An analytical solution is presented for the electromagnetic scattering from an infinite-length metallic carbon nanotube and a carbon nanotube bundle. The scattering field and scattering cross section are predicted usi...An analytical solution is presented for the electromagnetic scattering from an infinite-length metallic carbon nanotube and a carbon nanotube bundle. The scattering field and scattering cross section are predicted using a modal technique based on a Bessel and Hankel function for the electric line source and a quantum conductance function for the carbon nanotube. For the particular case of an isolated armchair （10, 10） carbon nanotube, the scattered field predicted from this technique is in excellent agreement with the measured result. Furthermore, the analysis indicates that the scattering pattern of an isolated carbon nanotube differs from that of the carbon nanotube bundle of identical index （m, n） metallic carbon nanotubes.展开更多
This paper investigates the radiation characteristics of metal single-walled zig-zag carbon nanotubes as a dipole antenna at terahertz wave range. The current distribution, input impedance and mutual impedance are cal...This paper investigates the radiation characteristics of metal single-walled zig-zag carbon nanotubes as a dipole antenna at terahertz wave range. The current distribution, input impedance and mutual impedance are calculated for various geometrical parameters of vertically-aligned carbon nanotubes. The numerical results demonstrate the properties of the antenna depending strongly on the geometrical parameters such as the radius, the lengths of carbon nantobues, and the spacing between nanotubes. It is found that the zig-zag carbon nanotubes exhibit very high input impedance and the mutual impedances for antenna array applications. These unique high impedance properties are different from the conventional metal thin wire antenna. The far-field patterns and gain of antenna array are also calculated. The maximum gain of array of 100-element array is up to 20.0 dB, which is larger than the gain of 0.598 dB of single dipole antenna at distance d = 0.5λ.展开更多
Collecting massive commonsense knowledge （CSK） for commonsense reasoning has been a long time standing challenge within artificial intelligence research. Numerous methods and systems for acquiring CSK have been deve...Collecting massive commonsense knowledge （CSK） for commonsense reasoning has been a long time standing challenge within artificial intelligence research. Numerous methods and systems for acquiring CSK have been developed to overcome the knowledge acquisition bottleneck. Although some specific commonsense reasoning tasks have been presented to allow researchers to measure and compare the performance of their CSK systems, we compare them at a higher level from the following aspects： CSK acquisition task （what CSK is acquired from where）, technique used （how can CSK be acquired）, and CSK evaluation methods （how to evaluate the acquired CSK）. In this survey, we first present a categorization of CSK acquisition systems and the great challenges in the field. Then, we review and compare the CSK acquisition systems in detail. Finally, we conclude the current progress in this field and explore some promising future research issues.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60871073,60971064,and 51005001)the Open Program of the State Key Laboratory of Millimeter Wave of China(Grant No.K201006)+1 种基金the Special Funds for the Technological and Innovative Talent of Harbin City,China(Grant No.2010RFXXG010)the Youth Foundation of Harbin University of Science and Technology,China(Grant Nos.2009YF025 and 2009YF024)
文摘An analytical solution is presented for the electromagnetic scattering from an infinite-length metallic carbon nanotube and a carbon nanotube bundle. The scattering field and scattering cross section are predicted using a modal technique based on a Bessel and Hankel function for the electric line source and a quantum conductance function for the carbon nanotube. For the particular case of an isolated armchair （10, 10） carbon nanotube, the scattered field predicted from this technique is in excellent agreement with the measured result. Furthermore, the analysis indicates that the scattering pattern of an isolated carbon nanotube differs from that of the carbon nanotube bundle of identical index （m, n） metallic carbon nanotubes.
基金Project supported by the National Natural Science Foundation of China (Grant No.60571026)the Open Project of State Key Laboratory of Millimeter Wave (Grant No.K201006)the Science and Technology Research Foundation of Heilongjiang Education Bureau of China (Grant No.11531055)
文摘This paper investigates the radiation characteristics of metal single-walled zig-zag carbon nanotubes as a dipole antenna at terahertz wave range. The current distribution, input impedance and mutual impedance are calculated for various geometrical parameters of vertically-aligned carbon nanotubes. The numerical results demonstrate the properties of the antenna depending strongly on the geometrical parameters such as the radius, the lengths of carbon nantobues, and the spacing between nanotubes. It is found that the zig-zag carbon nanotubes exhibit very high input impedance and the mutual impedances for antenna array applications. These unique high impedance properties are different from the conventional metal thin wire antenna. The far-field patterns and gain of antenna array are also calculated. The maximum gain of array of 100-element array is up to 20.0 dB, which is larger than the gain of 0.598 dB of single dipole antenna at distance d = 0.5λ.
基金supported by the National Natural Science Foundation of China under Grant Nos.91224006,61173063,61035004,61203284,and 309737163the National Social Science Foundation of China under Grant No.10AYY003
文摘Collecting massive commonsense knowledge （CSK） for commonsense reasoning has been a long time standing challenge within artificial intelligence research. Numerous methods and systems for acquiring CSK have been developed to overcome the knowledge acquisition bottleneck. Although some specific commonsense reasoning tasks have been presented to allow researchers to measure and compare the performance of their CSK systems, we compare them at a higher level from the following aspects： CSK acquisition task （what CSK is acquired from where）, technique used （how can CSK be acquired）, and CSK evaluation methods （how to evaluate the acquired CSK）. In this survey, we first present a categorization of CSK acquisition systems and the great challenges in the field. Then, we review and compare the CSK acquisition systems in detail. Finally, we conclude the current progress in this field and explore some promising future research issues.
