As the earliest invented and utilized communication approach, shortwave, known as high frequency(HF) communication now experience the deterioration of HF electromagnetic environment. Finding quality frequency in effic...As the earliest invented and utilized communication approach, shortwave, known as high frequency(HF) communication now experience the deterioration of HF electromagnetic environment. Finding quality frequency in efficient manner becomes one of the key challenges in HF communication. Spectrum prediction infers the future spectrum status from history spectrum data by exploring the inherent correlations and regularities. The investigation of HF electromagnetic environment data reveals the correlations and predictability of HF frequency band in both time and frequency domain. To solve this problem, we develop a Spectrum Prediction-based Frequency Band Pre-selection(SP-FBP) for HF communications. The pre-selection of HF frequency band mainly incorporated in prediction of HF spectrum occupancy and prediction of HF usable frequency, which provide the frequency band ranking of spectrum occupancy and alternative frequency for spectrum sensing, respectively. Performance evaluation via real-world HF spectrum data shows that SP-FBP significantly improves the efficiency of finding quality frequency in HF communications.展开更多
The interacting boson model for anomalous rotational bands is proposed. In the rotational SU(3) limit,an asymptotic limit is discussed. Within the framework of the model several analytic relations for energies and ele...The interacting boson model for anomalous rotational bands is proposed. In the rotational SU(3) limit,an asymptotic limit is discussed. Within the framework of the model several analytic relations for energies and electro-magnetic transition rates are derived.展开更多
Within the framework of the Usdpf(16) interacting boson model (IBM), the effects of strong correlations of the dipole (p--boson) and the octupole (f--boson) degree of freedom on the positive-parity states of even-even...Within the framework of the Usdpf(16) interacting boson model (IBM), the effects of strong correlations of the dipole (p--boson) and the octupole (f--boson) degree of freedom on the positive-parity states of even-even nuclei in SU(3) limit are discussed. It is shown that configurations of an even number of many p- and f-bosons can not only be incorporated into the usual low-lying collective rotational bands, such as the ground state band, β- and γ-vibrational bands, but also naturally form the Kπ＝ 1+, 3+ rotational bands, etc. These results are similar to that of Usdg (15)-IBM and in agreement well with the experimental data of the 176 72 Hf 104 nucleus. Besides, several intraband E2 transition probabilities are given, which are consistent with that of Usd(6)-IBM.展开更多
基金the Project of National Natural Science Foundation of China (Grant No. 61471395, No. 61301161, and No. 61501510)partly supported by Natural Science Foundation of Jiangsu Province (Grant No. BK20161125 and No. BK20150717)
文摘As the earliest invented and utilized communication approach, shortwave, known as high frequency(HF) communication now experience the deterioration of HF electromagnetic environment. Finding quality frequency in efficient manner becomes one of the key challenges in HF communication. Spectrum prediction infers the future spectrum status from history spectrum data by exploring the inherent correlations and regularities. The investigation of HF electromagnetic environment data reveals the correlations and predictability of HF frequency band in both time and frequency domain. To solve this problem, we develop a Spectrum Prediction-based Frequency Band Pre-selection(SP-FBP) for HF communications. The pre-selection of HF frequency band mainly incorporated in prediction of HF spectrum occupancy and prediction of HF usable frequency, which provide the frequency band ranking of spectrum occupancy and alternative frequency for spectrum sensing, respectively. Performance evaluation via real-world HF spectrum data shows that SP-FBP significantly improves the efficiency of finding quality frequency in HF communications.
基金supported by National Natural Science Foundation of China under Grant No. 10475026the Natural Science Foundation of Zhejiang Province under Grant No. KY607518
文摘The interacting boson model for anomalous rotational bands is proposed. In the rotational SU(3) limit,an asymptotic limit is discussed. Within the framework of the model several analytic relations for energies and electro-magnetic transition rates are derived.
文摘Within the framework of the Usdpf(16) interacting boson model (IBM), the effects of strong correlations of the dipole (p--boson) and the octupole (f--boson) degree of freedom on the positive-parity states of even-even nuclei in SU(3) limit are discussed. It is shown that configurations of an even number of many p- and f-bosons can not only be incorporated into the usual low-lying collective rotational bands, such as the ground state band, β- and γ-vibrational bands, but also naturally form the Kπ＝ 1+, 3+ rotational bands, etc. These results are similar to that of Usdg (15)-IBM and in agreement well with the experimental data of the 176 72 Hf 104 nucleus. Besides, several intraband E2 transition probabilities are given, which are consistent with that of Usd(6)-IBM.
