The existence of the aeroengine casing,limited monitoring points,and multi-fault characteristics make obtaining the rotor’s vibration transmission characteristics challenging,resulting in difficulties accurately iden...The existence of the aeroengine casing,limited monitoring points,and multi-fault characteristics make obtaining the rotor’s vibration transmission characteristics challenging,resulting in difficulties accurately identifying the rotor unbalance.This paper utilizes a high-frequency composite sensor to monitor the engine’s blade tip clearance(BTC)and extracts unbalanced information from BTC signals for rotor dynamic balancing,while avoiding the need for the once per revolution(OPR)sensor.First,the vibration characteristics of the rotor-blade system under multi-fault conditions are investigated.Then,based on BTC measurement,a none OPR method and an unbalance identification method are proposed,in which the radial vibration of the blade tip in the BTC signals at different speeds is extracted and operated in the time domain to obtain the rotor unbalanced vibration,the signal is reconstructed,and cross-correlation analysis is used to accurately identify the magnitude and phase of the unbalanced signal.Finally,a rotor test bench is utilized for experimental verification.The results reveal that the dynamic balancing method based on the BTC signal can more precisely identify the rotor unbalance than the traditional rotor dynamic balancing method.The application of this technique will effectively improve engine health management and fault prediction.展开更多
A kind of piezoresistive response extraction method for smart cement-based composites/sensors was proposed.Two kinds of typical piezoresistive cement-based composites/sensors were fabricated by respectively adding car...A kind of piezoresistive response extraction method for smart cement-based composites/sensors was proposed.Two kinds of typical piezoresistive cement-based composites/sensors were fabricated by respectively adding carbon nanotubes and nickel powders as conductive fillers into cement paste or cement mortar.The variation in measured electrical resistance of such cement-based composites/sensors was explored without loading and under repeated compressive loading and impulsive loading.The experimental results indicate that the measured electrical resistance of piezoresistive cement-based composites/sensors exhibits a two-stage variation trend of fast increase and steady increase with measurement time without loading,and an irreversible increase after loading.This results from polarization caused by ionic conduction in these composites/sensors.After reaching a plateau,the measured electrical resistance can be divided into an electrical resistance part and an electrical capacity part.The piezoresistive responses of electrical resistance part in measured electrical resistance to loading can be extracted by eliminating the linear electrical capacity part in measured electrical resistance.展开更多
The development of a simple, efficient and sensitive sensor for dissolved oxygen is proposed using a novel type of porous carbon composite membrane/glassy carbon electrode based on the low-cost common filter paper by ...The development of a simple, efficient and sensitive sensor for dissolved oxygen is proposed using a novel type of porous carbon composite membrane/glassy carbon electrode based on the low-cost common filter paper by a simple method. The resulting device exhibited excellent electrocatalytic activities toward the oxygen reduction reaction. Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements demonstrated that the porous morphology and uniformly dispersed Fe;C nanoparticles of the PCCM play an important role in the oxygen reduction reaction. A linear response range from 2mmol/L up to 110 mmol/L and a detection limit of 1.4 mmol/L was obtained with this sensor. The repeatability of the proposed sensor,evaluated in terms of relative standard deviation, was 3.0%. The successful fabrication of PCCM/GC electrode may promote the development of new porous carbon oxygen reduction reaction material for the oxygen reduction sensor.展开更多
With the aid of the latest fiber optic sensing technology parameters in the cure process of ther- mosetting resin-matrix composite, such as temperature, viscosity,void and residual stress, can be monitored entirely an...With the aid of the latest fiber optic sensing technology parameters in the cure process of ther- mosetting resin-matrix composite, such as temperature, viscosity,void and residual stress, can be monitored entirely and efficiently.In this paper, experiment results of viscosity measurement in composite cure process in autoclave using fiber optic sensors are presented. Based on the sensed information, a computer program is utilized to control the cure process. With this technology, the cure process becomes more apparent and controllable, which will greatly improve the cured products and reduce the cost.展开更多
Graphene oxide （GO）-multiwalled carbon nanotube （MWCNT） composite was synthesized and characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, micro Raman, Fourier transform infra...Graphene oxide （GO）-multiwalled carbon nanotube （MWCNT） composite was synthesized and characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, micro Raman, Fourier transform infrared and ultraviolet-visible near infrared spectroscopy techniques. Spectral characteris- tics of cladding modified fiber optic gas sensors were studied for various concentrations of ammonia, ethanol and methanol at 27 ℃. Thickness of the gas sensing layer was controlled by varying the concentration of composite in ethanol medium （0.5 and 1 mg/mL） for three times dipping process. The O.S mg/ mL concentrated GO-MWCNT coated sensor showed 1.20, 1.40 and 1.15 times higher sensitivity than the GO coated sensor for ammonia, ethanol and methanol vapors, respectively. Furthermore, it exhibited 1.50, 1.80 and 1.80 times better sensitivity than 1 mg/mL concentrated GO-MWCNT coated sensor for ammonia, ethanol and methanol vapors, respectively. The presence of functional groups in GO increased the sen- sitivity. This is mainly attributed to the effective electron charge transfer between the composite materials and analytes.展开更多
Magnetic pressure sensors that employ magneto-elastomers to convert pressure stimuli into detectable magnetic signals are widely regarded as promising components for smart wearables.However,achieving both an ultralow ...Magnetic pressure sensors that employ magneto-elastomers to convert pressure stimuli into detectable magnetic signals are widely regarded as promising components for smart wearables.However,achieving both an ultralow detection limit and a broad sensing range within a single device remains a persistent challenge.Here,we present a magnetic amorphous-wire pressure sensor(MAWPS)that simultaneously attains these properties through a multilayer architecture designed to generate a tunable magnetic-field configuration.The device comprises a force-to-magnetic conversion unit(FMCU)and a magnetic sensing unit(MSU).The FMCU incorporates a composite magneto-elastomer formed by integrating cilia-type and film-type structures with opposite magnetization orientations.The magnetic cilia,characterized by low modulus,allows to detect subtle pressure,while the higher-modulus magnetic films modulate the intensity and direction of the magnetic field under larger pressure.This cooperative mechanism ensures that the magnetic field detected by magnetic amorphous wire of MSU remains within the sensitive range.As a result,the MAWPS exhibits a detection limit of 2.4 Pa,a sensing range exceeding 300 kPa,rapid response,and excellent stability.Furthermore,asymmetric wire placement enables shear-direction sensing ability.We further demonstrate the applicability in smart wearable scenarios,including respiratory monitoring,object grasping,morphology recognition,and stress direction sensing.展开更多
基金supported by the Key Program of National Natural Science Foundation of China(No.92160203)National Natural Science Foundation of China(No.92360306).
文摘The existence of the aeroengine casing,limited monitoring points,and multi-fault characteristics make obtaining the rotor’s vibration transmission characteristics challenging,resulting in difficulties accurately identifying the rotor unbalance.This paper utilizes a high-frequency composite sensor to monitor the engine’s blade tip clearance(BTC)and extracts unbalanced information from BTC signals for rotor dynamic balancing,while avoiding the need for the once per revolution(OPR)sensor.First,the vibration characteristics of the rotor-blade system under multi-fault conditions are investigated.Then,based on BTC measurement,a none OPR method and an unbalance identification method are proposed,in which the radial vibration of the blade tip in the BTC signals at different speeds is extracted and operated in the time domain to obtain the rotor unbalanced vibration,the signal is reconstructed,and cross-correlation analysis is used to accurately identify the magnitude and phase of the unbalanced signal.Finally,a rotor test bench is utilized for experimental verification.The results reveal that the dynamic balancing method based on the BTC signal can more precisely identify the rotor unbalance than the traditional rotor dynamic balancing method.The application of this technique will effectively improve engine health management and fault prediction.
基金Funded by the National Natural Science Foundation of China(Nos. 51178148,50808055)the Natural Scientific Research Innovation Foundation in Harbin Institute of Technology(No.HIT.NSRIF.2009096)the Program for New Century Excellent Talents University of China(No.NCET-0798)
文摘A kind of piezoresistive response extraction method for smart cement-based composites/sensors was proposed.Two kinds of typical piezoresistive cement-based composites/sensors were fabricated by respectively adding carbon nanotubes and nickel powders as conductive fillers into cement paste or cement mortar.The variation in measured electrical resistance of such cement-based composites/sensors was explored without loading and under repeated compressive loading and impulsive loading.The experimental results indicate that the measured electrical resistance of piezoresistive cement-based composites/sensors exhibits a two-stage variation trend of fast increase and steady increase with measurement time without loading,and an irreversible increase after loading.This results from polarization caused by ionic conduction in these composites/sensors.After reaching a plateau,the measured electrical resistance can be divided into an electrical resistance part and an electrical capacity part.The piezoresistive responses of electrical resistance part in measured electrical resistance to loading can be extracted by eliminating the linear electrical capacity part in measured electrical resistance.
基金the National Natural Science Foundation of China (No.21273097)the project from the State Key Laboratory of Electroanalytical Chemistry (No.2013)the Science Foundation of Jilin Province (No.20130204003GX)
文摘The development of a simple, efficient and sensitive sensor for dissolved oxygen is proposed using a novel type of porous carbon composite membrane/glassy carbon electrode based on the low-cost common filter paper by a simple method. The resulting device exhibited excellent electrocatalytic activities toward the oxygen reduction reaction. Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements demonstrated that the porous morphology and uniformly dispersed Fe;C nanoparticles of the PCCM play an important role in the oxygen reduction reaction. A linear response range from 2mmol/L up to 110 mmol/L and a detection limit of 1.4 mmol/L was obtained with this sensor. The repeatability of the proposed sensor,evaluated in terms of relative standard deviation, was 3.0%. The successful fabrication of PCCM/GC electrode may promote the development of new porous carbon oxygen reduction reaction material for the oxygen reduction sensor.
文摘With the aid of the latest fiber optic sensing technology parameters in the cure process of ther- mosetting resin-matrix composite, such as temperature, viscosity,void and residual stress, can be monitored entirely and efficiently.In this paper, experiment results of viscosity measurement in composite cure process in autoclave using fiber optic sensors are presented. Based on the sensed information, a computer program is utilized to control the cure process. With this technology, the cure process becomes more apparent and controllable, which will greatly improve the cured products and reduce the cost.
文摘Graphene oxide （GO）-multiwalled carbon nanotube （MWCNT） composite was synthesized and characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, micro Raman, Fourier transform infrared and ultraviolet-visible near infrared spectroscopy techniques. Spectral characteris- tics of cladding modified fiber optic gas sensors were studied for various concentrations of ammonia, ethanol and methanol at 27 ℃. Thickness of the gas sensing layer was controlled by varying the concentration of composite in ethanol medium （0.5 and 1 mg/mL） for three times dipping process. The O.S mg/ mL concentrated GO-MWCNT coated sensor showed 1.20, 1.40 and 1.15 times higher sensitivity than the GO coated sensor for ammonia, ethanol and methanol vapors, respectively. Furthermore, it exhibited 1.50, 1.80 and 1.80 times better sensitivity than 1 mg/mL concentrated GO-MWCNT coated sensor for ammonia, ethanol and methanol vapors, respectively. The presence of functional groups in GO increased the sen- sitivity. This is mainly attributed to the effective electron charge transfer between the composite materials and analytes.
基金supported by National Key R&D Program of China(2024YFB3814100)National Natural Science Foundation of China(U24A20228,U24A6001,52127803)+4 种基金supported by the Jiangxi Youth Science and Technology Talent Development Program(20244BCE52245)the General Scientific Research Project of the Jiangxi Provincial Department of Education(GJJ2401512)Doctoral research start-up project(JZB2403)Ji'an Key Science and Technology Program(20255-071665)Ningbo Key Research and Development Program(2024Z148,2024Z143,2024Z199,2024Z171).
文摘Magnetic pressure sensors that employ magneto-elastomers to convert pressure stimuli into detectable magnetic signals are widely regarded as promising components for smart wearables.However,achieving both an ultralow detection limit and a broad sensing range within a single device remains a persistent challenge.Here,we present a magnetic amorphous-wire pressure sensor(MAWPS)that simultaneously attains these properties through a multilayer architecture designed to generate a tunable magnetic-field configuration.The device comprises a force-to-magnetic conversion unit(FMCU)and a magnetic sensing unit(MSU).The FMCU incorporates a composite magneto-elastomer formed by integrating cilia-type and film-type structures with opposite magnetization orientations.The magnetic cilia,characterized by low modulus,allows to detect subtle pressure,while the higher-modulus magnetic films modulate the intensity and direction of the magnetic field under larger pressure.This cooperative mechanism ensures that the magnetic field detected by magnetic amorphous wire of MSU remains within the sensitive range.As a result,the MAWPS exhibits a detection limit of 2.4 Pa,a sensing range exceeding 300 kPa,rapid response,and excellent stability.Furthermore,asymmetric wire placement enables shear-direction sensing ability.We further demonstrate the applicability in smart wearable scenarios,including respiratory monitoring,object grasping,morphology recognition,and stress direction sensing.
