Abstract: The present invention provides a die capable of achieving rapid forming and quenching therein. The die includes an upper die, a blank holder and a lower die, where the upper die is composed of an internal solid die core and a thin-walled skin. Grooves in communication with each other are disposed between the internal solid die core and the thin-walled skin. In a forming stage, the grooves are not filled or filled with a heat insulating material such as a gas; and in a quenching stage, a low-temperature medium is introduced into the grooves. The die can be used to achieve rapid forming and quenching of metal materials of different types and thicknesses.

Abstract: A method and system for eliminating echo in a speaker-microphone communication system are provided.

Abstract: A method and system for eliminating echo in a speaker-microphone communication system are provided.

Abstract: A propelling pencil has a writing core which can be fed out and drawn back controllably and freely. The front portion of the propelling pencil is inserted in the lower end of the shaft of the propelling pencil. The inner surface of the shaft has several ridges which together act as longitudinal guides for the writing core holder. A helical wire, controlling the core holder movement, is formed by winding a flat metal wire. The core holder is made of an elastic material and has a hole therein which has a large diameter at each end thereof and a relatively small diameter at its central region. The core holder is also provided with longitudinal ridges in its lower portion to prevent rotation of the writing core held therein.