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This paper initially constructs a model between coal mine safety regulation and the responding behavior of workers and business. Through the model, it analyzes the trade-offs between safety-and market-oriented products, and reveal...
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This paper initially constructs a model between coal mine safety regulation and the responding behavior of workers and business. Through the model, it analyzes the trade-offs between safety-and market-oriented products, and reveals the inhibitory effect of safety regulation on production efficiency of the industry. It puts forward and gives the definitions of "dominant moral hazard" and "partial moral hazard" respectively. On this basis, the paper conducts an empirical study of the effects of China's coal mine safety regulation on workers and business behavior. The results show that China's coal mine safety regulation actually reduces the efficiency of coal production, consistent with the theoretical reasoning and proposition that there exist obvious "partial moral hazard" problems in coal mine safety regulation, which should arouse the attention of the parties concerned.Finally, it makes concluding remarks and puts forward some points for further exploration.
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摘要 :
This paper initially constructs a model between coal mine safety regulation and the responding behavior of workers and business. Through the model, it analyzes the trade-offs between safety-and market-oriented products, and reveal...
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This paper initially constructs a model between coal mine safety regulation and the responding behavior of workers and business. Through the model, it analyzes the trade-offs between safety-and market-oriented products, and reveals the inhibitory effect of safety regulation on production efficiency of the industry. It puts forward and gives the definitions of "dominant moral hazard" and "partial moral hazard" respectively. On this basis, the paper conducts an empirical study of the effects of China's coal mine safety regulation on workers and business behavior. The results show that China's coal mine safety regulation actually reduces the efficiency of coal production, consistent with the theoretical reasoning and proposition that there exist obvious "partial moral hazard" problems in coal mine safety regulation, which should arouse the attention of the parties concerned.Finally, it makes concluding remarks and puts forward some points for further exploration.
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First,unscented Kalman filter parameter estimation method is proposed to solve the optimal low-thrust transfer problem to Geostationary Orbit.Due to operational constraints of attitude control actuators and uncertain perturbations...
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First,unscented Kalman filter parameter estimation method is proposed to solve the optimal low-thrust transfer problem to Geostationary Orbit.Due to operational constraints of attitude control actuators and uncertain perturbations, a robust closed-loop guidance scheme of constant low-thrust is implemented .The essential idea of the guidance law is to decouple the original multiple revolution optimal control problem into a sequence of trajectory tracking problem in one revolution. Analytical equations are deduced under the condition of continuous constant acceleration. Using these equations, taken the node times of the thrust arcs and the attitude of the thrust as variables, the trajectory tracking problem in one revolution is transformed into an optimization problem with the nonlinear constraints of minimum attitude maneuver time and the consistency of attitude. Finally the whole trajectory optimization approach developed in the paper is applied to low thrust GTO-GEO transfer design, the results show that the tracking error and boundary error are very small.
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摘要 :
First,unscented Kalman filter parameter estimation method is proposed to solve the optimal low-thrust transfer problem to Geostationary Orbit.Due to operational constraints of attitude control actuators and uncertain perturbations...
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First,unscented Kalman filter parameter estimation method is proposed to solve the optimal low-thrust transfer problem to Geostationary Orbit.Due to operational constraints of attitude control actuators and uncertain perturbations, a robust closed-loop guidance scheme of constant low-thrust is implemented .The essential idea of the guidance law is to decouple the original multiple revolution optimal control problem into a sequence of trajectory tracking problem in one revolution. Analytical equations are deduced under the condition of continuous constant acceleration. Using these equations, taken the node times of the thrust arcs and the attitude of the thrust as variables, the trajectory tracking problem in one revolution is transformed into an optimization problem with the nonlinear constraints of minimum attitude maneuver time and the consistency of attitude. Finally the whole trajectory optimization approach developed in the paper is applied to low thrust GTO-GEO transfer design, the results show that the tracking error and boundary error are very small.
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In order to meet the requirements of spacecraft fly-around technology in on-orbit service mission, spacecraft forced fly-around trajectory design and control scheme is investigated. Based on the analytic solution of the C-W equati...
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In order to meet the requirements of spacecraft fly-around technology in on-orbit service mission, spacecraft forced fly-around trajectory design and control scheme is investigated. Based on the analytic solution of the C-W equations, four fly-around trajectories are designed, including bi-elliptic, teardrop, bi-teardrop, multi-impulse fly-around based on nominal trajectory. The formula between initial states of following spacecraft and the shape of fly-around trajectory is derived, and the analytic expressions of four fly-around trajectories and the impulse control scheme are proposed. Simulation results verify that four trajectories designed could be used in spacecraft slow fly-around and fast fly-around. The velocity consumptions of different trajectories with fly-around period are compared. The theory of spacecraft forced fly-around trajectory design and control is improved, and the results provide reference for engineering application.
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摘要 :
In order to meet the requirements of spacecraft fly-around technology in on-orbit service mission, spacecraft forced fly-around trajectory design and control scheme is investigated. Based on the analytic solution of the C-W equati...
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In order to meet the requirements of spacecraft fly-around technology in on-orbit service mission, spacecraft forced fly-around trajectory design and control scheme is investigated. Based on the analytic solution of the C-W equations, four fly-around trajectories are designed, including bi-elliptic, teardrop, bi-teardrop, multi-impulse fly-around based on nominal trajectory. The formula between initial states of following spacecraft and the shape of fly-around trajectory is derived, and the analytic expressions of four fly-around trajectories and the impulse control scheme are proposed. Simulation results verify that four trajectories designed could be used in spacecraft slow fly-around and fast fly-around. The velocity consumptions of different trajectories with fly-around period are compared. The theory of spacecraft forced fly-around trajectory design and control is improved, and the results provide reference for engineering application.
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Carrier-phase differential global positioning system techniques have been playing an increasingly important role in high-precision spacecraft relative navigation. In kinematic spacecraft relative navigation data processing, algori...
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Carrier-phase differential global positioning system techniques have been playing an increasingly important role in high-precision spacecraft relative navigation. In kinematic spacecraft relative navigation data processing, algorithms are usually based on the least-squares principle for which both functional and stochastic models are always involved. Proper stochastic model estimation is of relevance for the choice of observation weights, which allows one to specify by how much the individual observation should contribute to the overall solution. In the present contribution, a more realistic stochastic model of GPS observations for LEO relative navigation applications is formulated. This model presents the double-differencing introduced correlation between different channels, as well as the correlation between different observation types and the temporal correlation. This GPS observations stochastic model is presented in a form of covariance matrix which has been written as an unknown linear combination of known cofactor matrices. The coeffcients of this linear combination are then assessed by an iterated Least Square estimator. The effciency of this estimator is investigated using truth-model simulation data of two formation satellites. Test results indicate that the precision of the estimated positioning is improved by applying the proposed stochastic model and assessment procedure. In addition, the speed to fix the interger ambiguity can be suffciently improved.
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摘要 :
Carrier-phase differential global positioning system techniques have been playing an increasingly important role in high-precision spacecraft relative navigation. In kinematic spacecraft relative navigation data processing, algori...
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Carrier-phase differential global positioning system techniques have been playing an increasingly important role in high-precision spacecraft relative navigation. In kinematic spacecraft relative navigation data processing, algorithms are usually based on the least-squares principle for which both functional and stochastic models are always involved. Proper stochastic model estimation is of relevance for the choice of observation weights, which allows one to specify by how much the individual observation should contribute to the overall solution. In the present contribution, a more realistic stochastic model of GPS observations for LEO relative navigation applications is formulated. This model presents the double-differencing introduced correlation between different channels, as well as the correlation between different observation types and the temporal correlation. This GPS observations stochastic model is presented in a form of covariance matrix which has been written as an unknown linear combination of known cofactor matrices. The coeffcients of this linear combination are then assessed by an iterated Least Square estimator. The effciency of this estimator is investigated using truth-model simulation data of two formation satellites. Test results indicate that the precision of the estimated positioning is improved by applying the proposed stochastic model and assessment procedure. In addition, the speed to fix the interger ambiguity can be suffciently improved.
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An S band narrowband bandpass filter BAW with center frequency 2.460 GHz, bandwidth 41MHz, band insertion loss -1.154 dB, the passband ripple 0.9 dB, the out of band rejection about -42.5dB@2.385 GHz; -45.5dB@2.506 GHz was designe...
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An S band narrowband bandpass filter BAW with center frequency 2.460 GHz, bandwidth 41MHz, band insertion loss -1.154 dB, the passband ripple 0.9 dB, the out of band rejection about -42.5dB@2.385 GHz; -45.5dB@2.506 GHz was designed for potential UAV measurement and control applications. According to the design specifications, the design is as follows: each FBAR's stack was designed in BAW filter by using Mason model. Each FBAR's shape was designed with the method of apodization electrode. The layout of BAW filter was designed. The acoustic-electromagnetic co-simulation model was built to validate the performance of the designed BAW filter. The presented design procedure is a common one, and there are two characteristics: 1) an A&EM co-simulation method is used for the final BAW filter performance validation in the design stage, thus ensures over-optimistic designs by the bare 1D Mason model are found and rejected in time; 2) An in-house developed auto-layout method is used to get compact BAW filter layout, which simplifies iterative error-and-try work here and output necessary in-plane geometry information to the A&EM co-simulation model.
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摘要 :
An S band narrowband bandpass filter BAW with center frequency 2.460 GHz, bandwidth 41MHz, band insertion loss -1.154 dB, the passband ripple 0.9 dB, the out of band rejection about -42.5dB@2.385 GHz; -45.5dB@2.506 GHz was designe...
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An S band narrowband bandpass filter BAW with center frequency 2.460 GHz, bandwidth 41MHz, band insertion loss -1.154 dB, the passband ripple 0.9 dB, the out of band rejection about -42.5dB@2.385 GHz; -45.5dB@2.506 GHz was designed for potential UAV measurement and control applications. According to the design specifications, the design is as follows: each FBAR's stack was designed in BAW filter by using Mason model. Each FBAR's shape was designed with the method of apodization electrode. The layout of BAW filter was designed. The acoustic-electromagnetic co-simulation model was built to validate the performance of the designed BAW filter. The presented design procedure is a common one, and there are two characteristics: 1) an A&EM co-simulation method is used for the final BAW filter performance validation in the design stage, thus ensures over-optimistic designs by the bare 1D Mason model are found and rejected in time; 2) An in-house developed auto-layout method is used to get compact BAW filter layout, which simplifies iterative error-and-try work here and output necessary in-plane geometry information to the A&EM co-simulation model.
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