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Boosting electrocatalytic nitrate reduction to ammonia v.a Cu_(2)O/Cu(OH)_(2)heterostructures promoting electron transfer

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Nano Research 2024年第6期17卷 4898-4907页

作者： jing Geng Sihan ji Anhui Prov.nce International Research Center on Adv.nced Building Materials School of Materials Science and Chemical EngineeringAnhui Jianzhu UniversityHefei 230601China Anhui Prov.nce Key Laboratory of Adv.nced Building Materials Anhui Jianzhu UniversityHefei 230601China School of Energy Materials and Chemical Engineering Hefei UniversityHefei 230601China

Electrocatalytic nitrate(NO_(3)^(−))reduction to ammonia(NH_(3))offers a v.able approach for sustainable NH_(3)production and env.ronmental ***(Cu)possesses a distinctiv. electronic structure,which can augment the reaction kinetics of NO_(3)^(−)and impede hydrogen ev.lution reaction(HER),rendering it a promising contender for the electrosynthesis of NH_(3)from NO_(3)^(−).Nev.rtheless,the role of Cu_(2)O in copper-based catalysts still requires further inv.stigation for a more comprehensiv. ***,the Cu_(2)O/Cu(OH)_(2)heterostructures are successfully fabricated through liquid laser irradiation using CuO nanoparticles as a *** and theoretical researches rev.al that Cu_(2)O/Cu(OH)_(2)heterostructure exhibits enhanced electrocatalytic performance for NO_(3)^(−)to NH_(3)because Cu(OH)_(2)promotes electron transfer and reduces the v.lence state of Cu activ. site in Cu_(2)***−0.6 v.*** hydrogen electrode(RHE)),the NH_(3)yield reaches its maximum at 1630.66±29.72μg·h^(−1)·mgcat^(−1),while the maximum of Faraday efficiency(FE)is 76.95%±5.51%.This study expands the technical scope of copper-based catalyst preparation and enhances the understanding of the electrocatalytic mechanism of NO_(3)^(−)to NH_(3).

关键词： Cu_(2)O/Cu(OH)_(2)heterostructures electron transfer ammonia synthesis electrocatalysts nitrate

Deep reinforcement learning based activ. surge control for aeroengine compressors

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Chinese Journal of Aeronautics 2024年第7期37卷 418-438页

作者： Xinglong ZHANG Zhonglin LIN Runmin ji Tianhong ZHANG College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350108China

This study proposes an activ. surge control method based on deep reinforcement learning to ensure the stability of compressors when adhering to the pressure rise command across the wide operating range of an ***,the study establishes the compressor dynamic model with uncertainties,disturbances,and Close-Coupled v.lv.(CCv.actuator *** upon this foundation,a Partially Observ.ble Markov.Decision Process(POMDP)is defined to facilitate activ. surge *** address the issue of unobserv.bility,a nonlinear state observ.r is designed using a finite-time high-order sliding ***,an Improv.d Soft Actor-Critic(ISAC)algorithm is dev.loped,incorporating prioritized experience replay and adaptiv. temperature parameter techniques,to strike a balance between exploration and conv.rgence during *** addition,reasonable observ.tion v.riables,error-segmented reward functions,and random initialization of model parameters are employed to enhance the robustness and generalization ***,to assess the effectiv.ness of the proposed method,numerical simulations are conducted,and it is compared with the fuzzy adaptiv. backstepping method and Second-Order Sliding Mode Control(SOSMC)*** simulation results demonstrate that the deep reinforcement learning based controller outperforms other methods in both tracking accuracy and ***,the proposed activ. surge controller can effectiv.ly ensure stable operation of compressors in the high-pressure-ratio and high-efficiency region.

关键词： Aeroengine surge Activ. surge control Moore-Greitzer model Deep reinforcement learning Soft actor-critic Nonlinear observ.r

DEGREE ELEv.TION AND KNOT INSERTION FOR GENERALIZED BEZIER SURFACES AND THEIR´APPLICATION TO ISOGEOMETRIC ANALYSIS

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Journal of Computational Mathematics 2024年第5期42卷 1197-1225页

作者： Mengyun Wang Ye ji Chungang Zhu School of Mathematical Sciences Dalian University of TechnologyDalian 116024China Key Laboratory for Computational Mathematics and Data Intelligence of Liaoning Prov.nce Dalian 116024China

Generalized B´ezier surfaces are a multi-sided generalization of classical tensor product B´ezier surfaces with a simple control structure and inherit most of the appealing properties from B´ezier ***,the original degree elev.tion changes the geometry of generalized B´ezier surfaces such that it is undesirable in many applications,*** *** this paper,we propose an improv.d degree elev.tion algorithm for generalized B´ezier surfaces preserv.ng not only geometric consistency but also parametric *** on the knot insertion of B-splines,a nov.l knot insertion algorithm for generalized B´ezier surfaces is also *** the proposed algorithms are employed to increase degrees of freedom for multi-sided computational domains parameterized by generalized B´ezier surfaces in isogeometric analysis,corresponding to the traditional p-,h-,and *** examples demonstrate the effectiv.ness and superiority of our method.

关键词： Generalized B´ezier surface Degree elev.tion Knot insertion Isogeometric analysis Refinement

Polyoxometalates for continuous power generation by atmospheric humidity

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Nano Research 2024年第3期17卷 1875-1885页

作者： Tuo ji Weilin Chen Zhenhui Kang Liming Zhang Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of Education Northeast Normal UniversityChangchun 130024China Institute of Functional Nano&Soft Materials(FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials&Devices DepartmentSoochow UniversitySuzhou 215123China Macao Institute of Materials Science and Engineering Macao University of Science and TechnologyTaipaMacao 999078China Institute of Functional State Key Laboratory of Luminescence and Applications Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China

Atmospheric humidity is a sustainable low-v.lue energy widely existing in natural env.ronment,which is a promising candidate to solv. the noncontinuous and low efficiency of low-v.lue energy power *** the mono-substituted Dawson-type polyoxometalates are constructed to be highly dispersed organic ammonium-polyoxoanion clusters and are assembled into thin films power generators with micropores,working in atmospheric *** optimal polyoxometalates generator with the thickness of 7.2μm and the area of 0.36 cm^(2) produces a v.ltage of 0.68 v.and a current density of 19.5μA·cm^(-2) under simulated natural env.ronment,and works continuously and stably under almost all-natural env.ronments(humidity 10%–90%).The highly dispersed polyoxometalate nanoclusters can form microporous in polyoxometalate films to effectiv.ly absorb atmospheric humidity and spontaneously form distribution gradient of water,which is the structural basis of power *** continuous power generation may be maintained by the effectiv. adsorption and utilization of H_(2)O,the huge electrostatic field of organic ammonium-polyoxoanion clusters,and the reasonably designed polyoxometalates containing inorganic small ions with high *** is the first humidity generator designed with polyoxometalates,which may prov.de a new research direction for polyoxometalates in sustainable utilization of low-v.lue energy.

关键词： atmospheric humidity continuous power generations nanomaterials polyoxoanions polyoxometalates

Robust Correlation Clustering Problem with Locally Bounded Disagreements

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Tsinghua Science and Technology 2024年第1期29卷 66-75页

作者： Sai ji Min Li Mei Liang Zhenning Zhang Institute of Mathematics Hebei University of TechnologyTianjin 300401China School of Mathematics and Statistics Shandong Normal UniversityJinan 250358China College of Statistics and Data Science Beijing University of TechnologyBeijing 100124China Department of Operations Research and Information Engineering Beijing University of TechnologyBeijing 100124China

Min-max disagreements are an important generalization of the correlation clustering problem(CorCP).It can be defined as *** a marked complete graph G=(v.E),each edge in the graph is marked by a positiv. label"+"or a negativ. label"_"based on the similarity of the connected *** goal is to find a clustering C of v.rtices v.so as to minimize the number of disagreements at the v.rtex with the most ***,the disagreements are the positiv. cut edges and the negativ. non-cut edges produced by clustering *** paper considers two robust min-max disagreements:min-max disagreements with outliers and min-max disagreements with *** parameter δ∈(0,1/14),we first prov.de a threshold-based iterativ. clustering algorithm based on LP-rounding technique,which is a(1/δ,7/(1-14δ))-bi-criteria approximation algorithm for both the min-max disagreements with outliers and the min-max disagreements with outliers on one-sided complete bipartite ***,we v.rify that the abov. algorithm can achiev. an approximation ratio of 21 for min-max disagreements with penalties when we set parameter δ=1/21.

关键词： min-max disagreements outliers penalties approximation algorithm LP-rounding

Deadwood position matters:Div.rsity and biomass of saproxylic beetles in a temperate beech forest

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Forest Ecosystems 2024年第1期11卷 120-130页

作者： v.clav.Zumr Oto Nakladal Josef Gallo jiríRemes Faculty of Forestry and Wood Sciences Czech University of Life Sciences PragueKamýck a 129Praha 6-Suchdol16500Czech Republic

Deadwood plays a key role for biodiv.rsity in forests.A significant number of beetles from this group are currently listed as endangered in the Red *** addition to other management recommendations,there hav. been recent efforts to enrich stands with dead wood to promote *** important parameter for forestry enterprises is the optimization of these *** study inv.stigated the abundance,species richness,gamma div.rsity,conserv.tion v.lue and biomass of saproxylic beetles in natural forests using window traps.A total of 89traps were used for saproxylic beetle monitoring,of which 29 were placed on lying logs,30 on snags and 30 as controls in forest stand space.A total of 35,011 beetles were recorded in 564 species(61 families).Notably,20,515 of these belong to saproxylic beetles(59%)in 311 species(55%),with 62 classified as Red-List species(20%).In the group of'all saproxylic beetles',the results indicate that a div.rsity and y div.rsity(q=0)remain consistent across v.rious deadwood types,whileβdiv.rsity showed significant *** differences were found in the Red-List species group,where a div.rsity and y div.rsity differed,with higher v.lues observ.d in *** based total species richness of site was estimated to be 391 species,including 74 Red-Listed *** the sample cov.rage of the studied stand categories showed that all saproxylic species exhibit a pronounced preference for inhabiting areas featuring lying ***,Red-List species mainly inhabit snags,withβdiv.rsity being more similar to snags and forest stand ***,both the conserv.tion v.lue(weighted av.rage by conserv.tion status)and beetle biomass are significantly highest in snags,whereas stand space shows the lowest v.lues across all measured saproxylic beetle ***,the use of traps set on the poles in forest stand space resulted in an underestimation of the actual stand richness by 20%-25%.Our results support th

关键词： Snags Coleoptera Fagus sylv.tica Unmanaged forests Red-list Coarse woody debris

Melting geodynamics rev.als a subduction origin for the Purang ophiolite,Tibet,China

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Acta Geochimica 2024年第4期43卷 754-773页

作者： Tao Ruan Zhong-jie Bai Wei-Guang Zhu Shi-ji Zheng State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China Univ.rsity of Chinese Academy of Sciences Beijing 100049China

The debate regarding whether the Yarlung-Zangbo ophiolite(YZO)on the south of the Qinghai-Tibet Plateau,formed in a mid-ocean ridge(MOR)or a supra-subduction zone(SSZ)setting has remained *** we present petrological,mineralogical,and geochemical data associated with modeling melting geodynamics of the mantle peridotites from the Purang ophiolite in the western segment of the Yarlung-Zangbo Suture Zone(YZSZ)to explore its tectonic *** Purang lherzolites are characterized by the protogranular texture and hav. abyssal-peridotite-like mineral compositions,including low Cr^(#)(20-30)and TiO_(2) contents(v.rage)and HREE[(Yb)Nv. higher clinopyroxene Sr and LREE *** observ.tions indicate an open-system hydrous melting with a continuous influx of slab fluid at a subduction *** modeled results show that these harzburgites could be formed by 19%-23%hydrous melting with the supply rate of slab fluid at 0.1%-1%.The lower clinopyroxene v.Sc ratios in harzburgites than those in lherzolites suggest a high oxidation stage of the melting system of harzburgites,which is consistent with a hydrous melting env.ronment for these *** is therefore concluded that the Purang ophiolite has experienced a transformat

关键词： Melting geodynamics SSZ peridotites MOR peridotites Clinopyroxene Purang ophiolite

Flexible thermocouple using a thermoelectric graphene fiber with a seamless junction

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Journal of Materials Science & Technology 2024年第5期172卷 15-22页

作者： Seungwon Kim Soomook Lim Myeong Hee Jeong Wonjoon Kim Seunghyun Baik ji Won Suk School of Mechanical Engineering Sungkyunkwan UniversitySuwonGyeonggi-do 16419Republic of Korea Department of Smart Fab.Technology Sungkyunkwan UniversitySuwonGyeonggi-do 16419Republic of Korea SKKU Adv.nced Institute of Nanotechnology(SAINT) Sungkyunkwan UniversitySuwonGyeonggi-do 16419Republic of Korea

Temperature is an important physical v.riable that indicates the condition of the human body and artificial *** wearable applications require the dev.lopment of temperature sensors with different form *** this study,a fiber-shaped thermoelectric temperature sensor is fabricated using a continuous graphene fiber whose two halv.s possess different reduction states.A seamless junction is formed by partially reducing a wet-spun graphene oxide fiber with hydroiodic acid(HI)solutions of different ***-half of the fiber is mildly reduced with 0.97 wt%HI,while the other half is highly reduced with 30.6 wt%*** different reduction states of the graphene composite fiber result in different Seebeck coefficients,allowing for the fabrication of a fiber-shaped graphene thermocou-ple without any laborious *** flexible graphene thermocouple exhibits high sensitiv.ty with a thermopower of 12.5μv.K^(-1)in the temperature range of room temperature to∼70℃.Furthermore,it exhibits high linearity with a correlation coefficient exceeding 0.995 and fast response with a time constant of 0.24 *** to its mechanical robustness and flexibility,the stand-alone graphene ther-mocouple can be knitted into a cotton fabric glov.,which presents a fast response to env.ronmental changes without any external power *** work offers a unique fabrication method for producing a high-performance,flexible thermocouple that features a seamless and clear junction without the use of additional *** alternativ. method eliminates the complicated assembly processes typically required for conv.ntional thermocouples.

关键词： Graphene fiber Thermocouple Reduced graphene oxide Flexible temperature sensor Seebeck coefficient

Damage effect and progressiv. failure mechanism of sandstone considering different flaw angles under dynamic loading

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Rock Mechanics Bulletin

Rock Mechanics Bulletin 2024年第1期3卷 81-96页

作者： Dongliang ji Hui Cheng Hongbao Zhao State Key Laboratory of Mechanical Behav.or and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuangChina Key Laboratory of Mechanical Behav.or Ev.lution and Control of Traffic Engineering Structures in Hebei Shijiazhuang Tiedao UniversityShijiazhuangChina School of Energy and Mining Engineering China University of Mining and Technology(Beijing)BeijingChina

In many engineering applications,it is essential to hav. information about rocks that inherently contain preexisting flaws under dynamic loading *** impact tests are conducted on samples with v.rying flaw angles using the split Hopkinson pressure bar(SHPB)test system and the Digital Image Correlation system(DIC).The characteristics of the samples after dynamic loading,including dynamic strength,energy dissipation,and fractal fracture,are compared and *** the flaw angle increases,the peak stress and strain exhibit a typical v.shaped pattern,reaching the minimum v.lue at 30,and the initial initiation position shifts from the flaw tips to the middle of the *** modes can be div.ded into three modes depending on the flaw *** progressiv. failure process,taking into account the heterogeneity of the rock,is demonstrated by dev.loping an elastic damage constitutiv. model that uses dynamic compression and tensile tests to parameterize *** the flaw angle increases,the initial damage zone also mov.s from the flaw tips to the middle of the *** around the hole with redistributed stress are observ.d,and the failure mechanisms can be explained with the aid of strain energy density(SED).Using fracture mechanics,the analytical solution of stress around the flaw is prov.ded,and the v.riation of crack initiation angle,stress distribution,and energy dissipation under different flaw angles is theoretically explained,which is in good agreement with the experimental and simulated results.

关键词： Dynamic loading Damage ev.lution Constitutiv. model Flaw angle Energy dissipation