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3116 results about "Pulse current" patented technology

Pulsed eddy current infrared thermal imaging detection system and method for steel rail cracks

InactiveCN104764770AConvenient and intuitive detection meansThe energy of the pulse signal is largeMaterial flaws investigationThermodynamicsImage resolution
The invention discloses a pulsed eddy current infrared thermal imaging detection system and method for steel rail cracks. The system comprises an excitation device, an induction heating device, an infrared thermal imager and a PC, wherein the induction heating device is used for generating a pulse current signal; the pulse current signal is exerted to a tested part through the excitation device; eddy current is induced from the surface of the tested part and a thermal effect is generated, so that the surface temperature distribution changes; the infrared thermal imager is used for recording the surface temperature change process of the tested part and transmitting to the PC to process and analyze. The pulsed eddy current infrared thermal imaging detection system is characterized by also comprising a synchronous trigger control circuit, which is used for synchronously controlling the excitation and recording time of the induction heating device and the infrared thermal imager, so that the heating and cooling processes after complete induction of the tested part are accurately recorded; and the condition that the PC obtains accurate data to analyze and treat is ensured. The pulsed eddy current infrared thermal imaging detection system is high in detection efficiency and high in image resolution ratio; excitation of an excitation source and the infrared thermal imager can be synchronously carried out; and the detection result is not affected by human factors.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

Multistage and multidirectional electromagnetic forming method and device

ActiveCN102248059AIncrease forming depthGood moldabilityEddy currentElectromagnetic forming
The invention provides a multistage and multidirectional electromagnetic forming method comprising the following steps of: establishing a stable magnetic field area by adopting quasi-steady state current; generating induced eddy current in a workpiece by using pulse current; driving the part of the workpiece, which is positioned outside a female die, to be deformed away from the direction of the female die by using an electromagnetic force between the induced eddy current and the pulse current and driving the part of the workpiece, which is positioned inside the female die, to be deformed towards the direction close to the female die; and when the part inside the female die is deformed to an area of a stable magnetic field area, driving the workpiece to do accelerated motion to be attached to the female die under the action of induced eddy current in the stable magnetic field and the woprkpiece to finish the forming. The invention also provides a device for realizing the method, mainly comprising an edge pressing ring and coils arranged at different positions of the female die. According to the method and device disclosed by the invention, the workpiece is accelerated in a multistage and multidirectional electromagnetic forming manner, the forming, the processing and the manufacturing in a longer time and larger space range are realized and the forming depth of the workpiece is effectively increased.
Owner:HUAZHONG UNIV OF SCI & TECH

Electromagnetical ultrasonic thickness-measuring method

The invention discloses a method for detecting ferrous magnetic material thickness by utilizing electromagnetic ultrasound, and is characterized in that a magnet inside an electromagnetic ultrasound transducer takes a U-shaped permanent magnet, a coil takes a PCB double-layer coil that takes the shape of a Chinese character, 'Hui' and is positioned at an opening of the permanent magnet, and an effective lead part of the coil is parallel to the direction of a bias magnetic field. In thickness measurement, the electromagnetic ultrasound transducer is positioned on a detected object, high-frequency electric sinusoidal pulse current passes through the coil, according to the magnetostrictive effect, the detected object generates partial stretching deformation and oscillation, and consequently excites ultrasonic transverse wave and leads the ultrasonic transverse wave to spread downwards in a direction vertical to surfaces of the detected object. The ultrasonic wave is reflected by a lower surface of the detected object, and then the reflected wave is received by the coil. A received ultrasonic signal is collected and input into a computer after being amplified. If the ultrasonic wave spreading velocity in the detected object is v, and the spreading time is t, then the thickness of the detected object d is equal to a half of v multiplied by t. The method for detecting ferrous magnetic material thickness by realizing the thickness detection of ferrous magnetic materials, has the non-contact and couplant-free advantages, and can be used in high-temperature environment and for detecting materials with rough surfaces.
Owner:TSINGHUA UNIV

Battery heating method based on battery health status

The invention discloses a battery heating method based on battery health status, and belongs to the technical field of battery heating. The method aims to solve the problem that a battery is incapable of being heated uniformly when the battery is charged and used at a low temperature or that aging of the battery is accelerated due to improper battery low-temperature heating pulse amplitude selection and control caused by the facts that the difference between the charging internal resistance of the battery and the discharging internal resistance of the battery is ignored in the heating process and the influence of the battery health status on battery performance is not taken into account. Alternating-current pulse current is applied to the battery, the battery is heated internally by using the heat generated by the battery internal resistance, the battery internal resistance is finely divided into the charging internal resistance and the discharging internal resistance in the heating process, and the influence of the battery health status on the battery performance is taken into account by using a certain constant polarization voltage as a restricted condition, so that the accuracy of battery low-temperature heating pulse amplitude selection and control is improved, and the influence on the aging of the battery in the heating process of the battery is effectively inhibited.
Owner:HARBIN UNIV OF SCI & TECH
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