Binary Offset Carrier(BOC) has been chosen as one of modulation methods in the future Global Navigation Satellite Systems(GNSS). Even though BOC signals can bring several advantages such as better track performance an...Binary Offset Carrier(BOC) has been chosen as one of modulation methods in the future Global Navigation Satellite Systems(GNSS). Even though BOC signals can bring several advantages such as better track performance and higher positioning accuracy, there is a drawback that the autocorrelation functions have multiple side-peaks if BOC modulation is adopted. This characteristic will lead to false acquisition and the tracking loop will be locked in false phase point. The proposed Correlation Combination Ambiguity Removing Technology(CCART) cancelled all the side-peaks of the sine-phased BOC(kn,n) signals completely by making use of two kinds of correlation functions. Two kinds of sub-correlation functions were combined separately and then final correlation function without side-peaks was acquired. The simulation results are given and compared with other techniques. It is shown that acquisition will not be degraded with the increase of k.展开更多
In this paper,we investigate a leader-following tracking problem for multi-agent systems with boundedinputs.We propose a distributed bounded protocol for each follower to track a leader whose states may not be complet...In this paper,we investigate a leader-following tracking problem for multi-agent systems with boundedinputs.We propose a distributed bounded protocol for each follower to track a leader whose states may not be completelymeasured.We theoretically prove that each agent can follow the leader with estimable track errors.Finally,somenumerical simulations are presented to illustrate our theoretical results.展开更多
This paper proposes a new coordination method for multi-robot system.The state space for a multi-robot system is constructed according to the task requirements and system characteristics.Reachable statefor the system ...This paper proposes a new coordination method for multi-robot system.The state space for a multi-robot system is constructed according to the task requirements and system characteristics.Reachable statefor the system is constrained by the system s internal and external constraints,under which the task isexecutable if there exists a state transition trajectory from the initial to the goal state in its state space.Ifthe task is realizable,the feasible or the optimal strategy for task execution could then be investigated inthe state space.Otherwise,the task could be modified to be realizable via adjusting system s configura-tions and/or task constraints,which provides critical guidance for system reconstructions.This con-tributes to the designing and planning of the robotic tasks.Experiments of multi-robot formation movementare conducted to show the validity of the proposed method.展开更多
The BEPC RF system has been changed to superconducting cavities during the last four years.In the Summer of 2006,the high power test had been successfully carried.In November,the East RF was put into commis- sioning.T...The BEPC RF system has been changed to superconducting cavities during the last four years.In the Summer of 2006,the high power test had been successfully carried.In November,the East RF was put into commis- sioning.The SRF system above 1.0MV voltage has been reached with the e^+/e^- collision beam over 100mA,and the beam current improved to 2.5GeV/250mA with 100kW beam power.The beam test shows the good matching of the RF parameters with measuring value and theoretic calculation.The commissioning and the high power test will be presented in this paper.展开更多
We study the optimal quantum control of heteronuclear two-qubit systems described by a Hamiltonian containing both nonlocal internal drift and local control terms.We derive an explicit formula to compute the minimum t...We study the optimal quantum control of heteronuclear two-qubit systems described by a Hamiltonian containing both nonlocal internal drift and local control terms.We derive an explicit formula to compute the minimum time required to steer the system from an initial state to a specified final state.As applications the minimal time to implement Controlled-NOT gate,SWAP gate and Controlled-U gate is calculated in detail.The experimental realizations of these quantum gates are explicitly presented.展开更多
Signal structure design is an important part of satellite navigation system research,which directly affects navigation performance.Signal performance parameters are analyzed and performances of BPSK modulated signals ...Signal structure design is an important part of satellite navigation system research,which directly affects navigation performance.Signal performance parameters are analyzed and performances of BPSK modulated signals and BOC modulated signals are compared.Aiming at requirements of high navigation precision and high anti-jamming ability,a new navigation signal structure based on complex carrier modulation is proposed and performances of the signal are researched with different parameters.A synchronization algorithm is put forward according to the signal characteristics,and the synchronization performance is qualitatively analyzed.Next,the applications of the complex carrier modulated signal are discussed,which include anti-jamming,navigation enhancement,power combing and so on.Simulations and analysis show that the proposed navigation signal structure based on complex carrier modulation has good navigation capabilities and anti-jamming abilities,which deserves further study.展开更多
By adopting a distributed feedback laser(DFBL) centered at 1.654 μm, a near-infrared(NIR) methane(CH4) detection system based on tunable diode laser absorption spectroscopy(TDLAS) is experimentally demonstrated. A la...By adopting a distributed feedback laser(DFBL) centered at 1.654 μm, a near-infrared(NIR) methane(CH4) detection system based on tunable diode laser absorption spectroscopy(TDLAS) is experimentally demonstrated. A laser temperature control as well as wavelength modulation module is developed to control the laser's operation temperature. The laser's temperature fluctuation can be limited within the range of-0.02—0.02 °C, and the laser's emitting wavelength varies linearly with the temperature and injection current. An open reflective gas sensing probe is realized to double the absorption optical path length from 0.2 m to 0.4 m. Within the detection range of 0—0.01, gas detection experiments were conducted to derive the relation between harmonic amplitude and gas concentration. Based on the Allan deviation at an integral time of 1 s, the limit of detection(Lo D) is decided to be 2.952×10^(-5) with a path length of 0.4 m, indicating a minimum detectable column density of ~1.2×10^(-5) m. Compared with our previously reported NIR CH_4 detection system, this system exhibits some improvement in both optical and electrical structures, including the analogue temperature controller with less software consumption, simple and reliable open reflective sensing probe.展开更多
基金supported in part by National Natural Science Foundation of China under Grant No.61372110National High Technology Research and Development Program of China (863 Program) under Grant No. 2012AA120802
文摘Binary Offset Carrier(BOC) has been chosen as one of modulation methods in the future Global Navigation Satellite Systems(GNSS). Even though BOC signals can bring several advantages such as better track performance and higher positioning accuracy, there is a drawback that the autocorrelation functions have multiple side-peaks if BOC modulation is adopted. This characteristic will lead to false acquisition and the tracking loop will be locked in false phase point. The proposed Correlation Combination Ambiguity Removing Technology(CCART) cancelled all the side-peaks of the sine-phased BOC(kn,n) signals completely by making use of two kinds of correlation functions. Two kinds of sub-correlation functions were combined separately and then final correlation function without side-peaks was acquired. The simulation results are given and compared with other techniques. It is shown that acquisition will not be degraded with the increase of k.
基金Supported by the National Science Foundation of China under Grant Nos.10702023,10832006,and 60704041the Research Fund for the Doctoral Program of Higher Education under Grant No.20070487090
文摘In this paper,we investigate a leader-following tracking problem for multi-agent systems with boundedinputs.We propose a distributed bounded protocol for each follower to track a leader whose states may not be completelymeasured.We theoretically prove that each agent can follow the leader with estimable track errors.Finally,somenumerical simulations are presented to illustrate our theoretical results.
基金Supported by the National Natural Science Foundation for Distinguished Young Scholars Abroad (No. 60428303)
文摘This paper proposes a new coordination method for multi-robot system.The state space for a multi-robot system is constructed according to the task requirements and system characteristics.Reachable statefor the system is constrained by the system s internal and external constraints,under which the task isexecutable if there exists a state transition trajectory from the initial to the goal state in its state space.Ifthe task is realizable,the feasible or the optimal strategy for task execution could then be investigated inthe state space.Otherwise,the task could be modified to be realizable via adjusting system s configura-tions and/or task constraints,which provides critical guidance for system reconstructions.This con-tributes to the designing and planning of the robotic tasks.Experiments of multi-robot formation movementare conducted to show the validity of the proposed method.
文摘The BEPC RF system has been changed to superconducting cavities during the last four years.In the Summer of 2006,the high power test had been successfully carried.In November,the East RF was put into commis- sioning.The SRF system above 1.0MV voltage has been reached with the e^+/e^- collision beam over 100mA,and the beam current improved to 2.5GeV/250mA with 100kW beam power.The beam test shows the good matching of the RF parameters with measuring value and theoretic calculation.The commissioning and the high power test will be presented in this paper.
基金supported by the National Natural Science Foundation of China(Grant No.11275131)the National Research Foundation for the Doctoral Program of Higher Education of China
文摘We study the optimal quantum control of heteronuclear two-qubit systems described by a Hamiltonian containing both nonlocal internal drift and local control terms.We derive an explicit formula to compute the minimum time required to steer the system from an initial state to a specified final state.As applications the minimal time to implement Controlled-NOT gate,SWAP gate and Controlled-U gate is calculated in detail.The experimental realizations of these quantum gates are explicitly presented.
文摘Signal structure design is an important part of satellite navigation system research,which directly affects navigation performance.Signal performance parameters are analyzed and performances of BPSK modulated signals and BOC modulated signals are compared.Aiming at requirements of high navigation precision and high anti-jamming ability,a new navigation signal structure based on complex carrier modulation is proposed and performances of the signal are researched with different parameters.A synchronization algorithm is put forward according to the signal characteristics,and the synchronization performance is qualitatively analyzed.Next,the applications of the complex carrier modulated signal are discussed,which include anti-jamming,navigation enhancement,power combing and so on.Simulations and analysis show that the proposed navigation signal structure based on complex carrier modulation has good navigation capabilities and anti-jamming abilities,which deserves further study.
基金supported by the National Key Technology R&D Program of China(Nos.2013BAK06B04 and 2014BAD08B03)the National Natural Science Foundation of China(Nos.61307124 and 11404129)+3 种基金the Science and Technology Department of Jilin Province of China(Nos.20120707 and 20140307014SF)the Changchun Municipal Science and Technology Bureau(Nos.11GH01 and 14KG022)the State Key Laboratory on Integrated OptoelectronicsJilin University(No.IOSKL2012ZZ12)
文摘By adopting a distributed feedback laser(DFBL) centered at 1.654 μm, a near-infrared(NIR) methane(CH4) detection system based on tunable diode laser absorption spectroscopy(TDLAS) is experimentally demonstrated. A laser temperature control as well as wavelength modulation module is developed to control the laser's operation temperature. The laser's temperature fluctuation can be limited within the range of-0.02—0.02 °C, and the laser's emitting wavelength varies linearly with the temperature and injection current. An open reflective gas sensing probe is realized to double the absorption optical path length from 0.2 m to 0.4 m. Within the detection range of 0—0.01, gas detection experiments were conducted to derive the relation between harmonic amplitude and gas concentration. Based on the Allan deviation at an integral time of 1 s, the limit of detection(Lo D) is decided to be 2.952×10^(-5) with a path length of 0.4 m, indicating a minimum detectable column density of ~1.2×10^(-5) m. Compared with our previously reported NIR CH_4 detection system, this system exhibits some improvement in both optical and electrical structures, including the analogue temperature controller with less software consumption, simple and reliable open reflective sensing probe.
