The performance of the Noblesse multi-collector noble gas mass spectrometer for ^(40)Ar/^(39)Ar geochronology

Noblesse multi-collector noble gas mass spec- trometer is specially designed for multi-collection of Ar isotopes with different beam sizes, especially for small ion beams, precisely, and hence is perfectly suitable for ^40Ar/^39Ar geochronology. We have analyzed widely used sanidine, muscovite, and biotite standards with recom- mended ages of - 1.2-133 Ma, with the aim to assess the reliability of Noblesse for ^40Ar/^39Ar dating. An ESI MIR10 30W CO2 laser was used for total fusion or incremental heating samples. Extracted gases were routinely purified by four SAES NP10 getters （one at - 400 ℃ and others at room temperature）. A GP50 getter and a metal cold finger cooled by liquid N （- 196 ℃） were also attached for additional purification if necessary. The Ar isotopes were then measured by Noblesse using Faraday or multiplier according to the signal intensities. Over a period of 1.5 months 337 air calibrations produced a weighted mean ^40Ar/^36Ar of 296.50 ± 0.08 （2σ, MSWD = 4.77）. Fish Canyon sanidine is used to calculate J-values, which show good linear relationship with position in irradiation. The age of four mineral standards （Alder Creek sanidine, Brione muscovite, Yabachi sanidine, and Fangshan biotite） are within error of the accepted ages. Five Alder Creek sanidine aliquots yielded an age range of 1.174-1.181 ± 0.013 Ma （2σ） which broadly overlaps the established age of the standard and the uncertainty approaches those of the foremost Ar/Ar laboratories in the world. The weighted mean ages of four Brione muscovite aliquots （18.75 i 0.16 Ma, 2σ）, five Yabachi sanidine aliquots （29.50 ± 0.19 Ma, 2σ）, and three Fangshan bio- tite aliquots （133.0 ± 0.76 Ma, 2σ） are consistent with the recommended values of these standards, and the uncer- tainties are typical of modem Ar/Ar laboratories world- wide.

Dual-mode Nonlinear MPC via Terminal Control Laws With Free-parameters

The paper presents a new dual-mode nonlinear model predictive control(NMPC) scheme for continuous-time nonlinear systems subject to constraints on the state and control.The idea of control Lyapunov functions for nonlinear systems is used to compute the terminal regions and terminal control laws with some free-parameters in the dual-mode NMPC framework.The parameters of the terminal controller are selected offline to estimate the terminal region as large as possible;and the parameters are optimized online to gain optimality of the terminal controller with respect to given cost functions.Then a dual-mode NMPC algorithm with varying time-horizon is formulated for the constrained system.Recursive feasibility and closed-loop stability of this NMPC are established.The example of a spring-cart is used to demonstrate the advantages of the presented scheme by comparing to the dual-mode NMPC via the linear quadratic regulator(LQR) method.

通信拓扑切换下车辆队列分布式多目标预测控制

考虑存在通信拓扑切换的非线性车辆队列多目标编队控制问题,提出一种分布式多目标模型预测控制(multi-objective model predictive control,Mo-MPC)策略.首先,利用邻居车辆状态信息以及与时间相关的图函数构造队列协同控制目标函数,再使用字典序优化描述分布式Mo-MPC问题.然后,采用平均终端等式约束保证各车预测终端状态的收敛性.进一步结合权值矩阵充分条件和兼容性约束,利用切换系统公共Lyapunov稳定性技术保证车辆队列闭环系统的稳定性.同时,为了抑制前车状态误差波动沿着队列传播,使用一类状态误差最大值约束保证车辆队列的L∞弦稳定性.最后,利用两组典型工况的对比仿真结果验证本文策略较传统编队控制策略在经济性能方面的提升.

Dating Kimberlite Using Apatite U-Pb Geochronology: A Case Study from Diamond-Bearing Dikes in South China

Kimberlite,one of the deepest known magmatic rocks on Earth,offers valuable glimpses into the deep mantle composition(Woodhead et al.,2019),craton structure(Gardiner et al.,2020),global geodynamic variation(Tappe et al.,2018),and diamond formation(Giuliani et al.,2023).The accurate determination of the emplacement of this special rock is crucial for revealing such information.However,dating kimberlite is challenging due to its silica-poor,volatile-rich,strongly altered,and hybrid nature(Mitchell et al.,2019).Zircon is unsuitable for dating kimberlite and related rocks due to its preference for crystallizing in intermediate to felsic melts(Gervasoni et al.,2016)rather than silica-poor ones.Even if present,zircon is prone to Pb loss through hydrothermal alteration(Zi et al.,2022)in a volatile-rich system like kimberlitic magmas.

Constrained nonlinear MPC for accelerated tracking piece-wise references and its applications to thermal systems

In this paper,we propose a model predictive control(MPC)strategy for accelerated offset-free tracking piece-wise constant reference signals of nonlinear systems subject to state and control constraints.Some special contractive constraints on tracking errors and terminal constraints are embedded into the tracking nonlinear MPC formulation.Then,recursive feasibility and closed-loop convergence of the tracking MPC are guaranteed in the presence of piece-wise references and constraints by deriving some sufficient conditions.Moreover,the local optimality of the tracking MPC is achieved for unreachable output reference signals.By comparing to traditional tracking MPC,the simulation experiment of a thermal system is used to demonstrate the acceleration ability and the effectiveness of the tracking MPC scheme proposed here.

Energy-efficient receding horizon trajectory planning of high-speed trains using real-time traffic information

Optimal trajectory planning of high-speed trains(HSTs)aims to obtain such speed curves that guarantee safety,punctuality,comfort and energy-saving of the train.In this paper,a new shrinking horizon model predictive control(MPC)algorithm is proposed to plan the optimal trajectories of HSTs using real-time traffic information.The nonlinear longitudinal dynamics of HSTs are used to predict the future behaviors of the train and describe variable slopes and variable speed limitations based on real-time traffic information.Then optimal trajectory planning of HSTs is formulated as the shrinking horizon optimal control problem with the consideration of safety,punctuality,comfort and energy consumption.According to the real-time position and running time of the train,the shrinking horizon is updated to ensure the recursive feasibility of the optimization problem.The optimal speed curve of the train is computed by online solving the optimization problem with the Radau Pseudo-spectral method(RPM).Simulation results demonstrate that the proposed method can satisfy the requirements of energy efficiency and punctuality of the train.