Listeria monocytogenes(LM)is a dangerous foodborne pathogen for humans.One emerging and validated method of indirectly assessing LM in food is detecting 3-hydroxy-2-butanone(3H2B)gas.In this study,the synthesis of 3-(...Listeria monocytogenes(LM)is a dangerous foodborne pathogen for humans.One emerging and validated method of indirectly assessing LM in food is detecting 3-hydroxy-2-butanone(3H2B)gas.In this study,the synthesis of 3-(2-aminoethylamino)propyltrimethoxysilane(AAPTMS)functionalized hierarchical hollow TiO_(2)nanospheres was achieved via precise controlling of solvothermal reaction temperature and post-grafting route.The sensors based on as-prepared materials exhibited excellent sensitivity(480 Hz@50 ppm),low detection limit(100 ppb),and outstanding selectivity.Moreover,the evaluation of LM with high sensitivity and specificity was achieved using the sensors.Such stable three-dimensional spheres,whose distinctive hierarchical and hollow nanostructure simultaneously improved both sensitivity and response/recovery speed dramatically,were spontaneously assembled by nanosheets.Meanwhile,the moderate loadings of AAPTMS significantly improved the selectivity of sensors.Then,the gas-sensing mechanism was explored by utilizing thermodynamic investigation,Gaussian 16 software,and in situ diffuse reflectance infrared transform spectroscopy,illustrating the weak chemisorption between the-NHgroup and 3H2B molecules.These portable sensors are promising for real-time assessment of LM at room temperature,which will make a magnificent contribution to food safety.展开更多
Fibrosis occurs due to the excessive deposition of extracellular matrix caused by cell injury.After various types of tissue injury,the dysregulation of the internal response can eventually lead to the destruction of o...Fibrosis occurs due to the excessive deposition of extracellular matrix caused by cell injury.After various types of tissue injury,the dysregulation of the internal response can eventually lead to the destruction of organ structure and dysfunction.There is increasing evidence that oxidative stress,which is characterized by excessive production of hydrogen peroxide(H_(2)O_(2)),is an important cause of fibrosis.Therefore,we synthesized a biosensitive and efficient electrochemical H_(2)O_(2)sensor based on PtNi nanoparticle-doped N-reduced graphene oxide(PtNi-N-rGO)to detect H_(2)O_(2)released from transforming growth factorβ1(TGFβ1)-induced myofibroblast.In addition,the sensor could easily detect changes in H_(2)O_(2)in the lung and bronchoalveolar lavage fluid(BALF)of mice with pulmonary fibrosis.Furthermore,the sensor could also detect H_(2)O_(2)in activated hepatic stellate cells and the liver of carbon tetrachloride(CCl_(4))-induced liver fibrosis.Moreover,the alterations in H_(2)O_(2)detected by the sensor were consistent with nicotinamide adenine dinucleotide phosphate oxidase 4(NOX4)protein expression and the staining results of pathological sections.Taken together,these results highlight the use of H_(2)O_(2)sensors for the rapid detection of fibrosis and facilitate the rapid evaluation of antifibrotic drug candidates.展开更多
A novel nonenzymatic glucose sensor was successfully fabricated based on the Cu2O polyhedrons covered Cu foil. The Cu2O polyhedrons covered Cu foil was constructed via a facile, low-cost and larger scale producible me...A novel nonenzymatic glucose sensor was successfully fabricated based on the Cu2O polyhedrons covered Cu foil. The Cu2O polyhedrons covered Cu foil was constructed via a facile, low-cost and larger scale producible method. The Cu2O polyhedrons covered Cu foil can be directly used as the working electrode of nonenzymatic glucose sensor, which present good stability and flexibility. The results indicated that the Cu2O polyhedrons modified Cu electrode （Cu2O/Cu electrode） showed high electrocatalytic activity for the oxidation of glucose in alkaline solution. There are two linear regions of glucose concentration for the glucose sensor based on Cu2O/Cu electrode, respectively in 10μmol/L to 0.53 mmol/L （sensitivity： 3029.33 μA （mmol/ L）^-1 cm^-2） and in 0.53-7.53 mmol/L （sensitivity： 728.67 μA （rnmol/L）^-1 cm^-2）.展开更多
The multiwalled carbon nanotubes thin-film-based electrode was fabricated by electrophoretic deposition and modified with copper （Cu） nanoparticles to fabricate Cu/CNTs nanocomposite sensor for nonenzymatic glucose ...The multiwalled carbon nanotubes thin-film-based electrode was fabricated by electrophoretic deposition and modified with copper （Cu） nanoparticles to fabricate Cu/CNTs nanocomposite sensor for nonenzymatic glucose detection. The expensive glassy carbon electrode was replaced by fluorine-doped tin oxide glass containing CNTs film to confine the Cu nanoparticles growth by electrodeposition through cyclic voltammetry （CV）. The ultraviolet visible and X-ray diffraction analysis revealed the successful deposition of Cu nanoparticles on the CNTs-modified electrode. The atomic force microscopy images confirrqed the morphology of electrodeposited Cu on CNTs film as uniformly dispersed particles. The electrocatalytic activity of electrode to the glucose oxidation was investigated in alkaline medium by CV and amperometric measurements. The fabricated sensor exhibited a fast response time of less than 5 s and the sensitivity of 314 μA rnM^-1 cm^-2 with linear concentration range （0.02-3.0 mM） having detection limit 10.0 μM. Due to simple preparation of sensor, Cu/CNTs nanocomposite electrodes are a suitable candidate for reliable determination of glucose with good stability.展开更多
An approach of position sensorless control for permanent magnet synchronous motor （ PMSM ） is put forward based on a sliding mode observer. The mathematical model of PMSM in a stationary αβ reference frame is adop...An approach of position sensorless control for permanent magnet synchronous motor （ PMSM ） is put forward based on a sliding mode observer. The mathematical model of PMSM in a stationary αβ reference frame is adopted, and the system is controlled by the digital signal processor （ DSP; TMS320LF2407 according to the control achieve closed loop operation of the motor, the stator theory of sliding mode observer. In order to magnetic field should be vertical with the rotor magnetic field and be synchronous with rotor rotating, so the position and speed of PMSM is estimated in real time and the estimated position is modified continuously. The simulation results indicate that the proposed observer has high precision is more robust to the parametric variation and load in estimation of PMSM position and speed, and torque disturbance.展开更多
Because brushless direct current(BLDC) motors have the advantages of a compact size, high power density, high efficiency, and long operating life time, they are widely used in many industrial products and electric tra...Because brushless direct current(BLDC) motors have the advantages of a compact size, high power density, high efficiency, and long operating life time, they are widely used in many industrial products and electric traction systems. It is known that the BLDC motors have no brushes for commutation. They are commutated with electronically commutation. So, the rotor position information of the BLDC motors must be known to understand which winding will be energized according to the energizing sequence. In most of the existing BLDC motor drivers, rotor position information is detected by Hall effect sensors. This kind of mechanical position sensors will bring additional connections and costs, reliability decrease and noise increase. In order to improve the control performance and extend the range of speed regulation for BLDC motors, a position sensorless control method is proposed in this paper. In the proposed control method, rotor position information of the BLDC motors is detected from the back electromagnetic forces(back-EMFs) which are estimated by an unknown-input observer with line to line currents and line to line voltages. For the purpose of verifying the effectiveness of the proposed control method, a model is built and simulated on the Matlab/Simulink platform. The simulation results show that the speed regulation performance of BLDC motors is improved compared with using Hall effect sensors. At the same time, the reliability of the BLDC motors is improved and the costs of them are reduced because the position sensor is eliminated.展开更多
We present a theoretic model to calculate skin depths and eddy-current power losses for a magnetic position sensor. Eddy-current, arised from the operation of an alternating-current excitation, induces secondary curre...We present a theoretic model to calculate skin depths and eddy-current power losses for a magnetic position sensor. Eddy-current, arised from the operation of an alternating-current excitation, induces secondary currents and fields between magnetic material and magnetic position sensor. In this paper, a magnetic position sensor system is simplified to be an outer-winding coil along the axial direction of a low carbon steel bar. The analytical model is derived from basic field and circuit theory considering a linear approximation for a nonlinear permeability. Thus the skin depths and eddy-current power losses from the model in eddy-current modeling techniques at various frequencies of an excited current source can be calculated. The proposed configuration is capable of predicting the skin depths and eddy-current power losses for a magnetic position sensor and has a consistence with experiments.展开更多
In this paper,position sensorless control system of permanent magnet synchronous linear motor(PMSLM)based on sliding mode observer(SMO)with an improved phase-locked loop(PLL)is studied.Firstly,according to the mathema...In this paper,position sensorless control system of permanent magnet synchronous linear motor(PMSLM)based on sliding mode observer(SMO)with an improved phase-locked loop(PLL)is studied.Firstly,according to the mathematical model,a SMO is designed for sensorless control PMSLM drive.Thereafter,an improved PLL is proposed to tackle the imperfection of data overflow existed in the traditional PLL.The designed SMO incorporating with the improved PLL can be effectively suppress the pulsation of the estimated position and hence the chattering of the derived electrical angular velocity.At last,simulated and experimental results are presented to verify the effectiveness and feasibility of the position sensorless control system.展开更多
A onvel current chopping strategy for switched reluc-tance generator(SRG)-a full conducted current chopping(FCCC)scheme is presented,According to characteristics lf phase current wave of SRG generating operation,it ca...A onvel current chopping strategy for switched reluc-tance generator(SRG)-a full conducted current chopping(FCCC)scheme is presented,According to characteristics lf phase current wave of SRG generating operation,it can be generated under sensorless condition without an addi-tional circuit or a position signal algorithm.Simulational results show the feasibility of this scheme.Experimental results of a 6kW6/4configuration SRG show its simplic-ity and high reliability with little decrease in efficiency.Soit will be widely used.展开更多
In order to realize the micromation of position sensors, and extend the application area into micro scale, this paper designs a novel micro position sensor, Mace SAW (Surface Acoustic Wave) position sensor, which can ...In order to realize the micromation of position sensors, and extend the application area into micro scale, this paper designs a novel micro position sensor, Mace SAW (Surface Acoustic Wave) position sensor, which can be fabricated with MEMS technology. Its key components are IDTs (Interdigital Transducers) and reflective grooves. The structure and working principles of the sensor are introduced theoretically, and the manufacture process is then put forward.展开更多
The Prussian blue nanoparticles（PBNPs） were prepared by a self-assembly process, on a glassy carbon（GC） electrode modified with a poly（o-phenylenediamine）（Po PD） film. The stepwise fabrication process of PBNPs...The Prussian blue nanoparticles（PBNPs） were prepared by a self-assembly process, on a glassy carbon（GC） electrode modified with a poly（o-phenylenediamine）（Po PD） film. The stepwise fabrication process of PBNPs-modified Po PD/GCE was characterized by scanning electron microscopy（SEM） and electrochemical impedance spectroscopy. The prepared PBNPs showed an average size of 70 nm and a homogeneous distribution on the surface of modified electrodes. The PBNPs/Po PD/GCE showed adequate mechanical, electrochemical stability and good sensitivity in comparison with other PB based H2O2 sensors. The present modified electrode exhibited a linear response for H2O2 reduction over the concentration range of 1–58.22 mmol L ^-1with a detection limit of ca. 0.8 mmol L ^-1（S/N = 3）, and sensitivity of 3187.89 m A（mol L ^-1） ^-1cm ^-2using the amperometric method. This sensor was employed for the H2O2 determination in real sample and also exhibited good interference resistance and selectivity.展开更多
A tip-tilt-piston 3×3 electrothermal micromirror array(MMA)integrated with temperature field-based position sensors is designed and fabricated in this work.The size of the individual octagonal mirror plates is as...A tip-tilt-piston 3×3 electrothermal micromirror array(MMA)integrated with temperature field-based position sensors is designed and fabricated in this work.The size of the individual octagonal mirror plates is as large as 1.6 mm×1.6 mm.Thermal isolation structures are embedded to reduce the thermal coupling among the micromirror units.Results show that each micromirror unit has a piston scan range of 218μm and a tip-tilt optical scan angle of 21°at only 5 Vdc.The micromirrors also exhibit good dynamic performance with a rise time of 51.2 ms and a fall time of 53.6 ms.Moreover,the on-chip position sensors are proven to be capable for covering the full-range movement of the mirror plate,with the measured sensitivities of 1.5 mV/μm and 8.8 mV/°in piston sensing and tip-tilt sensing,respectively.Furthermore,the thermal crosstalk in an operating MMA has been experimentally studied.The measured results are promising thanks to the embedded thermal isolation structures.展开更多
The large-scale touch position sensor as a key human-machine interface toolkit holds immense significance in smart city and home construction.However,prior alternatives suffer from high power consumption,material limi...The large-scale touch position sensor as a key human-machine interface toolkit holds immense significance in smart city and home construction.However,prior alternatives suffer from high power consumption,material limitations,and implementation costs.Herein,a self-powered and scalable touch position strategy that integrates contact electrification with a screen-printing technique is proposed.Simply,high-impedance electrodes with stagger patterns are screen-printed onto various substrates before being covered with a dielectric layer.The locating mechanism originates from the touch-generated triboelectric charge shunt effect in the electrodes.The screen-printing parameters that affect the positional accuracy are discussed in detail.Leveraging this strategy,we realize a tailorable and large-scale triboelectric touch position sensor(LTTPS)that offers flexibility,self-powered capability,and a minimized signal channel,making it suitable for various practical scenarios.Demonstrations include an intelligent bookshelf mat with book management functionality,a rollable and foldable film-like keyboard,and a 4 m2 walk-tracking carpet.The LTTPS in this work provides an appealing alternative for large-scale touch positioning and enriches human-machine interaction.展开更多
In this paper, we consider the semilinear equation involving the fractional Laplacian in the Euclidian space R^n：（-△）^α/2u（x） ： f（xn）u^p（x）, x ∈R^n（0.1）in the subcritical case with 1〈 p〈n＋a/n-a.Inste...In this paper, we consider the semilinear equation involving the fractional Laplacian in the Euclidian space R^n：（-△）^α/2u（x） ： f（xn）u^p（x）, x ∈R^n（0.1）in the subcritical case with 1〈 p〈n＋a/n-a.Instead of carrying out direct investigations on pseudo-differential equation （0.1）, we first seek its equivalent form in an integral equation as below：u（x）=∫R^nG∞（x, y） f（yn） u^p（y）dy,where G∞（x, y） is the Green＇s function associated with the fractional Laplacian in R^n. Employing the method of moving planes in integral forms, we are able to derive the nonexistence of positive solutions for （0.2） in the subcritical case. Thanks to the equivalence, same con- clusion is true for （0.1）.展开更多
The hexagonal （h）-WO3-Cr2o3 nanocomposites with different W/Cr molar ratio of 4：1,10：1 and 40：1 were prepared by a facile two-step hydrothermal method, and its gas sensing properties were investigated under optim...The hexagonal （h）-WO3-Cr2o3 nanocomposites with different W/Cr molar ratio of 4：1,10：1 and 40：1 were prepared by a facile two-step hydrothermal method, and its gas sensing properties were investigated under optimum working temperature. X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, high resolution transmission electron microscopy （HRTEM） were used to characterize the morphology, microstructure and crystallinity of the as-synthesized samples. The hexagonal WO3 nanorods show a better crystallinity than Cr2O3 nanoparticles. When the molar ratio of W/Cr is 10：1, the hexagonal WO3-Cr2O3 nanocomposite shows obvious selectivity toward 2-butanone at 205℃ compared with other typical reducing gases, and the response value to 100 ppm 2- butanone can reach 5.6. However, there is no selectivity toward 2-butanone when the Cr/W molar ratio is 1：4 and 1：40. Furthermore, hexagonal WO3-Cr2O3 nanocomposites have a short response and recovery time to 5ppm 2-butanone, which is lOs and 80s, respectively. The measured results indicate that hexagonal WO3-Cr2O3 nanocomposite is a potential gas sensing material for monitoring volatile organic compounds （VOCs）.展开更多
Numerous arthropods evolve and optimize sensory systems, enabling them to effectively adapt complex and competitive habitats. Typically, scorpions can precisely perceive the prey location with the lowest metabolic rat...Numerous arthropods evolve and optimize sensory systems, enabling them to effectively adapt complex and competitive habitats. Typically, scorpions can precisely perceive the prey location with the lowest metabolic rate among invertebrates. This biological phenomenon contrasts sharply with engineered systems, which generally associates high accuracy with substantial energy consumption. Inspired by the Scorpion Compound Slit Sensilla (SCSS) with a stress field modulation strategy, a bionic positioning sensor with superior precision and minimal power consumption is developed for the first time, which utilizes the particular Minimum Positioning Units (MPUs) to efficiently locate vibration signals. The single MPU of the SCSS can recognize the direction of collinear loads by regulating the stress field distribution and further, the coupling action of three MPUs can realize all-angle vibration monitoring in plane. Experiments demonstrate that the bionic positioning sensor achieves 1.43 degrees of angle-error-free accuracy without additional energy supply. As a proof of concept, two bionic positioning sensors and machine learning algorithm are integrated to provide centimeter (cm)-accuracy target localization, ideally suited for the man-machine interaction. The novel design offers a new mechanism for the design of traditional positioning devices, improving precision and efficiency in both the meta-universe and real-world Internet-connected systems.展开更多
Aim To obtain new criteria for asymptotic behavior and nonexistence of positive solutions of nonlinear neutral delay difference equations. Methods By means of Hlder inequality and a method of direct analysis, some i...Aim To obtain new criteria for asymptotic behavior and nonexistence of positive solutions of nonlinear neutral delay difference equations. Methods By means of Hlder inequality and a method of direct analysis, some interesting Lemmas were offered. Results and Conclusion New criteria for asymptotic behavior and nonexistence of positive solutions of nonlinear neutral delay difference equations are established, which extend and improve the results obtained in the literature. Some interesting examples illustrating the importance of our results are also included.展开更多
The paper studies a class of nonlinear elliptic partial differential equations on a compact Riemannian manifold （M,g） with some curvature restriction. The authors try to prove some uniqueness and nonexistent results...The paper studies a class of nonlinear elliptic partial differential equations on a compact Riemannian manifold （M,g） with some curvature restriction. The authors try to prove some uniqueness and nonexistent results for the positive solutions of the equations concerned.展开更多
In order to solve the problem that the star point positioning accuracy of the star sensor in near space is decreased due to atmospheric background stray light and rapid maneuvering of platform, this paper proposes a s...In order to solve the problem that the star point positioning accuracy of the star sensor in near space is decreased due to atmospheric background stray light and rapid maneuvering of platform, this paper proposes a star point positioning algorithm based on the capsule network whose input and output are both vectors. First, a PCTL (Probability-Coordinate Transformation Layer) is designed to represent the mapping relationship between the probability output of the capsule network and the star point sub-pixel coordinates. Then, Coordconv Layer is introduced to implement explicit encoding of space information and the probability is used as the centroid weight to achieve the conversion between probability and star point sub-pixel coordinates, which improves the network’s ability to perceive star point positions. Finally, based on the dynamic imaging principle of star sensors and the characteristics of near-space environment, a star map dataset for algorithm training and testing is constructed. The simulation results show that the proposed algorithm reduces the MAE (Mean Absolute Error) and RMSE (Root Mean Square Error) of the star point positioning by 36.1% and 41.7% respectively compared with the traditional algorithm. The research results can provide important theory and technical support for the scheme design, index demonstration, test and evaluation of large dynamic star sensors in near space.展开更多
The accuracy of center height detection for corrugated beam guardrails is significantly affected by robot posture in the mobile highway guardrail detection systems based on structured light vision.To address the probl...The accuracy of center height detection for corrugated beam guardrails is significantly affected by robot posture in the mobile highway guardrail detection systems based on structured light vision.To address the problem,this paper proposes an integrated calibration method for structured light vision sensors.In the proposed system,the sensor is mounted on a crawler-type mobile robot,which scans and measures the center height of guardrails while in motion.However,due to external disturbances such as uneven road surfaces and vehicle vibrations,the posture of the robot may deviate,causing displacement of the sensor platform and resulting in spatial 3D measurement errors.To overcome this issue,the system integrates inertial measurement unit(IMU)data into the sensor calibration process,enabling realtime correction of posture deviations through sensor fusion.This approach achieves a unified calibration of the structured light vision system,effectively compensates for posture-induced errors,and enhances detection accuracy.A prototype was developed and tested in both laboratory and real highway environments.Experimental results demonstrate that the proposed method enables accurate center height detection of guardrails under complex road conditions,significantly reduces posture-related measurement errors,and greatly improves the efficiency and reliability of traditional detection methods.展开更多
基金supported by the National Natural Science Foundation of China(No.32272399)the Shanghai Natural Science Foundation(No.21ZR1427500).
文摘Listeria monocytogenes(LM)is a dangerous foodborne pathogen for humans.One emerging and validated method of indirectly assessing LM in food is detecting 3-hydroxy-2-butanone(3H2B)gas.In this study,the synthesis of 3-(2-aminoethylamino)propyltrimethoxysilane(AAPTMS)functionalized hierarchical hollow TiO_(2)nanospheres was achieved via precise controlling of solvothermal reaction temperature and post-grafting route.The sensors based on as-prepared materials exhibited excellent sensitivity(480 Hz@50 ppm),low detection limit(100 ppb),and outstanding selectivity.Moreover,the evaluation of LM with high sensitivity and specificity was achieved using the sensors.Such stable three-dimensional spheres,whose distinctive hierarchical and hollow nanostructure simultaneously improved both sensitivity and response/recovery speed dramatically,were spontaneously assembled by nanosheets.Meanwhile,the moderate loadings of AAPTMS significantly improved the selectivity of sensors.Then,the gas-sensing mechanism was explored by utilizing thermodynamic investigation,Gaussian 16 software,and in situ diffuse reflectance infrared transform spectroscopy,illustrating the weak chemisorption between the-NHgroup and 3H2B molecules.These portable sensors are promising for real-time assessment of LM at room temperature,which will make a magnificent contribution to food safety.
基金supported by the National Natural Science Foundation of Sichuan Province(Nos.2022NSFSC1465,2023NSFSC0525)Post-Doctor Research Project,West China Hospital,Sichuan University(No.2021HXBH086)+1 种基金the Sichuan University postdoctoral interdisciplinary Innovation Fund(No.10822041A2118)Full-Time Postdoctoral Research Fund of Sichuan University(No.20826041F4134)。
文摘Fibrosis occurs due to the excessive deposition of extracellular matrix caused by cell injury.After various types of tissue injury,the dysregulation of the internal response can eventually lead to the destruction of organ structure and dysfunction.There is increasing evidence that oxidative stress,which is characterized by excessive production of hydrogen peroxide(H_(2)O_(2)),is an important cause of fibrosis.Therefore,we synthesized a biosensitive and efficient electrochemical H_(2)O_(2)sensor based on PtNi nanoparticle-doped N-reduced graphene oxide(PtNi-N-rGO)to detect H_(2)O_(2)released from transforming growth factorβ1(TGFβ1)-induced myofibroblast.In addition,the sensor could easily detect changes in H_(2)O_(2)in the lung and bronchoalveolar lavage fluid(BALF)of mice with pulmonary fibrosis.Furthermore,the sensor could also detect H_(2)O_(2)in activated hepatic stellate cells and the liver of carbon tetrachloride(CCl_(4))-induced liver fibrosis.Moreover,the alterations in H_(2)O_(2)detected by the sensor were consistent with nicotinamide adenine dinucleotide phosphate oxidase 4(NOX4)protein expression and the staining results of pathological sections.Taken together,these results highlight the use of H_(2)O_(2)sensors for the rapid detection of fibrosis and facilitate the rapid evaluation of antifibrotic drug candidates.
基金supported by the Universities Natural Science Foundation of Jiangsu Province (No. 11KJB480001)Postdoctoral Foundation of Jiangsu Province (No. 1102125C)Highly Qualified Professional Initial Funding of Jiangsu University (No. 10JDG120)
文摘A novel nonenzymatic glucose sensor was successfully fabricated based on the Cu2O polyhedrons covered Cu foil. The Cu2O polyhedrons covered Cu foil was constructed via a facile, low-cost and larger scale producible method. The Cu2O polyhedrons covered Cu foil can be directly used as the working electrode of nonenzymatic glucose sensor, which present good stability and flexibility. The results indicated that the Cu2O polyhedrons modified Cu electrode （Cu2O/Cu electrode） showed high electrocatalytic activity for the oxidation of glucose in alkaline solution. There are two linear regions of glucose concentration for the glucose sensor based on Cu2O/Cu electrode, respectively in 10μmol/L to 0.53 mmol/L （sensitivity： 3029.33 μA （mmol/ L）^-1 cm^-2） and in 0.53-7.53 mmol/L （sensitivity： 728.67 μA （rnmol/L）^-1 cm^-2）.
基金supported by the University of Engineering and Technology, Lahore, Pakistan
文摘The multiwalled carbon nanotubes thin-film-based electrode was fabricated by electrophoretic deposition and modified with copper （Cu） nanoparticles to fabricate Cu/CNTs nanocomposite sensor for nonenzymatic glucose detection. The expensive glassy carbon electrode was replaced by fluorine-doped tin oxide glass containing CNTs film to confine the Cu nanoparticles growth by electrodeposition through cyclic voltammetry （CV）. The ultraviolet visible and X-ray diffraction analysis revealed the successful deposition of Cu nanoparticles on the CNTs-modified electrode. The atomic force microscopy images confirrqed the morphology of electrodeposited Cu on CNTs film as uniformly dispersed particles. The electrocatalytic activity of electrode to the glucose oxidation was investigated in alkaline medium by CV and amperometric measurements. The fabricated sensor exhibited a fast response time of less than 5 s and the sensitivity of 314 μA rnM^-1 cm^-2 with linear concentration range （0.02-3.0 mM） having detection limit 10.0 μM. Due to simple preparation of sensor, Cu/CNTs nanocomposite electrodes are a suitable candidate for reliable determination of glucose with good stability.
文摘An approach of position sensorless control for permanent magnet synchronous motor （ PMSM ） is put forward based on a sliding mode observer. The mathematical model of PMSM in a stationary αβ reference frame is adopted, and the system is controlled by the digital signal processor （ DSP; TMS320LF2407 according to the control achieve closed loop operation of the motor, the stator theory of sliding mode observer. In order to magnetic field should be vertical with the rotor magnetic field and be synchronous with rotor rotating, so the position and speed of PMSM is estimated in real time and the estimated position is modified continuously. The simulation results indicate that the proposed observer has high precision is more robust to the parametric variation and load in estimation of PMSM position and speed, and torque disturbance.
文摘Because brushless direct current(BLDC) motors have the advantages of a compact size, high power density, high efficiency, and long operating life time, they are widely used in many industrial products and electric traction systems. It is known that the BLDC motors have no brushes for commutation. They are commutated with electronically commutation. So, the rotor position information of the BLDC motors must be known to understand which winding will be energized according to the energizing sequence. In most of the existing BLDC motor drivers, rotor position information is detected by Hall effect sensors. This kind of mechanical position sensors will bring additional connections and costs, reliability decrease and noise increase. In order to improve the control performance and extend the range of speed regulation for BLDC motors, a position sensorless control method is proposed in this paper. In the proposed control method, rotor position information of the BLDC motors is detected from the back electromagnetic forces(back-EMFs) which are estimated by an unknown-input observer with line to line currents and line to line voltages. For the purpose of verifying the effectiveness of the proposed control method, a model is built and simulated on the Matlab/Simulink platform. The simulation results show that the speed regulation performance of BLDC motors is improved compared with using Hall effect sensors. At the same time, the reliability of the BLDC motors is improved and the costs of them are reduced because the position sensor is eliminated.
文摘We present a theoretic model to calculate skin depths and eddy-current power losses for a magnetic position sensor. Eddy-current, arised from the operation of an alternating-current excitation, induces secondary currents and fields between magnetic material and magnetic position sensor. In this paper, a magnetic position sensor system is simplified to be an outer-winding coil along the axial direction of a low carbon steel bar. The analytical model is derived from basic field and circuit theory considering a linear approximation for a nonlinear permeability. Thus the skin depths and eddy-current power losses from the model in eddy-current modeling techniques at various frequencies of an excited current source can be calculated. The proposed configuration is capable of predicting the skin depths and eddy-current power losses for a magnetic position sensor and has a consistence with experiments.
文摘In this paper,position sensorless control system of permanent magnet synchronous linear motor(PMSLM)based on sliding mode observer(SMO)with an improved phase-locked loop(PLL)is studied.Firstly,according to the mathematical model,a SMO is designed for sensorless control PMSLM drive.Thereafter,an improved PLL is proposed to tackle the imperfection of data overflow existed in the traditional PLL.The designed SMO incorporating with the improved PLL can be effectively suppress the pulsation of the estimated position and hence the chattering of the derived electrical angular velocity.At last,simulated and experimental results are presented to verify the effectiveness and feasibility of the position sensorless control system.
文摘A onvel current chopping strategy for switched reluc-tance generator(SRG)-a full conducted current chopping(FCCC)scheme is presented,According to characteristics lf phase current wave of SRG generating operation,it can be generated under sensorless condition without an addi-tional circuit or a position signal algorithm.Simulational results show the feasibility of this scheme.Experimental results of a 6kW6/4configuration SRG show its simplic-ity and high reliability with little decrease in efficiency.Soit will be widely used.
文摘In order to realize the micromation of position sensors, and extend the application area into micro scale, this paper designs a novel micro position sensor, Mace SAW (Surface Acoustic Wave) position sensor, which can be fabricated with MEMS technology. Its key components are IDTs (Interdigital Transducers) and reflective grooves. The structure and working principles of the sensor are introduced theoretically, and the manufacture process is then put forward.
基金University of Mazandaran,Babolsar,for their support
文摘The Prussian blue nanoparticles（PBNPs） were prepared by a self-assembly process, on a glassy carbon（GC） electrode modified with a poly（o-phenylenediamine）（Po PD） film. The stepwise fabrication process of PBNPs-modified Po PD/GCE was characterized by scanning electron microscopy（SEM） and electrochemical impedance spectroscopy. The prepared PBNPs showed an average size of 70 nm and a homogeneous distribution on the surface of modified electrodes. The PBNPs/Po PD/GCE showed adequate mechanical, electrochemical stability and good sensitivity in comparison with other PB based H2O2 sensors. The present modified electrode exhibited a linear response for H2O2 reduction over the concentration range of 1–58.22 mmol L ^-1with a detection limit of ca. 0.8 mmol L ^-1（S/N = 3）, and sensitivity of 3187.89 m A（mol L ^-1） ^-1cm ^-2using the amperometric method. This sensor was employed for the H2O2 determination in real sample and also exhibited good interference resistance and selectivity.
基金funded in part by National Natural Science Foundation of China under Grants 62350710218,92373105 and 62074015National Key Research and Development Program of China(2023YFB3507300).
文摘A tip-tilt-piston 3×3 electrothermal micromirror array(MMA)integrated with temperature field-based position sensors is designed and fabricated in this work.The size of the individual octagonal mirror plates is as large as 1.6 mm×1.6 mm.Thermal isolation structures are embedded to reduce the thermal coupling among the micromirror units.Results show that each micromirror unit has a piston scan range of 218μm and a tip-tilt optical scan angle of 21°at only 5 Vdc.The micromirrors also exhibit good dynamic performance with a rise time of 51.2 ms and a fall time of 53.6 ms.Moreover,the on-chip position sensors are proven to be capable for covering the full-range movement of the mirror plate,with the measured sensitivities of 1.5 mV/μm and 8.8 mV/°in piston sensing and tip-tilt sensing,respectively.Furthermore,the thermal crosstalk in an operating MMA has been experimentally studied.The measured results are promising thanks to the embedded thermal isolation structures.
基金National Key Research and Development Program,Grant/Award Number:2021YFA1201602NSFC,Grant/Award Numbers:T2422003,52302219Fundamental Research Funds for the Central Universities,Grant/Award Numbers:2024CDTZCQ-012,2024CDJGF-031。
文摘The large-scale touch position sensor as a key human-machine interface toolkit holds immense significance in smart city and home construction.However,prior alternatives suffer from high power consumption,material limitations,and implementation costs.Herein,a self-powered and scalable touch position strategy that integrates contact electrification with a screen-printing technique is proposed.Simply,high-impedance electrodes with stagger patterns are screen-printed onto various substrates before being covered with a dielectric layer.The locating mechanism originates from the touch-generated triboelectric charge shunt effect in the electrodes.The screen-printing parameters that affect the positional accuracy are discussed in detail.Leveraging this strategy,we realize a tailorable and large-scale triboelectric touch position sensor(LTTPS)that offers flexibility,self-powered capability,and a minimized signal channel,making it suitable for various practical scenarios.Demonstrations include an intelligent bookshelf mat with book management functionality,a rollable and foldable film-like keyboard,and a 4 m2 walk-tracking carpet.The LTTPS in this work provides an appealing alternative for large-scale touch positioning and enriches human-machine interaction.
文摘In this paper, we consider the semilinear equation involving the fractional Laplacian in the Euclidian space R^n：（-△）^α/2u（x） ： f（xn）u^p（x）, x ∈R^n（0.1）in the subcritical case with 1〈 p〈n＋a/n-a.Instead of carrying out direct investigations on pseudo-differential equation （0.1）, we first seek its equivalent form in an integral equation as below：u（x）=∫R^nG∞（x, y） f（yn） u^p（y）dy,where G∞（x, y） is the Green＇s function associated with the fractional Laplacian in R^n. Employing the method of moving planes in integral forms, we are able to derive the nonexistence of positive solutions for （0.2） in the subcritical case. Thanks to the equivalence, same con- clusion is true for （0.1）.
基金supported by the National Natural Science Foundation of China(Nos. 21303118, 51573137)the Doctor Projectfor Young Teachers of Ministry of Education(No. 20130032120003)the Seed Foundation of Tianjin University(No. 1501)
文摘The hexagonal （h）-WO3-Cr2o3 nanocomposites with different W/Cr molar ratio of 4：1,10：1 and 40：1 were prepared by a facile two-step hydrothermal method, and its gas sensing properties were investigated under optimum working temperature. X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, high resolution transmission electron microscopy （HRTEM） were used to characterize the morphology, microstructure and crystallinity of the as-synthesized samples. The hexagonal WO3 nanorods show a better crystallinity than Cr2O3 nanoparticles. When the molar ratio of W/Cr is 10：1, the hexagonal WO3-Cr2O3 nanocomposite shows obvious selectivity toward 2-butanone at 205℃ compared with other typical reducing gases, and the response value to 100 ppm 2- butanone can reach 5.6. However, there is no selectivity toward 2-butanone when the Cr/W molar ratio is 1：4 and 1：40. Furthermore, hexagonal WO3-Cr2O3 nanocomposites have a short response and recovery time to 5ppm 2-butanone, which is lOs and 80s, respectively. The measured results indicate that hexagonal WO3-Cr2O3 nanocomposite is a potential gas sensing material for monitoring volatile organic compounds （VOCs）.
基金supported by the National Natural Science Foundation of China(No.52175269)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52021003)+2 种基金Science and Technology Research Project of Education Department of Jilin Province(JJKH20231146KJ,JJKH20241262KJ)Project ZR2024ME104 supported by Shandong Provincial Natural Science FoundationChina Postdoctoral Science Foundation(No.2024M751086).
文摘Numerous arthropods evolve and optimize sensory systems, enabling them to effectively adapt complex and competitive habitats. Typically, scorpions can precisely perceive the prey location with the lowest metabolic rate among invertebrates. This biological phenomenon contrasts sharply with engineered systems, which generally associates high accuracy with substantial energy consumption. Inspired by the Scorpion Compound Slit Sensilla (SCSS) with a stress field modulation strategy, a bionic positioning sensor with superior precision and minimal power consumption is developed for the first time, which utilizes the particular Minimum Positioning Units (MPUs) to efficiently locate vibration signals. The single MPU of the SCSS can recognize the direction of collinear loads by regulating the stress field distribution and further, the coupling action of three MPUs can realize all-angle vibration monitoring in plane. Experiments demonstrate that the bionic positioning sensor achieves 1.43 degrees of angle-error-free accuracy without additional energy supply. As a proof of concept, two bionic positioning sensors and machine learning algorithm are integrated to provide centimeter (cm)-accuracy target localization, ideally suited for the man-machine interaction. The novel design offers a new mechanism for the design of traditional positioning devices, improving precision and efficiency in both the meta-universe and real-world Internet-connected systems.
文摘Aim To obtain new criteria for asymptotic behavior and nonexistence of positive solutions of nonlinear neutral delay difference equations. Methods By means of Hlder inequality and a method of direct analysis, some interesting Lemmas were offered. Results and Conclusion New criteria for asymptotic behavior and nonexistence of positive solutions of nonlinear neutral delay difference equations are established, which extend and improve the results obtained in the literature. Some interesting examples illustrating the importance of our results are also included.
文摘The paper studies a class of nonlinear elliptic partial differential equations on a compact Riemannian manifold （M,g） with some curvature restriction. The authors try to prove some uniqueness and nonexistent results for the positive solutions of the equations concerned.
文摘In order to solve the problem that the star point positioning accuracy of the star sensor in near space is decreased due to atmospheric background stray light and rapid maneuvering of platform, this paper proposes a star point positioning algorithm based on the capsule network whose input and output are both vectors. First, a PCTL (Probability-Coordinate Transformation Layer) is designed to represent the mapping relationship between the probability output of the capsule network and the star point sub-pixel coordinates. Then, Coordconv Layer is introduced to implement explicit encoding of space information and the probability is used as the centroid weight to achieve the conversion between probability and star point sub-pixel coordinates, which improves the network’s ability to perceive star point positions. Finally, based on the dynamic imaging principle of star sensors and the characteristics of near-space environment, a star map dataset for algorithm training and testing is constructed. The simulation results show that the proposed algorithm reduces the MAE (Mean Absolute Error) and RMSE (Root Mean Square Error) of the star point positioning by 36.1% and 41.7% respectively compared with the traditional algorithm. The research results can provide important theory and technical support for the scheme design, index demonstration, test and evaluation of large dynamic star sensors in near space.
基金Supported by the Special Fund for Basic Scientific Research of Central-Level Public Welfare Scientific Research Institutes(2024-9007)。
文摘The accuracy of center height detection for corrugated beam guardrails is significantly affected by robot posture in the mobile highway guardrail detection systems based on structured light vision.To address the problem,this paper proposes an integrated calibration method for structured light vision sensors.In the proposed system,the sensor is mounted on a crawler-type mobile robot,which scans and measures the center height of guardrails while in motion.However,due to external disturbances such as uneven road surfaces and vehicle vibrations,the posture of the robot may deviate,causing displacement of the sensor platform and resulting in spatial 3D measurement errors.To overcome this issue,the system integrates inertial measurement unit(IMU)data into the sensor calibration process,enabling realtime correction of posture deviations through sensor fusion.This approach achieves a unified calibration of the structured light vision system,effectively compensates for posture-induced errors,and enhances detection accuracy.A prototype was developed and tested in both laboratory and real highway environments.Experimental results demonstrate that the proposed method enables accurate center height detection of guardrails under complex road conditions,significantly reduces posture-related measurement errors,and greatly improves the efficiency and reliability of traditional detection methods.
