In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8...In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8/QPSK-OFDM signal for uplink transmission is successfully proposed and experimentally presented in a full-duplex PON based on OFDM system. Here, for the uplink, in order to unit management of the optical line terminal (OLT) and reduce cost, the optical source functioned as the optical subcarrier at optical network units (ONUs) is from OLT in the central station. Moreover, there is an external cavity laser (ECL) with center frequency of 193.2 THz not only employed as optical modulated signal but also acted as LO signal. Our simulation results show that bit error ratio (BER) under hardware detection forward error correction has been successfully gained after 20 km of SSMF transmission. It is observed that the receiver sensitivity of multilevel PSK (M-PSK) is obviously larger than that of the M-QAM in this measurement scheme.展开更多
In this letter, we present the generation, the balanced detection, and the transmission performance evaluation of dual polarization differential quadrature phase shift keying (DP-DQPSK) signals in optical access syste...In this letter, we present the generation, the balanced detection, and the transmission performance evaluation of dual polarization differential quadrature phase shift keying (DP-DQPSK) signals in optical access system integrated with fiber and free-space downlink. Polarization-multip- lexed (POLMUX) technique is introduced in the system for high spectral efficiency access utilization. 10 Gb/s DP-DQPSK downlink signals are successfully transmitted over 50 km SMF-28 and a 800 m wireless optical channel under the bad weather condition, such as fog and haze. The results show that the potentiality of DP-DQPSK optical access system is integrated with fiber and free- space downlink for providing flexible user access with high bandwidth efficiency.展开更多
Excessive temperature rise during the operation of the generator system can affect the safety and life cycle of the machine.Therefore,in order to accurately obtain the internal temperature of the switched reluctance g...Excessive temperature rise during the operation of the generator system can affect the safety and life cycle of the machine.Therefore,in order to accurately obtain the internal temperature of the switched reluctance generator(SRG),an internal temperature estimation model based on electric heating is established in this paper.First,an im-proved variable coefficient Bertotti loss separation calcula-tion formula is adopted to solve the iron loss of the genera-tor under various operating conditions.Subsequently,the accurate heat source parameters in the temperature model can be obtained,and the corresponding heat source data can be calculated.Then,based on the obtained heat source data,an equivalent thermal circuit model is established for SRG.Meanwhile,in order to effectively reduce the internal temperature during SRG operation,a new water-cooled structure for direct cooling of SRG stator windings is pro-posed in this paper,which can effectively reduce the tem-perature rise during operation,thus improving the reliabil-ity of the generator.Finally,by comparing the equivalent thermal circuit model,finite element thermal model,and experimental temperature measurements of SRG,it is found that results from the equivalent thermal circuit model of the SRG are closer to the measured temperatures,while the effectiveness of the water-cooled structure is verified.展开更多
Mountain cities are complex asymmetric dynamic network architectures,and the flight of UAVs in this environment is subject to various constraints,while efficiency is a crucial factor in the trajectory planning of poli...Mountain cities are complex asymmetric dynamic network architectures,and the flight of UAVs in this environment is subject to various constraints,while efficiency is a crucial factor in the trajectory planning of police UAVs,which need to maintain high efficiency and safe flight paths between their starting and ending points,but the traditional trajectory planning method cannot meet the requirements of rapid maneuvering of police UAVs.To achieve this,a 3D terrain map is built,an objective function is established for the flight cost in the UAV trajectory planning process,and a planning algorithm called particle swarm optimization bat algorithm(PSOBA)is proposed.PSOBA combines the characteristics of the bat algorithm(BA)and the particle swarm optimization algorithm(PSO)to improve population diversity and resolve the delayed convergence issue in the last phases of BA.Simulation results show that PSOBA is more effective than BA,with a search time for the best solution that is approximately 20.43%shorter and a convergence value of the objective function that is approximately 38%smaller.PSOBA is also able to plan a quicker,shorter,and safer flight path compared to other trail planning algorithms that enhance the bat algorithm.These findings suggest that PSOBA is a powerful algorithm with potential application value in UAV trajectory planning control in the mobile intelligence era.Contribute to the service of public social security.展开更多
文摘In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8/QPSK-OFDM signal for uplink transmission is successfully proposed and experimentally presented in a full-duplex PON based on OFDM system. Here, for the uplink, in order to unit management of the optical line terminal (OLT) and reduce cost, the optical source functioned as the optical subcarrier at optical network units (ONUs) is from OLT in the central station. Moreover, there is an external cavity laser (ECL) with center frequency of 193.2 THz not only employed as optical modulated signal but also acted as LO signal. Our simulation results show that bit error ratio (BER) under hardware detection forward error correction has been successfully gained after 20 km of SSMF transmission. It is observed that the receiver sensitivity of multilevel PSK (M-PSK) is obviously larger than that of the M-QAM in this measurement scheme.
文摘In this letter, we present the generation, the balanced detection, and the transmission performance evaluation of dual polarization differential quadrature phase shift keying (DP-DQPSK) signals in optical access system integrated with fiber and free-space downlink. Polarization-multip- lexed (POLMUX) technique is introduced in the system for high spectral efficiency access utilization. 10 Gb/s DP-DQPSK downlink signals are successfully transmitted over 50 km SMF-28 and a 800 m wireless optical channel under the bad weather condition, such as fog and haze. The results show that the potentiality of DP-DQPSK optical access system is integrated with fiber and free- space downlink for providing flexible user access with high bandwidth efficiency.
基金supported in part by the Shenzhen Col-laborative Innovation Special Plan International Coopera-tion Research Project(No.GJHZ20220913144400001)the General Research Project of Shenzhen Science and Technology Plan(No.JCYJ20220818100000001).
文摘Excessive temperature rise during the operation of the generator system can affect the safety and life cycle of the machine.Therefore,in order to accurately obtain the internal temperature of the switched reluctance generator(SRG),an internal temperature estimation model based on electric heating is established in this paper.First,an im-proved variable coefficient Bertotti loss separation calcula-tion formula is adopted to solve the iron loss of the genera-tor under various operating conditions.Subsequently,the accurate heat source parameters in the temperature model can be obtained,and the corresponding heat source data can be calculated.Then,based on the obtained heat source data,an equivalent thermal circuit model is established for SRG.Meanwhile,in order to effectively reduce the internal temperature during SRG operation,a new water-cooled structure for direct cooling of SRG stator windings is pro-posed in this paper,which can effectively reduce the tem-perature rise during operation,thus improving the reliabil-ity of the generator.Finally,by comparing the equivalent thermal circuit model,finite element thermal model,and experimental temperature measurements of SRG,it is found that results from the equivalent thermal circuit model of the SRG are closer to the measured temperatures,while the effectiveness of the water-cooled structure is verified.
基金Supported by the Science and Technology Research Program of Chongqing Municipal Education Commission(KJZD-K202201203)Chongqing Three Gorges University and the Public Security Bureau of Wanzhou District,Chongqing(wzstc20210302,wzstc20220310)。
文摘Mountain cities are complex asymmetric dynamic network architectures,and the flight of UAVs in this environment is subject to various constraints,while efficiency is a crucial factor in the trajectory planning of police UAVs,which need to maintain high efficiency and safe flight paths between their starting and ending points,but the traditional trajectory planning method cannot meet the requirements of rapid maneuvering of police UAVs.To achieve this,a 3D terrain map is built,an objective function is established for the flight cost in the UAV trajectory planning process,and a planning algorithm called particle swarm optimization bat algorithm(PSOBA)is proposed.PSOBA combines the characteristics of the bat algorithm(BA)and the particle swarm optimization algorithm(PSO)to improve population diversity and resolve the delayed convergence issue in the last phases of BA.Simulation results show that PSOBA is more effective than BA,with a search time for the best solution that is approximately 20.43%shorter and a convergence value of the objective function that is approximately 38%smaller.PSOBA is also able to plan a quicker,shorter,and safer flight path compared to other trail planning algorithms that enhance the bat algorithm.These findings suggest that PSOBA is a powerful algorithm with potential application value in UAV trajectory planning control in the mobile intelligence era.Contribute to the service of public social security.
