The metallic states of ultrafine amorphous alloy particles CoB, CoPB and Co metal were studied by using JCP, XPS and ethylene hydrogenation reaction test. It is shown that Co component on surface of CoB and CoPB amorp...The metallic states of ultrafine amorphous alloy particles CoB, CoPB and Co metal were studied by using JCP, XPS and ethylene hydrogenation reaction test. It is shown that Co component on surface of CoB and CoPB amorphous alloy particles is in electron-deficient state, which leads to the increase of irreversible absorption of ethylene,and results in the decrease of the active site number. Hence the catalytic activity of CoB and CoPB catalysts for ethylenc hydrogenation is lower than that of metallic Co.展开更多
The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructi...The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructive particle damping-phononic crystal vibration isolator is proposed herein,which uses the particle damping vibration absorption technology and bandgap vibration control theory.The vibration reduction performance of the NOPD-PCVI was analyzed from the perspective of vibration control.The paper explores the structure-borne noise reduction performance of the NOPD-PCVIs installed on different bridge structures under varying service conditions encountered in practical engineering applications.The load transferred to the bridge is obtained from a coupled train-FST-bridge analytical model considering the different structural parameters of bridges.The vibration responses are obtained using the finite element method,while the structural noise radiation is simulated using the frequency-domain boundary element method.Using the particle swarm optimization algorithm,the parameters of the NOPD-PCVI are optimized so that its frequency bandgap matches the dominant bridge structural noise frequency range.The noise reduction performance of the NOPD-PCVIs is compared to the steel-spring isolation under different service conditions.展开更多
To improve the magneto-rheological (MR) properties of magneto-rheological fluids, self-made amorphous alloy particles, the composition of which was Fe76Cr2Mo2Sn2P10B2C2Si4, were used as the disperse phase to replace t...To improve the magneto-rheological (MR) properties of magneto-rheological fluids, self-made amorphous alloy particles, the composition of which was Fe76Cr2Mo2Sn2P10B2C2Si4, were used as the disperse phase to replace traditional carbonyl iron (CI) particles to prepare amorphous based magneto-rheological fluid (AMRF). Soft magnetic properties and densities of the amorphous particles and the CI particles were tested and compared. The results indicate the amorphous particles present a lower density but larger magnetization intensity and larger permeability at lower field levels. Properties of the AMRF with 20% particles in volume fraction were tested and compared with the CI based MR fluid (CMRF). The AMRF presents a saturation yield stress of 41 kPa at ~227 kA/m and a sedimentation ratio of 80%. The results indicate the magneto-rheological fluid based on amorphous micro-particles has better MR properties and sedimentation stability than that based on CI particles at lower field levels (0-200 kA/m).展开更多
AZ61 alloys with different levels of Al5Ti1B master alloy additions were prepared by conventional casting method.The effects of Al5Ti1B contents and holding time on microstructures and microhardness of AZ61 alloys wer...AZ61 alloys with different levels of Al5Ti1B master alloy additions were prepared by conventional casting method.The effects of Al5Ti1B contents and holding time on microstructures and microhardness of AZ61 alloys were studied by XRD,OM and microhardness testing techniques.The results show that when the addition level of Al5Ti1B master alloy is less than 0.5%(mass fraction),the average grain size of the alloys decreases with the increase of Al5Ti1B content at the same holding time.But the grain size increases somewhat with further addition of Al5Ti1B.The average grain size of the alloys decreases with the increase of the holding time as it is less than 30 min at the same addition level of Al5Ti1B.It is considered that TiB2 particles can serve as the heterogeneous nucleation sites ofα-Mg during solidification,and heterogeneous nucleation is the main reason for the grain refinement of AZ61 alloys.The microhardness of the refined AZ61 alloys with 1.0%Al5Ti1B addition is increased by about 8%.展开更多
The effect of different molar ratios of Y2O3 and Y（NO3）3 on the microstructure and electrical response of ZnO-Bi203-based varistor ceramics sintered at 1 000 ℃ was investigated, and the mechanism by which this dopi...The effect of different molar ratios of Y2O3 and Y（NO3）3 on the microstructure and electrical response of ZnO-Bi203-based varistor ceramics sintered at 1 000 ℃ was investigated, and the mechanism by which this doping improves the electrical characteristics of ZnO-Bi203-based varistor ceramics was discussed. With increasing amounts of Y（NO3）3 or Y2O3 in the starting composition, Y2O3, Sb204 and Y-containing Bi-rich phase form, and the average grain size significantly decreases. The average grain size significantly decreases as the contents of rare earth compounds of Y（NO3）3 or Y2O3 increase. The maximum value of the nonlinear coefficient is found at 0.16% Y（NO3）3 or 0.02% YaO3 （molar fraction） doped varistor ceramics, and there is an increase of 122% or 35% compared with the varistor ceramics without Y（NO3）3 or Y2O3. The threshold voltage VT of Y（NO3）3 and Y2O3 reaches at 1 460 V/mm and 1 035 V/ram, respectively. The results also show that varistor sample doped with Y（NO3）3 has a remarkably more homogeneous and denser microstructure in comparison to the sample doped with Y2O3.展开更多
The preparation process of amorphous nanometer boron powders through combustion synthesis was investigated, and the effects of the reactant ratio, the heating agent and the milling rate on the activity and particle si...The preparation process of amorphous nanometer boron powders through combustion synthesis was investigated, and the effects of the reactant ratio, the heating agent and the milling rate on the activity and particle size of amorphous boron powders were studied. The results show that the boron powders exist in the form of an amorphous phase which has the crystallinity lower than 30.4%, and the panicle size of boron powder decreases with an increase of the high-energy ball milling rate. The purity of amorphous boron powder is 94.8% and panicle sizes are much smaller than 100 nm when the mass ratio of B2O3/Mg/KClO3 is 100：105：17 and the ball milling time is 20 min with the milling rate of 300 r/min. At the same time, the amorphous boron nano-fibers appear in the boron powders.展开更多
Crystallization is used to produce vast quantities of materials. For several applications, continuous crystallization is often the best operation mode because it is able to reproduce better crystal size distributions ...Crystallization is used to produce vast quantities of materials. For several applications, continuous crystallization is often the best operation mode because it is able to reproduce better crystal size distributions than other operation modes. Nonlinear oscillation in continuous industrial crystallization processes is a well-known phenomenon leading to practical difficulties such that control actions are necessary. Nonlinear oscillation is a consequence of the highly nonlinear kinetics, different feedbacks between the variables and elementary processes taking place in crystallizers units, and the non-equilibrium thermodynamic operation. In this paper the control of a continuous crystallizer model that displays oscillatory behavior is addressed via two practical robust control approaches： （i） modeling error compensation, and （ii） integral high order sliding mode control. The controller designs are based on the reduced-order model representation of the population balance equations resulting after the application of the method of moments. Numerical simulations show good closed-loop performance and robustness properties展开更多
文摘The metallic states of ultrafine amorphous alloy particles CoB, CoPB and Co metal were studied by using JCP, XPS and ethylene hydrogenation reaction test. It is shown that Co component on surface of CoB and CoPB amorphous alloy particles is in electron-deficient state, which leads to the increase of irreversible absorption of ethylene,and results in the decrease of the active site number. Hence the catalytic activity of CoB and CoPB catalysts for ethylenc hydrogenation is lower than that of metallic Co.
基金Project(51978585)supported by the National Natural Science Foundation,ChinaProject(2022YFB2603404)supported by the National Key Research and Development Program,China+1 种基金Project(U1734207)supported by the High-speed Rail Joint Fund Key Projects of Basic Research,ChinaProject(2023NSFSC1975)supported by the Sichuan Nature and Science Foundation Innovation Research Group Project,China。
文摘The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructive particle damping-phononic crystal vibration isolator is proposed herein,which uses the particle damping vibration absorption technology and bandgap vibration control theory.The vibration reduction performance of the NOPD-PCVI was analyzed from the perspective of vibration control.The paper explores the structure-borne noise reduction performance of the NOPD-PCVIs installed on different bridge structures under varying service conditions encountered in practical engineering applications.The load transferred to the bridge is obtained from a coupled train-FST-bridge analytical model considering the different structural parameters of bridges.The vibration responses are obtained using the finite element method,while the structural noise radiation is simulated using the frequency-domain boundary element method.Using the particle swarm optimization algorithm,the parameters of the NOPD-PCVI are optimized so that its frequency bandgap matches the dominant bridge structural noise frequency range.The noise reduction performance of the NOPD-PCVIs is compared to the steel-spring isolation under different service conditions.
基金Project (51108062) supported by the National Natural Science Foundation of ChinaProject(20100471446) supported by the China Postdoctoral Science Foundation
文摘To improve the magneto-rheological (MR) properties of magneto-rheological fluids, self-made amorphous alloy particles, the composition of which was Fe76Cr2Mo2Sn2P10B2C2Si4, were used as the disperse phase to replace traditional carbonyl iron (CI) particles to prepare amorphous based magneto-rheological fluid (AMRF). Soft magnetic properties and densities of the amorphous particles and the CI particles were tested and compared. The results indicate the amorphous particles present a lower density but larger magnetization intensity and larger permeability at lower field levels. Properties of the AMRF with 20% particles in volume fraction were tested and compared with the CI based MR fluid (CMRF). The AMRF presents a saturation yield stress of 41 kPa at ~227 kA/m and a sedimentation ratio of 80%. The results indicate the magneto-rheological fluid based on amorphous micro-particles has better MR properties and sedimentation stability than that based on CI particles at lower field levels (0-200 kA/m).
基金Project(2010RFQXG117)supported by the Special Fund for Technological Innovation Program of Harbin,China
文摘AZ61 alloys with different levels of Al5Ti1B master alloy additions were prepared by conventional casting method.The effects of Al5Ti1B contents and holding time on microstructures and microhardness of AZ61 alloys were studied by XRD,OM and microhardness testing techniques.The results show that when the addition level of Al5Ti1B master alloy is less than 0.5%(mass fraction),the average grain size of the alloys decreases with the increase of Al5Ti1B content at the same holding time.But the grain size increases somewhat with further addition of Al5Ti1B.The average grain size of the alloys decreases with the increase of the holding time as it is less than 30 min at the same addition level of Al5Ti1B.It is considered that TiB2 particles can serve as the heterogeneous nucleation sites ofα-Mg during solidification,and heterogeneous nucleation is the main reason for the grain refinement of AZ61 alloys.The microhardness of the refined AZ61 alloys with 1.0%Al5Ti1B addition is increased by about 8%.
基金Project(BK2011243) supported by the Natural Science Foundation of Jiangsu Province, ChinaProject(EIPE11204) supported by the State Key Laboratory of Electrical Insulation and Power Equipment, China+4 种基金Project(KF201104) supported by the State Key Laboratory of New Ceramic and Fine Processing, ChinaProject(KFJJ201105) supported by the Opening Program of State key Laboratory of Electronic Thin Films and Integrated Devices, ChinaProject(2011-22) supported by the State Key Laboratory of Inorganic Synthesis and Preparative Chemistry of Jilin University, ChinaProject(10KJD430002) supported by the Universities Natural Science Research Project of Jiangsu Province, ChinaProject(11JDG084) supported by the Research Foundation of Jiangsu University, China
文摘The effect of different molar ratios of Y2O3 and Y（NO3）3 on the microstructure and electrical response of ZnO-Bi203-based varistor ceramics sintered at 1 000 ℃ was investigated, and the mechanism by which this doping improves the electrical characteristics of ZnO-Bi203-based varistor ceramics was discussed. With increasing amounts of Y（NO3）3 or Y2O3 in the starting composition, Y2O3, Sb204 and Y-containing Bi-rich phase form, and the average grain size significantly decreases. The average grain size significantly decreases as the contents of rare earth compounds of Y（NO3）3 or Y2O3 increase. The maximum value of the nonlinear coefficient is found at 0.16% Y（NO3）3 or 0.02% YaO3 （molar fraction） doped varistor ceramics, and there is an increase of 122% or 35% compared with the varistor ceramics without Y（NO3）3 or Y2O3. The threshold voltage VT of Y（NO3）3 and Y2O3 reaches at 1 460 V/mm and 1 035 V/ram, respectively. The results also show that varistor sample doped with Y（NO3）3 has a remarkably more homogeneous and denser microstructure in comparison to the sample doped with Y2O3.
基金Project(51002025) supported by the National Natural Science Foundation of China
文摘The preparation process of amorphous nanometer boron powders through combustion synthesis was investigated, and the effects of the reactant ratio, the heating agent and the milling rate on the activity and particle size of amorphous boron powders were studied. The results show that the boron powders exist in the form of an amorphous phase which has the crystallinity lower than 30.4%, and the panicle size of boron powder decreases with an increase of the high-energy ball milling rate. The purity of amorphous boron powder is 94.8% and panicle sizes are much smaller than 100 nm when the mass ratio of B2O3/Mg/KClO3 is 100：105：17 and the ball milling time is 20 min with the milling rate of 300 r/min. At the same time, the amorphous boron nano-fibers appear in the boron powders.
文摘Crystallization is used to produce vast quantities of materials. For several applications, continuous crystallization is often the best operation mode because it is able to reproduce better crystal size distributions than other operation modes. Nonlinear oscillation in continuous industrial crystallization processes is a well-known phenomenon leading to practical difficulties such that control actions are necessary. Nonlinear oscillation is a consequence of the highly nonlinear kinetics, different feedbacks between the variables and elementary processes taking place in crystallizers units, and the non-equilibrium thermodynamic operation. In this paper the control of a continuous crystallizer model that displays oscillatory behavior is addressed via two practical robust control approaches： （i） modeling error compensation, and （ii） integral high order sliding mode control. The controller designs are based on the reduced-order model representation of the population balance equations resulting after the application of the method of moments. Numerical simulations show good closed-loop performance and robustness properties
