To understand the discharge characteristics under a gap of micrometers,the breakdown voltage and current–voltage curve are measured experimentally in a needle-to-plate electrode at a microscale gap of 3–50 μm in ai...To understand the discharge characteristics under a gap of micrometers,the breakdown voltage and current–voltage curve are measured experimentally in a needle-to-plate electrode at a microscale gap of 3–50 μm in air.The effect of the needle radius and the gas pressure on the discharge characteristics are tested.The results show that when the gap is larger than 10 μm,the relation between the breakdown voltage and the gap looks like the Paschen curve;while below 10 μm,the breakdown voltage is nearly constant in the range of the tested gap.However,at the same gap distance,the breakdown voltage is still affected by the pressure and shows a trend similar to Paschen＇s law.The current–voltage characteristic in all the gaps is similar and follows the trend of a typical Townsend-to-glow discharge.A simple model is used to explain the non-normality of breakdown in the micro-gaps.The Townsend mechanism is suggested to control the breakdown process in this configuration before the gap reduces much smaller in air.展开更多
We describe the microfabrication of ^85Rb vapour cells using a glass-silicon anodic bonding technique and in situ chemical reaction between rubidium chloride and barium azide to produce Rb. Under controlled conditions...We describe the microfabrication of ^85Rb vapour cells using a glass-silicon anodic bonding technique and in situ chemical reaction between rubidium chloride and barium azide to produce Rb. Under controlled conditions, the pure metallic Rb drops and buffer gases were obtained in the cells with a few mm^3 internal volumes during the cell sealing process. At an ambient temperature of 90 ℃ the optical absorption resonance of ^85Rb D1 transition with proper broadening and the corresponding coherent population trapping （CPT） resonance, with a signal contrast of 1.5% and linewidth of about 1.7 kHz, have been detected. The sealing quality and the stability of the cells have also been demonstrated experimentally by using the helium leaking detection and the after-9-month optoelectronics measurement which shows a similar CPT signal as its original status. In addition, the physics package of chip-scale atomic clock （CSAC） based on the cell was realized. The measured frequency stability of the physics package can reach to 2.1 × 10^-10 at one second when the cell was heated to 100 ℃ which proved that the cell has the quality to be used in portable and battery-operated devices.展开更多
The response characteristics of resistance is observed by the analysis of experimental data of micro scale semiconductor bridge （MSCB） under different voltage inputs. Two critical voltages are found. One is called e...The response characteristics of resistance is observed by the analysis of experimental data of micro scale semiconductor bridge （MSCB） under different voltage inputs. Two critical voltages are found. One is called exploding voltage, above which the MSCB can be melted and vaporized without generating a plasma, and the other is called producing a plasma voltage, above which the MSCB is entirely vaporized, and then the current flows through the vapor producing the plasma. Based on the non Fourier heat conduction theory, the electrothermal energy conversion model is es tablished for the stage from heating to exploding, and then the correlation of MSCB and time is ob tained by graphic calculation. Importantly, the critical exploding voltage and exploding time are also derivate. With the comparison between the analytical result from the theoretical model and that from experimental data, it has been demonstrated that the theoretical model is reasonable and feasible for designing the exploding voltage and exploding time.展开更多
A new 6-DOF micro-manipulation robot based on 3-PPTTRS parallel mechanisms in combination with flexure hinges is proposed. The design principle of the mechanism is introduced, and the kinematics analysis method based ...A new 6-DOF micro-manipulation robot based on 3-PPTTRS parallel mechanisms in combination with flexure hinges is proposed. The design principle of the mechanism is introduced, and the kinematics analysis method based on differentiation is used to get the (inverse) kinematics equations. Then a micro-scale motion precision simulation method is proposed according to finite element analysis (FEA), and the prediction of robot’s motion precision in design phase is realized. The simulation result indicates that the 6-DOF micro-manipulation robot can meet the design specification.展开更多
Wave-number spectral characteristics of drift wave micro-turbulence with large-scale structures （LSSs） including zonal flows （ZFs） and Kelvin-Holmheltz （KH） mode are investigated based on three dimensional gyrof...Wave-number spectral characteristics of drift wave micro-turbulence with large-scale structures （LSSs） including zonal flows （ZFs） and Kelvin-Holmheltz （KH） mode are investigated based on three dimensional gyrofluid simulations in a slab geometry. The focus is on the property of the wave-number spectral scaling law of the ambient turbulence under the back reaction of the self-generated LSSs. A comparison of the spectral scaling laws between ion/electron temperature gradient （ITG/ETG） driven turbulences is presented. It is shown that the spectral scaling of the ITG turbulence with robust ZFs is fitted well by an exponential-law function （Φ^2/2）E∝e^-λkx in kx and a power-law one in （Φ^2/2）p∝ky^-β in ky. However, the ETG turbulence is characterized by a mixing Kolmogorov-like power-law and exponential-law （Φ^2/2）E∝e-λkx＇yk^-3x,y/（1 ＋ k^2x,y）^2 scaling for both kx and ky spectra due to the ZFs and KH mode dynamics, with λ and β the slope index factors. The underlying physical mechanism is understood as the spectral scattering caused by the back-reaction of the LSSs on the ambient turbulence. These findings may provide helpful guideline to diagnose the plasma fluctuations and flow structures in experiments.展开更多
Untethered micro/nanorobots that can wirelessly control their motion and deformation state have gained enormous interest in remote sensing applications due to their unique motion characteristics in various media and d...Untethered micro/nanorobots that can wirelessly control their motion and deformation state have gained enormous interest in remote sensing applications due to their unique motion characteristics in various media and diverse functionalities.Researchers are developing micro/nanorobots as innovative tools to improve sensing performance and miniaturize sensing systems,enabling in situ detection of substances that traditional sensing methods struggle to achieve.Over the past decade of development,significant research progress has been made in designing sensing strategies based on micro/nanorobots,employing various coordinated control and sensing approaches.This review summarizes the latest developments on micro/nanorobots for remote sensing applications by utilizing the self-generated signals of the robots,robot behavior,microrobotic manipulation,and robot-environment interactions.Providing recent studies and relevant applications in remote sensing,we also discuss the challenges and future perspectives facing micro/nanorobots-based intelligent sensing platforms to achieve sensing in complex environments,translating lab research achievements into widespread real applications.展开更多
The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano...The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro-and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept,the micro-and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by selforganization of the micro-and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro-and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.展开更多
Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental mic...Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental microanalysis via LIBS. Microanalysis and multimode sampling methodologies were designed in this study. The relative standard deviation （RSD） approach was performed to optimize the multi-shot measurements. Taking advantage of the capability with no or minimal sample pre-treatment of LIBS, a thermodynamic chart of four elements （Mg, Ca, Ba, and Na） was created from twelve collection regions. The diagram of elemental distribution on a micro-scale was generated to explore the nature of Juncus effusus L. by LIBS. The results demon- strated that LIBS is a promising technique for rapid elemental microanalysis of heterogeneous samples.展开更多
Based on the qualitative study of microscopic reservoir features using core analysis,cast and fluorescence thin sections inspection,scanning electron microscope(SEM)and field emission scanning electron microscope(FESE...Based on the qualitative study of microscopic reservoir features using core analysis,cast and fluorescence thin sections inspection,scanning electron microscope(SEM)and field emission scanning electron microscope(FESEM)and quantitative examination of pore size and geometry using mercury injection,nano-CT and nitrogen adsorption,reservoir rock of Da’anzhai Member were divided into 9 types,while storage spaces were divided into 4 types and 14 sub-types.The study shows that sparry coquina is the most promising reservoir type.Pores that smaller than 1μm in diameter contribute 91.27%of storage space volume.Most of them exhibit slot-like geometry with good connectivity.By building up storage space models,it was revealed that micron scale storage spaces mainly composed of fractures and nanometer scale pores and fractures form multi-scale dual porosity system.Low resource abundance,small single well controlled reserve,and low production are related to the nano-scale pore space in Da’anzhai Memer,whereas the dual-porosity system composed of pores and fractures makes for long-term oil yield.Due to the existence of abundant slot-like pore space and fractures,economic tight oil production was achieved without stimulations.展开更多
基金supported by National Natural Science Foundation of China(11475019)the Electrostatic Research Foundation of Liu Shanghe Academicians and Experts Workstation,Beijing Orient Institute of Measurement and Test(BOIMTLSHJD20161002)
文摘To understand the discharge characteristics under a gap of micrometers,the breakdown voltage and current–voltage curve are measured experimentally in a needle-to-plate electrode at a microscale gap of 3–50 μm in air.The effect of the needle radius and the gas pressure on the discharge characteristics are tested.The results show that when the gap is larger than 10 μm,the relation between the breakdown voltage and the gap looks like the Paschen curve;while below 10 μm,the breakdown voltage is nearly constant in the range of the tested gap.However,at the same gap distance,the breakdown voltage is still affected by the pressure and shows a trend similar to Paschen＇s law.The current–voltage characteristic in all the gaps is similar and follows the trend of a typical Townsend-to-glow discharge.A simple model is used to explain the non-normality of breakdown in the micro-gaps.The Townsend mechanism is suggested to control the breakdown process in this configuration before the gap reduces much smaller in air.
基金Project supported by National 863/973 Plans Projects (Grant Nos. 2006AA04Z361,2006CB932402)NSFC (Grant No. 60971002)
文摘We describe the microfabrication of ^85Rb vapour cells using a glass-silicon anodic bonding technique and in situ chemical reaction between rubidium chloride and barium azide to produce Rb. Under controlled conditions, the pure metallic Rb drops and buffer gases were obtained in the cells with a few mm^3 internal volumes during the cell sealing process. At an ambient temperature of 90 ℃ the optical absorption resonance of ^85Rb D1 transition with proper broadening and the corresponding coherent population trapping （CPT） resonance, with a signal contrast of 1.5% and linewidth of about 1.7 kHz, have been detected. The sealing quality and the stability of the cells have also been demonstrated experimentally by using the helium leaking detection and the after-9-month optoelectronics measurement which shows a similar CPT signal as its original status. In addition, the physics package of chip-scale atomic clock （CSAC） based on the cell was realized. The measured frequency stability of the physics package can reach to 2.1 × 10^-10 at one second when the cell was heated to 100 ℃ which proved that the cell has the quality to be used in portable and battery-operated devices.
基金Supported by the National Basic Research Program of China("973"Program)(51299)
文摘The response characteristics of resistance is observed by the analysis of experimental data of micro scale semiconductor bridge （MSCB） under different voltage inputs. Two critical voltages are found. One is called exploding voltage, above which the MSCB can be melted and vaporized without generating a plasma, and the other is called producing a plasma voltage, above which the MSCB is entirely vaporized, and then the current flows through the vapor producing the plasma. Based on the non Fourier heat conduction theory, the electrothermal energy conversion model is es tablished for the stage from heating to exploding, and then the correlation of MSCB and time is ob tained by graphic calculation. Importantly, the critical exploding voltage and exploding time are also derivate. With the comparison between the analytical result from the theoretical model and that from experimental data, it has been demonstrated that the theoretical model is reasonable and feasible for designing the exploding voltage and exploding time.
基金the Research Fund for the Doctoral Programof Higher Education(20060007023)
文摘A new 6-DOF micro-manipulation robot based on 3-PPTTRS parallel mechanisms in combination with flexure hinges is proposed. The design principle of the mechanism is introduced, and the kinematics analysis method based on differentiation is used to get the (inverse) kinematics equations. Then a micro-scale motion precision simulation method is proposed according to finite element analysis (FEA), and the prediction of robot’s motion precision in design phase is realized. The simulation result indicates that the 6-DOF micro-manipulation robot can meet the design specification.
文摘Wave-number spectral characteristics of drift wave micro-turbulence with large-scale structures （LSSs） including zonal flows （ZFs） and Kelvin-Holmheltz （KH） mode are investigated based on three dimensional gyrofluid simulations in a slab geometry. The focus is on the property of the wave-number spectral scaling law of the ambient turbulence under the back reaction of the self-generated LSSs. A comparison of the spectral scaling laws between ion/electron temperature gradient （ITG/ETG） driven turbulences is presented. It is shown that the spectral scaling of the ITG turbulence with robust ZFs is fitted well by an exponential-law function （Φ^2/2）E∝e^-λkx in kx and a power-law one in （Φ^2/2）p∝ky^-β in ky. However, the ETG turbulence is characterized by a mixing Kolmogorov-like power-law and exponential-law （Φ^2/2）E∝e-λkx＇yk^-3x,y/（1 ＋ k^2x,y）^2 scaling for both kx and ky spectra due to the ZFs and KH mode dynamics, with λ and β the slope index factors. The underlying physical mechanism is understood as the spectral scattering caused by the back-reaction of the LSSs on the ambient turbulence. These findings may provide helpful guideline to diagnose the plasma fluctuations and flow structures in experiments.
基金supported by the National Natural Science Foundation under Project No. 52205590the Natural Science Foundation of Jiangsu Province under Project No. BK20220834+4 种基金the Start-up Research Fund of Southeast University under Project No. RF1028623098the Xiaomi Foundation/ Xiaomi Young Talents Programsupported by the Research Impact Fund (project no. R4015-21)Research Fellow Scheme (project no. RFS2122-4S03)the EU-Hong Kong Research and Innovation Cooperation Co-funding Mechanism (project no. E-CUHK401/20) from the Research Grants Council (RGC) of Hong Kong, the SIAT-CUHK Joint Laboratory of Robotics and Intelligent Systems, and the Multi-Scale Medical Robotics Center (MRC), InnoHK, at the Hong Kong Science Park
文摘Untethered micro/nanorobots that can wirelessly control their motion and deformation state have gained enormous interest in remote sensing applications due to their unique motion characteristics in various media and diverse functionalities.Researchers are developing micro/nanorobots as innovative tools to improve sensing performance and miniaturize sensing systems,enabling in situ detection of substances that traditional sensing methods struggle to achieve.Over the past decade of development,significant research progress has been made in designing sensing strategies based on micro/nanorobots,employing various coordinated control and sensing approaches.This review summarizes the latest developments on micro/nanorobots for remote sensing applications by utilizing the self-generated signals of the robots,robot behavior,microrobotic manipulation,and robot-environment interactions.Providing recent studies and relevant applications in remote sensing,we also discuss the challenges and future perspectives facing micro/nanorobots-based intelligent sensing platforms to achieve sensing in complex environments,translating lab research achievements into widespread real applications.
基金supported by the Western-Caucasus Research Center
文摘The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro-and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept,the micro-and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by selforganization of the micro-and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro-and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.
基金supported by National Natural Science Foundation of China(No.81303218)Beijing Municipal Government for the University Affiliated with the Party Central CommitteeDoctoral Fund of Ministry of Education of China(No.20130013120006)
文摘Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental microanalysis via LIBS. Microanalysis and multimode sampling methodologies were designed in this study. The relative standard deviation （RSD） approach was performed to optimize the multi-shot measurements. Taking advantage of the capability with no or minimal sample pre-treatment of LIBS, a thermodynamic chart of four elements （Mg, Ca, Ba, and Na） was created from twelve collection regions. The diagram of elemental distribution on a micro-scale was generated to explore the nature of Juncus effusus L. by LIBS. The results demon- strated that LIBS is a promising technique for rapid elemental microanalysis of heterogeneous samples.
基金Supported by the China National Science and Technology Major Project(2016ZX05046-001)
文摘Based on the qualitative study of microscopic reservoir features using core analysis,cast and fluorescence thin sections inspection,scanning electron microscope(SEM)and field emission scanning electron microscope(FESEM)and quantitative examination of pore size and geometry using mercury injection,nano-CT and nitrogen adsorption,reservoir rock of Da’anzhai Member were divided into 9 types,while storage spaces were divided into 4 types and 14 sub-types.The study shows that sparry coquina is the most promising reservoir type.Pores that smaller than 1μm in diameter contribute 91.27%of storage space volume.Most of them exhibit slot-like geometry with good connectivity.By building up storage space models,it was revealed that micron scale storage spaces mainly composed of fractures and nanometer scale pores and fractures form multi-scale dual porosity system.Low resource abundance,small single well controlled reserve,and low production are related to the nano-scale pore space in Da’anzhai Memer,whereas the dual-porosity system composed of pores and fractures makes for long-term oil yield.Due to the existence of abundant slot-like pore space and fractures,economic tight oil production was achieved without stimulations.
