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Frequency Domain Fatigue Evaluation on SCR Girth-Weld Based on Structural Stress

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China Ocean Engineering 2024年第2期38卷 255-270页

作者： zhang long ZHAO tian-feng College of Safety and Ocean Engineering China University of Petroleum(Beijing)Beijing 102249China

The Steel Catenary Riser(SCR)is a vital component for transporting oil and gas from the seabed to the floating *** harsh environmental conditions and complex platform motion make the SCR’s girth-weld prone to fatigue *** structural stress fatigue theory and Master S-N curve method provide accurate predictions for the fatigue damage on the welded joints,which demonstrate significant potential and compatibility in multi-axial and random fatigue ***,we propose a new frequency fatigue model subjected to welded joints of SCR under multiaxial stress,which fully integrates the mesh-insensitive structural stress and frequency domain random process and transforms the conventional welding fatigue technique of SCR into a spectrum analysis technique utilizing structural ***,a full-scale FE model of SCR with welds is established to obtain the modal structural stress of the girth weld and the frequency response function(FRF)of modal coordinate,and a biaxial fatigue evaluation about the girth weld of the SCR can be achieved by taking the effects of multi-load correlation and pipe-soil interaction into *** research results indicate that the frequency-domain fatigue results are aligned with the time-domain results,meeting the fatigue evaluation requirements of the SCR.

关键词： SCR girth weld random vibration self(cross)power spectrum structural stress method biaxial fatigue damage

Advances of machining techniques for gradient structures in multi-principal-element alloys

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Rare Metals 2022年第12期41卷 4015-4026页

作者： Bo Li Chun-Ming Niu tian-long zhang Gong-Yu Chen Gang zhang Dong Wang Xiao-Ye Zhou Jia-Ming Zhu School of Civil Engineering Shandong UniversityJinan 250061China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Department of Materials Science and Engineering College of Science and EngineeringHong Kong Institute for Advanced StudyCity University of Hong KongHong Kong 999077China School of Physics and Optoelectronics Technology Baoji University of Arts and SciencesBaoji 721016China Center of Microstructure Science Frontier Institute of Science and TechnologyXi'an Jiaotong UniversityXi’an 710049China Guangdong Province Key Laboratory of Durability for Marine Civil Engineering School of Civil and Transportation EngineeringShenzhen UniversityShenzhen 518060China

Multi-principal-element alloys(MPEAs)are attracting increasing attentions because of their high strength and ductility,high fracture toughness,excellent corrosion resistance,outstanding thermal-softening resistance and high oxidation ***,gradient structures(GSs)have been shown to be effective in alleviating the strength-ductility trade-off although strength and ductility are mutually exclusive properties for metals,which provides an opportunity for developing highperformance ***,we summarized four processing methods for creating GSs in MPEAs,including rotationally accelerated shot peening(RASP),ultra-precision machining technology(UPMT),cyclic dynamic torsion(CDT),and ultrasonic surface rolling processing(USRP).Principles,advantages,disadvantages,and typical applications of these methods are discussed in this work.

关键词： Gradient structures(GSs) Multi-principalelement alloys(MPEAs) Strength-ductility trade-off Advanced processing technology

Human umbilical cord mesenchymal stem cells derivedexosomes on VEGF-A in hypoxic-induced mice retinal astrocytes and mice model of retinopathy of prematurity

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International Journal of Ophthalmology(English edition) 2024年第7期17卷 1238-1247页

作者： Xiao-tian zhang Bo-Wen Zhao Yuan-long zhang Song Chen tianjin Eye Hospital Tianjin 300020China tianjin Key Lab of Ophthalmology and Visual Science Tianjin 300020China

AIM:To observe the effect of human umbilical cord mesenchymal stem cells(hUCMSCs)secretions on the relevant factors in mouse retinal astrocytes,and to investigate the effect of hUCMSCs on the expression of vascular endothelial growth factor-A(VEGF-A)and to observe the therapeutic effect on the mouse model of retinopathy of prematurity(ROP).METHODS:Cultured hUCMSCs and extracted exosomes from them and then retinal astrocytes were divided into control group and hypoxia *** assay,flow cytometry,reverse transcription-polymerase chain reaction(RT-PCR)and Western blot were used to detect related *** mechanisms by which hUCMSCs exosomes affect VEGF-A expression in hypoxia-induced mouse retinal astrocytes were *** last,the efficacy of exosomes of UCMSCs in a mouse ROP model was ***6 was used to comprehensively process data ***:The secretion was successfully extracted from the culture supernatant of hUCMSCs by gradient *** oxygen species(ROS)and hypoxia inducible factor-1α(HIF-1α)of mice retinal astrocytes under different hypoxia time and the expression level of VEGF-A protein and VEGF-A mRNA increased,and the ROP cell model was established after 6h of *** secretions of medium and high concentrations of hUCMSCs can reduce ROS and HIF-1α,the expression levels of VEGF-A protein and VEGF-A mRNA are statistically significant and concentration *** with the ROP cell model group,the expression of phosphatidylinositol 3-kinase(PI3K)/protein kinase B(AKT)/mammalian target of rapamycin(mTOR)signal pathway related factors in the hUCMSCs exocrine group is significantly *** intravitreal injection of the secretions of medium and high concentrations of hUCMSCs can reduce VEGF-A and HIF-1αin ROP model *** staining shows that the number of retinal neovascularization in ROP mice decreases with the increase of the dose of hUCMSCs ***:In a hypoxia induced

关键词： human umbilical cord mesenchymal stem cells retinal astrocytes retinopathy of prematurity vascular endothelial growth factor hypoxia inducible factor

Research on the slagging characteristics of blended coals in a pilot-scale furnace

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2015年第3期16卷 204-216页

作者： Hao ZHOU Le-tian LI Hai-long zhang Bin ZHOU Institute for Thermal Power Engineering Zhejiang University Hangzhou 310027 China

This paper applies digital image techniques to observe the slagging characteristics of blended coals in a pilot-scale furnace. Collected deposit samples were analyzed by scanning electron microscopy linked with energy-dispersive X-ray analysis （SEM-EDX）, X-ray diffraction （XRD）, and X-ray Fluorescence （XRF） to acquire the microstructure, chemical composition, and mineralogy. The deposit thickness of three blends was analyzed between their parent coal A （Datong） and coal B （Shan）, and we noted that the time to reach a stable stage decreased with the ratio of coal B. The addition of coal A into coal B could remarkably restrained the growth and thickness of ash deposits. The results of XRD analysis indicated the initial layer was predominantly comprised of the crystalline minerals quartz, anorthite, or albite except for coal B. All of the blends and coals contained quartz and Ca- to Al-silicates （Ca0.68Na0.32）（All.68Si0.32）Si2O8 in the slag layer where iron-bearing minerals （e.g., ilvaite） were altered into an amorphous phase. The result of SEM-EDX suggested that there was an elemental disparity between the coal ash and deposit.

关键词： Blended coal Ash deposit Slagging Charge-coupled device (CCD) camera Mineralogy

Insights into in-situ imbibition behavior of fracturing fluid in propped shale fractures based on nuclear magnetic resonance:A case study from longmaxi Formation shale,Sichuan Basin,China

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Petroleum Science 2024年第1期21卷 410-429页

作者： Jing-Jing Guo Kai-Xiang Di Lie-Hui zhang Yu-long Zhao Hui-Ying Tang Rui-Han zhang Ye tian National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500SichuanChina

Shale gas is an important component of unconventional oil and gas *** the imbibition behavior is helpful to optimize flowback parameters and enhance gas *** imbibition studies have focused on shale matrix,and the pressure conditions discussed were mostly *** initial imbibition behavior begins from propped fractures to matrix,but there are few studies working on explaining the imbibition behavior in propped fractures or the phenomenon of many shale wells exhibit higher productivity after a“soaking”***,propped fracture samples were designed for imbibition and migration *** order to accurately study the mechanism and main influencing factors of fracturing fluid imbibition and migration in propped and unpropped shale fractures under high temperature and high pressure,a series of experiments based on nuclear magnetic resonance(NMR)were carried *** showed that NMR T_(2) spectra of all samples exhibited a bimodal *** final imbibition volume of fracturing fluid was positively related to pressure and fracture *** imbibition effect of fracturing fluid was more evident in matrix pores under high *** the migration during soaking stage,the fracturing fluid gradually migrated from large pores to small pores and gradually displaced the shale gas from the matrix,thus allowing the water blocking in propped fractures to self-unlock to some *** permeability decreased in the imbibition stage,while it recovered in the migration stage to some extent.

关键词： Forced imbibition Migration Soaking NMR T_(2)spectra Propped fracture Permeability recovery

Robust adaptive radar beamforming based on iterative training sample selection using kurtosis of generalized inner product statistics

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Journal of Systems Engineering and Electronics 2024年第1期35卷 24-30页

作者： tian Jing zhang Wei School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China National Key Laboratory of Electromagnetic Space Security Chengdu 610036China

In engineering application,there is only one adaptive weights estimated by most of traditional early warning radars for adaptive interference suppression in a pulse reputation interval(PRI).Therefore,if the training samples used to calculate the weight vector does not contain the jamming,then the jamming cannot be removed by adaptive spatial *** the weight vector is constantly updated in the range dimension,the training data may contain target echo signals,resulting in signal cancellation *** cope with the situation that the training samples are contaminated by target signal,an iterative training sample selection method based on non-homogeneous detector(NHD)is proposed in this paper for updating the weight vector in entire range *** principle is presented,and the validity is proven by simulation results.

关键词： adaptive radar beamforming training sample selection non-homogeneous detector electronic jamming jamming suppression

Efficacy of Daoyin combined with lower limb robot as a comprehensive rehabilitation intervention for stroke patients: a randomized controlled trial

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Journal of Traditional Chinese Medicine 2024年第3期44卷 530-536页

作者： tian Haolin YANG Yuanbin zhang Hu ZHAO Wenjing ZHOU Jing tian Jingfeng HE long LI Xuechao SHEN Qinxuan SHUAI Mei Department of First Rehabilitation Wangjing Hospital of China Academy of Chinese Medical SciencesBeijing100102 Department of Rehabilitation Shunyi HospitalBeijing Traditional Chinese Medicine HospitalBeijing101300China School of Biological Science and Medical Engineering Beihang UniversityBeijing100191China

OBJECTIVE: To assess the effectiveness of a comprehensive rehabilitation approach combining Traditional Chinese Medicine Daoyin with lower limb robotics during the recovery phase of stroke ***: Stroke patients meeting the specified criteria were randomly assigned to one of four groups using a random number table: Control group, Daoyin group, lower limb robot group(LLR group), and Daoyin and lower limb robot group(DLLR group). Each group received distinct treatments based on conventional rehabilitation *** treatment duration spanned two weeks with two days of rest per week. Pre-and post-intervention assessments included various scales: Fugl-Meyer Assessment(FMA),Berg balance scale(BBS), Barthel index(BI), Fatigue Scale-14(FS-14), Pittsburgh sleep quality index(PSQI),Hamilton Anxiety Scale(HAMA), and Hamilton Depression Scale(HAMD).RESULTS: Statistically significant differences were observed in the lower limb function measured by FAM between the Control group(15 ± 5) and the DLLR group(18 ± 5)(P = 0.049). In the Barthel index, a statistically significant difference was noted between the Control group(54 ± 18) and the DLLR group(64 ± 11)(P = 0.041).Additionally, significant differences were found in the Berg balance scale between the Control group(21 ± 10)and the DLLR group(27 ± 8)(P = 0.024), as well as between the Control group(21 ± 10) and the LLR group(26 ± 10)(P = 0.048).CONCLUSION: The findings of this study suggest that the combined use of Daoyin and robotics not only enhances motor function in stroke patients but also has a positive impact on fatigue, sleep quality, and mood. This approach may offer a more effective rehabilitation strategy for stroke patients.

关键词： stroke rehabilitation Daoyin lower limb robot randomized controlled trial

Mechanism Exploration of Euphorbia fischeriana Steud. for Liver Cancer Based on Aspartic Acid Identification in Metabolomics

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Chinese Journal of Integrative Medicine 2024年第6期30卷 507-514页

作者： ZHAO Jing tian Xin-chen zhang Jia-qi HUANG Chen SUN Yan QIAO Sen JIANG Shu-long Clinical Medical Laboratory Center Jining First People’s HospitalJiningShandong Province272000China Cheeloo College of Medicine Shandong UniversityJinan250000China

Objective:To investigate the anti-liver cancer effects and aspartic acid(Asp)-related action mechanism of Euphorbia fischeriana Steud.(LD).Methods:The mice model of liver cancer was established by injection of H22 *** 5 days,mice were randomly divided into model group,sorafenib group(20 mg/kg),LD high-dose(LDH,1.36 g/kg) group,LD medium-dose(LDM,0.68 g/kg) group,and LD low-dose(LDL,0.34 g/kg)group,10 mice each *** were intragastrically administered to the mice once daily for 10 days,*** weight,tumor size and tumor weight were *** index was *** changes of liver cancer tissues were evaluated by hematoxylin and eosin staining and TUNEL *** chromatography-mass spectrometer was used to analyze different metabolites between the model and LDH ***:After LD treatment,tumor weight,tumor size and hepatic index were reduced compared with the model *** and karyorrhexis of tumor cells were ***,61 differential metabolites(18 up-regulated,43 down-regulated) were affirmed and 20 pathways of KEGG(P<0.05) were *** addition,Bel-7402,HepG2 and H22 cell viabilities were significantly increased after adding Asp into the *** then,the cell proliferation effect induced by Asp was ameliorated by ***:The anti-liver cancer efficacy of LD extract was validated in H22 mice model,and inhibition of Asp level might be the underlying mechanism.

关键词： liver cancer Euphorbia fischeriana Steud. aspartic acid metabolomics

Experimental Study on Wire Melting Control Ability of Twin-Body Plasma Arc

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 184-194页

作者： Ruiying zhang Fan Jiang long Xue School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China Beijing Academy of Safety Engineering and Technology Beijing 102617China College of Mechanical and Energy Engineering Beijing University of TechnologyBeijing 100124China

The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer,which is beneficial to shape and property control in wire arc additive *** this paper,with the wire feeding speed as a characteristic quantity,the wire melting control ability of twin-body plasma arc was studied by adjusting the current separation ratio(under the condition of a constant total current),the wire current/main current and the position of the wire in the arc axial *** results showed that under the premise that the total current remains unchanged(100 A),as the current separation ratio increased,the middle and minimum melting amounts increased approximately synchronously under the effect of anode effect power,the first melting mass range remained constant;the maximum melting amount increased twice as fast as the middle melting amount under the effect of the wire feeding speed,and the second melting mass range was *** the wire current increased,the anode effect power and the plasma arc power were both factors causing the increase in the wire melting amount;however,when the main current increased,the plasma arc power was the only factor causing the increase in the wire melting *** average wire melting increment caused by the anode effect power was approximately 2.7 times that caused by the plasma arc *** minimum melting amount was not affected by the wire-torch distance under any current separation ratio *** the current separation ratio increased and reached a threshold,the middle melting amount remained constant with increasing wire-torch *** the current separation ratio continued to increase and reached the next threshold,the maximum melting amount remained constant with the increasing wire-torch *** effect of the wire-torch distance on the wire melting amount reduced with the increase in the current separation *** this study,the decoupling mechanism and ability of this innovative

关键词： Twin-body plasma arc Melting control ability Melting amount Current separation ratio