An in situ reaction and spray forming technique were employed in the synthesis of 2% TiB2/Si-30Al composite.The formation mechanism of TiB2 particulates was explained based on thermodynamic theory.The modification of ...An in situ reaction and spray forming technique were employed in the synthesis of 2% TiB2/Si-30Al composite.The formation mechanism of TiB2 particulates was explained based on thermodynamic theory.The modification of the primary Si in the Si-30Al alloy was interpreted in the light of the knowledge of atomic diffusion.The experimental results show that adding 2% TiB2 to the Si-30Al alloy can effectively refine the primary Si.Moreover,the coarsening and growth of primary Si phase in its semi-solid state was retarded effectively due to the existence of the TiB2 particulates.展开更多
The nanocomposite coating is obtained by electrochemical deposition of the zinc plating solution with ceria nanoparticles (mean diameter 30 nm). The effect of ceria nanoparticles on the electrodeposited zinc coating i...The nanocomposite coating is obtained by electrochemical deposition of the zinc plating solution with ceria nanoparticles (mean diameter 30 nm). The effect of ceria nanoparticles on the electrodeposited zinc coating is stu died by weight loss test, inductively copuled plasma quantometer (ICP), scanning electron microscopy (SEM) and X ray diffraction (XRD), respectively. It is found that under the same electrodeposition conditions, the corrosion resistance of the nanocomposite coating increases obviously while that of the micron composite coating only improves slightly; The ceria content of the nanocomposite coating is more than that of the micron composite coating. Ceria nanoparticles modify the surface morphology and crystal structure of the zinc matrix in correlation with the increase of corrosion resistance.展开更多
The forms of phosphorus and silicon in the natural grain sizes surface sediments of the southern Bohai Sea were studied. In sediments, the organic matter bound form of phosphorus was the main form of transferable phos...The forms of phosphorus and silicon in the natural grain sizes surface sediments of the southern Bohai Sea were studied. In sediments, the organic matter bound form of phosphorus was the main form of transferable phosphorus and ranged from 0.37 μmol/g to 1.57 μmol/g, accounting for 10.7% of the total phosphorus, others were the carbonate bound form, iron manganese oxide bound form and ion exchange able form; the transferable form of phosphorus accounted for 19.2% of the total phosphorus. Silicon’s carbonate bound form was predominant over others among its transferable forms, and content ranged from 1.55 μmol/g to 8.94 μmol/g, accounting for 0.05% of the total silicon; the total amount of transferable silicon forms accounted for only 0.12% of the total silicon. Therefore, 19.2% of the total phosphorus and 0.12% of the total silicon contained in the surface sediments of the southern Bohai Sea could participate in the biogeochemical cycling.展开更多
Supported gold nanoparticle catalysts show extraordinarily high activity in many reactions. While the relative poor thermal stability of Au nanoparticles against sintering at elevated temperatures severely limits thei...Supported gold nanoparticle catalysts show extraordinarily high activity in many reactions. While the relative poor thermal stability of Au nanoparticles against sintering at elevated temperatures severely limits their practical applications. Here atomic layer deposition （ALD） of TiO2 and Al2O3 was performed to deposit an Au/TiO2 catalyst with precise thickness con-trol, and the thermal stability was investigated. We surprisingly found that sub-nanometer-thick Al2O3 overcoat can su ciently inhibit the aggregation of Au particles up to 600 C in oxygen. On the other hand, the enhancement of Au nanoparticle stability by TiO2 overcoat is very limited. Di use reffectance infrared Fourier transform spectroscopy （DRIFTS） of CO chemisorption and X-ray photoelectron spectroscopy measurements both con rmed the ALD overcoat on Au particles surface and suggested that the presence of TiO2 and Al2O3 ALD overcoat on Au nanoparticles does not considerably change the electronic properties of Au nanoparticles. The catalytic activities of the Al2O3 overcoated Au/TiO2 catalysts in CO oxidation increased as increasing calcination temperature, which suggests that the embed-ded Au nanoparticles become more accessible for catalytic function after high temperature treatment, consistent with our DRIFTS CO chemisorption results.展开更多
The particle deposition behaviour of skim milk, water and maltodextrin in the conical section of a pilot-scale spray dryer was predicted using simple correlations for particle depositions in pipes. The predicted parti...The particle deposition behaviour of skim milk, water and maltodextrin in the conical section of a pilot-scale spray dryer was predicted using simple correlations for particle depositions in pipes. The predicted particle deposition fluxes of these materials were then compared with the measured deposition fluxes. The predicted particle deposition regimes of the spray dryer were expected to be in the diffusional and mixed (diffusional and inertial) regimes, but the experimental results suggested that the particle deposition was mainly in the inertial regime. Therefore, using the pipe correlations for predicting deposition in a pilot-scale spray dryer suggests that they do not sufficiently represent the actual deposition behaviour. This outcome indicates that a further study of particle flow patterns needs to be carried out using numerical simulations (computational fluid dynamics, CFD) in view of the additional geometrical complexity of the spray dryer.展开更多
This paper mainly investigates the effects of initial static shear stress and grain shape on the liquefaction induced large deformation of saturated sand under torsional shear.Nanjing sand,mainly composed of platy gra...This paper mainly investigates the effects of initial static shear stress and grain shape on the liquefaction induced large deformation of saturated sand under torsional shear.Nanjing sand,mainly composed of platy grains,is tested with different initial static shear stress ratio(SSR)using a hollow column torsional shear apparatus.The tests find that the saturated Nanjing sand reaches full liquefaction under the superposition of initial static shear stress and cyclic stress for both stress reversal and non-reversal cases.However,it requires a large number of loading cycles to reach full liquefaction if stress reversal does not occur.With increasing the initial static stress,the large deformation of the Nanjing sand should mainly induced by the cyclic liquefaction firstly under a smaller initial shear stress,and then it should be induced by the residual deformation failure.The critical point occurs approximately when the initial shear stress is close to the amplitude of the cyclic shear stress.Meanwhile,it shows that grain angularity increases the liquefaction resistance when the initial static shear stress is zero.A small initial static shear stress causes the larger loss of liquefaction resistance for angular sand than rounded sand.At a high initial SSR,the angular sand is more resistant to the large residual deformation failure than the rounded sand.展开更多
In granule processing industries, acquisition of particle size and shape parameters is a common procedure, and volumetric measurement is of great importance in dealing with particle sizing and gradation. To eradicate ...In granule processing industries, acquisition of particle size and shape parameters is a common procedure, and volumetric measurement is of great importance in dealing with particle sizing and gradation. To eradicate the major drawbacks with manual gauge, this paper proposes an optical approach using Back Propagation （BP） neural network to estimate the particle volume based on the two-Dimensional （2D） image information. To achieve the better network efficiency and structure simplicity, Principal Component Analysis （PCA） is adopted to reduce the dimensions of network inputs To overcome the shortcomings of generic BP network for being slow to converge and vulnerable to being trapped in local minimum, Levenberg-Marquardt （LM） algorithm is applied to achieve a higher speed and a lower error rate. The real particle data is utilized in training and testing the presented network. The experimental result suggests that the proposed neural network is capable of estimating aggregate volume with satisfactory precision and superior to the generic BP network in terms of perforxnance capacity.展开更多
基金Project(707007)supported by the Cultivation Fund of the Key Scientific and Technical Innovation,ChinaProject(2093040)supported by Beijing Municipal Natural Science Foundation,China
文摘An in situ reaction and spray forming technique were employed in the synthesis of 2% TiB2/Si-30Al composite.The formation mechanism of TiB2 particulates was explained based on thermodynamic theory.The modification of the primary Si in the Si-30Al alloy was interpreted in the light of the knowledge of atomic diffusion.The experimental results show that adding 2% TiB2 to the Si-30Al alloy can effectively refine the primary Si.Moreover,the coarsening and growth of primary Si phase in its semi-solid state was retarded effectively due to the existence of the TiB2 particulates.
文摘The nanocomposite coating is obtained by electrochemical deposition of the zinc plating solution with ceria nanoparticles (mean diameter 30 nm). The effect of ceria nanoparticles on the electrodeposited zinc coating is stu died by weight loss test, inductively copuled plasma quantometer (ICP), scanning electron microscopy (SEM) and X ray diffraction (XRD), respectively. It is found that under the same electrodeposition conditions, the corrosion resistance of the nanocomposite coating increases obviously while that of the micron composite coating only improves slightly; The ceria content of the nanocomposite coating is more than that of the micron composite coating. Ceria nanoparticles modify the surface morphology and crystal structure of the zinc matrix in correlation with the increase of corrosion resistance.
文摘The forms of phosphorus and silicon in the natural grain sizes surface sediments of the southern Bohai Sea were studied. In sediments, the organic matter bound form of phosphorus was the main form of transferable phosphorus and ranged from 0.37 μmol/g to 1.57 μmol/g, accounting for 10.7% of the total phosphorus, others were the carbonate bound form, iron manganese oxide bound form and ion exchange able form; the transferable form of phosphorus accounted for 19.2% of the total phosphorus. Silicon’s carbonate bound form was predominant over others among its transferable forms, and content ranged from 1.55 μmol/g to 8.94 μmol/g, accounting for 0.05% of the total silicon; the total amount of transferable silicon forms accounted for only 0.12% of the total silicon. Therefore, 19.2% of the total phosphorus and 0.12% of the total silicon contained in the surface sediments of the southern Bohai Sea could participate in the biogeochemical cycling.
文摘Supported gold nanoparticle catalysts show extraordinarily high activity in many reactions. While the relative poor thermal stability of Au nanoparticles against sintering at elevated temperatures severely limits their practical applications. Here atomic layer deposition （ALD） of TiO2 and Al2O3 was performed to deposit an Au/TiO2 catalyst with precise thickness con-trol, and the thermal stability was investigated. We surprisingly found that sub-nanometer-thick Al2O3 overcoat can su ciently inhibit the aggregation of Au particles up to 600 C in oxygen. On the other hand, the enhancement of Au nanoparticle stability by TiO2 overcoat is very limited. Di use reffectance infrared Fourier transform spectroscopy （DRIFTS） of CO chemisorption and X-ray photoelectron spectroscopy measurements both con rmed the ALD overcoat on Au particles surface and suggested that the presence of TiO2 and Al2O3 ALD overcoat on Au nanoparticles does not considerably change the electronic properties of Au nanoparticles. The catalytic activities of the Al2O3 overcoated Au/TiO2 catalysts in CO oxidation increased as increasing calcination temperature, which suggests that the embed-ded Au nanoparticles become more accessible for catalytic function after high temperature treatment, consistent with our DRIFTS CO chemisorption results.
文摘The particle deposition behaviour of skim milk, water and maltodextrin in the conical section of a pilot-scale spray dryer was predicted using simple correlations for particle depositions in pipes. The predicted particle deposition fluxes of these materials were then compared with the measured deposition fluxes. The predicted particle deposition regimes of the spray dryer were expected to be in the diffusional and mixed (diffusional and inertial) regimes, but the experimental results suggested that the particle deposition was mainly in the inertial regime. Therefore, using the pipe correlations for predicting deposition in a pilot-scale spray dryer suggests that they do not sufficiently represent the actual deposition behaviour. This outcome indicates that a further study of particle flow patterns needs to be carried out using numerical simulations (computational fluid dynamics, CFD) in view of the additional geometrical complexity of the spray dryer.
基金supported by the National Natural Science Foundation of China(Nos.51778290,51778386)the National Science Fund for Distinguished Young Scholars(No.51725802)the Natural Science Foundation of Jiangsu High School(No.16KJA560001)。
文摘This paper mainly investigates the effects of initial static shear stress and grain shape on the liquefaction induced large deformation of saturated sand under torsional shear.Nanjing sand,mainly composed of platy grains,is tested with different initial static shear stress ratio(SSR)using a hollow column torsional shear apparatus.The tests find that the saturated Nanjing sand reaches full liquefaction under the superposition of initial static shear stress and cyclic stress for both stress reversal and non-reversal cases.However,it requires a large number of loading cycles to reach full liquefaction if stress reversal does not occur.With increasing the initial static stress,the large deformation of the Nanjing sand should mainly induced by the cyclic liquefaction firstly under a smaller initial shear stress,and then it should be induced by the residual deformation failure.The critical point occurs approximately when the initial shear stress is close to the amplitude of the cyclic shear stress.Meanwhile,it shows that grain angularity increases the liquefaction resistance when the initial static shear stress is zero.A small initial static shear stress causes the larger loss of liquefaction resistance for angular sand than rounded sand.At a high initial SSR,the angular sand is more resistant to the large residual deformation failure than the rounded sand.
基金Supported by Ningbo Natural Science Foundation (No. 2006A610016)Foundation of Ministry of Education for Returned Overseas Students & Scholars (SRF for ROCS, SEM. No. 2006699)
文摘In granule processing industries, acquisition of particle size and shape parameters is a common procedure, and volumetric measurement is of great importance in dealing with particle sizing and gradation. To eradicate the major drawbacks with manual gauge, this paper proposes an optical approach using Back Propagation （BP） neural network to estimate the particle volume based on the two-Dimensional （2D） image information. To achieve the better network efficiency and structure simplicity, Principal Component Analysis （PCA） is adopted to reduce the dimensions of network inputs To overcome the shortcomings of generic BP network for being slow to converge and vulnerable to being trapped in local minimum, Levenberg-Marquardt （LM） algorithm is applied to achieve a higher speed and a lower error rate. The real particle data is utilized in training and testing the presented network. The experimental result suggests that the proposed neural network is capable of estimating aggregate volume with satisfactory precision and superior to the generic BP network in terms of perforxnance capacity.
