短波分集通信网采用多个频率保障用户通信,以提高接收可靠性。当前,其采用“先到先得、用后释放”的方式为用户通信提供频率保障。在多用户并发接入时,存在频率资源消耗过大和频率资源浪费问题。本文提出对短波分集通信网频率资源进行规...短波分集通信网采用多个频率保障用户通信,以提高接收可靠性。当前,其采用“先到先得、用后释放”的方式为用户通信提供频率保障。在多用户并发接入时,存在频率资源消耗过大和频率资源浪费问题。本文提出对短波分集通信网频率资源进行规划,以满足给定用户需求情况下使用最少频率为优化目标进行建模,并利用遗传算法对模型进行求解。仿真结果表明,采用遗传算法对用户进行频率规划比“先到先得、用后释放”的方式具有更高的频率利用效率,证明了短波分集网服务大量用户时采用频率规划的必要性。HF diversity communication network adopts multiple frequencies to support user communication, in order to improve the reliability of receiving. At present, it adopts the method of “first come, first served, release after use” to provide a frequency guarantee for user communication. When multiple users access concurrently, there are problems of excessive consumption and the waste of frequency resources. In this paper, we propose the frequency resource planning of HF diversity communication network and model the optimization goal using the least frequency to meet the given user’s needs, and a genetic algorithm is used to solve the model. The simulation results show genetic algorithm has higher frequency utilization efficiency than the “first come, first served, release after use” method, which proves the necessity of frequency planning when the HF diversity network serves a large number of users.展开更多
The major constraint on the performance of orthogonal frequency division multiplexing （OFDM） based underwater acoustic （UWA） communication is to keep subcarriers orthogonal. In this paper, Doppler estimation and t...The major constraint on the performance of orthogonal frequency division multiplexing （OFDM） based underwater acoustic （UWA） communication is to keep subcarriers orthogonal. In this paper, Doppler estimation and the respective compensation technique along with various diversity techniques were deliberated for OFDM-based systems best suited for underwater wireless information exchange. In practice, for mobile communication, adjustment and tuning of transducers in order to get spatial diversity is extremely difficult. Considering the relatively low coherence bandwidth in UWA, the frequency diversity design with the Doppler compensation function was elaborated here. The outfield experiments of mobile underwater acoustic communication （UWAC） based on OFDM were carried out with 0.17 bit/（s-Hz） spectral efficiency. The validity and the dependability of the scheme were also analyzed.展开更多
The user signal quality as well as the performance of transmission link experiences severe loss due to wireless channel fading and propagation loss in high-speed railway scenario.To improve the quality at the receivin...The user signal quality as well as the performance of transmission link experiences severe loss due to wireless channel fading and propagation loss in high-speed railway scenario.To improve the quality at the receiving end,spatial diversity was realized by means of cooperative communication technology based on the uncorrelated characteristics of the channels.The model of mobile communication system in high-speed railway was set up,and a cooperative scheme based on statistics was proposed.Mathematical analysis and simulation results show that the quality of the received signal and the performance of the transmission link are significantly improved using cooperative communication technology compared to that in non-cooperative communication mode.展开更多
A novel distributed numerical control (DNC) integrated system based on plug-in software technology is proposed. It connects new or old numerical control (NC) machine tools which have inhomogeneous numerical control sy...A novel distributed numerical control (DNC) integrated system based on plug-in software technology is proposed. It connects new or old numerical control (NC) machine tools which have inhomogeneous numerical control systems with CAD/CAM system by CANbus network. A DNC computer is able to control 15 sets of NC machine tools reliably at the same time. The novel DNC system increases the efficiency of machine tools and improve the production management level by realizing non-paper production, agile manufacturing, networked manufacturing and so on in the near future. Key technologies to construct the novel DNC integrated system include the integration of inhomogeneous numerical control systems, NC program restart, and algorithm for communication competition. Such system has demonstrated successful applications in some corporations that have acquired good economic benefits and social effects.展开更多
The disequilibrium of the optical power among different channels is analyzed for the dense wavelength division multiplexing optical communication systems. And the new technologies and devices for optical amplifying, f...The disequilibrium of the optical power among different channels is analyzed for the dense wavelength division multiplexing optical communication systems. And the new technologies and devices for optical amplifying, filtering, adding /dropping,etc,have been reviewed, which can be used to equalize dynamically the optical power in optical networks.展开更多
Multiwavelength chirped fiber Bragg grating (MCFBG) is a more valuable approach to chromatic dispersion compensation. And adjusting the structure of FBG will optimize the performance of dispersion compensator in 8...Multiwavelength chirped fiber Bragg grating (MCFBG) is a more valuable approach to chromatic dispersion compensation. And adjusting the structure of FBG will optimize the performance of dispersion compensator in 8×10 Gb/s DWDM network, which is proved by simulating calculation.展开更多
A multi-Cyclic Redundancy Check (CRC) selective Hybrid Automatic-Repeat-reQuest (HARQ) scheme for improving the throughput efficiency of Multiple Input Multiple Output (MIMO) systems is proposed in this paper. Accordi...A multi-Cyclic Redundancy Check (CRC) selective Hybrid Automatic-Repeat-reQuest (HARQ) scheme for improving the throughput efficiency of Multiple Input Multiple Output (MIMO) systems is proposed in this paper. According to different feedback information from the receiver, the proposed HARQ scheme employs two strategies, referred to as retransmission frame selection and space diversity. These two strategies decrease the successive frame errors upon retransmission. Theoretic analysis and computer simulation results show that this HARQ scheme achieves higher throughput than the existing HARQ schemes even in poor conditions of low Signal-to-Noise Ratio (SNR).展开更多
CDW （construction and demolition wastes） present a high amount of aggregate chips covered with mortar. This results in high absorption of water with a direct impact in particle breakage or disaggregation. It is supp...CDW （construction and demolition wastes） present a high amount of aggregate chips covered with mortar. This results in high absorption of water with a direct impact in particle breakage or disaggregation. It is supposed that intra particle suction plays an important role in this phenomenon. However, WRCs （water retention curves） of CDW are not well understood. In this work, the WRCs of dynamically compacted specimens of aggregates recycled from the demolition of the National Stadium in Brasilia are studied. The objective of this study is to obtain WRCs of the recycled materials by using the pressure plate and filter paper methods. The breaking effect during compaction is quantified from the grain size distribution curves. The particle breakage during compaction increases when the energy is augmented. The results from the WRCs were incorporated into a pore size capillary model to predict pore size distribution.展开更多
Based on the electromagnetic field theory, the optical signal transmission characteristics in input/output waveguides, slab waveguides and arrayed waveguides of the arrayed waveguide grating (AWG) multi/demultiplexer ...Based on the electromagnetic field theory, the optical signal transmission characteristics in input/output waveguides, slab waveguides and arrayed waveguides of the arrayed waveguide grating (AWG) multi/demultiplexer are analyzed. The relationship between the physical parameters such as geometry sizes and relative refractive index in AWG multi/demultiplexer and the optical signal transmission characteristics are discussed. This theoretical study can be used for optimizing the design and improving the performance of the AWG multi/demultiplexer.展开更多
This study explores the use of augmented reality smart glasses(ARSGs) by physicians and their adoption of these products in the Turkish medical industry.Google Glass was used as a demonstrative example for the introdu...This study explores the use of augmented reality smart glasses(ARSGs) by physicians and their adoption of these products in the Turkish medical industry.Google Glass was used as a demonstrative example for the introduction of ARSGs. We proposed an exploratory model based on the technology acceptance model by Davis. Exogenous factors in the model were defined by performing semi-structured in-depth interviews, along with the use of an expert panel in addition to the technology adoption literature. The framework was tested by means of a field study, data was collected via an Internet survey, and path analysis was used. The results indicate that there were a number of factors to be considered in order to understand ARSG adoption by physicians.Usefulness was influenced by ease of use, compatibility,ease of reminding, and speech recognition, while ease of use was affected by ease of learning, ease of medical education, external influence, and privacy. Privacy was the only negative factor that reduced the perceived ease of use,and was found to indirectly create a negative attitude.Compatibility emerged as the most significant external factor for usefulness. Developers of ARSGs should pay attention to healthcare-specific requirements for improved utilization and more extensive adoption of ARSGs in healthcare settings. In particular, they should focus on how to increase the compatibility of ARSGs. Further research needs to be conducted to explain the adoption intention of physicians.展开更多
The rectangular optical filter is one of the most important optical switching components in the dense wavelength divi- sion multiplexing （DWDM） fiber-optic communication system and the intelligent optical network. T...The rectangular optical filter is one of the most important optical switching components in the dense wavelength divi- sion multiplexing （DWDM） fiber-optic communication system and the intelligent optical network. The integrated high- order silicon microring resonator （MRR） is one of the best candidates to achieve rectangular filtering spectrum re- sponse. In general, the spectrum response rectangular degree of the single MRR is very low, so it cannot be used in the DWDM system. Using the high-order MRRs, the bandwidth of flat-top pass band, the out-of-band rejection degree and the roll-off coefficient of the edge will be improved obviously. In this paper, a rectangular optical filter based on high- order MRRs with uniform couplers is presented and demonstrated. Using 15 coupled race-track MRRs with 10 pm in radius, the 3 dB flat-top pass band of 2 nm, the out-of-band rejection ratio of 30 dB and the rising and falling edges of 48 dB/nm can be realized successfully.展开更多
文摘短波分集通信网采用多个频率保障用户通信,以提高接收可靠性。当前,其采用“先到先得、用后释放”的方式为用户通信提供频率保障。在多用户并发接入时,存在频率资源消耗过大和频率资源浪费问题。本文提出对短波分集通信网频率资源进行规划,以满足给定用户需求情况下使用最少频率为优化目标进行建模,并利用遗传算法对模型进行求解。仿真结果表明,采用遗传算法对用户进行频率规划比“先到先得、用后释放”的方式具有更高的频率利用效率,证明了短波分集网服务大量用户时采用频率规划的必要性。HF diversity communication network adopts multiple frequencies to support user communication, in order to improve the reliability of receiving. At present, it adopts the method of “first come, first served, release after use” to provide a frequency guarantee for user communication. When multiple users access concurrently, there are problems of excessive consumption and the waste of frequency resources. In this paper, we propose the frequency resource planning of HF diversity communication network and model the optimization goal using the least frequency to meet the given user’s needs, and a genetic algorithm is used to solve the model. The simulation results show genetic algorithm has higher frequency utilization efficiency than the “first come, first served, release after use” method, which proves the necessity of frequency planning when the HF diversity network serves a large number of users.
基金Supported by the National High Technology Research and Development Program of China (2009AA093601-2)the National Defense Foundation Research (B2420110007)
文摘The major constraint on the performance of orthogonal frequency division multiplexing （OFDM） based underwater acoustic （UWA） communication is to keep subcarriers orthogonal. In this paper, Doppler estimation and the respective compensation technique along with various diversity techniques were deliberated for OFDM-based systems best suited for underwater wireless information exchange. In practice, for mobile communication, adjustment and tuning of transducers in order to get spatial diversity is extremely difficult. Considering the relatively low coherence bandwidth in UWA, the frequency diversity design with the Doppler compensation function was elaborated here. The outfield experiments of mobile underwater acoustic communication （UWAC） based on OFDM were carried out with 0.17 bit/（s-Hz） spectral efficiency. The validity and the dependability of the scheme were also analyzed.
基金Project of Science and Technology Research and Development Plan of China Railway Corporation(No.2013G010-D)Foundation of a Hundred Youth Talent Training Program of Lanzhou Jiaotong University
文摘The user signal quality as well as the performance of transmission link experiences severe loss due to wireless channel fading and propagation loss in high-speed railway scenario.To improve the quality at the receiving end,spatial diversity was realized by means of cooperative communication technology based on the uncorrelated characteristics of the channels.The model of mobile communication system in high-speed railway was set up,and a cooperative scheme based on statistics was proposed.Mathematical analysis and simulation results show that the quality of the received signal and the performance of the transmission link are significantly improved using cooperative communication technology compared to that in non-cooperative communication mode.
文摘A novel distributed numerical control (DNC) integrated system based on plug-in software technology is proposed. It connects new or old numerical control (NC) machine tools which have inhomogeneous numerical control systems with CAD/CAM system by CANbus network. A DNC computer is able to control 15 sets of NC machine tools reliably at the same time. The novel DNC system increases the efficiency of machine tools and improve the production management level by realizing non-paper production, agile manufacturing, networked manufacturing and so on in the near future. Key technologies to construct the novel DNC integrated system include the integration of inhomogeneous numerical control systems, NC program restart, and algorithm for communication competition. Such system has demonstrated successful applications in some corporations that have acquired good economic benefits and social effects.
文摘The disequilibrium of the optical power among different channels is analyzed for the dense wavelength division multiplexing optical communication systems. And the new technologies and devices for optical amplifying, filtering, adding /dropping,etc,have been reviewed, which can be used to equalize dynamically the optical power in optical networks.
文摘Multiwavelength chirped fiber Bragg grating (MCFBG) is a more valuable approach to chromatic dispersion compensation. And adjusting the structure of FBG will optimize the performance of dispersion compensator in 8×10 Gb/s DWDM network, which is proved by simulating calculation.
文摘A multi-Cyclic Redundancy Check (CRC) selective Hybrid Automatic-Repeat-reQuest (HARQ) scheme for improving the throughput efficiency of Multiple Input Multiple Output (MIMO) systems is proposed in this paper. According to different feedback information from the receiver, the proposed HARQ scheme employs two strategies, referred to as retransmission frame selection and space diversity. These two strategies decrease the successive frame errors upon retransmission. Theoretic analysis and computer simulation results show that this HARQ scheme achieves higher throughput than the existing HARQ schemes even in poor conditions of low Signal-to-Noise Ratio (SNR).
文摘CDW （construction and demolition wastes） present a high amount of aggregate chips covered with mortar. This results in high absorption of water with a direct impact in particle breakage or disaggregation. It is supposed that intra particle suction plays an important role in this phenomenon. However, WRCs （water retention curves） of CDW are not well understood. In this work, the WRCs of dynamically compacted specimens of aggregates recycled from the demolition of the National Stadium in Brasilia are studied. The objective of this study is to obtain WRCs of the recycled materials by using the pressure plate and filter paper methods. The breaking effect during compaction is quantified from the grain size distribution curves. The particle breakage during compaction increases when the energy is augmented. The results from the WRCs were incorporated into a pore size capillary model to predict pore size distribution.
文摘Based on the electromagnetic field theory, the optical signal transmission characteristics in input/output waveguides, slab waveguides and arrayed waveguides of the arrayed waveguide grating (AWG) multi/demultiplexer are analyzed. The relationship between the physical parameters such as geometry sizes and relative refractive index in AWG multi/demultiplexer and the optical signal transmission characteristics are discussed. This theoretical study can be used for optimizing the design and improving the performance of the AWG multi/demultiplexer.
文摘This study explores the use of augmented reality smart glasses(ARSGs) by physicians and their adoption of these products in the Turkish medical industry.Google Glass was used as a demonstrative example for the introduction of ARSGs. We proposed an exploratory model based on the technology acceptance model by Davis. Exogenous factors in the model were defined by performing semi-structured in-depth interviews, along with the use of an expert panel in addition to the technology adoption literature. The framework was tested by means of a field study, data was collected via an Internet survey, and path analysis was used. The results indicate that there were a number of factors to be considered in order to understand ARSG adoption by physicians.Usefulness was influenced by ease of use, compatibility,ease of reminding, and speech recognition, while ease of use was affected by ease of learning, ease of medical education, external influence, and privacy. Privacy was the only negative factor that reduced the perceived ease of use,and was found to indirectly create a negative attitude.Compatibility emerged as the most significant external factor for usefulness. Developers of ARSGs should pay attention to healthcare-specific requirements for improved utilization and more extensive adoption of ARSGs in healthcare settings. In particular, they should focus on how to increase the compatibility of ARSGs. Further research needs to be conducted to explain the adoption intention of physicians.
基金supported by the National Natural Science Foundation of China(No.61205062)the Scientific Research Project of Hubei Education Department(No.B2015191)the Project of Hubei Province Universities Outstanding Youth Scientific Innovation Team(Nos.T201431 and T201633)
文摘The rectangular optical filter is one of the most important optical switching components in the dense wavelength divi- sion multiplexing （DWDM） fiber-optic communication system and the intelligent optical network. The integrated high- order silicon microring resonator （MRR） is one of the best candidates to achieve rectangular filtering spectrum re- sponse. In general, the spectrum response rectangular degree of the single MRR is very low, so it cannot be used in the DWDM system. Using the high-order MRRs, the bandwidth of flat-top pass band, the out-of-band rejection degree and the roll-off coefficient of the edge will be improved obviously. In this paper, a rectangular optical filter based on high- order MRRs with uniform couplers is presented and demonstrated. Using 15 coupled race-track MRRs with 10 pm in radius, the 3 dB flat-top pass band of 2 nm, the out-of-band rejection ratio of 30 dB and the rising and falling edges of 48 dB/nm can be realized successfully.
