Optical phase transfer via fiber optics is the most effective method for optical frequency standard comparison on the scale below thousands of kilometers.However,the monotonic phase discrimination range of conventiona...Optical phase transfer via fiber optics is the most effective method for optical frequency standard comparison on the scale below thousands of kilometers.However,the monotonic phase discrimination range of conventional optical phase-locked loops is limited,and link delays restrict the control bandwidth,which makes it a challenge to achieve a continuously reliable optical link.This paper presents an event-timing-based phase detection method that overcomes the monotonic phase discrimination range limitation of conventional phase-locked loops through dual-edge timestamp recording,achieving an optical phase measurement resolution on the order of 10 attoseconds.With such a technique,we established a 7-segment-cascaded optical link over 1402km of commercial fiber while sharing dense wavelength division multiplexing(DWDM)channels with live telecom traffic.The system maintained continuous operation for 11.7 days without phase cycle slips despite encountering 15 km aerial fiber noise up to 21000 rad^(2)·Hz^(−1)·km^(−1)at 1 Hz.Relative instabilities of the link are 3.7×10^(−15)at 1 s and 3.9×10^(−20)at 100000 s.展开更多
Intelligent assembly of large-scale,complex structures using an intelligent manufacturing platform represents the future development direction for industrial manufacturing.During large-scale structural assembly proces...Intelligent assembly of large-scale,complex structures using an intelligent manufacturing platform represents the future development direction for industrial manufacturing.During large-scale structural assembly processes,several bottleneck problems occur in the existing auxiliary assembly technology.First,the traditional LiDARbased assembly technology is often limited by the openness of the manufacturing environment,in which there are blind spots,and continuous online assembly adjustment thus cannot be realized.Second,for assembly of large structures,a single-station LiDAR system cannot achieve complete coverage,which means that a multi-station combination method must be used to acquire the complete three-dimensional data;many more data errors are caused by the transfer between stations than by the measurement accuracy of a single station,which means that the overall system's measurement and adjustment errors are increased greatly.Third,because of the large numbers of structural components contained in a large assembly,the accumulated errors may lead to assembly interference,but the LiDAR-assisted assembly process does not have a feedback perception capability,and thus assembly component loss can easily be caused when assembly interference occurs.Therefore,this paper proposes to combine an optical fiber sensor network with digital twin technology,which will allow the test data from the assembly entity state in the real world to be applied to the"twin"model in the virtual world and thus solve the problems with test openness and data transfer.The problem of station and perception feedback is also addressed and represents the main innovation of this work.The system uses an optical fiber sensor network as a flexible sensing medium to monitor the strain field distribution within a complex area in real time,and then completes real-time parameter adjustment of the virtual assembly based on the distributed data.Complex areas include areas that are laser-unreachable,areas with complex contact surfaces,and areas with large-scale bending deformations.An assembly condition monitoring system is designed based on the optical fiber sensor network,and an assembly condition monitoring algorithm based on multiple physical quantities is proposed.The feasibility of use of the optical fiber sensor network as the real-state parameter acquisition module for the digital twin intelligent assembly system is discussed.The offset of any position in the test area is calculated using the convolutional neural network of a residual module to provide the compensation parameters required for the virtual model of the assembly structure.In the model optimization parameter module,a correction data table is obtained through iterative learning of the algorithm to realize state prediction from the test data.The experiment simulates a largescale structure assembly process,and performs virtual and real mapping for a variety of situations with different assembly errors to enable correction of the digital twin data stream for the assembly process through the optical fiber sensor network.In the plane strain field calibration experiment,the maximum error among the test values for this system is 0.032 mm,and the average error is 0.014 mm.The results show that use of visual calibration can correct the test error to within a very small range.This result is equally applicable to gradient curvature surfaces and freeform surfaces.Statistics show that the average measurement accuracy error for regular surfaces is better than 11.2%,and the average measurement accuracy error for irregular surfaces is better than 14.8%.During simulation of large-scale structure assembly experiments,the average position deviation accuracy is 0.043 mm,which is in line with the designed accuracy.展开更多
An Extrinsic Fabry-Perot Interferometric (EFPI) fiber optical sensor system is an online testing system for the gas density. The system achieves the measurement of gas density information mainly by demodulating the ca...An Extrinsic Fabry-Perot Interferometric (EFPI) fiber optical sensor system is an online testing system for the gas density. The system achieves the measurement of gas density information mainly by demodulating the cavity length of EF- PI fiber optical sensor. There are many ways to achieve the demodulation of the cavity length. For shortcomings of the big intensity demodulation error and complex structure of phase demodulation, this paper proposes that BP neural net-work is used to locate the special peak points in normalized interference spectrum and combining the advantages of the unimodal and bimodal measurement achieves the demodulation of the cavity length. Through online simulation and actual measurement, the results show that the peak positioning technology based on BP neural network can not only achieve high-precision demodulation of the cavity length, but also achieve an absolute measurement of cavity length in large dynamic range.展开更多
In order to improve the multiplexing capability of the optical sensors based on the lower interferential optic fiber sensing technology and the white light fiber-optic Mach-Zehnder interferometer,reflective ladder top...In order to improve the multiplexing capability of the optical sensors based on the lower interferential optic fiber sensing technology and the white light fiber-optic Mach-Zehnder interferometer,reflective ladder topology network ( RLT) with tailored formula was proposed. The topology network consists of 6 rungs sensing elements linked by 5 couplers. Two cases with different choices of couplers were contrasted: one is equal coupling ratio,and the other is tailored coupling ratio. Through the simulation of these two cases,the detailed multiplexing capability was analyzed,and accordingly the experiments were also carried out. The simulation results showed that,the tailored formula enhances the multiplexing capability of the structure. In the first case, the maximum number of sensors which can be multiplexed is 8,and in the other case is 12 fiber optic sensors. The experimental results have a good agreement with numerical simulation results. Thus,it is considered expedient to incorporate RLT into large-scale building,grounds,bridges,dams,tunnels,highways and perimeter security.展开更多
To investigate wavelength response of the no core fiber（NCF）interference spectrum to concentration,a three-layer back propagation（BP）neural network model was established to optimize the concentration sensing data....To investigate wavelength response of the no core fiber（NCF）interference spectrum to concentration,a three-layer back propagation（BP）neural network model was established to optimize the concentration sensing data.In this method,the measured wavelength and the corresponding concentration were trained by a BP neural network,so that the accuracy of the measurement system was optimized.The wavelength was used as the training set and got into the input layer of the three layer BP network model which is used as the input value of the network,and the corresponding actual concentration value was used as the output value of the network,and the optimal network structure was trained.This paper discovers a preferable correlation between the predicted value and the actual value,where the former is approximately equal to the latter.The correlation coefficients of the measured and predicted values for a sucrose concentration were 1.000 89 and 1.003 94;similarly,correlations of0.999 51 and 1.018 8 for a glucose concentration were observed.The results demonstrate that the BP neural network can improve the prediction accuracy of the nonlinear relationship between the interference spectral data and the concentration in NCF sensing systems.展开更多
Packet contention is a key issue in optical packet switch (OPS) networks and finds a viable solution by including optical buffering techniques incorporating fiber delay lines (FDLs) in the switch architecture. The pre...Packet contention is a key issue in optical packet switch (OPS) networks and finds a viable solution by including optical buffering techniques incorporating fiber delay lines (FDLs) in the switch architecture. The present paper proposes a novel switch architecture for packet contention resolution in synchronous OPS network employing the packet circulation in FDLs in a synchronized manner. A mathematical model for the proposed switch architecture is developed employing packet queuing control to estimate the blocking probability for the incoming traffic. The switch performance is analyzed with a suitable contention resolution al-gorithm through the computer simulation. The simulation results substantiate the proposed model for the switch architecture.展开更多
With the rise of cloud computing in recent years, a large number of streaming media has yielded an exponential growth in network traffic. With the now present 5G and future 6G, the development of the Internet of Thing...With the rise of cloud computing in recent years, a large number of streaming media has yielded an exponential growth in network traffic. With the now present 5G and future 6G, the development of the Internet of Things (IoT), social networks, video on demand, and mobile multimedia platforms, the backbone network is bound to bear more traffic. The transmission capacity of Single Core Fiber (SCFs) may be limited in the future and Spatial Division Multiplexing (SDM) leveraging multi-core fibers promises to be one of the solutions for the future. Currently, Elastic optical networks (EONs) with multi-core fibers (MCFs) are a kind of SDM-enabled EONs (SDM-EON) used to enhance the capacity of transmission. The resource assignment in MCFs, however, will be subject to Inter-Core Crosstalk (IC-XT), hence, reducing the effectiveness of transmission. This research highlights the routing, modulation level, and spectrum assignment (RMLSA) problems with anycast traffic mode in SDM-EON. A multipath routing scheme is used to reduce the blocking rate of anycast traffic in SDM-EON with the limit of inter-core crosstalk. Hence, an integer linear programming (ILP) problem is formulated and a heuristic algorithm is proposed. Two core-assignment strategies: First-Fit (FF) and Random-Fit (RF) are used and their performance is evaluated through simulations. The simulation results show that the multipath routing method is better than the single-path routing method in terms of blocking ratio and spectrum utilization ratio. Moreover, the FF is better than the RF in low traffic load in terms of blocking ratio (BR), and the opposite in high traffic load. The FF is better than the RF in terms of a spectrum utilization ratio. In an anycast protection problem, the proposed algorithm has a lower BR than previous works.展开更多
Structural health monitoring(SHM)in service has attracted increasing attention for years.Load localization on a structure is studied hereby.Two algorithms,i.e.,support vector machine(SVM)method and back propagation ne...Structural health monitoring(SHM)in service has attracted increasing attention for years.Load localization on a structure is studied hereby.Two algorithms,i.e.,support vector machine(SVM)method and back propagation neural network(BPNN)algorithm,are proposed to identify the loading positions individually.The feasibility of the suggested methods is evaluated through an experimental program on a carbon fiber reinforced plastic laminate.The experimental tests involve in application of four optical fiber-based sensors for strain measurement at discrete points.The sensors are specially designed fiber Bragg grating(FBG)in small diameter.The small-diameter FBG sensors are arrayed in 2-D on the laminate surface.The testing results indicate that the loading position could be detected by the proposed method.Using SVM method,the 2-D FBG sensors can approximate the loading location with maximum error less than 14 mm.However,the maximum localization error could be limited to about 1 mm by applying the BPNN algorithm.It is mainly because the convergence conditions(mean square error)can be set in advance,while SVM cannot.展开更多
Being directed against two kinds of noise in optical fiber sensors,a simple and effective method of automatic compensation for optical fiber sensors is presented.Not only the unstability effect of light source,but als...Being directed against two kinds of noise in optical fiber sensors,a simple and effective method of automatic compensation for optical fiber sensors is presented.Not only the unstability effect of light source,but also zero drift of photoelectronic devices,can be eliminated or enormously restrained with the aid of this method.In another way,by using single-chip microcomputer,the optical fiber sensor system fabricated is connected to a computer network to realize an automatic compensation.展开更多
提出并模拟证明了基于电光相位调制(PM)和布拉格光纤光栅(FBG)实现受抑光载波的双边带(DSBOCS,Double-Sideband with Optical Carrier Suppression)的双向Radio over Fiber(RoF)传输系统网络设计方案.激光光源置于中心站,载有信息的光...提出并模拟证明了基于电光相位调制(PM)和布拉格光纤光栅(FBG)实现受抑光载波的双边带(DSBOCS,Double-Sideband with Optical Carrier Suppression)的双向Radio over Fiber(RoF)传输系统网络设计方案.激光光源置于中心站,载有信息的光信号通过光纤到达基站后经FBG分成两路,其中一路是被接收的下行信号,另一路作为上行信号调制后返回中心站.通过FBG,其下行信号不但实现了受抑光载波的双边带———使通信带宽加倍,上行信号作为光源通过电光强度调制,有效地实现信息的上载.仿真结果表明,光源发射功率为3 dBm,无光放大,在色散系数为20 ps/(nm.km),衰减系数为0.25 dB/km的单模光纤中传输,超高频RF信号的频率可达24 GHz,系统码元传输速率可达2.5 Gbit/s、传输距离50 km以上.展开更多
提出并模拟证明了基于两个电光相位调制器实现抑光载波双边带(Radio on Fiber,RoF)双工传输系统设计方案.通过改变电光相位调制器的最大相偏量,实现了抑光载波双边带信号传输——使通信带宽加倍,而且很好地控制上下行传输信号的误码率....提出并模拟证明了基于两个电光相位调制器实现抑光载波双边带(Radio on Fiber,RoF)双工传输系统设计方案.通过改变电光相位调制器的最大相偏量,实现了抑光载波双边带信号传输——使通信带宽加倍,而且很好地控制上下行传输信号的误码率.仿真模拟结果表明,发射功率为3dBm的光信号在无放大、色散系数为20ps/(nm.km)、衰减系数为0.25dB/km的SMF-28单模光纤中传输时,其超高频RF调制信号的频率可达24GHz,数据码元传输速率可达2.5Gbit/s,传输距离40km以上.展开更多
This paper describes current situation and special requirements of local electric power communication network in China. The paper discusses the disadvantages of SDH and fiber loop carrier system applied to electric po...This paper describes current situation and special requirements of local electric power communication network in China. The paper discusses the disadvantages of SDH and fiber loop carrier system applied to electric power communication network. It presents a new Communication System-IDS-2000 integrated digital communication system. The paper introduces the characteristics and application of IDS-2000 system in the local electric power communication network.展开更多
The motivation behind this work is the need for performance analysis of Al-Gehad/Baghdad“Fiber To The Home”(FTTH) network which is one of the Iraq Telecommunication Post and Company(ITPC) FTTH projectsin2010 in Bagh...The motivation behind this work is the need for performance analysis of Al-Gehad/Baghdad“Fiber To The Home”(FTTH) network which is one of the Iraq Telecommunication Post and Company(ITPC) FTTH projectsin2010 in Baghdad City. Based on the detailed study of this project, the design, implementation, and analysis of this network has been putting under consideration through a mathematical model simulated and performance evaluated. The link utilization and number of OLT ports (PON) had been studied and evaluated as a function of cycle time. Cost optimization was done through evaluation the total cost of PON system and who it affected with the number of ONUs (i.e. splitting ratio), as well as cost ratio between EPON and GPON is evaluated. Then GPON system has been optimized to analyze and evaluate the feeder network cost, distribution network cost, and total network cost.展开更多
In this Letter, we propose two crosstalk-aware routing, core, and spectrum assignment （CA-RCSA） algorithms for spatial division multiplexing enabled elastic optical networks （SDM-EONs） with multi-core fibers. Firs...In this Letter, we propose two crosstalk-aware routing, core, and spectrum assignment （CA-RCSA） algorithms for spatial division multiplexing enabled elastic optical networks （SDM-EONs） with multi-core fibers. First, the RCSA problem is modeled, and then a metric, i.e., CA spectrum compactness （CASC）, is designed to measure the spectrum status in SDM-EONs. Based on CASC, we propose two CA-RCSA algorithms, the first-fit （FF） CASC algorithm and the random-fit （RF） CASC algorithm. Simulation results show that our proposed algorithms can achieve better performance than the baseline algorithm in terms of blocking probability and spectrum utilization, with FF-CASC providing the best performance.展开更多
The deep understanding on sand and sand dunes scale can be useful to reveal the formation mechanism of the sandstorm for early sandstorm forecast. The current sandstorm observation methods are mainly based on conventi...The deep understanding on sand and sand dunes scale can be useful to reveal the formation mechanism of the sandstorm for early sandstorm forecast. The current sandstorm observation methods are mainly based on conventional meteorological station and satellites remote sensing, which are difficult to acquire sand scale information. A wireless sensing network is implemented in the hinterland of desert, which includes ad hoc network,sensor, global positioning system(GPS) and system integration technology. The wireless network is a three-layer architecture and daisy chain topology network, which consists of control station, master robots and slave robots.Every three robots including one master robot and its two slave robots forms an ad hoc network. Master robots directly communicate with radio base station. Information will be sent to remote information center. Data sensing system including different kinds of sensors and desert robots is developed. A desert robot is designed and implemented as unmanned probing movable nodes and sensors' carrier. A new optical fiber sensor is exploited to measure vibration of sand in particular. The whole system, which is delivered to the testing field in hinterland of desert(25 km far from base station), has been proved efficient for data acquisition.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2020YFC2200103)the Shandong Provincial Natural Science Foundation(Grant Nos.ZR2022LLZ006 and ZR2022LLZ011)+1 种基金the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0300904 and 2021ZD0300903)the Key R&D Plan of Shandong Province(Grant No.2023CXPT105)。
文摘Optical phase transfer via fiber optics is the most effective method for optical frequency standard comparison on the scale below thousands of kilometers.However,the monotonic phase discrimination range of conventional optical phase-locked loops is limited,and link delays restrict the control bandwidth,which makes it a challenge to achieve a continuously reliable optical link.This paper presents an event-timing-based phase detection method that overcomes the monotonic phase discrimination range limitation of conventional phase-locked loops through dual-edge timestamp recording,achieving an optical phase measurement resolution on the order of 10 attoseconds.With such a technique,we established a 7-segment-cascaded optical link over 1402km of commercial fiber while sharing dense wavelength division multiplexing(DWDM)channels with live telecom traffic.The system maintained continuous operation for 11.7 days without phase cycle slips despite encountering 15 km aerial fiber noise up to 21000 rad^(2)·Hz^(−1)·km^(−1)at 1 Hz.Relative instabilities of the link are 3.7×10^(−15)at 1 s and 3.9×10^(−20)at 100000 s.
基金supported by the National Science Foundation of China(Theoretical Model and Experimental Research on the Novel FBG Sensing System based on the Fusion Algorithm,No.61703056)the Jilin Province Science and Technology Development Plan Project(No.20190103154JH)。
文摘Intelligent assembly of large-scale,complex structures using an intelligent manufacturing platform represents the future development direction for industrial manufacturing.During large-scale structural assembly processes,several bottleneck problems occur in the existing auxiliary assembly technology.First,the traditional LiDARbased assembly technology is often limited by the openness of the manufacturing environment,in which there are blind spots,and continuous online assembly adjustment thus cannot be realized.Second,for assembly of large structures,a single-station LiDAR system cannot achieve complete coverage,which means that a multi-station combination method must be used to acquire the complete three-dimensional data;many more data errors are caused by the transfer between stations than by the measurement accuracy of a single station,which means that the overall system's measurement and adjustment errors are increased greatly.Third,because of the large numbers of structural components contained in a large assembly,the accumulated errors may lead to assembly interference,but the LiDAR-assisted assembly process does not have a feedback perception capability,and thus assembly component loss can easily be caused when assembly interference occurs.Therefore,this paper proposes to combine an optical fiber sensor network with digital twin technology,which will allow the test data from the assembly entity state in the real world to be applied to the"twin"model in the virtual world and thus solve the problems with test openness and data transfer.The problem of station and perception feedback is also addressed and represents the main innovation of this work.The system uses an optical fiber sensor network as a flexible sensing medium to monitor the strain field distribution within a complex area in real time,and then completes real-time parameter adjustment of the virtual assembly based on the distributed data.Complex areas include areas that are laser-unreachable,areas with complex contact surfaces,and areas with large-scale bending deformations.An assembly condition monitoring system is designed based on the optical fiber sensor network,and an assembly condition monitoring algorithm based on multiple physical quantities is proposed.The feasibility of use of the optical fiber sensor network as the real-state parameter acquisition module for the digital twin intelligent assembly system is discussed.The offset of any position in the test area is calculated using the convolutional neural network of a residual module to provide the compensation parameters required for the virtual model of the assembly structure.In the model optimization parameter module,a correction data table is obtained through iterative learning of the algorithm to realize state prediction from the test data.The experiment simulates a largescale structure assembly process,and performs virtual and real mapping for a variety of situations with different assembly errors to enable correction of the digital twin data stream for the assembly process through the optical fiber sensor network.In the plane strain field calibration experiment,the maximum error among the test values for this system is 0.032 mm,and the average error is 0.014 mm.The results show that use of visual calibration can correct the test error to within a very small range.This result is equally applicable to gradient curvature surfaces and freeform surfaces.Statistics show that the average measurement accuracy error for regular surfaces is better than 11.2%,and the average measurement accuracy error for irregular surfaces is better than 14.8%.During simulation of large-scale structure assembly experiments,the average position deviation accuracy is 0.043 mm,which is in line with the designed accuracy.
文摘An Extrinsic Fabry-Perot Interferometric (EFPI) fiber optical sensor system is an online testing system for the gas density. The system achieves the measurement of gas density information mainly by demodulating the cavity length of EF- PI fiber optical sensor. There are many ways to achieve the demodulation of the cavity length. For shortcomings of the big intensity demodulation error and complex structure of phase demodulation, this paper proposes that BP neural net-work is used to locate the special peak points in normalized interference spectrum and combining the advantages of the unimodal and bimodal measurement achieves the demodulation of the cavity length. Through online simulation and actual measurement, the results show that the peak positioning technology based on BP neural network can not only achieve high-precision demodulation of the cavity length, but also achieve an absolute measurement of cavity length in large dynamic range.
基金Sponsored by the Natural Science Foundation of Heilongjiang Province (Grant No. QC2012C081)the Creative Qualified Scientists and Technicians Foundation of Harbin City (Grant No. RC2012QN001025)the National Natural Science Foundation of China (Grant No. 61107069 and 41174161)
文摘In order to improve the multiplexing capability of the optical sensors based on the lower interferential optic fiber sensing technology and the white light fiber-optic Mach-Zehnder interferometer,reflective ladder topology network ( RLT) with tailored formula was proposed. The topology network consists of 6 rungs sensing elements linked by 5 couplers. Two cases with different choices of couplers were contrasted: one is equal coupling ratio,and the other is tailored coupling ratio. Through the simulation of these two cases,the detailed multiplexing capability was analyzed,and accordingly the experiments were also carried out. The simulation results showed that,the tailored formula enhances the multiplexing capability of the structure. In the first case, the maximum number of sensors which can be multiplexed is 8,and in the other case is 12 fiber optic sensors. The experimental results have a good agreement with numerical simulation results. Thus,it is considered expedient to incorporate RLT into large-scale building,grounds,bridges,dams,tunnels,highways and perimeter security.
基金Supported by the National Natural Science Foundation of China(61307122)the University Science and Technology Innovation Team Support Project of Henan Province(13IRTTHN016)the Innovative and Training Project of Post Graduate Funding from the Henan Normal University(201310476046)
文摘To investigate wavelength response of the no core fiber（NCF）interference spectrum to concentration,a three-layer back propagation（BP）neural network model was established to optimize the concentration sensing data.In this method,the measured wavelength and the corresponding concentration were trained by a BP neural network,so that the accuracy of the measurement system was optimized.The wavelength was used as the training set and got into the input layer of the three layer BP network model which is used as the input value of the network,and the corresponding actual concentration value was used as the output value of the network,and the optimal network structure was trained.This paper discovers a preferable correlation between the predicted value and the actual value,where the former is approximately equal to the latter.The correlation coefficients of the measured and predicted values for a sucrose concentration were 1.000 89 and 1.003 94;similarly,correlations of0.999 51 and 1.018 8 for a glucose concentration were observed.The results demonstrate that the BP neural network can improve the prediction accuracy of the nonlinear relationship between the interference spectral data and the concentration in NCF sensing systems.
文摘Packet contention is a key issue in optical packet switch (OPS) networks and finds a viable solution by including optical buffering techniques incorporating fiber delay lines (FDLs) in the switch architecture. The present paper proposes a novel switch architecture for packet contention resolution in synchronous OPS network employing the packet circulation in FDLs in a synchronized manner. A mathematical model for the proposed switch architecture is developed employing packet queuing control to estimate the blocking probability for the incoming traffic. The switch performance is analyzed with a suitable contention resolution al-gorithm through the computer simulation. The simulation results substantiate the proposed model for the switch architecture.
文摘With the rise of cloud computing in recent years, a large number of streaming media has yielded an exponential growth in network traffic. With the now present 5G and future 6G, the development of the Internet of Things (IoT), social networks, video on demand, and mobile multimedia platforms, the backbone network is bound to bear more traffic. The transmission capacity of Single Core Fiber (SCFs) may be limited in the future and Spatial Division Multiplexing (SDM) leveraging multi-core fibers promises to be one of the solutions for the future. Currently, Elastic optical networks (EONs) with multi-core fibers (MCFs) are a kind of SDM-enabled EONs (SDM-EON) used to enhance the capacity of transmission. The resource assignment in MCFs, however, will be subject to Inter-Core Crosstalk (IC-XT), hence, reducing the effectiveness of transmission. This research highlights the routing, modulation level, and spectrum assignment (RMLSA) problems with anycast traffic mode in SDM-EON. A multipath routing scheme is used to reduce the blocking rate of anycast traffic in SDM-EON with the limit of inter-core crosstalk. Hence, an integer linear programming (ILP) problem is formulated and a heuristic algorithm is proposed. Two core-assignment strategies: First-Fit (FF) and Random-Fit (RF) are used and their performance is evaluated through simulations. The simulation results show that the multipath routing method is better than the single-path routing method in terms of blocking ratio and spectrum utilization ratio. Moreover, the FF is better than the RF in low traffic load in terms of blocking ratio (BR), and the opposite in high traffic load. The FF is better than the RF in terms of a spectrum utilization ratio. In an anycast protection problem, the proposed algorithm has a lower BR than previous works.
基金supported by the National Natural Science Foundation of China(Nos.11402112,51405223)
文摘Structural health monitoring(SHM)in service has attracted increasing attention for years.Load localization on a structure is studied hereby.Two algorithms,i.e.,support vector machine(SVM)method and back propagation neural network(BPNN)algorithm,are proposed to identify the loading positions individually.The feasibility of the suggested methods is evaluated through an experimental program on a carbon fiber reinforced plastic laminate.The experimental tests involve in application of four optical fiber-based sensors for strain measurement at discrete points.The sensors are specially designed fiber Bragg grating(FBG)in small diameter.The small-diameter FBG sensors are arrayed in 2-D on the laminate surface.The testing results indicate that the loading position could be detected by the proposed method.Using SVM method,the 2-D FBG sensors can approximate the loading location with maximum error less than 14 mm.However,the maximum localization error could be limited to about 1 mm by applying the BPNN algorithm.It is mainly because the convergence conditions(mean square error)can be set in advance,while SVM cannot.
文摘Being directed against two kinds of noise in optical fiber sensors,a simple and effective method of automatic compensation for optical fiber sensors is presented.Not only the unstability effect of light source,but also zero drift of photoelectronic devices,can be eliminated or enormously restrained with the aid of this method.In another way,by using single-chip microcomputer,the optical fiber sensor system fabricated is connected to a computer network to realize an automatic compensation.
文摘提出并模拟证明了基于两个电光相位调制器实现抑光载波双边带(Radio on Fiber,RoF)双工传输系统设计方案.通过改变电光相位调制器的最大相偏量,实现了抑光载波双边带信号传输——使通信带宽加倍,而且很好地控制上下行传输信号的误码率.仿真模拟结果表明,发射功率为3dBm的光信号在无放大、色散系数为20ps/(nm.km)、衰减系数为0.25dB/km的SMF-28单模光纤中传输时,其超高频RF调制信号的频率可达24GHz,数据码元传输速率可达2.5Gbit/s,传输距离40km以上.
文摘This paper describes current situation and special requirements of local electric power communication network in China. The paper discusses the disadvantages of SDH and fiber loop carrier system applied to electric power communication network. It presents a new Communication System-IDS-2000 integrated digital communication system. The paper introduces the characteristics and application of IDS-2000 system in the local electric power communication network.
文摘The motivation behind this work is the need for performance analysis of Al-Gehad/Baghdad“Fiber To The Home”(FTTH) network which is one of the Iraq Telecommunication Post and Company(ITPC) FTTH projectsin2010 in Baghdad City. Based on the detailed study of this project, the design, implementation, and analysis of this network has been putting under consideration through a mathematical model simulated and performance evaluated. The link utilization and number of OLT ports (PON) had been studied and evaluated as a function of cycle time. Cost optimization was done through evaluation the total cost of PON system and who it affected with the number of ONUs (i.e. splitting ratio), as well as cost ratio between EPON and GPON is evaluated. Then GPON system has been optimized to analyze and evaluate the feeder network cost, distribution network cost, and total network cost.
基金supported by the National Natural Science Foundation of China(Nos.61571058 and 61501049)the National 863 Project of China(No.2015AA015503)+2 种基金the State Key Laboratory of Information Photonics and Optical Communications(Nos.IPOC2014ZZ03 and IPOC2015ZT01)the Chinese Scholarship Council(CSC),BUPT Excellent Ph.D.Students Foundation(No.CX2015307)the NSF Project(No.CNS-1302645).
文摘In this Letter, we propose two crosstalk-aware routing, core, and spectrum assignment （CA-RCSA） algorithms for spatial division multiplexing enabled elastic optical networks （SDM-EONs） with multi-core fibers. First, the RCSA problem is modeled, and then a metric, i.e., CA spectrum compactness （CASC）, is designed to measure the spectrum status in SDM-EONs. Based on CASC, we propose two CA-RCSA algorithms, the first-fit （FF） CASC algorithm and the random-fit （RF） CASC algorithm. Simulation results show that our proposed algorithms can achieve better performance than the baseline algorithm in terms of blocking probability and spectrum utilization, with FF-CASC providing the best performance.
基金International S&T Cooperation Program of China(No.2011DFA11780)
文摘The deep understanding on sand and sand dunes scale can be useful to reveal the formation mechanism of the sandstorm for early sandstorm forecast. The current sandstorm observation methods are mainly based on conventional meteorological station and satellites remote sensing, which are difficult to acquire sand scale information. A wireless sensing network is implemented in the hinterland of desert, which includes ad hoc network,sensor, global positioning system(GPS) and system integration technology. The wireless network is a three-layer architecture and daisy chain topology network, which consists of control station, master robots and slave robots.Every three robots including one master robot and its two slave robots forms an ad hoc network. Master robots directly communicate with radio base station. Information will be sent to remote information center. Data sensing system including different kinds of sensors and desert robots is developed. A desert robot is designed and implemented as unmanned probing movable nodes and sensors' carrier. A new optical fiber sensor is exploited to measure vibration of sand in particular. The whole system, which is delivered to the testing field in hinterland of desert(25 km far from base station), has been proved efficient for data acquisition.
