It was 7 o’clock on November 17, 2001. Chen Qinglong, a hired driver in Dongguan City, Guangdong Province, was driving his vehicle to the checkpoint at Changping town of the city. A security guard of the town’s publ...It was 7 o’clock on November 17, 2001. Chen Qinglong, a hired driver in Dongguan City, Guangdong Province, was driving his vehicle to the checkpoint at Changping town of the city. A security guard of the town’s public security bureau blocked his way on the pretext that "his vehicle bumped into a security guard and injured him a few days ago." Then, a policeman from a sub-police station in Changping Town took Chen and his vehicle to the sub-police station.展开更多
A common folk can sue an official? This was hardly possible in the past in China where the old feudalistic tradition dies hard. But this is really possible today when the common people cannot only sue officials and al...A common folk can sue an official? This was hardly possible in the past in China where the old feudalistic tradition dies hard. But this is really possible today when the common people cannot only sue officials and also get compensation if they are wronged. State compensation system It would be inevitable for government functionaries to cause damages to some citizens, legal persons or other organizations in the course of their management of the society. That is why China has established a State compensation system to compensate for the damages to citizens, legal persons and other organizations caused by government functionaries in exercising their power.展开更多
Long-distance entanglement distribution is fundamental to the establishment of a large-scale quantum network,particularly in systems that operate without the need for trusted relays.Here,we demonstrate entanglement-ba...Long-distance entanglement distribution is fundamental to the establishment of a large-scale quantum network,particularly in systems that operate without the need for trusted relays.Here,we demonstrate entanglement-based quantum key distribution over 343 km of fiber spools using multi-wavelength single-photon-level calibration light for reference frame alignment.By co-propagating calibration and entangled photons through identical paths and sharing detectors in a time-multiplexed manner,a polarization purity of 2783 achieves for two mutually unbiased bases.The system operates continuously for 27.1 h in the laboratory,generating a total of 253 bits secure key at an asymptotic secure key rate of 3.68×10^(−3)bps.This work provides a viable approach for constructing large-scale quantum network.展开更多
Load simulator is a key test equipment for aircraft actuation systems in hardware-in-the-loop-simulation. Static loading is an essential function of the load simulator and widely used in the static/dynamic stiffness t...Load simulator is a key test equipment for aircraft actuation systems in hardware-in-the-loop-simulation. Static loading is an essential function of the load simulator and widely used in the static/dynamic stiffness test of aircraft actuation systems. The tracking performance of the static loading is studied in this paper. Firstly, the nonlinear mathematical models of the hydraulic load simulator are derived, and the feedback linearization method is employed to construct a feed-forward controller to improve the force tracking performance. Considering the effect of the friction, a LuGre model based friction compensation is synthesized, in which the unmeasurable state is estimated by a dual state observer via a controlled learning mechanism to guarantee that the estimation is bounded. The modeling errors are attenuated by a well-designed robust controller with a control accuracy measured by a design parameter. Employing the dual state observer is to capture the different effects of the unmeasured state and hence can improve the friction compensation accuracy. The tracking performance is summarized by a derived theorem. Experimental results are also obtained to verify the high performance nature of the proposed control strategy.展开更多
One of the major difficulties blocking China＇s path to becoming a developed capital market is the “state share overhang” problem that hampers the development of the stock market. With almost two-thirds of the outst...One of the major difficulties blocking China＇s path to becoming a developed capital market is the “state share overhang” problem that hampers the development of the stock market. With almost two-thirds of the outstanding shares of the stock market owned by the central government, investors are wary of the potential sell-off by the government that would inevitably dilute the value of their stock holdings. In this paper, we review the state share reform that aims at solving the dilemma that the central government faces： releasing billions of dollars of government＇s capital locked up in the nontradable stocks of the state-owned enterprises （SOEs） without suppressing the stock prices. We also discuss the alternative of using exchange traded funds （ETFs） as a complementary means to expediting the state share conversion process.展开更多
This paper presents new methods for spacecraft relative pose estimation using the Unscented Kalman Filter(UKF),taking into account non-additive process and measurement noises.A twistor model is employed to represent t...This paper presents new methods for spacecraft relative pose estimation using the Unscented Kalman Filter(UKF),taking into account non-additive process and measurement noises.A twistor model is employed to represent the spacecraft's relative 6-DOF motion of the chaser with respect to the target,expressed in the chaser body frame.The twistor model utilizes Modified Rodrigues Parameters(MRPs)to represent attitude with a minimal number of parameters,eliminating the need for the normalization constraint that exists in the quaternion-based model.Additionally,it incorporates both relative position and attitude in a single model,addressing kinematic coupling of states and simplifying the estimator design.Despite numerous existing pose estimation algorithms,many rely on the simplification of additive noise assumptions.This work enhances the robustness and improves the convergence of non-additive noise algorithms by deriving two methods to accurately approximate process and measurement noise covariance matrices for systems with non-additive noises.The first method utilizes the Stirling Interpolation Formula(SIF)to obtain equivalent process and measurement noise covariance matrices.The second method employs State Noise Compensation(SNC)to derive the equivalent process noise covariance matrix and uses SIF to compute the equivalent measurement noise covariance matrix.These methods are integrated into the UKF framework for estimating the relative pose of spacecraft in proximity operations,demonstrated through two scenarios:one with a cooperative target using Position Sensing Diodes(PSDs)and another with an uncooperative target using LiDAR for 3-D imaging.The effectiveness of these methods is validated against others in the literature through Monte Carlo simulations,showcasing their faster convergence and robust performance.展开更多
文摘It was 7 o’clock on November 17, 2001. Chen Qinglong, a hired driver in Dongguan City, Guangdong Province, was driving his vehicle to the checkpoint at Changping town of the city. A security guard of the town’s public security bureau blocked his way on the pretext that "his vehicle bumped into a security guard and injured him a few days ago." Then, a policeman from a sub-police station in Changping Town took Chen and his vehicle to the sub-police station.
文摘A common folk can sue an official? This was hardly possible in the past in China where the old feudalistic tradition dies hard. But this is really possible today when the common people cannot only sue officials and also get compensation if they are wronged. State compensation system It would be inevitable for government functionaries to cause damages to some citizens, legal persons or other organizations in the course of their management of the society. That is why China has established a State compensation system to compensate for the damages to citizens, legal persons and other organizations caused by government functionaries in exercising their power.
基金supported by the National Natural Science Foundation of China(Grant No.62171458)the Shenzhen Science and Technology Program(Grant No.JCYJ20220818102014029)the Science and Technology Innovation Program of Hunan Province(Grant No.2023RC3003).
文摘Long-distance entanglement distribution is fundamental to the establishment of a large-scale quantum network,particularly in systems that operate without the need for trusted relays.Here,we demonstrate entanglement-based quantum key distribution over 343 km of fiber spools using multi-wavelength single-photon-level calibration light for reference frame alignment.By co-propagating calibration and entangled photons through identical paths and sharing detectors in a time-multiplexed manner,a polarization purity of 2783 achieves for two mutually unbiased bases.The system operates continuously for 27.1 h in the laboratory,generating a total of 253 bits secure key at an asymptotic secure key rate of 3.68×10^(−3)bps.This work provides a viable approach for constructing large-scale quantum network.
基金National Science Fund for Distinguished Young Scholars (50825502)
文摘Load simulator is a key test equipment for aircraft actuation systems in hardware-in-the-loop-simulation. Static loading is an essential function of the load simulator and widely used in the static/dynamic stiffness test of aircraft actuation systems. The tracking performance of the static loading is studied in this paper. Firstly, the nonlinear mathematical models of the hydraulic load simulator are derived, and the feedback linearization method is employed to construct a feed-forward controller to improve the force tracking performance. Considering the effect of the friction, a LuGre model based friction compensation is synthesized, in which the unmeasurable state is estimated by a dual state observer via a controlled learning mechanism to guarantee that the estimation is bounded. The modeling errors are attenuated by a well-designed robust controller with a control accuracy measured by a design parameter. Employing the dual state observer is to capture the different effects of the unmeasured state and hence can improve the friction compensation accuracy. The tracking performance is summarized by a derived theorem. Experimental results are also obtained to verify the high performance nature of the proposed control strategy.
文摘One of the major difficulties blocking China＇s path to becoming a developed capital market is the “state share overhang” problem that hampers the development of the stock market. With almost two-thirds of the outstanding shares of the stock market owned by the central government, investors are wary of the potential sell-off by the government that would inevitably dilute the value of their stock holdings. In this paper, we review the state share reform that aims at solving the dilemma that the central government faces： releasing billions of dollars of government＇s capital locked up in the nontradable stocks of the state-owned enterprises （SOEs） without suppressing the stock prices. We also discuss the alternative of using exchange traded funds （ETFs） as a complementary means to expediting the state share conversion process.
基金the startup and UPAR grants funded by College of Engineering at United Arab Emirates University(UAEU).The grant codes are G00003527 and G00004562.
文摘This paper presents new methods for spacecraft relative pose estimation using the Unscented Kalman Filter(UKF),taking into account non-additive process and measurement noises.A twistor model is employed to represent the spacecraft's relative 6-DOF motion of the chaser with respect to the target,expressed in the chaser body frame.The twistor model utilizes Modified Rodrigues Parameters(MRPs)to represent attitude with a minimal number of parameters,eliminating the need for the normalization constraint that exists in the quaternion-based model.Additionally,it incorporates both relative position and attitude in a single model,addressing kinematic coupling of states and simplifying the estimator design.Despite numerous existing pose estimation algorithms,many rely on the simplification of additive noise assumptions.This work enhances the robustness and improves the convergence of non-additive noise algorithms by deriving two methods to accurately approximate process and measurement noise covariance matrices for systems with non-additive noises.The first method utilizes the Stirling Interpolation Formula(SIF)to obtain equivalent process and measurement noise covariance matrices.The second method employs State Noise Compensation(SNC)to derive the equivalent process noise covariance matrix and uses SIF to compute the equivalent measurement noise covariance matrix.These methods are integrated into the UKF framework for estimating the relative pose of spacecraft in proximity operations,demonstrated through two scenarios:one with a cooperative target using Position Sensing Diodes(PSDs)and another with an uncooperative target using LiDAR for 3-D imaging.The effectiveness of these methods is validated against others in the literature through Monte Carlo simulations,showcasing their faster convergence and robust performance.
