The signal excited by the airgun source is weak,and is easily affected by human motion noise,instrument failure,and earthquake and blasting events,resulting in insufficient utilization of the amplitude information of ...The signal excited by the airgun source is weak,and is easily affected by human motion noise,instrument failure,and earthquake and blasting events,resulting in insufficient utilization of the amplitude information of the airgun signal.The effective removal of interference and the preservation of true amplitude information of the signal is difficult in airgun signal processing.Based on the randomness of noise and the highly repetitive characteristics of airgun signals,we propose probability data screening method.The airgun data from experiments conducted in the Ansha Reservoir and Shanmei Reservoir in Fujian Province in June,2017 are taken as the research object to assess the effect in practical applications.The results show that the probability data screening method can automatically reject multiple interferences and effectively preserve the amplitude information of the signal by screening out large amplitude records in appropriate proportions.Compared with direct linear superposition,the probability-related linear superposition method can effectively reduce the impact of abnormal interference,and significantly improve the quality of the observed data.展开更多
Recently,the increasing demand of radio spectrum for the next generation communication systems due to the explosive growth of applications appetite for bandwidths has led to the problem of spectrum scarcity.The potent...Recently,the increasing demand of radio spectrum for the next generation communication systems due to the explosive growth of applications appetite for bandwidths has led to the problem of spectrum scarcity.The potential approaches among the proposed solutions to resolve this issue are well explored cognitive radio(CR)technology and recently introduced non-orthogonal multiple access(NOMA)techniques.Both the techniques are employed for efficient spectrum utilization and assure the significant improvement in the spectral efficiency.Further,the significant improvement in spectral efficiency can be achieved by combining both the techniques.Since the CR is well-explored technique as compared to that of the NOMA in the field of communication,therefore it is worth and wise to implement this technique over the CR.In this article,we have presented the frameworks of NOMA implementation over CR as well as the feasibility of proposed frameworks.Further,the differences between proposed CR-NOMA and conventional CR frameworks are discussed.Finally,the potential issues regarding the implementation of CR-NOMA are explored.展开更多
Apart from usual quantization steps on the ballistic conductance of quasi-one-dimensional conductor, an additional plateau-like feature appears at a fraction of about 0.7 below the first conductance step in GaAs-based...Apart from usual quantization steps on the ballistic conductance of quasi-one-dimensional conductor, an additional plateau-like feature appears at a fraction of about 0.7 below the first conductance step in GaAs-based quantum point contacts (QPCs). Despite a tremendous amount of research on this anomalous feature, its origin remains still unclear. Here, a unique model of this anomaly is proposed relying on fundamental principles of quantum mechanics. It is noticed that just after opening a quasi-1D conducting channel in the QPC a single electron travels the channel at a time, and such electron can be—in principle—observed. The act of observation destroys superposition of spin states, in which the electron otherwise exists, and this suppresses their quantum interference. It is shown that then the QPC-conductance is reduced by a factor of 0.74. “Visibility” of electron is enhanced if the electron spends some time in the channel due to resonant transmission. Electron’s resonance can also explain an unusual temperature behavior of the anomaly as well as its recently discovered feature: oscillatory modulation as a function of the channel length and electrostatic potential. A recipe for experimental verification of the model is given.展开更多
基金Joint Funding by the National Natural Science Foundation of China(41774068)the National Natural Science Foundation of China(41790461)
文摘The signal excited by the airgun source is weak,and is easily affected by human motion noise,instrument failure,and earthquake and blasting events,resulting in insufficient utilization of the amplitude information of the airgun signal.The effective removal of interference and the preservation of true amplitude information of the signal is difficult in airgun signal processing.Based on the randomness of noise and the highly repetitive characteristics of airgun signals,we propose probability data screening method.The airgun data from experiments conducted in the Ansha Reservoir and Shanmei Reservoir in Fujian Province in June,2017 are taken as the research object to assess the effect in practical applications.The results show that the probability data screening method can automatically reject multiple interferences and effectively preserve the amplitude information of the signal by screening out large amplitude records in appropriate proportions.Compared with direct linear superposition,the probability-related linear superposition method can effectively reduce the impact of abnormal interference,and significantly improve the quality of the observed data.
文摘Recently,the increasing demand of radio spectrum for the next generation communication systems due to the explosive growth of applications appetite for bandwidths has led to the problem of spectrum scarcity.The potential approaches among the proposed solutions to resolve this issue are well explored cognitive radio(CR)technology and recently introduced non-orthogonal multiple access(NOMA)techniques.Both the techniques are employed for efficient spectrum utilization and assure the significant improvement in the spectral efficiency.Further,the significant improvement in spectral efficiency can be achieved by combining both the techniques.Since the CR is well-explored technique as compared to that of the NOMA in the field of communication,therefore it is worth and wise to implement this technique over the CR.In this article,we have presented the frameworks of NOMA implementation over CR as well as the feasibility of proposed frameworks.Further,the differences between proposed CR-NOMA and conventional CR frameworks are discussed.Finally,the potential issues regarding the implementation of CR-NOMA are explored.
文摘Apart from usual quantization steps on the ballistic conductance of quasi-one-dimensional conductor, an additional plateau-like feature appears at a fraction of about 0.7 below the first conductance step in GaAs-based quantum point contacts (QPCs). Despite a tremendous amount of research on this anomalous feature, its origin remains still unclear. Here, a unique model of this anomaly is proposed relying on fundamental principles of quantum mechanics. It is noticed that just after opening a quasi-1D conducting channel in the QPC a single electron travels the channel at a time, and such electron can be—in principle—observed. The act of observation destroys superposition of spin states, in which the electron otherwise exists, and this suppresses their quantum interference. It is shown that then the QPC-conductance is reduced by a factor of 0.74. “Visibility” of electron is enhanced if the electron spends some time in the channel due to resonant transmission. Electron’s resonance can also explain an unusual temperature behavior of the anomaly as well as its recently discovered feature: oscillatory modulation as a function of the channel length and electrostatic potential. A recipe for experimental verification of the model is given.
