3results about How to "Lower cutoff frequency" patented technology

The application provides a non-contact ECG signal collection foot ring sensor, which comprises a foot ring body and an ECG signal sensor arranged on the foot ring body, wherein the ECG signal sensor comprises an electrode composite layer, a first insulating layer, an electromagnetic shielding layer and a second insulating layer arranged in sequence, the electrode composite layer comprises a first electrode, a second electrode and a polarity layer arranged between the first electrode and the second electrode, the polarity layer comprises a polarity material of barium titanate and / or calcium titanate, the first electrode is used for being connected to an ECG collection circuit, the second electrode is arranged in suspension, and the electromagnetic shielding layer is grounded. The foot ring sensor of the application comprises the electrode composite layer, the electrode composite layer contains the polarity material of barium titanate and / or calcium titanate with high dielectric constant, and thus has high dielectric performance, can effectively improve the coupling capacitance between the skin and the electrode, and further reduce the capacitive reactance and total impedance, reduce the attenuation degree of the ECG signal in the coupling process, and improve the electric signal detection effect.

The invention discloses a negative group delay SSPP transmission circuit based on a PSO algorithm and an optimization method thereof, and belongs to the technical field of microwave engineering, the circuit comprises a dielectric substrate and a negative group delay SSPP transmission module arranged on at least one surface of the dielectric substrate; the negative group delay SSPP transmission module comprises an SSPP transmission line and a circuit structure; the SSPP transmission line forms an SSPP transmission section through a plurality of pixelated SSPP main body units which are periodically etched on the surface of the dielectric substrate along the signal propagation direction; the circuit structure comprises pixelated circuit units etched in gaps of adjacent pixelated SSPP main body units, and the pixelated circuit units are used for generating negative group delay. Pixel value distribution of the pixelated SSPP main body unit and pixel value distribution of the pixelated circuit unit are obtained through PSO algorithm optimization, and optimization targets comprise minimum cut-off frequency and minimum negative group delay, so that the SSPP transmission circuit generates negative group delay characteristics, and the cut-off frequency is reduced.

This invention discloses an array-type acoustic black hole ring vibrator and a broadband vibration absorption device for pipelines including the array-type acoustic black hole ring vibrator, belonging to the technical field of vibration reduction devices. The array-type acoustic black hole ring vibrator of this invention is fixed to the outside of an annular pipeline and includes several acoustic black hole structural units arranged in an array along the circumference of the annular pipeline. The distances between the outer and inner surfaces of each acoustic black hole structural unit and the radial central axis of the annular pipeline exhibit a smooth gradient change with a periodic variation, being larger at both ends and smaller at the center, forming an outer arc-shaped profile surface and an inner arc-shaped profile surface. A ring segment of constant thickness is also provided between every two acoustic black hole structural units. This invention can achieve lower frequency and wider frequency pipeline vibration suppression without changing the internal flow channel structure of the pipeline or causing any damage to the pipeline.