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Attitude-adjusting dynamical behavior of cubic rover on low-gravity testbed

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Astrodynamics 2024年第1期8卷 149-159页

作者： Bowen jiang Muhammad Talha Hussain Xiangyuan Zeng School of Automation Beijing Institute of TechnologyBeijing100081China

Cubic rovers that traverse by hopping systems are promising in low-gravity *** several analyses of the control methods and mobility of the cubic rover are available,investigations of its attitude-adjusting behavior are still *** study derives the dynamic equations of the two attitude-adjusting modes of the cubic rover,referred to as walking and *** relationships between the speed threshold and rotation angle of the cubic rover were investigated in both rigid and regolith environments using a self-designed low-gravity *** studies were conducted by considering the experimental and simulated *** results of this study can be interesting for roving mission planning when exploring planetary moons and small celestial bodies.

关键词： low-gravitytestbed attitude-adjusting motion cubic rover experimental study

Control of electromechanical performance in 3D printing latticestructured BaTiO_(3) piezoelectric ceramics

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Journal of Advanced Ceramics 2024年第7期13卷 987-1001页

作者： Zhujun jiang Yinghong Sun Jimin Chen Yong Zeng Faculty of Materials and Manufacturing Beijing University of TechnologyBeijing 100124China Beijing Engineering Research Center of 3D Printing for Digital Medical Health Beijing University of TechnologyBeijing 100124China

Barium titanate(BaTiO_(3))piezoelectric ceramics with triply periodic minimal surface(TPMS)structures have been frequently used in filters,engines,artificial bones,and other fields due to their high specific surface area,high thermal stability,and good heat ***,only a limited number of studies have analyzed the effect of various parameters,such as different wall thicknesses and porosities of TPMS structures,on ceramic electromechanical *** this study,we first employed vat photopolymerization(VPP)three-dimensional(3D)printing technology to fabricate high-performance BaTiO_(3) *** investigated the slurry composition design and forming process and designed a stepwise sintering postprocessing technique to achieve a density of 96.3%and a compressive strength of 250±25 MPa,with the piezoelectric coefficient(d33)reaching 263 pC/***,we explored the influence of three TPMS structures,namely,diamond,gyroid,and Schwarz P,on the piezoelectric and mechanical properties of BaTiO_(3) ceramics,with the gyroid structure identified as exhibiting optimal ***,we examined the piezoelectric and mechanical properties of BaTiO_(3) ceramics with the gyroid structure of varying wall thicknesses and porosities,thus enabling the modulation of ceramic electromechanical performance.

关键词： three-dimensional(3D)printing piezoelectric ceramics porous structure mechanical properties electrical properties

Unraveling the Cenozoic carbon cycle by reconstructing carbonate compensation depth(CCD)

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Science China Earth Sciences 2024年第6期67卷 1743-1758页

作者： Kaixun XIAO Xiumian HU Jingxin jiang Jiahao WANG State Key Laboratory of Mineral Deposit Research School of Earth Sciences and EngineeringNanjing UniversityNanjing 210023China

The Carbonate Compensation Depth(CCD)refers to the depth within the ocean where the production and dissolution rates of carbonates reach equilibrium,widely likened to the oceanic calcareous‘snowline’.The reconstruction of deep-time CCD has significant implications for understanding ocean circulation,seawater chemical conditions,sediment distribution,and the surface carbon *** paper critically reviews the methods for CCD reconstruction,summarizes the driving mechanisms of the Cenozoic CCD evolution and its association with the carbon cycle,and offers insights into future directions for CCD *** reconstruction has evolved over the past half century from early qualitative to quantitative *** methodological improvements have markedly improved the accuracy and resolution of *** studies have indicated a general trend of the CCD deepening across major ocean basins since the Cenozoic,interspersed with a minor shallowing phase during the *** variations in the CCD are primarily influenced by factors such as ocean productivity,weathering,and shelf-basin *** climate events such as the Paleocene-Eocene Thermal Maximum,the CCD exhibits pulselike *** research should focus on precision and quantification while integrating model simulations to further explore the correlations and response mechanisms between the CCD and the paleoclimate as well as the carbon cycle.

关键词： Carbonate Compensation Depth Cenozoic Carbon cycle Paleoclimate Paleoceanography

Federated Meta Reinforcement Learning for Personalized Tasks

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Tsinghua Science and Technology 2024年第3期29卷 911-926页

作者： Wentao Liu Xiaolong Xu Jintao Wu Jielin jiang School of Computer Science Nanjing University of Information Science and TechnologyNanjing 210044China School of Software Nanjing University of Information Science and TechnologyNanjing 210044China

As an emerging privacy-preservation machine learning framework,Federated Learning(FL)facilitates different clients to train a shared model collaboratively through exchanging and aggregating model parameters while raw data are kept local and *** this learning framework is applied to Deep Reinforcement Learning(DRL),the resultant Federated Reinforcement Learning(FRL)can circumvent the heavy data sampling required in conventional DRL and benefit from diversified training data,besides privacy preservation offered by *** FRL implementations presuppose that clients have compatible tasks which a single global model can *** practice,however,clients usually have incompatible(different but still similar)personalized tasks,which we called task *** may severely hinder the implementation of FRL for practical *** this paper,we propose a Federated Meta Reinforcement Learning(FMRL)framework by integrating Model-Agnostic Meta-Learning(MAML)and ***,we innovatively utilize Proximal Policy Optimization(PPO)to fulfil multi-step local training with a single round of ***,considering the sensitivity of learning rate selection in FRL,we reconstruct the aggregation optimizer with the Federated version of Adam(Fed-Adam)on the server *** experiments demonstrate that,in different environments,FMRL outperforms other FL methods with high training efficiency brought by Fed-Adam.

关键词： federated learning reinforcement learning meta-learning personalization

STDNet: A Spatio-Temporal Decomposition Neural Network for Multivariate Time Series Forecasting

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Tsinghua Science and Technology 2024年第4期29卷 1232-1247页

作者： Zhuolun jiang Zefei Ning Hao Miao Li Wang College of Computer Science and Technology(College of Data Science) Taiyuan University of TechnologyJinzhong 030600China

Long-term multivariate time series forecasting is an important task in engineering applications. It helps grasp the future development trend of data in real-time, which is of great significance for a wide variety of fields. Due to the non-linear and unstable characteristics of multivariate time series, the existing methods encounter difficulties in analyzing complex high-dimensional data and capturing latent relationships between multivariates in time series, thus affecting the performance of long-term prediction. In this paper, we propose a novel time series forecasting model based on multilayer perceptron that combines spatio-temporal decomposition and doubly residual stacking, namely Spatio-Temporal Decomposition Neural Network (STDNet). We decompose the originally complex and unstable time series into two parts, temporal term and spatial term. We design temporal module based on auto-correlation mechanism to discover temporal dependencies at the sub-series level, and spatial module based on convolutional neural network and self-attention mechanism to integrate multivariate information from two dimensions, global and local, respectively. Then we integrate the results obtained from the different modules to get the final forecast. Extensive experiments on four real-world datasets show that STDNet significantly outperforms other state-of-the-art methods, which provides an effective solution for long-term time series forecasting.

关键词： time series forecasting multivariate time series spatio-temporal decomposition

Robust boundary-induced bulk propagations in elastic waveguides with nonplanar surfaces

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Science China(Physics,Mechanics & Astronomy) 2024年第4期67卷 88-96页

作者： Baizhan Xia Jielong Zhang Zihan jiang Jianting Liu State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China

Trivial elastic waveguides induced by line defects and nontrivial elastic waveguides protected by topological edge states have been extensively examined in planar waveguide *** these investigations,little is known about topologically protected bulk states and their resulting robust transmission properties,especially in nonplanar elastic waveguides with folded,curved,and twisted *** Dirac waveguides with robust boundary-induced bulk states are *** states arise from the truncated boundaries of bulks with linear Dirac conical dispersions,differing from topologically protected edge states ensured by the bulk-edge *** proof is provided,in which boundary-induced bulk states show robustly high-throughput transmissions along the waveguides,even with folded,curved,and twisted *** results not only open up new avenues for examining novel topological phenomena about bulk but also offer new platforms for developing topological devices with nonplanar surfaces.

关键词： elastic waveguides boundary-induced bulk propagations Dirac conical dispersions nonplanar surfaces

Effect of miR-124 Overexpression under Wnt/β-catenin Signaling Pathway on Inflammatory Factor and Epidermal Growth Factor in Rats with Precancerous Gastric Lesions

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Chinese Journal of Biomedical Engineering 2024年第01期33卷 17-26页

作者： ZHOU Li-jiang Zhejiang Chinese Medical University Shangyu People's Hospital of Shaoxing

Objective: To investigate the effects of miR-124 overexpression on inflammatory factors and epidermal growth factor in rats with gastric precancerous lesions by modulating the Wnt/β-catenin signaling pathway. Methods: Eighty SPF-grade Wistar rats were selected as the research subjects. After adaptive feeding,they were divided into 4 groups using a random number table method. The control group was fed a regular diet, while the model group, low expression group, and overexpression group of rats were treated with N-methyl-N'-nitro-N-nitrosoguanidine to establish a model of gastric cancer precancerous lesions. After successful modeling, the control group and model group rats were injected intraperitoneally with 0.9% sodium chloride solution, the low-expression group rats were injected intraperitoneally with miR-124-5p inhibitor, and the over-expression group rats were injected intraperitoneally with miR-124-5p mimic. After 8 weeks of continuous injection, the levels of miR-124,Wnt/β-catenin signaling pathway-related proteins, inflammatory factors, and epidermal growth factor were observed and compared among the four groups of rats. Results: The differences in the relative expression of miR-124 among the four groups of rats were statistically significant(P<0.05); the differences in the expression of Wnt protein andβ-catenin protein among the four groups of rats were statistically significant(P<0.05),and the expression of Wnt protein and β-catenin protein in the overexpression group was significantly higher than that of the control group, and significantly lower than that in the model group and the low-expression group; the levels of IL-1β, IL-6, and TNF-αof rats in the four groups of rats IL-1β, IL-6 and TNF-α levels were statistically different(P<0.05), and the levels of IL-1β, IL-6 and TNF-α in rats in the overexpression group were higher than those in the model group and significantly lower than those in the model group and the low-expression group(P<0.05); the differ

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Blockchain-based immunization against kleptographic attacks

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Science China(Information Sciences) 2024年第7期67卷 172-183页

作者： Changsong jiang Chunxiang XU Jie CHEN Kefei CHEN School of Computer Science and Engineering University of Electronic Science and Technology of China Yangtze Delta Region Institute (Huzhou) University of Electronic Science and Technology of China Department of Mathematics Hangzhou Normal University

Adversarial implementations of cryptographic primitives called kleptographic attacks cause the leakage of secret information. Subliminal channel attacks are one of the kleptographic attacks. In such attacks, backdoors are embedded in implementations of randomized algorithms to elaborately control randomness generation, such that the secrets will be leaked from biased outputs. To thwart subliminal channel attacks, double-splitting is a feasible solution, which splits the randomness generator of a randomized algorithm into two independent generators. In this paper, we instantiate double-splitting to propose a secure randomness generation algorithm dubbed SRG using two physically independent generators: ordinary and public randomness generators. Based on public blockchains, we construct the public randomness generator,which can be verified publicly. Hashes of a sufficient number of consecutive blocks that are newly confirmed on a blockchain are used to produce public randomness. In SRG, outputs from the two generators are taken as inputs of an immunization function. SRG accomplishes immunization against subliminal channel ***, we discuss the application strategies of SRG for symmetric and public-key encryption.

关键词： kleptographic attacks subliminal channel blockchain immunization randomized algorithm

New black-to-white hole solutions with improved geometry and energy conditions

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 30-43页

作者： Zhongwen Feng Yi Ling Xiaoning Wu Qingquan jiang School of Physics and Astronomy China West Normal UniversityNanchong 637009China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China School of Physics University of Chinese Academy of SciencesBeijing 100049China Institute of Mathematics Academy of Mathematics and System Science and Hua Loo-Keng Key Laboratory of MathematicsChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100190China

We construct new black-to-white hole solutions which connect the geometry of spacetime at some gluing surface inside the *** continuity of the metric can be guaranteed up to the arbitrary order which is controlled by the power factor *** sort of black-to-white holes is characterized by the sub-Planckian scalar curvature,independent of the mass of black-to-white *** importantly,we show that the energy condition is only violated within a small region near the gluing *** geodesics of particles within the region from black hole to white hole is also *** turns out that the matter falling into the black hole may pass through the center without singularity and come out from the white *** scenario provides novel ideas for understanding the information loss paradox in traditional black hole physics.

关键词： regular black hole energy condition singularity quantum gravity