Thermal diodes,based on the thermal rectification effect,have demonstrated great promise for advanced thermal management.In previous studies,almost all thermal diodes were discussed under the condition of steady state...Thermal diodes,based on the thermal rectification effect,have demonstrated great promise for advanced thermal management.In previous studies,almost all thermal diodes were discussed under the condition of steady states,while the heat source of a practical thermal system often operates under dynamically fluctuating temperatures.Therefore,in this work,we employ finite element simulation to investigate transient thermal rectification behaviors in a well-built heterojunction which exhibits intrinsic thermal rectification effect under steady state.Unidirectional energy transport in the heterojunction system,decoupled from the steady-state temperature bias,is observed under a time-dependent fluctuating heat source.This phenomenon enables straightforward realization of both giant thermal rectification and negative thermal transport.Furthermore,a series of novel thermal regulation strategies are unveiled by adjusting the average temperature,frequency,and phase of the heat source.Our work not only deepens fundamental understanding of thermal regulation in time-dependent oscillating temperature systems but also uncovers many unexplored energy-saving thermal management strategies.展开更多
Enantiomer identification is of paramount industrial value and physiological significance.Construction of sensitive chiral sensors with high enantiomeric discrimination ability is highly desirable.In this work,a chira...Enantiomer identification is of paramount industrial value and physiological significance.Construction of sensitive chiral sensors with high enantiomeric discrimination ability is highly desirable.In this work,a chiral covalent organic framework/anodic aluminum oxide(c-COF/AAO)membrane was prepared for electrochemical enantioselective recognition and sensing.Benefiting from the remarkable asymmetry,the asprepared nanofluidic c-COF/AAO presents a distinct ion current rectification(ICR)characteristic,enabling sensitive bioanalysis.In addition,owing to the large surface area,high chemical stability and perfect ion selectivity of chiral COF,the prepared c-COF/AAO membrane presents exceptionally selective mass transport and thereby enables excellent chiral discrimination for S-/R-Naproxen(S-/R-Npx)enantiomers.It is especially noteworthy that the detection limit is achieved as low as 3.88 pmol/L.These results raise the possibility for a facile,stable and low-cost method to carry out sensitive enantioselective recognition and detection.展开更多
Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectificatio...Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectification performance.To address this issue,we developed a thermal rectification structure comprising a current-biased graphene-coated silicon carbide(SiC)substrate paired with another graphene-coated SiC substrate separated by a nanoscale vacuum gap.A current-biased graphene sheet generates nonreciprocal effect that actively modulates radiative energy transfer.Our theoretical framework demonstrates that the current-biased graphene achieves a high thermal diode efficiency even under a modest temperature difference.Remarkably,the thermal diode efficiency exceeds 0.8 at a temperature difference of just 100 K(between 300 K and 400 K).These findings highlight the synergistic enhancement from graphene coatings and current biasing,providing a viable strategy for nanoscale thermal management applications.展开更多
Carbon nanotubes(CNTs)are widely used in various fields owing to their unique properties.In this study,three different types of nitrogen-doped CNT heterojunctions were constructed:parallel-doped(PCNT),vertically doped...Carbon nanotubes(CNTs)are widely used in various fields owing to their unique properties.In this study,three different types of nitrogen-doped CNT heterojunctions were constructed:parallel-doped(PCNT),vertically doped(VCNT),and mesh-doped(MCNT).Non-equilibrium molecular dynamics(NEMD)simulations were conducted to investigate their heat flux and thermal rectification(TR)effects.The results show that heat flux preferentially flows from nitrogen-doped regions to undoped regions,exhibiting distinct thermal rectification behavior,with PCNT showing the most pronounced effect.Interestingly,the TR ratio of the zigzag PCNT is significantly higher than that of the armchair PCNT.Subsequently,we examined the effects of system length and diameter on the TR ratio of the PCNT and found that the TR ratio increases and then decreases with increasing model length.In addition,the effect of defect density on the heat flux of the PCNT is peculiar.The phonon density of states,phonon dispersion,participation ratio,and phonon spectral heat flux were analyzed to elucidate the thermal transport behavior of phonons in the nanotubes.This study provides insights into the development and design of nitrogen-doped CNT thermal rectifiers.展开更多
The corrosion resistance of Al？Zn？Mg alloy subjected to different times in flame rectification was investigated based on the exfoliation corrosion test. The results indicate that the flame rectification deteriorate...The corrosion resistance of Al？Zn？Mg alloy subjected to different times in flame rectification was investigated based on the exfoliation corrosion test. The results indicate that the flame rectification deteriorates the exfoliation corrosion resistance of Al？Zn？Mg alloy. The corrosion resistance of Al-Zn-Mg alloy is ranked in the following order： base metal〉two times〉three times〉one time of flame rectification. The exfoliation corrosion behavior was discussed based on the transformation of precipitates at grain boundaries and matrix. With increasing the number of times in flame rectification, the precipitate-free zones disappeared and the precipitates experienced dissolution and re-precipitation. The sample was seriously corroded after one time of flame rectification, because the precipitates at grain boundaries are more continuous than those in other samples.展开更多
Nonlinear errors always exist in data obtained from tracker in augmented reality （AR）, which badly influence the effect of AR. This paper proposes to rectify the errors using BP neural network. As BP neural network ...Nonlinear errors always exist in data obtained from tracker in augmented reality （AR）, which badly influence the effect of AR. This paper proposes to rectify the errors using BP neural network. As BP neural network is prone to getting into local extrema and convergence is slow, genetic algorithm is employed to optimize the initial weights and threshold of neural network. This paper discusses how to set the crucial parameters in the algorithm. Experimental results show that the method ensures that the neural network achieves global convergence quickly and correctly. Tracking precision of AR system is improved after the tracker is rectified, and the third dimension of AR system is enhanced.展开更多
By observing two-photon response and anisotropy of the light-induced voltage in Al-Si Schottky barrier potential,it is certified from the experimental and theoretical analysis that the built-in electric field generate...By observing two-photon response and anisotropy of the light-induced voltage in Al-Si Schottky barrier potential,it is certified from the experimental and theoretical analysis that the built-in electric field generated by the Schottky barrier potential will induce the phenomena of optical rectification in Si photodiode.Thus,it is deduced that there must be double-frequency absorption caused by phase-mismatch in the mechanism of two-photon response of Si photodiode.If the intensity of the built-in electric field is strong enough,the double-frequency absorption will be the main factor of the two-photon response,which is different from the conventional opinion that the two-photon response is just the two-photon absorption.展开更多
The finite element method is used to simulate the rectification process of shield machine, to study the relationship between rectification moment and angle and to explore the influence laws of different soil parameter...The finite element method is used to simulate the rectification process of shield machine, to study the relationship between rectification moment and angle and to explore the influence laws of different soil parameters and buried depth on rectification moment. It is hoped that the reference value of rectification moment can be offered to operator, and theoretical foundation can be laid for future automatic rectification technology. The results show that the rectification moment and angle generally exhibit good linear behavior in clay layers with different soil parameters or buried depths, and then the concept of rectification coefficient, that is, the ratio of rectification angle to rectification moment, is proposed; different soil parameters and buried depths have different influences on rectification coefficient, in which elastic modulus has great influence but others have little influences; the simulations of rectification process are preformed in clay layers with different elastic modulus, and fitting results show that elastic modulus and rectification coefficient present the quadratic function relation.展开更多
According to the actual engineering problem that the precise load model of shield machine is difficult to achieve,a design method of sliding mode robust controller oriented to the automatic rectification of shield mac...According to the actual engineering problem that the precise load model of shield machine is difficult to achieve,a design method of sliding mode robust controller oriented to the automatic rectification of shield machine was proposed. Firstly,the nominal load model of shield machine and the ranges of model parameters were obtained by the soil mechanics parameters of certain geological conditions and the messages of the self-learning of shield machine by tunneling for previous segments. Based on this rectification mechanism model with known ranges of parameters,a sliding mode robust controller was proposed. Finally,the simulation analysis was developed to verify the effectiveness of the proposed controller. The simulation results show that the sliding mode robust controller can be implemented in the attitude rectification process of the shield machine and it has stronger robustness to overcome the soil disturbance.展开更多
The polaron effect on the optical rectification in spherical quantum dots with a shallow hydrogenic impurity in the presence of electric field is theoretically investigated by taking into account the interactions of t...The polaron effect on the optical rectification in spherical quantum dots with a shallow hydrogenic impurity in the presence of electric field is theoretically investigated by taking into account the interactions of the electrons with both confined and surface optical phonons. Besides, the interaction between impurity and phonons is also considered. Numerical calculations are presented for typical Zn1-xCdxSe/ZnSe material. It is found that the polaronic effect or electric field leads to the redshifted resonant peaks of the optical rectification coefficients. It is also found that the peak values of the optical rectification coefficients with the polaronic effect are larger than without the polaronic effect, especially for smaller Cd concentrations or stronger electric field.展开更多
The purpose is to explore the effect of the spatial distribution of ground control points （GCPs） on the accuracy of imagery rectification. Both area-distributed and linearly distributed GCPs were used to rectify a L...The purpose is to explore the effect of the spatial distribution of ground control points （GCPs） on the accuracy of imagery rectification. Both area-distributed and linearly distributed GCPs were used to rectify a Landsat TM image of a coastal zone. Rectification accuracy was checked against 99 independent points over the intertidal mudflats with no ground control. Results indicate that the root-mean-square error of residuals over these areas is several times larger than its GCPs-measured counterpart. If the GCPs are spatially dispersed over an area, residuals fluctuate but increase steadily with distance to the source of control in easting （R^2= 0. 827）. in northing they fluctuate around 150 m until 15 km, beyond which they rise steadily at a small range of fluctuation. These residuals are less predictable from distance to the source of control than in easting （R^2= 0.517 ）. If the GCPs are distributed along a control line, residuals rise with distance to it linearly and predictably （R^2 = 0. 877） in the direction perpendicular to it. In a direction parallel to it, the distance has little impact on rectification residuals.展开更多
A new versatile camera calibration technique for machine vision usingoff-the-shelf cameras is described. Aimed at the large distortion of the off-the-shelf cameras, anew camera distortion rectification technology base...A new versatile camera calibration technique for machine vision usingoff-the-shelf cameras is described. Aimed at the large distortion of the off-the-shelf cameras, anew camera distortion rectification technology based on line-rectification is proposed. Afull-camera-distortion model is introduced and a linear algorithm is provided to obtain thesolution. After the camera rectification intrinsic and extrinsic parameters are obtained based onthe relationship between the homograph and absolute conic. This technology needs neither ahigh-accuracy three-dimensional calibration block, nor a complicated translation or rotationplatform. Both simulations and experiments show that this method is effective and robust.展开更多
Mixed integer linear programming （MILP） approach for simultaneous gross error detection and data reconciliation has been proved as an efficient way to adjust process data with material, energy, and other balance con...Mixed integer linear programming （MILP） approach for simultaneous gross error detection and data reconciliation has been proved as an efficient way to adjust process data with material, energy, and other balance constrains. But the efficiency will decrease significantly when this method is applled in a large-scale problem because there are too many binary variables involved. In this article, an improved method is proposed in order to gen- erate gross error candidates with reliability factors before data rectification. Candidates are used in the MILP objec- tive function to improve the efficiency and accuracy by reducing the number of binary variables and giving accurate weights for suspected gross errors candidates. Performance of this improved method is compared and discussed by applying the algorithm in a widely used industrial example.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2023YFA1407001)Department of Science and Technology of Jiangsu Province(Grant No.BK20220032)。
文摘Thermal diodes,based on the thermal rectification effect,have demonstrated great promise for advanced thermal management.In previous studies,almost all thermal diodes were discussed under the condition of steady states,while the heat source of a practical thermal system often operates under dynamically fluctuating temperatures.Therefore,in this work,we employ finite element simulation to investigate transient thermal rectification behaviors in a well-built heterojunction which exhibits intrinsic thermal rectification effect under steady state.Unidirectional energy transport in the heterojunction system,decoupled from the steady-state temperature bias,is observed under a time-dependent fluctuating heat source.This phenomenon enables straightforward realization of both giant thermal rectification and negative thermal transport.Furthermore,a series of novel thermal regulation strategies are unveiled by adjusting the average temperature,frequency,and phase of the heat source.Our work not only deepens fundamental understanding of thermal regulation in time-dependent oscillating temperature systems but also uncovers many unexplored energy-saving thermal management strategies.
基金supported by grants from the National Natural Science Foundation of China(Nos.22274076,22304084)the Primary Research&Development Plan of Jiangsu Province(No.BE2022793)+1 种基金the Natural Science Foundation of Jiangsu Province of China(No.BK20230377)Jiangsu Provincial Department of Education(No.211090B52303)。
文摘Enantiomer identification is of paramount industrial value and physiological significance.Construction of sensitive chiral sensors with high enantiomeric discrimination ability is highly desirable.In this work,a chiral covalent organic framework/anodic aluminum oxide(c-COF/AAO)membrane was prepared for electrochemical enantioselective recognition and sensing.Benefiting from the remarkable asymmetry,the asprepared nanofluidic c-COF/AAO presents a distinct ion current rectification(ICR)characteristic,enabling sensitive bioanalysis.In addition,owing to the large surface area,high chemical stability and perfect ion selectivity of chiral COF,the prepared c-COF/AAO membrane presents exceptionally selective mass transport and thereby enables excellent chiral discrimination for S-/R-Naproxen(S-/R-Npx)enantiomers.It is especially noteworthy that the detection limit is achieved as low as 3.88 pmol/L.These results raise the possibility for a facile,stable and low-cost method to carry out sensitive enantioselective recognition and detection.
基金Project supported by the National Natural Science Foundation of China(Grant No.12364008)the Ph.D.Research Startup Foundation of Yan’an University(Grant No.YDBK2019-54)the Yan’an High-level Talent Special Project(Grant No.2019263166)。
文摘Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectification performance.To address this issue,we developed a thermal rectification structure comprising a current-biased graphene-coated silicon carbide(SiC)substrate paired with another graphene-coated SiC substrate separated by a nanoscale vacuum gap.A current-biased graphene sheet generates nonreciprocal effect that actively modulates radiative energy transfer.Our theoretical framework demonstrates that the current-biased graphene achieves a high thermal diode efficiency even under a modest temperature difference.Remarkably,the thermal diode efficiency exceeds 0.8 at a temperature difference of just 100 K(between 300 K and 400 K).These findings highlight the synergistic enhancement from graphene coatings and current biasing,providing a viable strategy for nanoscale thermal management applications.
基金supported by the National Natural Science Foundation of China(Grant No.52476071)the Natural Science Foundation of Hebei Province(Grant No.A2024502008).
文摘Carbon nanotubes(CNTs)are widely used in various fields owing to their unique properties.In this study,three different types of nitrogen-doped CNT heterojunctions were constructed:parallel-doped(PCNT),vertically doped(VCNT),and mesh-doped(MCNT).Non-equilibrium molecular dynamics(NEMD)simulations were conducted to investigate their heat flux and thermal rectification(TR)effects.The results show that heat flux preferentially flows from nitrogen-doped regions to undoped regions,exhibiting distinct thermal rectification behavior,with PCNT showing the most pronounced effect.Interestingly,the TR ratio of the zigzag PCNT is significantly higher than that of the armchair PCNT.Subsequently,we examined the effects of system length and diameter on the TR ratio of the PCNT and found that the TR ratio increases and then decreases with increasing model length.In addition,the effect of defect density on the heat flux of the PCNT is peculiar.The phonon density of states,phonon dispersion,participation ratio,and phonon spectral heat flux were analyzed to elucidate the thermal transport behavior of phonons in the nanotubes.This study provides insights into the development and design of nitrogen-doped CNT thermal rectifiers.
基金Projects(51374048,50904012)supported by the National Natural Science Foundation of China
文摘The corrosion resistance of Al？Zn？Mg alloy subjected to different times in flame rectification was investigated based on the exfoliation corrosion test. The results indicate that the flame rectification deteriorates the exfoliation corrosion resistance of Al？Zn？Mg alloy. The corrosion resistance of Al-Zn-Mg alloy is ranked in the following order： base metal〉two times〉three times〉one time of flame rectification. The exfoliation corrosion behavior was discussed based on the transformation of precipitates at grain boundaries and matrix. With increasing the number of times in flame rectification, the precipitate-free zones disappeared and the precipitates experienced dissolution and re-precipitation. The sample was seriously corroded after one time of flame rectification, because the precipitates at grain boundaries are more continuous than those in other samples.
基金Project supported by Science Foundation of Shanghai Municipal Commission of Science and Technology (Grant No .025115008)
文摘Nonlinear errors always exist in data obtained from tracker in augmented reality （AR）, which badly influence the effect of AR. This paper proposes to rectify the errors using BP neural network. As BP neural network is prone to getting into local extrema and convergence is slow, genetic algorithm is employed to optimize the initial weights and threshold of neural network. This paper discusses how to set the crucial parameters in the algorithm. Experimental results show that the method ensures that the neural network achieves global convergence quickly and correctly. Tracking precision of AR system is improved after the tracker is rectified, and the third dimension of AR system is enhanced.
文摘By observing two-photon response and anisotropy of the light-induced voltage in Al-Si Schottky barrier potential,it is certified from the experimental and theoretical analysis that the built-in electric field generated by the Schottky barrier potential will induce the phenomena of optical rectification in Si photodiode.Thus,it is deduced that there must be double-frequency absorption caused by phase-mismatch in the mechanism of two-photon response of Si photodiode.If the intensity of the built-in electric field is strong enough,the double-frequency absorption will be the main factor of the two-photon response,which is different from the conventional opinion that the two-photon response is just the two-photon absorption.
基金Project(2007CB714006)supported by the National Basic Research Program of China
文摘The finite element method is used to simulate the rectification process of shield machine, to study the relationship between rectification moment and angle and to explore the influence laws of different soil parameters and buried depth on rectification moment. It is hoped that the reference value of rectification moment can be offered to operator, and theoretical foundation can be laid for future automatic rectification technology. The results show that the rectification moment and angle generally exhibit good linear behavior in clay layers with different soil parameters or buried depths, and then the concept of rectification coefficient, that is, the ratio of rectification angle to rectification moment, is proposed; different soil parameters and buried depths have different influences on rectification coefficient, in which elastic modulus has great influence but others have little influences; the simulations of rectification process are preformed in clay layers with different elastic modulus, and fitting results show that elastic modulus and rectification coefficient present the quadratic function relation.
基金Project(2007CB714006) supported by the National Basic Research Program of China
文摘According to the actual engineering problem that the precise load model of shield machine is difficult to achieve,a design method of sliding mode robust controller oriented to the automatic rectification of shield machine was proposed. Firstly,the nominal load model of shield machine and the ranges of model parameters were obtained by the soil mechanics parameters of certain geological conditions and the messages of the self-learning of shield machine by tunneling for previous segments. Based on this rectification mechanism model with known ranges of parameters,a sliding mode robust controller was proposed. Finally,the simulation analysis was developed to verify the effectiveness of the proposed controller. The simulation results show that the sliding mode robust controller can be implemented in the attitude rectification process of the shield machine and it has stronger robustness to overcome the soil disturbance.
基金supported by the National Natural Science Foundation of China(Grant No.11364028)the Major Projects of the Natural Science Foundation of Inner Mongolia Autonomous Region,China(Grant No.2013ZD02)the Project of "Prairie Excellent" Engineering in Inner Mongolia Autonomous Region,China
文摘The polaron effect on the optical rectification in spherical quantum dots with a shallow hydrogenic impurity in the presence of electric field is theoretically investigated by taking into account the interactions of the electrons with both confined and surface optical phonons. Besides, the interaction between impurity and phonons is also considered. Numerical calculations are presented for typical Zn1-xCdxSe/ZnSe material. It is found that the polaronic effect or electric field leads to the redshifted resonant peaks of the optical rectification coefficients. It is also found that the peak values of the optical rectification coefficients with the polaronic effect are larger than without the polaronic effect, especially for smaller Cd concentrations or stronger electric field.
基金financially supported by a grant from the joint key project of National Natural Science Foundation of China under contract(No.50339010)the National"211"Key Project of China.
文摘The purpose is to explore the effect of the spatial distribution of ground control points （GCPs） on the accuracy of imagery rectification. Both area-distributed and linearly distributed GCPs were used to rectify a Landsat TM image of a coastal zone. Rectification accuracy was checked against 99 independent points over the intertidal mudflats with no ground control. Results indicate that the root-mean-square error of residuals over these areas is several times larger than its GCPs-measured counterpart. If the GCPs are spatially dispersed over an area, residuals fluctuate but increase steadily with distance to the source of control in easting （R^2= 0. 827）. in northing they fluctuate around 150 m until 15 km, beyond which they rise steadily at a small range of fluctuation. These residuals are less predictable from distance to the source of control than in easting （R^2= 0.517 ）. If the GCPs are distributed along a control line, residuals rise with distance to it linearly and predictably （R^2 = 0. 877） in the direction perpendicular to it. In a direction parallel to it, the distance has little impact on rectification residuals.
文摘A new versatile camera calibration technique for machine vision usingoff-the-shelf cameras is described. Aimed at the large distortion of the off-the-shelf cameras, anew camera distortion rectification technology based on line-rectification is proposed. Afull-camera-distortion model is introduced and a linear algorithm is provided to obtain thesolution. After the camera rectification intrinsic and extrinsic parameters are obtained based onthe relationship between the homograph and absolute conic. This technology needs neither ahigh-accuracy three-dimensional calibration block, nor a complicated translation or rotationplatform. Both simulations and experiments show that this method is effective and robust.
基金Supported by the National High Technology Research and Development Program of China (2007AA40702 and 2007AA04Z191)
文摘Mixed integer linear programming （MILP） approach for simultaneous gross error detection and data reconciliation has been proved as an efficient way to adjust process data with material, energy, and other balance constrains. But the efficiency will decrease significantly when this method is applled in a large-scale problem because there are too many binary variables involved. In this article, an improved method is proposed in order to gen- erate gross error candidates with reliability factors before data rectification. Candidates are used in the MILP objec- tive function to improve the efficiency and accuracy by reducing the number of binary variables and giving accurate weights for suspected gross errors candidates. Performance of this improved method is compared and discussed by applying the algorithm in a widely used industrial example.
