In case of manufacturing hexahedral ABS (Acrylonitrile Butadiene Styrene) plastic components using a FDM (Fused Deposition Modeling)-based 3D printer, undesirable shape errors occur in the product due to heat shrinkag...In case of manufacturing hexahedral ABS (Acrylonitrile Butadiene Styrene) plastic components using a FDM (Fused Deposition Modeling)-based 3D printer, undesirable shape errors occur in the product due to heat shrinkage. This paper experimentally ob-served the influence of the bed temperature change on the deformed shape errors of a hexahedral specimen of 100 × 50 × 50 mm3 produced by using a 3D printer. During printing work, the head nozzle temperature was kept at 240?C and the head speed was set at 50 mm/s. The chamber was enclosed with a PC-plate. 3D printing was conducted at four different bed temperatures;50?C, 70?C, 90?C, and 110?C. After the produced specimens naturally cooled down to room temperature, their deformed shape errors were measured. As a result, the higher the bed temperature, the lower the deformed shape errors of the specimens were. However, if the bed temperature had exceeded 120?C, laminating adhesion became poor. That seems to occur because of the material phase change and can make 3D printing work very hard as a consequence. Results of this study can be helpful to set optimum bed temperature condition in FDM additive manufacturing.展开更多
The neutral surface of a concave thin mirror is too close to the mirror surface,which makes it difficult to effectively mount the flexible structure and increases the mirror surface shape error.To address this problem...The neutral surface of a concave thin mirror is too close to the mirror surface,which makes it difficult to effectively mount the flexible structure and increases the mirror surface shape error.To address this problem,we design a flexible support structure including connectors,a support plate,and flexible structures,and construct an equivalent mirror by installing connectors and a support plate on the back of the mirror.While ensuring that the neutral surface of the equivalent mirror is moved away from the mirror surface,we optimize the support structure so that the rotary center of the flexible structure is located on the neutral surface of the equivalent mirror,avoiding the tilting moment.Following design and modeling of the structure,we analyze the static and dynamic characteristics using a finite element simulation,finding a root-mean-square(RMS)value for the surface shape error of 9.28 nm under the coupled effects of 1g gravity load,4℃ temperature rise,and 0.005 mm unevenness assembly error,with a fundamental frequency of 170.75 Hz,which all meet the design requirements.Finally,we carry out a surface shape error test of the mirror assembly,confirming it to meet the design index requirement of the mirror assembly.Simulation and test results verify the reliability and effectiveness of our proposed support structure.展开更多
The successive approximation register(SAR)is one of the most energy-efficient analog-to-digital converter(ADC)architecture for medium-resolution applications.However,its high energy efficiency quickly diminishes when ...The successive approximation register(SAR)is one of the most energy-efficient analog-to-digital converter(ADC)architecture for medium-resolution applications.However,its high energy efficiency quickly diminishes when the target resolution increases.This is because a SAR ADC suffers from several major error source,including the sampling kT/C noise,the comparator noise,and the DAC mismatch.These errors are increasing hard to address in high-resolution SAR ADCs.This paper reviews recent advances on error suppression techniques for SAR ADCs,including the sampling kT/C noise reduction,the noise-shaping(NS)SAR,and the mismatch error shaping(MES).These techniques aim to boost the resolution of SAR ADCs while maintaining their superior energy efficiency.展开更多
A V-shaped spacroscopic cell（V-cell） was constructed using two CaF2 optical plates for FTIR light transparent measurements in the range of 4000-1000 cm^（-1）.The spectrum of ethanol was characterized with the stand...A V-shaped spacroscopic cell（V-cell） was constructed using two CaF2 optical plates for FTIR light transparent measurements in the range of 4000-1000 cm^（-1）.The spectrum of ethanol was characterized with the standard spectra,excellent fitting was achieved with a bottom-width correction method.The principle of the V-cell was discussed,giving equations for the data interpretation.It shows that the V-cell is an auto-focus type spectroscopic cell,which can effectively avoid absorption saturation with amplifications for weak absorption bands.The V-cell design is simple and effective,easy to operate,suitable for applications in liquid samples with high absorption bands,willing to have broad application prospects.展开更多
This paper aims at analyzing the shapes of the bounded traveling wave solu- tions for a class of nonlinear wave equation with a quintic term and obtaining its damped oscillatory solutions. The theory and method of pla...This paper aims at analyzing the shapes of the bounded traveling wave solu- tions for a class of nonlinear wave equation with a quintic term and obtaining its damped oscillatory solutions. The theory and method of planar dynamical systems are used to make a qualitative analysis to the planar dynamical system which the bounded traveling wave solutions of this equation correspond to. The shapes, existent number, and condi- tions are presented for all bounded traveling wave solutions. The bounded traveling wave solutions are obtained by the undetermined coefficients method according to their shapes, including exact expressions of bell and kink profile solitary wave solutions and approxi- mate expressions of damped oscillatory solutions. For the approximate damped oscillatory solution, using the homogenization principle, its error estimate is given by establishing the integral equation, which reflects the relation between the exact and approximate so- lutions. It can be seen that the error is infinitesimal decreasing in the exponential form.展开更多
文摘In case of manufacturing hexahedral ABS (Acrylonitrile Butadiene Styrene) plastic components using a FDM (Fused Deposition Modeling)-based 3D printer, undesirable shape errors occur in the product due to heat shrinkage. This paper experimentally ob-served the influence of the bed temperature change on the deformed shape errors of a hexahedral specimen of 100 × 50 × 50 mm3 produced by using a 3D printer. During printing work, the head nozzle temperature was kept at 240?C and the head speed was set at 50 mm/s. The chamber was enclosed with a PC-plate. 3D printing was conducted at four different bed temperatures;50?C, 70?C, 90?C, and 110?C. After the produced specimens naturally cooled down to room temperature, their deformed shape errors were measured. As a result, the higher the bed temperature, the lower the deformed shape errors of the specimens were. However, if the bed temperature had exceeded 120?C, laminating adhesion became poor. That seems to occur because of the material phase change and can make 3D printing work very hard as a consequence. Results of this study can be helpful to set optimum bed temperature condition in FDM additive manufacturing.
基金supported by the National Natural Science Foundation of China(12473085).
文摘The neutral surface of a concave thin mirror is too close to the mirror surface,which makes it difficult to effectively mount the flexible structure and increases the mirror surface shape error.To address this problem,we design a flexible support structure including connectors,a support plate,and flexible structures,and construct an equivalent mirror by installing connectors and a support plate on the back of the mirror.While ensuring that the neutral surface of the equivalent mirror is moved away from the mirror surface,we optimize the support structure so that the rotary center of the flexible structure is located on the neutral surface of the equivalent mirror,avoiding the tilting moment.Following design and modeling of the structure,we analyze the static and dynamic characteristics using a finite element simulation,finding a root-mean-square(RMS)value for the surface shape error of 9.28 nm under the coupled effects of 1g gravity load,4℃ temperature rise,and 0.005 mm unevenness assembly error,with a fundamental frequency of 170.75 Hz,which all meet the design requirements.Finally,we carry out a surface shape error test of the mirror assembly,confirming it to meet the design index requirement of the mirror assembly.Simulation and test results verify the reliability and effectiveness of our proposed support structure.
基金supported by National Natural Science Foundation of China(No.61904094,No.61934009)China Postdoctoral Science Foundation(No.2020M670329)Beijing Innovation Center for Future Chips(ICFC).
文摘The successive approximation register(SAR)is one of the most energy-efficient analog-to-digital converter(ADC)architecture for medium-resolution applications.However,its high energy efficiency quickly diminishes when the target resolution increases.This is because a SAR ADC suffers from several major error source,including the sampling kT/C noise,the comparator noise,and the DAC mismatch.These errors are increasing hard to address in high-resolution SAR ADCs.This paper reviews recent advances on error suppression techniques for SAR ADCs,including the sampling kT/C noise reduction,the noise-shaping(NS)SAR,and the mismatch error shaping(MES).These techniques aim to boost the resolution of SAR ADCs while maintaining their superior energy efficiency.
文摘A V-shaped spacroscopic cell（V-cell） was constructed using two CaF2 optical plates for FTIR light transparent measurements in the range of 4000-1000 cm^（-1）.The spectrum of ethanol was characterized with the standard spectra,excellent fitting was achieved with a bottom-width correction method.The principle of the V-cell was discussed,giving equations for the data interpretation.It shows that the V-cell is an auto-focus type spectroscopic cell,which can effectively avoid absorption saturation with amplifications for weak absorption bands.The V-cell design is simple and effective,easy to operate,suitable for applications in liquid samples with high absorption bands,willing to have broad application prospects.
基金Project supported by the National Natural Science Foundation of China(No.11071164)the Innovation Program of Shanghai Municipal Education Commission(No.13ZZ118)+1 种基金the Shanghai Leading Academic Discipline Project(No.XTKX2012)the Innovation Fund Project for Graduate Stu-dent of Shanghai(No.JWCXSL1201)
文摘This paper aims at analyzing the shapes of the bounded traveling wave solu- tions for a class of nonlinear wave equation with a quintic term and obtaining its damped oscillatory solutions. The theory and method of planar dynamical systems are used to make a qualitative analysis to the planar dynamical system which the bounded traveling wave solutions of this equation correspond to. The shapes, existent number, and condi- tions are presented for all bounded traveling wave solutions. The bounded traveling wave solutions are obtained by the undetermined coefficients method according to their shapes, including exact expressions of bell and kink profile solitary wave solutions and approxi- mate expressions of damped oscillatory solutions. For the approximate damped oscillatory solution, using the homogenization principle, its error estimate is given by establishing the integral equation, which reflects the relation between the exact and approximate so- lutions. It can be seen that the error is infinitesimal decreasing in the exponential form.
