Expanding the specific surface area of substrates and carrying out precise surface engineering of imprinted nanocavities are crucial methods for enhancing the identification efficiency of molecularly imprinted polymer...Expanding the specific surface area of substrates and carrying out precise surface engineering of imprinted nanocavities are crucial methods for enhancing the identification efficiency of molecularly imprinted polymers(MIPs).To implement this synergistic strategy,bioinspired surface engineering was used to incorporate dual covalent receptors via precise post-imprinting modifications(PIMs)onto mesoporous silica nanosheets.The prepared sorbents(denoted as‘‘D-PMIPs”)were utilized to improve the specific identification of adenosine 5-monophosphate(AMP).Significantly,the mesoporous silica nanosheets possess a high surface area of approximately 498.73 m^(2)·g^(-1),which facilitates the formation of abundant specific recognition sites in the D-PMIPs.The dual covalent receptors are valuable for estab-lishing the spatial orientation and arrangement of AMP through multiple cooperative interactions.PIMs enable precise site-specific functionalization within the imprinted cavities,leading to the tailor-made formation of complementary binding sites.The maximum number of high-affinity binding sites(Nmax)of the D-PMIPs is 39.99 lmol·g^(-1),which is significantly higher than that of imprinted sorbents with a sin-gle receptor(i.e.,S-BMIPs or S-PMIPs).The kinetic data of the D-PMIPs can be effectively described by a pseudo-second-order model,indicating that the main binding mechanism involves synergistic chemisorption from boronate affinity and the pyrimidine base.This study suggests that using dual cova-lent receptors and PIMs is a reliable approach for creating imprinted sorbents with high selectivity,allow-ing for the controlled engineering of imprinted sites.展开更多
Optical glass elements with the ellipsoidal surface are used in many critical aerospace instruments,such as satellites,telescope and cameras.Their optical performance is mainly affected by profile accuracy and surface...Optical glass elements with the ellipsoidal surface are used in many critical aerospace instruments,such as satellites,telescope and cameras.Their optical performance is mainly affected by profile accuracy and surface quality.In this paper,a rectangular ellipsoid surface is precisely ground on a BK7 optical glass blank by grating scanning grinding path with a three-axis CNC precision surface grinder.A profile error compensation procedure for ellipsoidal grinding is proposed based on the error analysis about the primary error sources in the XY and YZ projection planes during the grinding process.The mathematical prediction models of the wheel arc profile error,the measurement and wear error of the grinding wheel radiuses are established.By applying the proposed error compensation procedure,the profile accuracy of the ellipsoidal surface was improved from 4 lm to 2 lm in the XY plane,and improved from 15 lm to 5 lm in the YZ plane.展开更多
A discretization precision control method based on the second order osculating surface is proposed. The discretization precision of 3 D solid is controlled according to the error between the discrete solid surface a...A discretization precision control method based on the second order osculating surface is proposed. The discretization precision of 3 D solid is controlled according to the error between the discrete solid surface and its second order osculating surface. The global maximal error has been gotten after analyzing all the extremums of the error function. It can be used in controlling and optimizing the discretization precision of 3 D solid in computer 3 D modeling and NC milling path generation.展开更多
Ultra-precision machining causes materials to undergo a greatly strained deformation process in a short period of time.The effect of shear strain rates on machining quality, in particular on surface anisotropy, is a t...Ultra-precision machining causes materials to undergo a greatly strained deformation process in a short period of time.The effect of shear strain rates on machining quality, in particular on surface anisotropy, is a topic deserving of research that has thus far been overlooked.This study analyzes the impact of the strain rate during the ultra-precision turning of single-crystal silicon on the anisotropy of surface roughness.Focusing on the establishment of cutting models considering the tool rake angle and the edge radius, this is the first research that takes into account the strain rate dislocation emission criteria in studying the effects of the edge radius, the cutting speed, and the cutting thickness on the plastic deformation of single-crystal silicon.The results of this study show that the uses of a smaller edge radius, faster cutting speeds, and a reduced cutting thickness can result in optimally uniform surface roughness, while the use of a very sharp cutting tool is essential when operating with smaller cutting thicknesses.A further finding is that insufficient plastic deformation is the major cause of increased surface roughness in the ultra-precision turning of brittle materials.On this basis, we propose that the capacity of single-crystal silicon to emit dislocations be improved as much as possible before brittle fracture occurs, thereby promoting plastic deformation and minimizing the anisotropy of surface roughness in the machined workpiece.展开更多
To aim at prototype parts fabricated with fused deposition modeling （FDM） process, the problems how to improve and enhance their surface micro-precision are studied. The producing mechanism of surface roughness is e...To aim at prototype parts fabricated with fused deposition modeling （FDM） process, the problems how to improve and enhance their surface micro-precision are studied. The producing mechanism of surface roughness is explained with three aspects concretely including the principle error of rapid prototyping （RP） process, the inherent characteristics of FDM process, and some mi- cro-scratches on the surface of the extruded fiber. Based on the micro-characters of section shape of the FDM prototype, a physical model reflecting the outer shape characters is abstracted. With the physical simplified and deduced, the evaluating equations of surface roughness are acquired. According to the FDM sample parts with special design for experimental measurement, the real surface roughness values of different inclined planes are obtained. And the measuring values of surface roughness are compared with the calculation values. Furthermore, the causes of surface roughness deviation between measuring values and calculation values are respectively analyzed and studied. With the references of analytic conclusions, the measuring values of the experimental part surface are revised, and the revised values nearly accord with the calculation values. Based on the influencing principles of FDM process parameters and special post processing of FDM prototype parts, some concrete measures are proposed to reduce the surface roughness of FDM parts, and the applying effects are better.展开更多
We developed a measuring instrument that had wide range, high precision, small measuring touch force. The instrument for three-dimensional (3D) surface topography measurement was composed of a high precision displacem...We developed a measuring instrument that had wide range, high precision, small measuring touch force. The instrument for three-dimensional (3D) surface topography measurement was composed of a high precision displacement sensor based on the Michelson interference principle, a 3D platform based on vertical scanning, a measuring and control circuit, and an industrial control computer. It was a closed loop control system, which changed the traditional moving stylus scanning style into a moving platform scanning style. When the workpiece was measured, the lever of the displacement sensor returned to the balanced position in every sample interval according to the zero offset of the displacement sensor. The non-linear error caused by the rotation of the lever was, therefore, very small even if the measuring range was wide. The instrument can measure the roughness and the profile size of a curved surface.展开更多
Due to the excellent self-centering and load-carrying capability,curvic couplings have been widely used in advanced aero-engine rotors.However,curvic tooth surface errors lead to poor assembly precision.Traditional ph...Due to the excellent self-centering and load-carrying capability,curvic couplings have been widely used in advanced aero-engine rotors.However,curvic tooth surface errors lead to poor assembly precision.Traditional physical-master-gauge-based indirect tooth surface error measurement and circumferential assembly angle optimization methods have the disadvantages of high cost and weak generality.The unknown tooth surface fitting mechanism is a big barrier to assembly precision prediction and improvement.Therefore,this work puts forward a data-driven assembly simulation and optimization approach for aero-engine rotors connected by curvic couplings.The origin of curvic tooth surface error is deeply investigated.Using 5-axis sweep scan method,a large amount of high-precision curvic tooth surface data are acquired efficiently.Based on geometric models of parts,the fitting mechanism of curvic couplings is uncovered for assembly precision simulation and prediction.A circumferential assembly angle optimization model is developed to decrease axial and radial assembly runouts.Experimental results show that the assembly precision can be predicted accurately and improved dramatically.By uncovering the essential principle of the assembly precision formation and proposing circumferential assembly angle optimization model,this work is meaningful for assembly quality,efficiency and economy improvement of multistage aero-engine rotors connected by curvic couplings.展开更多
Global navigation satellite system-reflection(GNSS-R)sea surface altimetry based on satellite constellation platforms has become a new research direction and inevitable trend,which can meet the altimetric precision at...Global navigation satellite system-reflection(GNSS-R)sea surface altimetry based on satellite constellation platforms has become a new research direction and inevitable trend,which can meet the altimetric precision at the global scale required for underwater navigation.At present,there are still research gaps for GNSS-R altimetry under this mode,and its altimetric capability cannot be specifically assessed.Therefore,GNSS-R satellite constellations that meet the global altimetry needs to be designed.Meanwhile,the matching precision prediction model needs to be established to quantitatively predict the GNSS-R constellation altimetric capability.Firstly,the GNSS-R constellations altimetric precision under different configuration parameters is calculated,and the mechanism of the influence of orbital altitude,orbital inclination,number of satellites and simulation period on the precision is analyzed,and a new multilayer feedforward neural network weighted joint prediction model is established.Secondly,the fit of the prediction model is verified and the performance capability of the model is tested by calculating the R2 value of the model as 0.9972 and the root mean square error(RMSE)as 0.0022,which indicates that the prediction capability of the model is excellent.Finally,using the novel multilayer feedforward neural network weighted joint prediction model,and considering the research results and realistic costs,it is proposed that when the constellation is set to an orbital altitude of 500 km,orbital inclination of 75and the number of satellites is 6,the altimetry precision can reach 0.0732 m within one year simulation period,which can meet the requirements of underwater navigation precision,and thus can provide a reference basis for subsequent research on spaceborne GNSS-R sea surface altimetry.展开更多
单晶硅作为常用的红外光学材料,随着红外技术的不断发展,对光学元件的质量要求也越来越高。为了获得高面形精度、高表面质量的复杂曲面单晶硅光学元件,提出了激光原位辅助超精密车削、磁流变和小磨头抛光组合抛光修形的短流程加工工艺...单晶硅作为常用的红外光学材料,随着红外技术的不断发展,对光学元件的质量要求也越来越高。为了获得高面形精度、高表面质量的复杂曲面单晶硅光学元件,提出了激光原位辅助超精密车削、磁流变和小磨头抛光组合抛光修形的短流程加工工艺。采用激光原位辅助超精密车削加工后的单晶硅元件具有低亚表面损伤,与未加激光时相比,激光原位辅助超精密车削后的单晶硅亚表面损伤由920 n m降低至318 nm。并经过多轮磁流变和小磨头抛光组合工艺迭代加工后,单晶硅光学元件面形精度和表面质量得到有效提升,最终面形精度RMS值优于1/50λ,表面粗糙度Ra值优于0.5 nm。该方法抑制了加工过程中的亚表面损伤,减少了后续抛光过程中损伤去除时间,有效提高了单晶硅光学元件加工效率,且面形精度和表面质量可满足高精度光学元件应用要求。展开更多
基金supported by the National Natural Science Foundation of China(22078132,22108103,and U22A20413)the Open Funding Project of the National Key Labora-tory of Biochemical Engineering(2021KF-02)+3 种基金China Postdoctoral Science Foundation(2021M691301)Jiangsu Key Research and Development Program(BE2022356)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(CPSF)(GZ20230989)Jiangsu Agricultural Independent Innovation Fund Project(CX(21)3079).
文摘Expanding the specific surface area of substrates and carrying out precise surface engineering of imprinted nanocavities are crucial methods for enhancing the identification efficiency of molecularly imprinted polymers(MIPs).To implement this synergistic strategy,bioinspired surface engineering was used to incorporate dual covalent receptors via precise post-imprinting modifications(PIMs)onto mesoporous silica nanosheets.The prepared sorbents(denoted as‘‘D-PMIPs”)were utilized to improve the specific identification of adenosine 5-monophosphate(AMP).Significantly,the mesoporous silica nanosheets possess a high surface area of approximately 498.73 m^(2)·g^(-1),which facilitates the formation of abundant specific recognition sites in the D-PMIPs.The dual covalent receptors are valuable for estab-lishing the spatial orientation and arrangement of AMP through multiple cooperative interactions.PIMs enable precise site-specific functionalization within the imprinted cavities,leading to the tailor-made formation of complementary binding sites.The maximum number of high-affinity binding sites(Nmax)of the D-PMIPs is 39.99 lmol·g^(-1),which is significantly higher than that of imprinted sorbents with a sin-gle receptor(i.e.,S-BMIPs or S-PMIPs).The kinetic data of the D-PMIPs can be effectively described by a pseudo-second-order model,indicating that the main binding mechanism involves synergistic chemisorption from boronate affinity and the pyrimidine base.This study suggests that using dual cova-lent receptors and PIMs is a reliable approach for creating imprinted sorbents with high selectivity,allow-ing for the controlled engineering of imprinted sites.
基金National Natural Science Foundation of China(no.51875321)Shandong Provincial Natural Science Foundation(no.ZR2018MEE019)Major Basic Research of Shandong Provincial Natural Science Foundation(no.ZR2018ZB0521,ZR2018ZA0401)。
文摘Optical glass elements with the ellipsoidal surface are used in many critical aerospace instruments,such as satellites,telescope and cameras.Their optical performance is mainly affected by profile accuracy and surface quality.In this paper,a rectangular ellipsoid surface is precisely ground on a BK7 optical glass blank by grating scanning grinding path with a three-axis CNC precision surface grinder.A profile error compensation procedure for ellipsoidal grinding is proposed based on the error analysis about the primary error sources in the XY and YZ projection planes during the grinding process.The mathematical prediction models of the wheel arc profile error,the measurement and wear error of the grinding wheel radiuses are established.By applying the proposed error compensation procedure,the profile accuracy of the ellipsoidal surface was improved from 4 lm to 2 lm in the XY plane,and improved from 15 lm to 5 lm in the YZ plane.
文摘A discretization precision control method based on the second order osculating surface is proposed. The discretization precision of 3 D solid is controlled according to the error between the discrete solid surface and its second order osculating surface. The global maximal error has been gotten after analyzing all the extremums of the error function. It can be used in controlling and optimizing the discretization precision of 3 D solid in computer 3 D modeling and NC milling path generation.
基金supported by the National Defence Scientific Research of China (A3520133004)
文摘Ultra-precision machining causes materials to undergo a greatly strained deformation process in a short period of time.The effect of shear strain rates on machining quality, in particular on surface anisotropy, is a topic deserving of research that has thus far been overlooked.This study analyzes the impact of the strain rate during the ultra-precision turning of single-crystal silicon on the anisotropy of surface roughness.Focusing on the establishment of cutting models considering the tool rake angle and the edge radius, this is the first research that takes into account the strain rate dislocation emission criteria in studying the effects of the edge radius, the cutting speed, and the cutting thickness on the plastic deformation of single-crystal silicon.The results of this study show that the uses of a smaller edge radius, faster cutting speeds, and a reduced cutting thickness can result in optimally uniform surface roughness, while the use of a very sharp cutting tool is essential when operating with smaller cutting thicknesses.A further finding is that insufficient plastic deformation is the major cause of increased surface roughness in the ultra-precision turning of brittle materials.On this basis, we propose that the capacity of single-crystal silicon to emit dislocations be improved as much as possible before brittle fracture occurs, thereby promoting plastic deformation and minimizing the anisotropy of surface roughness in the machined workpiece.
基金This project is supported by National Natural Science Foundation of China (No. 50575139)
文摘To aim at prototype parts fabricated with fused deposition modeling （FDM） process, the problems how to improve and enhance their surface micro-precision are studied. The producing mechanism of surface roughness is explained with three aspects concretely including the principle error of rapid prototyping （RP） process, the inherent characteristics of FDM process, and some mi- cro-scratches on the surface of the extruded fiber. Based on the micro-characters of section shape of the FDM prototype, a physical model reflecting the outer shape characters is abstracted. With the physical simplified and deduced, the evaluating equations of surface roughness are acquired. According to the FDM sample parts with special design for experimental measurement, the real surface roughness values of different inclined planes are obtained. And the measuring values of surface roughness are compared with the calculation values. Furthermore, the causes of surface roughness deviation between measuring values and calculation values are respectively analyzed and studied. With the references of analytic conclusions, the measuring values of the experimental part surface are revised, and the revised values nearly accord with the calculation values. Based on the influencing principles of FDM process parameters and special post processing of FDM prototype parts, some concrete measures are proposed to reduce the surface roughness of FDM parts, and the applying effects are better.
基金the National Science Foundation of China (No.50745020).
文摘We developed a measuring instrument that had wide range, high precision, small measuring touch force. The instrument for three-dimensional (3D) surface topography measurement was composed of a high precision displacement sensor based on the Michelson interference principle, a 3D platform based on vertical scanning, a measuring and control circuit, and an industrial control computer. It was a closed loop control system, which changed the traditional moving stylus scanning style into a moving platform scanning style. When the workpiece was measured, the lever of the displacement sensor returned to the balanced position in every sample interval according to the zero offset of the displacement sensor. The non-linear error caused by the rotation of the lever was, therefore, very small even if the measuring range was wide. The instrument can measure the roughness and the profile size of a curved surface.
基金co-supported by the National Basic Research Project(Nos.J2022-VII-0001-0043 and 2017-VII-0010-0104)the Fundamental Research Funds for the Central Universities,and the National Natural Science Foundation of China(No.72231008)。
文摘Due to the excellent self-centering and load-carrying capability,curvic couplings have been widely used in advanced aero-engine rotors.However,curvic tooth surface errors lead to poor assembly precision.Traditional physical-master-gauge-based indirect tooth surface error measurement and circumferential assembly angle optimization methods have the disadvantages of high cost and weak generality.The unknown tooth surface fitting mechanism is a big barrier to assembly precision prediction and improvement.Therefore,this work puts forward a data-driven assembly simulation and optimization approach for aero-engine rotors connected by curvic couplings.The origin of curvic tooth surface error is deeply investigated.Using 5-axis sweep scan method,a large amount of high-precision curvic tooth surface data are acquired efficiently.Based on geometric models of parts,the fitting mechanism of curvic couplings is uncovered for assembly precision simulation and prediction.A circumferential assembly angle optimization model is developed to decrease axial and radial assembly runouts.Experimental results show that the assembly precision can be predicted accurately and improved dramatically.By uncovering the essential principle of the assembly precision formation and proposing circumferential assembly angle optimization model,this work is meaningful for assembly quality,efficiency and economy improvement of multistage aero-engine rotors connected by curvic couplings.
基金the National Natural Science Foundation of China under Grant(42274119)the Liaoning Revitalization Talents Program under Grant(XLYC2002082)+1 种基金National Key Research and Development Plan Key Special Projects of Science and Technology Military Civil Integration(2022YFF1400500)the Key Project of Science and Technology Commission of the Central Military Commission.
文摘Global navigation satellite system-reflection(GNSS-R)sea surface altimetry based on satellite constellation platforms has become a new research direction and inevitable trend,which can meet the altimetric precision at the global scale required for underwater navigation.At present,there are still research gaps for GNSS-R altimetry under this mode,and its altimetric capability cannot be specifically assessed.Therefore,GNSS-R satellite constellations that meet the global altimetry needs to be designed.Meanwhile,the matching precision prediction model needs to be established to quantitatively predict the GNSS-R constellation altimetric capability.Firstly,the GNSS-R constellations altimetric precision under different configuration parameters is calculated,and the mechanism of the influence of orbital altitude,orbital inclination,number of satellites and simulation period on the precision is analyzed,and a new multilayer feedforward neural network weighted joint prediction model is established.Secondly,the fit of the prediction model is verified and the performance capability of the model is tested by calculating the R2 value of the model as 0.9972 and the root mean square error(RMSE)as 0.0022,which indicates that the prediction capability of the model is excellent.Finally,using the novel multilayer feedforward neural network weighted joint prediction model,and considering the research results and realistic costs,it is proposed that when the constellation is set to an orbital altitude of 500 km,orbital inclination of 75and the number of satellites is 6,the altimetry precision can reach 0.0732 m within one year simulation period,which can meet the requirements of underwater navigation precision,and thus can provide a reference basis for subsequent research on spaceborne GNSS-R sea surface altimetry.
文摘单晶硅作为常用的红外光学材料,随着红外技术的不断发展,对光学元件的质量要求也越来越高。为了获得高面形精度、高表面质量的复杂曲面单晶硅光学元件,提出了激光原位辅助超精密车削、磁流变和小磨头抛光组合抛光修形的短流程加工工艺。采用激光原位辅助超精密车削加工后的单晶硅元件具有低亚表面损伤,与未加激光时相比,激光原位辅助超精密车削后的单晶硅亚表面损伤由920 n m降低至318 nm。并经过多轮磁流变和小磨头抛光组合工艺迭代加工后,单晶硅光学元件面形精度和表面质量得到有效提升,最终面形精度RMS值优于1/50λ,表面粗糙度Ra值优于0.5 nm。该方法抑制了加工过程中的亚表面损伤,减少了后续抛光过程中损伤去除时间,有效提高了单晶硅光学元件加工效率,且面形精度和表面质量可满足高精度光学元件应用要求。
