摘要:
A supercritical carbon dioxide-assisted solid-phase grafting modification method for polypropylene, comprises swelling polypropylene for 0.5 to 10 hours in supercritical carbon dioxide having dissolved vinyl monomer and an initiator, then slowly relieving the pressure; moving the polypropylene that has undergone the swelling process into a reaction kettle, and adding xylene as an interface agent, the mass of xylene being 1% of the polypropylene; increasing the temperature to between 65° C. and 165° C. under normal pressure, and reacting 1 to 10 hours to obtain modified polypropylene; the swelling permeation temperature during the swelling process is from 31° C. to 60° C., the swelling pressure is from 7.5 to 12 MPa; the initiator is an azo compound or a peroxide. In the present method, the grafting rate reaches 5.4%, the thermal property, polarity, and mechanical property all improve substantially, and hydrophilic property is substantially enhanced.
摘要:
A speech encoding method using analysis-by-synthesis includes sampling an input speech and dividing the resulting speech samples into frames and subframes. The frames are analyzed to determine coefficients for the synthesis filter. The subframes are categorized into unvoiced, voiced and onset categories. Based on the category, a different coding scheme is used. The coded speech is fed into the synthesis filter, the output of which is compared to the input speech samples to produce an error signal. The coding is then adjusted per the error signal.