The present invention provides a wireless temperature and humidity sensor and system, and measurement method. The wireless temperature and humidity sensor comprises a substrate, a feeding network, an antenna and surface acoustic wave resonators, wherein the surface acoustic wave resonators are fed by said feeding network through said antenna. Said surface acoustic wave resonator comprises a reference resonator and measuring resonators. The resonant frequency difference between said reference resonator and said measuring resonators is used to modulate the temperature and/or humidity to be measured. Said system can monitor both temperature and humidity simultaneously, or monitor humidity or temperature selectively. Furthermore, frequency drift caused by aging of the sensor material and the connector is effectively suppressed by the differential modulation, thereby improving long-term stability of measurement and avoiding recalibration.

Wireless temperature and humidity sensor and system, and measurement method

The invention belongs to the field of nondestructive testing, and relates to a ray tracing type ultrasonic Lamb wave defect tomographic imaging method, first, a to-be-measured material imaging area is divided into a plurality of small grids, and the same amount of emission EMAT (electro-magnetic acoustic transducer) and receiving EMAT are arranged on both sides of the area, then all emission ends are allowed to excite A0 mode Lamb wave, all receiving ends at the opposite side receive meanwhile, analysis results of all tested waveforms are extracted, the corresponding time is recorded, the slowness and defect distribution of every grids are determined by use of combined iterative reconstruction algorithm, the obtained defect distribution is used as a known condition for establishment of a RT extrapolation formula, by use of the extrapolation method, a ray path is gradually traced and corrected, and the ray path is gradually traced and corrected repeatedly until high imaging precision is obtained by calculation. The a ray tracing type ultrasonic Lamb wave defect tomographic imaging method avoids the problem of low imaging precision of a traditional TOF cross hole tomographic imaging method based on straight ray theory, is accurate, efficient and fast to calculate, provides an important basis for improving the defect imaging precision, and has broad application prospects.

Ray tracing type ultrasonic Lamb wave defect tomographic imaging method

The invention provides a passive wireless temperature measuring system for capacitors of a transformer substation The passive wireless temperature measuring system comprises a passive wireless temperature measuring device, a temperature signal acquisition device and a temperature monitoring device; the passive wireless temperature measuring device is used for detecting temperatures of the capacitors of the transformer substation, receiving excitation signals and converting the excitation signals into resonate temperature acknowledge signals linearly dependent on temperature variation; the temperature signal acquisition device is used for transmitting the excitation signals to the passive wireless temperature measuring device, receiving the temperature acknowledge signals outputted by the passive wireless temperature measuring device, acquiring temperature information according to variation of frequency of the temperature acknowledge signals and outputting the temperature information; and the temperature monitoring device is used for receiving the temperature information outputted by the temperature signal acquisition device and monitoring and processing the temperature information The passive wireless temperature measuring system can overcome the shortcoming of insufficient insulating property in the prior art, does not need an extra power source, is effectively prevented from being affected by environments and surrounding electromagnetic fields, can reliably detect the temperatures of the capacitors under a high-temperature condition for a long time, and does not need to be maintained, so that maintenance cost is reduced, and work efficiency is improved

Passive wireless temperature measuring system for capacitors of transformer substation

A sensor system includes one or more rotor antennas on a shaft that moves within a stator bracket one or more of around an axis of the sensor system or along the axis of the sensor system, the one or more rotor antennas configured to communicate sensed data with one or more stator antennas on the stator bracket. Each rotor antenna has a rotor signal trace disposed on an outer rotor side of a dielectric substrate of the rotor antenna and a rotor return trace disposed on the outer rotor side of the dielectric substrate, wherein the rotor signal trace and the rotor return trace are not concentric with respect to each other. The one or more rotor antennas are configured to extend one or more of radially around an outer surface of the shaft of a sensor or along the outer surface of the shaft of the sensor.

Sensor system and method

The invention discloses a method for detecting internal defects of a cable connector and solves the technical problems in the prior art that a charged partial discharge testing method for detecting internal defects of an intermediate cable connector is not high in detection accuracy and has difficulties in detecting some small defects in the intermediate cable connector. Based on transmission andreflection characteristics of ultrasonic waves, an ultrasonic probe is clung to the outer surface of the cable connector, transmits an ultrasonic signal into the cable connector, and receives a returned ultrasonic reflection signal; and whether a time difference between transmission of the ultrasonic signal and receiving of the returned ultrasonic signal by the ultrasonic prove is consistent witha preset time difference or not is obtained through calculation, so that whether the internal defects exist in the cable connector or not can be judged.

Method for detecting internal defects of cable connector

The invention relates to a high-temperature (600 DEG C) pressure measurement passive wireless surface acoustic wave sensor. The passive wireless high-temperature pressure measurement sensor provided by the invention comprises a piezoelectric substrate material, an interdigital transducer, a reflecting grating, a small size antenna and a high-temperature lead, wherein a single-end surface acoustic wave resonator serves as the core of the high-temperature sensor; the lanthanum gallium silicate serves as the substrate; the interdigital transducer and the reflecting grating are deposited and arranged on the substrate; the surface acoustic wave is aroused and received by utilizing the piezoelectric effect and the inverse piezoelectric effect; the interdigital transducer receives an electromagnetic wave signal from a wireless inquiring unit through the antenna; the surface acoustic wave which is aroused from the surface of the substrate is spread towards two sides and is reflected by the reflecting grating; the reflected surface acoustic wave is reconverted to the electromagnetic wave signal through the interdigital transducer and is transmitted to the wireless inquiring unit through the antenna; and the pressure measurement at a high temperature is realized by using a signal processing method. The pressure sensor is provided with a pressure receiving diaphragm for sensing the pressure. The surface acoustic wave resonator is adhered to the pressure receiving diaphragm by using adhesives and is used for receiving the diaphragm deformation. The sensor has the advantages that the structure is simple, the volume is small, the weight is light, the precision is high, the sensor is wireless and passive, and the sensor is fit for the wireless remote monitoring for high-temperature environmental pressure in aerospace industry, petrochemical industry, nuclear industry, and the like.

High-temperature (600 DEG C) pressure measurement passive wireless surface acoustic wave sensor

The invention relates to an ultrasonic guided wave defect imaging method for impact damages of a carbon fiber composite material. An ellipse positioning imaging algorithm comprehensively utilizing the defect reflection echo signal time and amplitude full wave information based on an ellipse positioning process is provided. The algorithm utilizes an ultrasonic transducer array to obtain defect reflection echo information in different paths, and the signal arrival time and the amplitude information of a signal are accurately extracted by applying complex wavelet transformation, so the imaging of hole defects in a metal plate and a carbon fiber-epoxy resin composite plate is realized. Influences of the sampling interval and the signal-to-noise ratio of the signal allow a CT (computed tomography) algorithm which directly adopts the original signal amplitude to have low precision of the imaging result, so the envelope improved imaging algorithm based on the complex wavelet transformation is introduced in the invention. The envelope improved imaging algorithm can realizes the defect imaging only through six transducers, and the detection precision is improved by applying the complex wavelet transformation, so the accurate quantified detection of impact damage defects of the composite plate is realized.

Ultrasonic guided wave defect imaging method for impact damages of carbon fiber composite material

The invention relates to a surface wave stress sensor based on a three-layer stress transferring model. The surface acoustic wave stress sensor provided by the invention comprises a piezoelectric substrate material, an interdigital transducer, a reverse grid, a small antenna and an adhesive agent used for sticking the sensor, wherein a surface acoustic wave resonator is adhered to a detected object by the adhesive agent. Different from the traditional surface acoustic wave stress sensor, a three-layer mechanical model, namely a detected structure substrate, an adhesive layer, an SAW (surface acoustic wave) resonance layer of the surface acoustic wave stress sensor, is established, a stress transferring formula and a stress transferring coefficient of the SAW sensor are deduced and the factors influencing the SAW sensor measuring result are achieved. The main factors influencing the sensor stress transferring contain the length of the sensor, the thickness of the adhesive layer, the modulus of elasticity, the thickness of an SAW quartz substrate, and the like. The thinner the adhesive layer is, the longer the SAW resonator is and the larger the modulus of elasticity of the material is, the better the detecting precision of the stress sensor is. The surface acoustic wave stress sensor is simple in structure, small in volume, light in weight, convenient to use and suitable for stress wireless remote monitoring under severe environment.

Yuntao Zhang

Papers

High-temperature (600 DEG C) pressure measurement passive wireless surface acoustic wave sensor

Ultrasonic guided wave defect imaging method for impact damages of carbon fiber composite material

Passive wireless surface acoustic wave stress sensor adopting three-layer stress transferring model