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Study on the clogging mechanism of punching screen in sand control by the punching structure parameters

Petroleum Science 2024年第1期21卷 609-620页

作者： Fu-Cheng Deng Fu-Lin Gui Bai-Tao Fan Lei Wen Sheng-Hong Chen Ning Gong yun-Chen Xiao Zhi-Hui Xu Yangtze University Jingzhou434023HubeiChina CNOOC Research Institute Ltd. Beijing100028China CNOOC Ener Tech-Drilling&Production Co. Tianjin300457China Tianjin Branch of CNOOC Ltd. Tianjin300459China

As an independent sand control unit or a common protective shell of a high-quality screen,the punching screen is the outermost sand retaining unit of the sand control pipe which is used in geothermal well or oil and gas ***,most screens only consider the influence of the internal sand retaining medium parameters in the sand control performance design while ignoring the influence of the plugging of the punching screen on the overall sand retaining performance of the *** explore the clogging mechanism of the punching screen,this paper established the clogging mechanism calculation model of a single punching screen sand control unit by using the computational fluid mechanics-discrete element method(CFD-DEM)combined *** to the combined motion of particles and fluids,the influence of the internal flow state on particle motion and accumulation was *** results showed that(1)the clogging process of the punching sand control unit is divided into three stages:initial clogging,aggravation of clogging and stability of *** the initial stage of blockage,coarse particles form a loose bridge structure,and blockage often occurs preferentially at the streamline gathering place below chamfering inside the sand control *** the stage of blockage intensification,the particle mass develops into a relatively complete sand bridge,which develops from both ends of the opening to the center of the *** the stable plugging stage,the sand deposits show a“fan shape”and form a“V-shaped”gully inside the punching slot element.(2)Under a certain reservoir particle-size distribution,The slit length and opening height have a large influence on the permeability and blockage rate,while the slit width size has little influence on the permeability and blockage *** microscopic clogging mechanism and its law of the punching screen prevention unit are proposed in this study,which has some field guidance significance for the design of punching screen

关键词： Punching screen Plugging CFD-DEM Size parameter Sand control

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One dimensional pea-shaped NiSe_(2) nanoparticles encapsulated in N-doped graphitic carbon fibers to boost redox reversibility in sodium-ion batteries

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Journal of Materials Science & Technology 2024年第1期168卷 215-226页

作者： Hyunjeong Gim Achmad Yanuar Maulana Jiwon Choi Jungwook song Boram yun Yuri Jeong Nahyun An Myeongkee Park Cybelle M.Futalan Jongsik Kim Department of Chemical Engineering(BK21 FOUR Graduate Program) Dong-A UniversityBusan 49315Korea(the Republic of) Department of Chemistry Dong-A UniversityBusan 49315Korea(the Republic of) Department of Chemistry Pukyong National UniversityBusan 48513Korea(the Republic of) Institute of Civil Engineering University of the PhilippinesDiliman 1127Philippines

In recent years,sodium-ion batteries(SIBs)have emerged as a promising technology for energy storage systems(ESSs)because of the abundance and affordability of ***,metal selenides have been studied as promising high-performance conversion-type anode materials in *** them,nickel se-lenide(NiSe_(2))has received considerable attention due to its high theoretical capacity of 495 mAh g^(-1)and ***,it still suffers from poor cycling stability because of the low electrochemical reactivity,large volume expansion,and structural instability during *** address these challenges,NiSe_(2)nanoparticles encapsulated in N-doped graphitic carbon fibers(NiSe_(2)@NGCF)were synthesized by using ZIF-8 as a ***_(2)@NGCF showed a high discharge capacity of 558.3 mAh g^(-1)with a fading rate of 0.14%per cycle after 200 cycles at 0.5 A g^(-1)in 0.01-3.0 *** a very high current density of 5 A g^(-1),the capacity still displayed excellent long-term cycle life with a discharge capacity of 406.1 mAh g^(-1)with a fading rate of 0.016%per cycle after 3000 *** mechanism of the excellent electrochem-ical performance of NiSe_(2)@NGCF was thoroughly investigated by ex-situ XRD,TEM,and SEM ***,NiSe_(2)@NGCF//Na_(3)V_(2)(PO_(4))_(3)full-cell also delivered an excellent reversible capacity of 378.7 mAh g^(−1)at 0.1 A g^(−1)after 50 cycles,demonstrating its potential for practical application in SIBs.

关键词： sodium-ion batteries Anode materials Nickel selenide N-doped graphitic carbon fibers One-dimensional electrode

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Cyclic Pulsating Pressure Enhanced Segregating Structuration of Ultra-High Molecular Weight Polyethylene/Graphene Composites as High-performance Light-Weight EMI Shields

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Chinese Journal of Polymer Science 2024年第7期42卷 958-967,I0008页

作者： yun-Zhi Huang Xiao-Xiao Liu Lan-Wei Li Guang-Ming Huang Zhao-Xia Huang Jin-Ping Qu National Engineering Research Center of Novel Equipment for Polymer Processing Key Laboratory of Polymer Processing EngineeringMinistry of EducationGuangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced ManufacturingSchool of Mechanical and Automotive EngineeringSouth China University of TechnologyGuangzhou 510641China School of Advanced Manufacturing Technology Guangdong Mechanical&Electrical PolytechnicGuangzhou 510550China

Currently,the enhancement in electromagnetic interference(EMI)performance of polymeric composite generally relies on either improving electrical conductivity(σ)for stronger electromagnetic(EM)reflections or tailoring structure for higher EM ***,we proposed a novel technique called cyclic pulsating pressure enhanced segregating structuration(CPP-SS),which can reinforce these two factors *** structural information was supplied by optical microscopy(OM)and scanning electron microscopy(SEM),both of which confirmed the formation and evolution of segregate structured ultra-high molecular weight polyethylene(UHMWPE)/graphene ***,the result showed that CPP-SS can significantly improve theσof ***,advanced specific EMI shielding efficiency of 31.1 d B/mm was achieved for UHMWPE/graphene composite at 1-mm thickness and a low graphene loading of 5 wt%.Meanwhile,it also confirmed that the intrinsic disadvantage of poor mechanical properties of conventional segregated structure composites can be *** work is believed to provide a fundamental understanding of the structural and performance evolutions of segregated structured composites prepared under CPPSS,and to bring us a simple and efficient approach for fabricating high-performance,strong and light-weight polymeric EMI shields.

关键词： Cyclic pulsating pressure Segregated structure Ultra-high molecular weight polyethylene Graphene Electromagnetic interface

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Diagnostic Accuracy of Computerized Bowel sound Analysis with Non-Invasive Devices for Irritable Bowel Syndrome:A Systematic Review and Meta-Analysis

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Chinese Medical Sciences Journal 2024年第2期39卷 122-130页

作者： Xia-Xiao Yan Yue-Lun Zhang Yu-Pei Zhang Ying-yun Yang Dong Wu Department of Gastroenterology State Key Laboratory of Complex Severe and Rare DiseasesPeking Union Medical College HospitalChinese Academy of Medical Sciences&Peking Union Medical CollegeBeijing 100730China Eight-Year Medical Doctor Program Chinese Academy of Medical Sciences&Peking Union Medical CollegeBeijing 100730China Medical Research Center Peking Union Medical College HospitalChinese Academy of Medical Sciences&Peking Union Medical CollegeBeijing 100730China

Objective To assess the diagnostic accuracy of bowel sound analysis for irritable bowel syndrome(IBS)with a systematic review and *** We searched MEDLINE,Embase,the Cochrane Library,Web of Science,and IEEE Xplore databases until September ***-sectional and case-control studies on diagnostic accuracy of bowel sound analysis for IBS were *** estimated the pooled sensitivity,specificity,positive likelihood ratio,negative likeli-hood ratio,and diagnostic odds ratio with a 95% confidence interval(CI),and plotted a summary receiver operat-ing characteristic curve and evaluated the area under the *** Four studies were *** pooled diagnostic sensitivity,specificity,positive likelihood ratio,nega-tive likelihood ratio,and diagnostic odds ratio were 0.94(95%CI,0.87‒0.97),0.89(95%CI,0.81‒0.94),8.43(95%CI,4.81‒14.78),0.07(95%CI,0.03‒0.15),and 118.86(95%CI,44.18‒319.75),respectively,with an area under the curve of 0.97(95%CI,0.95‒0.98).Conclusions Computerized bowel sound analysis is a promising tool for ***,limited high-quality data make the results'validity and applicability *** is a need for more diagnostic test accuracy studies and better wearable devices for monitoring and analysis of IBS.

关键词： irritable bowel syndrome bowel sound analysis diagnostic accuracy systematic review meta-analysis

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A computed tomography-based radiomic model for the prediction of strangulation risk in patients with acute intestinal obstruction

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Intelligent Medicine 2024年第1期4卷 33-42页

作者： Zhibo Wang Ruiqing Liu Shunli Liu Baoying Sun Wentao Xie Dongsheng Wang yun Lu Department of Gastroenterological Surgery The Affiliated Hospital of Qingdao UniversityQingdaoShandong 266003China Department of Radiology The Affiliated Hospital of Qingdao UniversityQingdaoShandong 266003China Neurology Department Central Hospital Affiliated to Shandong First Medical UniversityJinanShandong 250000China Lingshui People’s Hospital LingshuiHainan 572400China

Background We created and validated a computed tomography(CT)-based radiomic model using both clinical factors and the radiomic signature for assessing the strangulation risk of acute intestinal *** would assist surgeons in accurately predicting intestinal ischemia and strangulation in patients with intestinal *** We recruited 289 patients with acute intestinal obstruction admitted in the Affiliated Hospital of Qingdao University from January 2019 to February *** patients were allocated to a training(n=226)and validation cohort(n=63).Radiomic features were collected from CT images,and the radiomic signature was extracted and used to calculate a radiomic score(Rad-score).A nomogram was constructed using the clinical features and the Rad-score,and the performance of the clinical,radiomics,and nomogram models was assessed in the two *** Six robust features were used to construct the radiomic *** nomogram incorporating hemoglobin levels,C-reactive protein levels,American society of Anesthesiologists score,time of obstruction,CT image of mesenteric fluid(P<0.05),and the signature demonstrated good predictive ability for intestinal ischemia in patients with acute intestinal obstruction,with areas under the curve of 0.892(95%confidence interval,0.837–0.947)and 0.781(95%confidence interval,0.619–0.944)for the training and validation sets,*** decision curve analysis showed that this model outperformed the clinical and radiomic signature *** The radiomic nomogram may effectively predict intestinal ischemia in patients with acute intestinal disease and may assist clinical decision-making。

关键词： Acute intestinal obstruction Radiomics Intestinal ischemia Intestinal strangulation

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A Novel Divide and Conquer solution for Long-term Video Salient Object Detection

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Machine Intelligence Research 2024年第4期21卷 684-703页

作者： yun-Xiao Li Cheng-Li-Zhao Chen Shuai Li Ai-Min Hao Hong Qin State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing 100191China College of Computer Science and Technology China University of Petroleum(East China)Qingdao 266580China Department of Computer Science Stony Brook UniversityNew York 11794USA

Recently,a new research trend in our video salient object detection(VsoD)research community has focused on enhancing the detection results via model self-fine-tuning using sparsely mined high-quality keyframes from the given *** such a learning scheme is generally effective,it has a critical limitation,i.e.,the model learned on sparse frames only possesses weak generalization *** situation could become worse on“long”videos since they tend to have intensive scene ***,in such videos,the keyframe information from a longer time span is less relevant to the previous,which could also cause learning conflict and deteriorate the model ***,the learning scheme is usually incapable of handling complex pattern *** solve this problem,we propose a divide-and-conquer framework,which can convert a complex problem domain into multiple simple ***,we devise a novel background consistency analysis(BCA)which effectively divides the mined frames into disjoint *** for each group,we assign an individual deep model on it to capture its key attribute during the fine-tuning *** the testing phase,we design a model-matching strategy,which could dynamically select the best-matched model from those fine-tuned ones to handle the given testing *** experiments show that our method can adapt severe background appearance variation coupling with object movement and obtain robust saliency detection compared with the previous scheme and the state-of-the-art methods.

关键词： Video salient object detection background consistency analysis weakly supervised learning long-term information background shift.

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Impact of High sodium Diet on Neovascularization and Osseointegration around Titanium Implant:An in Vivo and in Vitro Study

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Biomedical and Environmental Sciences 2024年第7期37卷 739-753页

作者： Keyuan Xu Xiaoting Tang yun Xiang Yiding Shen Zhennan Deng Pingping Ma Xinkun Shen Department of Orthopaedics The Third Affiliated Hospital of Wenzhou Medical University(Ruian People’s Hospital)Wenzhou 325016ZhejiangChina School and Hospital of Stomatology Wenzhou Medical UniversityWenzhou 325027ZhejiangChina

Objective A high sodium(HS)diet is believed to affect bone metabolism *** its impact on osseointegration of titanium(Ti)implants holds significant implications for postoperative dietary management of implanted *** This investigation probed the impact of sodium ions(Na^(+))on neovascularization and osteogenesis around Ti implants in vivo,utilizing micro-computed tomography,hematoxylin and eosin staining,and immunohistochemical ***,in vitro experiments assessed the effects of varied Na^(+)concentrations and exposure durations on human umbilical vein endothelial cells(HUVECs)and MC3T3-E1 *** In vivo,increased dietary sodium(0.8%-6.0%)led to a substantial decline in CD34 positive HUVECs and new bone formation around Ti implants,alongside an increase in inflammatory *** vitro,an increase in Na^(+)concentration(140-150 mmol/L)adversely affected the proliferation,angiogenesis,and migration of HUVECs,especially with prolonged *** MC3T3-E1 cells initially exhibited less susceptibility to high Na^(+)concentrations compared to HUVECs during short-term exposure,prolonged exposure to a HS environment progressively diminished their proliferation,differentiation,and osteogenic *** These findings suggest that HS diet had a negative effect on the early osseointegration of Ti implants by interfering with the process of postoperative vascularized bone regeneration.

关键词： High-sodium Implants Vascularization Osseointegration

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Vision Transformers with Hierarchical Attention

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Machine Intelligence Research 2024年第4期21卷 670-683页

作者： yun Liu Yu-Huan Wu Guolei Sun Le Zhang Ajad Chhatkuli Luc Van Gool Institute for Infocomm Research(I2R) A*STARSingapore 138632Singapore Institute of High Performance Computing(IHPC) A*STARSingapore 138632Singapore Computer Vision Lab ETH ZürichZürich 8092Switzerland School of Information and Communication Engineering University of Electronic Science and Technology of China(UESTC)Chengdu 611731China

This paper tackles the high computational/space complexity associated with multi-head self-attention(MHSA)in vanilla vision *** this end,we propose hierarchical MHSA(H-MHSA),a novel approach that computes self-attention in a hierarchical ***,we first divide the input image into patches as commonly done,and each patch is viewed as a ***,the proposed H-MHSA learns token relationships within local patches,serving as local relationship ***,the small patches are merged into larger ones,and H-MHSA models the global dependencies for the small number of the merged *** last,the local and global attentive features are aggregated to obtain features with powerful representation *** we only calculate attention for a limited number of tokens at each step,the computational load is reduced ***,H-MHSA can efficiently model global relationships among tokens without sacrificing fine-grained *** the H-MHSA module incorporated,we build a family of hierarchical-attention-based transformer networks,namely *** demonstrate the superiority of HAT-Net in scene understanding,we conduct extensive experiments on fundamental vision tasks,including image classification,semantic segmentation,object detection and instance ***,HAT-Net provides a new perspective for vision *** and pretrained models are available at https://***/yun-liu/HAT-Net.

关键词： Vision transformer hierarchical attention global attention local attention scene understanding.

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Rethinking Global Context in Crowd Counting

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Machine Intelligence Research 2024年第4期21卷 640-651页

作者： Guolei Sun yun Liu Thomas Probst Danda Pani Paudel Nikola Popovic Luc Van Gool Computer Vision Lab ETH ZürichZürich 8092Switzerland Institute for Infocomm Research A*STARSingapore 138632Singapore Magic Leap Zürich 8050Switzerland

This paper investigates the role of global context for crowd ***,a pure transformer is used to extract features with global information from overlapping image *** by classification,we add a context token to the input sequence,to facilitate information exchange with tokens corresponding to image patches throughout transformer *** to the fact that transformers do not explicitly model the tried-and-true channel-wise interactions,we propose a token-attention module(TAM)to recalibrate encoded features through channel-wise attention informed by the context *** that,it is adopted to predict the total person count of the image through regression-token module(RTM).Extensive experiments on various datasets,including ShanghaiTech,UCFQNRF,JHU-CROWD++and NWPU,demonstrate that the proposed context extraction techniques can significantly improve the performanceover the baselines.

关键词： Crowd counting vision transformer global context attention density map.

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Electrolyte Effect on Photoetching of Gallium Nitride

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Nanomanufacturing and Metrology 2024年第1期7卷 61-74页

作者： Huiqiang Liang Zhenghao Wei Jiongchong Fang Yanming Li Changli Li Zhirun Xie yun Hau Ng Guosong Zeng Shenzhen Key Laboratory of Intelligent Robotics and Flexible Manufacturing Systems Southern University of Science and TechnologyShenzhen 518055People’s Republic of China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055People’s Republic of China School of Materials Sun Yat-Sen UniversityGuangzhou 510275People’s Republic of China School of Energy and Environment City University of Hong KongKowloon 999077Hong Kong SARPeople’s Republic of China City University of Hong Kong Shenzhen Research Institute Shenzhen Hi-Tech Industrial ParkNanshan DistrictShenzhen 518000People’s Republic of China SUSTech Energy Institute for Carbon Neutrality Southern University of Science and TechnologyShenzhen 518055People’s Republic of China

The limited material removal rate of conventional chemical mechanical polishing(CMP)significantly hinders the fabrica-tion efficiency and surface quality,thereby preventing the development of gallium nitride(GaN)-based ***,the incorporation of photoelectrochemistry in CMP has garnered increasing attention because of its potential to enhance the quality and efficiency of the GaN ***,a considerable gap still exists in the comprehensive understanding of the specific photoelectrochemical(PEC)behavior of ***,we report the influence of the electrolyte on the PEC etching of *** acids and bases were tested,with their pH being carefully *** concentrations of the cations and anions were also *** results showed that photocorrosion/photoetching was more pronounced in sulfuric acid,phosphoric acid,and nitric acid environments than in alkaline environments,but it was less pronounced in hydrochloric ***,the effects of pH and anion concentration on photoetching were investigated,and the results revealed that pho-toetching in acidic environments weakened with increasing pH levels and diminished with increasing sulfate *** underlying reasons contributing to this observation were *** findings provide ideas for improving the pho-toetching efficiency of GaN,thereby enriching the photoelectrochemical mechanical polishing(PECMP)technology of GaN.

关键词： GaN Photoelectrochemistry Photoetching pH

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