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Gas film/regenerative composite cooling characteristics of the liquid oxygen/liquid methane (LOX/LCH4) rocket engine

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第8期25卷 631-649页

作者： Xinlin LIU jun SUN Zhuohang JIANG Qinglian LI Peng CHENG jie SONG Science and Technology on Scramjet Laboratory College of Aerospace Science and EngineeringNational University of Defense TechnologyChangsha 410073China

The thermal protection of rocket engines is a crucial aspect of rocket engine *** this paper,the gas film/regenerative composite cooling of the liquid oxygen/liquid methane(LOX/LCH4)rocket engine thrust chamber was investigated.A gas film/regenerative composite cooling model was developed based on the Grisson gas film cooling efficiency formula and the one-dimensional regenerative cooling *** accuracy of the model was validated through experiments conducted on a 6 kg/s level gas film/regenerative composite cooling thrust ***,key parameters related to heat transfer performance were *** results demonstrate that the model is sufficiently accurate to be used as a preliminary design *** temperature rise error of the coolant,when compared with the experimental results,was found to be less than 10%.Although the pressure drop error is relatively large,the calculated results still provide valuable guidance for heat transfer *** addition,the performance of composite cooling is observed to be superior to regenerative *** the gas film flow rate results in higher cooling efficiency and a lower gas-side wall ***,the position at which the gas film is introduced greatly impacts the cooling *** optimal introduction position for the gas film is determined when the film is introduced from a single row of *** optimal introduction position results in a more uniform wall temperature distribution and reduces the peak ***,it is observed that a double row of holes,when compared to a single row of holes,enhances the cooling effect in the superposition area of the gas film and further lowers the gas-side wall *** results provide a basis for the design of gas film/regenerative composite cooling systems.

关键词： Liquid oxygen/liquid methane(LOX/LCH4)rocket engine Gas film cooling Regenerative cooling Heat transfer characteristics

Spray pyrolysis-derived W-doped MoSe_(2)/rGO paper-like microspheres:optimization of microstructure and mesostructure for enhanced lithium storage

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Rare Metals 2024年第7期43卷 3019-3031页

作者： Wei Wang jun-Yu Chen jie Ouyang Hong Yin Ao-jie Li Liang Chen jun-Lin Huang Yu-Can Zhu Gang-Yong Li Zhao-Hui Hou Key Laboratory of Hunan Province for Advanced Carbon-based Functional Materials Hunan Institute of Science and TechnologyYueyang 414006China School of Chemistry and Chemical Engineering Hunan Institute of Science and TechnologyYueyang414006China Hunan Province Key Laboratory of Materials Surface&Interface Science and Technology Material Science and Engineering SchoolCentral South University of Forestry and TechnologyChangsha 410004China International Iberian Nanotechnology Laboratory(INL) AvMestre Jose Veiga4715-330 BragaPortuga

Two-dimensional MoSe_(2) is a promising candidate for lithium-ion battery ***,its conductivity and lithium storage volumetric effect still need to be *** this work,W-doped MoSe_(2)/rGO paper-like microspheres are successfully prepared through ultrasonic spray pyrolysis,achieving optimization at both the microstructure and mesostructure to enhance the lithium storage performance of the ***,by utilizing the similar two-dimensional structure between MoSe_(2) and rGO,self-assembly is achieved through spray pyrolysis,resulting in a well-defined van der Waals heterostructure at the interface on the microscale,enhancing the electron and ion transfer capability of the ***,the mesoscale paper-like microsphere morphology provides additional volume expansion buffering ***,W-doping not only increases the interlayer spacing of MoSe_(2)(0.73 nm),thereby reducing the diffusion resistance of Li+,but also allow for the modulation of the energy band structure of the *** functional theory(DFT)calculations confirm that W-doped MoSe_(2)/rGO exhibits the narrowest bandgap(0.892 eV).Therefore,the composite demonstrates excellent lithium storage performance,maintaining a specific capacity of 732.9 mAh·g^(-1)after 300 cycles at a current density of 1 A·g^(-1).

关键词： Molybdenum selenide Heterostructure Microspheres Li-ion batteries Kinetics

A novel small-animal locomotor activity recording device for biological clock research

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Animal Models and Experimental Medicine 2024年第1期7卷 71-76页

作者： Yi-Long Wu Ming Zhong jun Yin Wei-jie Ou Yu-Bin Zhuang Nan-Wen Zhang Su Lin yue-Yong Zhu Endoscopy Center The First Affiliated HospitalFujian Medical UniversityFuzhouChina Department of Endocrinology The First Affiliated HospitalFujian Medical UniversityFuzhouChina Chuangke Workshop Technology Co. LtdShenzhenChina Department of Digestive Nutrition Fujian Children's HospitalFuzhouChina Experimental Animal Center Fujian Medical UniversityFuzhouChina Department of Pharmacology Fujian Medical UniversityFuzhouChina Department of Hepatology Hepatology Research InstituteClinical Research Center for Liver and Intestinal Diseases of Fujian ProvinceThe First Affiliated HospitalFujian Medical UniversityFuzhouChina

The rodent running-wheel recording apparatus is a reliable approach for studying cir-cadian *** study demonstrated how to construct a simple and intelligent running-wheel recording *** running wheel was attached to the cage's base,whereas the Hall sensor was attached to the cage's ***,the RJ25 adaptor relayed the running signal to the main control ***,the main control board was connected to the USB port of the computer with the USB *** were collected using the online-accessible,self-created software *** Magturning,generated data were saved and exported in real ***,the device was validated by collecting data on the locomotor activities of mice under dif-ferent light *** conclusion,this new device can record circadian activity of *** device is appropriate for interdisciplinary investigations related to biological clock research.

关键词： biological clock circadian rhythm intelligent equipment locomotor activity running wheel

High-density lipoprotein regulates angiogenesis by affecting autophagy via miRNA-181a-5p

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Science China(Life Sciences) 2024年第2期67卷 286-300页

作者： Bi-Ang Kang Hua-Ming Li Ya-Ting Chen Meng-jie Deng Yan Li yue-Ming Peng Jian-jun Gao Zhi-Wei Mo Jia-Guo Zhou Zhi-jun Ou Jing-Song Ou Division of Cardiac Surgery Cardiovascular Diseases InstituteThe First Affiliated HospitalSun Yat-sen UniversityGuangzhou 510080China National-Guangdong Joint Engineering Laboratory for Diagnosis and Treatment of Vascular Diseases Guangzhou 510080China NHC key Laboratory of Assisted Circulation(Sun Yat-sen University) Guangzhou 510080China Guangdong Provincial Engineering and Technology Center for Diagnosis and Treatment of Vascular Diseases Guangzhou 510080China Division of Vascular Surgery The First Affiliated HospitalSun Yat-sen UniversityGuangzhou 510080China Department of Pharmacology Cardiac and Cerebral Vascular Research CenterZhongshan School of MedicineSun Yat-sen UniversityGuangzhou 510080China Division of Hypertension and Vascular Diseases Department of CardiologyCardiovascular Diseases InstituteThe First Affiliated HospitalSun Yat-sen UniversityGuangzhou 510080China Guangdong Provincial Key Laboratory of Brain Function and Disease Zhongshan School of MedicineSun Yat-sen UniversityGuangzhou 510080China

We previously demonstrated that normal high-density lipoprotein(nHDL)can promote angiogenesis,whereas HDL from patients with coronary artery disease(d HDL)is dysfunctional and impairs *** plays a critical role in angiogenesis,and HDL regulates ***,it is unclear whether n HDL and d HDL regulate angiogenesis by affecting *** cells(ECs)were treated with n HDL and d HDL with or without an autophagy ***,endothelial nitric oxide synthase(e NOS)expression,miRNA expression,nitric oxide(NO)production,superoxide anion(O2^(·-))generation,EC migration,and tube formation were evaluated.n HDL suppressed the expression of miR-181a-5p,which promotes autophagy and the expression of e NOS,resulting in NO production and the inhibition of O2^(·-)generation,and ultimately increasing in EC migration and tube formation.d HDL showed opposite effects compared to n HDL and ultimately inhibited EC migration and tube *** found that autophagy-related protein 5(ATG5)was a direct target of ***5 silencing or miR-181a-5p mimic inhibited n HDL-induced autophagy,e NOS expression,NO production,EC migration,tube formation,and enhanced O2^(·-)generation,whereas overexpression of ATG5 or miR-181a-5p inhibitor reversed the above effects of d ***5 expression and angiogenesis were decreased in the ischemic lower limbs of hypercholesterolemic low-density lipoprotein receptor null(LDLr^(-/-))mice when compared to C57BL/6 ***5 overexpression improved angiogenesis in ischemic hypercholesterolemic LDLr^(-/-)*** together,nHDL was able to stimulate autophagy by suppressing miR-181a-5p,subsequently increasing e NOS expression,which generated NO and promoted *** contrast,d HDL inhibited angiogenesis,at least partially,by increasing miR-181a-5p expression,which decreased autophagy and e NOS expression,resulting in a decrease in NO production and an increase in O2^(·-)*** findings reveal a nov

关键词： high-density lipoprotein angiogenesis autophagy ATG5 miRNA endothelial nitric oxide synthase

Mechanical properties and microstructure of Mg-treated and Catreated industrial H13 steel after quenching and tempering

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Journal of Iron and Steel Research International 2024年第8期31卷 1987-2001页

作者： jun-ying yue Dong Hou De-yong Wang Tian-peng Qu Xiang-long Li jun Tian School of Iron and Steel Soochow UniversitySuzhou 215021JiangsuChina

The effect of magnesium treatment and calcium treatment on the microstructure and mechanical properties of industrial H13 steel after quenching and tempering was *** impact toughness and tensile tests were mainly carried out,and the microstructure was observed by scanning electron microscopy,electron backscattered diffraction,and X-ray *** results show that magnesium treatment is still feasible in industrial *** is mainly manifested in the refinement of lath martensite and *** with calcium treatment,the prior austenite grains and carbides size of industrial H13 steel treated with magnesium decreased by 3.17μm after *** quenching and tempering,the carbides(especially V-rich carbides)in Mg treatment obviously spheroidized and distributed uniformly and increased in quantity *** lath martensite size is reduced from 2.45 to 2.31μ*** suggests that magnesium treatment was able to yield smaller grains and more evenly distributed ***,the impact toughness,yield strength,and ultimate tensile strength of industrial H13 steel with magnesium treatment increased by 28%,65.5 MPa and 123.7 MPa,*** increment of strength mainly comes from dislocation strengthening,grain refinement strengthening,and precipitation strengthening,among which precipitation strengthening accounts for the largest proportion.

关键词： Industrial H13 steel Mg treatment Heat treatment Carbide-Mechanical property

Prediction for permeability index of blast furnace based on VMD-PSO-BP model

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Journal of Iron and Steel Research International 2024年第3期31卷 573-583页

作者： Xiao-jie Liu Yu-jie Zhang Xin Li Zhi-feng Zhang Hong-yang Li Ran Liu Shu-jun Chen School of Metallurgy and Energy North China University of Science and TechnologyTangshan 063210HebeiChina Chengde Branch HBIS Group Co.Ltd.Chengde 067000HebeiChina

The permeability index is one of the important production indicators to monitor the operation of blast *** is crucial to grasp the trends of changes in the new permeability index in *** the complex vibration spectrum of the permeability index,a prediction model of the permeability index based on the VMD-PSO-BP(variational mode decomposition-particle swarm optimization-back propagation)method was ***,the key factors that affect the permeability index of blast furnace were studied from multiple ***,the permeability index was divided into multiple sub-modes based on the difference of frequency bands by the VMD algorithm,and a PSO-BP prediction model was established for each ***,the prediction results of each sub-mode were summed to obtain the final *** results show that the composite prediction accuracy by using the VMD algorithm is 3%higher than that of the traditional prediction method,which has better applicability.

关键词： Big data-Blast furnace Air permeability Variational mode decomposition Particle swarm optimization Back propagation Model prediction

Relative difficulty distillation for semantic segmentation

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Science China(Information Sciences) 2024年第09期67卷 126-145页

作者： Dong LIANG yue SUN Yun DU Songcan CHEN Sheng-jun HUANG MIIT Key Laboratory of Pattern Analysis and Machine Intelligence College of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Shenzhen Research Institute Nanjing University of Aeronautics and Astronautics

Current knowledge distillation(KD) methods primarily focus on transferring various structured knowledge and designing corresponding optimization goals to encourage the student network to imitate the output of the teacher network. However, introducing too many additional optimization objectives may lead to unstable training, such as gradient conflicts. Moreover, these methods ignored the guidelines of relative learning difficulty between the teacher and student networks. Inspired by human cognitive science, in this paper, we redefine knowledge from a new perspective — the student and teacher networks' relative difficulty of samples, and propose a pixel-level KD paradigm for semantic segmentation named relative difficulty distillation(RDD). We propose a two-stage RDD framework: teacher-full evaluated RDD(TFE-RDD) and teacher-student evaluated RDD(TSE-RDD). RDD allows the teacher network to provide effective guidance on learning focus without additional optimization goals, thus avoiding adjusting learning weights for multiple losses. Extensive experimental evaluations using a general distillation loss function on popular datasets such as Cityscapes, Cam Vid, Pascal VOC, and ADE20k demonstrate the effectiveness of RDD against state-ofthe-art KD methods. Additionally, our research showcases that RDD can integrate with existing KD methods to improve their upper performance bound. Codes are available at https://***/sunyueue/***.

关键词： knowledge distillation semantic segmentation relative difficulty sample weighting prediction discrepancy

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How interfacial electron-donating defects influence the structure and charge of gold nanoparticles on TiO_(2)support

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Nano Research 2024年第7期17卷 5965-5974页

作者： Guang-jie Xia Yu Fu Wei Cao jun Li Yang-Gang Wang Department of Chemistry and Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and TechnologyShenzhen 518055China School of Physical Sciences Great Bay UniversityDongguan 523000China Department of Chemistry Tsinghua UniversityBeijing 100084China

The reduction degree of TiO_(2)support is critical to the performances of metal *** many previous theoretical calculations,only the bridge oxygen vacancy(Ov)was considered as the electron-donating defect on reduced rutile TiO_(2)(r-TiO_(2−x))***,titanium adatoms(Tiad.),oxidized titanium islands(***),and acid hydroxyls(ObrH)also exist at the metal/support *** conducting density functional theory(DFT)calculations and ab initio molecular dynamics(AIMD)simulations,we compared r-TiO_(2−x)surfaces with Ov,Tiad.,***,and ObrH sites loaded with Au nanoparticles(NPs).The results showed the Au NPs were oxygen-phobic but titanium-philic,resulting in wetting of Ov and *** short contact with *** and *** Bader charges of Au NPs(QM)showed a good linear relationship with the ideal number of donating electrons(Ne)from the defective sites(QM=−KeNe+QM,S),demonstrating the intrinsic electron allocation at the *** Ov,Tiad.,and *** exhibited similar slopes(Ke),relatively steeper than that of *** means in the scope of Au NP charge state,the *** *** have a close electron-donating ability with Ov,but the ObrH donates relatively fewer *** linear relationship can be extended approximately to other *** higher the metal work function,the steeper the Ke for easier electron donation from defective *** stronger the metal oxygen affinity,the more positive the intercept(QM,S).That explains the easy generation of metallic or negative Pt and Au NPs on r-TiO_(2−x),but hard for Cu and Zn in *** provides theoretical guidance for regulating the charge of metal NPs over TiO_(2−x)supports.

关键词： metal-support interaction titanium oxide oxygen vacancy surface hydroxyl titanium adatom

SciCN:A Scientific Dataset for Chinese Named Entity Recognition

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Computers, Materials & Continua 2024年第3期78卷 4303-4315页

作者： Jing Yang Bin Ji Shasha Li jun Ma jie Yu College of Computer National University of Defense TechnologyChangsha410073China

Named entity recognition(NER)is a fundamental task of information extraction(IE),and it has attracted considerable research attention in recent *** abundant annotated English NER datasets have significantly promoted the NER research in the English *** contrast,much fewer efforts are made to the Chinese NER research,especially in the scientific domain,due to the scarcity of Chinese NER *** alleviate this problem,we present aChinese scientificNER dataset–SciCN,which contains entity annotations of titles and abstracts derived from 3,500 scientific *** manually annotate a total of 62,059 entities,and these entities are classified into six *** to English scientific NER datasets,SciCN has a larger scale and is more diverse,for it not only contains more paper abstracts but these abstracts are derived from more research *** investigate the properties of SciCN and provide baselines for future research,we adapt a number of previous state-of-theart Chinese NER models to evaluate *** results show that SciCN is more challenging than other Chinese NER *** addition,previous studies have proven the effectiveness of using lexicons to enhance Chinese NER *** by this fact,we provide a scientific domain-specific *** results demonstrate that our lexicon delivers better performance gains than lexicons of other *** hope that the SciCN dataset and the lexicon will enable us to benchmark the NER task regarding the Chinese scientific domain and make progress for future *** dataset and lexicon are available at:https://***/yangjingla/***.

关键词： Named entity recognition dataset scientific information extraction lexicon