A rectangular finite element for laminated plate with bonded and/or embedded piezoelectric sensors and actuators is developed based on the variational principle and the first order shear deformation theory. The elemen...A rectangular finite element for laminated plate with bonded and/or embedded piezoelectric sensors and actuators is developed based on the variational principle and the first order shear deformation theory. The element has four-node, 20-degrees-of-freedom with one potential degree of freedom for each piezoelectric layer to represent the piezoelectric behavior. The higher order derivation of deflection is obtained by using the normal rotation expressions to take the effects of transverse shear deformation into considerations. The finite element can accurately simulate the deformation of both thin and moderately thick plates. A Fortran program is written and a number of benchmark tests are exercised to verify its effectiveness. Results are compared well with the existing data. The unbalanced composite with piezoelectric layers is then analyzed by using the model. Results show that the changes of the ratio between the thickness of positive angle layers and the negative angle layers have an effect on the deformation of the structure under the same electric loading.展开更多
Nanostructured MnO2/CNT composite was synthesized by a soft template approach in the presence of Pluronic P123 surfactant. The product was characterized by X-ray diffraction, thermogravimetric and differential thermal...Nanostructured MnO2/CNT composite was synthesized by a soft template approach in the presence of Pluronic P123 surfactant. The product was characterized by X-ray diffraction, thermogravimetric and differential thermal analyses, Fourier transformed infrared spectroscopy and high-resolution transmission electron microscopy. The results show that the sample consists of poor crystalline α-MnO2 nanorods with a diameter of about 10 nm and a length of 30-50 nm, which absorb on the carbon nanotubes. The electrochemical properties of the product as cathode material for Li-MnO2 cell are evaluated by galvanostatic charge-discharge and electrochemical impedance spectroscopy （EIS）. Compared with pure MnO2 electrode, the MnO2/CNT composite delivers a much larger initial capacity of 275.3 mA-h/g and better rate and cycling performance.展开更多
The pore structures and electrochemical performances of mesoporous carbons prepared by silica sol template method as electrode material for supercapacitor were investigated. The mean pore size and mass specific capaci...The pore structures and electrochemical performances of mesoporous carbons prepared by silica sol template method as electrode material for supercapacitor were investigated. The mean pore size and mass specific capacitance of the mesoporous carbons increase with the increase of mass ratio of silica sol to carbon source （glucose）. A modified template method, combining silica sol template method and ZnCl2 chemical activation method, was proposed to improve the mass specific capacitance of the mesoporous carbon with an improved BET surface area. The correlation of rate capability and pore structure was studied by constant current discharge and electrochemical impedance spectroscopy. A commercially available microporous carbon was used for comparison. The result shows that mesoporous carbon with a larger pore size displays a higher rate capability. Mesoporous carbon synthesized by modified template method has both high mass specific capacitance and good rate capability.展开更多
A systematic laboratory study was conducted on current efficiency and corrosion obtained in cryolite-alumina melts with SnO2-Sb203-CuO ceramic inert anodes. The current efficiency （CE） was determined by measuring th...A systematic laboratory study was conducted on current efficiency and corrosion obtained in cryolite-alumina melts with SnO2-Sb203-CuO ceramic inert anodes. The current efficiency （CE） was determined by measuring the total amount of oxygen evolved at the anode and was found to be ~ 95%. The influence of operating parameters （inter-elec- trode distance, temperature and current density） was evaluated. The quantitative interdependencies as well as the ranges of CE optima[ values were established （2-3 cm, 940-960 ℃ and 0.7-0.8 A.cm 2）. The corrosion process of these anodes was evaluated by the mass loss method. The evaluation also took care of the corrosion data, as the prob- lem of the anode corrosion appeared to be the main obstacle for the use of those anodes in the commercial cells.Low-ering of the ACD up to 2 cm did not aggravate anode corrosion.展开更多
Some commercially available solar panels with very high efficiencies for terrestrial photovoltaic applications are based on the amorphous silicon on crystalline silicon material system. This type ofheterostructure has...Some commercially available solar panels with very high efficiencies for terrestrial photovoltaic applications are based on the amorphous silicon on crystalline silicon material system. This type ofheterostructure has more than 40 years＇ old history. The early development of the technology and the results, obtained in the last years with this type of solar cell are reviewed. In particular it is demonstrated why the physical understanding of the interface properties and band-structure was important for the development of high efficiency solar cells.展开更多
An investigation was performed on the suitability of carbon materials, metallic lead and its alloys as substrates for zinc negative electrode in acid PbO2-Zn single flow batteries. The zinc deposition process was carr...An investigation was performed on the suitability of carbon materials, metallic lead and its alloys as substrates for zinc negative electrode in acid PbO2-Zn single flow batteries. The zinc deposition process was carried out in the mediumofl mol.L 1H2SO4 at room temperature. No maximum current appears on the potentiostatic current transients for the zinc deposition on lead and its alloys. With increasing overpotential, the progressive nucleation turns to be a 3D-instantaneous nucleation process for the resin-graphite composite. Hydrogen evolution on the graphite composite is effectively suppressed with the doping of a polymer resin. The hydrogen evolution reaction on the lead is relatively weak, while on the lead alloys, it becomes serious to a certain degree. Although the ex- change current density of zinc deposition and dissolution process on the graphite composite is relatively low, the zinc corrosion is weakened to a great extent. With the increase of deposition time, zinc deposits are more compact. The cyclings of zinc galvanostatic charge-discharge on the graphite composite provide more than 90% of coulombic and 80% of energy efficiencies, and exhibit superior cycling stability during the first 10 cycles.展开更多
During 1970s, the residential remains of the Yangshao Period were discovered at the Dadiwan site in Qin＇an County, Gansu Province, China. With carbon-14 dating, scanning electron microscope （SEM）, thermal expansion...During 1970s, the residential remains of the Yangshao Period were discovered at the Dadiwan site in Qin＇an County, Gansu Province, China. With carbon-14 dating, scanning electron microscope （SEM）, thermal expansion analyzer, polarizing microscope （PLM）, and X ray diffraction （XRD）, the microstructures and chemical compositions of the pottery shard, floor materials of the housing site, kunkur, calcined kunkur, ginger nut （calcium concretion） from the Dadiwan site were analyzed and re- searched. Analysis and simulation tests were also carried out to study the hydratability of calcined ginger nut and calcined kunkur, and the manufacturing process of the residential floors. The research shows that the floor was made of a light concrete formed by the mixture of aggregate of calcinated ginger nut （locally deposited）, red clay and kunkur. The dicalcium silicate （C2S） from the floor material of the housing site is one of the main constituents of modem cement, and the floor is also similar to modem concrete in nature. Therefore, the floor material of the housing site at the Dadiwan site was the earliest man-made concrete in the world ever discovered.展开更多
The sacrificial templates used in galvanic replacement reactions dictate the properties of the hollow metal nanostructures formed. Here, we demonstrate that substrate-based Au-Ag nanoshells with radically altered prop...The sacrificial templates used in galvanic replacement reactions dictate the properties of the hollow metal nanostructures formed. Here, we demonstrate that substrate-based Au-Ag nanoshells with radically altered properties are obtained by merely coating silver templates with an ultrathin layer of gold prior to their insertion into the reaction vessel. The so-formed nanoshells exhibit much smoother surfaces, a higher degree of crystallinity and are far more robust. Dealloying the nanoshells results in the first demonstration of substrate-based nanocages. Such cages exhibit a well-defined pattern of geometric openings in directions corresponding to the {111}-facets of the starting template material. The ability to engineer the cage geometry through adjustments to the orientational relationship between the crystal structure of the starting template and that of underlying substrate is demonstrated. Together these discoveries provide the framework to advance our understanding of the mechanisms governing substrate- based galvanic replacement reactions.展开更多
Anodic aluminum oxide （AAO） with highly ordered nanoscale pores which are monodisperse and mutually parallel can be produced through a self-organized electrochemical process. Subsequent deposition of materials into ...Anodic aluminum oxide （AAO） with highly ordered nanoscale pores which are monodisperse and mutually parallel can be produced through a self-organized electrochemical process. Subsequent deposition of materials into the nanopores produces AA0 embedded nanowire arrays. Whilst the templates can be further removed to obtain free individual nanowires, the em- bedded nanowires form an interesting nanocomposite structure. Recent research activities on the fabrication and characteriza- tion of AAO template based magnetic nanowires are reviewed in this article. Studies of specific systems are given as an exam- ple of the research in the area.展开更多
Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at ...Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates elements of applied physics and chemistry. With significant media attention focused on nanoscience and nanotechnology in recent years, materials science has been propelled to the forefront at many universities. Materials science encompasses various classes of materials, including electronic materials, functional ceramics, magnesium, material and processes for flat-panel displays, eco/environmental materials, sustainable energy materials, transportation materials, electronic packaging materials, etc.展开更多
文摘A rectangular finite element for laminated plate with bonded and/or embedded piezoelectric sensors and actuators is developed based on the variational principle and the first order shear deformation theory. The element has four-node, 20-degrees-of-freedom with one potential degree of freedom for each piezoelectric layer to represent the piezoelectric behavior. The higher order derivation of deflection is obtained by using the normal rotation expressions to take the effects of transverse shear deformation into considerations. The finite element can accurately simulate the deformation of both thin and moderately thick plates. A Fortran program is written and a number of benchmark tests are exercised to verify its effectiveness. Results are compared well with the existing data. The unbalanced composite with piezoelectric layers is then analyzed by using the model. Results show that the changes of the ratio between the thickness of positive angle layers and the negative angle layers have an effect on the deformation of the structure under the same electric loading.
基金Projects(21071153,20976198)supported by the National Natural Science Foundation of China
文摘Nanostructured MnO2/CNT composite was synthesized by a soft template approach in the presence of Pluronic P123 surfactant. The product was characterized by X-ray diffraction, thermogravimetric and differential thermal analyses, Fourier transformed infrared spectroscopy and high-resolution transmission electron microscopy. The results show that the sample consists of poor crystalline α-MnO2 nanorods with a diameter of about 10 nm and a length of 30-50 nm, which absorb on the carbon nanotubes. The electrochemical properties of the product as cathode material for Li-MnO2 cell are evaluated by galvanostatic charge-discharge and electrochemical impedance spectroscopy （EIS）. Compared with pure MnO2 electrode, the MnO2/CNT composite delivers a much larger initial capacity of 275.3 mA-h/g and better rate and cycling performance.
文摘The pore structures and electrochemical performances of mesoporous carbons prepared by silica sol template method as electrode material for supercapacitor were investigated. The mean pore size and mass specific capacitance of the mesoporous carbons increase with the increase of mass ratio of silica sol to carbon source （glucose）. A modified template method, combining silica sol template method and ZnCl2 chemical activation method, was proposed to improve the mass specific capacitance of the mesoporous carbon with an improved BET surface area. The correlation of rate capability and pore structure was studied by constant current discharge and electrochemical impedance spectroscopy. A commercially available microporous carbon was used for comparison. The result shows that mesoporous carbon with a larger pore size displays a higher rate capability. Mesoporous carbon synthesized by modified template method has both high mass specific capacitance and good rate capability.
文摘A systematic laboratory study was conducted on current efficiency and corrosion obtained in cryolite-alumina melts with SnO2-Sb203-CuO ceramic inert anodes. The current efficiency （CE） was determined by measuring the total amount of oxygen evolved at the anode and was found to be ~ 95%. The influence of operating parameters （inter-elec- trode distance, temperature and current density） was evaluated. The quantitative interdependencies as well as the ranges of CE optima[ values were established （2-3 cm, 940-960 ℃ and 0.7-0.8 A.cm 2）. The corrosion process of these anodes was evaluated by the mass loss method. The evaluation also took care of the corrosion data, as the prob- lem of the anode corrosion appeared to be the main obstacle for the use of those anodes in the commercial cells.Low-ering of the ACD up to 2 cm did not aggravate anode corrosion.
文摘Some commercially available solar panels with very high efficiencies for terrestrial photovoltaic applications are based on the amorphous silicon on crystalline silicon material system. This type ofheterostructure has more than 40 years＇ old history. The early development of the technology and the results, obtained in the last years with this type of solar cell are reviewed. In particular it is demonstrated why the physical understanding of the interface properties and band-structure was important for the development of high efficiency solar cells.
基金Supported by the National Basic Research Program(973 Program)of China(2010CB227201)the State Key Program of National Natural Science of China(21236003)+2 种基金the National Natural Science Foundation of China(21476022)the Fundamental Research Funds for the Central Universities(JD1515 and YS1406)Beijing Higher Education Young Elite Teacher Project(YETP0509)
文摘An investigation was performed on the suitability of carbon materials, metallic lead and its alloys as substrates for zinc negative electrode in acid PbO2-Zn single flow batteries. The zinc deposition process was carried out in the mediumofl mol.L 1H2SO4 at room temperature. No maximum current appears on the potentiostatic current transients for the zinc deposition on lead and its alloys. With increasing overpotential, the progressive nucleation turns to be a 3D-instantaneous nucleation process for the resin-graphite composite. Hydrogen evolution on the graphite composite is effectively suppressed with the doping of a polymer resin. The hydrogen evolution reaction on the lead is relatively weak, while on the lead alloys, it becomes serious to a certain degree. Although the ex- change current density of zinc deposition and dissolution process on the graphite composite is relatively low, the zinc corrosion is weakened to a great extent. With the increase of deposition time, zinc deposits are more compact. The cyclings of zinc galvanostatic charge-discharge on the graphite composite provide more than 90% of coulombic and 80% of energy efficiencies, and exhibit superior cycling stability during the first 10 cycles.
文摘During 1970s, the residential remains of the Yangshao Period were discovered at the Dadiwan site in Qin＇an County, Gansu Province, China. With carbon-14 dating, scanning electron microscope （SEM）, thermal expansion analyzer, polarizing microscope （PLM）, and X ray diffraction （XRD）, the microstructures and chemical compositions of the pottery shard, floor materials of the housing site, kunkur, calcined kunkur, ginger nut （calcium concretion） from the Dadiwan site were analyzed and re- searched. Analysis and simulation tests were also carried out to study the hydratability of calcined ginger nut and calcined kunkur, and the manufacturing process of the residential floors. The research shows that the floor was made of a light concrete formed by the mixture of aggregate of calcinated ginger nut （locally deposited）, red clay and kunkur. The dicalcium silicate （C2S） from the floor material of the housing site is one of the main constituents of modem cement, and the floor is also similar to modem concrete in nature. Therefore, the floor material of the housing site at the Dadiwan site was the earliest man-made concrete in the world ever discovered.
基金This work is funded by the National Science Foundation （NSF） （No. DMR-1053416） The Faculty Early Career Development （CAREER） Award to SN. The authors also acknowledge the expertise of Dr. F. Monson （Technical Director, Center for Microanalysis, Imaging, Research and Training, West Chester University）. The work has benefited from the facilities available through Temple University＇s Material Research Facility （MRF） and the Penn Regional Nanotechnology Facility. K.D.G. acknowledges support received through a Temple University Graduate Student Fellowship.
文摘The sacrificial templates used in galvanic replacement reactions dictate the properties of the hollow metal nanostructures formed. Here, we demonstrate that substrate-based Au-Ag nanoshells with radically altered properties are obtained by merely coating silver templates with an ultrathin layer of gold prior to their insertion into the reaction vessel. The so-formed nanoshells exhibit much smoother surfaces, a higher degree of crystallinity and are far more robust. Dealloying the nanoshells results in the first demonstration of substrate-based nanocages. Such cages exhibit a well-defined pattern of geometric openings in directions corresponding to the {111}-facets of the starting template material. The ability to engineer the cage geometry through adjustments to the orientational relationship between the crystal structure of the starting template and that of underlying substrate is demonstrated. Together these discoveries provide the framework to advance our understanding of the mechanisms governing substrate- based galvanic replacement reactions.
文摘Anodic aluminum oxide （AAO） with highly ordered nanoscale pores which are monodisperse and mutually parallel can be produced through a self-organized electrochemical process. Subsequent deposition of materials into the nanopores produces AA0 embedded nanowire arrays. Whilst the templates can be further removed to obtain free individual nanowires, the em- bedded nanowires form an interesting nanocomposite structure. Recent research activities on the fabrication and characteriza- tion of AAO template based magnetic nanowires are reviewed in this article. Studies of specific systems are given as an exam- ple of the research in the area.
文摘Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates elements of applied physics and chemistry. With significant media attention focused on nanoscience and nanotechnology in recent years, materials science has been propelled to the forefront at many universities. Materials science encompasses various classes of materials, including electronic materials, functional ceramics, magnesium, material and processes for flat-panel displays, eco/environmental materials, sustainable energy materials, transportation materials, electronic packaging materials, etc.
