TP242.62 2001053743一种提高双目视觉测量精度的逐步逼近方法=A prograssive approach method for improving the accuracy of binocular vision measurement[刊,中]/双凯,董守平(石油大学机电学院.北京(102200))//光电工程.—2000,27(3).
To investigate the overall performance of reverse energy bypass scramjet,firstly a variable spe⁃cific heat method combined with a chemical balance calculation module for combustion products were used to es⁃tablish a b...To investigate the overall performance of reverse energy bypass scramjet,firstly a variable spe⁃cific heat method combined with a chemical balance calculation module for combustion products were used to es⁃tablish a benchmark scramjet performance evaluation model.Based on the test data of typical flying point of Mach 7 with the altitude of 29 km,the reliability of the model was verified.The deviations of parameters such as the to⁃tal pressure loss of combustor between the model and the test data were analyzed.Furtherly,an analytical method for post-combustion magnetohydrodynamic power generation was established;by embedding the above method into the overall performance evaluation model,performance prediction considering the power generation effect was realized.Finally,based on the above model,variety regulations of the inlet and the outlet parameters of the power generation channel and performance parameters including the engine specific impulse and the unit thrust under different enthalpy extraction ratios and load factors were analyzed.It could be concluded that the model can reliably predict the variations of key parameters.As the value of the load factor increases,the value of the conduc⁃tivity required to reach the specified enthalpy extraction ratio first decreases and then increases,which is approxi⁃mately parabolic.In order to reduce the demand for the gas conductivity for MHD power generation,the load fac⁃tor should be around 0.5.When the load factor is 0.4 and the magnetic induction intensity is 2.5 T,if the enthalpy extraction ratio reaches 0.5%,the engine specific impulse performance reduces about 3.58%.展开更多
We report an economical approach for the fabrication of laser-produced graphene(LPG)electrodes,which results in an improved electrochemical performance.Polyimide polymer was used as the starting material for LPG synth...We report an economical approach for the fabrication of laser-produced graphene(LPG)electrodes,which results in an improved electrochemical performance.Polyimide polymer was used as the starting material for LPG synthesis and was irradiated under ambient conditions with a CO_(2) laser.The prepared LPG samples were characterized by Raman spectroscopy and FTIR,which validated the formation of multilayer graphene containing sp2 hybridized C=C bonds.FE-SEM revealed three-dimensional(3D)sheet-like structures,while HR-TEM images showed lattice planes with an interplanar spacing of approximately 0.33 nm,corres-ponding to the(002)plane of graphene.Their electrochemical performance showed a remarkable areal specific capacitance(CA)of 51 mF cm^(−2)(170 F g^(-1))at 1 mA cm^(−2)(3.3 A g^(-1))in a three-electrode configuration with 1 mol L^(−1) KOH as the aqueous electrolyte.The LPG electrodes produced an energy density of~3.5μWh cm^(−2) and a power density of~350μW cm^(−2),demonstrating signific-ant energy storage ability.They also had an excellent cycling stability,retaining 87%of their specific capacitance after 3000 cycles at 1 mA/cm^(2).A symmetric supercapacitor fabricated with LPG electrodes and the 1 mol L^(−1) KOH electrolyte had a specific capacit-ance of 23 mF cm^(−2) and showed excellent retention after 10000 cycles,showing LPG’s potential for use in supercapacitors.展开更多
The reverse magnetohydrodynamic(MHD)energy bypass technology is a promising energy redis⁃tribution technology in the scramjet system,in augmented with a power generation equipment to supply the neces⁃sary long-distanc...The reverse magnetohydrodynamic(MHD)energy bypass technology is a promising energy redis⁃tribution technology in the scramjet system,in augmented with a power generation equipment to supply the neces⁃sary long-distance flight airframe power.In this paper,a computational model of the scramjet magnetohydrody⁃namic channel is developed and verified by using the commercial software Fluent.It is found that when the mag⁃netic induction intensity is 1,2,3,4 T,the power generation efficiency is 22.5%,22.3%,22.0%,21.5%,and decreases with the increase of the magnetic induction intensity,and the enthalpy extraction rate is 0.026%,0.1%,0.21%,0.34%,and increases with the increase of the magnetic induction intensity.The deceleration ef⁃fect of electromagnetic action on the airflow in the power channel increases with the increase of magnetic induc⁃tion intensity.The stronger the magnetic field intensity,the more obvious the decreasing effect of fluid Mach num⁃ber in the channel.The power generation efficiency decreases as the magnetic induction intensity increases and the enthalpy extraction rate is reversed.As the local currents gathering at inlet and outlet of the power generation area,total temperature and enthalpy along the flow direction do not vary linearly,and there are maximum and minimum values at inlet and outlet.Increasing the number of electrodes can effectively regulate the percentage of Joule heat dissipation,which can improve the power generation efficiency.展开更多
All-solid-state lithium-ion batteries(LIBs)using ceramic electrolytes are considered the ideal form of rechargeable batteries due to their high energy density and safety.However,in the pursuit of all-solid-state LIBs,...All-solid-state lithium-ion batteries(LIBs)using ceramic electrolytes are considered the ideal form of rechargeable batteries due to their high energy density and safety.However,in the pursuit of all-solid-state LIBs,the issue of lithium resource availability is selectively overlooked.Considering that the amount of lithium required for all-solidstate LIBs is not sustainable with current lithium resources,another system that also offers the dual advantages of high energy density and safetydall-solid-state sodium-ion batteries(SIBs)dholds significant sustainable advantages and is likely to be the strong contender in the competition for developing next-generation high-energy-density batteries.This article briefly introduces the research status of all-solid-state SIBs,explains the sources of their advantages,and discusses potential approaches to the development of solid sodium-ion conductors,aiming to spark the interest of researchers and attract more attention to the field of all-solid-state SIBs.展开更多
With increasing demand on energy density of lithium-ion battery,wide electrochemical window and safety performance are the crucial request for next generation electrolyte.Gel-electrolyte as a pioneer for electrolyte s...With increasing demand on energy density of lithium-ion battery,wide electrochemical window and safety performance are the crucial request for next generation electrolyte.Gel-electrolyte as a pioneer for electrolyte solidization development aims to solve the safety and electrochemical window problems.However,low ionic conductivity and poor physical performance prohibit its further application.Herein,a fast-ionic conductor(Li_(2.64)(Sc_(0.9)Ti_(0.1))_(2)(PO_(4))_(3))(LSTP)was added into poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)base gel-electrolyte to enhance mechanical properties and ionic conductivity.Evidences reveal that LSTP was able to weaken interforce between polymer chains,which increased the ionic conductibility and decreased interface resistance during the cycling significantly.The obtained LiFePO_(4)/hybrid gel-electrolyte/Li-metal coin cell exhibited excellent rate capacity(145 mA·h/g at 1C,95 mA·h/g at 3C,28℃)which presented a potential that can be comparable with commercialized liquid electrolyte system.展开更多
The electric double layer with the transmission of particles was presented based on the principle of electrochemistry.In accordance with this theory,the cavitation catalysis removal mechanism of ultrasonic-pulse elect...The electric double layer with the transmission of particles was presented based on the principle of electrochemistry.In accordance with this theory,the cavitation catalysis removal mechanism of ultrasonic-pulse electrochemical compound machining(UPECM) based on particles was proposed.The removal mechanism was a particular focus and was thus validated by experiments.The principles and experiments of UPECM were introduced,and the removal model of the UPECM based on the principles of UPECM was established.Furthermore,the effects of the material removal rate for the main processing parameters,including the particles size,the ultrasonic vibration amplitude,the pulse voltage and the minimum machining gap between the tool and the workpiece,were also studied through UPECM.The results show that the particles promote ultrasonic-pulse electrochemical compound machining and thus act as the catalyzer of UPECM.The results also indicate that the processing speed,machining accuracy and surface quality can be improved under UPECM compound machining.展开更多
Neutralization of alkaline properties of bauxite residue(BR)by using organic acid and gypsum additions may effectively improve electrochemical properties and alleviate physicochemical barriers to ecological rehabilita...Neutralization of alkaline properties of bauxite residue(BR)by using organic acid and gypsum additions may effectively improve electrochemical properties and alleviate physicochemical barriers to ecological rehabilitation.Mineral acids,citric acid and hybrid acid–gypsum additions were compared for their potential to transform and improve zeta potential,isoelectric point(IEP),surface protonation and active alkaline-OH groups,which are critical factors for further improvement of physicochemical and biological properties later.Isoelectric points of untransformed bauxite residue and six transformed derivatives were determined by using electroacoustic methods.Electrochemical characteristics were significantly improved by the amendments used,resulting in reduced IEP and-OH groups and decreased surface protonation for transformed residues.XRD results revealed that the primary alkaline minerals of cancrinite,calcite and grossular were transformed by the treatments.The treatments of citric acid and gypsum promoted the dissolution of cancrinite.From the SEM examination,citric acid and gypsum treatments contributed to the reduction in IEP and redistribution of-OH groups on particle surfaces.The collective evidence suggested that citric acid and gypsum amendments may be used firstly to rapidly amend bauxite residues for alleviating the caustic conditions prior to the consideration of soil formation in bauxite residue.展开更多
The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric a...The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric acid(HEDP),and tribasic ammonium citrate(TAC)were investigated by electrochemical techniques,X-ray photoelectron spectrometer(XPS)analysis,nano-scratch tests,AFM measurements,and polishing of Cu-coated blanket wafers.The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions,especially at pH=8.The optimal electrolyte compositions(mass fraction)are 6% HEDP,0.3% TTA and 3% TAC at pH=8.The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential.The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion.The surface topography evolution before and after electrochemical polishing(ECP)illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution,that is,the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate.This understanding is beneficial for optimization of ECMP processes.展开更多
Nucleation mechanism and technological process for Ni-Fe co-deposition with a relatively high Fe^(2+)concentration surrounded were described,and the effects of Fe^(2+) concentration,solution pH,temperature,and sodium ...Nucleation mechanism and technological process for Ni-Fe co-deposition with a relatively high Fe^(2+)concentration surrounded were described,and the effects of Fe^(2+) concentration,solution pH,temperature,and sodium dodecyl sulfonate concentration were investigated.Electrochemical experiments demonstrate that iron's electrodeposition plays a leading role in the Ni-Fe co-deposition process,and the co-deposition nucleation mechanism accords with a progressive nucleation.Temperature increase does favor in increasing nickel content in the ferronickel(Ni-Fe co-deposition products),while Fe^(2+) concentration increase does not.When solution pH is higher than 3.5,nickel content in the ferronickel decreases with pH because of the hydrolysis of Fe^(2+).With the current density of 180 A/m^2,Na_2SO_4 concentration of 100 g/L and Ni^(2+) concentration of 60 g/L,a smooth ferronickel deposit containing 96.21% Ni can be obtained under the conditions of temperature of 60 °C,Fe^(2+) concentration of 0.3 g/L,solution pH of 3 and sodium dodecyl sulfonate concentration of 40 mg/L.展开更多
文摘TP242.62 2001053743一种提高双目视觉测量精度的逐步逼近方法=A prograssive approach method for improving the accuracy of binocular vision measurement[刊,中]/双凯,董守平(石油大学机电学院.北京(102200))//光电工程.—2000,27(3).
文摘To investigate the overall performance of reverse energy bypass scramjet,firstly a variable spe⁃cific heat method combined with a chemical balance calculation module for combustion products were used to es⁃tablish a benchmark scramjet performance evaluation model.Based on the test data of typical flying point of Mach 7 with the altitude of 29 km,the reliability of the model was verified.The deviations of parameters such as the to⁃tal pressure loss of combustor between the model and the test data were analyzed.Furtherly,an analytical method for post-combustion magnetohydrodynamic power generation was established;by embedding the above method into the overall performance evaluation model,performance prediction considering the power generation effect was realized.Finally,based on the above model,variety regulations of the inlet and the outlet parameters of the power generation channel and performance parameters including the engine specific impulse and the unit thrust under different enthalpy extraction ratios and load factors were analyzed.It could be concluded that the model can reliably predict the variations of key parameters.As the value of the load factor increases,the value of the conduc⁃tivity required to reach the specified enthalpy extraction ratio first decreases and then increases,which is approxi⁃mately parabolic.In order to reduce the demand for the gas conductivity for MHD power generation,the load fac⁃tor should be around 0.5.When the load factor is 0.4 and the magnetic induction intensity is 2.5 T,if the enthalpy extraction ratio reaches 0.5%,the engine specific impulse performance reduces about 3.58%.
文摘We report an economical approach for the fabrication of laser-produced graphene(LPG)electrodes,which results in an improved electrochemical performance.Polyimide polymer was used as the starting material for LPG synthesis and was irradiated under ambient conditions with a CO_(2) laser.The prepared LPG samples were characterized by Raman spectroscopy and FTIR,which validated the formation of multilayer graphene containing sp2 hybridized C=C bonds.FE-SEM revealed three-dimensional(3D)sheet-like structures,while HR-TEM images showed lattice planes with an interplanar spacing of approximately 0.33 nm,corres-ponding to the(002)plane of graphene.Their electrochemical performance showed a remarkable areal specific capacitance(CA)of 51 mF cm^(−2)(170 F g^(-1))at 1 mA cm^(−2)(3.3 A g^(-1))in a three-electrode configuration with 1 mol L^(−1) KOH as the aqueous electrolyte.The LPG electrodes produced an energy density of~3.5μWh cm^(−2) and a power density of~350μW cm^(−2),demonstrating signific-ant energy storage ability.They also had an excellent cycling stability,retaining 87%of their specific capacitance after 3000 cycles at 1 mA/cm^(2).A symmetric supercapacitor fabricated with LPG electrodes and the 1 mol L^(−1) KOH electrolyte had a specific capacit-ance of 23 mF cm^(−2) and showed excellent retention after 10000 cycles,showing LPG’s potential for use in supercapacitors.
文摘The reverse magnetohydrodynamic(MHD)energy bypass technology is a promising energy redis⁃tribution technology in the scramjet system,in augmented with a power generation equipment to supply the neces⁃sary long-distance flight airframe power.In this paper,a computational model of the scramjet magnetohydrody⁃namic channel is developed and verified by using the commercial software Fluent.It is found that when the mag⁃netic induction intensity is 1,2,3,4 T,the power generation efficiency is 22.5%,22.3%,22.0%,21.5%,and decreases with the increase of the magnetic induction intensity,and the enthalpy extraction rate is 0.026%,0.1%,0.21%,0.34%,and increases with the increase of the magnetic induction intensity.The deceleration ef⁃fect of electromagnetic action on the airflow in the power channel increases with the increase of magnetic induc⁃tion intensity.The stronger the magnetic field intensity,the more obvious the decreasing effect of fluid Mach num⁃ber in the channel.The power generation efficiency decreases as the magnetic induction intensity increases and the enthalpy extraction rate is reversed.As the local currents gathering at inlet and outlet of the power generation area,total temperature and enthalpy along the flow direction do not vary linearly,and there are maximum and minimum values at inlet and outlet.Increasing the number of electrodes can effectively regulate the percentage of Joule heat dissipation,which can improve the power generation efficiency.
基金the support of the Grant-in-Aid for JSPS Research Fellow.
文摘All-solid-state lithium-ion batteries(LIBs)using ceramic electrolytes are considered the ideal form of rechargeable batteries due to their high energy density and safety.However,in the pursuit of all-solid-state LIBs,the issue of lithium resource availability is selectively overlooked.Considering that the amount of lithium required for all-solidstate LIBs is not sustainable with current lithium resources,another system that also offers the dual advantages of high energy density and safetydall-solid-state sodium-ion batteries(SIBs)dholds significant sustainable advantages and is likely to be the strong contender in the competition for developing next-generation high-energy-density batteries.This article briefly introduces the research status of all-solid-state SIBs,explains the sources of their advantages,and discusses potential approaches to the development of solid sodium-ion conductors,aiming to spark the interest of researchers and attract more attention to the field of all-solid-state SIBs.
基金Projects(51974368,51774333) supported by the National Natural Science Foundation of ChinaProject(2020JJ2048) supported by the Hunan Provincial Natural Science Foundation of China。
文摘With increasing demand on energy density of lithium-ion battery,wide electrochemical window and safety performance are the crucial request for next generation electrolyte.Gel-electrolyte as a pioneer for electrolyte solidization development aims to solve the safety and electrochemical window problems.However,low ionic conductivity and poor physical performance prohibit its further application.Herein,a fast-ionic conductor(Li_(2.64)(Sc_(0.9)Ti_(0.1))_(2)(PO_(4))_(3))(LSTP)was added into poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)base gel-electrolyte to enhance mechanical properties and ionic conductivity.Evidences reveal that LSTP was able to weaken interforce between polymer chains,which increased the ionic conductibility and decreased interface resistance during the cycling significantly.The obtained LiFePO_(4)/hybrid gel-electrolyte/Li-metal coin cell exhibited excellent rate capacity(145 mA·h/g at 1C,95 mA·h/g at 3C,28℃)which presented a potential that can be comparable with commercialized liquid electrolyte system.
基金Project(51275116)supported by the National Natural Science Foundation of ChinaProject(2012ZE77010)supported by the Aero Science Foundation of ChinaProject(LBH-Q11090)supported by the Postdoctoral Science Research Development Foundation of Heilongjiang Province,China
文摘The electric double layer with the transmission of particles was presented based on the principle of electrochemistry.In accordance with this theory,the cavitation catalysis removal mechanism of ultrasonic-pulse electrochemical compound machining(UPECM) based on particles was proposed.The removal mechanism was a particular focus and was thus validated by experiments.The principles and experiments of UPECM were introduced,and the removal model of the UPECM based on the principles of UPECM was established.Furthermore,the effects of the material removal rate for the main processing parameters,including the particles size,the ultrasonic vibration amplitude,the pulse voltage and the minimum machining gap between the tool and the workpiece,were also studied through UPECM.The results show that the particles promote ultrasonic-pulse electrochemical compound machining and thus act as the catalyzer of UPECM.The results also indicate that the processing speed,machining accuracy and surface quality can be improved under UPECM compound machining.
基金Projects(41877511,41842020)supported by the National Natural Science Foundation of China
文摘Neutralization of alkaline properties of bauxite residue(BR)by using organic acid and gypsum additions may effectively improve electrochemical properties and alleviate physicochemical barriers to ecological rehabilitation.Mineral acids,citric acid and hybrid acid–gypsum additions were compared for their potential to transform and improve zeta potential,isoelectric point(IEP),surface protonation and active alkaline-OH groups,which are critical factors for further improvement of physicochemical and biological properties later.Isoelectric points of untransformed bauxite residue and six transformed derivatives were determined by using electroacoustic methods.Electrochemical characteristics were significantly improved by the amendments used,resulting in reduced IEP and-OH groups and decreased surface protonation for transformed residues.XRD results revealed that the primary alkaline minerals of cancrinite,calcite and grossular were transformed by the treatments.The treatments of citric acid and gypsum promoted the dissolution of cancrinite.From the SEM examination,citric acid and gypsum treatments contributed to the reduction in IEP and redistribution of-OH groups on particle surfaces.The collective evidence suggested that citric acid and gypsum amendments may be used firstly to rapidly amend bauxite residues for alleviating the caustic conditions prior to the consideration of soil formation in bauxite residue.
基金Project(50975058)supported by the National Science Foundation of China
文摘The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric acid(HEDP),and tribasic ammonium citrate(TAC)were investigated by electrochemical techniques,X-ray photoelectron spectrometer(XPS)analysis,nano-scratch tests,AFM measurements,and polishing of Cu-coated blanket wafers.The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions,especially at pH=8.The optimal electrolyte compositions(mass fraction)are 6% HEDP,0.3% TTA and 3% TAC at pH=8.The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential.The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion.The surface topography evolution before and after electrochemical polishing(ECP)illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution,that is,the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate.This understanding is beneficial for optimization of ECMP processes.
基金Project(51574135)supported by the National Natural Science Foundation of ChinaProject(KKPT201563022)supported by Collaborative Innovation Center of Kunming University of Science and Technology,China
文摘Nucleation mechanism and technological process for Ni-Fe co-deposition with a relatively high Fe^(2+)concentration surrounded were described,and the effects of Fe^(2+) concentration,solution pH,temperature,and sodium dodecyl sulfonate concentration were investigated.Electrochemical experiments demonstrate that iron's electrodeposition plays a leading role in the Ni-Fe co-deposition process,and the co-deposition nucleation mechanism accords with a progressive nucleation.Temperature increase does favor in increasing nickel content in the ferronickel(Ni-Fe co-deposition products),while Fe^(2+) concentration increase does not.When solution pH is higher than 3.5,nickel content in the ferronickel decreases with pH because of the hydrolysis of Fe^(2+).With the current density of 180 A/m^2,Na_2SO_4 concentration of 100 g/L and Ni^(2+) concentration of 60 g/L,a smooth ferronickel deposit containing 96.21% Ni can be obtained under the conditions of temperature of 60 °C,Fe^(2+) concentration of 0.3 g/L,solution pH of 3 and sodium dodecyl sulfonate concentration of 40 mg/L.
