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A credible traffic prediction method based on self-supervised causal discovery

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science China(Information sciences) 2024年第5期67卷 244-258页

作者： Dan WANG Yingjie liu bin sONG state Key Laboratory of Integrated services Networks Xidian University

Next-generation wireless network aims to support low-latency, high-speed data transmission services by incorporating artificial intelligence(AI) technologies. To fulfill this promise, AI-based network traffic prediction is essential for pre-allocating resources, such as bandwidth and computing power. This can help reduce network congestion and improve the quality of service(Qos) for users. Most studies achieve future traffic prediction by exploiting deep learning and reinforcement learning, to mine spatio-temporal correlated variables. Nevertheless, the prediction results obtained only by the spatio-temporal correlated variables cannot reflect real traffic changes. This phenomenon prevents the true prediction variables from being inferred, making the prediction algorithm perform poorly. Inspired by causal science, we propose a novel network traffic prediction method based on self-supervised spatio-temporal causal discovery(ssTCD). We first introduce the Granger causal discovery algorithm to build a causal graph among prediction variables and obtain spatio-temporal causality in the observed data, which reflects the real reasons affecting traffic ***, a graph neural network(GNN) is adopted to incorporate causality for traffic prediction. Furthermore,we propose a self-supervised method to implement causal discovery to to address the challenge of lacking ground-truth causal graphs in the observed data. Experimental results demonstrate the effectiveness of the ssTCD method.

关键词： wireless network traffic prediction causal discovery self-supervised

Tuning mechanical behaviors of highly entangled hydrogels with the random distribution of mobile entanglements

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 277-294页

作者： Jinlong liu Di LU bin CHEN Department of Engineering Mechanics Zhejiang UniversityHangzhou 310027China Beijing system Design Institute of Electro-Mechanic Engineering Beijing 100854China Intelligent Robotic Research Center Zhejiang LaboratoryHangzhou 310027China Key Laboratory of soft Machines and smart Devices of Zhejiang Province Hangzhou 311100China

Highly entangled hydrogels exhibit excellent mechanical properties,including high toughness,high stretchability,and low *** considering the evolution of randomly distributed entanglements within the polymer network upon mechanical stretches,we develop a constitutive theory to describe the large stretch behaviors of these *** the theory,we utilize a representative volume element(RVE)in the shape of a cube,within which there exists an averaged chain segment along each edge and a mobile entanglement at each *** employing an explicit method,we decouple the elasticity of the hydrogels from the sliding motion of their entanglements,and derive the stress-stretch relations for these *** present theoretical analysis is in agreement with experiment,and highlights the significant influence of the entanglement distribution within the hydrogels on their *** also implement the present developed constitutive theory into a commercial finite element software,and the subsequent simulations demonstrate that the exact distribution of entanglements strongly affects the mechanical behaviors of the structures of these ***,the present theory provides valuable insights into the deformation mechanism of highly entangled hydrogels,and can aid in the design of these hydrogels with enhanced performance.

关键词： highly entangled hydrogel constitutive theory entanglement gamma distribution

simultaneous measurement of distance and speed using frequency-modulated continuous-wave self-mixing interferometry and all-phase fast Fourier transform

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Chinese Optics Letters 2024年第7期22卷 29-34页

作者： Jinyuan Yuan bin liu school of Physics and Optoelectronics Xiangtan UniversityXiangtan 411105China sECTE University of WollongongWollongong NSW 2522Australia

In this work,we propose a method using frequency-modulated continuous-wave(FMCW)self-mixing interferometry(sMI)and all-phase fast Fourier transform(APFFT)for simultaneous measurement of speed and *** offers superior accuracy in frequency determination by mitigating issues like the fence effect and spectrum leakage,contributing to the high-accuracy measurement for speed and *** simulations and experiments have demonstrated relative errors at the levels of 10^(−4) and 10^(−3. for distance and speed measurements,***,factors impacting measurement performance have been *** proposed method provides a high-performance and cost-effective solution for distance and speed measurements,applicable across scientific research and various industrial domains.

关键词： self-mixing interferometry frequency-modulated continuous-wave interferometry all-phase fast Fourier transform measurement of distance and speed.

Mg-doped,carbon-coated,and prelithiated siO_(x) as anode materials with improved initial Coulombic efficiency for lithium-ion batteries

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Carbon Energy 2024年第3期6卷 204-214页

作者： bin liu Jie liu Cheng Zhong Wenbin Hu Key Laboratory of Advanced Ceramics and Machining Technology(Ministry of Education) School of Materials Science and EngineeringTianjin UniversityTianjinChina Tianjin Key Laboratory of Composite and Functional Materials School of Materials Science and EngineeringTianjin UniversityTianjinChina Joint school of National University of singapore and Tianjin University TianjinChina International Campus of Tianjin University Binhai New CityFuzhouChina

silicon suboxide(siO_(x),x≈1)is promising in serving as an anode material for lithium-ion batteries with high capacity,but it has a low initial Coulombic efficiency(ICE)due to the irreversible formation of lithium silicates during the first *** this work,we modify siO_(x) by solid-phase Mg doping reaction using low-cost Mg powder as a reducing *** show that Mg reduces siO_(2) in siO_(x) to si and forms MgsiO_(3. or Mg_(2)siO_(4).The MgsiO_(3. or Mg_(2)siO_(4) are mainly distributed on the surface of siO_(x),which suppresses the irreversible lithium-ion loss and enhances the ICE of siO_(x).However,the formation of MgsiO_(3. or Mg_(2)siO_(4) also sacrifices the capacity of siO_(x).Therefore,by controlling the reaction process between Mg and siO_(x),we can tune the phase composition,proportion,and morphology of the Mg-doped siO_(x) and manipulate the *** obtain samples with a capacity of 1226 mAh g^(–1) and an ICE of 84.12%,which show significant improvement over carbon-coated siO_(x) without Mg *** the synergistical modification of both Mg doping and prelithiation,the capacity of siO_(x) is further increased to 1477 mAh g^(–1) with a minimal compromise in the ICE(83.77%).

关键词： initial Coulombic efficiency lithium-ion batteries magnesium doping prelithiation silicon suboxide

skill enhancement learning with knowledge distillation

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science China(Information sciences) 2024年第8期67卷 206-220页

作者： Naijun liu Fuchun sUN bin FANG Huaping liu Department of Computer science and Technology Tsinghua University

skill learning through reinforcement learning has significantly progressed in recent years. However, it often struggles to efficiently find optimal or near-optimal policies due to the inherent trial-and-error exploration in reinforcement learning. Although algorithms have been proposed to enhance skill learning efficacy, there is still much room for improvement in terms of skill learning performance and training stability. In this paper, we propose an algorithm called skill enhancement learning with knowledge distillation(sELKD), which integrates multiple actors and multiple critics for skill learning. sELKD employs knowledge distillation to establish a mutual learning mechanism among actors. To mitigate critic overestimation bias,we introduce a novel target value calculation method. We also perform theoretical analysis to ensure the convergence of sELKD. Finally, experiments are conducted on several continuous control tasks, illustrating the effectiveness of the proposed algorithm.

关键词： skill learning enhancement learning reinforcement learning knowledge distillation

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A visible-light-assisted Pd/TiO_(2)gas sensor with carbon nanotubes electrodes for trace formaldehyde detection

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Rare Metals 2024年第1期43卷 257-266页

作者： Can liu Qiao-Qiao Zou bin liu Yong Zhang school of Physics and Optoelectronics Xiangtan UniversityXiangtan 411105China Hunan Institute of Advanced sensing and Information Technology Xiangtan UniversityXiangtan 411105China school of Materials science and Engineering Xiangtan UniversityXiangtan 411105China

Owing to the ppb-level detection standard toward the toxic and harmful gas,the detection of trace gases has become an important subject in the field of indoor environment ***,the traditional resistive gas sensors hardly meet the requirement due to the weak signal generated by trace gas molecules that are difficult to ***,a visible-light-assisted Pd/TiO_(2)gas sensor is proposed to endow the effective detection of trace formaldehyde(HCHO)gas without heating *** from the enhanced photocatalytic properties of TiO_(2)by Pd decoration,the visible-light-assisted Pd/TiO_(2)gas sensor can detect the HCHO gas as low as80×10^(–9)at room *** successful preparation of nanoscale TiO_(2)sensing layer is facilitated by the ultrathin carbon nanotube interdigital electrode in the gas sensor,which avoids the discontinuity of the sensing layer caused by the excessive thickness of the traditional metal *** addition,the whole preparation process of the Pd/TiO_(2)gas sensor with carbon nanotube electrodes is compatible with mainstream CMOs fabrication technology,which is expected to realize the batch fabrication and micro-integrated application of gas *** is expected that our work can provide a new strategy for the batch preparation of high-performance trace HCHO gas sensors and their future applications in portable electronic devices such as smartphones.

关键词： Visible-light-assisted gas sensor Pd/TiO_(2) Trace HCHO detection Carbon nanotubes electrodes

Networking Observation and Applications of Chinese Ocean satellites

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空间科学学报 2024年第4期44卷 722-730页

作者： ZOU bin liu Yuxin National satellite Ocean Application service Beijing 100081 Key Laboratory of space Ocean Remote sensing and Application Ministry of Natural ResourcesBeijing 100081

This paper presents the networking observation capabilities of Chinese ocean satellites and their diverse applications in ocean disaster prevention,ecological monitoring,and resource *** the inaugural launch in 2002,China has achieved substantial advancements in ocean satellite technology,forming an observation system composed of the HY-1,HY-2,and HY-3.series *** satellites are integral to global ocean environmental monitoring due to their high resolution,extensive coverage,and frequent *** forward,China aims to further enhance and expand its ocean satellite capabilities through ongoing projects to support global environmental protection and sustainable development.

关键词： Chinese ocean satellites Networking observation Ocean forecasting Ocean disaster prevention and mitigation Ocean ecological monitoring Ocean resource development Polar monitoring Terrestrial applications

Effect of Al_(2)O_(3.fiber on twin intersections-induced dynamic recrystallization in fine-grained TiAl matrix composite

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Journal of Materials science & Technology 2024年第5期172卷 1-14页

作者： Yaofeng Luo Yan Wang Li Wang bin liu Yong liu state Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

Dynamic recrystallization(DRX)is of great significance for the thermomechanical processing and microstructural regulation of TiAl ***,the underlying DRX mechanism remains poorly *** this study,an Avrami kinetics model for DRX was established,which was capable of predicting the DRX fraction *** addition,the effect of Al_(2)O_(3.short fiber on the DRX mechanisms of TiAl matrix composite during the isothermal compression was investigated for the first *** re-sults showed that other than inhibiting DRX by particles in the TiAl matrix composites,the addition of Al_(2)O_(3.short fiber accelerated a novel DRX process,which was induced by twinning and twin intersec-tions(TDRX).Thus,this composite exhibited a higher DRX rate than that of the as-cast TiAl monolithic *** origin of the twin intersection and TDRX for the composite was *** stress concentration near the Al_(2)O_(3.fiber was above the critical shear stress for twinning and thus was favorable for the formation of twinning and twin *** high stored strain energy at the regions of twins and twin intersections provided the driving force for *** accelerated the grain refinement in the TiAl matrix near the Al_(2)O_(3.*** present findings would provide a new perspective on DRX mechanisms,and provide the scientific guidance for optimizing the microstructures of TiAl matrix composites.

关键词： TiAl matrix composite Al_(2)O_(3.fiber Twin intersection Dynamic recrystallization

Dual-Porosity Apparent Permeability Models of Unconventional Gas Migration Based on Biot’s Porous Media

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Acta Mechanica solida sinica 2024年第3期37卷 406-415页

作者： bin Gu Hongyuan liu Yiuwing Mai bing Wang school of Manufacturing science and Engineering Key Laboratory of Testing for Manufacturing ProcessMinistry of EducationSouthwest University of Science and TechnologyMianyang621010China school of Aerospace Mechanical and Mechatronic EngineeringThe University of SydneySydneyNSW2006Australia Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

stress-dependent permeability models are developed for the organic pores and inorganic cleats/fractures in unconventional gas reservoirs,which are modeled as Biot’s porous media of *** considering multiple flow mechanisms such as dynamic effects of gas flow and surface diffusion,apparent permeability models are obtained to investigate the characteristics of unconventional gas *** to the gas transfer in single-porosity reservoirs,the gas migration ability of cleats in dual-porosity stratums rarely changes while that of organic pores is greatly improved because cleats sustain major geomechanical shrinkage deformation when the pore pressure ***,the mass flux of reservoirs is dominated by the mass flux of cleats,which has a lower peak value,but a much longer production term than those in single-porosity reservoirs due to the interaction between organic pores and *** analysis is conducted to identify key factors significantly impacting mass flux in unconventional *** for the mass flux variation are also explored in terms of gas migration ability and pore pressure distribution.

关键词： Unconventional gas migration Apparent permeability Dual-porosity stress dependence Multiple flow mechanisms