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Influence of pressure disturbance wave on dynamic response characteristics of liquid film seal for multiphase pump

Petroleum Science 2024年第3期21卷 2048-2065页

作者： Qing-Ping Li Jin-ya zhang Jia-Xiang zhang Yong-Xue zhang CNOOC Research Institute Company Limited Beijing100028China State Key Laboratory of Natural Gas Hydrate Beijing100028China College of Mechanical and Transportation Engineering China University of PetroleumBeijing2249China

Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump *** mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation ***(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh *** results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually *** the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely *** maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance *** mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial *** with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and *** actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.

关键词： Multiphase pump Liquid film seal Pressure disturbance wave Dynamic response characteristics

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Fixed-Time Anti-Disturbance Average-Tracking for Multi-Agent Systems Without Velocity Measurements

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Journal of Systems Science & Complexity 2024年第3期37卷 985-1002页

作者： LI Yuling LIU Chenglin zhang ya CHEN yangyang Key Laboratory of Advanced Process Control for Light Industry(Ministry of Education) Institute of AutomationJiangnan UniversityWuci 214122China School of Automation Southeast UniversityNanjing 210096China

In this paper,the authors tackle a fixed-time average-tracking problem for multi-agent systems which do not require velocity measurements and are affected by external mismatched and matched *** objective requires the considered agents with second-order dynamics to follow the average value of several time-varying reference signals,each of which is acquired by only one *** of all,the average value is estimated by using a novel distributed average estimator in a fixed ***,an original observer is created to provide estimated values in a fixed time for external mismatched and matched disturbances as well as unmeasured velocities of ***,the authors propose a novel fixed-time anti-disturbance average-tracking protocol with the aid of the observer and a sliding mode *** the end,the feasibility of theoretical analysis is illustrated by some simulation experiments.

关键词： Average-tracking control fixed-time algorithm fixed-time observer mismatched distur-bances multi-agent systems velocity measurements

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Sex-biased adaptation shapes uniparental gene pools in Tibetans

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Science China(Life Sciences) 2024年第3期67卷 611-613页

作者： Min-Sheng Peng ya-Ping zhang State Key Laboratory of Genetic Resources and Evolution Kunming Institute of ZoologyChinese Academy of SciencesKunming 650201China KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases Kunming Institute of ZoologyChinese Academy of SciencesKunming 650201China Kunming College of Life Science University of Chinese Academy of SciencesKunming 650204China State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan School of Life SciencesYunnan UniversityKunming 650091China

During the past two decades, a series of archaeological and genetic investigations substantially improve our perception of the hominin settlement of the Tibetan Plateau(zhang et al., 2022). In addition to the identifi... 详细信息

关键词： Tibetan Plateau altitude

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Regional Multi-Agent Cooperative Reinforcement Learning for City-Level Traffic Grid Signal Control

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IEEE/CAA Journal of Automatica Sinica 2024年第9期11卷 1987-1998页

作者： Yisha Li ya zhang Xinde Li Changyin Sun School of Automation Southeast UniversityNanjing 210096 Key Laboratory of Measurement and Control of Complex Systems of Engineering Ministry of EducationSoutheast UniversityNanjing 210096China

This article studies the effective traffic signal control problem of multiple intersections in a city-level traffic system.A novel regional multi-agent cooperative reinforcement learning algorithm called RegionSTLight is proposed to improve the traffic *** a regional multi-agent Q-learning framework is proposed,which can equivalently decompose the global Q value of the traffic system into the local values of several regions Based on the framework and the idea of human-machine cooperation,a dynamic zoning method is designed to divide the traffic network into several strong-coupled regions according to realtime traffic flow *** order to achieve better cooperation inside each region,a lightweight spatio-temporal fusion feature extraction network is *** experiments in synthetic real-world and city-level scenarios show that the proposed RegionS TLight converges more quickly,is more stable,and obtains better asymptotic performance compared to state-of-theart models.

关键词： Human-machine cooperation mixed domain attention mechanism multi-agent reinforcement learning spatio-temporal feature traffic signal control

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Height and body mass index trajectories from 1975 to 2015 and prevalence of stunting,underweight and obesity in 2016 among children in Chinese cities:findings from five rounds of a national survey

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World Journal of Pediatrics 2024年第4期20卷 404-412页

作者： Xin‑Nan Zong Hui Li ya‑Qin zhang Department of Growth and Development Capital Institute of PediatricsBeijing 100020China

Background A more comprehensive assessment of growth and nutrition in children is required in China due to rapid socioeconomic *** aimed to investigate height and body mass index(BMI)trajectories from 1975 to 2015 and the prevalence of stunting and obesity in 2016 among children in Chinese *** A total of 904,263 children from birth to 6.9 years were collected from a series of nationally representative surveys in *** and BMI trajectories and prevalence of stunting,underweight,overweight and obesity were *** The average height level of Chinese urban children under 7 years presented a positive secular trend from 1975 to 2015;however,a slowing tendency occurred in 2005‒*** apparent increase was observed at the 5th,50th and 95th percentiles of BMI in urban children aged 3 years and older,with a more prominent increase at the 95th *** total prevalence of stunting and underweight under 7 years was 1.4%and 2.0%,*** total prevalence of overweight and obesity under 7 years was 12.6%and 4.3%,respectively,with 12.7%and 4.9%for boys,12.6%and 3.6%for girls,12.1%and 4.0%in urban areas and 13.1%and 4.5%in suburban rural *** The average height level of Chinese urban children has reached World Health Organization child growth standards since 2005 and presented a slowing tendency in secular trend in 2005‒*** attention and efforts and public health interventions should be urgently made to combat overweight and obesity among preschool children.

关键词： Body mass index Children Height Obesity Stunting

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The RFI Fast Mitigation Algorithm Based on Block LMS Filter

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Research in Astronomy and Astrophysics 2024年第1期24卷 265-272页

作者： Han Wu Hai-Long zhang ya-Zhou zhang Jie Wang Xu Du Ting zhang Xin-Chen Ye Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Radio Astronomy Chinese Academy of SciencesNanjing 210008China National Astronomical Data Center Beijing 100101China

The radio telescope possesses high sensitivity and strong signal collection *** receiving celestial radiation signals,it also captures Radio Frequency Interferences(RFIs)introduced by human ***,as signals originating from sources other than the astronomical targets,significantly impacts the quality of astronomical *** paper presents an RFI fast mitigation algorithm based on block Least Mean Square(LMS)*** enhances the traditional adaptive LMS filter by grouping L adjacent time-sampled points into one block and applying the same filter coefficients for filtering within each *** transformation reduces multiplication calculations and enhances algorithm efficiency by leveraging the time-domain convolution *** algorithm is tested using baseband data from the Parkes 64 m radio telescope's pulsar observations and simulated *** results confirm the algorithm's effectiveness,as the pulsar profile after RFI mitigation closely matches the original pulsar profile.

关键词： methods:data analysis techniques:interferometric (stars:)pulsars:individual(J0437-4715)

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Heavy metals potentially drive co-selection of antibiotic resistance genes by shifting soil bacterial communities in paddy soils along the middle and lower yangtze River

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Pedosphere 2024年第3期34卷 606-619页

作者： ya zhang Hao WANG Minghui HU Rui CAI Yuqing MIAO Xiancan ZHU Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Metabolic Diseases Anhui Provincial Key Laboratory of the Conservation and Exploitation of Biological ResourcesCollege of Life SciencesAnhui Normal UniversityWuhu 241000(China) School of Geography and Tourism Anhui Normal UniversityWuhu 241003(China)

Heavy metals(HMs)and antibiotic resistance have become serious environmental problems affecting soil and human *** microorganisms play key roles in pollutant degradation and biogeochemical cycling processes;however,the interactions among HMs,soil microbial communities,and antibiotic resistance genes(ARGs)in agricultural soils remain *** quantitative real-time polymerase chain reaction and NovaSeq sequencing,we evaluated heavy metal contents,abundances of ARGs,soil bacterial community structure and functions,and their correlations in paddy soils at 43 sampling sites along the middle and lower reaches of the yangtze River,central and eastern *** results showed the co-occurrence of HMs,ARGs,and HM resistance genes across all paddy ***,significant positive associations were detected between HMs and resistance ***,czcA,and int1 were positively correlated with bacterial community *** Mantel test showed that bacterial community composition and functions were significantly associated with HMs and resistance genes,such as Cd,Cr,Zn,copA,czcA,int1,and ***,HMs and ARGs were the major factors shaping soil bacterial communities;thus,HMs triggered proliferation of HM and antibiotic resistances by influencing the mobile genetic element(int1)and soil microbial *** study revealed that HMs potentially drive the co-selection of ARGs by shifting soil bacterial community structure and functions,thereby increasing the potential risks to human health as well as ecological environment in the paddy soils along the middle and lower reaches of the yangtze River.

关键词： agricultural ecosystem ecological risk heavy metal resistance microbial community soil contamination soil pollution

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Dynamic aggregation of carbon dots self-stabilizes symmetry breaking for exceptional hydrogen production with near-infrared light

Aggregate

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Aggregate 2024年第1期5卷 385-397页

作者： Qi zhang ya zhang Hu Shi Hongxia zhang Jianghong Zhao Zhanfeng Zheng Hengquan yang Pengju yang School of Chemistry and Chemical Engineering Shanxi UniversityTaiyuanChina Engineering Research Center of Ministry of Education for Fine Chemicals Shanxi UniversityTaiyuanChina Institute of Molecular Science Shanxi UniversityTaiyuanChina State Key Laboratory of Coal Conversion Institute of Coal ChemistryChinese Academy of SciencesTaiyuanChina

Developing new photosystems that integrate broad-band near-infrared(NIR)light harvesting and efficient charge separation is a long-sought goal in the photocatalytic *** this work,we develop a novel photochemical strategy to prepare light-active carbon dots(CDs)under room temperature and discover that the aggregation of CDs can broaden the light absorption to the NIR region due to the electronic couplings between neighboring ***,the dynamic noncovalent interactions within CD aggregates can stabilize symmetry breaking and thus induce large dipole moments for charge separation and ***,the weak non-covalent interactions allow for flexible design of the aggregated degrees and the local electronic structures of CD aggregates,further strengthening NIR-light harvesting and charge separation *** a result,the CD aggregates achieve a record apparent quantum yield of 13.5%at 800 nm,which is one of the best-reported values for NIR-light-driven hydrogen photosynthesis to ***,we have prepared a series of different CDs and also observed that these CDs after aggregation all exhibit outstanding NIR-responsive photocatalytic hydrogen production activity,suggesting the universality of aggregation-enhanced *** discovery opens a new promising platform for using CD aggregates as efficient light absorbers for solar conversion.

关键词： aggregation charge separation hydrogen production near-infrared light photocatalysis

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Shexiang Tongxin Dropping Pill Promotes Angiogenesis through VEGF/eNOS Signaling Pathway on Diabetic Coronary Microcirculation Dysfunction

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Chinese Journal of Integrative Medicine 2024年第10期30卷 886-895页

作者： CUI Xin-yu LIU Tian-hua BAI ya-li zhang Meng-di LI Guo-dong zhang Yu-ting YUAN Yue-ying zhang ya-wen YU Li-shuang HAN Li-na WU yan School of Traditional Chinese Medicine Beijing University of Chinese Medicine Key Laboratory of Traditional Chinese Medicine Syndrome and Formula Ministry of Education Beijing University of Chinese Medicine Beijing Research Institute of Chinese Medicine Beijing University of Chinese Medicine

Objective: To study the effect of Shexiang Tongxin Dropping Pill(STDP) on angiogenesis in diabetic cardiomyopathy mice with coronary microcirculation dysfunction(CMD). Methods: According to a random number table, 6 of 36 SPF male C57BL/6 mice were randomly selected as the control group, and the remaining 30 mice were injected with streptozotocin intraperitoneally to replicate the type 1 diabetes model. Mice successfully copied the diabetes model were randomly divided into the model group, STDP low-dose group [15 mg/(kg·d)], medium-dose group [30 mg/(kg·d)], high-dose group [60 mg/(kg·d)], and nicorandil group [15 mg/(kg·d)], 6 in each group. The drug was given by continuous gavage for 12 weeks. The cardiac function of mice in each group was detected at the end of the experiment, and coronary flow reserve(CFR) was detected by chest Doppler technique. Pathological changes of myocardium were observed by hematoxylin-eosin staining, collagen fiber deposition was detected by masson staining, the number of myocardial capillaries was detected by platelet endothelial cell adhesion molecule-1 staining, and the degree of myocardial hypertrophy was detected by wheat germ agglutinin staining. The expression of the vascular endothlial growth factor(VEGF)/endothelial nitric oxide synthase(eNOS) signaling pathway-related proteins in myocardial tissue was detected by Western blot. Results: Compared with the model group, medium-and high-dose STDP significantly increased the left ventricular ejection fraction and left ventricular fraction shortening(P<0.01), obviously repaired the disordered cardiac muscle structure, reduced myocardial fibrosis, reduced myocardial cell area, increased capillary density, and increased CFR level(all P<0.01). Western blot showed that high-dose STDP could significantly increase the expression of VEGF and promote the phosphorylation of vascular endothelial growth factor receptor 2, phosphoinositide 3-kinase, protein kinase B, and eNOS(P<0.05 or P<0.01). Co

关键词： Shexiang Tongxin Dropping Pill angiogenesis coronary microcirculation dysfunction diabetic cardiomyopathy type 1 diabetes

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Recovery and in-situ reduction of precious metals by graphdiyne and graphdiyne oxide for antibacterial use

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Rare Metals 2024年第4期43卷 1747-1757页

作者： Ming-Ji Jiang ya-Na zhang Ling-Shen Meng Jing Kang Yong-Jun Li Alideertu Dong College of Chemistry and Chemical Engineering Inner Mongolia UniversityHohhot010021China Engineering Research Center of Dairy Quality and Safety Control Technology Ministry of EducationInner Mongolia UniversityHohhot010021China Department of Chemistry University of ZurichCH-8057ZurichSwitzerland Laboratory of Organic Solids and Beijing National Laboratory for Molecular Sciences Institute of ChemistryChinese Academy of SciencesBeijing100190China

Based on the in-situ self-reduction and chemical stability,graphdiyne(GDY)and graphdiyne oxide(GDYO)are used as trapping agents to investigate the ability for recovering Au^(3+),Ag^+,and Pd^(2+)under different pH values and interfering *** strong acidity at pH=1,these two agents demonstrate high select recovery towards the three precious metal ions,which could be insitu reduced to nanoparticles(NPs).In addition,superparamagnetic Fe_(3)O_(4)NPs are deposited on the surfaces of GDY and *** magnetic responses enable GDYFe_(3)O_(4)to recover precious metals conveniently and efficiently by the aid of an external magnetic *** study also confirms the antibacterial activity of the as-recovered NPs deposited on GDY and GDYO against Escherichia coli and Staphylococcus aureus(1×10^(5)colony-forming unit(CFU)·mL^(-1)),and the antibacterial rates are 100%.This strategy of recovering precious metals and subsequently reusing to combat pathogens will be of great significance for environmental remediation and biomedical applications.

关键词： Graphdiyne In-situ reduction Recovery Precious metals Antibacterial

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