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Identifiability and sloppiness of structured systems with a matrix fraction description using finite frequency responses

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Science China(Information Sciences) 2025年第2期68卷 200-215页

作者： Yunxiang MA tong zhou Department of Automation Tsinghua University Department of Automation and BNRist Tsinghua University

This paper investigates the identifiability of structured systems with a matrix fraction description and attacks practical difficulties in estimating parameters under finite frequency responses. The numerator and denominator polynomial matrices depend affinely on system parameters, which can represent a broad range of systems, especially circuits and mechanical systems. Except for assuming that the denominator matrix is invertible, no further assumptions are adopted. A criterion is provided for validating this assumption utilizing graph theories and matroids. A sufficient and necessary criterion for global identifiability based on the rank of a numerical matrix is given and can be recursively verified with each frequency point,which is computationally attractive for large-scale systems. For an identifiable system, an ellipsoid approximation is obtained for the set of parameters whose corresponding system frequency responses deviate within a specific range from those of the system at a specific parameter value. Using this approximation, explicit expressions for absolute and relative sloppiness have been derived, which can be used to quantify the difficulty of identifying system parameters. Comparisons with the well-known Fisher information matrix have also been performed through a mechanical system, revealing significant differences in quantifying parameter estimation hardness.

关键词： identifiability sloppiness structured system matrix fraction graph theory matroid

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Perspectives on additive manufacturing for warhead applications

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Defence Technology(防务技术) 2025年第1期43卷 225-251页

作者： Hao Xue Qiang zhou chuan Xiao Guangyan Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Ordnance Science and Research Academy of China Beijing 100089China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

According to different damage modes,warheads are roughly divided into three types:fragmentation warheads,shaped charge warheads,and penetrating *** to limitations in material and structural manufacturing,traditional manufacturing methods make it difficult to fully utilize the damage ability of the *** manufacturing(AM)technology can fabricate complex structures,with classified materials composition and customized components,while achieving low cost,high accuracy,and rapid production of the *** maturity of AM technology has brought about a new round of revolution in the field of *** this paper,we first review the principles,classifications,and characteristics of different AM *** development trends of AM technologies are pointed out,including multi-material AM technology,hybrid AM technology,and smart AM *** our survey,PBF,DED,and EBM technologies are mainly used to manufacture warhead damage *** and DIW technologies are mainly used to manufacture warhead ***,the research on the application of AM technology in three types of warhead and warhead charges was reviewed and the existing problems and progress of AM technologies in each warhead were ***,we summarized the typical applications and look forward to the application prospects of AM technology in the field of warheads.

关键词： Additive manufacturing Fragmentation warhead Shaped charge warhead Penetrating warhead Warhead charge

Magnitude, spatial patterns and drivers of methane fluxes from coastal salt marshes and mangrove forests in China

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Science China Earth Sciences 2025年第3期68卷 850-866页

作者： Yixuan YU Derrick Y.F.LAI Minjie HU chuan tong Key Laboratory of Humid Subtropical Eco-geographical Process of Ministry of Education Fujian Normal University School of Geographical Sciences Fujian Normal University Department of Geography and Resource Management The Chinese University of Hong Kong

Methane（CH4） is a highly potent greenhouse gas due to its high radiative forcing and global warming *** the magnitude, spatial patterns, and drivers of CH4emission from wetlands at the regional scale is crucial for formulating suitable strategies to mitigate future climate change. In this study, we synthesized the CH4flux data reported for major plant communities in the coastal salt marshes and mangrove forests in China and produced a spatial map of CH4fluxes from the mangrove sediments and salt marshes in China based on the results of machine learning models. Moreover, we examined the main drivers of CH4flux from these coastal wetlands and estimated the annual CH4emissions from the salt marshes and mangrove forests in different coastal provinces of China using a bottom-up approach. Our results showed that the mean CH4fluxes from the salt marsh and mangrove ecosystems in China were 2.22±0.29 and 2.26±0.55 mg m-2h-1, respectively. Across China, the total annual CH4emission from salt marshes was 31,179.75 Mg CH4a-1, while that from mangroves was 5,533.97 Mg CH4a-1with the sediments contributing to 12.7%(701.64 Mg CH4a-1) of the total efflux. The salt marshes and mangroves in China accounted for 2.75% and 0.14%–0.15% of the global annual CH4emissions from these two ecosystems,respectively. Moreover, we found that CH4emissions from the salt marshes and mangroves could offset the cooling impact arising from net carbon dioxide uptake by 88% and 53%, respectively, over a 100-year time scale. Mean annual temperature, soil moisture, and soil organic carbon content were the main factors controlling CH4emissions from these coastal ***, we found that CH4fluxes from the salt marshes in China decreased with latitude, which implied a possible increase in marsh CH4emission in response to global warming that should be considered carefully when developing nature-based climate solutions to achieve national goals for carbon neutrality.

关键词： Salt marsh Mangrove Methane flux Spatial pattern Driving factors China

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Development of a net ozone production rate detection system based on dual-channel cavity ring-down spectroscopy

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Journal of Environmental Sciences 2025年第3期149卷 419-430页

作者： Jinzhao tong Renzhi Hu Changjin Hu Xiaoyan Liu Haotian Cai chuan Lin Liujun Zhong JiaweiWang Pinhua Xie School of Environmental Science and Optoelectronic Technology University of Science and Technology of ChinaHefei 230026China Anhui Institute of Optics and Fine Mechanics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China School of Pharmacy Anhui Medical UniversityHefei 230032China

A novel system for measuring net photochemical ozone production rates in the atmosphere based on cavity ring-down spectroscopy(OPR-CRDS)was *** system consists of two chambers(a reaction chamber and a reference chamber)and a dual-channel O_(x)-CRDS *** minimize the wall loss of O_(x)in the chambers,the inner surfaces of both chambers are coated with Teflon *** performance of the OPR-CRDS system was *** was found that even though the photolysis frequency(J value)decreased by 10%,the decrease in the P(O_(3))caused by the ultraviolet-blocking film coating was less than 3%.The two chambers had a good consistency in the mean residence time and the measurement of NO_(2)and O_(x)under the condition of no *** detection limit of the OPR-CRDS was determined to be 0.20 ppbv/*** further verify the accuracy of the system,the direct measurement values of the OPR-CRDS systemwere comparedwith the calculation results based on radical(OH,HO_(2),and RO_(2))reactions,and a good correlation was obtained between the measured and calculated ***,the developed instrument was applied to obtain the comprehensive field observations at an urban site in the Yangtze River Delta(China)for 40 days,the time series and change characteristics of the P(O_(3))were obtained directly,and the good environmental adaptability and stability of the OPR-CRDS system were *** is expected that the new instrument will be beneficial to investigations of the relationship between P(O_(3))and its precursors.

关键词： Ozone Net photochemical production rate CRDS Atmospheric chemistry

Classifying extended,localized and critical states in quasiperiodic lattices via unsupervised learning

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Chinese Physics B 2025年第1期34卷 422-427页

作者： Bohan Zheng Siyu Zhu Xingping zhou tong Liu School of Computer Science and Technology School of SoftwareNanjing University of Posts and TelecommunicationsNanjing 210023China Institute of Quantum Information and Technology Nanjing University of Posts and TelecommunicationsNanjing 210003China Department of Applied Physics School of ScienceNanjing University of Posts and TelecommunicationsNanjing 210003China

Classification of quantum phases is one of the most important areas of research in condensed matter *** this work,we obtain the phase diagram of one-dimensional quasiperiodic models via unsupervised ***,we choose two advanced unsupervised learning algorithms,namely,density-based spatial clustering of applications with noise(DBSCAN)and ordering points to identify the clustering structure(OPTICS),to explore the distinct phases of the Aubry–André–Harper model and the quasiperiodic p-wave *** unsupervised learning results match well with those obtained through traditional numerical ***,we assess similarity across different algorithms and find that the highest degree of similarity between the results of unsupervised learning algorithms and those of traditional algorithms exceeds 98%.Our work sheds light on applications of unsupervised learning for phase classification.

关键词： quantum phase quasiperiodic machine learning

Nickel-copper alloying arrays realizing efficient co-electrosynthesis of adipic acid and hydrogen

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Journal of Energy Chemistry 2025年第02期101卷 7-15页

作者： Xuhui Ren Qianyu Zhang Yun tong Guorong zhou Cong Lin Yanying Zhao Pengzuo Chen School of Chemistry and Chemical Engineering Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province Zhejiang Sci-Tech University

Constructing electrocatalytic overall reaction technology to couple the electrosynthesis of adipic acid with energy-saving hydrogen production is of significant for sustainable energy ***,the development of highly-active bifunctional electrocatalysts remains a ***,3D hierarchical nickel-copper alloying arrays with dendritic morphology are manufactured by a simple electrodeposition process,standing for the excellent bifunctional electrocatalyst towards the co-production of adipic acid and H2from cyclohexanone and *** membrane-free flow electrolyzer of Cu0.81Ni0.19/NF shows the superior electrooxidation performance of ketone-alcohol（KA） oil with high faradaic efficiencies of over 90% for adipic acid and H2,robust stability over 200 h as well as a high yield of 0.6 mmol h-1for adipic acid at 100 mA ***-situ spectroscopy indicates the Cu0.81Ni0.19alloy contributes to forming more active NiOOH species to involve in the conversion of cyclohexanone to adipic acid,while the proposed reaction pathway undergoes the 2-hydroxycyclohexanone and 2,7-oxepanedione ***,the theoretical calculations confirm that the optimal electronic interaction,boosted reaction kinetics as well as improved adsorption free energy of reaction intermediates,synergistically endows Cu0.81Ni0.19alloy with superior bifunctional performance.

关键词： Adipic acid Cu0.81Ni0.19 alloy Cyclohexanone oxidation reaction Hydrogen evolution reaction Hydrogen fuel

Interfacial Zn^(2+)-solvation regulator towards reversible and stable Zn anode

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Journal of Energy Chemistry 2025年第1期100卷 684-692页

作者： Miao zhou Xiongbin Luo Hang Li Shan Guo Zhuang tong Xiaotao zhou Xu Li Zhaohui Hou Shuquan Liang Guozhao Fang College of Mechanical Engineering Key Laboratory of Hunan Province for Advanced Carbon-based Functional MaterialsHunan Institute of Science and TechnologyYueyang 414006HunanChina School of Materials Science and Engineering Key Laboratory of Electronic Packaging and Advanced Functional Materials of Hunan ProvinceCentral South UniversityChangsha 410083HunanChina College of Materials and Metallurgy Guizhou UniversityGuiyang 550000GuizhouChina National Energy Metal Resources and New Materials Key Laboratory Central South UniversityChangsha 410083HunanChina

Aqueous zinc-ion batteries (AZIBs) are fundamentally challenged by the instability of the electrode/electrolyte interface,predominantly due to irreversible zinc (Zn) deposition and hydrogen ***,the intricate mechanisms behind the electrochemical discrepancies induced by interfacial Zn^(2+)-solvation and deposition behavior demand comprehensive *** molecules endowed with special functional groups (such as hydroxyl,carboxyl,etc.) have the potential to significantly optimize the solvation structure of Zn^(2+)and regulate the interfacial electric double layer (EDL).By increasing nucleation overpotential and decreasing interfacial free energy,these functional groups facilitate a lower critical nucleation radius,thereby forming an asymptotic nucleation model to promote uniform Zn ***,this study presents a pioneering approach by introducing trace amounts of n-butanol as solvation regulators to engineer the homogenized Zn (H-Zn) anode with a uniform and dense *** interfacial reaction and structure evolution are explored by in/ex-situ experimental techniques,indicating that the H-Zn anode exhibits dendrite-free growth,no by-products,and weak hydrogen evolution,in sharp contrast to the bare ***,the H-Zn anode achieves a remarkable Zn utilization rate of approximately 20% and simultaneously sustains a prolonged cycle life exceeding 500 ***,the H-Zn//NH_(4)V_(4)O^(10)(NVO) full battery showcases exceptional cycle stability,retaining 95.04%capacity retention after 400 cycles at a large current density of 5 A g^(-1).This study enlightens solvation-regulated additives to develop Zn anode with superior utilization efficiency and extended operational lifespan.

关键词： Aqueous zinc-ion batteries Zn^(2+)-solvation structure Interfacial reaction Asymptotic nucleation model Reversible and stable Zn anode

Study on the hydrogen absorption properties of a YGdTbDyHo rare-earth high-entropy alloy

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 127-135页

作者： tongyue Li Ziliang Xie Wenjiao zhou Huan tong Dawen Yang Anjia Zhang Yuan Wu Xiping Song State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China Whole Win(Beijing)Materials Sci.&Tech.Co. Ltd.Beijing 100083China

This study investigated the microstructure and hydrogen absorption properties of a rare-earth high-entropy alloy(HEA),*** indicated that the YGdTbDyHo alloy had a microstructure of equiaxed grains,with the alloy elements distributed *** hydrogen absorption,the phase structure of the HEA changed from a solid solution with an hexagonal-close-packed(HCP)structure to a high-entropy hydride with an faced-centered-cubic(FCC)structure without any secondary phase *** alloy demonstrated a maximum hydrogen storage capacity of 2.33 H/M(hydrogen atom/metal atom)at 723 K,with an enthalpy change(ΔH)of-141.09 kJ·mol^(-1)and an entropy change(ΔS)of-119.14 J·mol^(-1)·K^(-1).The kinetic mechanism of hydrogen absorption was hydride nucleation and growth,with an apparent activation energy(E_(a))of 20.90 kJ·mol^(-1).Without any activation,the YGdTbDyHo alloy could absorb hydrogen quickly(180 s at 923 K)with nearly no incubation period *** reason for the obtained value of 2.33 H/M was that the hydrogen atoms occupied both tetrahedral and octahedral *** results demonstrate the potential application of HEAs as a high-capacity hydrogen storage material with a large H/M ratio,which can be used in the deuterium storage field.

关键词： rare-earth high-entropy alloy hydrogen absorption capacity pressure–composition–temperature curves kinetics

PriChain: Efficient Privacy-Preserving Fine-Grained Redactable Blockchains in Decentralized Settings

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Chinese Journal of Electronics 2025年第1期34卷 82-97页

作者： Hongchen Guo Weilin Gan Mingyang Zhao chuan Zhang tong Wu Liehuang Zhu Jingfeng Xue School of Computer Science and Technology Beijing Institute of Technology School of Cyberspace Science and Technology Beijing Institute of Technology School of Computer and Communication Engineering University of Science and Technology Beijing

Recently, redactable blockchain has been proposed and leveraged in a wide range of real systems for its unique properties of decentralization, traceability, and transparency while ensuring controllable on-chain data redaction. However, the development of redactable blockchain is now obstructed by three limitations, which are data privacy breaches, high communication overhead, and low searching efficiency, respectively. In this paper, we propose PriChain, the first efficient privacy-preserving fine-grained redactable blockchain in decentralized settings. PriChain provides data owners with rights to control who can read and redact on-chain data while maintaining downward compatibility, ensuring the one who can redact will be able to read. Specifically, inspired by the concept of multi-authority attribute-based encryption, we utilize the isomorphism of the access control tree, realizing fine-grained redaction mechanism, downward compatibility, and collusion resistance. With the newly designed structure, PriChain can realize O（n） communication and storage overhead compared to prior O（n2） schemes. Furthermore, we integrate multiple access trees into a tree-based dictionary, optimizing searching efficiency. Theoretical analysis proves that PriChain is secure against the chosen-plaintext attack and has competitive complexity. The experimental evaluations show that PriChain realizes 10× efficiency improvement of searching and 100× lower communication and storage overhead on average compared with existing schemes.

关键词： Resistance Access control Data privacy Dictionaries Blockchains Encryption Complexity theory Usability Protection