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Time-delay Correction Control Strategy for HVDC Frequency Regulation Services

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CSEE Journal of Power and Energy Systems 2024年第5期10卷 2027-2037页

作者： Yuqing Dong Kaiqi Sun Jinning Wang shunliang Wang He Huang Tianqi Liu Yilu Liu School of Electrical Engineering Shandong UniversityJinan 250061China School of Electrical Engineering Shandong UniversityJinan 250061China. department of Electrical Engineering and Computer Science University of TennesseeKnoxville 37996USA.

With the advancements in voltage source converter(VSC)technology,VSC based high voltage direct current(VSCHVDC)systems provide system operators with a prospective approach to enhance system operating stability and *** addition to long-distance transmission,the VSC-HVDC system can also provide multiple ancillary services,such as frequency regulation,due to its power ***,if a time delay exists in the control signal,the VSC-HVDC system may bring destabilizing influences to the system,which will decrease the system resilience under the *** order to reduce control deviation caused by time delay,in this paper,a small signal model is first conducted to analyze the impact of time delay on system *** a time-delay correction control strategy for HVDC frequency regulation control is developed to reduce the influence of the time *** control performance of the proposed time-delay correction control is verified both in the established small signal model and the runtime simulation in a modified IEEE 39 bus *** results indicate that the proposed time-delay correction control strategy shows significant improvement in system stability.

关键词： Frequency regulation control HVDC small signal analysis time delay time-delay correction control strategy

Evolution of pore systems in low-maturity oil shales during thermal upgrading--Quantified by dynamic SEM and machine learning

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Petroleum Science 2024年第3期21卷 1739-1750页

作者： Jun Liu Xue bai Derek Elsworth Key Laboratory of Deep Underground Science and Engineering(Ministry of Education) Institute of New Energy and Low-Carbon TechnologySichuan UniversityChengdu610065SichuanChina International Quantum Academy Shenzhen518048GuangdongChina Shenzhen Institute of Advanced Electronic Materials Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen518055GuangdongChina department of Energy and Mineral Engineering Pennsylvania State University ParkPA 16802USA

In-situ upgrading by heating is feasible for low-maturity shale oil,where the pore space dynamically *** characterize this response for a heated substrate concurrently imaged by *** systematically follow the evolution of pore quantity,size(length,width and cross-sectional area),orientation,shape(aspect ratio,roundness and solidity)and their anisotropy—interpreted by machine *** indicate that heating generates new pores in both organic matter and inorganic ***,the newly formed pores are smaller than the original pores and thus reduce average lengths and widths of the bedding-parallel pore ***,the average pore lengths and widths are increased in the bedding-perpendicular ***,heating increases the cross-sectional area of pores in low-maturity oil shales,where this growth tendency fluctuates at300℃.In addition,the orientation and shape of the newly-formed heating-induced pores follow the habit of the original pores and follow the initial probability distributions of pore orientation and ***,limited anisotropy is detected in pore direction and shape,indicating similar modes of evolution both bedding-parallel and *** propose a straightforward but robust model to describe evolution of pore system in low-maturity oil shales during heating.

关键词： Low-maturity oil shale Pore elongation Organic matter pyrolysis In-situthermal upgrading Scanning electron microscopy(SEM) Machine learning

Analytical model for predicting folding stable state of bistable deployable composite boom

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Chinese Journal of Aeronautics 2024年第8期37卷 460-469页

作者： Tianwei LIU Jiangbo bai Nicholas FANTUZZI School of Transportation Science and Engineering Beihang UniversityBeijing 100191China Jingdezhen Research Institute of Beihang university Jingdezhen 333000China DICAM department University of BolognaBologna 40136Italy

Bistable Deployable Composite Boom(Bi-DCB)can achieve bistable function by storing and releasing strain energy,which has a good application prospect in space *** example,it serves as the main support section of deployable structures(e.g.,solar arrays and antennas).This paper investigates folding stable state of Bi-DCB through the analytical *** on Archimedes’helix and energy principle,an analytical model for predicting folding stable state of Bi-DCB was *** failure index of Bi-DCB in folding stable state were analyzed using the Tsai-Hill criterion and the maximum stress ***,a 2.00 mm long Bi-DCB was fabricated using autoclave *** prediction results of the proposed model were compared with experiments and results of two other analytical *** is shown that the proposed model shows good prediction ***,the effect of geometric parameters on folding stable state of Bi-DCB was further investigated with the aid of the proposed model.

关键词： Bistable Deployable composite boom Solar arrays Antennas Archimedes’helix Folding Failure analysis

A Converse Theorem for Split SO_(2.) over Finite Fields

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Acta Mathematica Sinica,English Series 2024年第3期40卷 731-771页

作者： Alexander HAZELTINE bai Ying LIU department of Mathematics Purdue University150 N.University St.West LafayetteIN 47907USA E-mail:ahazelti@purdue.edu liu2053@purdue.edu

We prove a converse theorem for split even special orthogonal groups over finite *** is the only case left on converse theorems of classical groups and the difficulty is the existence of the outer automorphism. In thi... 详细信息

关键词： Converse theorems generic cuspidal representations even special orthogonal groups

Pharmacological interventions targeting the microcirculation following traumatic spinal cord injury

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Neural Regeneration Research 2024年第1期19卷 35-42页

作者： Rongrong Wang Jinzhu bai department of Spine and Spinal Cord Surgery Beijing Bo’ai HospitalChina Rehabilitation Research CenterBeijingChina School of Rehabilitation Medicine Capital Medical UniversityBeijingChina

Traumatic spinal cord injury is a devastating disorder chara cterized by sensory,motor,and autonomic dysfunction that seve rely compromises an individual's ability to perform activities of daily *** adve rse outcomes are closely related to the complex mechanism of spinal cord injury,the limited regenerative capacity of central neurons,and the inhibitory environment fo rmed by traumatic *** to the microcirculation is an important pathophysiological mechanism of spinal cord injury.A number of therapeutic agents have been shown to improve the injury environment,mitigate secondary damage,and/or promote regeneration and *** them,the spinal cord microcirculation has become an important target for the treatment of spinal cord *** inte rventions targeting the microcirculation can improve the microenvironment and promote recovery following spinal cord *** drugs target the structure and function of the spinal cord microcirculation and are essential for maintaining the normal function of spinal neuro ns,axons,and glial *** review discusses the pathophysiological role of spinal cord microcirculation in spinal cord injury,including its structure and histopathological ***,it summarizes the progress of drug therapies targeting the spinal cord mic rocirc ulation after spinal cord injury.

关键词： blood-spinal cord barrier drug therapy microcirculation microvascular blood flow neuroprotection pharmacological intervention pharmacotherapy spinal cord injury trauma

Nitrogen availability mediates the effects of roots and mycorrhizal fungi on soil organic carbon decomposition:A meta-analysis

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Pedosphere 2024年第2期34卷 289-296页

作者： Tongshuo bai Yunpeng QIU Shuijin HU Ecosystem Ecology Laboratory College of Resources and Environmental SciencesNanjing Agricultural UniversityNanjing 210095China department of Entomology&Plant Pathology North Carolina State UniversityRaleigh NC 27695USA

Plant roots and their associated mycorrhizal fungi critically mediate the decomposition of soil organic carbon(C),but the general patterns of their impacts over a broad geographical range and the primary mediating factors remain *** on a synthesis of 596 paired observations from both field and greenhouse experiments,we found that living roots and/or mycorrhizal fungi increased organic C decomposition by 30.9%,but low soil nitrogen(N)availability(i.e.,high soil C:N ratio)critically mitigated this promotion *** addition,the positive effects of living roots and/or mycorrhizal fungi on organic C decomposition were higher under herbaceous and leguminous plants than under woody and non-leguminous plants,***,there was no significant difference between arbuscular mycorrhizal fungi and ectomycorrhizal fungi in their effects on organic C ***,roots and/or mycorrhizal fungi significantly enhanced the decomposition of leaf litter but not root *** findings advance our understanding of how roots and their symbiotic fungi modulate soil C dynamics in the rhizosphere or mycorrhizosphere and may help improve predictions of soil global C balance under a changing climate.

关键词： arbuscular mycorrhizal fungi ectomycorrhizal fungi leaf litter leguminous plant mycorhizosphere rhizosphere root litter soil C:N ratio

Stellar Populations of AGN-host Dwarf Galaxies Selected with Different Methods

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Research in Astronomy and Astrophysics 2024年第6期24卷 52-67页

作者： Xiejin Li 赵应和 Jinming bai Yunnan Observatories Chinese Academy of SciencesKunming 650216China university of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Radio Astronomy and Technology Chinese Academy of SciencesBeijing 100101China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China

In this paper we investigate the stellar populations and star formation histories of 2.5 active galactic nucleus(AGN)-host dwarf galaxies,consisting of four samples identified separately with different methods(i.e.,radio,X-ray,mid-IR and variability),utilizing the synthesis code STARLIGHT and spectra from the Sloan Digital Sky Survey Data Release *** results show that the variability sample is the oldest,while the mid-IR sample is the youngest,for which the luminosity at 402.?is dominated(>50%)by the young population(t2.and0.1 dex for the light-and mass-weighted mean stellar age,respectively,for our sample of dwarf galaxies,which has a mean fractional contribution of~16%from the *** addition,we obtain further evidence for a possible suppression of star formation in the host galaxy by the central *** also find that there exists an anticorrelation between the extinction-corrected[O III]luminosity and light-weighted mean stellar age,confirming our previous finding that there is a physical connection between AGN and star-forming activities in AGN-host dwarfs.

关键词： galaxies:dwarf galaxies:active galaxies:stellar content

A unified fractional flow framework for predicting the liquid holdup in two-phase pipe flows

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Petroleum Science 2024年第4期21卷 2614-2624页

作者： Fuqiao bai Yingda Lu Mukul M.Sharma Hildebrand department of Petroleum and Geosystems Engineering The University of Texas at Austin

Two-phase pipe flow occurs frequently in oil & gas industry, nuclear power plants, and CCUS. Reliable calculations of gas void fraction(or liquid holdup) play a central role in two-phase pipe flow models. In this paper we apply the fractional flow theory to multiphase flow in pipes and present a unified modeling framework for predicting the fluid phase volume fractions over a broad range of pipe flow conditions. Compared to existing methods and correlations, this new framework provides a simple,approximate, and efficient way to estimate the phase volume fraction in two-phase pipe flow without invoking flow patterns. Notably, existing correlations for estimating phase volume fraction can be transformed and expressed under this modeling framework. Different fractional flow models are applicable to different flow conditions, and they demonstrate good agreement against experimental data within 5% errors when compared with an experimental database comprising of 2.54 data groups from 14literature sources, covering various pipe geometries, flow patterns, fluid properties and flow *** gas void fraction predicted by the framework developed in this work can be used as inputs to reliably model the hydraulic and thermal behaviors of two-phase pipe flows.

关键词： Pipe fractional flow Liquid holdup Multiphase pipe flow Gas void fraction

Surface reconstruction and structural transformation of twodimensional Ni-Fe MOFs for oxygen evolution in seawater media

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Nano Research 2024年第4期17卷 2429-2437页

作者： Liyuan Xiao Xue bai Jingyi Han Tianmi Tang Siyu Chen Hui Qi Changmin Hou Fuquan bai Zhenlu Wang Jingqi Guan Institute of Physical Chemistry College of ChemistryJilin UniversityChangchun 130021China The Second Hospital of Jilin university Changchun 130021China State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of ChemistryJilin UniversityChangchun 130012China Laboratory of Theoretical and Computational Chemistry Institute of Theoretical ChemistryCollege of ChemistryChangchun 130023China

As a four-electron transfer reaction,oxygen evolution reaction(OER)is limited by large overpotential and slow ***,we in-situ synthesized two-dimensional(2.)Ni-Fe metal-organic framework nanosheets on nickel foam(NixFe-TPA/NF,TPA=terephthalic acid)for oxygen evolution in alkaline and alkaline seawater *** 1 M KOH,Ni3Fe-TPA/NF shows a low overpotential(η10)of 189 mV at 10 mA·cm^(-2. and an ultra-low overpotential of only 2.0 mV at 500 mA·cm^(-2..In alkaline seawater,Ni3Fe-TPA/NF still provides impressive OER performance,with anη10 of 2.5 ***-situ Raman characterization results show that the phase transition occurs during the OER,and Ni3FeOOH with more oxygen vacancies is in-situ formed,reducing the OER energy *** functional theory(DFT)reveals that the synergy between Ni and Fe reduces the energy barrier and accelerates the rate-determining *** addition,the ultra-thin 2. sheet structure and the close combination of Ni3FeOOH and highly conductive NF support ensure the high catalytic OER ***,the surface reconstruction and structural modification strategy can be used to design and prepare high-performance OER electrocatalysts for energy-related applications.

关键词： density functional theory(DFT)calculation Ni3FeOOH oxygen evolution reaction seawater electrolysis surface reconstruction