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Supercritical CO_(2) Cycles for Nuclear-Powered Marine Propulsion:Preliminary Conceptual Design and Off-Design Performance Assessment

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Journal of Thermal Science 2024年第1期33卷 328-347页

作者： LI Zhaozhi shi Mingzhu SHAO Yingjuan zhong Wenqi Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China

Using the efficient,space-saving,and flexible supercritical carbon dioxide(sCO_(2)) Brayton cycle is a promising approach for improving the performance of nuclear-powered *** purpose of this paper is to design and compare sCO_(2) cycle power systems suitable for nuclear-powered *** the characteristics of nuclear-powered ships,this paper uses different indicators to comprehensively evaluate the efficiency,cost,volume,and partial load performance of several nuclear-powered sCO_(2) *** load-following strategies are also designed and *** results show that the partial cooling cycle is most suitable for nuclear-powered ships because it offers both high thermal efficiency and low volume and cost,and can maintain relatively high thermal efficiency at partial ***,the new load-following strategy that adjusts the turbine speed can keep the compressor away from the surge line,making the cycle more flexible and efficient compared to traditional inventory and turbine bypass strategies.

关键词： supercritical CO_(2)cycle nuclear marine propulsion off-design performance

Wintertime Arctic Sea-Ice Decline Related to Multi-Year La Niña Events

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Advances in Atmospheric Sciences 2024年第9期41卷 1680-1690页

作者： Wenxiu zhong Qian shi Qinghua YANG Jiping LIU Song YANG School of Atmospheric Sciences Sun Yat-sen Universityand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Sun Yat-sen UniversityGuangzhou 510275China

Arctic sea ice has undergone a significant decline in the Barents-Kara Sea(BKS)since the late *** studies have shown that the decrease in sea ice caused by increased poleward moisture transport is modulated by tropical sea temperature changes(mainly referring to La Niña events).The occurrence of multi-year La Niña(MYLA)events has increased significantly in recent decades,and their impact on Arctic sea ice needs to be further *** this study,we investigate the relationship between sea-ice variation and different atmospheric diagnostics during MYLA and other La Niña(OTLA)*** decline in BKS sea ice during MYLA winters is significantly stronger than that during OTLA *** is because MYLA events tend to be accompanied by a warm Arctic-cold continent pattern with a barotropic high pressure blocked over the Urals ***,more frequent northward atmospheric rivers intrude into the BKS,intensifying longwave radiation downward to the underlying surface and melting the BKS sea ***,in the early winter of OTLA years,a negative North Atlantic Oscillation presents in the high latitudes of the Northern Hemisphere,which obstructs the atmospheric rivers to the south of *** infer that such a different response of BKS sea-ice decline to different La Niña events is related to stratospheric *** the rapid climate changes in the past,more frequent MYLA events may account for the substantial Arctic sea-ice loss in recent decades.

关键词： Arctic sea ice multi-year ENSO Ural blocking atmospheric river Barents-Kara Sea

X-ray-activated Bi^(3.)/Pr^(3.)co-doped LiYGeO_4 phosphor with UV and NIR dual-emissive persistent luminescence

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Journal of Rare Earths 2024年第5期42卷 955-961,I0005页

作者： Xianggui Yin Hongyun zhong Lin Liu Junpeng shi Xia Sun Yun Zhang State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou350002China Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of SciencesXiamen361021China Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou350108China

X-ray-activated luminescence materials have broad application prospects in photodynamic therapy of deep *** them,X-ray-activated persistent luminescence materials(PLMs)exhibiting multiple emission peaks have drawn extensive attention for the ir capacity to achieve a combination of bioimaging and therapeutic ***,we developed a novel PLM,LiYGeO_4:Bi^(3.),Pr^(3.),that simultaneously exhibits UV and NIR dual persistent luminescence(PersL)emissions after irradiation by *** material can be re peatedly excited by X-ray and emits similar lumine scence intensity every time,which shows good PersL *** addition,LiYGeO_4:Bi^(3.),Pr^(3.)exhibits photostimulated PersL properties by stimulation with a red light-emitting diode(LED)or NIR laser after long-term *** work provides a new choice of X-ray-excited PLMs with UV and NIR dual emission and the novel phosphor shows promise as a potential candidate for the integration of treatment and diagnosis of deep tumors.

关键词： Co-doping X-ray-activated Dual emissions Persistent luminescence Rare earths

A residual denoising and multiscale attention-based weighted domain adaptation network for tunnel boring machine main bearing fault diagnosis

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Science China(Technological Sciences) 2024年第8期67卷 2594-2618页

作者： zhong Tao QIN ChengJin shi Gang ZHANG ZhiNan TAO JianFeng LIU ChengLiang State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

As a critical component of a tunnel boring machine(TBM),the precise condition monitoring and fault analysis of the main bearing is essential to guarantee the safety and efficiency of the TBM cutter ***,under conditions of strong noise and complex working environments,traditional signal decomposition and machine learning methods struggle to extract weak fault features and achieve high fault classification *** address these issues,we propose a novel residual denoising and multiscale attention-based weighted domain adaptation network(RDMA-WDAN)for TBM main bearing fault *** approach skillfully designs a deep feature extractor incorporating residual denoising and multiscale attention modules,achieving better domain adaptation despite significant domain *** residual denoising component utilizes a convolutional block to extract noise features,removing them via residual ***,the multiscale attention module uses a 4-branch convolution and 3.pooling strategy-based channel–spatial attention mechanism to extract multiscale features,concentrating on deep fault *** training,a weighting mechanism is introduced to prioritize domain samples with clear fault *** optimizes the deep feature extractor to obtain common features,enhancing domain adaptation.A low-speed and heavy-loaded bearing testbed was built,and fault data sets were established to validate the proposed *** experiments show that in noise domain adaptation tasks,proposed the RDMA–WDAN significantly improves target domain classification accuracy by 42.544%,23.088%,43.13.%,16.3.4%,5.022%,and 9.23.%over dense connection network(DenseNet),squeeze–excitation residual network(SE-ResNet),antinoise multiscale convolutional neural network(ANMSCNN),multiscale attention module-based convolutional neural network(MSAMCNN),domain adaptation network,and hybrid weighted domain adaptation(HWDA).In combined noise and working condition domain a

关键词： tunnel boring machine(TBM) main bearing fault diagnosis domain adaptation antinoise cross working RDMA-WDAN

Novel CoP/CoMoP_(2) heterojunction with nanoporous structure as an efficient electrocatalyst for hydrogen evolution

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Nano Research 2024年第5期17卷 3693-3699页

作者： Lili Zhang Xinxing shi Aijiao Xu Wenwu zhong Jitang Zhang shijie Shen Zhejiang Provincial Key Laboratory for Cutting Tools Taizhou UniversityJiaojiang 318000China

The exploration of new heterojunction materials is of great significance in reducing the cost of existing noble metal catalysts and thus realizing the large-scale application of electrocatalytic hydrolysis ***,a novel CoP/CoMoP_(2) heterojunction was synthesized and served as a hydrogen evolution reaction(HER)*** heterojunction has morphology of nanoporous structure,which is conducive to exposing more active sites and facilitating bubbles *** charge distribution is optimized by a strong interface interaction between CoP and CoMoP_(2).The catalyst’s conductivity and the adsorption properties of the intermediates have both been ***/CoMoP_(2) demonstrates excellent HER activity with an overpotential of 93.6 mV at 10 mA∙cm^(-2),which is competitive with the reported performance of analogous *** work provides insights into the development of innovative phosphide-based heterojunction electrocatalysts.

关键词： nanoporous CoP CoMoP_(2) heterojunction hydrogen evolution reaction

Melting geodynamics reveals 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 University 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 have abyssal-peridotite-like mineral compositions,including low Cr^(#)(20-3.)and TiO_(2) contents(3.(2.9wt%-4.4wt%)and CaO(1.9wt%-3.7wt%)contents in orthopyroxene and LREE-depletion in *** of these lherzolites can be modeled by~11%dynamic melting of the DMM source with a small fraction of melt(~0.5%)entrapped within the source,a similar melting process to typical abyssal *** Purang harzburgites are characterized by the porphyroclastic texture and exhibit highly refractory mineral compositions such as high spinel Cr^(#)(40-68),low orthopyroxene Al_(2)O_(3.(3.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 environment 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

A low-melting-point metal doping strategy for the synthesis of small-sized intermetallic Pt_(5)Ce fuel cell catalysts

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Nano Research 2024年第9期17卷 8112-8118页

作者： Zi-Jun Zou shi-Yi Yin Yao Tang Sheng-Liang zhong Lei Wang shi-Long Xu Hai-Wei Liang College of Chemistry and Chemical Engineering Jiangxi Normal UniversityNanchang 330022China Department of Chemistry University of Science and Technology of ChinaHefei 230026China School of Materials and Chemical Engineering Anhui Jianzhu UniversityHefei 230601China

Carbon-supported platinum-lanthanum(Pt-Ln)intermetallic compound(IMC)nanoparticles with high activity and robust stability have been demonstrated as promising cathode catalysts for proton-exchange membrane fuel ***,the preparation of Pt-Ln IMC catalysts needs high-temperature annealing treatment that inevitably causes nanoparticle sintering,resulting in significant reduction of the electrochemical surface area and mass-based ***,we prepare small-sized M-doped Pt_(5)Ce(M=Ga,Cd,and Sb)IMCs catalysts via a low-melting-point metal doping *** speculate that the doping of low-melting-point metals can facilitate the generation of vacancies in the crystal lattice through thermal activation and thus reduce the kinetic barriers for the formation of intermetallic Pt_(5)Ce *** prepared Ga-doped Pt_(5)Ce catalyst exhibits a higher electrochemical active surface area(81 m^(2)·gPt^(-1))and a larger mass activity(0.45 A·mgPt^(-1)at 0.9 V)over the undoped Pt_(5)Ce and commercial Pt/C *** the membrane electrode assembly test,the Ga-doped Pt_(5)Ce cathode delivers a power density of 0.98 W·cm^(-2)at 0.67 V,along with a voltage loss of only 27 mV at 0.8 A·cm^(-2)at the end of accelerated stability test.

关键词： P5Ce low-melting-point metal small-sized intermetallic compound catalysis fuel cells

Influences of shale microstructure on mechanical properties and bedding fractures distribution

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Petroleum Science 2024年第3期21卷 1944-1954页

作者： Ming-Zhe Gu Mao Sheng shi-zhong Cheng Fan-Hao Gong Gen-Sheng Li State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum-BeijingBeijing2249China College of Petroleum Engineering China University of Petroleum-BeijingBeijing102249China Shenyang Center of China Geological Survey ShenyangLiaoning110034China

The difference in microstructure leads to the diversity of shale mechanical properties and bedding fractures distribution *** this paper,the microstructure and mechanical properties of Longmaxi marine shale and Qingshankou continental shale were studied by X-ray diffractometer(XRD),field emission scanning electron microscope(FE-SEM)with mineral analysis system,and ***,the typical bedding layers area was properly stratified using Focused Ion Beam(FIB),and the effects of microstructure and mechanical properties on the distribution patterns of bedding fractures were *** results show that the Longmaxi marine shale sample contains more clay mineral grains,while the Qingshankou continental shale sample contains more hard brittle mineral grains such as *** Longmaxi marine shale sample,hard brittle minerals with grain sizes larger than 20μm is18.24%and those with grain sizes smaller than 20μm is 16.22%.For Qingshankou continental shale sample,hard brittle minerals with grain sizes larger than 20μm is 40.7%and those with grain sizes smaller than 20μm is 11.82%.In comparison to the Qingshankou continental shale sample,the Longmaxi marine shale sample has a lower modulus,hardness,and *** shales are formed by alternating coarse-grained and fine-grained layers during *** average single-layer thickness of Longmaxi marine shale sample is greater than Qingshankou continental shale *** two types of shale have similar bedding fractures distribution patterns and fractures tend to occur in the transition zone from coarse-grained to fine-grained *** orientation of the fracture is usually parallel to the bedding plane and detour occurs in the presence of hard brittle *** fracture distribution density of the Longmaxi marine shale sample is lower than that of the Qingshankou continental shale sample due to the strong heterogeneity of the Qingshankou continental *** current resea

关键词： Shale Nanoindentation Microstructure Mechanical property Fracture

Chiral multiple-resonance thermally activated delayed fluorescence materials based on chiral spiro-axis skeleton for efficient circularly polarized electroluminescence

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Science China Chemistry 2024年第7期67卷 2257-2264页

作者： shi-Quan Song Xiao Han zhong-zhong Huo Ching-Fai Yip Xian-Fang Hong Meng-Ning Ding You-Xuan Zheng State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China Key Laboratory of Mesoscopic Chemistry of Ministry of Education School of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China

Chiral luminescence materials have potential applications in the field of three-dimensional displays due to their circularly polarized luminescence(CPL)***,the further development of circularly polarized organic light-emitting diodes(CP-OLEDs)needs to meet the requirements of high efficiency,high color purity,low cost,and high dissymmetry factor(gPLor gEL),chiral multiple resonance thermally activated delayed fluorescence(MR-TADF)materials are considered as candidates in these ***,based on a pair of chiral spirofluorene precursors,two pairs of high-performance chiral MR-TADF emitters((R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB)are developed,which exhibit strong emissions peaking at 491 and 502 nm in toluene with full-width at half-maximum values of 25 and 3. nm,*** addition,small singlet–triplet energy gaps of 0.15 and 0.10 eV with high absolute photoluminescence efficiencies of 95.0%and 96.7%are observed for p-Spiro-DtBuCzB and m-Spiro-DtBuCzB molecules,*** based on p-Spiro-DtBuCzB and m-Spiro-DtBuCzB display high maximum external quantum efficiencies of 29.6%and 3..8%,*** importantly,CP-OLEDs present symmetric circularly polarized electroluminescence spectra with|gEL|factors of 3.3.×10^(-4)and 7.66×10^(-4)for devices based on(R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB enantiomers,respectively.

关键词： chiral spiro-axis skeleton-based material multiple resonance thermally activated delayed fluorescence circularly polarized electroluminescence dissymmetry factor external quantum efficiency