Able to precisely control and manipulate materials'states at micro/nano-scale level,femtosecond(fs)laser micro/nano processing technology has undergone tremendous development over the past three decades.Free-formi...Able to precisely control and manipulate materials'states at micro/nano-scale level,femtosecond(fs)laser micro/nano processing technology has undergone tremendous development over the past three decades.Free-forming three-dimensional(3D)microscale functional devices and inducing fascinating and unique physical or chemical phenomena have granted this technology powerful versatility that no other technology can match.As this technology advances rapidly in various fields of application,some key challenges have emerged and remain to be urgently addressed.This review firstly introduces the fundamental principles for understanding how fs laser pulses interact with materials and the associated unique phenomena in section 2.Then micro/nano-fabrication in transparent materials by fs laser processing is presented in section 3.Thereafter,several high efficiency/throughput fabrication methods as well as pulse-shaping techniques are listed in sections 4 and 5 reviews four-dimensional(4D)and nanoscale printing realized by fs laser processing technology.Special attention is paid to the heterogeneous integration(HI)of functional materials enabled by fs laser processing in section 6.Several intriguing examples of 3D functional micro-devices created by fs laser-based manufacturing methods such as microfluidics,lab-on-chip,micro-optics,micro-mechanics,micro-electronics,micro-bots and micro-biodevices are reviewed in section 7.Finally,a summary of the review and a perspective are proposed to explore the challenges and future opportunities for further betterment of fs laser micro/nano processing technology.展开更多
Servo scanning 3D micro electrical discharge machining (3D SSMEDM) is a novel and effective method in fabricating complex 3D micro structures with high aspect ratio on conducting materials. In 3D SSMEDM process, the a...Servo scanning 3D micro electrical discharge machining (3D SSMEDM) is a novel and effective method in fabricating complex 3D micro structures with high aspect ratio on conducting materials. In 3D SSMEDM process, the axial wear of tool electrode can be compensated automatically by servo-keeping discharge gap, instead of the traditional methods that depend on experiential models or intermittent compensation. However, the effects of process parameters on 3D SSMEDM have not been reported up until now. In this study, the emphasis is laid on the effects of pulse duration, peak current, machining polarity, track style, track overlap, and scanning velocity on the 3D SSMEDM performances of machining efficiency, processing status, and surface accuracy. A series of experiments were carried out by machining a micro-rectangle cavity (900 μm×600 μm) on doped silicon. The experimental results were obtained as follows. Peak current plays a main role in machining efficiency and surface accuracy. Pulse duration affects obviously the stability of discharge state. The material removal rate of cathode processing is about 3/5 of that of anode processing. Compared with direction-parallel path, contour-parallel path is better in counteracting the lateral wear of tool electrode end. Scanning velocity should be selected moderately to avoid electric arc and short. Track overlap should be slightly less than the radius of tool electrode. In addition, a typical 3D micro structure of eye shape was machined based on the optimized process parameters. These results are beneficial to improve machining stability, accuracy, and efficiency in 3D SSMEDM.展开更多
Micro-gear is an important actuating component used widely in the micro electro mechanical systems(MEMS) devices.The technologies of micro-forming and precision assembly are urgently developed to manufacture the micro...Micro-gear is an important actuating component used widely in the micro electro mechanical systems(MEMS) devices.The technologies of micro-forming and precision assembly are urgently developed to manufacture the micro-double gear with central shaft.In the paper,a novel hy-brid-forming process with two kinds of piercing method have been proposed to manufacture the micro-double gear using micro forming technology.The tests of hybrid forming process were carried out with two steps and the micro-double gear was successfully manufactured with good surface quality.The results also show that the hybrid micro-forming process with central piercing method can improve the defects of inclining shaft generated by double-ended piercing method.The quality evaluation of micro-double gear was conducted with surface roughness,micro-hardness and impact tests.The results show that the micro-double gear with good mechanical properties can meet the requirements of application for milli-machines.展开更多
A seeding strategy was developed in the preparation of cyclotetramethylenetetranitramine(HMX)explosive micro-particles by solvent-antisolvent method, to control their polymorphs from dangerous gamma(y) type to the des...A seeding strategy was developed in the preparation of cyclotetramethylenetetranitramine(HMX)explosive micro-particles by solvent-antisolvent method, to control their polymorphs from dangerous gamma(y) type to the desired and standard beta(β) form with the size distribution of <10.0 μm, by using a low concentration of β-HMX fine particles as micro-seed in the antisolvent medium. All products were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), and dynamic light scattering particle size analyzer. In the next step, the effective factors on the sizes and morphologies of micro-particles in the presence and absence of two soft templates of poly(ethylene glycol)-400(PEG-400) polymer and coconut fatty acid diethanolamide(lauramide) surfactant were investigated. The results of experiments showed that using of water-soluble PEG-400 in the low antisolvent temperatures leads to the production of very spherical particles. Also non-ionic surfactant of lauramide, direct the crystal growth to needle-like structures. The advantages of this method are its capability for the simple production of β-HMX micro-particles in the large scale production process, with the various crystal structures and particles size distributions.展开更多
Colorless and transparent thin films of collodion are prepared on silicon wafers and K9 optical glass substrates by using spin-coating technique.The visible light transmittance,IR absorption spectra and optical consta...Colorless and transparent thin films of collodion are prepared on silicon wafers and K9 optical glass substrates by using spin-coating technique.The visible light transmittance,IR absorption spectra and optical constants of collodion thin film are measured by UV-3501Spectrophotometer,Fourier transform infrared spectrometer(FTIR)and spectroscopic ellipsometry.The measured results show that its average visible light transmittance is 91.9%,and its average infrared absorptivity is better than 0.69/um.In the visible light region,the refractive index of collodion thin film changes in the range of 1.5—1.53,which accords with normal dispersion.The collodion films are etched using oxygen gas plasma.The surface morphology and thickness of etched thin film are measured by the polarizing microscope and MP-100S thickness measurement system,respectively.The results show that the collodion thin film is etched out in the oxygen gas plasma.展开更多
Data collected using the micro rain radar(MRR) situated in Jinan city, eastern China, were used to explore the altitudinal and temporal evolution of rainfall microphysical characteristics, and to analyze the bright ba...Data collected using the micro rain radar(MRR) situated in Jinan city, eastern China, were used to explore the altitudinal and temporal evolution of rainfall microphysical characteristics, and to analyze the bright band(BB) characteristics and hydrometeor classification. Specifically, a low-intensity and stable stratiform precipitation event that occurred from 0000 to0550 UTC 15 February 2015 and featured a BB was studied. During this event, the rainfall intensity was less than 2 mm h-1 at a height of 300 m, which was above the radar site level, so the errors caused by the vertical air motion could be ignored.The freezing height from the radiosonde matched well with the top of the BB observed by the MRR. It was also found that the number of 0.5–1 mm diameter drops showed no noticeable variation below the BB. The maximum fall velocity and the maximum gradient fall velocity(GFV) of the raindrops appeared at the bottom of the BB. Meanwhile, a method that uses the GFV and reflectivity to identify the altitude and the thickness of the BB was established, with which the MRR can provide a reliable and real-time estimation of the 0?C isotherm. The droplet fall velocity was used to classify the types of snow crystals above the BB. In the first 20 min of the selected precipitation event, graupel prevailed above the BB; and at an altitude of2000 m, graupel also dominated in the first 250 min. After 150 min, the existence of graupel and dendritic crystals with water droplets above the BB was inferred.展开更多
It would be well to note that in the absence of clear data about the formation of adaptation systems,or mechanisms of their occurrence,all that is recognized is the realization of the micro evolutionary processes.Ther...It would be well to note that in the absence of clear data about the formation of adaptation systems,or mechanisms of their occurrence,all that is recognized is the realization of the micro evolutionary processes.There is no well-defined connection between information exchange and formation展开更多
A new corn stover roughage processing method, corn stover extrusion and micro-storage processing technology, was introduced from the aspects of basic working principle, production and processing process, characteristi...A new corn stover roughage processing method, corn stover extrusion and micro-storage processing technology, was introduced from the aspects of basic working principle, production and processing process, characteristics of cornstalk via extrusion and micro-storage processing. The technology was proved to be a feasible and practical processing technology of stover feed with broad prospect.展开更多
The characteristics of a kind of comb-drive electrostatic actuated micro-gripper are tested. The test platform using a microscope-CCD-computer, the state information of the micro-gripper obtained by data acquisition a...The characteristics of a kind of comb-drive electrostatic actuated micro-gripper are tested. The test platform using a microscope-CCD-computer, the state information of the micro-gripper obtained by data acquisition and image processing, voltage-displacement characteristic curve is obtained and the mathematical equation is established. The analysis of the characteristic equation has shown the consistency and rationality of the theoretical design and the experimental results. The main factors that cause the difference between the theoretical design and the actual test performance are analyzed, and the design method and experimental results is obtained for the micro-gripper in the field of micro-assembly.展开更多
Micro Food processing industry is gaining its momentum in the recent years in Northeast India and particularly in Manipur.This sector plays an important role in connecting the bridge between the agricultural productio...Micro Food processing industry is gaining its momentum in the recent years in Northeast India and particularly in Manipur.This sector plays an important role in connecting the bridge between the agricultural production and the entrepreneurship development.The region bestows by the abundance of unique and rich agro and horticultural produce gives schemes and projects also add to the development of this sector and to the food entrepreneur by providing financial,technical,infrastructural and business support.The state sharing its border with the Myanmar has a significant impact on the food processing industry particularly in terms of marketing and trading aspects.Food Entrepreneurs should enhance their work on diversifying the horizons of the value added products,increasing job opportunities,marketing,training and technical skills etc.which will ultimately help in developing the Micro food processing sector in the state.展开更多
A low-power complementary metal oxide semiconductor（CMOS） operational amplifier （op-amp） for real-time signal processing of micro air vehicle （MAV） is designed in this paper.Traditional folded cascode architectu...A low-power complementary metal oxide semiconductor（CMOS） operational amplifier （op-amp） for real-time signal processing of micro air vehicle （MAV） is designed in this paper.Traditional folded cascode architecture with positive channel metal oxide semiconductor（PMOS） differential input transistors and sub-threshold technology are applied under the low supply voltage.Simulation results show that this amplifier has significantly low power,while maintaining almost the same gain,bandwidth and other key performances.The power required is only 0.12 mW,which is applicable to low-power and low-voltage real-time signal acquisition and processing system.展开更多
Effects of micro-alloying elements and production process on microstructure, mechanical properties and precipitates of 600 MPa grade rebars were studied by using pilot test, metallographic observa- tion, tensile test,...Effects of micro-alloying elements and production process on microstructure, mechanical properties and precipitates of 600 MPa grade rebars were studied by using pilot test, metallographic observa- tion, tensile test, thermodynamic calculation and transmission electron microscopy. The results show that the tested steels are composed of ferrite and pearlite, in which the conterlt range of pearlite is 33%-45%. For vanadium micro-alloyed steel, interphase preeipitation Strengthening effect of V can be promoted and the yield strength of tested steels can be increased with increasing V content and de- creasing finishing rolling temperature. The temperature of terminated cooling should be more than 700 ℃ when the water cooling is used. When niobium is added to the steel, more coarse （Nb,V）C,N precipitates are generated at high temperature, so that the solid solubility of precipitated phases of vanadium is reduced and the precipitation strengthening effect of vanadium is weakened.展开更多
The hydrodynamic research about the droplet condensing of the multi phase liquid state on the surface of the coal glass and water discusses the deepening process of convex shape curve and the formation of S shape, and...The hydrodynamic research about the droplet condensing of the multi phase liquid state on the surface of the coal glass and water discusses the deepening process of convex shape curve and the formation of S shape, and puts emphasis on describing the diagram formation method of the later. In the induction period the active diagram of the micro droplet is decided by pH value forming as convex shape diagram or S shape diagram. When pH value is above 4.0, the damage of convex shape diagram cannot be recovered, in that case produce S shape activity diagram. When pH value is equal to or above 12.0, the hard surface with alkali liquid state loses adhesion, so that the micro droplet condensing of the multi phase liquid state stops completely. The research result shows that the water cleaning conditions of getting rid of the oil micro droplets can be decided by the pH value.展开更多
This study evaluates the improvement of the radar Quantitative Precipitation Estimation (QPE) by involving microphysical processes in the determination of </span><i><span style="font-family:Verdana...This study evaluates the improvement of the radar Quantitative Precipitation Estimation (QPE) by involving microphysical processes in the determination of </span><i><span style="font-family:Verdana;">Z</span></i><span style="font-family:Verdana;">-</span><i><span style="font-family:Verdana;">R</span></i><span style="font-family:Verdana;"> algorithms. Within the framework of the AMMA campaign, measurements of an X-band radar (Xport), a vertical pointing Micro Rain Radar (MRR) to investigate microphysical processes and a dense network of rain </span><span style="font-family:Verdana;">gauges deployed in Northern Benin (West Africa) in 2006 and 2007 were</span><span style="font-family:Verdana;"> used as support to establish such estimators and evaluate their performance compared to other estimators in the literature. By carefully considering and correcting MRR attenuation and calibration issues, the </span><i><span style="font-family:Verdana;">Z</span></i><span style="font-family:Verdana;">-</span><i><span style="font-family:Verdana;">R</span></i><span style="font-family:Verdana;"> estimator developed </span><span style="font-family:Verdana;">with the contribution of microphysical processes and non-linear least</span></span><span style="font-family:Verdana;">-</span><span style="font-family:""><span style="font-family:Verdana;">squares adjustment proves to be more efficient for quantitative rainfall estimation and produces the best statistic scores than other optimal </span><i><span style="font-family:Verdana;">Z</span></i><span style="font-family:Verdana;">-</span><i><span style="font-family:Verdana;">R</span></i><span style="font-family:Verdana;"> algorithms in the literature. We also find that it gives results comparable to some polarimetric algorithms including microphysical information through DSD integrated parameter retrievals.展开更多
Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples posses...Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples possessed one glass transition temperature （Tg） and two exothermal processes during DSC heating scannings. After being thermally treated above the exothermal peak temperature, they possessed two glass transition temperatures with the disappearance of exothermal peaks, whilst a core/shell structure was formed. This was likely related with the outward diffusion of reactive oligomers to the outer layer of particles.展开更多
We report a readily and cheap method to build taper optical fiber-Er3+ doped microsphere platform to investigate upconversion fluorescence emission and down-conversion laser oscillation with low threshold pump power. ...We report a readily and cheap method to build taper optical fiber-Er3+ doped microsphere platform to investigate upconversion fluorescence emission and down-conversion laser oscillation with low threshold pump power. We demonstrate to dope Er3+ into silica microsphere surface by dipping a single-taper optical fiber into a certain concentration of erbium nitrate solution (Er(NO3)) , then dry it and use the electrical-arc of the optical fiber splicer to melt the tip of taper fiber to form the Er3+-doped silica microsphere due to surface tension induced. We also present a HF acid etching setup to fabricate low loss biconical optical taper fibers. We demonstrate the Er3+ doped silica microsphere triple photons and dual photons absorption process of up-conversion fluorescence emission and down-conversion laser oscillation spectra by using the optical tapered fiber to couple 976 nm/1534 nm pump light source.展开更多
基金supported by National Key R&D Program of China(Grant Nos.2021YFB2802000 and 2022YFB2804300)Science and Technology Commission of Shanghai Municipality(Grant No.21DZ1100500)+3 种基金Shanghai Municipal Science and Technology Major Projectthe Shanghai Frontiers Science Center Program(2021-2025 No.20)National Natural Science Foundation of China(Grant No.61975123)Shanghai Scienceand Technology Innovation Action Plan(Grant No.23JC1403100)。
文摘Able to precisely control and manipulate materials'states at micro/nano-scale level,femtosecond(fs)laser micro/nano processing technology has undergone tremendous development over the past three decades.Free-forming three-dimensional(3D)microscale functional devices and inducing fascinating and unique physical or chemical phenomena have granted this technology powerful versatility that no other technology can match.As this technology advances rapidly in various fields of application,some key challenges have emerged and remain to be urgently addressed.This review firstly introduces the fundamental principles for understanding how fs laser pulses interact with materials and the associated unique phenomena in section 2.Then micro/nano-fabrication in transparent materials by fs laser processing is presented in section 3.Thereafter,several high efficiency/throughput fabrication methods as well as pulse-shaping techniques are listed in sections 4 and 5 reviews four-dimensional(4D)and nanoscale printing realized by fs laser processing technology.Special attention is paid to the heterogeneous integration(HI)of functional materials enabled by fs laser processing in section 6.Several intriguing examples of 3D functional micro-devices created by fs laser-based manufacturing methods such as microfluidics,lab-on-chip,micro-optics,micro-mechanics,micro-electronics,micro-bots and micro-biodevices are reviewed in section 7.Finally,a summary of the review and a perspective are proposed to explore the challenges and future opportunities for further betterment of fs laser micro/nano processing technology.
基金supported by National Natural Science Foundation of China (Grant No. 50905094)National Hi-tech Research and Development Program of China (863 Program, Grant No. 2009AA044204, Grant No. 2009AA044205)China Postdoctoral Science Foundation (Grant No. 20080440378, Grant No. 200902097)
文摘Servo scanning 3D micro electrical discharge machining (3D SSMEDM) is a novel and effective method in fabricating complex 3D micro structures with high aspect ratio on conducting materials. In 3D SSMEDM process, the axial wear of tool electrode can be compensated automatically by servo-keeping discharge gap, instead of the traditional methods that depend on experiential models or intermittent compensation. However, the effects of process parameters on 3D SSMEDM have not been reported up until now. In this study, the emphasis is laid on the effects of pulse duration, peak current, machining polarity, track style, track overlap, and scanning velocity on the 3D SSMEDM performances of machining efficiency, processing status, and surface accuracy. A series of experiments were carried out by machining a micro-rectangle cavity (900 μm×600 μm) on doped silicon. The experimental results were obtained as follows. Peak current plays a main role in machining efficiency and surface accuracy. Pulse duration affects obviously the stability of discharge state. The material removal rate of cathode processing is about 3/5 of that of anode processing. Compared with direction-parallel path, contour-parallel path is better in counteracting the lateral wear of tool electrode end. Scanning velocity should be selected moderately to avoid electric arc and short. Track overlap should be slightly less than the radius of tool electrode. In addition, a typical 3D micro structure of eye shape was machined based on the optimized process parameters. These results are beneficial to improve machining stability, accuracy, and efficiency in 3D SSMEDM.
基金Funded by the Technology Research and Development Program of China (2006AA04Z331)Young Scholars of Heilongjiang Province (JC-05-11 and JC-06-07)
文摘Micro-gear is an important actuating component used widely in the micro electro mechanical systems(MEMS) devices.The technologies of micro-forming and precision assembly are urgently developed to manufacture the micro-double gear with central shaft.In the paper,a novel hy-brid-forming process with two kinds of piercing method have been proposed to manufacture the micro-double gear using micro forming technology.The tests of hybrid forming process were carried out with two steps and the micro-double gear was successfully manufactured with good surface quality.The results also show that the hybrid micro-forming process with central piercing method can improve the defects of inclining shaft generated by double-ended piercing method.The quality evaluation of micro-double gear was conducted with surface roughness,micro-hardness and impact tests.The results show that the micro-double gear with good mechanical properties can meet the requirements of application for milli-machines.
基金financial support of this work by Malek-ashtar University of Technology(I.R.Iran)Grant No.1395064
文摘A seeding strategy was developed in the preparation of cyclotetramethylenetetranitramine(HMX)explosive micro-particles by solvent-antisolvent method, to control their polymorphs from dangerous gamma(y) type to the desired and standard beta(β) form with the size distribution of <10.0 μm, by using a low concentration of β-HMX fine particles as micro-seed in the antisolvent medium. All products were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), and dynamic light scattering particle size analyzer. In the next step, the effective factors on the sizes and morphologies of micro-particles in the presence and absence of two soft templates of poly(ethylene glycol)-400(PEG-400) polymer and coconut fatty acid diethanolamide(lauramide) surfactant were investigated. The results of experiments showed that using of water-soluble PEG-400 in the low antisolvent temperatures leads to the production of very spherical particles. Also non-ionic surfactant of lauramide, direct the crystal growth to needle-like structures. The advantages of this method are its capability for the simple production of β-HMX micro-particles in the large scale production process, with the various crystal structures and particles size distributions.
基金supported by Shaanxi Province Education Department Key Lab Project(2010JS003,1JS041)Chinese PLA General Armament Department Special Photoelectric Project(40405030104)Basic Research Project of National Defense(A0920110019)
文摘Colorless and transparent thin films of collodion are prepared on silicon wafers and K9 optical glass substrates by using spin-coating technique.The visible light transmittance,IR absorption spectra and optical constants of collodion thin film are measured by UV-3501Spectrophotometer,Fourier transform infrared spectrometer(FTIR)and spectroscopic ellipsometry.The measured results show that its average visible light transmittance is 91.9%,and its average infrared absorptivity is better than 0.69/um.In the visible light region,the refractive index of collodion thin film changes in the range of 1.5—1.53,which accords with normal dispersion.The collodion films are etched using oxygen gas plasma.The surface morphology and thickness of etched thin film are measured by the polarizing microscope and MP-100S thickness measurement system,respectively.The results show that the collodion thin film is etched out in the oxygen gas plasma.
基金sponsored by the National Natural Science Foundation of China (Grant Nos. 41475028 and 41530427)
文摘Data collected using the micro rain radar(MRR) situated in Jinan city, eastern China, were used to explore the altitudinal and temporal evolution of rainfall microphysical characteristics, and to analyze the bright band(BB) characteristics and hydrometeor classification. Specifically, a low-intensity and stable stratiform precipitation event that occurred from 0000 to0550 UTC 15 February 2015 and featured a BB was studied. During this event, the rainfall intensity was less than 2 mm h-1 at a height of 300 m, which was above the radar site level, so the errors caused by the vertical air motion could be ignored.The freezing height from the radiosonde matched well with the top of the BB observed by the MRR. It was also found that the number of 0.5–1 mm diameter drops showed no noticeable variation below the BB. The maximum fall velocity and the maximum gradient fall velocity(GFV) of the raindrops appeared at the bottom of the BB. Meanwhile, a method that uses the GFV and reflectivity to identify the altitude and the thickness of the BB was established, with which the MRR can provide a reliable and real-time estimation of the 0?C isotherm. The droplet fall velocity was used to classify the types of snow crystals above the BB. In the first 20 min of the selected precipitation event, graupel prevailed above the BB; and at an altitude of2000 m, graupel also dominated in the first 250 min. After 150 min, the existence of graupel and dendritic crystals with water droplets above the BB was inferred.
文摘It would be well to note that in the absence of clear data about the formation of adaptation systems,or mechanisms of their occurrence,all that is recognized is the realization of the micro evolutionary processes.There is no well-defined connection between information exchange and formation
基金Science and Technology Development Program of Jilin Province(20160204015ny)Construction of Jilin Modern Agricultural Industry Research System(201637)National Beef Cattle Yak Industry Research System(CARS-38)
文摘A new corn stover roughage processing method, corn stover extrusion and micro-storage processing technology, was introduced from the aspects of basic working principle, production and processing process, characteristics of cornstalk via extrusion and micro-storage processing. The technology was proved to be a feasible and practical processing technology of stover feed with broad prospect.
文摘The characteristics of a kind of comb-drive electrostatic actuated micro-gripper are tested. The test platform using a microscope-CCD-computer, the state information of the micro-gripper obtained by data acquisition and image processing, voltage-displacement characteristic curve is obtained and the mathematical equation is established. The analysis of the characteristic equation has shown the consistency and rationality of the theoretical design and the experimental results. The main factors that cause the difference between the theoretical design and the actual test performance are analyzed, and the design method and experimental results is obtained for the micro-gripper in the field of micro-assembly.
文摘Micro Food processing industry is gaining its momentum in the recent years in Northeast India and particularly in Manipur.This sector plays an important role in connecting the bridge between the agricultural production and the entrepreneurship development.The region bestows by the abundance of unique and rich agro and horticultural produce gives schemes and projects also add to the development of this sector and to the food entrepreneur by providing financial,technical,infrastructural and business support.The state sharing its border with the Myanmar has a significant impact on the food processing industry particularly in terms of marketing and trading aspects.Food Entrepreneurs should enhance their work on diversifying the horizons of the value added products,increasing job opportunities,marketing,training and technical skills etc.which will ultimately help in developing the Micro food processing sector in the state.
基金Sponsored by the National Natural Science Foundation of China (60843005)the Basic Research Foundation of Beijing Institute of Technology(20070142018)
文摘A low-power complementary metal oxide semiconductor（CMOS） operational amplifier （op-amp） for real-time signal processing of micro air vehicle （MAV） is designed in this paper.Traditional folded cascode architecture with positive channel metal oxide semiconductor（PMOS） differential input transistors and sub-threshold technology are applied under the low supply voltage.Simulation results show that this amplifier has significantly low power,while maintaining almost the same gain,bandwidth and other key performances.The power required is only 0.12 mW,which is applicable to low-power and low-voltage real-time signal acquisition and processing system.
基金supported by Natural Science Research Project of Anhui Province of China (KJ2016A091)Natural Science Foundation of Anhui Province (1708085ME116)Science and Technology Research Program of Anhui Province of China (1201a0201005)
文摘Effects of micro-alloying elements and production process on microstructure, mechanical properties and precipitates of 600 MPa grade rebars were studied by using pilot test, metallographic observa- tion, tensile test, thermodynamic calculation and transmission electron microscopy. The results show that the tested steels are composed of ferrite and pearlite, in which the conterlt range of pearlite is 33%-45%. For vanadium micro-alloyed steel, interphase preeipitation Strengthening effect of V can be promoted and the yield strength of tested steels can be increased with increasing V content and de- creasing finishing rolling temperature. The temperature of terminated cooling should be more than 700 ℃ when the water cooling is used. When niobium is added to the steel, more coarse （Nb,V）C,N precipitates are generated at high temperature, so that the solid solubility of precipitated phases of vanadium is reduced and the precipitation strengthening effect of vanadium is weakened.
文摘The hydrodynamic research about the droplet condensing of the multi phase liquid state on the surface of the coal glass and water discusses the deepening process of convex shape curve and the formation of S shape, and puts emphasis on describing the diagram formation method of the later. In the induction period the active diagram of the micro droplet is decided by pH value forming as convex shape diagram or S shape diagram. When pH value is above 4.0, the damage of convex shape diagram cannot be recovered, in that case produce S shape activity diagram. When pH value is equal to or above 12.0, the hard surface with alkali liquid state loses adhesion, so that the micro droplet condensing of the multi phase liquid state stops completely. The research result shows that the water cleaning conditions of getting rid of the oil micro droplets can be decided by the pH value.
文摘This study evaluates the improvement of the radar Quantitative Precipitation Estimation (QPE) by involving microphysical processes in the determination of </span><i><span style="font-family:Verdana;">Z</span></i><span style="font-family:Verdana;">-</span><i><span style="font-family:Verdana;">R</span></i><span style="font-family:Verdana;"> algorithms. Within the framework of the AMMA campaign, measurements of an X-band radar (Xport), a vertical pointing Micro Rain Radar (MRR) to investigate microphysical processes and a dense network of rain </span><span style="font-family:Verdana;">gauges deployed in Northern Benin (West Africa) in 2006 and 2007 were</span><span style="font-family:Verdana;"> used as support to establish such estimators and evaluate their performance compared to other estimators in the literature. By carefully considering and correcting MRR attenuation and calibration issues, the </span><i><span style="font-family:Verdana;">Z</span></i><span style="font-family:Verdana;">-</span><i><span style="font-family:Verdana;">R</span></i><span style="font-family:Verdana;"> estimator developed </span><span style="font-family:Verdana;">with the contribution of microphysical processes and non-linear least</span></span><span style="font-family:Verdana;">-</span><span style="font-family:""><span style="font-family:Verdana;">squares adjustment proves to be more efficient for quantitative rainfall estimation and produces the best statistic scores than other optimal </span><i><span style="font-family:Verdana;">Z</span></i><span style="font-family:Verdana;">-</span><i><span style="font-family:Verdana;">R</span></i><span style="font-family:Verdana;"> algorithms in the literature. We also find that it gives results comparable to some polarimetric algorithms including microphysical information through DSD integrated parameter retrievals.
基金This work was financially supported by the National Natural Science Foundation of China(No.20104008).
文摘Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples possessed one glass transition temperature （Tg） and two exothermal processes during DSC heating scannings. After being thermally treated above the exothermal peak temperature, they possessed two glass transition temperatures with the disappearance of exothermal peaks, whilst a core/shell structure was formed. This was likely related with the outward diffusion of reactive oligomers to the outer layer of particles.
文摘We report a readily and cheap method to build taper optical fiber-Er3+ doped microsphere platform to investigate upconversion fluorescence emission and down-conversion laser oscillation with low threshold pump power. We demonstrate to dope Er3+ into silica microsphere surface by dipping a single-taper optical fiber into a certain concentration of erbium nitrate solution (Er(NO3)) , then dry it and use the electrical-arc of the optical fiber splicer to melt the tip of taper fiber to form the Er3+-doped silica microsphere due to surface tension induced. We also present a HF acid etching setup to fabricate low loss biconical optical taper fibers. We demonstrate the Er3+ doped silica microsphere triple photons and dual photons absorption process of up-conversion fluorescence emission and down-conversion laser oscillation spectra by using the optical tapered fiber to couple 976 nm/1534 nm pump light source.
