the fatigue life.It is not feasible to test the stress concentration of different surface topographies.On the one hand,it is time-consuming and high-cost,and on the other hand,it cannot reflect the general statistical characteristics.With the help of surface reconstruction technology and interpolation method,a more efficient and economic approach is proposed,where FE simulation of workpiece with the reconstructed surface topography is used as a foundation for fatigue life prediction.The relationship between surface roughness(Sa)and fatigue life of the workpiece is studied with the proposed approach.展开更多
Twelve samples with periodic array square pillars microstructure were prepared on the silicon wafer by plasma etching techniques, on which space b of the square pillars increased from 5 to 60 μm. In order to study th...Twelve samples with periodic array square pillars microstructure were prepared on the silicon wafer by plasma etching techniques, on which space b of the square pillars increased from 5 to 60 μm. In order to study the effect ofb on the wettability of the rough surface, the effects of apparent contact angle （CA） and sliding angle （a） of the droplet on the rough surface were measured with the contact angle meter. The results show that the experimental values of CA well agree with the classical wetting theory and a decreases with the increase of b. Two drop shapes exist on the samples＇ surface, corresponding to the Cassie state and the Wenzel state respectively. The contact state in which a drop would settle depends typically on the size of b. On the role of gravitation, the irreversible transition of a drop from Cassie state to Wenzel state should occur at a certain space of the square pillars. Since the transition has implications on the application of super-hydrophobic rough surfaces, theoretically, the prediction of wetting state transition on square pillar array micro-structured surfaces provides an intuitionistic guidance for the design of steady superhydrophobic surfaces.展开更多
To analyze the influence of surface texture on friction properties of Crl2MoV＇, ordinary grinder and spinning technology were adopted to obtain the grooved surface morphology of samples, and then the impact of spindl...To analyze the influence of surface texture on friction properties of Crl2MoV＇, ordinary grinder and spinning technology were adopted to obtain the grooved surface morphology of samples, and then the impact of spindle speed and feed in z-direction on surface morphology in the process of spinning was studied. In addition, the corresponding friction coefficient of sample was obtained through friction and wear tests. The results show that the peak clipping and the valley filling were conducted on the grinding surface, which could improve the surface roughness effectively and make the grinding trench-type wear scar more uniform. Both the area ratio of groove and groove spacing increased initially and then decreased with the increase of the spindle speed or the feed in z-direction. As a kind of micro-process, the groove could influence the friction coefficient of sample surface, whose distribution was beneficial to the reduction of friction coefficient. Compared with the surface obtained through ordinary grinding, grooved surface morphology through spinning technology was more conductive to reduce the friction coefficient, which could be reduced by 25%. When the friction coefficient of sample was reduced to the minimum, the texture of groove corresponded had an optimal area ratio and an optimal groove spacing, 37.5% and 27.5 μm, respectively.展开更多
Based on the hazard development mechanism, a water solution area is closely related to the supporting effect of pressure-bearing water, the relaxing and collapsing effect of orebody interlayer, the collapsing effect o...Based on the hazard development mechanism, a water solution area is closely related to the supporting effect of pressure-bearing water, the relaxing and collapsing effect of orebody interlayer, the collapsing effect of thawless material in orebody, filling effect caused by cubical expansibility of hydrate crystallization and uplifting effect of hard rock layer over cranny belt. The movement and deformation of ground surface caused by underground water solution mining is believed to be much weaker than that caused by well lane mining, which can be predicted by the stochastic medium theory method. On the basis of analysis on the engineering practice of water solution mining, its corresponding parameters can be obtained from the in-site data of the belt water and sand filling mining in engineering analog approach.展开更多
Most existing network representation learning algorithms focus on network structures for learning.However,network structure is only one kind of view and feature for various networks,and it cannot fully reflect all cha...Most existing network representation learning algorithms focus on network structures for learning.However,network structure is only one kind of view and feature for various networks,and it cannot fully reflect all characteristics of networks.In fact,network vertices usually contain rich text information,which can be well utilized to learn text-enhanced network representations.Meanwhile,Matrix-Forest Index(MFI)has shown its high effectiveness and stability in link prediction tasks compared with other algorithms of link prediction.Both MFI and Inductive Matrix Completion(IMC)are not well applied with algorithmic frameworks of typical representation learning methods.Therefore,we proposed a novel semi-supervised algorithm,tri-party deep network representation learning using inductive matrix completion(TDNR).Based on inductive matrix completion algorithm,TDNR incorporates text features,the link certainty degrees of existing edges and the future link probabilities of non-existing edges into network representations.The experimental results demonstrated that TFNR outperforms other baselines on three real-world datasets.The visualizations of TDNR show that proposed algorithm is more discriminative than other unsupervised approaches.展开更多
Stable and monodispersed silver nanoparticles were produced through a mild,convenient,one-pot method based on the reduction of silver nitrate in the presence of poly(amic acid) (PAA) as a stabilizer.The surface plasma...Stable and monodispersed silver nanoparticles were produced through a mild,convenient,one-pot method based on the reduction of silver nitrate in the presence of poly(amic acid) (PAA) as a stabilizer.The surface plasma band transition was monitored along with time in the reaction mixture for three sets of experiments by ultraviolet-visible spectroscopy.Analysis of the data with the Avrami equation yielded n exponent with values between 0.5 and 1.5,demonstrating three-dimensional heterogeneous nucleation and diffusion-controlled growth,accompanied by soft impingement effect.XRD and TEM analyses show a softly agglomerated polycrystalline state and a nearly spherical morphology (<50 nm) of nanoparticles.The FT-IR result indicates that the PAA molecular structure could be hardly influenced by the formation of nanoparticles.展开更多
A model for liquid-gas flow （MLGF）, considering the flee movement of liquid surface, was built to simulate the wastewater velocity field and gas distribution in a full-scale Caroussel oxidation ditch with surface ae...A model for liquid-gas flow （MLGF）, considering the flee movement of liquid surface, was built to simulate the wastewater velocity field and gas distribution in a full-scale Caroussel oxidation ditch with surface aeration. It was calibrated and validated by field measurement data, and the calibrated parameters and sections were selected based on both model analysis and numerical computation. The simulated velocities of MLGF were compared to that of a model for wastewater-sludge flow （MWSF）. The results show that the free liquid surface considered in MLGF improves the simulated velocity results of upper layer and surface. Moreover, distribution of gas volume fraction （GVF） simulated by MLGF was compared to dissolved oxygen （DO） measured in the oxidation ditch. It is shown that DO distribution is affected by many factors besides GVF distribution.展开更多
According to the two-dimensional(2-D) thermo-elasticity theory, the exact elasticity solution of the simply supported laminated beams subjected to thermo-loads was studied. An analytical method was presented to obtain...According to the two-dimensional(2-D) thermo-elasticity theory, the exact elasticity solution of the simply supported laminated beams subjected to thermo-loads was studied. An analytical method was presented to obtain the temperature, displacement and stress fields in the beam. Firstly, the general solutions of temperature, displacements and stresses for a single-layered simply supported beam were obtained by solving the 2-D heat conduction equation and the 2-D elasticity equations, respectively. Then, based on the continuity of temperature, heat flux, displacements and stresses on the interface of two adjacent layers, the formulae of temperature, displacements and stresses between the lowest layer and the top layer of the beam were derived out in a recurrent manner. Finally, the unknown coefficients in the solutions were determined by the use of the upper surface and lower surface conditions of the beam. The distributions of temperature, displacement and stress in the beam were obtained by substituting these coefficients back to the recurrence formulae and the solutions. The excellent convergence of the present method has been demonstrated and the results obtained by the present method agree well with those from the finite element method. The effects of surface temperatures, thickness, layer number and material properties of the plate on the temperature distribution were discussed in detail. Numerical results reveal that the displacements and stresses monotonically increase with the increase of surface temperatures. In particular, the horizontal stresses are discontinuous at the interface.展开更多
The electrodeposition of nickel-silicon carbide coatings on a copper electrode was done by mixing SiC particles in the nickel electrodeposition solution.The influence of surfactants and silicon carbide particle size o...The electrodeposition of nickel-silicon carbide coatings on a copper electrode was done by mixing SiC particles in the nickel electrodeposition solution.The influence of surfactants and silicon carbide particle size on uniformity and quantity of silicon carbide particles in nickel-silicon carbide composite coatings was investigated.It was found that particle size affects the nucleation overpotential,with 40 nm silicon carbide nanoparticles more effective in promoting nickel nucleation than 500 nm particles due to an increase in active nucleation sites.In terms of surfactants,anionic surfactant sodium dodecyl sulfate(SDS)produced better dispersion of 40 nm silicon carbide particles than cationic surfactant cetyltrimethyl ammonium bromide(CTAB),but little difference was found between the two when 500 nm silicon carbide particles were used.Thus,although the suspension of silicon carbide particles can be improved and their co-deposition can be promoted with a cationic surfactant CTAB,it is less effective than an anionic surfactant SDS in terms of surface finish.展开更多
Liquid nitriding of Cll0 steel was conducted in a wide range of temperatures （400-670 ℃） using a kind of chemical heat-treatments, and the hardness, mechanical and corrosion properties of the nitrided surface were ...Liquid nitriding of Cll0 steel was conducted in a wide range of temperatures （400-670 ℃） using a kind of chemical heat-treatments, and the hardness, mechanical and corrosion properties of the nitrided surface were evaluated. Experimental results revealed that the microstructure and phase constituents of the nitrided surface alloy are highly depended on the processing condition. When C 110 steel was subjected to liquid nitriding at 430 ℃, the nitrided layer was almost composed of a thin e-Fe2-3N layer. When C 110 steel was subjected to liquid nitriding at 640 ℃, the phase composition of the nitrided layer was greatly changed. The nitrided layer depth increased significantly with increasing the treating temperature. The liquid nitriding effectively improved the surface hardness. After liquid nitriding, the absorption energy of the treated sample decreased and the tensile strength increased by Charpy V-notch （CVN） test. But the elongation of treated sample decreased. The reason is that the nitrided layer of sample is hardened and there is brittlement by diffusion of nitrogen atom. Despite of treatment temperature, the liquid nitriding can improve the corrosion. After being nitrided at 430 ℃, the nitrided layer of the C110 steel was mainly composed by e-Fe2 3N, which has excellent corrosion resistance and high microhardness, the nitrided sample has the best corrosion resistance. After nitriding temperature over 580 ℃, especially at 680 ℃, the sample＇s surface was covered by the thick oxide layer, which has very low hardness and corrosion resistance. So, the corrosion resistance of samples is severely compromised.展开更多
Porous and dense TiNi alloys were successfully fabricated by powder metallurgy(P/M) method, and to further improve their surface biocompatibility, surface modification techniques including grind using silicon-carbide(...Porous and dense TiNi alloys were successfully fabricated by powder metallurgy(P/M) method, and to further improve their surface biocompatibility, surface modification techniques including grind using silicon-carbide(SiC) paper, acid etching and alkali treatment were employed to produce either irregularly rough surface or micro-porous surface roughness. X-ray diffractometry(XRD), scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDX) attached to SEM were used to characterize surface structure and the Ca-P coatings. Effects of the above surface treatments on the surface morphology, apatite forming ability were systematically investigated. Results indicate that all the above surface treatments increase the apatite forming ability of TiNi alloys in varying degrees when soaked in simulated body fluid(SBF). More apatite coatings formed on TiNi samples sintered at 1050℃ and 1100℃ due to their high porosity and pure TiNi phase that is beneficial to heterogeneous nucleation. Furthermore, more uniform apatite was fabricated on the sample sintered from the mixture of Ni and Ti powders.展开更多
文摘A surface Ti-WC composite was fabricated on CP-Ti by surface friction stirring(SFS)using a pinless WC-Cotool at a processing window of 800−2500 r/min and 8−50 mm/min.At 1600 r/min-50 mm/min,a defect-free compositelayer with an average hardness of~HV 1170 is formed.The hardness was increased by WC and TiN reinforcingparticles,dissolved Co atoms in Ti,and the formation of ultrafine grains.WC particles were incorporated into the Tisubstrate owing to the intense frictional interaction/heating at the tool-plate interface(~1000℃),which led to strengthloss and wear of the tool.The Williamson-Hall analysis of the XRD peaks of the SFSed sample confirmed a significantlysmall crystallite size(~100 nm).Wear tests showed that the wear resistance of the composite structure was about 4.5times higher than that of the CP-Ti.Friction analysis revealed a significant reduction in average value and fluctuations ofthe friction coefficient.
基金Project(51178201) supported by the National Natural Science Foundation of China Project(2011CDB292) supported by the Natural Science Foundation of Hubei Province,China
文摘An active pipe-embedded building envelope, which is an external wall or roof with pipes embedded inside, was presented. This structure may utilize the circulating water in the pipe to transfer heat or coolth inside directly. This kind of structure is named ＂active pipe-embedded building envelope＂ due to dealing with the thermal energy actively inside the structure mass by circulating water. This structure not only deals with thermal energy before the external disturbance becomes cooling/heating load by using the circulating water, but also may use low-grade energy sources such as evaporative cooling, solar energy, and geothermal energy. In the meantime, this structure can also improve the indoor thermal comfort by tempering the internal wall surface temperature variation due to the thermal removal in the mass. This work further presents the thermal performance of this structure under a typical hot summer weather condition by comparing it with that of the conventional external wall/roof with numerical simulation. The results show that this pipe-embedded structure may reduce the external heat transfer significantly and reduce the internal wall surface temperature for improving thermal comfort. This work also presents the effects of the water temperature and the pipe spacing on the heat transfer of this structure. The internal surface heat transfer may reduce by about 2.6 W/mE when the water temperature reduces by 1℃ as far as a brick wall with pipes embedded inside is concerned. When the pipe spacing reduces by 50 mm, the internal wall surface heat flux can also reduce by about 2.3 W/m2.
基金Project(50934006) supported by the National Natural Science Foundation of ChinaProject(CX2012B070) supported by Hunan Provincial Innovation Foundation for Postgraduate,ChinaProject(1343-76140000024) Supported by Academic New Artist Ministry of Education Doctoral Post Graduate in 2012,China
文摘According to Cubic law and incompressible fluid law of mass conservation, the seepage character of the fracture surface was simulated with the simulation method of fractal theory and random Brown function. Furthermore, the permeability coefficient of the single fracture was obtained. In order to test the stability of the method, 500 simulations were conducted on each different fractal dimension. The simulated permeability coefficient was analyzed in probability density distribution and probability cumulative distribution statistics. Statistics showed that the discrete degree of the permeability coefficient increases with the increase of the fractal dimension. And the calculation result has better stability when the fractal dimension value is relatively small. According to the Bayes theory, the characteristic index of the permeability coefficient on fractal dimension P（Dfi｜ Ri） is established. The index, P（Dfi｜ Ri）, shows that when the simulated permeability coefficient is relatively large, it can clearly represent the fractal dimension of the structure surface, the probability is 82%. The calculated results of the characteristic index verify the feasibility of the method.
基金Projects(51535012,U1604255)supported by the National Natural Science Foundation of ChinaProject(2016JC2001)supported by the Key Research and Development Project of Hunan Province,China
文摘Modeling of rough surfaces with given roughness parameters is studied,where surfaces with Gaussian height distribution and exponential auto-correlation function(ACF) are concerned.A large number of micro topography samples are randomly generated first using the rough surface simulation method with FFT.Then roughness parameters of the simulated roughness profiles are calculated according to parameter definition,and the relationship between roughness parameters and statistical distribution parameters is investigated.The effects of high-pass filtering with different cut-off lengths on the relationship are analyzed.Subsequently,computing formulae of roughness parameters based on standard deviation and correlation length are constructed with mathematical regression method.The constructed formulae are tested with measured data of actual topographies,and the influences of auto-correlation variations at different lag lengths on the change of roughness parameter are discussed.The constructed computing formulae provide an approach to active modeling of rough surfaces with given roughness parameters.
基金Project(IRT0719) supported by the Program for Changjiang Scholars and Innovative Research Team in University of China Project (2004AA649370) supported by the National High-Tech Research and Development Program of China+1 种基金 Projects(50425927, 50225926) supported by the Natural Foundation for Distinguished Young Scholars Project(2007F3102) supported by Technology Foundation for Creative Young Scholars of Fujian Province, China
文摘The production and properties of the biosurfactant synthesized by Bacillus subtilis CCTCC AB93108 were studied. The maximum concentration of the surfactant is 1.64 g/L when the bacteria grow in a medium supplemented with glucose as carbon sources. The isolated biosurfactant is a complex of protein and polysaccharide without lipids. It reduces the surface tension of distilled water to 45.9 mN/m, and its critical micelle concentration (CMC) is 2.96 g/L. It can stabilize emulsions of several aromatic and aliphatic hydrocarbons, such as benzene, xylene, n-pentane, n-nonane, gasoline and diesel oil. It presents high emulsification activity and stability in a wide range of temperature (4-100 ℃) and a long period of duration.
基金Projects(51535012,U1604255)supported by the National Natural Science Foundation of ChinaProject(2016JC2001)supported by the Key Research and Development Project of Hunan Province,China
文摘The fatigue performance of a workpiece depends on its surface quality.In traditional fatigue life prediction,the effect of surface quality is commonly accounted for by using empirical correction factors,which is imprecise when safety is of great concern.For surface quality,the surface topography is an important parameter,which introduces stress concentration that reduces the fatigue life.It is not feasible to test the stress concentration of different surface topographies.On the one hand,it is time-consuming and high-cost,and on the other hand,it cannot reflect the general statistical characteristics.With the help of surface reconstruction technology and interpolation method,a more efficient and economic approach is proposed,where FE simulation of workpiece with the reconstructed surface topography is used as a foundation for fatigue life prediction.The relationship between surface roughness(Sa)and fatigue life of the workpiece is studied with the proposed approach.
基金Project(50435030) supported by the National Natural Science foundation of ChinaProject supported by the Program for New Century Excellent Talents in Chinese University Project(GZ080010) supported by the Open Research Fund Program of Jiangsu Province Key Laboratory for Photon Manufacturing Science and Technology
文摘Twelve samples with periodic array square pillars microstructure were prepared on the silicon wafer by plasma etching techniques, on which space b of the square pillars increased from 5 to 60 μm. In order to study the effect ofb on the wettability of the rough surface, the effects of apparent contact angle （CA） and sliding angle （a） of the droplet on the rough surface were measured with the contact angle meter. The results show that the experimental values of CA well agree with the classical wetting theory and a decreases with the increase of b. Two drop shapes exist on the samples＇ surface, corresponding to the Cassie state and the Wenzel state respectively. The contact state in which a drop would settle depends typically on the size of b. On the role of gravitation, the irreversible transition of a drop from Cassie state to Wenzel state should occur at a certain space of the square pillars. Since the transition has implications on the application of super-hydrophobic rough surfaces, theoretically, the prediction of wetting state transition on square pillar array micro-structured surfaces provides an intuitionistic guidance for the design of steady superhydrophobic surfaces.
基金Project(51275543)supported by the National Natural Science Foundation,ChinaProject(KJ1603804)supported by the Research Projects of Chongqing Commission of Science and Technology,China
文摘To analyze the influence of surface texture on friction properties of Crl2MoV＇, ordinary grinder and spinning technology were adopted to obtain the grooved surface morphology of samples, and then the impact of spindle speed and feed in z-direction on surface morphology in the process of spinning was studied. In addition, the corresponding friction coefficient of sample was obtained through friction and wear tests. The results show that the peak clipping and the valley filling were conducted on the grinding surface, which could improve the surface roughness effectively and make the grinding trench-type wear scar more uniform. Both the area ratio of groove and groove spacing increased initially and then decreased with the increase of the spindle speed or the feed in z-direction. As a kind of micro-process, the groove could influence the friction coefficient of sample surface, whose distribution was beneficial to the reduction of friction coefficient. Compared with the surface obtained through ordinary grinding, grooved surface morphology through spinning technology was more conductive to reduce the friction coefficient, which could be reduced by 25%. When the friction coefficient of sample was reduced to the minimum, the texture of groove corresponded had an optimal area ratio and an optimal groove spacing, 37.5% and 27.5 μm, respectively.
基金Project(40404001) supported by the National Natural Science Foundation of China
文摘Based on the hazard development mechanism, a water solution area is closely related to the supporting effect of pressure-bearing water, the relaxing and collapsing effect of orebody interlayer, the collapsing effect of thawless material in orebody, filling effect caused by cubical expansibility of hydrate crystallization and uplifting effect of hard rock layer over cranny belt. The movement and deformation of ground surface caused by underground water solution mining is believed to be much weaker than that caused by well lane mining, which can be predicted by the stochastic medium theory method. On the basis of analysis on the engineering practice of water solution mining, its corresponding parameters can be obtained from the in-site data of the belt water and sand filling mining in engineering analog approach.
基金Projects(11661069,61763041) supported by the National Natural Science Foundation of ChinaProject(IRT_15R40) supported by Changjiang Scholars and Innovative Research Team in University,ChinaProject(2017TS045) supported by the Fundamental Research Funds for the Central Universities,China
文摘Most existing network representation learning algorithms focus on network structures for learning.However,network structure is only one kind of view and feature for various networks,and it cannot fully reflect all characteristics of networks.In fact,network vertices usually contain rich text information,which can be well utilized to learn text-enhanced network representations.Meanwhile,Matrix-Forest Index(MFI)has shown its high effectiveness and stability in link prediction tasks compared with other algorithms of link prediction.Both MFI and Inductive Matrix Completion(IMC)are not well applied with algorithmic frameworks of typical representation learning methods.Therefore,we proposed a novel semi-supervised algorithm,tri-party deep network representation learning using inductive matrix completion(TDNR).Based on inductive matrix completion algorithm,TDNR incorporates text features,the link certainty degrees of existing edges and the future link probabilities of non-existing edges into network representations.The experimental results demonstrated that TFNR outperforms other baselines on three real-world datasets.The visualizations of TDNR show that proposed algorithm is more discriminative than other unsupervised approaches.
基金Project(10JJ5057)supported by the Hunan Provincial Natural Science Foundation of China
文摘Stable and monodispersed silver nanoparticles were produced through a mild,convenient,one-pot method based on the reduction of silver nitrate in the presence of poly(amic acid) (PAA) as a stabilizer.The surface plasma band transition was monitored along with time in the reaction mixture for three sets of experiments by ultraviolet-visible spectroscopy.Analysis of the data with the Avrami equation yielded n exponent with values between 0.5 and 1.5,demonstrating three-dimensional heterogeneous nucleation and diffusion-controlled growth,accompanied by soft impingement effect.XRD and TEM analyses show a softly agglomerated polycrystalline state and a nearly spherical morphology (<50 nm) of nanoparticles.The FT-IR result indicates that the PAA molecular structure could be hardly influenced by the formation of nanoparticles.
基金Project supported by Visiting Scholar Foundation of Key Laboratory of the Resources Exploitation and Environmental Disaster Control Engineering in Southwest China (Chongqing University),Ministry of Education,China
文摘A model for liquid-gas flow （MLGF）, considering the flee movement of liquid surface, was built to simulate the wastewater velocity field and gas distribution in a full-scale Caroussel oxidation ditch with surface aeration. It was calibrated and validated by field measurement data, and the calibrated parameters and sections were selected based on both model analysis and numerical computation. The simulated velocities of MLGF were compared to that of a model for wastewater-sludge flow （MWSF）. The results show that the free liquid surface considered in MLGF improves the simulated velocity results of upper layer and surface. Moreover, distribution of gas volume fraction （GVF） simulated by MLGF was compared to dissolved oxygen （DO） measured in the oxidation ditch. It is shown that DO distribution is affected by many factors besides GVF distribution.
基金Project(2012CB026205)supported by the National Basic Research Program of ChinaProject(51238003)supported by the National Natural Science Foundation of ChinaProject(2014Y01)supported by the Transportation Department of Jiangsu Province,China
文摘According to the two-dimensional(2-D) thermo-elasticity theory, the exact elasticity solution of the simply supported laminated beams subjected to thermo-loads was studied. An analytical method was presented to obtain the temperature, displacement and stress fields in the beam. Firstly, the general solutions of temperature, displacements and stresses for a single-layered simply supported beam were obtained by solving the 2-D heat conduction equation and the 2-D elasticity equations, respectively. Then, based on the continuity of temperature, heat flux, displacements and stresses on the interface of two adjacent layers, the formulae of temperature, displacements and stresses between the lowest layer and the top layer of the beam were derived out in a recurrent manner. Finally, the unknown coefficients in the solutions were determined by the use of the upper surface and lower surface conditions of the beam. The distributions of temperature, displacement and stress in the beam were obtained by substituting these coefficients back to the recurrence formulae and the solutions. The excellent convergence of the present method has been demonstrated and the results obtained by the present method agree well with those from the finite element method. The effects of surface temperatures, thickness, layer number and material properties of the plate on the temperature distribution were discussed in detail. Numerical results reveal that the displacements and stresses monotonically increase with the increase of surface temperatures. In particular, the horizontal stresses are discontinuous at the interface.
基金Project(20180550242)supported by the Liaoning Science and Technology Plan,China。
文摘The electrodeposition of nickel-silicon carbide coatings on a copper electrode was done by mixing SiC particles in the nickel electrodeposition solution.The influence of surfactants and silicon carbide particle size on uniformity and quantity of silicon carbide particles in nickel-silicon carbide composite coatings was investigated.It was found that particle size affects the nucleation overpotential,with 40 nm silicon carbide nanoparticles more effective in promoting nickel nucleation than 500 nm particles due to an increase in active nucleation sites.In terms of surfactants,anionic surfactant sodium dodecyl sulfate(SDS)produced better dispersion of 40 nm silicon carbide particles than cationic surfactant cetyltrimethyl ammonium bromide(CTAB),but little difference was found between the two when 500 nm silicon carbide particles were used.Thus,although the suspension of silicon carbide particles can be improved and their co-deposition can be promoted with a cationic surfactant CTAB,it is less effective than an anionic surfactant SDS in terms of surface finish.
基金Projects(51471112,51611130204)supported by the National Natural Science Foundation of China
文摘Liquid nitriding of Cll0 steel was conducted in a wide range of temperatures （400-670 ℃） using a kind of chemical heat-treatments, and the hardness, mechanical and corrosion properties of the nitrided surface were evaluated. Experimental results revealed that the microstructure and phase constituents of the nitrided surface alloy are highly depended on the processing condition. When C 110 steel was subjected to liquid nitriding at 430 ℃, the nitrided layer was almost composed of a thin e-Fe2-3N layer. When C 110 steel was subjected to liquid nitriding at 640 ℃, the phase composition of the nitrided layer was greatly changed. The nitrided layer depth increased significantly with increasing the treating temperature. The liquid nitriding effectively improved the surface hardness. After liquid nitriding, the absorption energy of the treated sample decreased and the tensile strength increased by Charpy V-notch （CVN） test. But the elongation of treated sample decreased. The reason is that the nitrided layer of sample is hardened and there is brittlement by diffusion of nitrogen atom. Despite of treatment temperature, the liquid nitriding can improve the corrosion. After being nitrided at 430 ℃, the nitrided layer of the C110 steel was mainly composed by e-Fe2 3N, which has excellent corrosion resistance and high microhardness, the nitrided sample has the best corrosion resistance. After nitriding temperature over 580 ℃, especially at 680 ℃, the sample＇s surface was covered by the thick oxide layer, which has very low hardness and corrosion resistance. So, the corrosion resistance of samples is severely compromised.
基金Project(51274247) supported by the National Natural Science Foundation of ChinaProject(2014zzts177) support by the Fundamental Research Funds for the Central Universities,China
文摘Porous and dense TiNi alloys were successfully fabricated by powder metallurgy(P/M) method, and to further improve their surface biocompatibility, surface modification techniques including grind using silicon-carbide(SiC) paper, acid etching and alkali treatment were employed to produce either irregularly rough surface or micro-porous surface roughness. X-ray diffractometry(XRD), scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDX) attached to SEM were used to characterize surface structure and the Ca-P coatings. Effects of the above surface treatments on the surface morphology, apatite forming ability were systematically investigated. Results indicate that all the above surface treatments increase the apatite forming ability of TiNi alloys in varying degrees when soaked in simulated body fluid(SBF). More apatite coatings formed on TiNi samples sintered at 1050℃ and 1100℃ due to their high porosity and pure TiNi phase that is beneficial to heterogeneous nucleation. Furthermore, more uniform apatite was fabricated on the sample sintered from the mixture of Ni and Ti powders.
