Fire rescue challenges and solutions have evolved from straightfor-ward plane rescue to encompass 3D space due to the rise of high-rise city buildings.Hence,this study facilitates a system with quick and simplified on...Fire rescue challenges and solutions have evolved from straightfor-ward plane rescue to encompass 3D space due to the rise of high-rise city buildings.Hence,this study facilitates a system with quick and simplified on-site launching and generates real-time location data,enabling fire rescuers to arrive at the intended spot faster and correctly for effective and precise rescue.Auto-positioning with step-by-step instructions is proposed when launching the locating system,while no extra measuring instrument like Total Station(TS)is needed.Real-time location tracking is provided via a 3D space real-time locating system(RTLS)constructed using Ultra-wide Bandwidth technology(UWB),which requires electromagnetic waves to pass through concrete walls.A hybrid weighted least squares with a time difference of arrival(WLS/TDOA)positioning method is proposed to address real path-tracking issues in 3D space and to meet RTLS requirements for quick computing in real-world applications.The 3D WLS/TDOA algorithm is theoretically constructed with the Cramer-Rao lower bound(CRLB).The computing complexity is reduced to the lower bound for embedded hardware to directly compute the time differential of the arriving signals using the time-to-digital converter(TDC).The results of the experiments show that the errors are controlled when the positioning algorithm is applied in various complicated situations to fulfill the requirements of engineering applications.The statistical analysis of the data reveals that the proposed UWB RTLS auto-positioning system can track target tags with an accuracy of 0.20 m.展开更多
A novel approach for improving antenna bandwidth is described using a 6-element Yagi-Uda array as an example. The new approach applies Central Force Optimization, a deterministic metaheuristic, and Variable Z0 technol...A novel approach for improving antenna bandwidth is described using a 6-element Yagi-Uda array as an example. The new approach applies Central Force Optimization, a deterministic metaheuristic, and Variable Z0 technology, a novel, proprietary design and optimization methodology, to produce an array with 33.09% fractional impedance bandwidth. This array’s performance is compared to its CFO-optimized Fixed Z0counterpart, and to the performance of a 6-ele- ment Dominating Cone Line Search-optimized array. Both CFO-optimized antennas exhibit better performance than the DCLS array, especially with respect to impedance bandwidth. Although the Yagi-Uda antenna was chosen to illustrate this new approach to antenna design and optimization, the methodology is entirely general and can be applied to any antenna against any set of performance objectives.展开更多
Due to its large bandwidth and the complexity of indoor environment, the ultra-wideband （UWB） channel is frequency selective, which affects the data rate and reliability of UWB communication. This paper investigates...Due to its large bandwidth and the complexity of indoor environment, the ultra-wideband （UWB） channel is frequency selective, which affects the data rate and reliability of UWB communication. This paper investigates amplify-and-forward （AF） relay scheme to mitigate this reliability problem for orthogonal frequency division multiplexing （OFDM）-UWB communication. The relay can be used to acquire capacity gain and diversity gain just like multiple-input and multiple-output （MIMO） system. The first investigation focuses on the relay-node selection criterion and combination ratio for capacity gain. Capacity gain depends on the correlation of frequency responses between direct link and relay link in addition to signal-to-noise ratio （SNR） of relay link. Increased similarity of the two frequency responses increases capacity gain. Capacity gain＇s best relay and combination ratio are found by taking the derivative of the capacity equation. Solution of the quadratic derivative equation of ratio finds the optimal ratios for every potential relay node. The second investigation focuses on relay-node selection criterion and combination ratio for diversity gain. Higher diversity gain corresponds to less deep-faded sub-channels of combined signal. Reduced computation divides the problem into two steps： the first step selects the relay node according to the criterion that is dependent on the expectation value and variance of S（f）--the function of SNR of Jq the second step solves the optimization problem for optimal combination ratio. Numerical simulation shows that our scheme is effective in pursuit of capacity gain and of diversity gain.展开更多
The microwave photonic technology-based Ultra-Wideband (UWB) Radio over Fiber (RoF) system is an important solution to the future low-cost and high-performance ultra-wideband wireless access network.Much research work...The microwave photonic technology-based Ultra-Wideband (UWB) Radio over Fiber (RoF) system is an important solution to the future low-cost and high-performance ultra-wideband wireless access network.Much research work has been done in this field with abundant results.This article introduces the RoF system that is based on the all-optical vector modulation technology to further enhance signal’s spectrum efficiency;the full-duplex RoF system that is based on the millimeter wave Phase-Shift Keying (PSK) modulation to greatly simplify base station structure and fiber layout;and the RoF system that is based on multi-service mixed transmission to carry the service with both wired signal and several wireless signals.The article also presents an RoF-based high-definition video transmission platform.展开更多
With the rapid development of science and technology,the emergence of new application scenarios,such as robots,driverless vehicles and smart city,puts forward high requirements for artificial visual systems.Optoelectr...With the rapid development of science and technology,the emergence of new application scenarios,such as robots,driverless vehicles and smart city,puts forward high requirements for artificial visual systems.Optoelectronic synaptic devices have attracted much attention due to their advantages in sensing,memory and computing integration.In this work,via band structure engineering and heterostructure designing,a heterojunction optoelectronic synaptic device based on Cu doped with n-type SrTiO_(3)(Cu:STO)film combined with p-type CuAlO_(2)(CAO)thin film was fabricated.It is found surprisingly that the optoelectronic device based on Cu:STO/CAO p-n heterojunction exhibits a rapid response of 2 ms,and that it has a wideband response from visible to near-infrared(NIR)region.Additionally,a series of important synaptic functions,including excitatory postsynaptic current(EPSC),paired-pulse facilitation(PPF),shortterm potentiation(STP)to long-term potentiation(LTP)transition,learning experience behavior and image sharpening,have been successfully simulated on the device.More importantly,the performance of the device remains still stable and reliable after several months which were stored at room temperature and atmospheric pressure.Based on these advantages,the optoelectronic synaptic devices demonstrated here provide great potential in the new generation of artificial visual systems.展开更多
文摘Fire rescue challenges and solutions have evolved from straightfor-ward plane rescue to encompass 3D space due to the rise of high-rise city buildings.Hence,this study facilitates a system with quick and simplified on-site launching and generates real-time location data,enabling fire rescuers to arrive at the intended spot faster and correctly for effective and precise rescue.Auto-positioning with step-by-step instructions is proposed when launching the locating system,while no extra measuring instrument like Total Station(TS)is needed.Real-time location tracking is provided via a 3D space real-time locating system(RTLS)constructed using Ultra-wide Bandwidth technology(UWB),which requires electromagnetic waves to pass through concrete walls.A hybrid weighted least squares with a time difference of arrival(WLS/TDOA)positioning method is proposed to address real path-tracking issues in 3D space and to meet RTLS requirements for quick computing in real-world applications.The 3D WLS/TDOA algorithm is theoretically constructed with the Cramer-Rao lower bound(CRLB).The computing complexity is reduced to the lower bound for embedded hardware to directly compute the time differential of the arriving signals using the time-to-digital converter(TDC).The results of the experiments show that the errors are controlled when the positioning algorithm is applied in various complicated situations to fulfill the requirements of engineering applications.The statistical analysis of the data reveals that the proposed UWB RTLS auto-positioning system can track target tags with an accuracy of 0.20 m.
文摘A novel approach for improving antenna bandwidth is described using a 6-element Yagi-Uda array as an example. The new approach applies Central Force Optimization, a deterministic metaheuristic, and Variable Z0 technology, a novel, proprietary design and optimization methodology, to produce an array with 33.09% fractional impedance bandwidth. This array’s performance is compared to its CFO-optimized Fixed Z0counterpart, and to the performance of a 6-ele- ment Dominating Cone Line Search-optimized array. Both CFO-optimized antennas exhibit better performance than the DCLS array, especially with respect to impedance bandwidth. Although the Yagi-Uda antenna was chosen to illustrate this new approach to antenna design and optimization, the methodology is entirely general and can be applied to any antenna against any set of performance objectives.
基金supported by National Natural Science Fundation of China (61271201)the Fundamental Research Funds for the Central Universities of China (W12JB00060 and 2013JBM016)
文摘Due to its large bandwidth and the complexity of indoor environment, the ultra-wideband （UWB） channel is frequency selective, which affects the data rate and reliability of UWB communication. This paper investigates amplify-and-forward （AF） relay scheme to mitigate this reliability problem for orthogonal frequency division multiplexing （OFDM）-UWB communication. The relay can be used to acquire capacity gain and diversity gain just like multiple-input and multiple-output （MIMO） system. The first investigation focuses on the relay-node selection criterion and combination ratio for capacity gain. Capacity gain depends on the correlation of frequency responses between direct link and relay link in addition to signal-to-noise ratio （SNR） of relay link. Increased similarity of the two frequency responses increases capacity gain. Capacity gain＇s best relay and combination ratio are found by taking the derivative of the capacity equation. Solution of the quadratic derivative equation of ratio finds the optimal ratios for every potential relay node. The second investigation focuses on relay-node selection criterion and combination ratio for diversity gain. Higher diversity gain corresponds to less deep-faded sub-channels of combined signal. Reduced computation divides the problem into two steps： the first step selects the relay node according to the criterion that is dependent on the expectation value and variance of S（f）--the function of SNR of Jq the second step solves the optimization problem for optimal combination ratio. Numerical simulation shows that our scheme is effective in pursuit of capacity gain and of diversity gain.
基金supported by the National High Technology Research and Development Program("863" Program)under Grant No.2007AA01Z264 and 2006AA01Z256the National Natural Science Foundation under Grant No.60736002 and 60702006
文摘The microwave photonic technology-based Ultra-Wideband (UWB) Radio over Fiber (RoF) system is an important solution to the future low-cost and high-performance ultra-wideband wireless access network.Much research work has been done in this field with abundant results.This article introduces the RoF system that is based on the all-optical vector modulation technology to further enhance signal’s spectrum efficiency;the full-duplex RoF system that is based on the millimeter wave Phase-Shift Keying (PSK) modulation to greatly simplify base station structure and fiber layout;and the RoF system that is based on multi-service mixed transmission to carry the service with both wired signal and several wireless signals.The article also presents an RoF-based high-definition video transmission platform.
基金financially supported by the National Science Funds for Excellent Young Scholars of China(No.61822106)the Natural Science Foundation of China(Nos.U19A2070,62074025)the National Key Research&Development Program(No.2020YFA0309200)。
文摘With the rapid development of science and technology,the emergence of new application scenarios,such as robots,driverless vehicles and smart city,puts forward high requirements for artificial visual systems.Optoelectronic synaptic devices have attracted much attention due to their advantages in sensing,memory and computing integration.In this work,via band structure engineering and heterostructure designing,a heterojunction optoelectronic synaptic device based on Cu doped with n-type SrTiO_(3)(Cu:STO)film combined with p-type CuAlO_(2)(CAO)thin film was fabricated.It is found surprisingly that the optoelectronic device based on Cu:STO/CAO p-n heterojunction exhibits a rapid response of 2 ms,and that it has a wideband response from visible to near-infrared(NIR)region.Additionally,a series of important synaptic functions,including excitatory postsynaptic current(EPSC),paired-pulse facilitation(PPF),shortterm potentiation(STP)to long-term potentiation(LTP)transition,learning experience behavior and image sharpening,have been successfully simulated on the device.More importantly,the performance of the device remains still stable and reliable after several months which were stored at room temperature and atmospheric pressure.Based on these advantages,the optoelectronic synaptic devices demonstrated here provide great potential in the new generation of artificial visual systems.
