Tri-spin dynamics in alkali metal-noble gas NMR gyroscope

Alkali metal-noble gas NMR gyroscope is widely used for precision rotation measurement in fundamental and applied physics. By numerically simulating the alkali-nuclear-nuclear tri-spin dynamics, we investigate the dependence of gyroscope response on alkali spin relaxation time and nuclear spin magnetization. We found additional resonance peaks appear due to a new source of instability, namely the inherent multistability of tri-spin dynamics. The numerical simulation results agree well with the recent experiment, enabling a better understanding and exploitation of the gyroscope signal.Comment: 12 figure

Response Dynamics of Alkali Metal-Noble Gas Hybrid Trispin System

With numerical calculation of coupled Bloch equations, we have simulated the spin dynamics of nuclear magnetic resonance gyroscope based on alkali metal-noble gas hybrid trispin system. From the perspective of damping harmonic oscillator, a thorough analysis of the response dynamics is demonstrated. The simulation results shows a linear increasing response of gyroscope signal while the noblge gas nuclear spin magnetization and alkali atomic spin lifetime parameters are at the over damping condition. An upper limit of response is imposed on the NMR gyroscope signal due to the inherent dynamics of the hybrid trispin system. The results agrees with present available experimental results and provide useful guidings for future experiments.Comment: 5 pages, 3 figure

Soil and Water Conservation and Integrated Management in Watershed Ecosystem of the Loess Plateau, China

The Loess Plateau is well known for severe soil erosion and ecosystem degradation. The key issues in this region are the food security (grain), ecological security and a sustainable economy. This paper reviews a range of studies on ecological restoration, and management and the benefit at watershed scale on the Loess Plateau. This includes several successful cases and failures in soil conservation. The paper presents practical soil conservation measures and related benefit analysis, and discusses some effective methods adopted in soil erosion control, research directions and future perspectives for the Loess Plateau

Gravity Matching Aided Inertial Navigation Technique Based on Marginal Robust Unscented Kalman Filter

This paper is concerned with the topic of gravity matching aided inertial navigation technology using Kalman filter. The dynamic state space model for Kalman filter is constructed as follows: the error equation of the inertial navigation system is employed as the process equation while the local gravity model based on 9-point surface interpolation is employed as the observation equation. The unscented Kalman filter is employed to address the nonlinearity of the observation equation. The filter is refined in two ways as follows. The marginalization technique is employed to explore the conditionally linear substructure to reduce the computational load; specifically, the number of the needed sigma points is reduced from 15 to 5 after this technique is used. A robust technique based on Chi-square test is employed to make the filter insensitive to the uncertainties in the above constructed observation model. Numerical simulation is carried out, and the efficacy of the proposed method is validated by the simulation results

Research on Game of Manufacturer and Retailer Under Government’s Subsidy

Considering demand influenced by government’s subsidy, retail price, random factor, objective functions of maximizing expected profit are suggested to supplier and retailer, equilibrium solutions of supplier’s wholesale price, retailer’s retail price and order quantity are available based on Stackelberg game model, following conclusions are drawn by theoretical and numerical analysis, wholesale price, retail price, average demand, order quantity, profit increase with government’s subsidy; consumer’s expense price decreases with government’s subsidy. which means subsidy can boost demand, increase enterprise’s profit, reduce consumer’s cost, therefore, subsidy policy is favorable to government, enterprises and consumer. Key words: Government’s subsidy; Manufacturer; Retailer; Stackelberg gam

Gravity Matching Aided Inertial Navigation Technique Based on Marginal Robust Unscented Kalman Filter

This paper is concerned with the topic of gravity matching aided inertial navigation technology using Kalman filter. The dynamic state space model for Kalman filter is constructed as follows: the error equation of the inertial navigation system is employed as the process equation while the local gravity model based on 9-point surface interpolation is employed as the observation equation. The unscented Kalman filter is employed to address the nonlinearity of the observation equation. The filter is refined in two ways as follows. The marginalization technique is employed to explore the conditionally linear substructure to reduce the computational load; specifically, the number of the needed sigma points is reduced from 15 to 5 after this technique is used. A robust technique based on Chi-square test is employed to make the filter insensitive to the uncertainties in the above constructed observation model. Numerical simulation is carried out, and the efficacy of the proposed method is validated by the simulation results

Self-driven Hybrid Atomic Spin Oscillator

A self-driven hybrid atomic spin oscillator is demonstrated in theory and experiment with a vapor Rb-Xe dual-spin system. The raw signal of Rb spin oscillation is amplified, phase-shifted and sent back to drive the Xe spins coherently. By fine tuning the driving field strength and phase, a self-sustaining spin oscillation signal with zero frequency shift is obtained. The effective coherence time is infinitely prolonged beyond the intrinsic coherence time of Xe spins, forming a hybrid atomic spin oscillator. Spectral analysis indicates that a frequency resolution of 13.1 nHz is achieved, enhancing the detection sensitivity for magnetic field. Allan deviation analysis shows that the spin oscillator can operate in continuous wave mode like a spin maser. The prototype spin oscillator can be easily implanted into other hybrid spin systems and enhance the detection sensitivity of alkali metal-noble gas comagnetometers.Comment: 6 pages,5 figure