Abstract: Discloses are a loudspeaker and an audio system. The loudspeaker includes a frame, a diaphragm for vibrating to produce sound and arranged on the frame, a voice coil for driving the diaphragm to vibrate, a magnetic circuit for driving the voice coil to vibrate, and an annular member arranged at an upper end portion of the voice coil and connected to the diaphragm. The magnetic circuit is arranged on the frame, and the magnetic circuit is provided with a magnetic gap for a lower end portion of the voice coil to insert in. The loudspeaker can achieve more prominent low frequency at a low cost during working, without overlap of frequency response when working together with a tweeter.

Abstract: A surgical robot, a method for guiding a surgical arm to move, and a computer readable storage medium thereof. The method includes: acquiring an original position of the operation end effector; determining a target position where the operation end effector is expected to reach; generating a guiding path extended from the original position to the target position according to a vision field of the image end effector; adjusting the operation end effector to move along the guiding path from the original position to the target position. The surgical robot can ensure a safety and a reliability of a surgery.

Abstract: The present invention discloses compounds of Formula (I), and pharmaceutically acceptable salts, thereof: which inhibit coronavirus replication activity. The invention further relates to pharmaceutical compositions comprising a compound of Formula (I) or a pharmaceutically acceptable salt thereof, and methods of treating or preventing a coronavirus infection in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a compound of Formula (I) or a pharmaceutically acceptable salt thereof.

Abstract: A continuous asphalt mixture production plant based on double-horizontal-shaft forced mixing includes a cold aggregate bin, a continuous aggregate conveying and metering system, a drying drum, an aggregate elevator, a double-horizontal-shaft continuous mixing host, a continuous asphalt metering and conveying system, a continuous powder conveying and metering system and a finished product bin. The double-horizontal-shaft continuous mixing host includes a first double-horizontal-shaft mixing cylinder and a second double-horizontal-shaft mixing cylinder connected in series. The first double-horizontal-shaft mixing cylinder is provided with an aggregate inlet, an asphalt inlet, a powder inlet and a first discharging port, and the second double-horizontal-shaft mixing cylinder is provided with a mixture inlet and a second discharging port.

Abstract: A continuous asphalt mixture production plant based on double-horizontal-shaft forced mixing includes a cold aggregate bin, a continuous aggregate conveying and metering system, a drying drum, an aggregate elevator, a double-horizontal-shaft continuous mixing host, a continuous asphalt metering and conveying system, a continuous powder conveying and metering system and a finished product bin. The double-horizontal-shaft continuous mixing host includes a first double-horizontal-shaft mixing cylinder and a second double-horizontal-shaft mixing cylinder connected in series. The first double-horizontal-shaft mixing cylinder is provided with an aggregate inlet, an asphalt inlet, a powder inlet and a first discharging port, and the second double-horizontal-shaft mixing cylinder is provided with a mixture inlet and a second discharging port.

Abstract: The present invention relates to a process for preparing a bio-diesel, comprising the steps of, in the presence of an additional free fatty acid source, reacting a raw oil-fat with C1-C6 monohydric alcohol in a reactor, and separating fatty acid esters from the reacted materials, so as to produce the bio-diesel, wherein the amount of the free fatty acid in the free fatty acid source ranges from 2-100 wt % and is higher than the amount of the free fatty acid in the raw fat-oil. The present process can increase the fatty acid ester yield and purity of raw oil-fats having a low reaction activity, and has a high adaptability to raw materials.

Abstract: The present invention provides a process for preparing a bio-diesel, comprising, in the presence of an alkaline metal compound, reacting an oil-fat with C1-C6 monohydric alcohol in a reactor at a reaction temperature of from 130 to 280° C. and a reaction pressure of from 1 to 12 MPa, separating fatty acid esters from the reacted materials, so as to produce the bio-diesel, wherein said alkaline metal compound is present in an amount of 0.001-0.07 wt %, in terms of the metal thereof, relative to the weight of the oil-fat. The process provided in the present invention has the advantages of great throughput and high yield of the bio-diesel.

Abstract: The present invention provides a process for preparing a bio-diesel, comprising, in the presence of an alkaline metal compound, reacting an oil-fat with C1-C6 monohydric alcohol in a reactor at a reaction temperature of from 130 to 280° C. and a reaction pressure of from 1 to 12 MPa, separating fatty acid esters from the reacted materials, so as to produce the bio-diesel, wherein said alkaline metal compound is present in an amount of 0.001-0.07 wt %, in terms of the metal thereof, relative to the weight of the oil-fat. The process provided in the present invention has the advantages of great throughput and high yield of the bio-diesel.

Abstract: The present invention relates to a process for preparing a bio-diesel, comprising the steps of, in the presence of an additional free fatty acid source, reacting a raw oil-fat with C1-C6 monohydric alcohol in a reactor, and separating fatty acid esters from the reacted materials, so as to produce the bio-diesel, wherein the amount of the free fatty acid in the free fatty acid source ranges from 2-100 wt % and is higher than the amount of the free fatty acid in the raw fat-oil. The present process can increase the fatty acid ester yield and purity of raw oil-fats having a low reaction activity, and has a high adaptability to raw materials.

Abstract: A process for vapor phase hydrogenation of maleic anhydride and/or succinic anhydride to .gamma.-butyrolactone, comprising contacting an alcoholic solution of a feedstock anhydride with reduced Cu-Zn-Cr-Zr catalyst under the conditions of hydrogenation.