Abstract: The present disclosure addresses a system and a method for echo cancellation and signal processing. The method includes configuring an integrated signal processor on an embedded system, wherein the integrated signal processor includes at least an echo canceller and a noise suppressor. The method further includes receiving a reference sound signal transmitted from a client device and capturing, by a microphone of the embedded system, a microphone sound signal to be transmitted to the client device. The method further includes executing the echo canceller to generate a first output signal based on the reference sound signal, the microphone sound signal, and a preliminary echo cancelling coefficient and executing the noise suppressor to generate a second output signal based on the first output signal and a noise estimate. The method further includes transmitting the second output signal to the client device in replacement of the microphone sound signal.

Abstract: The present invention belongs to the field of pharmaceutical and chemical engineering, and relates to a high-purity losartan potassium and a preparation method therefor. The present invention also relates to a high-purity losartan or a pharmaceutically acceptable salt thereof and a preparation method therefor. The present invention uses organic phosphorus to reduce an azide compound to an amino compound so that the genotoxicity of losartan or a pharmaceutically acceptable salt thereof can be well controlled. The method of the present invention involves fewer steps, uses a small amount of reagent, does not require activated carbon decolorization, and produces a high-purity product, and therefore is suitable for industrial production and is very practical.

Abstract: Disclosed in the present invention is a method for preparing high-purity losartan, which belongs to the fields of medicine and chemical engineering. The losartan is obtained by means of a multi-stage temperature reaction in the presence of a catalyst and sodium azide, wherein the temperature in the first stage of the multi-stage temperature reaction is higher than that in the second stage. According to the method, the generation of dimer impurities can be reduced, and the risk of impurities being introduced into a finished losartan potassium product is reduced.

Abstract: A gearbox assembly includes a housing, a cover, a screw rod inserted through the housing along a first direction, a worm wheel integrally formed on the screw rod, and a worm arranged in the housing along a second direction perpendicular to the first direction. The worm is driven into rotation by a driving shaft, so that the worm drives the worm wheel and the screw rod into rotation through a kinetic pair. The screw rod moves a lifting mechanism attached to the screw rod in a vertical direction through screw transmission. A stop pin is arranged on the housing and positioned in the direction of extension of a free end of the driving shaft of the worm against the free end.

Abstract: The present invention relates to a gearbox assembly comprising a housing, a cover, a screw rod that is inserted through said housing along a first direction, a worm wheel integrally formed on said screw rod, and a worm arranged in the housing along a second direction perpendicular to the first direction, said worm being in meshing transmission with the worm wheel, wherein said worm is driven into rotation by a driving shaft, so that the worm drives said worm wheel and said screw rod into rotation through a kinetic pair; said screw rod moves a lifting mechanism attached to the screw rod in a vertical direction through screw transmission; and a stop pin is arranged on said housing, said stop pin being positioned in the direction of extension of a free end of the driving shaft of the worm against the free end. In addition, the present invention further relates to a headrest actuator comprising said gearbox assembly.