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A FAs approach for stabilization of generalized chained forms: part 1. Discontinuous control laws

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science China(Information sciences) 2024年第2期67卷 118-143页

作者： Guang-Ren duan Center for Control Theory and Guidance Technology Harbin Institute of Technology Center for Control science and Technology Southern University of Science and Technology

In this paper, a type of general nonholonomic systems is proposed, which contains both the Brockett’s two example systems, and their extended n-dimensional chained forms, as special cases. For the stabilization of such systems, a stabilizing controller is proposed based on the fully actuated system(FAs)approach, which is discontinuous at the origin but time-invariant when the open-loop system is time-invariant,and drives the feasible trajectories of the system to the origin exponentially. Furthermore, the proposed FAs approach is also extended to the sub-normal system case and the time-delay system case.

关键词： nonholonomic systems feedback stabilization exponential convergence sub-fully actuated systems time-delay systems

Probing the Bardeen-Kiselev black hole with the cosmological constant caused by Einstein equations coupled with nonlinear electrodynamics using quasinormal modes and greybody bounds

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Communications in Theoretical Physics 2024年第6期76卷 102-119页

作者： s R Wu B q Wang Z W Long College of Physics Guizhou UniversityGuiyang 550025China College Pharmacy Guizhou University of Traditional Chinese MedicineGuiyang 550025China

In this work,we investigate a static and spherically symmetric Bardeen-Kiselev black hole(BH)with the cosmological constant,which is a solution of the Einstein-non-linear Maxwell field *** compute the quasinormal frequencies for the Bardeen-Kiselev BH with the cosmological constant due to electromagnetic and gravitational *** varying the BH parameters,we discuss the behavior of both real and imaginary parts of the BH quasinormal frequencies and compare these frequencies with the Reissner-Nordström-de sitter BH surrounded by quintessence(RN-dsq).Interestingly,it is shown that the responses of the Bardeen-Kiselev BH with the cosmological constant and the RN-dsq under electromagnetic perturbations are different when the charge parameter q,the state parameter w and the normalization factor c are varied;however,for the gravitational perturbations,the responses of the Bardeen-Kiselev BH with the cosmological constant and the RN-dsq are different only when the charge parameter q is ***,compared with the gravitational perturbations,the electromagnetic perturbations can be used to understand nonlinear and linear electromagnetic fields in curved spacetime *** interesting observation is that,due to the presence of Kiselev quintessence,the electromagnetic perturbations around the Bardeen-Kiselev BH with the cosmological constant damps faster and oscillates slowly;for the gravitational perturbations,the quasinormal mode decays slowly and oscillates *** also study the reflection and transmission coefficients along with the absorption cross section in the Bardeen-Kiselev BH with the cosmological constant;it is shown that the transmission coefficients will increase due to the presence of Kiselev quintessence.

关键词： quasinormal modes greybody factors Bardeen-Kiselev black hole with cosmological constant

Electron kinetic effects in back-stimulated Raman scattering bursts driven by broadband laser pulses

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Matter and Radiation at Extremes 2024年第4期9卷 54-67页

作者： q.K.Liu L.Deng q.Wang X.Zhang F.q.Meng Y.P.Wang Y.q.Gao H.B.Cai s.P.Zhu Graduate school China Academy of Engineering PhysicsBeijing 100088China Institute of Applied Physics and Computational Mathematics Beijing 100094China school of Nuclear science and Technology University of Science and Technology of ChinaHefei 230026China shanghai Institute of Laser Plasma Shanghai 201800China HEDPs Center for Applied Physics and TechnologyPeking UniversityBeijing 100871China school of Physics Zhejiang UniversityHangzhou 310027China

We examine electron kinetic effects in broadband-laser-driven back-stimulated Raman scattering(BsRs)bursts using particle-in-cell *** bursts occur during the nonlinear stage,causing reflectivity spikes and generating large numbers of hot ***-duration simulations are performed to observe burst events,and a simplified model is developed to eliminate the interference of the broadband laser’s random intensity *** the simplified model,we isolate and characterize the spectrum of electron plasma *** spectrum changes from a sideband structure to a turbulence-like structure during the burst.A significant asymmetry in the spectrum is *** asymmetry is amplified and transferred to electron phase space by high-intensity broadband laser pulses,leading to violent vortex-merging and generation of hot *** proportion of hot electrons increases from 6.76%to 14.7%during a single violent burst *** demonstrate that kinetic effects profoundly influence the BsRs evolution driven by broadband lasers.

关键词： scattering kinetic simplified

Design Optimization and Operating Performance of s-CO_(2) Brayton Cycle under Fluctuating Ambient Temperature and Diverse Power Demand scenarios

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Journal of Thermal science 2024年第1期33卷 190-206页

作者： YANG Jingze YANG Zhen duan Yuanyuan Key Laboratory for Thermal science and Power Engineering of MOE Beijing Key Laboratory for CO_(2) Utilization and Reduction TechnologyTsinghua UniversityBeijing 100084China

The supercritical CO_(2)(s-CO_(2)) Brayton cycle is expected to replace steam cycle in the application of solar power tower system due to the attractive potential to improve efficiency and reduce *** the concentrated solar power plant with thermal energy storage is usually located in drought area and used to provide a dispatchable power output,the s-CO_(2) Brayton cycle has to operate under fluctuating ambient temperature and diverse power demand *** addition,the cycle design condition will directly affect the off-design *** this work,the combined effects of design condition,and distributions of ambient temperature and power demand on the cycle operating performance are analyzed,and the off-design performance maps are proposed for the first time.A cycle design method with feedback mechanism of operating performance under varied ambient temperature and power demand is introduced *** show that the low design value of compressor inlet temperature is not conductive to efficient operation under low loads and sufficient output under high ambient *** average yearly efficiency is most affected by the average power demand,while the load cover factor is significantly influenced by the average ambient *** multi-objective optimization,the optimal solution of designed compressor inlet temperature is close to the minimum value of35℃ in Delingha with low ambient temperature,while reaches 44.15℃ in Daggett under the scenario of high ambient temperature,low average power demand,long duration and large value of peak load during the peak temperature *** the cycle designed with compressor inlet temperature of 35℃ instead of 44.15℃ in Daggett under light industry power demand,the reduction of load cover factor will reach 0.027,but the average yearly efficiency can barely be improved.

关键词： supercritical CO_(2)Brayton cycle ambient temperature fluctuating power demand scenarios design optimization off-design performance

Exclusive Hypothesis Testing for Cox's Proportional Hazards Model

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Journal of systems science & Complexity 2024年第5期37卷 2157-2172页

作者： WU qiang TONG Xingwei duan Xiaogang school of statistics Beijing Normal University

Exclusive hypothesis testing is a new and special class of hypothesis testing. This kind of testing can be applied in survival analysis to understand the association between genomics information and clinical information about the survival time. Besides, it is well known that Cox's proportional hazards model is the most commonly used model for regression analysis of failure time. In this paper,the authors consider doing the exclusive hypothesis testing for Cox's proportional hazards model with right-censored data. The authors propose the comprehensive test statistics to make decision, and show that the corresponding decision rule can control the asymptotic Type Ⅰ errors and have good powers in theory. The numerical studies indicate that the proposed approach works well for practical situations and it is applied to a set of real data arising from Rotterdam Breast Cancer Data study that motivated this study.

关键词： Comprehensive test statistics Cox’s proportional hazards model exclusive hypothesis testing right-censored data Type I error

On Hamiltonian Property of Cayley Digraphs

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Acta Mathematicae Applicatae sinica 2024年第2期40卷 547-556页

作者： Fang duan qiong-xiang HUANG school of Mathematics science Xinjiang Normal UniversityUrumqi 830017China College of Mathematics and systems science Xinjiang UniversityUrumqi 830017China

Let G be a finite group generated by s and C(G,s) the Cayley digraphs of G with connection set *** this paper,we give some sufficient conditions for the existence of hamiltonian circuit in C(G,s),where G=Zm×H is a semiproduct of Zmby a subgroup H of *** particular,if m is a prime,then the Cayley digraph of G has a hamiltonian circuit unless G=Zm×*** addition,we introduce a new digraph operation,called φ-semiproduct of Γ1by Γ2and denoted by Γ1×Γ_φΓ2,in terms of mapping φ:V(Γ2)→{1,-1}.Furthermore we prove that C(Zm,{a})×_φ C(H,s) is also a Cayley digraph if φ is a homomorphism from H to{1,-1} ≤ Zm~*,which produces some classes of Cayley digraphs that have hamiltonian circuits.

关键词： Cayley digraphs hamiltonian circuit external semidirect product

High-throughput screening of single-atom catalysts confined in monolayer black phosphorus for efficient nitrogen reduction reaction

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Nano Research 2024年第4期17卷 2360-2367页

作者： Xiao-Yan Li Manyi duan Pengfei Ou Department of Electrical and Computer Engineering University of TorontoTorontoOntario M5S 1A4Canada school of Physics and Electronic Engineering Sichuan Normal UniversityChengdu 610101China Department of Chemistry Northwestern UniversityEvanstonIL 60208USA

The discovery of metal-nitrogen centers as the active sites for electrolysis has aroused significant interest in utilizing single-atom catalysts for nitrogen reduction reaction(NRR).Properly designed nanostructured catalysts that strongly interact with nitrogen molecules(N_(2))can promote adsorption and activation,thereby resulting in efficient catalysts with high stability,activity,and *** this study,using density functional theory calculations,we selected monolayer black phosphorus(BP)as the substrate and screened a series of single-atom transition metals confined in tri-coordinated and tetra-coordinated active centers(without and with N dopants)to electro-catalyze *** a result,we have identified two promising candidates(Hf_(1)-N_(1)P_(2)-1 and Tc_(1)-N_(4)),which exhibit not only low overpotentials of 0.56 and 0.49 V but also high thermodynamic and electrochemical stability,as well as good selectivity towards NRR over the competing hydrogen evolution *** also demonstrate the ability of Hf_(1)-N_(1)P_(2)-1 and Tc_(1)-N_(4) to activate and hydrogenate N_(2) by donating electrons and regulating charge *** study not only predicts new BP-based promising catalysts but also provides guidance for the rational design of high-performance NRR electrocatalysts under ambient conditions.

关键词： N_(2) electroreduction reaction single-atom catalysts black phosphorus density functional theory high-throughput calculations

An approach to estimate tree height using PolInsAR data constructed by the sentinel-1 dual-pol sAR data and RVoG model

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Journal of Electronic science and Technology 2024年第3期22卷 69-79页

作者： Yin Zhang Ding-Feng duan school of Resources and Environment University of Electronic Science and Technology of ChinaChengdu611731China

We estimate tree heights using polarimetric interferometric synthetic aperture radar(PolInsAR)data constructed by the dual-polarization(dual-pol)sAR data and random volume over the ground(RVoG)*** the sentinel-1 sAR dual-pol(sVV,vertically transmitted and vertically received and sVH,vertically transmitted and horizontally received)configuration,one notes that s_(HH),the horizontally transmitted and horizontally received scattering element,is *** s_(HH)data were constructed using the sVH data,and polarimetric sAR(PolsAR)data were *** proposed approach was first verified in simulation with satisfactory *** was next applied to construct PolInsAR data by a pair of dual-pol sentinel-1A data at Duke Forest,North Carolina,*** to local observations and forest descriptions,the range of estimated tree heights was overall *** the heights with the ICEsat-2 tree heights at 23 sampling locations,relative errors of 5 points were within±30%.Errors of 8 points ranged from 30%to 40%,but errors of the remaining 10 points were>40%.The results should be encouraged as error reduction is *** instance,the construction of PolsAR data should not be limited to using sVH,and a combination of sVH and sVV should be ***,an ensemble of tree heights derived from multiple PolInsAR data can be considered since tree heights do not vary much with time frame in months or one season.

关键词： Constructed polarimetric sAR data Dual polarization sentinel-1 sAR data Polarimetric interferometric sAR Random volume over the ground model Tree height estimation

Effects of acid deposition control in China:a review based on responses of subtropical forests

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Frontiers of Environmental science & Engineering 2024年第6期18卷 115-126页

作者： Danni Xie Xiaodong Ge Lei duan Jan Mulder school of Land Engineering Chang’an UniversityXi’an 710064China state Key Laboratory of Environmental simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China state Environmental Protection Key Laboratory of sources and Control of Air Pollution Complex Beijing 100084China Faculty of Environmental sciences and Natural Resource Management Norwegian University of Life SciencesBox 5003NO-1432ÅsNorway

For many decades,acid deposition used to pose a significant regional air pollution challenge in *** substantial emission control of anthropogenically derived sulfur and nitrogen containing gasses,both sulfur and nitrogen deposition,as well as the acid rain-affected area,have significantly decreased compared to their peak ***,particularly in the humid subtropics,are sensitive to acid deposition,as evidenced by soil acidification,sulfate and nitrate leaching in stream water,and elevated soil nitrous oxide *** in the total deposition of sulfur and nitrogen,caused a significant decline in sulfate and nitrate leaching from subtropical forest and subsequently in sulfate and nitrate concentrations in stream water,although there was about a 5-year *** delay may be attributed to the desorption of accumulated sulfate and continued elevated mineralization of accumulated nitrogen *** of nitrous oxide,a potent greenhouse gas,also declined in nitrogen-saturated subtropical forest soils,as soil water nitrate concentration ***,subtropical forests in China suffering from elevated acid deposition have begun to ***,the current levels of sulfur and nitrogen deposition continue to exceed the critical loads,i.e.,the assigned threshold levels in accordance with emission control policies,in more than 10%of the country’s land area,respectively,indicating remaining risks of acidification and ***,further emission reductions are urgently needed,also because they will help achieving goals related to air quality and nitrous oxide emissions.

关键词： Acidification Critical load Nitrous oxide surface water chemistry Recovery