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Prediction of contact resistance of electrical contact wear using different machine learning algorithms

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Friction 2024年第6期12卷 1250-1271页

作者： Zhen-bing CAI chun-lin li Lei YOU Xu-dong CHEN li-ping HE Zhong-qing CAO Zhi-nan ZHANG Tribology Research Institute Southwest Jiaotong UniversityChengdu 610031China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China

H62 brass material is one of the important materials in the process of electrical energy transmission and signal transmission,and has excellent performance in all *** the wear behavior of electrical contact pairs is particularly complex when they are in service,we evaluated the effects of load,sliding velocity,displacement amplitude,current intensity,and surface roughness on the changes in contact *** learning(ML)algorithms were used to predict the electrical contact performance of different factors after wear to determine the correlation between different factors and contact *** forest(RF),support vector regression(SVR)and BP neural network(BPNN)algorithms were used to establish RF,SVR and BPNN models,respectively,and the experimental data were trained and *** was proved that BP neural network model could better predict the stable mean resistance of H62 brass alloy after *** analysis shows that the load and current have great influence on the predicted electrical contact *** wear behavior of electrical contacts is influenced by factors such as load,sliding speed,displacement amplitude,current intensity,and surface roughness during *** learning algorithms can predict the electrical contact performance after wear caused by these *** results indicate that an increase in load,current,and surface roughness leads to a decrease in stable mean resistance,while an increase in displacement amplitude and frequency results in an increase in stable mean resistance,leading to a decline in electrical contact *** reduce testing time and costs and quickly obtain the electrical contact performance of H62 brass alloy after wear caused by different factors,three algorithms(random forest(RF),support vector regression(SVR),and BP neural network(BPNN))were used to train and test experimental results,resulting in a machine learning model suitable for predicting the stable mean

关键词： electrical contact wear contact resistance machine learning(ML) neural network

Overview of ectopic pancreas

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World Journal of Gastrointestinal Surgery 2024年第2期16卷 284-288页

作者： Chang-Fei li Qiu-ru li Miao Bai Yuan-Shi Lv Yan Jiao Patient Service Center The Second Hospital of Jilin UniversityChangchun 130000Jilin ProvinceChina Department of Neurology The Second Hospital of Jilin UniversityChangchun 130000Jilin ProvinceChina Department of Fundus Disease The Second Hospital of Jilin UniversityChangchun 130000Jilin ProvinceChina Department of Thyroid Head and Neck Surgery Jilin Cancer HospitalChangchun 130000Jilin ProvinceChina Department of Hepatobiliary and Pancreatic Surgery General Surgery CenterThe First Hospital of Jilin UniversityChangchun 130021Jilin ProvinceChina

This editorial discusses the article written by Zheng et al that was published in the latest edition of the World Journal of Gastrointestinal *** primary focus is on the causes,location,diagnosis,histological classification,and therapy of ectopic *** pancreas refers to the presence of pancreatic tissue that is situated in a location outside its usual anatomical placement,and is not connected to the normal pancreas in terms of blood supply or anatomical ***,the embryological origin of ectopic pancreas remains *** most prevalent form of ectopic pancreatic is gastric ectopic *** ultrasonography examination can visualize the morphological charac-teristics of the ectopic pancreatic lesion and pinpoint its anatomical *** histological categorization of ectopic pancreas *** treatment has been widely advocated in ectopic pancreas.

关键词： Pancreas Gastric ectopic pancreas Diagnosis Treatment Anatomy

Hemichorea in patients with temporal lobe infarcts: Two case reports

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World Journal of Clinical Cases 2024年第4期12卷 806-813页

作者： Xu-Dong Wang Xing li chun-lian Pan Department of Neurology Puren Hospital Affiliated to Wuhan University of Science and TechnologyWuhan 430081Hubei ProvinceChina School of Medicine Wuhan University of Science and TechnologyWuhan 430065Hubei ProvinceChina

BACKGROUND Hemichorea and other hyperkinetic movement disorders are uncommon present-ations of stroke and are usually secondary to deep infarctions affecting the basal ganglia and ***,temporal ischemic lesions causing hemichorea are *** report the cases of two patients with acute ischemic temporal lobe infarct strokes that presented as *** SUMMARY Patient 1:An 82-year-old woman presented with a 1-mo history of involuntary movement of the left extremity,which was consistent with *** diffusion-weighted imaging(DWI)revealed an acute ischemic stroke that predominantly affected the right temporal cortex,and magnetic resonance angiography of the head showed significant stenosis of the right middle cerebral artery(MCA).Treatment with 2.5 mg of olanzapine per day was *** she was discharged from the hospital,her symptoms appeared to have improved compared with those previously ***-seven days after the first admission,she was readmitted due to acute ischemic *** tomogra-phy perfusion showed marked hypoperfusion in the right MCA *** emergency transfemoral cerebral angiogram was performed and showed severe stenosis in the M1 segment of the right *** percutaneous transluminal angioplasty was successfully performed,abnormal movements or other neuro-logic problems did not *** 2:A 76-year-old man was admitted to our hospital for a 7-d history of right-upper-sided involuntary *** showed an acute patchy ischemic stroke in the left temporal lobe without basal ganglia *** diffusion tensor imaging confirmed fewer white matter fiber tracts on the left side than on the opposite *** with 2.5 mg of olanzapine per day improved his condition,and he was *** When acute hemichorea suddenly appears,temporal cortical ischemic stroke should be considered a possible *** addition,hemichorea may be a sign of impending cerebral infarcti

关键词： Acute ischemic stroke Temporal ischemic stroke Movement disorders Cortical hemichorea Case report

Mechanical behaviors of mylonitic granite and granitic protomylonite in a deep ductile shear zone

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2663-2677页

作者： Lanbin Zhang ru Zhang li Ren Zhilong Zhang Zetian Zhang Dong Wang Xinzhong Wang Huijun Lu State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering College of Water Resource and HydropowerSichuan UniversityChengdu610065China MOE Key Laboratory of Deep Earth Science and Engineering Sichuan UniversityChengdu610065China China Railway Eryuan Engineering Group Company Ltd.Chengdu610065China School of Architecture and Civil Engineering Xihua UniversityChengdu610065China

For projects near the tectonic belt,mylonite of varying metamorphic degrees may be *** matrix proportion of rock reflects its internal microscopic characteristics,thus it is beneficial for engineering geology to study the effect of the matrix proportion on the mechanical properties and rupture behaviors of *** of mylonitic granite and granitic protomylonite with varying matrix proportions were obtained from a ductile shear zone for a series of uniaxial compression and acoustic emission(AE)*** results showed that with the increase in matrix proportion,the average strength and elastic modulus of the samples increased,and the rock sample with the largest matrix proportion exhibited the maximum peak stress of 244.42 MPa,which was 45.86%greater than the average peak stress of the rock samples with the smallest matrix *** the rock samples with larger matrix proportion,their mechanical parameters exhibited greater dispersion and the large-scale appearance of AE events occurred earlier,showing a relatively gradual failure *** samples had larger accumulated AE parameter values and greater degree of *** contrast,for samples with smaller matrix proportions,the large-scale appearance of AE events occurred close to the peak stress,indicating that the occurrence of damage and fractures was centralized and *** samples had lower accumulated AE parameter values and fewer cracks after ***,for the rock samples with more matrix proportion,the average variance of the b-value was 1.1,which was lower than that of rock samples with the smallest matrix proportion(the average variance of the b-value was 3.7).Furthermore,it can be predicted that under certain stress,the failure depth around a tunnel is generally smaller when the strength of rock samples with larger matrix proportion is greater.

关键词： Mylonite Matrix proportion Mechanical properties Acoustic emission(AE) rupture behaviors

Theoretical and experimental investigations on single-atom catalysis:Pt_(1)/FeO_(x) for water-gas shift reaction

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Nano Research 2024年第9期17卷 8627-8637页

作者： Shan-Fei Wang Yangyang li Haiyan Wang Jin-Xia liang chun Zhu Botao Qiao School of Chemistry and Chemical Engineering Guizhou UniversityGuiyang 550025China CAS Key Laboratory of Science and Technology on Applied Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100049China

Oxide-supported metal single-atom catalysts(SACs)have exhibited excellent catalytic performance for water-gas shift(WGS)***,we report the single-atom catalyst Pt1/FeOx exhibits excellent medium temperature catalytic performance for WGS reactions by the density functional theory(DFT)calculations and experimental *** calculations indicate that H_(2)O molecules are easily dissociated at oxygen vacancies,and the formed*OH and*O are adsorbed on Pt1 single atoms and the adjacent O atoms,*** studying four possible reaction mechanisms,it is found that the optimal WGS reaction pathway is proceeded along the carboxyl mechanism(pathway III),in which the formation of*COOH intermediates can promote the stability of Pt_(1)/FeO_(x) SAC and the easier occurrence of WGS *** energy barrier of the rate-determining step during the entire reaction cycle is only 1.16 eV,showing the high activity for the medium temperature WGS reaction on Pt_(1)/FeO_(x) SAC,which was verified by experimental ***,the calculated turnover frequencies(TOFs)of CO_(2)and H_(2)formation on Pt1/FeOx at 610 K(337℃)can reach up to 1.14×10^(-3)s^(-1)·site^(-1)through carboxyl *** this work,we further expand the application potential of Pt1/FeOx SAC in WGS reaction.

关键词： water-gas shift(WGS)reaction single-atom catalyst(SAC) density functional theory(DFT) thermocatalysis

Effect of Sonic hedgehog gene-modified bone marrow mesenchymal stem cells on graft-induced retinal gliosis and retinal ganglion cells survival in diabetic mice

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International Journal of Ophthalmology(English edition) 2024年第1期17卷 34-41页

作者： Tong Wang Hai-chun li Jin Ma Xi-ling Yu State Key Laboratory of Ophthalmology Zhongshan Ophthalmic CenterSun Yat-sen UniversityGuangdong Provincial Key Laboratory of Ophthalmology and Visual ScienceGuangzhou 510060Guangdong ProvinceChina

AIM:To investigate the effects of Sonic hedgehog(Shh)gene-modified bone marrow mesenchymal stem cells(MSCs)on graft-induced retinal gliosis and retinal ganglion cells(RGCs)survival in diabetic ***:Bone marrow-derived MSCs were genetically modified with the Shh gene to generate a stably transfected cell line of Shh-modified MSCs(MSC-Shh).Intravitreal injections of MSC-Shh and green fluorescent protein-modified MSCs(MSC-Gfp;control)were administered in diabetic *** 4wk,the effects of MSC-Shh on retinal gliosis were evaluated using fundus photography,and markers of gliosis were examined by immunofluorescence and Western *** neurotrophic factors expression and RGCs survival in the host retina were evaluated using Western blotting and *** mechanisms underlying the effects of MSC-Shh was ***:A significant reduction of proliferative vitreoretinopathy(PVR)was observed after intravitreal injection of MSC-Shh compared to *** downregulation of glial fibrillary acidic protein(GFAP)was demonstrated in the host retina after MSC-Shh administration compared to *** extracellular signal-regulated kinase 1/2(ERK1/2),protein kinase B(AKT)and phosphatidylin-ositol-3-kinase(PI3K)pathways were significantly downregulated after MSC-Shh administration compared to ***-derived neurotrophic factor(BDNF)and ciliary neurotrophic factor(CNTF)levels were significantly increased in the host retina,and RGCs loss was significantly prevented after MSC-Shh ***:MSC-Shh administration reduces graft-induced reactive gliosis following intravitreal injection in diabetic *** ERK1/2,AKT and PI3K pathways are involved in this ***-Shh also increases the levels of neurotrophic factors in the host retina and promoted RGCs survival in diabetic mice.

关键词： mesenchymal stem cells Sonic hedgehog signaling reactive gliosis diabetic retinopathy retinal ganglion cells

A compact X-band backward traveling-wave accelerating structure

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Nuclear Science and Techniques 2024年第5期35卷 13-29页

作者： Xian-Cai lin Hao Zha Jia-ru Shi Qiang Gao Fang-Jun Hu Qing-Zhu li Huai-Bi Chen Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China

Very high-energy electrons(VHEEs)are potential candidates for FLASH radiotherapy for deep-seated *** proposed a compact VHEE facility based on an X-band high-gradient high-power *** this study,we investigated and realized the first X-band backward traveling-wave(BTW)accelerating structure as the buncher for a VHEE facility.A method for calculating the parameters of single cell from the field distribution was introduced to simplify the design of the BTW ***-domain circuit equations were applied to calculate the transient beam parameters of the buncher in the unsteady state.A prototype of the BTW structure with a thermionic cathode-diode electron gun was designed,fabricated,and tested at high power at the Tsinghua X-band high-power test *** structure successfully operated with 5-MW microwave pulses from the pulse compressor and outputted electron bunches with an energy of 8 MeV and a pulsed current of 108 mA.

关键词： Backward traveling-wave accelerating structure Equivalent circuit model High-power test Very high-energy electron radiotherapy

Constructing highly safe and long-life calcium ion batteries based on hydratedvanadium oxide cathodes featuring a pillar structure

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Rare Metals 2024年第6期43卷 2597-2612页

作者： chun-Fang Wang Shi-Wei Zhang Lan Huang Yuan-Min Zhu Feng liu Jian-Chuan Wang li-Ming Tan chun-Yi Zhi Cui-Ping Han Powder Metallurgy Research Institute Central South UniversityChangsha410083China Songshan Lake Materials Laboratory Dongguan 523808China Research Institute of Interdisciplinary Science and School of Materials Science and Engineering Dongguan University of TechnologyDongguan 523808China Department of Materials Science and Engineering City University of Hong KongHong Kong 999077China Faculty of Materials Science and Energy Engineering/Institute of Technology for Carbon Neutrality Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

Calcium-ion batteries(CIBs)have generated intense interest due to the growing demand for safer,cheaper,and large-scale energy storage ***,their development is still in its infancy,owing to the lack of suitable cathodes for sustaining reversiblc Ca^(2+)intercalation/***,layered H_(2)V_(3)O_(8)(HVO)with Zn^(2+)pre-insertion(ZHVO)is reported as a high-rate and highly durable cathode material for *** existence of Zn^(2+)and H_(2)O pillars could expand the interlayer spacing up to 1.8 nm,which is favorable for the diffusion of bulky Ca^(2+).The formation of Zn-O bonds facilitates electron transfer and enhances electrical ***,the ZHVO cathode achieves superior capacity performance(213.9 mAh·g^(-1)at 0.2 A·g^(-1))and long lifespan(78.3%for 1,000 cycles at 5 A·g^(-1))compared to pristine *** functional theory(DFT)calculations revealed that Zn^(2+)moved during Ca^(2+)intercalation,thereby reducing the diffusion energy barrier and facilitating Ca^(2+)***,a safe aqueous calcium ion cell was successfully assembled.

关键词： Multivalent batteries Calcium-ion batteries Layered structure Vanadium oxide Cathode materials

Climate warming is likely to weaken the performance of two-phase closed thermosyphon on the Qinghai-Tibet Plateau

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Advances in Climate Change Research 2024年第1期15卷 90-100页

作者： Guan-li JIANG Zi-Teng FU Xin-Yu MEN Hong-Ting ZHAO Si-ru GAO Yong-Zhi li Qing-Bai WU State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Beiluhe Observation and Research Station on Frozen Soil Engineering and Environment in the Qinghai-Tibet Plateau Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Muli Field Scientific Observation and Research Station for Gas Hydrate China Geological SurveyBeijing 100083China University of Chinese Academy of Sciences Beijing 100049China School of Civil Engineering and Architecture Jiaxing Nanhu UniversityJiaxing 314001China

Over the years,numerous geotechnical approaches have been implemented to mitigate the adverse effects of climate warming on various infrastructures in the permafrost region of the Qinghai-Tibet Plateau(QTP),such as the Qinghai-Tibet Highway and Railway,and achieved the expected engineering ***,little attention has been given to whether the performance of these geotechnical approaches has changed during the ongoing process of climate *** investigate the performance variation of one of these geotechnical approaches,which is two-phase closed thermosyphon(TPCT),during sustained climate warming,we conducted a statistical analysis of soil temperature monitoring data in 2003-2020 from eight regular embankments and six TPCT embankments in our permafrost monitoring *** results indicate that TPCT undeniably has a cooling effect on the permafrost beneath embankments,even rapidly eliminated previously formed taliks beneath ***,further analysis reveals that the performance of TPCT has been weakening during sustained climate warming,which has confirmed by the re-forming of the taliks beneath embankment where they had been previously *** on the current understanding,we attributed the weakening of thermosyphon performance to a significant reduction in the air temperature freezing index caused by ongoing climate *** this study,we aimed to draw attention to the evolving performance of geotechnical approaches in permafrost regions amid climate warming,prompting necessary engineering innovations to address this situation and ensure the sustainable development of the permafrost region on the QTP.

关键词： Two-phase closed thermosyphon Climate warming Supra-permafrost talik Permafrost degradation Qinghai-Tibet Highway