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An uncertainty investigation for liner impedance eduction methods

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Chinese Journal of Aeronautics 2024年第3期37卷 49-59页

作者： Weihao SHI Xiaodong jing School of Energy and Power Engineering Beihang UniversityBeijing 100191China

Impedance eduction methods have been developed for decades to meet the increasing need for high-quality impedance data in the design and optimization of acoustic *** this end,it is important to fully investigate the uncertainty problem,to which only limited attention has been devoted so *** paper considers the possibility of acoustically-induced structural vibration as a nonnegligible uncertainty or error source in impedance eduction *** the frequency moves away from the resonant frequency,with the increase in the value of cavity reactance,the acoustic particle velocity inside liner orifices possibly decreases to the extent comparable to the vibration velocity of liner facing ***,the acoustically-induced vibration,although generally being weak except at the inherent structural frequencies,may considerably affect the impedance eduction results near the anti-resonant frequency where the liner has poor *** demonstrate the effect of structural vibration,the vibration velocity of liner facing sheet is estimated from the experimentally educed admittance of the liner samples whose orifices are sealed with ***,a three-dimensional numerical model is set up,in which normal particle velocity is introduced over the solid portion of liner facing sheet to imitate structural vibration,rather than directly solving the acoustic-structural coupling *** shown by the results,the vibration of liner facing sheet,whose velocity is as small as estimated by the experiment,can result in anomalous deviation of the educed impedance from the impedance model near the anti-resonant *** trend that the anomalous deviation varies with frequency is numerically captured.

关键词： Impedance eduction Uncertainty analysis Acoustically-induced structural vibration Anti-resonant frequency Perforated liner

A review on numerical studies of airflow dynamics and particle deposition in human respiratory system Author links open overlay panel

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Particuology 2024年第8期91卷 351-377页

作者： Hao jing Xinguang Cui School of Aerospace Engineering Huazhong University of Science and TechnologyWuhan430074China

Accurate assessment and prediction of airflow dynamics and particle deposition in the human respiratory tract are essential for human health,involving inhaled drugs for treating various diseases and toxic particles that can cause *** intricate process involves complex multiphase flow with distinct respiratory *** fluid dynamics(CFD)acts as a bridge,overcoming the limitations of in vivo and in vitro experiments and providing a means to fully comprehend and reveal the fundamental mechanisms of respiratory flow and particle behavior on a microscopic *** paper provides a comprehensive overview and concise summary of recent advancements in the numerical simulation of airflow and particle deposition in the human respiratory ***,it summarizes the transition of respiratory tract models from segmented models to emerging physiological characteristic models and whole-lung airway models,and the latest developments on the effects of key factors such as geometric variations,respiratory patterns,and particle physical/chemical properties on respiratory flow and particle deposition.A notable focus of this review is on emerging physiological characteristics models and their associated complex airflow and particle dynamics inside *** paper concludes with recommendations for future research to further advance the development of this field.

关键词： Airflow dynamics Particle deposition Human respiratory system Numerical modeling

Robust adaptive radar beamforming based on iterative training sample selection using kurtosis of generalized inner product statistics

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Journal of Systems Engineering and Electronics 2024年第1期35卷 24-30页

作者： TIAN jing ZHANG Wei School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China National Key Laboratory of Electromagnetic Space Security Chengdu 610036China

In engineering application,there is only one adaptive weights estimated by most of traditional early warning radars for adaptive interference suppression in a pulse reputation interval(PRI).Therefore,if the training samples used to calculate the weight vector does not contain the jamming,then the jamming cannot be removed by adaptive spatial *** the weight vector is constantly updated in the range dimension,the training data may contain target echo signals,resulting in signal cancellation *** cope with the situation that the training samples are contaminated by target signal,an iterative training sample selection method based on non-homogeneous detector(NHD)is proposed in this paper for updating the weight vector in entire range *** principle is presented,and the validity is proven by simulation results.

关键词： adaptive radar beamforming training sample selection non-homogeneous detector electronic jamming jamming suppression

RELATION BETWEEN THE SEEPAGE SEDIMENTATION MECHANISM OF SOIL IN MINING AREA AND SHAFT RUPTURE

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RELATION BETWEEN THE SEEPAGE SEDIMENTATION MECHANISM OF SOIL...

Study of deep transportation and plugging performance of deformable gel particles in porous media

第七届国际地面沉降学术研讨会

作者： jing laiwang~(1 2 3) Lu Jun~4 1 Anhui University of Science and Technology Huainan 232001 China 2 Department of Civil Engineering China University of Mining and Technology Beijing 100083 China 3 College of Civil Engineering & Architecture China University of Mining & Technology(Beijing) Beijing 100083 China 4 Huainan Municipal engineering Ltd. Huainan 232001 China

＜正＞In this paper,the simulation experiment of ground water seepage and soil sedimentation is *** seepage sedimentation mechanism of soil is *** no compression zone in soil around shaft is found. The formation reason and variable laws of slide negative friction are *** on the analysis of a lot of the fracture shafts in China,the relation between ground water seepage and shaft rupture is investigated. The results show that the time of shaft rupture can be established by analyzing the lever of groundwater around *** examples are provided to verify the theory in present paper.

关键词： seepage sedimentation rupture mechanism shaft shaft rupture rupture forecast measures preventing rupture

来源： cnki会议评论

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Petroleum Science 2024年第2期21卷 962-973页

作者： Wen-jing Zhao jing Wang Zhong-Yang Qi Hui-Qing Liu National Key Laboratory of Petroleum Resources and Engineering China University of PetroleumBeijing102249China MOE Key Laboratory of Petroleum Engineering China University of PetroleumBeijing102249China

Deformable gel particles(DGPs) possess the capability of deep profile control and flooding. However, the deep migration behavior and plugging mechanism along their path remain unclear. Breakage, an inevitable phenomenon during particle migration, significantly impacts the deep plugging effect. Due to the complexity of the process, few studies have been conducted on this subject. In this paper, we conducted DGP flow experiments using a physical model of a multi-point sandpack under various injection rates and particle sizes. Particle size and concentration tests were performed at each measurement point to investigate the transportation behavior of particles in the deep part of the reservoir. The residual resistance coefficient and concentration changes along the porous media were combined to analyze the plugging performance of DGPs. Furthermore, the particle breakage along their path was revealed by analyzing the changes in particle size along the way. A mathematical model of breakage and concentration changes along the path was established. The results showed that the passage after breakage is a significant migration behavior of particles in porous media. The particles were reduced to less than half of their initial size at the front of the porous media. Breakage is an essential reason for the continuous decreases in particle concentration, size, and residual resistance coefficient. However, the particles can remain in porous media after breakage and play a significant role in deep plugging. Higher injection rates or larger particle sizes resulted in faster breakage along the injection direction, higher degrees of breakage, and faster decreases in residual resistance coefficient along the path. These conditions also led to a weaker deep plugging ability. Smaller particles were more evenly retained along the path, but more particles flowed out of the porous media, resulting in a poor deep plugging effect. The particle size is a function of particle size before inject

关键词： Physical simulation Deformable gel particle Breakage Particle size Residual resistance coefficient

Gravitational wave fluxes on generic orbits in near-extreme Kerr spacetime:Higher spin and large eccentricity

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 16-28页

作者： Changkai Chen Jiliang jing Department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of EducationSynergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangsha 410081China

To accurately obtain the waveform template of gravitational waves, substantial computational resources and extremely high precision are often required. In a previous study, we employed the confluent Heun function to obtain an exact solution to the Teukolsky equation. This approach allowed us to efficiently and accurately calculate the gravitational wave flux for a particle in circular orbits around a Schwarzschild black hole. Building on this method, we now extend its application to calculate the asymptotic gravitational wave fluxes from a particle in generic orbits around a near-extreme Kerr black hole. Our extended method proves particularly effective in handling computational challenges associated with large eccentricities(e = 0.9), higher spins(a = 0.999), higher harmonic modes, and strong-field regions. The results we obtained significantly outperform those derived from the numerical integration method based on the Mano-Suzuki-Takasugi method.

关键词： gravitational wave fluxes exact solution Teukolsky equation near-extreme Kerr black hole

Transition metal clusters with precise numbers of atoms anchored on graphdiyne as multifunctional electrocatalysts for OER/ORR/HER:a computational study

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Rare Metals 2024年第7期43卷 3107-3117页

作者： Xin-Yang Liu jing-Wei Liu Gang Li jing-Xiang Zhao College of Chemistry and Chemical Engineering Harbin Normal UniversityHarbin 150025China

Subnanometer metal clusters play an increasingly important role in heterogeneous catalysis due to their high catalytic activity and *** this work,by means of the density functional theory(DFT) calculations,the catalytic activities of transition metal clusters with precise numbers of atoms supported on graphdiyne(TM_(1-4)@GDY,TM=V,Cr,Mn,Fe,Co,Ni,Cu,Ru,Rh,Pd,Ir,Pt) were investigated for oxygen evolution reactions(OER),oxygen reduction reactions(ORR) and hydrogen evolution reactions(HER).The computed results reveal that the Pd_(2),Pd_(4) and Pt_(1) anchored graphdiyne can serve as trifunctional catalysts for OER/ORR/HER with the overpotentials of 0.49/0.37/0.06,0.45/0.33/0.12 and 0.37/0.43/0.01 V,respectively,while Pd_(1) and Pt_(2)@graphdiyne can exhibit excellent catalytic performance for water splitting(OER/HER) with the overpotentials of 0.55/0.17 and 0.43/0.03 *** addition,Ni_(1) and Pd_(3) anchored GDY can perform as bifunctional catalysts for metal-air cells(OER/ORR) and fuels cells(ORR/HER) with the overpotentials of 0.34/0.32 and 0.42/0.04 V,***,by precisely controlling the numbers of atoms in clusters,the TM_(1-4) anchored graphdiyne can serve as promising multifunctional electrocatalysts for OER/ORR/HER,which may provide an instructive strategy to design catalysts for the energy conversation and storage devices.

关键词： Density functional theory Graphdiyne Single-cluster catalysts Multifunctional electrocatalysts Overpotential

Challenges and prospects for room temperature solid-state sodiumsulfur batteries

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Nano Research 2024年第3期17卷 1402-1426页

作者： Yashuang Qiu jing Xu Research Center of Grid Energy Storage and Battery Application School of Electrical and Information EngineeringZhengzhou UniversityZhengzhou 450001China

Room temperature sodium-sulfur(Na-S)batteries,known for their high energy density and low cost,are one of the most promising next-generation energy storage ***,the polysulfide shuttling and uncontrollable Na dendrite growth as well as safety issues caused by the use of organic liquid electrolytes in Na-S cells,have severely hindered their ***-state electrolytes instead of liquid electrolytes are considered to be the most direct and effective solution to solve the above ***,its practical application is still greatly challenged due to the poor interfacial compatibility between the all-solid-state electrolytes and the anode/cathode,ionic conductivity,and the shuttle effect caused by the presence of liquid phase in the quasi-solid-state *** paper presents a comprehensive review of solid-state Na-S batteries from the perspective of regulating interfacial compatibility and improving ionic conductivity as well as suppressing polysulfide *** to different components,solid-state electrolytes were divided into five categories:solid inorganic electrolytes,solid polymer electrolytes,polymer/inorganic solid hybrid electrolytes,gel polymer electrolytes,and liquid–solid inorganic hybrid ***,the prospect of developing high performance solid-state electrolytes to improve the cycling stability of room temperature Na-S cells is envisaged.

关键词： sodium-sulfur batteries solid-state electrolytes ionic conductivity polysulfide shuttling interfacial compatibility

Boosting electrocatalytic nitrate reduction to ammonia via Cu_(2)O/Cu(OH)_(2)heterostructures promoting electron transfer

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Nano Research 2024年第6期17卷 4898-4907页

作者： jing Geng Sihan Ji Anhui Province International Research Center on Advanced Building Materials School of Materials Science and Chemical EngineeringAnhui Jianzhu UniversityHefei 230601China Anhui Province Key Laboratory of Advanced Building Materials Anhui Jianzhu UniversityHefei 230601China School of Energy Materials and Chemical Engineering Hefei UniversityHefei 230601China

Electrocatalytic nitrate(NO_(3)^(−))reduction to ammonia(NH_(3))offers a viable approach for sustainable NH_(3)production and environmental ***(Cu)possesses a distinctive electronic structure,which can augment the reaction kinetics of NO_(3)^(−)and impede hydrogen evolution reaction(HER),rendering it a promising contender for the electrosynthesis of NH_(3)from NO_(3)^(−).Nevertheless,the role of Cu_(2)O in copper-based catalysts still requires further investigation for a more comprehensive ***,the Cu_(2)O/Cu(OH)_(2)heterostructures are successfully fabricated through liquid laser irradiation using CuO nanoparticles as a *** and theoretical researches reveal that Cu_(2)O/Cu(OH)_(2)heterostructure exhibits enhanced electrocatalytic performance for NO_(3)^(−)to NH_(3)because Cu(OH)_(2)promotes electron transfer and reduces the valence state of Cu active site in Cu_(2)***−0.6 V(*** hydrogen electrode(RHE)),the NH_(3)yield reaches its maximum at 1630.66±29.72μg·h^(−1)·mgcat^(−1),while the maximum of Faraday efficiency(FE)is 76.95%±5.51%.This study expands the technical scope of copper-based catalyst preparation and enhances the understanding of the electrocatalytic mechanism of NO_(3)^(−)to NH_(3).

关键词： Cu_(2)O/Cu(OH)_(2)heterostructures electron transfer ammonia synthesis electrocatalysts nitrate