The service cycle and dynamic performance of structural parts are afected by the weld grinding accuracy and surface consistency. Because of reasons such as assembly errors and thermal deformation, the actual track of ...The service cycle and dynamic performance of structural parts are afected by the weld grinding accuracy and surface consistency. Because of reasons such as assembly errors and thermal deformation, the actual track of the robot does not coincide with the theoretical track when the weld is ground ofine, resulting in poor workpiece surface quality. Considering these problems, in this study, a vision sensing-based online correction system for robotic weld grinding was developed. The system mainly included three subsystems: weld feature extraction, grinding, and robot real-time control. The grinding equipment was frst set as a substation for the robot using the WorkVisual software. The input/output (I/O) ports for communication between the robot and the grinding equipment were confgured via the I/O mapping function to enable the robot to control the grinding equipment (start, stop, and speed control). Subsequently, the Ethernet KRL software package was used to write the data interaction structure to realize realtime communication between the robot and the laser vision system. To correct the measurement error caused by the bending deformation of the workpiece, we established a surface profle model of the base material in the weld area using a polynomial ftting algorithm to compensate for the measurement data. The corrected extracted weld width and height errors were reduced by 2.01% and 9.3%, respectively. Online weld seam extraction and correction experiments verifed the efectiveness of the system’s correction function, and the system could control the grinding trajectory error within 0.2 mm. The reliability of the system was verifed through actual weld grinding experiments. The roughness, Ra, could reach 0.504 µm and the average residual height was within 0.21 mm. In this study, we developed a vision sensing-based online correction system for robotic weld grinding with a good correction efect and high robustness.展开更多
The energy consumption of distillation operation determines the amount of energy consumption throughout the chemical separation process. A heat integrated distillation column(HIDiC) could greatly reduce the irreversib...The energy consumption of distillation operation determines the amount of energy consumption throughout the chemical separation process. A heat integrated distillation column(HIDiC) could greatly reduce the irreversibility of the distillation process, so it gradually becomes a research hotspot. There are two major techniques for heat integration in HIDiC: internally and externally. This review paper describes the major research aspects of an internally heat integrated distillation column(IHIDiC), including the heat transfer models, various design structures(including the two-column HIDiC, Concentric HIDiC, Shell and tube HIDiC, Plate-fin HIDiC and the Super HIDiC, etc.), experimental research, simulation and optimization, process control research, as well as industrial plants and potential industrial applications. Among them, the heat transfer performance of various structures was analyzed of the various design structures based on experimental research, the effects of different factors(including relative volatility, reflux ratio, compression ratio, etc.) on HIDiC energy consumption or TAC is summarized in the simulation part. The calculation methods of the overall heat transfer coefficient and heat transfer models are summarized. The various optimization algorithms and optimization results of simplified HIDiC are summarized in the optimization part. The research status and the key technical issues in various aspects of HIDiC are summarized in this paper. In order to meet the requirements of industrial energy efficiency,the selection of multi-component separation distillation configurations needs to be considered more diversified,and internal complex coupling relationship of HIDiC needs to be further studied.展开更多
We propose a novel scheme for THz wave generation by repeated and continuous frequency conversions from pump wave to high-order Stokes waves(HSWs).The repeated frequency conversions are accomplished by oscillations of...We propose a novel scheme for THz wave generation by repeated and continuous frequency conversions from pump wave to high-order Stokes waves(HSWs).The repeated frequency conversions are accomplished by oscillations of Stoke waves in resonant cavity(RC)where low-order Stokes waves(LSWs)are converted to high-order Stokes waves again and again.The continuous frequency conversions are accomplished by optimized cascaded difference frequency generation(OCDFG)where the poling periods of the optical crystal are aperiodic leading to the frequency conversions from low-order Stokes waves to high-order Stokes waves uninterruptedly and unidirectionally.Combined with the repeated and continuous frequency conversions,the optical-to-THz energy conversion efficiency(OTECE)exceeds 26%at 300 K and 43%at 100 K with pump intensities of 300 MW/cm^(2).展开更多
The optical control ability of photonic crystal fiber(PCF)is a distinctive property suitable for improving sensing and plasma performance.This article proposes a dual-core D-channel PCF sensor that can detect two samp...The optical control ability of photonic crystal fiber(PCF)is a distinctive property suitable for improving sensing and plasma performance.This article proposes a dual-core D-channel PCF sensor that can detect two samples simultaneously,which effectively solves the problems of coating difficulty and low wavelength sensitivity.The PCF has four layers of air holes,which dramatically reduces the optical fiber loss and is more conducive to the application of sensors in actual production.In addition,by introducing dual cores on the upper and lower sides of the central air hole,reducing the spacing between the core and the gold nanolayer,a stronger evanescent field can be generated in the cladding air hole.The optical fiber sensor can detect the refractive index of two samples simultaneously with a maximum sensitivity of 21300 nm/RIU.To the best of our knowledge,the sensitivity achieved in this work is the highest sensitivity with the dual sample synchronous detection sensors.The detection range of the refraction index is 1.35-1.41,and the resolution of the sensor is 4.695×10^(-6).Overall,the sensor will be suitable for medical detection,organic chemical sensing,analyte detection,and other fields.展开更多
High-efficiency terahertz(THz) wave generation with multiple frequencies by optimized cascaded difference frequency generation(OCDFG) is investigated at 100 K using a nonlinear crystal consisting of a periodically pol...High-efficiency terahertz(THz) wave generation with multiple frequencies by optimized cascaded difference frequency generation(OCDFG) is investigated at 100 K using a nonlinear crystal consisting of a periodically poled lithium niobate(PPLN) part and an aperiodically poled lithium niobate(APPLN) part.Two infrared pump waves with a frequency difference ω_(T1) generate THz waves and a series of cascaded optical waves in the PPLN part by cascaded difference frequency generation(CDFG).The generated cascaded optical waves with frequency interval ω_(T1) then further interact in the APPLN part by OCDFG,yielding the following two advantages.First,OCDFG in the APPLN part is efficiently stimulated by inputting multi-order cascaded optical waves rather than the only two intense infrared pump waves,yielding unprecedented energy conversion efficiencies in excess of 37% at 1 THz at 100 K.Second,THz waves with M timesω_(T1) are generated by mixing the mth-order and the(m+M)th-order cascaded optical waves by designing poling period distributions of the APPLN part.展开更多
A novel scheme for high-efficiency terahertz(THz)wave generation based on optimized cascaded difference frequency generation(OCDFG)with planar waveguide is presented.The phase mismatches of each-order cascaded differe...A novel scheme for high-efficiency terahertz(THz)wave generation based on optimized cascaded difference frequency generation(OCDFG)with planar waveguide is presented.The phase mismatches of each-order cascaded difference frequency generation(CDFG)are modulated by changing the thickness of the waveguide,resulting in a decrement of phase mismatches in cascaded Stokes processes and an increment of phase mismatches in cascaded anti-Stokes processes simultaneously.The modulated phase mismatches enhance the cascaded Stokes processes and suppress the cascaded anti-Stokes processes simultaneously,yielding energy conversion efficiencies over 25%from optical wave to THz wave at 100 K.展开更多
Metal-organic framework(MOF)-on-MOF structure allows stacking various types of MOFs with different lattice constants for molecule sieving or filtering.However,the multilayered MOFs-based optical devices have incoheren...Metal-organic framework(MOF)-on-MOF structure allows stacking various types of MOFs with different lattice constants for molecule sieving or filtering.However,the multilayered MOFs-based optical devices have incoherent interference due to the lattice-mismatch at the interface and refractive index(RI)indifference.This paper reports isostructural MOFs-based photonic crystals(PCs)designed by stacking Bragg bilayers of lattice-matched MOFs thin films through a layer-by-layer assembly method.Colloidal nanoparticles(NPs)were homogenously encapsulated in some layers of the MOFs(HKUST-1@NPs)to tune their intrinsic RI during the spraying coating process.The isostructural MOFs-based PCs were constructed on a large scale by sequentially spraying coating the low RI layer of HKUST-1 and high RI layer of HKUST-1@NPs to form the desired number of Bragg bilayers.X-ray photoelectron spectroscopy(XPS)depth profiling proved the Bragg bilayers and the homogenous encapsulation of nanomaterials in certain layers of MOFs.Bandwidth of the PCs was tailored by the thickness and RI of the Bragg bilayers,which had a great consistent with finite difference time domain(FDTD)simulation.Importantly,reflectivity of the isostructural MOFs-based PCs was up to 96%.We demonstrated high detection sensitivity for chemical sensing on the PCs,which could be advanced by encapsulating different types of nanomaterials and designing wide-band isostructural MOFs-based PCs.展开更多
Polarization optics plays a pivotal role in diffractive,refractive,and emerging flat optics,and has been widely employed in contemporary optical industries and daily life.Advanced polarization manipulation leads to ro...Polarization optics plays a pivotal role in diffractive,refractive,and emerging flat optics,and has been widely employed in contemporary optical industries and daily life.Advanced polarization manipulation leads to robust control of the polarization direction of light.Nevertheless,polarization control has been studied largely independent of the phase or intensity of light.Here,we propose and experimentally validate a Malus-metasurface-assisted paradigm to enable simultaneous and independent control of the intensity and phase properties of light simply by polarization modulation.The orientation degeneracy of the classical Malus’s law implies a new degree of freedom and enables us to establish a one-to-many mapping strategy for designing anisotropic plasmonic nanostructures to engineer the Pancharatnam–Berry phase profile,while keeping the continuous intensity modulation unchanged.The proposed Malus metadevice can thus generate a near-field greyscale pattern,and project an independent far-field holographic image using an ultrathin and single-sized metasurface.This concept opens up distinct dimensions for conventional polarization optics,which allows one to merge the functionality of phase manipulation into an amplitudemanipulation-assisted optical component to form a multifunctional nano-optical device without increasing the complexity of the nanostructures.It can empower advanced applications in information multiplexing and encryption,anti-counterfeiting,dual-channel display for virtual/augmented reality,and many other related fields.展开更多
基金Supported by Hunan Provincial Natural Science Foundation of China(Grant No.2021JJ50116).
文摘The service cycle and dynamic performance of structural parts are afected by the weld grinding accuracy and surface consistency. Because of reasons such as assembly errors and thermal deformation, the actual track of the robot does not coincide with the theoretical track when the weld is ground ofine, resulting in poor workpiece surface quality. Considering these problems, in this study, a vision sensing-based online correction system for robotic weld grinding was developed. The system mainly included three subsystems: weld feature extraction, grinding, and robot real-time control. The grinding equipment was frst set as a substation for the robot using the WorkVisual software. The input/output (I/O) ports for communication between the robot and the grinding equipment were confgured via the I/O mapping function to enable the robot to control the grinding equipment (start, stop, and speed control). Subsequently, the Ethernet KRL software package was used to write the data interaction structure to realize realtime communication between the robot and the laser vision system. To correct the measurement error caused by the bending deformation of the workpiece, we established a surface profle model of the base material in the weld area using a polynomial ftting algorithm to compensate for the measurement data. The corrected extracted weld width and height errors were reduced by 2.01% and 9.3%, respectively. Online weld seam extraction and correction experiments verifed the efectiveness of the system’s correction function, and the system could control the grinding trajectory error within 0.2 mm. The reliability of the system was verifed through actual weld grinding experiments. The roughness, Ra, could reach 0.504 µm and the average residual height was within 0.21 mm. In this study, we developed a vision sensing-based online correction system for robotic weld grinding with a good correction efect and high robustness.
基金Supported by the National Natural Science Foundation of China,Research on Energy-saving Mechanism and Dynamic Behavior of Optimizing Trans-wall Heat Transfer Processes of Dividing Wall Columns(21306036)High-level Talent Support Project of Hebei Province,Research on Energy Integration and Process Control of Concentric Internal Thermally Coupled Distillation System(A2017002032)
文摘The energy consumption of distillation operation determines the amount of energy consumption throughout the chemical separation process. A heat integrated distillation column(HIDiC) could greatly reduce the irreversibility of the distillation process, so it gradually becomes a research hotspot. There are two major techniques for heat integration in HIDiC: internally and externally. This review paper describes the major research aspects of an internally heat integrated distillation column(IHIDiC), including the heat transfer models, various design structures(including the two-column HIDiC, Concentric HIDiC, Shell and tube HIDiC, Plate-fin HIDiC and the Super HIDiC, etc.), experimental research, simulation and optimization, process control research, as well as industrial plants and potential industrial applications. Among them, the heat transfer performance of various structures was analyzed of the various design structures based on experimental research, the effects of different factors(including relative volatility, reflux ratio, compression ratio, etc.) on HIDiC energy consumption or TAC is summarized in the simulation part. The calculation methods of the overall heat transfer coefficient and heat transfer models are summarized. The various optimization algorithms and optimization results of simplified HIDiC are summarized in the optimization part. The research status and the key technical issues in various aspects of HIDiC are summarized in this paper. In order to meet the requirements of industrial energy efficiency,the selection of multi-component separation distillation configurations needs to be considered more diversified,and internal complex coupling relationship of HIDiC needs to be further studied.
基金the National Natural Science Foundation of China(Grant Nos.61735010,31671580,and 61601183)Natural Science Foundation of Henan Province,China(Grant No.162300410190)Program for Science&Technology Innovation Talents in Universities of Henan Province,China(Grant No.18HASTIT023)。
文摘We propose a novel scheme for THz wave generation by repeated and continuous frequency conversions from pump wave to high-order Stokes waves(HSWs).The repeated frequency conversions are accomplished by oscillations of Stoke waves in resonant cavity(RC)where low-order Stokes waves(LSWs)are converted to high-order Stokes waves again and again.The continuous frequency conversions are accomplished by optimized cascaded difference frequency generation(OCDFG)where the poling periods of the optical crystal are aperiodic leading to the frequency conversions from low-order Stokes waves to high-order Stokes waves uninterruptedly and unidirectionally.Combined with the repeated and continuous frequency conversions,the optical-to-THz energy conversion efficiency(OTECE)exceeds 26%at 300 K and 43%at 100 K with pump intensities of 300 MW/cm^(2).
基金Project supported by the National Natural Science Foundation of China(Grant No.61601183 and 31671580)the Key Technologies Research and Development Program of Henan Province,China(Grant No.202102210390 and 222102210242)Young Backbone Teachers in University of Henan Province,China(Grant No.2020GGJS099)。
文摘The optical control ability of photonic crystal fiber(PCF)is a distinctive property suitable for improving sensing and plasma performance.This article proposes a dual-core D-channel PCF sensor that can detect two samples simultaneously,which effectively solves the problems of coating difficulty and low wavelength sensitivity.The PCF has four layers of air holes,which dramatically reduces the optical fiber loss and is more conducive to the application of sensors in actual production.In addition,by introducing dual cores on the upper and lower sides of the central air hole,reducing the spacing between the core and the gold nanolayer,a stronger evanescent field can be generated in the cladding air hole.The optical fiber sensor can detect the refractive index of two samples simultaneously with a maximum sensitivity of 21300 nm/RIU.To the best of our knowledge,the sensitivity achieved in this work is the highest sensitivity with the dual sample synchronous detection sensors.The detection range of the refraction index is 1.35-1.41,and the resolution of the sensor is 4.695×10^(-6).Overall,the sensor will be suitable for medical detection,organic chemical sensing,analyte detection,and other fields.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61735010,31671580,and 61601183)the Natural Science Foundation of Henan Province,China(Grant No.162300410190)Program for Science&Technology Innovation Talents in Universities of Henan Province,China(Grant No.18HASTIT023)。
文摘High-efficiency terahertz(THz) wave generation with multiple frequencies by optimized cascaded difference frequency generation(OCDFG) is investigated at 100 K using a nonlinear crystal consisting of a periodically poled lithium niobate(PPLN) part and an aperiodically poled lithium niobate(APPLN) part.Two infrared pump waves with a frequency difference ω_(T1) generate THz waves and a series of cascaded optical waves in the PPLN part by cascaded difference frequency generation(CDFG).The generated cascaded optical waves with frequency interval ω_(T1) then further interact in the APPLN part by OCDFG,yielding the following two advantages.First,OCDFG in the APPLN part is efficiently stimulated by inputting multi-order cascaded optical waves rather than the only two intense infrared pump waves,yielding unprecedented energy conversion efficiencies in excess of 37% at 1 THz at 100 K.Second,THz waves with M timesω_(T1) are generated by mixing the mth-order and the(m+M)th-order cascaded optical waves by designing poling period distributions of the APPLN part.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61735010,31671580,and 61601183)Natural Science Foundation of Henan Province,China(Grant No.162300410190)Program for Science&Technology Innovation Talents in Universities of Henan Province,China(Grant No.18HASTIT023)。
文摘A novel scheme for high-efficiency terahertz(THz)wave generation based on optimized cascaded difference frequency generation(OCDFG)with planar waveguide is presented.The phase mismatches of each-order cascaded difference frequency generation(CDFG)are modulated by changing the thickness of the waveguide,resulting in a decrement of phase mismatches in cascaded Stokes processes and an increment of phase mismatches in cascaded anti-Stokes processes simultaneously.The modulated phase mismatches enhance the cascaded Stokes processes and suppress the cascaded anti-Stokes processes simultaneously,yielding energy conversion efficiencies over 25%from optical wave to THz wave at 100 K.
基金The authors declare no conflict of interest.The authors thank for the financial support from the National Natural Science Foundations of China(No.52071270)the Key Research and Development Program of Shaanxi Province(No.2021GY-232)+2 种基金the Research Fund of the State Key Laboratory of Solidification Processing(NPU)(No.2022-QZ-04)Doctor Dissertation of Northwestern Polytechnical University(No.CX2022029)the National Key Research and Development Program of China(No.2022YFB3808600)。
文摘Metal-organic framework(MOF)-on-MOF structure allows stacking various types of MOFs with different lattice constants for molecule sieving or filtering.However,the multilayered MOFs-based optical devices have incoherent interference due to the lattice-mismatch at the interface and refractive index(RI)indifference.This paper reports isostructural MOFs-based photonic crystals(PCs)designed by stacking Bragg bilayers of lattice-matched MOFs thin films through a layer-by-layer assembly method.Colloidal nanoparticles(NPs)were homogenously encapsulated in some layers of the MOFs(HKUST-1@NPs)to tune their intrinsic RI during the spraying coating process.The isostructural MOFs-based PCs were constructed on a large scale by sequentially spraying coating the low RI layer of HKUST-1 and high RI layer of HKUST-1@NPs to form the desired number of Bragg bilayers.X-ray photoelectron spectroscopy(XPS)depth profiling proved the Bragg bilayers and the homogenous encapsulation of nanomaterials in certain layers of MOFs.Bandwidth of the PCs was tailored by the thickness and RI of the Bragg bilayers,which had a great consistent with finite difference time domain(FDTD)simulation.Importantly,reflectivity of the isostructural MOFs-based PCs was up to 96%.We demonstrated high detection sensitivity for chemical sensing on the PCs,which could be advanced by encapsulating different types of nanomaterials and designing wide-band isostructural MOFs-based PCs.
基金the support from the MOST 2017YFA0205800the funding provided by the National Natural Science Foundation of China(Nos.91950110,11774273,11904267,61805184,and 11674256)+2 种基金the financial support from the Postdoctoral Innovation Talent Support Program of China(BX20180221)the China Postdoctoral Science Foundation(2019M652688)the financial support from the National Research Foundation,Prime Minister’s Office,Singapore under its Competitive Research Program(CRP award NRF CRP15-2015-03).
文摘Polarization optics plays a pivotal role in diffractive,refractive,and emerging flat optics,and has been widely employed in contemporary optical industries and daily life.Advanced polarization manipulation leads to robust control of the polarization direction of light.Nevertheless,polarization control has been studied largely independent of the phase or intensity of light.Here,we propose and experimentally validate a Malus-metasurface-assisted paradigm to enable simultaneous and independent control of the intensity and phase properties of light simply by polarization modulation.The orientation degeneracy of the classical Malus’s law implies a new degree of freedom and enables us to establish a one-to-many mapping strategy for designing anisotropic plasmonic nanostructures to engineer the Pancharatnam–Berry phase profile,while keeping the continuous intensity modulation unchanged.The proposed Malus metadevice can thus generate a near-field greyscale pattern,and project an independent far-field holographic image using an ultrathin and single-sized metasurface.This concept opens up distinct dimensions for conventional polarization optics,which allows one to merge the functionality of phase manipulation into an amplitudemanipulation-assisted optical component to form a multifunctional nano-optical device without increasing the complexity of the nanostructures.It can empower advanced applications in information multiplexing and encryption,anti-counterfeiting,dual-channel display for virtual/augmented reality,and many other related fields.