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2 results about "Frequency sound" patented technology

In human physiology and psychology, sound is the reception of such waves and their perception by the brain. Humans can only hear sound waves as distinct pitches when the frequency lies between about 20 Hz and 20 kHz. Sound above 20 kHz is ultrasound and is not perceptible by humans.

Low-frequency sound-absorbing polypropylene composition as well as preparation method and application thereof

ActiveCN114479267ALow densityChange dampingElastomerPolymer science
The invention discloses a low-frequency sound-absorbing polypropylene composition as well as a preparation method and application thereof. The low-frequency sound-absorbing polypropylene composition is prepared from the following components in parts by weight: 70 to 85 parts of polypropylene, 10 to 20 parts of elastomer and 5 to 10 parts of talcum powder, the ratio of the 998 cm <-1 > peak area to the 973 cm <-1 > peak area of the polypropylene after annealing at 120 DEG C / 0.5 h is 0.94-0.98; and the molecular weight distribution index of the polypropylene is 2-8. The appropriate PP resin is screened and has a synergistic effect with the elastomer and the talcum powder, so that the damping performance of the polypropylene composition is changed, and the effect of resonance sound absorption can be achieved under the frequency resonance of 200-400 Hz, so that the sound absorption performance of the material is effectively improved, and the noise is reduced.
Owner:TIANJIN KINGFA NEW MATERIAL

Sign-in method and system

InactiveCN112687017ASave check-in timeAchieve intelligenceRegistering/indicating time of eventsElevatorsThe InternetEngineering
The invention provides a sign-in method and system, and the method comprises the steps that: a maintainer arrives at a maintenance site, and opens a maintenance APP of intelligent equipment; the maintenance APP makes a specific frequency sound, and a microphone in a light curtain receives the sound and transmits the sound to an Internet of Things module board card; and the Internet of Things module board card judges whether the specific frequency sound is a preset specific frequency sound, automatically signs in if the specific frequency sound is the preset specific frequency sound, and does not sign in if the specific frequency sound is not the preset specific frequency sound. The maintenance APP is opened, and the light curtain receives the specific frequency sound emitted by the maintenance APP to judge whether the specific frequency sound is the preset specific frequency sound for automatic sign-in, so that the sign-in time of maintenance workers is saved, maintenance work is performed more quickly, and the intelligence of an elevator with the light curtain with the function is embodied.
Sign-in method and system
Sign-in method and system
Sign-in method and system
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Owner:MOCHITEC SHANGHAI CO LTD

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Polypropylene Polymer chemistry Human–computer interaction Internet of Things Microphone
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