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

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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

Mycorrhizal fungi mitigate nitrogen losses of an experimental grassland by facilitating plant uptake and soil microbial immobilization

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Pedosphere 2024年第2期34卷 399-410页

作者： Yangyang JIA Marcel G.A.VAN DER HEIJDEN Alain Y.VALZANO-HELD Markus JOCHER Florian WALDER Postdoctoral Mobile Station of Ecology College of Ecology and EnvironmentXinjiang UniversityÜrümqi 830046China research group Plant-Soil Interactions AgroscopeZürich 8046Switzerland research group Climate and Agriculture AgroscopeZürich 8046Switzerland Department of Plant and Microbial Biology University of ZürichZürich 8008Switzerland research group Soil Quality and Soil Use AgroscopeZürich 8046Switzerland

Nitrogen(N)is one of the most limited nutrients of terrestrial ecosystems,whose losses are prevented in tightly coupled cycles in finely tuned *** change-induced N enrichment through atmospheric deposition and application of vast amounts of fertilizer are now challenging the terrestrial N *** mycorrhizal fungi(AMF)are known drivers of plant-soil nutrient fluxes,but a comprehensive assessment of AMF involvement in N cycling under global change is still ***,we simulated N enrichment by fertilization(low/high)in experimental grassland microcosms under greenhouse conditions in the presence or absence of AMF and continuously monitored different N pathways over nine *** found that high N enrichment by fertilization decreased the relative abundance of legumes and the plant species dominating the plant community changed from grasses to forbs in the presence of AMF,based on aboveground *** presence of AMF always maintained plant N:phosphorus(P)ratios between 14 and 16,no matter how the soil N availability *** in plant N:P ratios due to the increased plant N and P uptake might thus be a primary pathway of AMF altering plant community ***,we constructed a comprehensive picture of AMF’s role in N cycling,highlighting that AMF reduced N losses primarily by mitigating N leaching,while N_(2)O emissions played a marginal *** mycorrhizal fungi reduced N_(2)O emissions directly through the promotion of N_(2)O-consuming *** underlying mechanism for reducing N leaching is mainly the AMF-mediated improved nutrient uptake and AMF-associated microbial *** results indicate that synergies between AMF and other soil microorganisms cannot be ignored in N cycling and that the integral role of AMF in N cycling terrestrial ecosystems can buffer the upcoming global changes.

关键词： N cycling N enrichment N uptake N:P ratio plant community structure symbiotic soil fungi

Pathway Planning of Nuclear Power Development Incorporating Assessment of Nuclear Event Risk

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 500-513页

作者： Xinxin Yang Yusheng Xue Bin Cai School of Electrical Engineering Southeast UniversityNanjingChinaand they are also with State Grid Electric Power Research Institute(NARI Group Corporation)NanjingChina State Key Laboratory of Smart Grid Protection and Operation Control NanjingChina State Grid Electric Power research Institute(NARI group Corporation) NanjingChina

The nuclear event risk(NER)is an important and disputed factor that should be reasonably considered when planning the pathway of nuclear power development(NPD)to assess the benefits and risks of developing nuclear power more *** paper aims to explore the impact of nuclear events on NPD pathway *** influence of nuclear events is quantified as a monetary risk component,and an optimization model that incorporates the NER in the objective function is *** optimize the pathway of NPD in the lowcarbon transition course of power supply structure evolution,a simulation model is built to deduce alternative NPD pathways and corresponding power supply evolution scenarios under the constraint of an exogenously assigned carbon emission pathway(CEP);moreover,a method is proposed to describe the CEP by superimposing the maximum carbon emission space and each carbon emission reduction(CER)component,and various CER components are clustered considering the emission reduction characteristics and resource endowments of different power generation technologies.A case study is conducted to explore the impact of NER and its risk valuation uncertainty on NPD pathway *** method presented in this paper allows the impact of nuclear events on NPD pathway planning to be quantified and improves the level of coordinated optimization of benefits and risks.

关键词： Low-carbon transition power supply structure evolution nuclear power development(NPD) quantitative analysis nuclear event risk evaluation

Online review driven route planning of green cold chain logistics: considering service attribute preference

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Journal of Traffic and transportation Engineering(English Edition) 2024年

作者： Qubo Yu Xuze Ye Xueying Jiang Shaoquan Ni Kun Liu Xiaowei Liu School of transportation and Logistics， Southwest Jiaotong University New Corridor Logistics group Co.， Ltd.of Sichuan Port and Shipping Investment National Engineering Laboratory of Integrated transportation Big Data Application Technology， Southwest Jiaotong University

For the long-distance cold chain transportation， this study focuses on green route planning in the cold chain multimodal transport network， considering the customers’ preferences on transport service attributes. To extract customers' preferences from online reviews， we build the bidirectional gated recurrent units (biGRU) and Logit framework. The coefficients representing the preferences for transport service attributes are calculated and integrated into the route planning model. To enhance the reliability of the routes， we utilize fuzzy set theories to describe travel time， transport cost coefficient， and capacity as trapezoidal fuzzy numbers. Then， we develop a fuzzy route planning model aims to minimize transportation cost， damage cost， refrigeration cost， carbon emission cost， and reliability cost. The numerical experiments are conducted on the new land and sea corridor in southwest China. The proposed method can plan the route which meet the customers’ preferences on transportation cost， travel time， reliability and carbon emission. Moreover， logistics companies can strike a balance between cost and reliability by setting confidence coefficients for travel time and capacity. Furthermore， carbon trading policy implements the significant effect on carbon emission reduction in cold chain logistics， when the trading price is 2 RMB per unit.

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Technical review of electric vehicle charging distribution models with considering driver behaviors impacts

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Journal of Traffic and transportation Engineering(English Edition) 2024年第4期11卷 643-666页

作者： Wei Lin Heng Wei Lan Yang Xiangmo Zhao ART-EngineS transportation research Laboratory Department of Civil and Architectural Engineering and Construction ManagementUniversity of CincinnatiCincinnatiOH 45221USA School of Information Engineering Chang'an UniversityXi'an 710064China

Amassive market penetration of electric vehicles(EVs)associated with nonnegligible energy consumption and environmental issues has imposed a big challenge on evaluating electrical power distribution and related transportation facilities improvement in response to the largescale EV charging service *** deployment of EV charging stations including location and determination ofnumber of slowcharging stations and fast charging stationshas become an emerging concern and one of the most pressing needs in *** paper conducts a comprehensive survey of EV charging demand and distribution models with consideration of realistic driver behaviors *** is currently a shortage in academic literature,but indeed has drawn practical attention in the strategic planning *** address the need,this paper presents an in-depth literature review of relevant studies that have identified different types of EV charging facilities,needs or concerns that are considered into EV charging demand and distribution modeling,alongside critical impacting factor identification,mathematical relationshipsof the contributing factorsandEVchargingdemand and distribution *** findings from the current literature are summarized with strategies for optimized plan of charging station deployments(i.e.,location and related number of charging station),in an attempt to provide a valuable reference for interested readers.

关键词： Charging demand estimation Strategic charging station deployment Electric vehicle Driver behavior

Dietary supplementation of zinc oxide modulates intestinal functionality during the post-weaning period in clinically healthy piglets

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Journal of Animal Science and Biotechnology 2024年第1期15卷 313-328页

作者： Dirkjan Schokker Soumya K.Kar Els Willems Alex Bossers Ruud A.Dekker Alfons J.M.Jansman Wageningen Bioveterinary research LelystadThe Netherlands Wageningen Livestock research Wageningen University&ResearchWageningenThe Netherlands Royal Agrifirm group ApeldoornThe Netherlands Institute for Risk Assessment Sciences Utrecht UniversityUtrechtThe Netherlands

Background To improve our understanding of host and intestinal microbiome interaction,this research investigated the effects of a high-level zinc oxide in the diet as model intervention on the intestinal microbiome and small intestinal functionality in clinically healthy post-weaning *** study 1,piglets received either a high concentration of zinc(Zn)as zinc oxide(Zn O,Zn,2,690 mg/kg)or a low Zn concentration(100 mg/kg)in the diet during the post weaning period(d 14–23).The effects on the piglet's small intestinal microbiome and functionality of intestinal tissue were *** study 2,the impact of timing of the dietary zinc intervention was investigated,i.e.,between d 0–14 and/or d 14–23 post weaning,and the consecutive effects on the piglet's intestinal functionality,here referring to microbiota composition and diversity and gene expression *** Differences in the small intestinal functionality were observed during the post weaning period between piglets receiving a diet with a low or high concentration Zn O content.A shift in the microbiota composition in the small intestine was observed that could be characterized as a non-pathological change,where mainly the commensals *** the immediate post weaning period,i.e.,d 0–14,the highest number of differentially expressed genes(DEGs)in intestinal tissue were observed between animals receiving a diet with a low or high concentration Zn O content,i.e.,23 DEGs in jejunal tissue and 11 DEGs in ileal *** genes are involved in biological processes related to immunity and inflammatory *** example,genes CD59 and REG3G were downregulated in the animals receiving a diet with a high concentration Zn O content compared to low Zn O content in both jejunum and ileum *** the second study,a similar result was obtained regarding the expression of genes in intestinal tissue related to immune pathways when comparing piglets receiving a diet with a high concentration Zn O con

关键词： Immune system Intestinal functionality Microbiota Piglets Zinc oxide

A review of vehicle detection methods based on computer vision

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Journal of Intelligent and Connected Vehicles

Journal of Intelligent and Connected Vehicles 2024年第1期7卷 1-18页

作者： Changxi Ma Fansong Xue School of Traffic and transportation Lanzhou Jiaotong UniversityLanzhou 730070China Key Laboratory of Railway Industry on Plateau Railway transportation Intelligent Management and Control Lanzhou 730070China

With the increasing number of vehicles,there has been an unprecedented pressure on the operation and maintenance of intelligent transportation systems and transportation *** order to achieve faster and more accurate identification of traffic vehicles,computer vision and deep learning technology play a vital role and have made significant *** study summarizes the current research status,latest findings,and future development trends of traditional detection algorithms and deep learning-based detection *** the detection algorithms based on deep learning,this study focuses on the representative convolutional neural network ***,it examines the two-stage and one-stage detection algorithms,which have been extensively utilized in the field of intelligent transportation *** to traditional detection algorithms,deep learning-based detection algorithms can achieve higher accuracy and *** single-stage detection algorithm is more efficient for real-time detection,while the two-stage detection algorithm is more accurate than the single-stage detection *** the follow-up research,it is important to consider the balance between detection efficiency and detection ***,vehicle missed detection and false detection in complex scenes,such as bad weather and vehicle overlap,should be taken into *** will ensure better application of the research findings in engineering practice.

关键词： intelligent transportation system computer vision deep learning vehicle detection object detection algorithm

A new targeted on-ramp control approach considering both efficiency and equity

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transportation Safety and Environment 2024年第3期6卷 85-95页

作者： Shengnan Li Minglun Li Jianjun Dai Pu Wang School of Traffic and transportation Engineering Central South UniversityChangsha 410075HunanChina Hunan Communications research Institute Co. LtdChangsha 410015HunanChina

On-ramp control is an effective approach for alleviating traffic congestion on ***,there is still a lack of on-ramp control approaches applicable to large regional highway ***,we develop a targeted on-ramp control approach applicable to regional highway networks by taking advantage of the vehicle source information,which pinpoints the on-ramps contributing major traffic flow to the highway ***,a combined and tunable controlling index is proposed to enhance the equity of the generated traffic control *** proposed on-ramp control approach is validated on an actual large highway network using actual travel demand *** indicate that the proposed approach can well mitigate the traffic congestion of highway bottleneck while at the same time enhancing the equity and practicability of the generated traffic control scheme.

关键词： on-ramp control vehicle source traffic congestion equity

Simulation of fire emergency evacuation in a large-passenger-flow subway station based on the on-site measured data of Shenzhen Metro

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transportation Safety and Environment 2024年第1期6卷 47-55页

作者： Hua Chen Chenyang Zhang Jieyu Zhang Ya Shu Xinjian Qi Chaozhe Jiang Sichuan FAST Fire Safety Assessment Co. LTD.Chengdu 610036SichuanChina School of transportation and Logistics Southwest Jiaotong UniversityChengdu 611756SichuanChina Sichuan Fire research Institute of MEM Chengdu 610036SichuanChina Shenzhen Metro group Co. LTD.Shenzhen 518026GuangdongChina

Because of its large capacity,high efficiency and energy savings,the subway has gradually become the primary mode of transportation for citizens.A high density of passengers exists within a large-passenger-flow subway station,and the number of casualties and injuries during a fire emergency is *** this paper,Pathfinder software and on-site measured data of Pingzhou station in Shenzhen(China)were utilized to simulate a fire emergency evacuation in a large-passenger-flow subway *** Required Safe Egress Time(RSET),number of passengers and flow rates of stairs and escalators were analysed for three fire evacuation scenarios:train fire,platform fire and hall *** evacuation time of the train fire,which was 1173 s,was the longest,and 3621 occupants needed to evacuate when the train was fully *** could not complete the evacuation within 6 mins in all three fire evacuation scenarios,which does not meet the current standard requirements and *** changing the number of passengers and the number of stairs for evacuation,the flow rate capacity and evacuation time were explored,which have reference values for safety management and emergency evacuation plan optimization during peak hours of subway operation.

关键词： fire emergency evacuation large-passenger-flow subway station on-site measured data Pathfinder