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

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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 well.However,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 screen.To 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 method.According to the combined motion of particles and fluids,the influence of the internal flow state on particle motion and accumulation was analyzed.The 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 clogging.In 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 unit.In 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 opening.In 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 rate.The 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 and sand prevention selection.

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

Deep Guided Attention Network for Joint Denoising and Demosaicing in Real Image

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Chinese Journal of Electronics 2024年第1期33卷 303-312页

作者： tao ZHANG Ying fu Jun ZHANG School of Computer Science and Technology Beijing Institute of Technology Advanced Reasearch Institute of Multidisciplinary Science Beijing Institute of Technology

Denoising(DN) and demosaicing(DM) are the first crucial stages in the image signal processing pipeline. Recently, researches pay more attention to solve DN and DM in a joint manner, which is an extremely undetermined inverse problem. Existing deep learning methods learn the desired prior on synthetic dataset, which limits the generalization of learned network to the real world data. Moreover, existing methods mainly focus on the raw data property of high green information sampling rate for DM, but occasionally exploit the high intensity and signalto-noise(SNR) of green channel. In this work, a deep guided attention network(DGAN) is presented for real image joint DN and DM(JDD), which considers both high SNR and high sampling rate of green information for DN and DM, respectively. To ease the training and fully exploit the data property of green channel, we first train DN and DM sub-networks sequentially and then learn them jointly, which can alleviate the error accumulation. Besides, in order to support the real image JDD, we collect paired raw clean RGB and noisy mosaic images to conduct a realistic dataset. The experimental results on real JDD dataset show the presented approach performs better than the state-of-the-art methods, in terms of both quantitative metrics and qualitative visualization.

关键词： Image denoising Image demosaicing Joint processing Guided attention Paired real dataset

Control of fine particulate nitrate during severe winter haze in“2+26”cities

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Journal of Environmental Sciences 2024年第2期136卷 261-269页

作者： Chuang Qin Xiao fu tao Wang Jian Gao Jiaqi Wang Institute of Environment and Ecology Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Department of Civil and Environmental Engineering Hong Kong Polytechnic UniversityHong Kong 99907China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 10084China

The“2+26”cities,suffering the most severe winter haze pollution,have been the key region for air quality improvement in China.Increasing prominent nitrate pollution is one of the most challenging environmental issues in this region,necessitating development of an effective control strategy.Herein,we use observations,and state-of-the-art model simulations with scenario analysis and process analysis to quantify the effectiveness of the future SO_(2)-NO_(X)-VOC-NH_(3) emission control on nitrate pollution mitigation in“2+26”cities.Focusing on a serious winter haze episode,we find that limited NO_(X)emission reduction alone in the short-term period is a less effective choice than VOC or NH_3emission reduction alone to decrease nitrate concentrations,due to the accelerated NO_(X)-HNO_(3)conversion by atmospheric oxidants and the enhanced HNO_(3)to NO_(3)^(-)partition by ammonia,although deep NO_(X)emission reduction is essential in the long-term period.The synergistic NH_(3) and VOC emission control is strongly recommended,which can counteract the adverse effects of nonlinear photochemistry and aerosol chemical feedback to decrease nitrate more.Such extra benefits will be reduced if the synergistic NH_(3) and VOC reduction is delayed,and thus reducing emission of multiple precursors is urgently required for the effective control of increasingly severe winter nitrate pollution in“2+26”cities.

关键词： Nitrate Winter haze pollution Emission reduction “2+26”cities

Availability analysis of private cloud safety computer platform based on the Markov process

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Transportation Safety and Environment 2024年第1期6卷 103-108页

作者： Limin fu Jiakun wen Southwest Jiaotong University The School of Information Science&TechnologyChengduSichuan 610097China CRSC Research&Design Institute Group Co. LtdBeijing 100070China

To ensure the correctness of train control system design and development,the ways of simulation,test and formalization were compared.According to the safe critical attribute of train control system,the characters related to system safety were propounded such as real time,hybrid,distribution(concurrence)and reactivity,and the specific formal methods associated with every character were introduced in details.The analysis and classification of the methods were done based on their mathematical basis and applications,and their advantages and disadvantages were given.Analysis result indicates that every method has determinate limitations,which is determined by the essences of model checking and theory proving.It is pointed out that the presentation of new method,the expansion of existing methods and the integration of many methods will be the development trend of formalization in train control system.

关键词： safety computer Markov process cloud computing availability analysis

ALKBH5 suppresses autophagic flux via N6-methyladenosine demethylation of ZKSCAN3 mRNA in acute pancreatitis

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World Journal of Gastroenterology 2024年第12期30卷 1764-1776页

作者： tao Zhang Shuai Zhu Geng-wen Huang Department of General Surgery Xiangya HospitalCentral South UniversityChangsha 410005HunanChina. National Clinical Research Center for Geriatric Disorders Xiangya HospitalCentral South UniversityChangsha 410005HunanChina.

BACKGROUND Increasing evidence has demonstrated that N6-methyladenosine(m6A)RNA modification plays an essential role in a wide range of pathological conditions.Impaired autophagy is a critical hallmark of acute pancreatitis(AP).AIM To explore the role of the m6A modification of ZKSCAN3 in the regulation of autophagy in AP.METHODS The AP mouse cell model was established by cerulein-treated mouse pancreatic acinar cells(MPC-83),and the results were confirmed by the levels of amylase and inflammatory factors.Autophagy activity was evaluated by specific identification of the autophagy-related microstructure and the expression of autophagy-related genes.ZKSCAN3 and ALKBH5 were knocked down to study the function in AP.A m6A RNA binding protein immunoprecipitation assay was used to study how the m6A modification of ZKSCAN3 mRNA is regulated by ALKBH.RESULTS The increased expression of amylase and inflammatory factors in the supernatant and the accumulation of autophagic vacuoles verified that the AP mouse cell model was established.The downregulation of LAMP2 and upregulation of LC3-II/I and SQSTM1 demonstrated that autophagy was impaired in AP.The expression of ZKSCAN3 was upregulated in AP.Inhibition of ZKSCAN3 increased the expression of LAMP2 and decreased the expression of the inflammatory factors,LC3-II/I and SQSTM1.furthermore,ALKBH5 was upregulated in AP.Knockdown of ALKBH5 downregulated ZKSCAN3 expression and restored decreased autophagic flux in AP.Notably,the bioinformatic analysis revealed 23 potential m6A modification sites on ZKSCAN3 mRNA.The m6A modification of ZKSCAN3 mRNA was significantly decreased in AP.Knockdown of ALKBH5 increased the modification of ZKSCAN3 mRNA,which confirmed that ALKBH5 upregulated ZKSCAN3 expression in a m6A-dependent manner.CONCLUSION ALKBH5 inhibits autophagic flux through m6A demethylation of ZKSCAN3 mRNA in AP,thereby aggravating the severity of the disease.

关键词： Acute pancreatitis Autophagy ZKSCAN3 N6-methyladenosine ALKBH5

Study on a conical bearing for acceleration-sensitive equipment

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 103-128页

作者： Pang Hui Xu wen Dai Junwu Jiang tao Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China School of Civil Engineering and Transportation Beihua UniversityJilin 132013China

Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during earthquakes.However,isolation strategies give less attention to acceleration-sensitive systems or equipment.Meanwhile,as the isolation layer’s displacement grows,the stiffness and frequency of traditional rolling and sliding isolation bearings increases,potentially causing self-centering and resonance concerns.As a result,a new conical pendulum bearing has been selected for acceleration-sensitive equipment to increase self-centering capacity,and additional viscous dampers are incorporated to enhance system damping.Moreover,the theoretical formula for conical pendulum bearings is supplied to analyze the device’s dynamic parameters,and shake table experiments are used to determine the proposed device’s isolation efficiency under various conditions.According to the test results,the newly proposed devices have remarkable isolation performance in terms of minimizing both acceleration and displacement responses.Finally,a numerical model of the isolation system is provided for further research,and the accuracy is demonstrated by the aforementioned experiments.

关键词： seismic isolation acceleration-sensitive equipment the conical pendulum bearing shake table tests isolation performance,numerical model

The Influence of the Sun and Moon on the Observation of Very High Energy Gamma-ray Sources Using EAS Arrays

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Research in Astronomy and Astrophysics 2024年第6期24卷 247-254页

作者： tao wen Songzhan Chen Benzhong Dai School of Physics and Astronomy Yunnan University Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Tianfu Cosmic Ray Research Center

With great advance of ground-based extensive air shower arrays, such as LHAASO and HAWC, many very high energy(VHE) gamma-ray sources have been discovered and are being monitored regardless of the day and the night. Hence, the Sun and Moon would have some impacts on the observation of gamma-ray sources, which have not been taken into account in previous analysis. In this paper, the influence of the Sun and Moon on the observation of very high energy gamma-ray sources when they are near the line of sight of the Sun or Moon is estimated. The tracks of all the known VHE sources are scanned and several VHE sources are found to be very close to the line of sight of the Sun or Moon during some period. The absorption of very high energy gamma rays by sunlight is estimated with detailed method and some useful conclusions are achieved. The main influence is the block of the Sun and Moon on gamma rays and the shadow on the cosmic ray background. The influence is investigated considering the detector angular resolution and some strategies on data analysis are proposed to avoid the underestimation of the gamma-ray emission.

关键词： astroparticle physics methods: observational Sun: general Sun: UV radiation

Cationic engineered nanodiamonds for efficient antibacterial surface with strong wear resistance

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Nano Research 2024年第3期17卷 939-948页

作者： fu-Kui Li wen-Bo Zhao Yong Wang wen-tao Huang Ya-Lun Ku Hang Liu Rui Guo Hui-Hui Yu Kai-Kai Liu Chong-Xin Shan Henan Key Laboratory of Diamond Optoelectronic Materials and Devices Key Laboratory of Materials PhysicsMinistry of Educationand School of Physics&MicroelectronicsZhengzhou UniversityZhengzhou 450052China

The spread of diseases caused by bacterial adhesion and immobilization in public places constitutes a serious threat to public health.Prevention of bacteria spread by the construction of an antibacterial surface takes precedence over post-infection treatment.Herein,we demonstrate an effective antibacterial surface with strong wear resistance by constructing cationic engineered nanodiamonds(C-NDs).The C-NDs with positive surface potentials interact effectively with bacteria through electrostatic interactions,where the C-NDs act on the phospholipid bilayer and lead to bacterial membrane collapse and rupture through hydrogen bonding and residual surface oxygen-containing reactive groups.In this case,bactericidal rate of 99.99%and bacterial biofilm inhibition rate of more than 80%can be achieved with the C-NDs concentration of 1 mg/mL.In addition,the C-NDs show outstanding antibacterial stability,retaining over 87%of the antibacterial effect after stimulation by adverse environments of heat,acid,and external abrasion.Therefore,an antibacterial surface with high wear resistance obtained by integrating C-NDs with commercial plastics has been demonstrated.The antibacterial surface with a mass fraction of 1 wt.%C-NDs improved abrasion resistance by 3981 times,with 99%killing of adherent bacteria.This work provides an effective strategy for highly efficient antibacterial wear-resistant surface,showing great practical applications in public health environments.

关键词： antibacterial surface cationic engineered nanodiamonds wear-resistant

Significantly Enhanced Melt Memory Effect of Metallocene-made Isotactic Polypropylene Containing Talc

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Chinese Journal of Polymer Science 2024年第2期42卷 213-222,I0008页

作者： Hong-wen Sun fu-Shan Wang Yan Gao fu-Qing Wei Jia-Chun Feng State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai200433China Lanzhou Petrochemical Corporation of PetroChina Lanzhou730060China Lanzhou Petrochemical Research Center Petrochemical Research Institute of PetroChinaLanzhou730060China

The melt memory effect is a widely observed phenomenon in semi-crystalline polymers. In practical applications, various additives are usually introduced into polymers, which may affect their melt memory behavior. In this work, the effect of talc on the melt memory effect of metallocene-made isotactic polypropylene(M-PP) was investigated in detail by using the differential scanning calorimetry. The results indicated that the introduction of talc significantly strengthened the melt memory effect of M-PP. Specifically, the upper limit temperature of Domain II increased from 161 ℃ to 174 ℃, resulting in a substantial widening of the temperature range of Domain IIa from 1 ℃ to 14 ℃. Analysis of the crystal orientation of the M-PP containing talc cooled from various Ts suggested that the remarkably enhanced melt memory effect could be ascribed to the stabilization of oriented nuclei facilitated by talc. This stabilizing effect was likely attributable to the prefreezing effect or the sorption interaction between talc and the M-PP chains.

关键词： Metallocene-made isotactic polypropylene Talc Melt memory effect Crystal orientation