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CSEE Journal of Power and Energy Systems 2024年第3期10卷 963-973页

作者： Wenjuan du Yang Wang h.F.Wang Tao Zhao Tim Littler College of Electrical Engineering Sichuan UniversityChengduChina School of Electrical Engineering the Queen’s University of BelfastBelfastUK IEEE

The induction generator effect(IGE)and the openloop modal proximity(OLMP)are two different reasons why subsynchronous oscillations(SSOs)in a series-compensated power system(SCPS)may *** IGE attributes the growing SSOs to negative resistance,while the OLMP explains the SSO mechanism from the standpoint of modal *** this paper,we investigate the connections between the IGE and the OLMP through equivalent RLC circuit and open-loop modal *** investigation is conducted for two types of seriescompensated power systems where either a synchronous generator or a DFIG is connected at the sending *** investigation reveals the conditions,in which the IGE and the OLMP may jointly cause the growing SSOs,i.e.,both the IGE and the OLMP can explain why the growing SSOs ***,the investigation indicates that the IGE and the OLMP may be totally irrelevant and lead to growing SSOs *** implies that it is possible that in a SCPS,the growing SSOs are only due to the IGE,and the OLMP is non-existent,and vice ***,when the growing SSOs occurs in a SCPS,examination based on both the IGE and the OLMP should be carefully conducted in order to find if the oscillatory instability is due to the IGE,or the OLMP,or both of them.

关键词： Induction generator effect open-loop modal proximity series compensation sub-synchronous oscillations

A Lookahead Read Cache： Improving Read Performance for Deduplication Backup Storage

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Journal of Computer Science & Technology 2017年第1期32卷 26-40页

作者： Dongchul Park Ziqi Fan Young Jin Nam David h. C. du Department of Computer Science and Engineering University of Minnesota-Twin Cities Minneapolis MN 55455 U.S.A.

Data deduplication （dedupe for short） is a special data compression technique. It has been widely adopted to save backup time as well as storage space, particularly in backup storage systems. Therefore, most dedupe research has primarily focused on improving dedupe write performance. however, backup storage dedupe read performance is also a crucial problem for storage recovery. This paper designs a new dedupe storage read cache for backup applications that improves read performance by exploiting a special characteristic： the read sequence is the same as the write sequence. Consequently, for better cache utilization, by looking ahead for future references within a moving window, it evicts victims from the cache having the smallest future access. Moreover~ to further improve read cache performance. it maintains a small log buffer to judiciously cache future access data chunks. Extensive experiments with real-world backup workloads demonstrate that the proposed read cache scheme improves read performance by up to 64.3%

关键词： deduplication dedupe read cache backup

Membrane-based treatment of shale oil and gas wastewater:The current state of knowledge

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Frontiers of Environmental Science & Engineering 2019年第4期13卷 5-21页

作者： Tiezheng Tong Kenneth h. Carlson Cristian A. Robbins Zuoyou Zhang Xuewei du Department of Civil and Environmental Engineering Colorado State UniversityFort CollinsCO 80523USA

Shale oil and gas exploitation not only consumes substantial amounts of freshwater but also generates large quantities of hazardous wastewater. Tremendous research efforts have been invested in developing membrane-based technologies for the treatment of shale oil and gas wastewater. Despite their success at the laboratory scale, membrane processes have not been implemented at full scale in the oil and gas fields. In this article, we analyze the growing demands of wastewater treatment in shale oil and gas production, and then critically review the current stage of membrane technologies applied to the treatment of shale oil and gas wastewater. We focus on the unique niche of those technologies due to their advantages and limitations, and use mechanical vapor compression as the benchmark for comparison. We also highlight the importance of pretreatment as a key component of integrated treatment trains, in order to improve the performance of downstream membrane processes and water product quality. We emphasize the lack of sufficient efforts to scale up existing membrane technologies, and suggest that a stronger collaboration between academia and industry is of paramount importance to translate membrane technologies developed in the laboratory to the practical applications by the shale oil and gas industry.

关键词： Shale oil and gas production Wastewater treatment and reuse Membrane technology Pretreatment Academia-industry collaboration

Nitrogen Contents on Tribological Properties of Magnetron Sputtered SICN Coatings

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材料热处理学报 2004年第05B期25卷 854-857页

作者： TIETUNSUN Y.Q.FU J.WEI h.J.du Departmentofphysics ShanghaiJiaotongUniversityShanghaiChina／／SchoolofMechanicalandProductionEngineeringNanyangTechnologicalUniversitySingapore639798 SchoolofMechanicalandProductionEngineering NanyangTechnologicalUniversitySingapore639798／／SingaporeInstituteofManufacturingTechnologySingapore71NanyangDriveSingapore638075 SingaporeInstituteofManufacturingTechnology -Singapore71NanyangDrivesingapore638075

Silicon carbonitride (SiCN) coatings were deposited on silicon and tungsten carbide substrates by co-sputtering silicon and carbon in argon and nitrogen mixture atmosphere using magnetron-sputtering system. The effect of the N2 concentration, RF substrate bias voltage and target current on film deposition rate, roughness, adhesion, mechanical and tribological properties of coatings were investigated. The deposition rate was found to increase with the increasing nitrogen concentration. X-ray photoelectron spectroscopy analysis showed that high nitrogen concentration in the nitrogen-argon gas mixture enhanced the incorporation of C and N but reduced the incorporation of Si. SiCN coatings have good tribological properties at a N2 concentration of approximately 60%.

关键词： SiCN涂层磁控管溅射含氮量硬度磨损

Spalling characteristics of high-temperature treated granitic rock at different strain rates

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1280-1288页

作者： L.F.Fan Q.h.Yang X.L.du The Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing100124China

The dynamic spalling characteristics of rock are important for stability analysis in rock *** paper presented an experimental investigation on the dynamic spalling characteristics of granite with different temperatures and strain rates.A series of dynamic spalling tests with different impact velocities were conducted on thermally treated granite at different *** dynamic spalling strengths of granite with different temperatures and strain rates were determined.A model was proposed to correlate the dynamic spalling strength of granite,high temperature and strain *** results show that the spalling strength of granite decreases with increasing ***,the spalling strength of granite with a higher strain rate is larger than that with a lower strain *** proposed model can describe the relationship among dynamic spalling strength of granite,high temperature and strain rate.

关键词： Dynamic spalling characteristics high temperature Strain rate Dynamic loading Granite

The microstructure evolution and tensile properties of medium-Mn steel heat-treated by a two-step annealing process

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Journal of Materials Science & Technology 2021年第16期75卷 205-215页

作者： D.P.Yang P.J.du D.Wu h.L.Yi State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819China

The martensitic hot-rolled 0.3 C-6 Mn-1.5 Si(wt%)steel was annealed at 630℃for 24 h to improve its cold rollability,followed by cold rolling and annealing at 670℃for 10 *** annealing process was designed based on the capacities of industrial batch annealing and continuous annealing lines.A duplex submicron austenite and ferrite microstructure and excellent tensile properties were obtained finally,proved the above process is feasible."Austenite memory"was found in the hot-rolled and annealed sample which restricted recrystallization of lath martensite,leading to lath-shaped morphology of austenite and ferrite grains."Austenite memory"disappeared in the cold-rolled and annealed sample due to austenite random nucleation and ferrite recrystallization,resulting in globular microstructure and refinement of both austenite and ferrite *** austenite to martensite transformation contributed most of strain hardening during deformation and improved the uniform elongation,but the dislocation strengthening played a decisive role on the yielding *** tensile curves change from continuous to discontinuous yielding as the increase of cold-rolled reduction due to the weakening dislocation strengthening of austenite and ferrite grains related to the morphology change and grain refinement.A method by controlling the cold-rolled reduction is proposed to avoid the Lüders strain.

关键词： Medium-Mn steel Intercritical annealing Austenite memory Yielding behavior TRIP effect

Small-signal Angular Stability of Power System as Affected by Grid-connected Variable Speed Wind Generators—A Survey of Recent Representative Works

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CSEE Journal of Power and Energy Systems 2017年第3期3卷 223-231页

作者： Wenjuan du Jingtian Bi h.F.Wang State Key Laboratory of Alternate Electric Power Systems(SKLAEPS)with New Energy Resources North China Electric Power UniversityBeijing 102206China

This paper reviews the status and progress of the investigation on power system small-signal angular stability as affected by grid-connected variable speed wind generators(VSWGs).The review is carried out on the basis of a survey of recently published representative *** of the investigation made in those selected papers are classified into two groups:1)VSWGs displacing synchronous generators(SGs);2)VSWGs simply being added in a power *** diversification of the results of the investigation is highlighted in the *** analysis on two strategies of the investigation is conducted in this *** is revealed that in the strategy of VSWGs displacing SGs,there are two factors which could affect power system small-signal angular stability differently:1)Withdrawing the SGs’dynamics;2)adding the VSWGs’*** the strategy of adding VSWGs in the power system,there are also two affecting factors:1)Change of load flow brought about by the VSWGs;2)dynamic interactions with the SGs introduced by the *** diversified results of the investigation obtained so far are not only due to the dependence of the investigation on sample power systems used,but also caused by the mixture of different affecting *** paper is concluded with a summary of key issues of the investigation for future work.

关键词： Electromechanical oscillation modes power system dynamics power system low-frequency oscillation power system small-signal angular stability synchronous generators(SGs) variable speed wind generators(VSWGs)

Evaluation of E-sail parameters on central spacecraft attitude stability using a high-fidelity rigid–flexible coupling model

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Astrodynamics 2024年第2期8卷 271-284页

作者： Chonggang du Zheng h.Zhu Changqing Wang Aijun Li Tuanjie Li School of Electro-Mechanical Engineering Xidian UniversityXi’an 710071China Department of Mechanical Engineering York University4700 Keele StreetTorontoOntario M3J 1P3Canada School of Automation Northwestern Polytechnical UniversityXi’an 710129China

This study examines the impact of electric solar wind sail(E-sail)parameters on the attitude stability of E-sail’s central spacecraft by using a comprehensive rigid–flexible coupling dynamic *** this model,the nodal position finite element method is used to model the elastic deformation of the tethers through interconnected two-node tensile *** attitude dynamics of the central spacecraft is described using a natural coordinate *** rigid–flexible coupling between the central spacecraft and its flexible tethers is established using Lagrange *** research reveals the significant influences of parameters such as tether numbers,tether’s electric potential,and solar wind velocity on attitude ***,solar wind fluctuations and the distribution of electric potential on the main tethers considerably affect the attitude stability of the *** consistent management,the angular velocities of the spacecraft must remain at target ***,the attitude stability of a spacecraft has a pronounced dependence on the geometrical configuration of the E-sail,with axisymmetric E-sails proving to be more stable.

关键词： electric solar wind sail(E-sail) space tether nodal position finite element method(NPFEM) natural coordinate formulation (NCF) attitude stability

how will our knowledge of short gamma-ray bursts affect the distance measurement of binary neutron stars?

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Science China(Physics,Mechanics & Astronomy) 2022年第1期65卷 103-118页

作者： Minghui du Lixin Xu Institute of Theoretical Physics School of PhysicsDalian University of TechnologyDalian 116024China

Gravitational waves from binary neutron stars associated with short gamma-ray bursts have drawn considerable attention due to their prospect in *** such events,the sky locations of sources can be pinpointed with techniques such as identifying the host ***,the cosmological applications of these events still suffer from the problem of degeneracy between luminosity distance and inclination *** address this issue,a technique was proposed in previous study,i.e.,using the collimation property of short gamma-ray *** on the observations,we assume that the cosine of inclination follows a Gaussian distribution,which may act as a prior in the Bayes analysis to break the *** paper investigates the effects of different Gaussian priors and detector configurations on distance measurement and cosmological *** first derive a simplified Fisher information matrix for demonstration,and then conduct quantitative analyses via *** varying the number of third-generation detectors and the scale of prior,we generate four catalogs of 1000 *** is shown that,in the same detecting period,a network of detectors can recognize more and farther events than a single ***,adopting tighter prior and employing multiple detectors both decrease the error of luminosity *** considered is the performance of a widely adopted formula in the error budget,which turns out to be a conservative choice in each *** for cosmological applications,for theΛCDM model,500,200,600,and 300 events are required for the four configurations to achieve 1%h;*** all 1000 events in each catalog,h;and?;can be constrained to(0.66%,0.37%,0.76%,0.49%),and(0.010,0.006,0.013,0.010),*** results of the Gaussian process also show that the gravitational wave standard siren can serve as a probe of cosmology at high redshifts.

关键词： gravitational wave binary neutron star short gamma-ray burst cosmology

Ni nanoparticles confined by yolk-shell structure of CNT-mesoporous carbon for electrocatalytic conversion of CO_(2): Switching CO to formate

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Journal of Energy Chemistry 2022年第7期31卷 224-229,I0006页

作者： Juan du Aibing Chen College of Chemical and Pharmaceutical Engineering Hebei University of Science and TechnologyShijiazhuang 050018HebeiChina

Electrochemical reduction of CO_(2)(CO_(2)ER) to formate has been a promising route to produce value-added *** low-cost and efficient electrocatalysts with high product selectivity is still a grand ***,a novel Ni nanoparticles-anchored CNT coated by mesoporous carbon with yolk-shell structure (CNT/Ni@mC) catalysis was designed for CO_(2)*** nanoparticles were confined in the cavity between CNT and mesoporous carbon shell and the confined space can be controlled by tuning the amount of silica *** mesoporous carbon shell and confined space are beneficial to charge transmission during CO_(2)*** contrast to previous studies,the CNT/Ni@mC catalyst presents selectivity toward formate rather than *** in situ attenuated total reflection Fourier transform infrared spectroscopy measurements indicate the presence of a COO* intermediate that converts to formate under CO_(2)ER *** well-defined structural feature of the confined space of the Ni-based catalyst for selective CO_(2)ER to formate may facilitate in-depth mechanistic understandings on structural factors that affect CO_(2)ER performance.

关键词： Carbon dioxide electrochemical reduction Nickel-based catalyst Formate Yolk-shell CNT