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Mechanical behaviors of warm and ice-rich frozen soil stabilized with sulphoaluminate cement

Journal of Mountain Science 2024年第1期21卷 335-345页

作者： WANG Honglei zhang Hu zhang Jianming zhang Qi YIN Zhenhua State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China School of Civil Engineering and Transportation Northeast Forestry UniversityHarbin 150040China National Key Laboratory of Green and Long-Life Road Engineering in Extreme Environment CCCC First Highway Consultants Co.LtdXi'an 710065China Railway Engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China

The warm and ice-rich frozen soil is characterized by high unfrozen water content, low shear strength and large compressibility, which is unreliable to meet the stability requirements of engineering infrastructures and foundations in permafrost regions. In this study, a novel approach for stabilizing the warm and ice-rich frozen soil with sulphoaluminate cement was proposed based on chemical stabilization. The mechanical behaviors of the stabilized soil, such as strength and stress-strain relationship, were investigated through a series of triaxial compression tests conducted at -1.0℃, and the mechanism of strength variations of the stabilized soil was also explained based on scanning electron microscope test. The investigations indicated that the strength of stabilized soil to resist failure has been improved, and the linear Mohr-Coulomb criteria can accurately reflect the shear strength of stabilized soil under various applied confining pressure. The increase in both curing age and cement mixing ratio were favorable to the growth of cohesion and internal friction angle. More importantly, the strength improvement mechanism of the stabilized soil is attributed to the formation of structural skeleton and the generation of cementitious hydration products within itself. Therefore, the investigations conducted in this study provide valuable references for chemical stabilization of warm and ice-rich frozen ground, thereby providing a basis for in-situ ground improvement for reinforcing warm and ice-rich permafrost foundations by soil-cement column installation.

关键词： Permafrost regions Frozen soil Mechanical behavior Chemical stabilization Ground improvement Ground modification

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A robust joint frequency spectrum and power allocation strategy in a coexisting radar and communication system

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Chinese Journal of Aeronautics 2024年第10期37卷 393-409页

作者： Haowei zhang Weijian LIU Qun zhang Taiyong FEI Air and Missile Defense School Air Force Engineering UniversityXi’an 710051China Air Force Early Warning Academy Wuhan 410039China Information and Navigation School Air Force Engineering UniversityXi’an 710082China

The resource allocation technique is of great significance in achieving frequency spectrum coexistence in Joint Radar-Communication(JRC)systems,by which the problem of radio frequency spectrum congestion can be well alleviated.A Robust Joint Frequency Spectrum and Power Allocation(RJFSPA)strategy is proposed for the Coexisting Radar and Communication(CRC)***,we consider the uncertainty of target Radar Cross Section(RCS)and communication channel gain to formulate a bi-objective optimization *** joint probabilities that the Crame´r-Rao Lower Bound(CRLB)of each target satisfying the localization accuracy threshold and the Communication Data Ratio(CDR)of each user satisfying the communication threshold are simultaneously maximized,under the constraint of the total power budget.A Three-Stage Alternating Optimization Method(TSAOM)is proposed to obtain the Best-Known Pareto Subset(BKPS)of this problem,where the frequency spectrum,radar power,and communicator power are allocated using the greedy search and standard convex optimization methods,*** results confirm the effectiveness of the proposed RJFSPA strategy,compared with the resource allocation methods in a uniform manner and that ignores the *** efficiency of the TSAOM is also verified by the comparison with the exhaustive search-based method.

关键词： Radar and communication system Bi-objective optimization Resource allocation Cramér-Rao lower bound Communication data ratio

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Materials design and preparation of ultrathin two-dimensional metal halide perovskites

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Nano Research 2024年第7期17卷 6231-6246页

作者： Xiaomin zhang Sihan Zhao Junran zhang Lin Wang School of Flexible Electronics(Future Technologies)and Institute of Advanced Materials Key Laboratory of Flexible ElectronicsJiangsu National Synergetic Innovation Center for Advanced MaterialsSchool of Physical and Mathematical SciencesNanjing Tech UniversityNanjing 211816China

Metal halide perovskites(MHPs)have emerged as highly promising candidates for the next generation of photonics and optoelectronic devices,owing to their prominent optical and excitonic properties,as well as the convenience of ***,ultrathin two-dimensional(2D)MHPs,which are generally prepared by exfoliation,solution growth,and chemical vapor deposition method,have attracted dramatically increasing attentions owing to their combined features of ultrathin 2D morphology and superior performance of *** the growing interest in ultrathin 2D MHPs,there is currently a lack of a comprehensive and systematic overview of the distinct advantages offered by each growth method for producing these *** review critically assesses the preliminary studies on the materials design and preparation of ultrathin ***,it explores heterostructures based on ultrathin MHPs and offers insights into the challenges and opportunities that lie ahead for this enticing class of 2D materials.

关键词： ultrathin perovskites material preparation exfoliation solution growth chemical vapor deposition

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CF-DAN: Facial-expression recognition based on cross-fusion dual-attention network

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Computational Visual Media 2024年第3期10卷 593-608页

作者： Fan zhang Gongguan Chen Hua Wang Caiming zhang Shandong Technology and Business University Shandong 264005China School of Information and Electrical Engineering Ludong UniversityYantai 264025China Shangdong University Shandong 250100China

Recently, facial-expression recognition (FER)has primarily focused on images in the wild, includingfactors such as face occlusion and image blurring, ratherthan laboratory images. Complex field environmentshave introduced new challenges to FER. To addressthese challenges, this study proposes a cross-fusion dualattention network. The network comprises three parts:(1) a cross-fusion grouped dual-attention mechanism torefine local features and obtain global information;(2) aproposed C2 activation function construction method,which is a piecewise cubic polynomial with threedegrees of freedom, requiring less computation withimproved ﬂexibility and recognition abilities, whichcan better address slow running speeds and neuroninactivation problems;and (3) a closed-loop operationbetween the self-attention distillation process andresidual connections to suppress redundant informationand improve the generalization ability of the *** recognition accuracies on the RAF-DB, FERPlus,and AffectNet datasets were 92.78%, 92.02%, and63.58%, respectively. Experiments show that this modelcan provide more effective solutions for FER tasks.

关键词： facial-expression recognition(FER) cubic polynomial activation function dualattention mechanism interactive learning self-attention distillation

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Bifunctional passivation by lewis-base molecules for efficient printable mesoscopic perovskite solar cells

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Journal of Energy Chemistry 2024年第9期96卷 177-184页

作者： Hang Yang Jianhong Zhao Xiaodong Ren Tong Zhou Henbing zhang Weilong zhang Jin zhang Guangzhi Hu Yuming zhang Wen-Hua zhang Qingju Liu Yunnan Key Laboratory for Micro/Nano Materials & Technology National Center for International Research on Photoelectric and Energy Materials School of Materials and Energy Yunnan UniversityKunming 650091YunnanChina Institute for Ecological Research and Pollution Control of Plateau Lakes School of Ecology and Environmental Science Yunnan UniversityKunming 650091YunnanChina

Printable mesoscopic perovskite solar cells(PM-PSCs)possess notable merits in terms of cost-effectiveness,easy manufacturing,and large scale ***,the absence of a hole transport layer contributes to the exacerbation of carrier recombination,and the defects between the perovskite and electron transport layer(ETL)interfaces significantly decrease the efficiency of the *** this study,a bifunctional surface passivation approach is proposed by applying a thioacetamide(TAA)surfactant on the mesoporous TiO_(2)*** results demonstrate that TAA molecules could interact with TiO_(2),thereby diminishing the oxygen vacancy ***,the amino group and sulfur atoms in TAA molecules act as Lewis base to effectively passivate the uncoordinated Pb^(2+)in perovskite and improve the morphology of perovskite,and decrease the trap-state density of *** TAA passivation mechanism improves the alignment of energy levels between TiO_(2)and perovskite,facilitating electron transport and reducing carrier ***,the TAA-passivated device achieved a champion power conversion efficiency(PCE)of 17.86%with a high fill factor(FF)of 79.16%and an open-circuit voltage(V_(OC))of 0.971 *** investigation presents a feasible strategy for interfacial passivation of the ETL to further improve the efficiency of PM-PSCs.

关键词： Perovskite solarcells Carbon electrode Thioacetamide Interfacial passivation

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Bayesian ensemble methods for predicting ground deformation due to tunnelling with sparse monitoring data

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Underground Space 2024年第3期16卷 79-93页

作者： Zilong zhang Tingting zhang Xiaozhou Li Daniel Dias School of Civil Engineering Central South UniversityChangshaHunan 410075China Laboratory 3SR Grenoble Alpes UniversityCNRS UMR 5521Grenoble 38000France

Numerous analytical models have been developed to predict ground deformations induced by tunneling,which is a critical issue in tunnel ***,the accuracy of these predictions is often limited by errors and uncertainties resulting from model selection and parameter fittings,given the paucity of monitoring data in field *** paper proposes a novel approach to estimate tunnelling-induced ground deformations by applying Bayesian model averaging to several representative prediction *** accounting for both model and parameter uncertainties,this approach enables more realistic predictions of ground deformations than individual ***,our results indicate that the Gonzalez-Sagaseta model outperforms other models in predicting ground surface settlements,while the Loganathan-Poulos model is most suitable for predicting subsurface vertical and horizontal ***,our analysis reveals that when monitoring data are sparse,model uncertainties may contribute up to 78.7%of the total ***,obtaining sufficient data for parameter fitting is crucial for accurate *** proposed method in this study offers a more realistic and efficient prediction of tunnelling-induced ground deformations.

关键词： Tunnelling-induced ground deformations Sparse data Model uncertainties Bayesian model averaging

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A hierarchical enhanced data-driven battery pack capacity estimation framework for real-world operating conditions with fewer labeled data

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Journal of Energy Chemistry 2024年第4期91卷 417-432页

作者： Sijia Yang Caiping zhang Haoze Chen Jinyu Wang Dinghong Chen Linjing zhang Weige zhang National Active Distribution Network Technology Research Center(NANTEC) Beijing Jiaotong UniversityBeijing 100044China

Battery pack capacity estimation under real-world operating conditions is important for battery performance optimization and health management,contributing to the reliability and longevity of batterypowered ***,complex operating conditions,coupling cell-to-cell inconsistency,and limited labeled data pose great challenges to accurate and robust battery pack capacity *** address these issues,this paper proposes a hierarchical data-driven framework aimed at enhancing the training of machine learning models with fewer labeled *** traditional data-driven methods that lack interpretability,the hierarchical data-driven framework unveils the“mechanism”of the black box inside the data-driven framework by splitting the final estimation target into cell-level and pack-level intermediate targets.A generalized feature matrix is devised without requiring all cell voltages,significantly reducing the computational cost and memory *** generated intermediate target labels and the corresponding features are hierarchically employed to enhance the training of two machine learning models,effectively alleviating the difficulty of learning the relationship from all features due to fewer labeled data and addressing the dilemma of requiring extensive labeled data for accurate *** only 10%of degradation data,the proposed framework outperforms the state-of-the-art battery pack capacity estimation methods,achieving mean absolute percentage errors of 0.608%,0.601%,and 1.128%for three battery packs whose degradation load profiles represent real-world operating *** high accuracy,adaptability,and robustness indicate the potential in different application scenarios,which is promising for reducing laborious and expensive aging experiments at the pack level and facilitating the development of battery technology.

关键词： Lithium-ion battery pack Capacity estimation Label generation Multi-machine learning model Real-world operating

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Strategies to achieve effective nitrogen activation

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Carbon Energy 2024年第5期6卷 137-163页

作者： Bin Chang Huabin zhang Shuhui Sun Gaixia zhang KAUST Catalysis Center(KCC) King Abdullah University of Science and Technology(KAUST)ThuwalKingdom of Saudi Arabia Institut National de la Recherche Scientifique(INRS) CentreÉnergie Matériaux TélécommunicationsVarennesQuébecCanada Department of Electrical Engineering École de Technologie Supérieure(ÉTS)MontréalQuébecCanada

Ammonia serves as a crucial chemical raw material and hydrogen energy *** electrocatalytic nitrogen reduction reaction(NRR),powered by renewable energy,has attracted tremendous interest during the past few *** some achievements have been revealed in aqueous NRR,significant challenges have also been *** activity and selectivity are fundamentally limited by nitrogen activation and competitive hydrogen *** review focuses on the hurdles of nitrogen activation and delves into complementary strategies,including materials design and system optimization(reactor,electrolyte,and mediator).Then,it introduces advanced interdisciplinary technologies that have recently emerged for nitrogen activation using high-energy physics such as plasma and *** a better understanding of the corresponding reaction mechanisms in the coming years,these technologies have the potential to be extended in further *** review provides further insight into the reaction mechanisms of selectivity and stability of different reaction *** then recommend a rigorous and detailed protocol for investigating NRR performance and also highlight several potential research directions in this exciting field,coupling with advanced interdisciplinary applications,in situ/operando characterizations,and theoretical calculations.

关键词： activation via mediators catalyst optimization electrochemical nitrogen fixation high-energy activation of nitrogen nitrogen

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Protective benefit of folded linear HDPE board sand fences along the Golmud-Korla Railway,China:Field observation and wind tunnel study

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Journal of Mountain Science 2024年第7期21卷 2206-2219页

作者： zhang Kai TIAN Jianjin WANG Zhenghui zhang Hailong zhang Xingxin College of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China College of Civil Engineering Chongqing UniversityChongqing 400045China

The Milan Gobi area of the Golmud-Korla Railway in northwest China is located in the lower dispersal area of the mountain pass and has strong winds with evident double wind direction *** study introduced a novel sand fence deployment technique,termed‘folded linear deployment',designed to position the sand fence orthogonally to the two predominant wind directions for optimal *** study used wind tunnel and field tests to evaluate the wind and sand flow characteristics,as well as the windproof and sandresistant performance of folded linear HDPE(Highdensity polyethylene)board sand *** results suggest that the airflow around the fence creates clear zoning *** deceleration area on the BSF(backwind side of the sand fence)is much larger than that on the DSF(downwind side of the sand fence).Thus,sand particles are primarily deposited on the *** different wind speeds,the airflow at 2 and 5 h on the DSF is not *** WSP(wind speed profile)presents a logarithmic *** airflow is disturbed at 1-20 h on the BSF,and the WSP gradually deviates from the logarithmic ***,as the airflow moves away from the fence,the WSP gradually approaches a logarithmic ***,the WPE(windproof efficiency)and SRE(sand-resistant efficiency)of the sand fence exceed 80%.In addition,the results of wind tunnel tests are compared with those of field *** overall dispersion is good,and the best dispersion is found at z/H=2.00,indicating good agreement between the two test *** study provides a scientific basis for the design of sand hazard control measures,similar to the railway project in the Gobi Gale area.

关键词： Folded linear HDPE board sand fence Double wind direction Gobi area Protection benefit

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Interface Engineering of Titanium Nitride Nanotube Composites for Excellent Microwave Absorption at Elevated Temperature

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Nano-Micro Letters 2024年第9期16卷 147-160页

作者： Cuiping Li Dan Li Shuai zhang Long Ma Lei zhang Jingwei zhang Chunhong Gong College of Chemistry and Molecular Sciences Henan UniversityKaifeng 475004People’s Republic of China National and Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials Henan UniversityKaifeng 475004People’s Republic of China

Currently,the microwave absorbers usually suffer dreadful electromagnetic wave absorption(EMWA)performance damping at elevated temperature due to impedance mismatching induced by increased conduction ***,the development of high-performance EMWA materials with good impedance matching and strong loss ability in wide temperature spectrum has emerged as a top ***,due to the high melting point,good electrical conductivity,excellent environmental stability,EM coupling effect,and abundant interfaces of titanium nitride(TiN)nanotubes,they were designed based on the controlling kinetic diffusion procedure and Ostwald ripening *** from boosted heterogeneous interfaces between TiN nanotubes and polydimethylsiloxane(PDMS),enhanced polarization loss relaxations were created,which could not only improve the depletion efficiency of EMWA,but also contribute to the optimized impedance matching at elevated ***,the TiN nanotubes/PDMS composite showed excellent EMWA performances at varied temperature(298-573 K),while achieved an effective absorption bandwidth(EAB)value of 3.23 GHz and a minimum reflection loss(RLmin)value of−44.15 dB at 423 *** study not only clarifies the relationship between dielectric loss capacity(conduction loss and polarization loss)and temperature,but also breaks new ground for EM absorbers in wide temperature spectrum based on interface engineering.

关键词： TiN nanotubes Interface engineering Polarization loss Impedance matching Electromagnetic wave absorption performance

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