This paper studies pinning-controlled synchronization of complex networks with bounded or unbounded synchronized regions. To study a state-feedback pinning-controlled network with N nodes, it first converts the contro...This paper studies pinning-controlled synchronization of complex networks with bounded or unbounded synchronized regions. To study a state-feedback pinning-controlled network with N nodes, it first converts the controlled network to an extended network of N＋1 nodes without controls. It is shown that the controlled synchronizability of the given network is determined by the real part of the smallest nonzero eigenvalue of the coupling matrix of its extended network when the synchronized region is unbounded; but it is determined by the ratio of the real parts of the largest and the smallest nonzero eigenvalues of the coupling matrix when the synchronized region is bounded. Both theoretical analysis and numerical simulation show that the portion of controlled nodes has no critical values when the synchronized region is unbounded, but it has a critical value when the synchronized region is bounded. In the former case, therefore, it is possible to control the network to achieve synchronization by pinning only one node. In the latter case, the network can achieve controlled synchronization only when the portion of controlled nodes is larger than the critical value.展开更多
Since the 20 thcentury,the time intervals of M ≥6.7 strong earthquakes in the SichuanYunnan region show obvious regularity.Using the years of the strong events,a twodimensional time coordinate system is generated,bas...Since the 20 thcentury,the time intervals of M ≥6.7 strong earthquakes in the SichuanYunnan region show obvious regularity.Using the years of the strong events,a twodimensional time coordinate system is generated,based on which,the time prediction model is constructed for strong earthquakes in the Sichuan-Yunnan region.Prediction analysis shows that there is risk of generating four earthquakes with M ≥ 6.7 in the Sichuan-Yunnan region in the future 16 years,and there are strong signals for M ≥6.7earthquakes for periods 2012-2021 and 2025-2029.The strong earthquakes may occur around 2014-2015,2019 and 2027.展开更多
In this article, we propose a novel, multilevel, dynamic factor model, to determine endogenously clustered regions for the investigation of regional clustering and synchronization of provincial business fluctuations i...In this article, we propose a novel, multilevel, dynamic factor model, to determine endogenously clustered regions for the investigation of regional clustering and synchronization of provincial business fluctuations in China. The parameter identification and model estimation was conducted using the Markov Chain Monte Carlo method. We then conducted an empirical study of the provincial business fluctuations in China(31 Chinese provinces are considered except Hong Kong, Macao, and Taiwan due to the data unavailability), which were sampled from January 2000 to December 2015. Our results indicated that these provinces could be clustered into four regions: leading, coincident, lagging, and overshooting. In comparison with traditional geographical divisions, this novel clustering into four regions enabled the regional business cycle synchronization to be more accurately captured. Within the four regional clusters it was possible to identify substantial heterogeneities among regional business cycle fluctuations, especially during the periods of the 2008 financial crisis and the ‘four-trillion economic stimulus plan'.展开更多
The digital communication of two-dimensional messages is investigated when two solid state multi-mode chaotic lasers are employed in a master-slave configuration. By introducing the time derivative of intensity differ...The digital communication of two-dimensional messages is investigated when two solid state multi-mode chaotic lasers are employed in a master-slave configuration. By introducing the time derivative of intensity difference between the receiver （carrier） and the transmittal （carrier plus signal）, several signals can be encoded into a single pulse. If one signal contains several binary bits, two-dimensional messages in the form of a matrix can be encoded and transmitted on a single pulse. With these improvements in secure communications using chaotic multi-mode lasers, not only the transmission rate can be increased but also the privacy can be enhanced greatly.展开更多
In the study of complex networks, it is commonly believed that the eigenratio λ2/λN of the Laplacian matrix of a network represents the network synchronizability, especially for symmetric networks. This paper gives ...In the study of complex networks, it is commonly believed that the eigenratio λ2/λN of the Laplacian matrix of a network represents the network synchronizability, especially for symmetric networks. This paper gives two counterexamples to show that this is not true for the case where the network has a disconnected synchronized region. Consequently, a simple answer is presented to the question of when the eigenratio λ2/λN does represent the network synchronizability.展开更多
Anorectal melanoma is a very rare tumor with poor prognosis. Rectal bleeding is the most frequent symptom and surgical treatment ranges from local excision to radical abdominoperineal resection. We report a case of a ...Anorectal melanoma is a very rare tumor with poor prognosis. Rectal bleeding is the most frequent symptom and surgical treatment ranges from local excision to radical abdominoperineal resection. We report a case of a 75-years-old male patient who presented with a history of recurrent rectal bleeding, and whose histopathological diagnosis was melanoma. Macroscopically, we found two distinct tumors in anorectal region, 0.5 cm and 1.5 cm from dentate line. The first one was pedunculated, on a thin stalk, measuring 1 cm in greatest diameter, and the second one was sessile and nodular measuring up to 2.8 cm in largest diameter. Microscopic examination and immunohistochemical analysis of both tumors confirmed the diagnosis of melanoma. This case represents multiple synchronous primary melanoma of the anorectal region, with a possibility that one of the lesions is primary melanoma and the second one is a satellite lesion.展开更多
The primary results have been obtained by the analyses on the deviation of macroscopic epicenters from relevant microscopic epicenters determined rapidly after the 139 earthquake events occunrred during 1989-2004. Fur...The primary results have been obtained by the analyses on the deviation of macroscopic epicenters from relevant microscopic epicenters determined rapidly after the 139 earthquake events occunrred during 1989-2004. Further study has proved the normal distributions exist in both the east and west parts of Chinese mainland partitioned along meridian 105°E. The empirical two-dimensional normal distribution functions for the deviations are presented in the paper. The results are of significance in reducing uncertainty of losses assessment immediately after a destroyed earthquake.展开更多
针对弱连接条件下锁相环同步电压源变流器WG-VSC(weak grid connected voltage source converter)系统的暂态同步稳定问题,首先建立了适用于分析WG-VSC系统在严重电网故障期间的锁相环同步暂态稳定问题的等效转子摇摆方程模型。然后利...针对弱连接条件下锁相环同步电压源变流器WG-VSC(weak grid connected voltage source converter)系统的暂态同步稳定问题,首先建立了适用于分析WG-VSC系统在严重电网故障期间的锁相环同步暂态稳定问题的等效转子摇摆方程模型。然后利用改进的等面积定则I-EAC(improved equal area criterion)揭示了弱连接条件下VSC并网系统在严重电网故障下的暂态同步失稳机理;在此基础上,给出了系统在严重电网故障等大扰动下的保证系统暂态稳定的注入电流暂态稳定域的解析边界,为故障期间注入电流策略的制定提供了理论依据。最后,在PSCAD/EMTDC搭建了WG-VSC系统的详细开关模型,仿真结果验证了等效转子摇摆方程模型以及注入电流稳定域的有效性。展开更多
基金supported by the National Natural Science Foundation of China (Grant No 10647001)the Guangxi Natural Science Foundation (Grant No 0728042)+1 种基金the Program for Excellent Talents in Guangxi Higher Education Institutions (Grant No RC2007006)the NSFC-HK Joint Research Scheme (Grant No N-CityU107/07)
文摘This paper studies pinning-controlled synchronization of complex networks with bounded or unbounded synchronized regions. To study a state-feedback pinning-controlled network with N nodes, it first converts the controlled network to an extended network of N＋1 nodes without controls. It is shown that the controlled synchronizability of the given network is determined by the real part of the smallest nonzero eigenvalue of the coupling matrix of its extended network when the synchronized region is unbounded; but it is determined by the ratio of the real parts of the largest and the smallest nonzero eigenvalues of the coupling matrix when the synchronized region is bounded. Both theoretical analysis and numerical simulation show that the portion of controlled nodes has no critical values when the synchronized region is unbounded, but it has a critical value when the synchronized region is bounded. In the former case, therefore, it is possible to control the network to achieve synchronization by pinning only one node. In the latter case, the network can achieve controlled synchronization only when the portion of controlled nodes is larger than the critical value.
文摘Since the 20 thcentury,the time intervals of M ≥6.7 strong earthquakes in the SichuanYunnan region show obvious regularity.Using the years of the strong events,a twodimensional time coordinate system is generated,based on which,the time prediction model is constructed for strong earthquakes in the Sichuan-Yunnan region.Prediction analysis shows that there is risk of generating four earthquakes with M ≥ 6.7 in the Sichuan-Yunnan region in the future 16 years,and there are strong signals for M ≥6.7earthquakes for periods 2012-2021 and 2025-2029.The strong earthquakes may occur around 2014-2015,2019 and 2027.
基金Under the auspices of the National Natural Science Foundation of China(No.71371160)the Program for Changjiang Youth Scholars(No.Q2016131)the Program for New Century Excellent Talents in University(No.NCET-13-0509)
文摘In this article, we propose a novel, multilevel, dynamic factor model, to determine endogenously clustered regions for the investigation of regional clustering and synchronization of provincial business fluctuations in China. The parameter identification and model estimation was conducted using the Markov Chain Monte Carlo method. We then conducted an empirical study of the provincial business fluctuations in China(31 Chinese provinces are considered except Hong Kong, Macao, and Taiwan due to the data unavailability), which were sampled from January 2000 to December 2015. Our results indicated that these provinces could be clustered into four regions: leading, coincident, lagging, and overshooting. In comparison with traditional geographical divisions, this novel clustering into four regions enabled the regional business cycle synchronization to be more accurately captured. Within the four regional clusters it was possible to identify substantial heterogeneities among regional business cycle fluctuations, especially during the periods of the 2008 financial crisis and the ‘four-trillion economic stimulus plan'.
基金Project supported by the Natural Science Foundation of Jiangsu Province, China （Grant No BK2001138）.
文摘The digital communication of two-dimensional messages is investigated when two solid state multi-mode chaotic lasers are employed in a master-slave configuration. By introducing the time derivative of intensity difference between the receiver （carrier） and the transmittal （carrier plus signal）, several signals can be encoded into a single pulse. If one signal contains several binary bits, two-dimensional messages in the form of a matrix can be encoded and transmitted on a single pulse. With these improvements in secure communications using chaotic multi-mode lasers, not only the transmission rate can be increased but also the privacy can be enhanced greatly.
基金Project supported by the National Natural Science Foundation of China （Grant Nos. 60974078 and 10832006）.
文摘In the study of complex networks, it is commonly believed that the eigenratio λ2/λN of the Laplacian matrix of a network represents the network synchronizability, especially for symmetric networks. This paper gives two counterexamples to show that this is not true for the case where the network has a disconnected synchronized region. Consequently, a simple answer is presented to the question of when the eigenratio λ2/λN does represent the network synchronizability.
文摘Anorectal melanoma is a very rare tumor with poor prognosis. Rectal bleeding is the most frequent symptom and surgical treatment ranges from local excision to radical abdominoperineal resection. We report a case of a 75-years-old male patient who presented with a history of recurrent rectal bleeding, and whose histopathological diagnosis was melanoma. Macroscopically, we found two distinct tumors in anorectal region, 0.5 cm and 1.5 cm from dentate line. The first one was pedunculated, on a thin stalk, measuring 1 cm in greatest diameter, and the second one was sessile and nodular measuring up to 2.8 cm in largest diameter. Microscopic examination and immunohistochemical analysis of both tumors confirmed the diagnosis of melanoma. This case represents multiple synchronous primary melanoma of the anorectal region, with a possibility that one of the lesions is primary melanoma and the second one is a satellite lesion.
基金National Natural Science Foundation of China (40474023).
文摘The primary results have been obtained by the analyses on the deviation of macroscopic epicenters from relevant microscopic epicenters determined rapidly after the 139 earthquake events occunrred during 1989-2004. Further study has proved the normal distributions exist in both the east and west parts of Chinese mainland partitioned along meridian 105°E. The empirical two-dimensional normal distribution functions for the deviations are presented in the paper. The results are of significance in reducing uncertainty of losses assessment immediately after a destroyed earthquake.
文摘针对弱连接条件下锁相环同步电压源变流器WG-VSC(weak grid connected voltage source converter)系统的暂态同步稳定问题,首先建立了适用于分析WG-VSC系统在严重电网故障期间的锁相环同步暂态稳定问题的等效转子摇摆方程模型。然后利用改进的等面积定则I-EAC(improved equal area criterion)揭示了弱连接条件下VSC并网系统在严重电网故障下的暂态同步失稳机理;在此基础上,给出了系统在严重电网故障等大扰动下的保证系统暂态稳定的注入电流暂态稳定域的解析边界,为故障期间注入电流策略的制定提供了理论依据。最后,在PSCAD/EMTDC搭建了WG-VSC系统的详细开关模型,仿真结果验证了等效转子摇摆方程模型以及注入电流稳定域的有效性。
