Mesoporous TiO_2-B/anatase microparticles have been in-situ synthesized from K_2Ti_2O_5 without template.The TiO_2-B phase around the particle surface accelerates the diffusion of charges through the interface,while t...Mesoporous TiO_2-B/anatase microparticles have been in-situ synthesized from K_2Ti_2O_5 without template.The TiO_2-B phase around the particle surface accelerates the diffusion of charges through the interface,while the anatase phase in the core maintains the capacity stability.The heterojunction interface between the main polymorph of anatase and the trace of TiO_2-B exhibits promising lithium ion battery performance.This trace of 5%(by mass) TiO_2-B determined by Raman spectra brings the first discharge capacity of this material to 247 mA · h ·g^(-1),giving 20%improvement compared to the anatase counterpart Stability testing at 1 C reveals that the capacity maintains at 171 mA·h·^(-1),which is better than 162 mA·h·g^(-1) for single phase anatase or 159 mA·h·g^(-1) for TiO_2-B.The mesoporous TiO_2-B/anatase rnicroparticles also show superior rate performance with 100 mA·h·g^(-1) at 40 C,increased by nearly 25%as compared to pure anatase.This opens a possibility of a general design route,which can be applied to other metal oxide electrode materials for rechargeable batteries and supercapacitors.展开更多
The objectives of this study were to understand the effects of different electrical and reactor＇s parameters on the removal efficiency of air pollution and to optimize the parameters to achieve the highest removal ef...The objectives of this study were to understand the effects of different electrical and reactor＇s parameters on the removal efficiency of air pollution and to optimize the parameters to achieve the highest removal efficiency. The surface discharge was applied to dielectric barrier discharge reactors and the voltage, current, frequency and the electrode shape were employed to the reactor as main variables. In general, it has been known that the removal efficiency is decided by the applied power, which is calculated by multiplication of the applied voltage and current. However, the removal efficiency was significantly changed by the composition ratio of the applied voltage and current even though the experimental conditions were not changed with the same applied power. It means that the removal effectiveness should be affected not by the discharge power but by the applied voltage and current separately. From the experimental and statistical analysis, the discharge current was the most important factor to control the removal efficiency regardless of different types of the reactors and the frequency is not the direct function to control the removal rate.展开更多
Due to important consideration of protection against lightning surge on electrical, electronic and telecommunication equipment, it was necessary to carry out a special study to look at the performance of protective de...Due to important consideration of protection against lightning surge on electrical, electronic and telecommunication equipment, it was necessary to carry out a special study to look at the performance of protective devices. The study was testing performance of arresters on low voltage system. The activity was testing of arresters using steady state and impulse voltages. The arresters consisted of gas tube, zener diode, varistor and spark gap arresters, then it was made a cascade circuit between the varistor and spark gap arresters with a decoupling element. The decoupling elements were used air, iron and ferrite. The test yielded data of current and voltage on the tables and oscilloscope waveforms. The arresters had cut voltages early different from each other, namely the gas tube, zener diode, spark gap and varistor arresters were at the voltages of 500 V, 250 V, 1,000 V and 565 V respectively. The iron core decoupling element cascade circuit had the least oscillation among remaining cores.展开更多
Micro vapor chamber(MVC) for light emitting diodes(LEDs) can be designed and fabricated to enhance the heat dissipation efficiency and improve the reliability. In this paper, we used photoresist SU-8 and electroformin...Micro vapor chamber(MVC) for light emitting diodes(LEDs) can be designed and fabricated to enhance the heat dissipation efficiency and improve the reliability. In this paper, we used photoresist SU-8 and electroforming copper(Cu) to fabricate three kinds of wick structures, which are star, radiation and parallel ones, and the substrate is silicon with thickness of 0.5 mm. Electroforming Cu on silicon to make micro wick structure was a critical step, the ampere-hour factor was used, and accordingly the electroforming time was predicted. The composition of electroforming solution and parameters of electroforming were optimized too. After charging and packaging, thermal behavior tests were carried out to study the heat dissipation performance of MVCs. When the input power was 8 W, the parallel wick structure reached the equivalent temperature of 69.0 °C in 226 s, while the others were higher than that. The experimental results prove that the wick structures have significant influence on the heat transfer capability of MVCs.展开更多
Experimental investigation was conducted to characterize the responses of pseudo-ductile cementitious composites (PDCCs) when subjected to uniaxial and biaxial compression.The PDCCs is a class of fiber reinforced ceme...Experimental investigation was conducted to characterize the responses of pseudo-ductile cementitious composites (PDCCs) when subjected to uniaxial and biaxial compression.The PDCCs is a class of fiber reinforced cementitious composites with ultra-high ductility by using a low volume fraction (2%) of polyvinyl alcohol (PVA) fiber.Two different strength grades of PDCC were examined with cubic specimen size of 100 mm in the tests.The specimens were loaded with a servo-hydraulic jack at different stress ratios.The principle stresses and strains of the specimens were recorded,and the failure modes with various stress states were examined.The test results indicated that the ultimate strength of PDCCs increased due to the lateral confinement in the other principal stress direction,and the maximum ultimate strength occurred at the biaxial stress ratio of 0.25,which was very different from common concrete material.For the PDCC specimens,the biaxial strength may be lower than the uniaxial strength when subjected to biaxial compression with the stress ratio of 1.0,and the failure mode showed a shear-type failure because of the bridging effect of fibers.Finally,a failure criterion was proposed for PDCCs under biaxial compression.展开更多
基金Supported by the Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT 0732)the National Natural Science Foundation of China(21136004,20736002,21176113,20876073)+2 种基金NSFC-RGC(20731160614)China Postdoctoral Science Foundation(20110491407)the National Basic Research Program of China(2009CB623407,2009CB219902 and 2009CB226103)
文摘Mesoporous TiO_2-B/anatase microparticles have been in-situ synthesized from K_2Ti_2O_5 without template.The TiO_2-B phase around the particle surface accelerates the diffusion of charges through the interface,while the anatase phase in the core maintains the capacity stability.The heterojunction interface between the main polymorph of anatase and the trace of TiO_2-B exhibits promising lithium ion battery performance.This trace of 5%(by mass) TiO_2-B determined by Raman spectra brings the first discharge capacity of this material to 247 mA · h ·g^(-1),giving 20%improvement compared to the anatase counterpart Stability testing at 1 C reveals that the capacity maintains at 171 mA·h·^(-1),which is better than 162 mA·h·g^(-1) for single phase anatase or 159 mA·h·g^(-1) for TiO_2-B.The mesoporous TiO_2-B/anatase rnicroparticles also show superior rate performance with 100 mA·h·g^(-1) at 40 C,increased by nearly 25%as compared to pure anatase.This opens a possibility of a general design route,which can be applied to other metal oxide electrode materials for rechargeable batteries and supercapacitors.
文摘The objectives of this study were to understand the effects of different electrical and reactor＇s parameters on the removal efficiency of air pollution and to optimize the parameters to achieve the highest removal efficiency. The surface discharge was applied to dielectric barrier discharge reactors and the voltage, current, frequency and the electrode shape were employed to the reactor as main variables. In general, it has been known that the removal efficiency is decided by the applied power, which is calculated by multiplication of the applied voltage and current. However, the removal efficiency was significantly changed by the composition ratio of the applied voltage and current even though the experimental conditions were not changed with the same applied power. It means that the removal effectiveness should be affected not by the discharge power but by the applied voltage and current separately. From the experimental and statistical analysis, the discharge current was the most important factor to control the removal efficiency regardless of different types of the reactors and the frequency is not the direct function to control the removal rate.
文摘Due to important consideration of protection against lightning surge on electrical, electronic and telecommunication equipment, it was necessary to carry out a special study to look at the performance of protective devices. The study was testing performance of arresters on low voltage system. The activity was testing of arresters using steady state and impulse voltages. The arresters consisted of gas tube, zener diode, varistor and spark gap arresters, then it was made a cascade circuit between the varistor and spark gap arresters with a decoupling element. The decoupling elements were used air, iron and ferrite. The test yielded data of current and voltage on the tables and oscilloscope waveforms. The arresters had cut voltages early different from each other, namely the gas tube, zener diode, spark gap and varistor arresters were at the voltages of 500 V, 250 V, 1,000 V and 565 V respectively. The iron core decoupling element cascade circuit had the least oscillation among remaining cores.
基金supported by the State Key Development Program for Basic Research of China(No.2011CB013105)
文摘Micro vapor chamber(MVC) for light emitting diodes(LEDs) can be designed and fabricated to enhance the heat dissipation efficiency and improve the reliability. In this paper, we used photoresist SU-8 and electroforming copper(Cu) to fabricate three kinds of wick structures, which are star, radiation and parallel ones, and the substrate is silicon with thickness of 0.5 mm. Electroforming Cu on silicon to make micro wick structure was a critical step, the ampere-hour factor was used, and accordingly the electroforming time was predicted. The composition of electroforming solution and parameters of electroforming were optimized too. After charging and packaging, thermal behavior tests were carried out to study the heat dissipation performance of MVCs. When the input power was 8 W, the parallel wick structure reached the equivalent temperature of 69.0 °C in 226 s, while the others were higher than that. The experimental results prove that the wick structures have significant influence on the heat transfer capability of MVCs.
基金supported by the National Natural Science Foundation of China (Grant No. 51278118)the National Basic Research Program of China ("973" Program) (Grant No. 2009CB623200)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Experimental investigation was conducted to characterize the responses of pseudo-ductile cementitious composites (PDCCs) when subjected to uniaxial and biaxial compression.The PDCCs is a class of fiber reinforced cementitious composites with ultra-high ductility by using a low volume fraction (2%) of polyvinyl alcohol (PVA) fiber.Two different strength grades of PDCC were examined with cubic specimen size of 100 mm in the tests.The specimens were loaded with a servo-hydraulic jack at different stress ratios.The principle stresses and strains of the specimens were recorded,and the failure modes with various stress states were examined.The test results indicated that the ultimate strength of PDCCs increased due to the lateral confinement in the other principal stress direction,and the maximum ultimate strength occurred at the biaxial stress ratio of 0.25,which was very different from common concrete material.For the PDCC specimens,the biaxial strength may be lower than the uniaxial strength when subjected to biaxial compression with the stress ratio of 1.0,and the failure mode showed a shear-type failure because of the bridging effect of fibers.Finally,a failure criterion was proposed for PDCCs under biaxial compression.
