Solid-state wave gyroscope is one kind of high-performance vibrating gyroscopes. The present work develops a new type of solid-state wave gyroscope—a ring vibrating gyroscope driven by piezo-electrodes located on the...Solid-state wave gyroscope is one kind of high-performance vibrating gyroscopes. The present work develops a new type of solid-state wave gyroscope—a ring vibrating gyroscope driven by piezo-electrodes located on the sidewall of the structure. It has advantages of large vibrating amplitude, high energy conversion efficiency and compact structure. The working principle of the piezoelectric ring vibrating gyroscope is based on the inertia effect of the standing wave in the axisymmetric resonator caused by Coriolis force. The finite element method(FEM) analysis has been implemented to characterize the ring type resonator. The prototypal gyroscope was manufactured and has been trimmed by mechanical way. The harmonic response of the ring vibrating gyroscope has been tested. The resonating frequency of the ring type resonator is 3715.6 Hz and the frequency split of the two working modes before trimming was about 5 Hz and was reduced to sub-0.01 Hz after trimming procedure. The Q-factor of the ring type resonator was 2504. Then, the turntable experiment was implemented. The measured scale factor k is 9.24 m V/[(°)·s] and the full scale range of the gyroscope is larger than ±300(°)/s.展开更多
The emerging two-dimensional MXene-derived quantum dots(MQDs)have garnered considerable research interest owing to their abundant active edge atoms,excellent electrical conductivity,and remarkable optical properties.C...The emerging two-dimensional MXene-derived quantum dots(MQDs)have garnered considerable research interest owing to their abundant active edge atoms,excellent electrical conductivity,and remarkable optical properties.Compared with their two-dimensional(2D)counterpart MXene,MQDs with forceful size and quantum confinement effects exhibit more unparalleled properties and have considerably contributed to the advanced photocatalysis,detection,energy storage,and biomedicine fields.This critical review summarizes the fundamental properties of MQDs in terms of structure,electricity,and optics.The mechanism,characteristics,and comparisons of two typical synthesis strategies(traditional chemical method and novel fluorine-free or chemical-free method)are also presented.Furthermore,the similarities and differences between MQDs and 2D MXenes are introduced in terms of their functional groups,light absorption capacity,energy band structure,and other properties.Moreover,recent advances in the applications of MQD-based materials for energy conversion and storage(ECS)are discussed,including photocatalysis,batteries,and supercapacitors.Finally,current challenges and future opportunities for advancing MQD-based materials in the promising ECS field are presented.展开更多
The dynamic load spectrum is one of the most important basis of design and dynamic characteristics analysis of machines. But it is difficult to measure it on many occasions, especially for mining machines, due to thei...The dynamic load spectrum is one of the most important basis of design and dynamic characteristics analysis of machines. But it is difficult to measure it on many occasions, especially for mining machines, due to their bad working circumstances and high cost of measurements. For such situation, the load spectrum has to be obtained by indirect determination methods. A new method to identify the load spectrum, cepstrum analysis method, was presented in this paper. This method can be used to eliminate the filtering influence of transfer function to the response signals so that the load spectrum can be determined indirectly. The experimental and engineering actual examples indicates that this method has the advantages that the calculation is simple and the measurement is easy.展开更多
ZnO hierarchical aggregates have been successfully synthesized by solvothermal methods through reaction of zinc acetate and potassium hydroxide in methanol solution. The shapes of the aggregates were controlled by var...ZnO hierarchical aggregates have been successfully synthesized by solvothermal methods through reaction of zinc acetate and potassium hydroxide in methanol solution. The shapes of the aggregates were controlled by varying the ratio of Zn2~ and OH- ions in the reaction system, while the size can be tuned from 2μm to 100 nm. Oriented attachment was found to be the main mechanism of the three-dimensional assembly of small ZnO nanocrystallites into large aggregates. The performance of these aggregates in dye-sensitized solar cells （DSCs） indicated that hierarchical structured photoelectrodes can increase energy conversion efficiency of DSCs effectively when the sizes of aggregates match the wavelengths of visible light.展开更多
Semiconductor nanowires （NW） possess several beneficial properties for efficient conversion of solar energy into electricity and chemical energy. Due to their efficient absorption of light, short distances for minor...Semiconductor nanowires （NW） possess several beneficial properties for efficient conversion of solar energy into electricity and chemical energy. Due to their efficient absorption of light, short distances for minority carriers to travel, high surface-to-volume ratios, and the availability of scalable synthesis methods, they provide a pathway to address the low cost-to-power requirements for widescale adaptation of solar energy conversion technologies. Here we highlight recent progress in our group towards implementation of NW components as photovoltaic and photoelectrochemical energy conversion devices. An emphasis is placed on the unique properties of these one-dimensional （1D） structures, which enable the use of abundant, low-cost materials and improved energy conversion efficiency compared to bulk devices.展开更多
基金Projects(51335011,51275522)supported by the National Natural Science Foundation of ChinaProject(HPCM-2013-08)supported by Key Lab Open Foundation of State Key Laboratory of High Performance(Complex Manufacturing),Central South University,China
文摘Solid-state wave gyroscope is one kind of high-performance vibrating gyroscopes. The present work develops a new type of solid-state wave gyroscope—a ring vibrating gyroscope driven by piezo-electrodes located on the sidewall of the structure. It has advantages of large vibrating amplitude, high energy conversion efficiency and compact structure. The working principle of the piezoelectric ring vibrating gyroscope is based on the inertia effect of the standing wave in the axisymmetric resonator caused by Coriolis force. The finite element method(FEM) analysis has been implemented to characterize the ring type resonator. The prototypal gyroscope was manufactured and has been trimmed by mechanical way. The harmonic response of the ring vibrating gyroscope has been tested. The resonating frequency of the ring type resonator is 3715.6 Hz and the frequency split of the two working modes before trimming was about 5 Hz and was reduced to sub-0.01 Hz after trimming procedure. The Q-factor of the ring type resonator was 2504. Then, the turntable experiment was implemented. The measured scale factor k is 9.24 m V/[(°)·s] and the full scale range of the gyroscope is larger than ±300(°)/s.
文摘The emerging two-dimensional MXene-derived quantum dots(MQDs)have garnered considerable research interest owing to their abundant active edge atoms,excellent electrical conductivity,and remarkable optical properties.Compared with their two-dimensional(2D)counterpart MXene,MQDs with forceful size and quantum confinement effects exhibit more unparalleled properties and have considerably contributed to the advanced photocatalysis,detection,energy storage,and biomedicine fields.This critical review summarizes the fundamental properties of MQDs in terms of structure,electricity,and optics.The mechanism,characteristics,and comparisons of two typical synthesis strategies(traditional chemical method and novel fluorine-free or chemical-free method)are also presented.Furthermore,the similarities and differences between MQDs and 2D MXenes are introduced in terms of their functional groups,light absorption capacity,energy band structure,and other properties.Moreover,recent advances in the applications of MQD-based materials for energy conversion and storage(ECS)are discussed,including photocatalysis,batteries,and supercapacitors.Finally,current challenges and future opportunities for advancing MQD-based materials in the promising ECS field are presented.
文摘The dynamic load spectrum is one of the most important basis of design and dynamic characteristics analysis of machines. But it is difficult to measure it on many occasions, especially for mining machines, due to their bad working circumstances and high cost of measurements. For such situation, the load spectrum has to be obtained by indirect determination methods. A new method to identify the load spectrum, cepstrum analysis method, was presented in this paper. This method can be used to eliminate the filtering influence of transfer function to the response signals so that the load spectrum can be determined indirectly. The experimental and engineering actual examples indicates that this method has the advantages that the calculation is simple and the measurement is easy.
文摘ZnO hierarchical aggregates have been successfully synthesized by solvothermal methods through reaction of zinc acetate and potassium hydroxide in methanol solution. The shapes of the aggregates were controlled by varying the ratio of Zn2~ and OH- ions in the reaction system, while the size can be tuned from 2μm to 100 nm. Oriented attachment was found to be the main mechanism of the three-dimensional assembly of small ZnO nanocrystallites into large aggregates. The performance of these aggregates in dye-sensitized solar cells （DSCs） indicated that hierarchical structured photoelectrodes can increase energy conversion efficiency of DSCs effectively when the sizes of aggregates match the wavelengths of visible light.
文摘Semiconductor nanowires （NW） possess several beneficial properties for efficient conversion of solar energy into electricity and chemical energy. Due to their efficient absorption of light, short distances for minority carriers to travel, high surface-to-volume ratios, and the availability of scalable synthesis methods, they provide a pathway to address the low cost-to-power requirements for widescale adaptation of solar energy conversion technologies. Here we highlight recent progress in our group towards implementation of NW components as photovoltaic and photoelectrochemical energy conversion devices. An emphasis is placed on the unique properties of these one-dimensional （1D） structures, which enable the use of abundant, low-cost materials and improved energy conversion efficiency compared to bulk devices.
