Morphing unmanned aerial vehicle(UAV) can manipulate its shape for excellent flight performance under different conditions.The most research of the morphing UAV focuses on modeling. However, the issues including nonli...Morphing unmanned aerial vehicle(UAV) can manipulate its shape for excellent flight performance under different conditions.The most research of the morphing UAV focuses on modeling. However, the issues including nonlinear characteristics, strong couplings, and mismatched disturbances are inevitable, which can lead to a great challenge in controller design. In this paper,a composite anti-disturbance controller is developed for morphing UAV to achieve enhanced flight performance under multiple sources of disturbances. In the inner loop, a nonlinear disturbance observer(DO) is constructed to estimate the inertial forces and moment;while in the outer loop, the command filtered backstepping(CFBS) method is adopted to guarantee the stability of the closed-loop system. The system outputs can promptly track reference signals in the morphing process of the UAV. The novelty is that the disturbance estimations are added into the control laws to compensate the mismatched disturbances. When comparing to the previous methods, the control scheme presented in this study can significantly improve the performance of anti-disturbance.Finally, the effectiveness of the proposed method is illustrated by numerical simulations.展开更多
Surface-enhanced Raman scattering（SERS） is applied to detect the concentration of carbendzim（CBZ） in tea leaves. Au colloid is selected and used for active surfaces, and the extraction conditions are optimized in ...Surface-enhanced Raman scattering（SERS） is applied to detect the concentration of carbendzim（CBZ） in tea leaves. Au colloid is selected and used for active surfaces, and the extraction conditions are optimized in the experiment. The linearity range for the SERS intensity and the concentration of CBZ is found to be0.5 to 8 mg kgà1. The detection limit for CBZ is 0.1 mg kgà1and its recovery in tea samples is 72.3%. The detection results for CBZ using this method are compared with those of HPLC, and no obvious difference can be found. In addition, by dripping the condensed Au colloid on the tea leaves, the proposed SERS approach could be used to the in-situ determination of the half life period of CBZ on tea leaves.展开更多
Thermally expanded graphite was functionalized with 4-bromophenyl addends using the in situ diazonium formation procedure,and after mild sonication treatment in N,N’-dimethylformamide,thin graphene layers were exfoli...Thermally expanded graphite was functionalized with 4-bromophenyl addends using the in situ diazonium formation procedure,and after mild sonication treatment in N,N’-dimethylformamide,thin graphene layers were exfoliated from the bulk graphite.These chemically-assisted exfoliated graphene(CEG)sheets had higher solubility than pristine graphene without any stabilizer additive.More than 70%of these soluble flakes had less than 5 layers.Energy filtered transmission electron microscopy(EFTEM)elemental mapping provided evidence of the edge-selective diazonium functionalization with graphene.A majority of the Br signals came from the edges of the CEG indicating that the basal planes were not highly functionalized.The CEG was also characterized by X-ray photoelectron spectroscopy,atomic force microscopy,Raman spectroscopy,and transmission electron microscopy.展开更多
Recently,Cooperative Spectrum Sensing(CSS)for Cognitive Radio Networks(CRN)plays a significant role in efficient 5G wireless communication.Spectrum sensing is a significant technology in CRN to identify underutilized ...Recently,Cooperative Spectrum Sensing(CSS)for Cognitive Radio Networks(CRN)plays a significant role in efficient 5G wireless communication.Spectrum sensing is a significant technology in CRN to identify underutilized spectrums.The CSS technique is highly applicable due to its fast and efficient performance.5G wireless communication is widely employed for the continuous development of efficient and accurate Internet of Things(IoT)networks.5G wireless communication will potentially lead the way for next generation IoT communication.CSS has established significant consideration as a feasible resource to improve identification performance by developing spatial diversity in receiving signal strength in IoT.In this paper,an optimal CSS for CRN is performed using Offset Quadrature Amplitude Modulation Universal Filtered Multi-Carrier Non-Orthogonal Multiple Access(OQAM/UFMC/NOMA)methodologies.Availability of spectrum and bandwidth utilization is a key challenge in CRN for IoT 5G wireless communication.The optimal solution for CRN in IoT-based 5G communication should be able to provide optimal bandwidth and CSS,low latency,Signal Noise Ratio(SNR)improvement,maximum capacity,offset synchronization,and Peak Average Power Ratio(PAPR)reduction.The Energy Efficient All-Pass Filter(EEAPF)algorithm is used to eliminate PAPR.The deployment approach improves Quality of Service(QoS)in terms of system reliability,throughput,and energy efficiency.Our in-depth experimental results show that the proposed methodology provides an optimal solution when directly compares against current existing methodologies.展开更多
In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated...In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV constraint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive controller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the command filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.展开更多
At the 2024 China International Fair for Trade in Services(CIFTIS),Lu Xiaodong,a staff member working at the booth of mobile payment platform Alipay,addressed a screen in front of a small crowd of visitors."I'...At the 2024 China International Fair for Trade in Services(CIFTIS),Lu Xiaodong,a staff member working at the booth of mobile payment platform Alipay,addressed a screen in front of a small crowd of visitors."I'm looking for a job as a waiter,"he said.Instantly,a list of relevant job openings appeared on the screen."Please show me positions with a salary above 4,000 yuan($564),"he continued,and the job listings were immediately filtered.He selected one position and inquired further about the job's location and working conditions,all of which were answered by the digital assistant Xiao Gu.展开更多
An interference suppression design scheme based on conjugate weighted butterfly interleaving mapping(CWBIM)is proposed for inter-carrier interference(ICI)and inter-subband interference(IBI)in the received signals of u...An interference suppression design scheme based on conjugate weighted butterfly interleaving mapping(CWBIM)is proposed for inter-carrier interference(ICI)and inter-subband interference(IBI)in the received signals of universal filtered multi-carrier(UFMC)systems.It applies an interleaving mapping operation to subtract the interference coefficients of adjacent terms in ICI and IBI twice,thereby achieving suppression effects similar to the self-cancellation(SC)algorithm while maintaining the original data transmission efficiency.Meanwhile,conjugate and complex weighting operations can effectively suppress the impact of phase rotation errors in high-speed mobile channel environments,thereby further improving the bit error rate(BFR)performance of the system,Moreover,butterfly operation can effectively control the computational complexity of the interleaving mapping process.Theoretical analysis and simulation results show that,compared with the PSC-UFMC algorithm,the CWBIM-UFMC scheme proposed in this paper can effectively suppress ICI and IBI in the received signal without compromising data transmission efficiency and reducing computational complexity,thereby achieving good BER performance of the system.展开更多
A filtered density function (FDF) transport equation was derived for the fluid velocity seen by the particles in gas-particle two-phase flow. An LES/FDF simulation of a two-phase plane wake flow was carried out. The s...A filtered density function (FDF) transport equation was derived for the fluid velocity seen by the particles in gas-particle two-phase flow. An LES/FDF simulation of a two-phase plane wake flow was carried out. The simulation results were compared with both the experimental photograph and the simulation results without using the FDF model, and proved that the LES/FDF model can clearly improve the spatial dispersion of the particle phase.展开更多
The present study extracts human-understandable insights from machine learning(ML)-based mesoscale closure in fluid-particle flows via several novel data-driven analysis approaches,i.e.,maximal information coefficient...The present study extracts human-understandable insights from machine learning(ML)-based mesoscale closure in fluid-particle flows via several novel data-driven analysis approaches,i.e.,maximal information coefficient(MIC),interpretable ML,and automated ML.It is previously shown that the solidvolume fraction has the greatest effect on the drag force.The present study aims to quantitativelyinvestigate the influence of flow properties on mesoscale drag correction(H_(d)).The MIC results showstrong correlations between the features(i.e.,slip velocity(u^(*)_(sy))and particle volume fraction(εs))and thelabel H_(d).The interpretable ML analysis confirms this conclusion,and quantifies the contribution of u^(*)_(sy),εs and gas pressure gradient to the model as 71.9%,27.2%and 0.9%,respectively.Automated ML without theneed to select the model structure and hyperparameters is used for modeling,improving the predictionaccuracy over our previous model(Zhu et al.,2020;Ouyang,Zhu,Su,&Luo,2021).展开更多
The difficulty in solving stochastic dynamics problems lies in the need for a large number of repeated computations of deterministic dynamic equations,which has been a challenge in stochastic dynamics analysis and was...The difficulty in solving stochastic dynamics problems lies in the need for a large number of repeated computations of deterministic dynamic equations,which has been a challenge in stochastic dynamics analysis and was discussed in this study.To efficiently and accurately compute the exponential of the dynamics state matrix and the matrix functions due to external loads,an adaptively filtered precise integration method was proposed,which inherits the high precision of the precise integrationmethod,improves the computational efficiency and saves the memory required.Moreover,the perturbation method was introduced to avoid repeated computations of matrix exponential and terms due to external loads.Based on the filtering and perturbation techniques,an adaptively filtered precise integration method considering perturbation for stochastic dynamics problems was developed.Two numerical experiments,including a model of phononic crystal and a bridge model considering random parameters,were performed to test the performance of the proposed method in terms of accuracy and efficiency.Numerical results show that the accuracy and efficiency of the proposed method are better than those of the existing precise integration method,the Newmark-βmethod and the Wilson-θmethod.展开更多
Energy resolution is affected by the intrinsic energy resolution of the detector, ballistic deficit, pileup pulses and noise. Pile-up pulses become the dominant factor that degrades energy resolution after the system ...Energy resolution is affected by the intrinsic energy resolution of the detector, ballistic deficit, pileup pulses and noise. Pile-up pulses become the dominant factor that degrades energy resolution after the system is established, so pile-up rejection is often applied to obtain good energy resolution by discarding pulses that are expected to be contaminated by pile-up. However, pile-up rejection can reduce count rates and thus lower the measurement precision. In order to improve count rates and maintain energy resolution, a new method of pile-up pulse identification based on trapezoidal pulse shaping is presented. Combined with pulse width discrimination, this method is implemented by recording pulses that are not seriously piled up. Some experimental tests with a Cu-Pb alloy sample are carried out to verify the performance of this method in X-ray spectrometry. The results show that the method can significantly improve count rates without degrading energy resolution.展开更多
TiAIN]Cu nanocomposite coatings with Cu concentration of 0-1.4 at.% were deposited on the high- speed steel （HSS） substrates by filtered cathodic arc ion plating technique. The chemical composition, microstructure, ...TiAIN]Cu nanocomposite coatings with Cu concentration of 0-1.4 at.% were deposited on the high- speed steel （HSS） substrates by filtered cathodic arc ion plating technique. The chemical composition, microstructure, morphology, adhesion strength, mechanical and tribological properties of the TiAIN/Cu coatings were characterized and analyzed. The results reveal that the coating structure and properties depend on not only the Cu concentration, hut also the deposition condition. The addition of Cu significantly decreases the grain size and weakens the texture in the TiAlN/Cu coatings. With increasing the Cu concentration, the coating hardness decreases slightly from 30.7 GPa of the pure TiAlN coating to 28.5 GPa of the TiAlN/Cu coating with 1.4 at,% Cu. All the TiAlN/Cu coatings present sufficient adhesion strength. In addition, the existing state of additive Cu in the TiAlN/Cu coatings is also investigated.展开更多
An LES/FDF model was developed by the authors to investigate the SGS effect on the particle motion in the gas-particle two-phase plane wake flow.The simulation results of dispersion rate for different particles were c...An LES/FDF model was developed by the authors to investigate the SGS effect on the particle motion in the gas-particle two-phase plane wake flow.The simulation results of dispersion rate for different particles were compared with the results without using the FDF model.It was shown that the large eddy structure is the dominant factor influencing the particle diffu-sion in space for small particles(small Stokes-number particles),but for intermediate or large diameter particles,the influence of the sub-grid scale eddies on the dispersion rate is in the same order as that of the large eddies.The sub-grid scale eddies increase the particle dispersion rate in most time,but sometimes they decrease the dispersion rate.The sub-grid scale particle dispersion rate is decided not only by the intensity of sub-grid scale eddies and the Stokes number of the particles,but also by the large eddy structure of the flow field.For the particles in isotropic turbulence,the dispersion rate decreases as the particle diameter increases.展开更多
In this paper we show that if R is a discrete valuation ring, then R is a filtered ring. We prove some properties and relation when R is a discrete valuation ring.
Let R be a filtered Noetherian ring with identity and M an R-filtered module. The associated graded ring of R is denoted by G(R) and the associated graded G(R) module of M is denoted by gr(M). Bjork studied in ref. [1...Let R be a filtered Noetherian ring with identity and M an R-filtered module. The associated graded ring of R is denoted by G(R) and the associated graded G(R) module of M is denoted by gr(M). Bjork studied in ref. [1] the relation between M being a module with a good filtration and gr(M) being a finitely generated module. If R is a ring with positive filtration and G(R) is a Noetherian ring, then M is a module with good filtration if and only if gr(M) is a finitely generated G(R) module. But when R is a Zariski filtered ring,we do not know if the conclusion is true. To be specific, Bjork’s problem is:展开更多
Achieving passive microparticle filtration with micropore membranes is challenging due to the capillary pinning effect of the membranes.Inspired by the teapot effect that occurs when liquid(tea)is poured from a teapot...Achieving passive microparticle filtration with micropore membranes is challenging due to the capillary pinning effect of the membranes.Inspired by the teapot effect that occurs when liquid(tea)is poured from a teapot spout,we proposed a tap-triggered self-wetting strategy and utilized the method with a 3D sieve to flter rare cells.First,a 3D-printed polymer tap-trigger microstructure was implemented.As a result,the 3μm micropore membrane gating threshold(the pressure needed to open the micropores)was lowered from above 3000 to 80 Pa by the tap-trigger microstructure that facilated the liquid leakage and spreading to self-wet more membrane area in a positive feedback loop.Then,we implemented a 3D cone-shaped cell sieve with tap-trigger microstructures.Driven by gravity,the sieve performed at a high throughput above 20 mL/min(DPBS),while the micropore size and porosity were 3μm and 14.1%,respectively.We further filtered leukocytes from whole blood samples with the proposed new 3D sieve,and the method was compared with the traditional method of leukocyte isolation by chemically removing red blood cells.The device exhibited comparable leukocyte purity but a higher platelet removal rate and lower leukocyte simulation level,facilitating downstream single-cell analysis.The key results indicated that the tap-triggered self-wetting strategy could significantly improve the performance of passive microparticle filtration.展开更多
For the crystalline temperature of BaSnO_(3)(BTO)was above 650℃,the transparent conductive BTO-based films were always deposited above this temperature on epitaxy substrates by pulsed laser deposition or molecular be...For the crystalline temperature of BaSnO_(3)(BTO)was above 650℃,the transparent conductive BTO-based films were always deposited above this temperature on epitaxy substrates by pulsed laser deposition or molecular beam epitaxy till now which limited there application in low temperature device process.In the article,the microstructure,optical and electrical of BTO and In_(2)O_(3) mixed transparent conductive BaInSnO_(x)(BITO)film deposited by filtered cathodic vacuum arc technique(FCVA)on glass substrate at room temperature were firstly reported.The BITO film with thickness of 300 nm had mainly In_(2)O_(3) polycrystalline phase,and minor polycrystalline BTO phase with(001),(011),(111),(002),(222)crystal faces which were first deposited at room temperature on amorphous glass.The transmittance was 70%–80%in the visible light region with linear refractive index of 1.94 and extinction coefficient of 0.004 at 550-nm wavelength.The basic optical properties included the real and imaginary parts,high frequency dielectric constants,the absorption coefficient,the Urbach energy,the indirect and direct band gaps,the oscillator and dispersion energies,the static refractive index and dielectric constant,the average oscillator wavelength,oscillator length strength,the linear and the third-order nonlinear optical susceptibilities,and the nonlinear refractive index were all calculated.The film was the n-type conductor with sheet resistance of 704.7Ω/□,resistivity of 0.02Ω⋅cm,mobility of 18.9 cm2/V⋅s,and carrier electron concentration of 1.6×10^(19) cm^(−3) at room temperature.The results suggested that the BITO film deposited by FCVA had potential application in transparent conductive films-based low temperature device process.展开更多
文摘Morphing unmanned aerial vehicle(UAV) can manipulate its shape for excellent flight performance under different conditions.The most research of the morphing UAV focuses on modeling. However, the issues including nonlinear characteristics, strong couplings, and mismatched disturbances are inevitable, which can lead to a great challenge in controller design. In this paper,a composite anti-disturbance controller is developed for morphing UAV to achieve enhanced flight performance under multiple sources of disturbances. In the inner loop, a nonlinear disturbance observer(DO) is constructed to estimate the inertial forces and moment;while in the outer loop, the command filtered backstepping(CFBS) method is adopted to guarantee the stability of the closed-loop system. The system outputs can promptly track reference signals in the morphing process of the UAV. The novelty is that the disturbance estimations are added into the control laws to compensate the mismatched disturbances. When comparing to the previous methods, the control scheme presented in this study can significantly improve the performance of anti-disturbance.Finally, the effectiveness of the proposed method is illustrated by numerical simulations.
基金financially supported by the National Instrumentation Program(NO.2011YQ0301240904)
文摘Surface-enhanced Raman scattering（SERS） is applied to detect the concentration of carbendzim（CBZ） in tea leaves. Au colloid is selected and used for active surfaces, and the extraction conditions are optimized in the experiment. The linearity range for the SERS intensity and the concentration of CBZ is found to be0.5 to 8 mg kgà1. The detection limit for CBZ is 0.1 mg kgà1and its recovery in tea samples is 72.3%. The detection results for CBZ using this method are compared with those of HPLC, and no obvious difference can be found. In addition, by dripping the condensed Au colloid on the tea leaves, the proposed SERS approach could be used to the in-situ determination of the half life period of CBZ on tea leaves.
基金We thank the U.S.Department of Energy's Office of Energy Efficiency and Renewable Energy within the Hydrogen Sorption Center of Excellence,No.DE-FC-36-05GO15073,the Air Force Office of Scientific Research(CONTACT),the Office of Naval Research through a Multidisciplinary University Research Initiative(MURI)with the University of California,Berkeley(00006766)and the Advanced Energy Consortium(member companies include BP America Inc.,Baker Hughes Inc.,Conoco-Phillips,Halliburton Energy Services Inc.,Marathon Oil Corp.,Occidental Oil and Gas,Petrobras,Schlumberger,Shell,and Total)for financial support.Thanks to Dr.Wenhua Guo for assistance with the TEM.
文摘Thermally expanded graphite was functionalized with 4-bromophenyl addends using the in situ diazonium formation procedure,and after mild sonication treatment in N,N’-dimethylformamide,thin graphene layers were exfoliated from the bulk graphite.These chemically-assisted exfoliated graphene(CEG)sheets had higher solubility than pristine graphene without any stabilizer additive.More than 70%of these soluble flakes had less than 5 layers.Energy filtered transmission electron microscopy(EFTEM)elemental mapping provided evidence of the edge-selective diazonium functionalization with graphene.A majority of the Br signals came from the edges of the CEG indicating that the basal planes were not highly functionalized.The CEG was also characterized by X-ray photoelectron spectroscopy,atomic force microscopy,Raman spectroscopy,and transmission electron microscopy.
文摘Recently,Cooperative Spectrum Sensing(CSS)for Cognitive Radio Networks(CRN)plays a significant role in efficient 5G wireless communication.Spectrum sensing is a significant technology in CRN to identify underutilized spectrums.The CSS technique is highly applicable due to its fast and efficient performance.5G wireless communication is widely employed for the continuous development of efficient and accurate Internet of Things(IoT)networks.5G wireless communication will potentially lead the way for next generation IoT communication.CSS has established significant consideration as a feasible resource to improve identification performance by developing spatial diversity in receiving signal strength in IoT.In this paper,an optimal CSS for CRN is performed using Offset Quadrature Amplitude Modulation Universal Filtered Multi-Carrier Non-Orthogonal Multiple Access(OQAM/UFMC/NOMA)methodologies.Availability of spectrum and bandwidth utilization is a key challenge in CRN for IoT 5G wireless communication.The optimal solution for CRN in IoT-based 5G communication should be able to provide optimal bandwidth and CSS,low latency,Signal Noise Ratio(SNR)improvement,maximum capacity,offset synchronization,and Peak Average Power Ratio(PAPR)reduction.The Energy Efficient All-Pass Filter(EEAPF)algorithm is used to eliminate PAPR.The deployment approach improves Quality of Service(QoS)in terms of system reliability,throughput,and energy efficiency.Our in-depth experimental results show that the proposed methodology provides an optimal solution when directly compares against current existing methodologies.
文摘In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV constraint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive controller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the command filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.
文摘At the 2024 China International Fair for Trade in Services(CIFTIS),Lu Xiaodong,a staff member working at the booth of mobile payment platform Alipay,addressed a screen in front of a small crowd of visitors."I'm looking for a job as a waiter,"he said.Instantly,a list of relevant job openings appeared on the screen."Please show me positions with a salary above 4,000 yuan($564),"he continued,and the job listings were immediately filtered.He selected one position and inquired further about the job's location and working conditions,all of which were answered by the digital assistant Xiao Gu.
基金Supported by the National Natural Science Foundation of China(No.61601296,61701295)the Science and Technology Innovation ActionPlan Project of Shanghai Science and Technology Commission(No.20511103500)the Talent Program of Shanghai University of Engineer-ing Science(No.2018RC43)。
文摘An interference suppression design scheme based on conjugate weighted butterfly interleaving mapping(CWBIM)is proposed for inter-carrier interference(ICI)and inter-subband interference(IBI)in the received signals of universal filtered multi-carrier(UFMC)systems.It applies an interleaving mapping operation to subtract the interference coefficients of adjacent terms in ICI and IBI twice,thereby achieving suppression effects similar to the self-cancellation(SC)algorithm while maintaining the original data transmission efficiency.Meanwhile,conjugate and complex weighting operations can effectively suppress the impact of phase rotation errors in high-speed mobile channel environments,thereby further improving the bit error rate(BFR)performance of the system,Moreover,butterfly operation can effectively control the computational complexity of the interleaving mapping process.Theoretical analysis and simulation results show that,compared with the PSC-UFMC algorithm,the CWBIM-UFMC scheme proposed in this paper can effectively suppress ICI and IBI in the received signal without compromising data transmission efficiency and reducing computational complexity,thereby achieving good BER performance of the system.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10502044, 10772162, 50736006)
文摘A filtered density function (FDF) transport equation was derived for the fluid velocity seen by the particles in gas-particle two-phase flow. An LES/FDF simulation of a two-phase plane wake flow was carried out. The simulation results were compared with both the experimental photograph and the simulation results without using the FDF model, and proved that the LES/FDF model can clearly improve the spatial dispersion of the particle phase.
基金This work was supported by the National Natural ScienceFoundation of China(No.U1862201,91834303 and 22208208)the China Postdoctoral Science Foundation(No.2022M712056)the China National Postdoctoral Program for Innovative Talents(No.BX20220205).
文摘The present study extracts human-understandable insights from machine learning(ML)-based mesoscale closure in fluid-particle flows via several novel data-driven analysis approaches,i.e.,maximal information coefficient(MIC),interpretable ML,and automated ML.It is previously shown that the solidvolume fraction has the greatest effect on the drag force.The present study aims to quantitativelyinvestigate the influence of flow properties on mesoscale drag correction(H_(d)).The MIC results showstrong correlations between the features(i.e.,slip velocity(u^(*)_(sy))and particle volume fraction(εs))and thelabel H_(d).The interpretable ML analysis confirms this conclusion,and quantifies the contribution of u^(*)_(sy),εs and gas pressure gradient to the model as 71.9%,27.2%and 0.9%,respectively.Automated ML without theneed to select the model structure and hyperparameters is used for modeling,improving the predictionaccuracy over our previous model(Zhu et al.,2020;Ouyang,Zhu,Su,&Luo,2021).
基金the support of the National Natural Science Foundation of China(Grant Nos.11472067 and 51609034)the Science Foundation of Liaoning Province of China(No.2021-MS-119)+1 种基金the Dalian Youth Science and Technology Star Project(No.2018RQ06)the Fundamental Research Funds for the Central Universities(Grant No.DUT20GJ216).
文摘The difficulty in solving stochastic dynamics problems lies in the need for a large number of repeated computations of deterministic dynamic equations,which has been a challenge in stochastic dynamics analysis and was discussed in this study.To efficiently and accurately compute the exponential of the dynamics state matrix and the matrix functions due to external loads,an adaptively filtered precise integration method was proposed,which inherits the high precision of the precise integrationmethod,improves the computational efficiency and saves the memory required.Moreover,the perturbation method was introduced to avoid repeated computations of matrix exponential and terms due to external loads.Based on the filtering and perturbation techniques,an adaptively filtered precise integration method considering perturbation for stochastic dynamics problems was developed.Two numerical experiments,including a model of phononic crystal and a bridge model considering random parameters,were performed to test the performance of the proposed method in terms of accuracy and efficiency.Numerical results show that the accuracy and efficiency of the proposed method are better than those of the existing precise integration method,the Newmark-βmethod and the Wilson-θmethod.
基金Supported by National Natural Science Foundation of China(11475036,41404108)
文摘Energy resolution is affected by the intrinsic energy resolution of the detector, ballistic deficit, pileup pulses and noise. Pile-up pulses become the dominant factor that degrades energy resolution after the system is established, so pile-up rejection is often applied to obtain good energy resolution by discarding pulses that are expected to be contaminated by pile-up. However, pile-up rejection can reduce count rates and thus lower the measurement precision. In order to improve count rates and maintain energy resolution, a new method of pile-up pulse identification based on trapezoidal pulse shaping is presented. Combined with pulse width discrimination, this method is implemented by recording pulses that are not seriously piled up. Some experimental tests with a Cu-Pb alloy sample are carried out to verify the performance of this method in X-ray spectrometry. The results show that the method can significantly improve count rates without degrading energy resolution.
基金supported by the National Key Basic Research Program of China(“973”Program,No.2012CB625100)the Natural Science Foundation of Liaoning Province(No.2013020093)
文摘TiAIN]Cu nanocomposite coatings with Cu concentration of 0-1.4 at.% were deposited on the high- speed steel （HSS） substrates by filtered cathodic arc ion plating technique. The chemical composition, microstructure, morphology, adhesion strength, mechanical and tribological properties of the TiAIN/Cu coatings were characterized and analyzed. The results reveal that the coating structure and properties depend on not only the Cu concentration, hut also the deposition condition. The addition of Cu significantly decreases the grain size and weakens the texture in the TiAlN/Cu coatings. With increasing the Cu concentration, the coating hardness decreases slightly from 30.7 GPa of the pure TiAlN coating to 28.5 GPa of the TiAlN/Cu coating with 1.4 at,% Cu. All the TiAlN/Cu coatings present sufficient adhesion strength. In addition, the existing state of additive Cu in the TiAlN/Cu coatings is also investigated.
基金supported by the National Natural Science Foundation of China (Grant No.10502044,10772162)the Defense-based research project(Grant No.A1420080144)the Major projects on control and rectification of water body pollution (Grant No.2009ZX07424-001)
文摘An LES/FDF model was developed by the authors to investigate the SGS effect on the particle motion in the gas-particle two-phase plane wake flow.The simulation results of dispersion rate for different particles were compared with the results without using the FDF model.It was shown that the large eddy structure is the dominant factor influencing the particle diffu-sion in space for small particles(small Stokes-number particles),but for intermediate or large diameter particles,the influence of the sub-grid scale eddies on the dispersion rate is in the same order as that of the large eddies.The sub-grid scale eddies increase the particle dispersion rate in most time,but sometimes they decrease the dispersion rate.The sub-grid scale particle dispersion rate is decided not only by the intensity of sub-grid scale eddies and the Stokes number of the particles,but also by the large eddy structure of the flow field.For the particles in isotropic turbulence,the dispersion rate decreases as the particle diameter increases.
文摘In this paper we show that if R is a discrete valuation ring, then R is a filtered ring. We prove some properties and relation when R is a discrete valuation ring.
文摘Let R be a filtered Noetherian ring with identity and M an R-filtered module. The associated graded ring of R is denoted by G(R) and the associated graded G(R) module of M is denoted by gr(M). Bjork studied in ref. [1] the relation between M being a module with a good filtration and gr(M) being a finitely generated module. If R is a ring with positive filtration and G(R) is a Noetherian ring, then M is a module with good filtration if and only if gr(M) is a finitely generated G(R) module. But when R is a Zariski filtered ring,we do not know if the conclusion is true. To be specific, Bjork’s problem is:
基金supported by the National Key Research and Development Program of China(No.2018YFC2001100)the National Natural Science Foundation of China(No.62171441,82071314)the Scientific Research and Equipment Development Project of CAS(YJKYYQ20210031).
文摘Achieving passive microparticle filtration with micropore membranes is challenging due to the capillary pinning effect of the membranes.Inspired by the teapot effect that occurs when liquid(tea)is poured from a teapot spout,we proposed a tap-triggered self-wetting strategy and utilized the method with a 3D sieve to flter rare cells.First,a 3D-printed polymer tap-trigger microstructure was implemented.As a result,the 3μm micropore membrane gating threshold(the pressure needed to open the micropores)was lowered from above 3000 to 80 Pa by the tap-trigger microstructure that facilated the liquid leakage and spreading to self-wet more membrane area in a positive feedback loop.Then,we implemented a 3D cone-shaped cell sieve with tap-trigger microstructures.Driven by gravity,the sieve performed at a high throughput above 20 mL/min(DPBS),while the micropore size and porosity were 3μm and 14.1%,respectively.We further filtered leukocytes from whole blood samples with the proposed new 3D sieve,and the method was compared with the traditional method of leukocyte isolation by chemically removing red blood cells.The device exhibited comparable leukocyte purity but a higher platelet removal rate and lower leukocyte simulation level,facilitating downstream single-cell analysis.The key results indicated that the tap-triggered self-wetting strategy could significantly improve the performance of passive microparticle filtration.
基金Project supported by the Enterprise Science and Technology Correspondent for Guangdong Province,China (Grant No.GDKTP2021015200)。
文摘For the crystalline temperature of BaSnO_(3)(BTO)was above 650℃,the transparent conductive BTO-based films were always deposited above this temperature on epitaxy substrates by pulsed laser deposition or molecular beam epitaxy till now which limited there application in low temperature device process.In the article,the microstructure,optical and electrical of BTO and In_(2)O_(3) mixed transparent conductive BaInSnO_(x)(BITO)film deposited by filtered cathodic vacuum arc technique(FCVA)on glass substrate at room temperature were firstly reported.The BITO film with thickness of 300 nm had mainly In_(2)O_(3) polycrystalline phase,and minor polycrystalline BTO phase with(001),(011),(111),(002),(222)crystal faces which were first deposited at room temperature on amorphous glass.The transmittance was 70%–80%in the visible light region with linear refractive index of 1.94 and extinction coefficient of 0.004 at 550-nm wavelength.The basic optical properties included the real and imaginary parts,high frequency dielectric constants,the absorption coefficient,the Urbach energy,the indirect and direct band gaps,the oscillator and dispersion energies,the static refractive index and dielectric constant,the average oscillator wavelength,oscillator length strength,the linear and the third-order nonlinear optical susceptibilities,and the nonlinear refractive index were all calculated.The film was the n-type conductor with sheet resistance of 704.7Ω/□,resistivity of 0.02Ω⋅cm,mobility of 18.9 cm2/V⋅s,and carrier electron concentration of 1.6×10^(19) cm^(−3) at room temperature.The results suggested that the BITO film deposited by FCVA had potential application in transparent conductive films-based low temperature device process.
