Pervasive computing has being now considered and noticed universally, which is the 21st century compute mode. This article first analyzes the origins of generating Mark Weiser's pervasive computing idea and the th...Pervasive computing has being now considered and noticed universally, which is the 21st century compute mode. This article first analyzes the origins of generating Mark Weiser's pervasive computing idea and the thrusts of researching it in the process of computing development. It then simply describes the pervasive computing projects of scientific research organizations of main developed countries, such as enterprise and universities, to realize Mark Weiser's idea. Next, it sketches a Layered Pervasive Computing (LPG) model and its related terms. Finally, the article closes with a discussion of great influence of pervasive computing technologies, and makes prospects of human being living environments such as economic, daily life, work, etc., according to the current development of computer hardware and software technologies and the evolvement of researching pervasive computing.展开更多
For on-line monitoring of welding quality, the characteristics of the arc sound signals in short circuit CO2 GMAW were analyzed in the time and frequency domains. The arc sound presents a series of ringing-like oscill...For on-line monitoring of welding quality, the characteristics of the arc sound signals in short circuit CO2 GMAW were analyzed in the time and frequency domains. The arc sound presents a series of ringing-like oscillations that occur at the end of short circuit i. e. the moment of arc re-ignition, and distributes mainly in the frequency band below 10 kHz. A concept of the arc tone channel and its equivalent electrical model were suggested, which is considered a time-dependent distributed parametric system of which the transmission properties depend upon the geometric and physical characteristics of the arc and surroundings, and is excited by the sound source results from the change of arc energy so that results in arc sound. The linear prediction coding （ LPC ） model is an estimation of the tone channel. The radial basis function （ RBF ） neural networks were built for on-line pattern recognition of the gas-lack in welding, in which the input vectors were formed with the LPC coefficients. The test results proved that the LPC model of arc sound and the RBF networks are feasible in on-line quality monitoring.展开更多
文摘Pervasive computing has being now considered and noticed universally, which is the 21st century compute mode. This article first analyzes the origins of generating Mark Weiser's pervasive computing idea and the thrusts of researching it in the process of computing development. It then simply describes the pervasive computing projects of scientific research organizations of main developed countries, such as enterprise and universities, to realize Mark Weiser's idea. Next, it sketches a Layered Pervasive Computing (LPG) model and its related terms. Finally, the article closes with a discussion of great influence of pervasive computing technologies, and makes prospects of human being living environments such as economic, daily life, work, etc., according to the current development of computer hardware and software technologies and the evolvement of researching pervasive computing.
基金The work was supported by National Natural Science Foundation of China (No. 50275028).
文摘For on-line monitoring of welding quality, the characteristics of the arc sound signals in short circuit CO2 GMAW were analyzed in the time and frequency domains. The arc sound presents a series of ringing-like oscillations that occur at the end of short circuit i. e. the moment of arc re-ignition, and distributes mainly in the frequency band below 10 kHz. A concept of the arc tone channel and its equivalent electrical model were suggested, which is considered a time-dependent distributed parametric system of which the transmission properties depend upon the geometric and physical characteristics of the arc and surroundings, and is excited by the sound source results from the change of arc energy so that results in arc sound. The linear prediction coding （ LPC ） model is an estimation of the tone channel. The radial basis function （ RBF ） neural networks were built for on-line pattern recognition of the gas-lack in welding, in which the input vectors were formed with the LPC coefficients. The test results proved that the LPC model of arc sound and the RBF networks are feasible in on-line quality monitoring.
