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Controlling underestimation bias in reinforcement learning via minmax operation

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Chinese Journal of Aeronautics 2024年第7期37卷 406-417页

作者： Fanghui HUANG Yixin HE Yu ZHANG xinyang DENG wen JIANG School of Electronics and Information Northwestern Polytechnical UniversityXi’an 710129China College of Information Science and Engineering Jiaxing UniversityJiaxing 314001China

Obtaining the accurate value estimation and reducing the estimation bias are the key issues in reinforcement ***,current methods that address the overestimation problem tend to introduce underestimation,which face a challenge of precise decision-making in many *** address this issue,we conduct a theoretical analysis of the underestimation bias and propose the minmax operation,which allow for flexible control of the estimation ***,we select the maximum value of each action from multiple parallel state-action networks to create a new state-action value ***,a minimum value is selected to obtain more accurate value ***,based on the minmax operation,we propose two novel algorithms by combining Deep Q-Network(DQN)and Double DQN(DDQN),named minmax-DQN and ***,we conduct theoretical analyses of the estimation bias and variance caused by our proposed minmax operation,which show that this operation significantly improves both underestimation and overestimation biases and leads to the unbiased ***,the variance is also reduced,which is helpful to improve the network training ***,we conduct numerous comparative experiments in various environments,which empirically demonstrate the superiority of our method.

关键词： Reinforcement learning Minmax operation Estimation bias Underestimation bias Variance

Air target intention recognition and causal effect analysis combining uncertainty information reasoning and potential outcome framework

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Chinese Journal of Aeronautics 2024年第1期37卷 287-299页

作者： Yu ZHANG Fanghui HUANG xinyang DENG Mingda LI wen JIANG School of Electronics and Information Northwestern Polytechnical UniversityXi’an 710129China

Recognizing target intent is crucial for making decisions on the ***,the imperfect and ambiguous character of battlefield situations challenges the validity and causation analysis of classical intent recognition *** with the challenge,a target intention causal analysis paradigm is proposed by combining with an Intervention Retrieval(IR)model and a Hybrid Intention Recognition(HIR)*** target data acquired by the sensors are modelled as Basic Probability Assignments(BPAs)based on evidence theory to create uncertain ***,the HIR model is utilized to recognize intent for a tested sample from uncertain ***,the intervention operator under the evidence structure is utilized to perform attribute intervention on the tested *** retrieval is performed in the sample database based on the IR model to generate the intention distribution of the pseudo-intervention samples to analyze the causal effects of individual sample *** simulation results demonstrate that our framework successfully identifies the target intention under the evidence structure and goes further to analyze the causal impact of sample attributes on the target intention.

关键词： Causal effect analysis Hybrid intention recognition Intervention retrieval Target intention Uncertainty reasoning

Tuning the surface electronic structure of noble metal aerogels to promote the electrocatalytic oxygen reduction

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Journal of Energy Chemistry 2024年第2期89卷 557-564,I0013页

作者： Hongxing Yuan Wei Gao xinhao Wan Jianqi Ye Dan wen State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072ShaanxiChina

The sluggish kinetics of the oxygen reduction reaction(ORR)is the bottleneck for various electrochemical energy conversion *** the electronic structure of electrocatalysts by ligands has received particular attention in deriving valid ORR ***,the surface electronic structure of Ptbased noble metal aerogels(NMAs)was modulated by various organic ligands,among which the electron-withdrawing ligand of 4-methylphenylene effectively boosted the ORR *** calculations suggested the smaller energy barrier for the transformation of O^(*) to OH^(*) and downshift the d-band center of Pt due to the interaction between 4-methylphenylene and the surface metals,thus enhancing the ORR intrinsic *** Pt3Ni and Pt Pd aerogels with 4-methylphenylene decoration performed significant enhancement in ORR activity and durability in different ***,the 4-methylphenylene modified Pt Pd aerogel exhibited the higher halfwave potential of 0.952 V and the mass activity of 10.2 times of commercial Pt/*** work explained the effect of electronic structure on ORR electrocatalytic properties and would promote functionalized NMAs as efficient ORR electrocatalysts.

关键词： Noble metal aerogels Surface electronic structure ORR Electrocatalyst Organic ligands

Fabrication and integration of photonic devices for phase-change memory and neuromorphic computing

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International Journal of Extreme Manufacturing 2024年第2期6卷 2-27页

作者： wen Zhou Xueyang Shen xiaolong Yang Jiangjing Wang Wei Zhang Center for Alloy Innovation and Design(CAID) State Key Laboratory for Mechanical Behavior of MaterialsXi’an Jiaotong UniversityXi’an 710049People’s Republic of China

In the past decade,there has been tremendous progress in integrating chalcogenide phase-change materials(PCMs)on the silicon photonic platform for non-volatile memory to neuromorphic in-memory computing *** particular,these non von Neumann computational elements and systems benefit from mass manufacturing of silicon photonic integrated circuits(PICs)on 8-inch wafers using a 130 nm complementary metal-oxide semiconductor *** manufacturing based on deep-ultraviolet lithography and electron-beam lithography enables rapid prototyping of PICs,which can be integrated with high-quality PCMs based on the wafer-scale sputtering technique as a back-end-of-line *** this article,we present an overview of recent advances in waveguide integrated PCM memory cells,functional devices,and neuromorphic systems,with an emphasis on fabrication and integration processes to attain state-of-the-art device *** a short overview of PCM based photonic devices,we discuss the materials properties of the functional layer as well as the progress on the light guiding layer,namely,the silicon and germanium waveguide ***,we discuss the cleanroom fabrication flow of waveguide devices integrated with thin films and nanowires,silicon waveguides and plasmonic microheaters for the electrothermal switching of PCMs and mixed-mode ***,the fabrication of photonic and photonic–electronic neuromorphic computing systems is *** systems consist of arrays of PCM memory elements for associative learning,matrix-vector multiplication,and pattern *** large-scale integration,the neuromorphic photonic computing paradigm holds the promise to outperform digital electronic accelerators by taking the advantages of ultra-high bandwidth,high speed,and energy-efficient operation in running machine learning algorithms.

关键词： nanofabrication silicon photonics phase-change materials non-volatile photonic memory neuromorphic photonic computing

Multifaceted roles of lymphatic and blood endothelial cells in the tumor microenvironment of hepatocellular carcinoma:A comprehensive review

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World Journal of Hepatology 2024年第4期16卷 537-549页

作者： Jing-Jing Li Jia-xi Mao Han-xiang Zhong Yuan-Yu Zhao Fei Teng xin-Yi Lu Li-Ye Zhu Yang Gao Hong Fu wen-Yuan Guo Department of Liver Surgery and Organ Transplantation Shanghai Changzheng HospitalNaval Medical UniversityShanghai 200003China

The tumor microenvironment is a complex network of cells,extracellular matrix,and signaling molecules that plays a critical role in tumor progression and *** and blood vessels are major routes for solid tumor metastasis and essential parts of tumor drainage ***,recent studies have shown that lymphatic endothelial cells(LECs)and blood endothelial cells(BECs)also play multifaceted roles in the tumor microenvironment beyond their structural functions,particularly in hepatocellular carcinoma(HCC).This comprehensive review summarizes the diverse roles played by LECs and BECs in HCC,including their involvement in angiogenesis,immune modulation,lymphangiogenesis,and *** providing a detailed account of the complex interplay between LECs,BECs,and tumor cells,this review aims to shed light on future research directions regarding the immune regulatory function of LECs and potential therapeutic targets for HCC.

关键词： Lymphatic endothelial cells Blood endothelial cells Hepatocellular carcinoma Tumor microenvironment

线粒体未折叠蛋白反应在棕榈酸诱导肾小管上皮细胞脂质聚集中的作用

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西安交通大学学报（医学版） 2024年第3期45卷 419-427页

作者：温睿智杜晓刚重庆医科大学附属第一医院肾内科重庆400042

目的探讨线粒体未折叠蛋白反应(mitochondrial unfolded protein reaction,UPR^(mt))对肾小管上皮细胞(human kidney 2,HK-2)脂代谢的影响。方法采用棕榈酸(palmitic acid,PA)诱导HK-2细胞内脂质聚集,分别予siRNA抑制UPR^(mt)或巴多索隆(the 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid,CDDO)增强UPR^(mt)。油红染色观察细胞内脂质聚集情况,线粒体膜电位检测试剂盒(JC-1)测定线粒体膜电位(mitochondrial membrane potential,MMP),Mito-SOX测定线粒体内活性氧(reactive oxygen species,ROS)含量,Western blotting检测HSP60、LONP1、CLPP、ACOX1、PPARα、PGC1α、CPT1α蛋白表达。结果PA诱导HK-2细胞脂质聚集、MMP降低、ROS产生增多及UPR^(mt)关键蛋白HSP60、LONP1表达降低;抑制UPR^(mt)可加剧PA导致的脂质聚集、MMP降低、ROS产生增多,HSP60、LONP1表达进一步降低;增强UPR^(mt)可缓解PA导致的脂质聚集、MMP降低、ROS产生增多以及HSP60、LONP1表达降低。结论PA诱导的HK-2细胞脂质聚集可能与线粒体功能障碍有关,UPR^(mt)在该过程中对HK-2细胞具有保护作用。

关键词：线粒体未折叠蛋白反应(UPR^(mt)) 棕榈酸(PA) 肾小管上皮细胞(HK-2) 脂质聚集活性氧(ROS)

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Robust fixed-time flight controller for a dual-system convertible UAV in the cruise mode

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Defence Technology（防务技术） 2024年第9期39卷 53-66页

作者： Lulu Chen Zhenbao Liu Qingqing Dang wen Zhao wenyu Chen School of Civil Aviation Northwestern Polytechnical UniversityXi'an 710072China Shenzhen Research Institute of Northwestern Polytechnical University Shenzhen 518057China Air and Missile Defense College Air Force Engineering UniversityXi'an 710051China

This paper investigates the attitude tracking control problem for the cruise mode of a dual-system convertible unmanned aerial vehicle(UAV)in the presence of parameter uncertainties,unmodeled uncertainties and wind ***,a fixed-time disturbance observer(FXDO)based on the bi-limit homogeneity theory is designed to estimate the lumped disturbance of the convertible UAV ***,a fixed-time integral sliding mode control(FxiSMC)is combined with the FXDO to achieve strong robustness and chattering ***-limit homogeneity theory and Lyapunov theory are applied to provide detailed proof of the fixed-time ***,numerical simulation experimental results verify the robustness of the proposed algorithm to model parameter uncertainties and wind *** addition,the proposed algorithm is deployed in a open-source UAV autopilot and its effectiveness is further demonstrated by hardware-in-the-loop experimental results.

关键词： Convertible UAV Flight control Disturbance observer Fixed-time control

Preparation of a high-performance synthetic pitch from aromatic hydrocarbons containing N/Cl

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新型炭材料（中英文） 2024年第4期39卷 655-667页

作者： ZHANG Yu-kun LIN xiong-chao GAO Hong-feng xi wen-shuai WANG Cai-hong WANG Yong-gang School of Chemical&Environmental Engineering China University of Mining and Technology(Beijing)Beijing 100083China

The preparation of a synthetic pitch from aromatic monomers could easily regulate structure orientation at the molecu-lar level,which would be useful in *** isotropic synthetic pitch was prepared by a chlorine-and/or nitrogen-induced sub-stitution polymerization reaction method using aromatic hydrocarbon precursors containing Cl and N,which for this study were chloromethyl naphthalene and *** method was verified by investigating the structural changes under different synthesis conditions,and the synthesis mechanism induced by aromatics containing Cl was also *** result shows that the pyridinic N in quinoline contains a lone pair of electrons,and is an effective active site to induce the polymerization reaction by coupling with aromatic hydrocarbons containing *** reaction between such free radicals causes strong homopolymerization and oligomeriza-tion.A higher reaction temperature and longer reaction time significantly increased the degree of polymerization and thus increased the softening point of the pitch.A linear molecular structure was formed by the Cl substitution reaction,which produced a highly spinnable pitch with a softening point of 258.6℃,and carbon fibers with a tensile strength of 1163.82 MPa were *** study provides a relatively simple and safe method for the preparation of high-quality spinnable pitch.

关键词： Quinoline 1-Chloromethyl-naphthalene Synthetic pitch Spinnability Carbon fiber

Biological sources, paleoenvironment, and organic matter enrichment in source rocks of the Ordovician Majiagou Formation, Ordos Basin, China:Evidence from biomarkers,microfossils, and inorganic geochemical analyses

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Journal of Palaeogeography 2024年第1期13卷 92-115页

作者： Jing-Jing Cao wen-Zhe Gang Shang-Ru Yang State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Bejing)Beijing 102249China College of Geosciences China University of Petroleum(Bejing)Beijing 102249China Oil and Gas Technology Research Institute PetroChina Changqing Oifield CompanyXi'an 710018Shaanxi ProvinceChina

Carbonate deposits in the Ordovivian Majiagou Formation are significant source rocks for natural gas generation in the Ordos Basin, northwestern China. Previous studies mainly focused on the organic matter enrichment mechanism of shales rather than carbonate rocks. The biological sources and paleoenvironment of carbonate source rocks, and the main controlling factors of organic matter enrichment in the carbonate source rocks were studied in this paper in combination with evidence from biomarkers, microfossils and inorganic geochemistry analysis. The results show that four types of microfacies were identified in the Majiagou Formation, respectively as: mud flat microfacies, mud-dolomite flat microfacies, dolomite flat microfacies, and open marine microfacies. The biological sources of organic matter are chiefly planktonic algae, followed by bacteria. The mud flat and mud-dolomite flat contain a high abundance of terrigenous detrital inputs, as indicated by the high content of Al_(2)O_(3), TiO_(2), Th, and Zr. The low Sr/Cu and high Rb/Sr values reveal warm and humid paleoclimate conditions in the mud flat and mud-dolomite flat, whereas the dolomite flat and open marine were likely formed in hot and arid paleoclimate conditions. The mud flat and mud-dolomite flat deposits were characterized by high paleoproductivity of the Majiagou Formation. Low Sr/Ba values were found in the mud flat samples, indicating fresh to brackish water condition, whereas samples of other facies have a relatively high degree of salinity. Based on U_(auth), Mo_(auth), Cr_(auth), Co_(auth), δCe, and δEu values, the mud flat microfacies was formed in a suboxic and anoxic environment, whereas the mud-dolomite flat, dolomite flat and open marine microfacies were within dysoxic to oxic conditions. A model of organic matter enrichment in the Majiagou Formation is thus established. The level of terrigenous detrital inputs is the principal factor of organic matter enrichment in the Majiagou Formation,

关键词： Biological source Microfacies Trace elements Organic matter Majiagou Formation Ordos Basin