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Numerical Investigation on Characteristics of Supercritical CO_(2)Heat Transfer in Vertical Circular Tubes with Circumferentially Half-Side Heating

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Journal of Thermal Science 2024年第5期33卷 1744-1756页

作者： ZHANG yan ZHANG Xinyi yan Chenshuai wu Wenhua GAO Erman School of Energy and Power Engineering Northeast Electric Power UniversityJilin 132012China

The design of heat exchangers in the advanced supercritical power conversion system cannot be separated from the study of heat transfer ***-side heating mode is often encountered for solar receiver and supercritical ***,the characteristics of supercritical CO_(2)(sCO_(2))convection heat transfer in vertical tubes with circumferentially half-side heating was numerically investigated through the SST k-ωturbulent model which matches well with the experimental ***,heat transfer between sCO_(2)upflow and downflow was *** to film boiling heat transfer at subcritical pressure,numerical results were processed according to the supercritical pseudo-phase transition hypothesis,with liquid-like phase in the tube core region and vapor-like film in the region near the heated tube *** structure of two layers was demarcated by pseudo-critical temperature T_(pc).Therefore,sCO_(2)heat transfer was assessed according to double thermal resistances caused by vapor-like film near the wall and core liquid-like *** findings suggest that wall temperature for upflow is higher than that for downflow,which is attributed to larger thermal resistance in the fluid domain for upflow than that for *** difference guarantees the excellent heat transfer performance for downflow than *** is also further concluded that the formation of vapor-like film near the wall due to pseudo-phase transition plays a key role in dominating wall temperature and inducing heat transfer deterioration in half-side heating *** present contribution is significant to the design of supercritical heat exchanger under half-side heating mode.

关键词： supercritical CO_(2) pseudo-phase transition half-side heating thermal resistance flow direction

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Review of data security within energy blockchain:A comprehensive analysis of storage,management,and utilization

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High-Confidence Computing 2024年第3期4卷 82-102页

作者： Yunhua He Zhihao Zhou yan Pan Fahui Chong Bin wu Ke xiao Hong Li School of Information Science and Technology North China University of TechnologyBeijing 100144China China Industrial Control Systems Cyber Emergency Response Team Beijing 100040China Key Laboratory in Blockchain and Data Security by Ministry of Industry and Information Technology Beijing 100040China Institute of Information Engineering Chinese Academy of Sciences Beijing 100195China

Energy systems are currently undergoing a transformation towards new paradigms characterized by decarbonization,decentralization,democratization,and *** this evolving context,energy blockchain,aiming to enhance efficiency,transparency,and security,emerges as an integrated technological solution designed to address the diverse challenges in this *** security is essential for the reliable and efficient functioning of energy *** pressing need to address challenges related to secure data storage,effective data management,and efficient data utilization is increasingly *** paper offers a comprehensive survey of academic discourse on energy blockchain data security over the past five years,adopting an all-encompassing perspective that spans data storage,management,and *** work systematically evaluates and contrasts the strengths and weaknesses of various research ***,this paper proposes an integrated hierarchical on-chain and off-chain security energy blockchain architecture,specifically designed to meet the complex security requirements of multi-blockchain business ***,this paper identifies key directions for future research,particularly in advancing the integration of storage,management,and utilization of energy blockchain data security.

关键词： Energy blockchain Data security Storage Management Utilization

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Methanol steam reforming for hydrogen production driven by an atomically precise Cu catalyst

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Green Energy & Environment 2024年第7期9卷 1079-1084页

作者： Weigang Hu Haoqi Liu Yuankun Zhang Jiawei Ji Guangjun Li xiao Cai Xu Liu Wen wu Xu Weiping Ding yan Zhu School of Chemistry and Chemical Engineering Nanjing University School of Physical Science and Technology Ningbo University

Plasmon-induced hot-electron transfer from metal nanostructures is being intensely pursed in current photocatalytic research,however it remains elusive whether molecular-like metal clusters with excitonic behavior can be used as light-harvesting materials in solar energy utilization such as photocatalytic methanol steam *** this work,we report an atomically precise Cu13cluster protected by dual ligands of thiolate and phosphine that can be viewed as the assembly of one top Cu atom and three *** Cu13H10（SR）3（PR’3）7(SR=2,4-dichlorobenzenethiol,PR’3=P（4-FC6H4）3) cluster can give rise to highly efficient light-driven activity for methanol steam reforming toward H2production.

关键词： Nanocluster Photocatalysis Methanol steam reforming Atomically precise Copper catalyst

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Optically levitated micro gyroscopes with an MHz rotational vaterite rotor

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Microsystems & Nanoengineering 2024年第3期10卷 219-227页

作者： Kai Zeng Xiangming Xu Yulie wu Xuezhong wu Dingbang xiao College of Intelligence Science and Technology National University of Defense TechnologyChangsha 410073China College of Information and Communication National University of Defense TechnologyWuhan 430000China Key Laboratory of Satellite Navigation Technology National University of Defense TechnologyChangsha 410073China

The field of levitated optomechanics has experienced significant advancements in manipulating the translational and rotational dynamics of optically levitated particles and exploring their sensing *** concept of using optically levitated particles as gyroscopes to measure angular motion has long been explored but has not yet been proven either theoretically or *** this study,we present the first rotor gyroscope based on optically levitated high-speed rotating *** gyroscope is composed of a micrometer-size ellipsoidal vaterite particle that is driven to rotate at MHz frequencies in a vacuum *** an external angular velocity is input,the optical axis deviates from its initial position,resulting in changes in the frequency and amplitude of the rotational *** analyzing these changes,the angular velocity of the input can be accurately detected,making it the smallest rotor gyroscope in the *** angular rate bias instability of the gyroscope is measured to be 0.08°/s and can be further improved to as low as 10^(−9)°/h theoretically by cooling the motion and increasing the angular moment of the levitated *** work opens a new application paradigm for levitated optomechanical systems and may pave the way for the development of quantum rotor gyroscopes.

关键词： particles rotational angular

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Influence of High-Density Bedding Plane Characteristics on Hydraulic Fracture Propagation in Shale Oil Reservoir

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 3051-3071页

作者： xiao yan Di Wang Haitao Yu State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Beijing102206China State Energy Center for Shale Oil Research and Development Beijing102206China Department of Geotechnical Engineering College of Civil Engineering Tongji UniversityShanghai200092China Petroleum Exploration and Production Research Institute SINOPECBeijing102206China Key Laboratory of Deep Earth Science and Engineering(Sichuan University) Ministry of EducationChengdu610065China

The existence of high-density bedding planes is a typical characteristic of shale oil *** the behavior of hydraulic fracturing in high-density laminated rocks is significant for promoting shale oil *** this study,a hydraulic fracturing model considering tensile failure and frictional slip of the bedding planes is established within the framework of the unified pipe-interface element method(UP-IEM).The model developed for simulating the interaction between the hydraulic fracture and the bedding plane is validated by comparison with experimental *** hydraulic fracturing patterns in sealed and unsealed bedding planes are ***,the effects of differential stress,bedding plane permeability,spacing,and the friction coefficient of the bedding plane are *** results showed that a single main fracture crossing the bedding planes is more likely to form in sealed bedding planes under high differential *** decrease in bedding plane permeability and the increase in the friction coefficient also promote the fracture propagating perpendicular to the bedding *** with high-density bedding planes has a poorer fracturing effect than that with low-density bedding planes,as the hydraulic fracture is prone to initiate and propagate along the bedding ***,higher injection pressure is needed to maintain fracture propagation along the *** increase in bedding density will lead to a smaller fracturing *** fluid seepage into the bedding planes slows shale *** is recommended that increasing the injection flow rate,selecting alternative fracturing fluids,and employing multi-well/multi-cluster fracturing may be efficient methods to improve energy production in shale oil reservoirs.

关键词： Hydraulic fracturing bedding planes shale unified pipe-interface element method

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Bioinspired zinc-mediated umpolung thiolation of alkyl electrophiles: reaction development, scope and mechanism

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Science China Chemistry 2024年第3期67卷 898-907页

作者： Yuenian Xu yan Zhang Yong Liu Wen-wu Sun Jie Huang Hui He Yingjie wu Wen Liu Shao-Fei Ni Xu-Qiong xiao Xinxin Shao College of Material Chemistry and Chemical EngineeringKey Laboratory of Organosilicon Chemistry and Material Technology of Ministry of EducationHangzhou Normal UniversityHangzhou 311121China School of Pharmaceutical Sciences South-Central Minzu UniversityWuhan 430074China Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guang-dong Province Shantou UniversityShantou 515063China

Zinc-promoted umpolung thiolation of alkyl electrophiles with masked sulfur transfer reagents in the absence of nickel or copper catalysis is described. This protocol proceeds via a SET process of Zn to electrophilic sulfur reagent followed by insertion of Zn into disulfide and nucleophilic thiolation, providing straightforward access to a wide range of alkyl sulfides with broad substrate scope. A neutral TMEDA-ligated four-coordinated zinc thiolate with tetrahedra geometry was synthesized, isolated and fully characterized by NMR, IR and X-ray analysis. More importantly, the chemical reactivity of this active intermediate has been investigated, enabling the construction of C-Se, C-Te, Sb-S and Bi-S bonds to prepare valuable sulfur-containing molecules and beyond.

关键词： umpolung thiolation C(sp^(3))-S bond formation masked sulfur reagents reductive coupling

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Correction to:Assembly-level analysis on temperature coefficient of reactivity in a graphite-moderated fuel salt reactor fueled with low-enriched uranium

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Nuclear Science and Techniques 2024年第2期35卷 234-235页

作者： xiao-xiao Li De-yang Cui Chun-yan Zou Jian-Hui wu Xiang-Zhou Cai Jin-Gen Chen Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China CAS Innovative Academy in TMSR Energy System Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China

Following publication of the original article,the authors observed that both Fig.5 and Fig.4 depict the same *** 5 was inaccurately referenced and *** correct Fig.5 is copied below:The original article has been updated.

关键词： fuel enriched reactivity

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Lipoprotein(a)and Benefit of PCSK9 Inhibition in Emergency Complex Higher-risk and Indicated Patients

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Current Medical Science 2023年第6期43卷 1206-1212页

作者： Zhi-li JIN Tao HE Li PENG xiao-yan wu Di FAN Ming CHEN Yong-zhen FAN Yuan-lin GUO Zhi-bing LU Hai-rong WANG Department of Cardiovascular Medicine Zhongnan Hospital of Wuhan UniversityWuhan430071China Institute of Myocardial Injury and Repair Wuhan UniversityWuhan430071China Cardio-Metabolic Medicine Center Fuwai HospitalChinese Academy of Medical Sciences&Peking Union Medical CollegeBeijing100037China

Objective There is a large population of patients classified as complex higher-risk and indicated patients(CHIPs)in China with a poor *** treatment of these patients is complex and challenging,especially when acute cardiac events occur,such as acute coronary syndrome(ACS)or heart *** and some mechanical circulatory support(MCS)therapeutic devices can provide stable hemodynamic support for CHIPs-percutaneous coronary intervention(PCI).LDL-C is an important pathogenic factor in atherosclerosis,and the target of blood lipid *** studies have revealed that lipoprotein(a)[Lp(a)],which is formed when a covalent bond between apolipoprotein(a)and apolipoprotein B-100 is made,produces an LDL-like *** particle is an independent risk factor for the development of atherosclerosis,and is closely correlated to stent thrombosis and ***,this requires active ***9 inhibitors have been used in lipid-lowering treatment,and preventing *** present study explores the efficacy of PCSK9 inhibitors in CHIPs-ACS,and the association between the change in Lp(a)and survival after 2 years of *** The present real-world,prospective control study enrolled 321 CHIPs-ACS who underwent emergency PCI from August 2019 to November 2020,and these patients were followed up for 2 *** patients were divided into two groups:PCSK9 group(n=161)given the combined PCSK9 inhibitor(140 mg of evolocumab every 2 weeks)and statins-based therapy,and SOC group(n=160)treated with statin-based lipid-lowering therapy ***,the change in lipid index was measured,and the cardiovascular(CV)event recurrence rate was evaluated after one month and 2 ***,the contribution of serum lipid parameters,especially the Lp(a)alteration,in patients with earlier initiation of the PCSK9 inhibitor to the CV outcome was *** The LDL-C level was significantly reduced in both groups:52.3%in the PCSK

关键词： PCSK9 inhibitor complex higher-risk and indicated patients lipoprotein(a)level low-density lipoprotein cholesterol level 2-year cardiovascular event rate

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Investigation of high rate mechanical flow followed by ignition for high-energy propellant under dynamic extrusion loading

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Defence Technology（防务技术） 2024年第2期32卷 336-347页

作者： Liying Dong yanqing wu Kun yang xiao Hou State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

Investigating the ignition response of nitrate ester plasticized polyether(NEPE) propellant under dynamic extrusion loading is of great significant at least for two cases. Firstly, it helps to understand the mechanism and conditions of unwanted ignition inside charged propellant under accident ***, evaluates the risk of a shell crevice in a solid rocket motor(SRM) under a falling or overturning scene. In the present study, an innovative visual crevice extrusion experiment is designed using a dropweight apparatus. The dynamic responses of NEPE propellant during extrusion loading, including compaction and compression, rapid shear flow into the crevice, stress concentration, and ignition reaction, have been firstly observed using a high-performance high-speed camera. The ignition reaction is observed in the triangular region of the NEPE propellant sample above the crevice when the drop weight velocity was 1.90 m/s. Based on the user material subroutine interface UMAT provided by finite element software LS-DYNA, a viscoelastic-plastic model and dual ignition criterion related to plastic shear dissipation are developed and applied to the local ignition response analysis under crevice extrusion conditions. The stress concentration occurs in the crevice location of the propellant sample, the shear stress is relatively large, the effective plastic work is relatively large, and the ignition reaction is easy to occur. When the sample thickness decreases from 5 mm to 2.5 mm, the shear stress increases from 22.3 MPa to 28.6 MPa, the critical value of effective plastic work required for ignition is shortened from 1280 μs to 730 μs, and the triangular area is easily triggering an ignition reaction. The propellant sample with a small thickness is more likely to stress concentration, resulting in large shear stress and effective work, triggering an ignition reaction.

关键词： NEPE propellant Crevice extrusion Shear flow Sample thickness Ignition reaction

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Global-local combined features to detect pain intensity from facial expression images with attention mechanism

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Journal of Electronic Science and Technology 2024年第3期22卷 80-93页

作者： Jiang wu Yi Shi Shun yan Hong-Mei yan yangtze Delta Region Institute(Huzhou) University of Electronic Science and Technology of ChinaHuzhou313001China MOE Key Laboratory for Neuroinformation School of Life Science and TechnologyUniversity of Electronic Science and Technology of ChinaChengdu611731China College of Engineering University of California at Santa BarbaraSanta Barbara93106USA

The estimation of pain intensity is critical for medical diagnosis and treatment of *** the development of image monitoring technology and artificial intelligence,automatic pain assessment based on facial expression and behavioral analysis shows a potential value in clinical *** paper reports a framework of convolutional neural network with global and local attention mechanism(GLA-CNN)for the effective detection of pain intensity at four-level thresholds using facial expression ***-CNN includes two modules,namely global attention network(GANet)and local attention network(LANet).LANet is responsible for extracting representative local patch features of faces,while GANet extracts whole facial features to compensate for the ignored correlative features between *** the end,the global correlational and local subtle features are fused for the final estimation of pain *** under the UNBC-McMaster Shoulder Pain database demonstrate that GLA-CNN outperforms other state-of-the-art ***,a visualization analysis is conducted to present the feature map of GLA-CNN,intuitively showing that it can extract not only local pain features but also global correlative facial *** study demonstrates that pain assessment based on facial expression is a non-invasive and feasible method,and can be employed as an auxiliary pain assessment tool in clinical practice.

关键词： Attention Convolutional neural network Facial expression Pain intensity

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