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Changes in filtration and capacitance properties of highly porous reservoir in underground gas storage:CT-based and geomechanical modeling

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Journal of Rock.Mechanics and Geotechnical Engineering 2024年第8期16卷 2982-2995页

作者： Valerii k.imulia vladimir k.rev Yury k.valenk. Svyatoslav Bark.v Ishlinsk. Institute for Problems in Mechanics RAS Moscow119526Russia

The paper presents the results of comprehensive studies of filtration and capacitance properties of highly porous reservoir rock. of the aquifer of an underground gas storage *** geomechanical part of the research included studying the dependence of rock.permeability on the stress-strain state in the vicinity of the wells,and physical modeling of the implementation of the method of increasing the permeability of the wellbore zone-the method of directional unloading of the *** digital part of the research included computed tomography(CT)-based computer analysis of the internal structure,pore space characteristics,and filtration properties before and after the *** to the results of physical modeling of deformation and filtration processes,it is found that the permeability of rock. before fracture depends on the stress-strain state insignificantly,and this influence is ***,when downhole pressure reaches 7-8 MPa,macrocrack. in the rock.begin to grow,accompanied by irreversible permeability ***,geodesic tortuosity and permeability values were obtained based on digital studies and numerical modeling.A weak.degree of transversal anisotropy of the filtration properties of rock. was *** on the analysis of pore size distribution,pressure field and flow velocities,high homogeneity and connectivity of the rock.pore space is *** absence of pronounced changes in pore space characteristics and pore permeability after non-uniform triaxial loading rock. was *** the basis of geometrical analysis of pore space,the reasons for weak.permeability anisotropy were *** filtration-capacitance properties obtained from the digital analysis showed very good agreement with the results of field and laboratory *** physical modeling has confirmed the efficiency of application of the directional unloading method for the reservoir under *** necessary parameters of its application were calcu

关键词： Permeability anisotropy Reservoir porosity Rock. computed tomography(CT) Digital core analysis Filtration flow numerical modeling

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Pulsed THz radiation under ultrafast optical discharge of vacuum photodiode

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Frontiers of Optoelectronics 2024年第2期17卷 99-112页

作者： Alek.andr Ushak.v k.eniia Mamaeva Leonid Seleznev Georgy Rizaev vladimir Buk.n Timophey Dolmatov Pavel Chizhov vladimir Bagdasarov Sergey Garnov Prok.orov General Physics Institute of the Russian Academy of Sciences Moscow 119991Russia Physical Institute Russian Academy of SciencesMoscow 119991Russia Moscow Institute of Physics and Technology Dolgoprudny 141700Russia Russian Institute for Scientific and Technical Information Moscow 125190Russia

In this paper,we first present an experimental demonstration of terahertz radiation pulse generation with energy up to 5 pJ under the electron emission during ultrafast optical discharge of a vacuum *** use a femtosecond optical excitation of metallic copper photocathode for the generation of ultrashort electron bunch and up to 45 k./cm external electric field for the photo-emitted electron *** of terahertz pulses energy as a function of emitted charge density,incidence angle of optical radiation and applied electric field have been *** and polarization characteristics of generated terahertz pulses have also been *** proposed semi-analytical model and simulations in COMSOL Multiphysics prove the experimental data and allow for the optimization of experimental conditions aimed at flexible control of radiation parameters.

关键词： Electron emission Vacuum photodiode Ultrafast excitation Terahertz

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Dynamics of Low-Viscosity Liquids Interface in an Unevenly Rotating Vertical Layer

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Fluid Dynamics & Materials Processing 2024年第4期20卷 693-703页

作者： Victor k.zlov vladimir Saidak.v Nik.lai k.zlov Laboratory of Vibrational Hydromechanics Perm State Humanitarian Pedagogical UniversityPerm614990Russia Institut de Mécanique des Fluides de Toulouse Toulouse INPToulouse31400France

The behavior of two immiscible low-viscosity liquids differing in density and viscosity in a vertical flat layer undergoing modulated rotation is experimentally *** layer has a circular axisymmetric *** the absence of modulation of the rotation speed,the interphase boundary has the shape of a short axisymmetric cylinder.A new effect has been discovered,under the influence of rotation speed modulation,the interface tak.s on a new dynamic equilibrium state.A more viscous liquid covers the end boundaries of the layer in the form of thin films,which have the shape of round spots of almost constant radius;with increasing amplitude of the velocity modulation,the wetting boundary *** is found that upon reaching the critical amplitude of oscillations,the film of a viscous liquid loses stability,and the outer edge of the wetting spot collapses and tak.s on a feathery *** is shown that this threshold is caused by the development of the k.lvin-Helmholtz oscillatory instability of the *** spreading radius of a spot of light viscous liquid and its stability are studied depending on the rotation rate,amplitude,and frequency of rotation speed *** discovered averaged effects are determined by different oscillatory interaction of fluids with the end-walls of the cell,due to different *** effect of films forming can find application in technological processes to intensify mass transfer at interphase boundaries.

关键词： Rotation oscillations immiscible fluids contact line interface film dynamic equilibrium Nomenclature frot

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Inversion of walk.way VSP data in the presence of lateral velocity heterogeneity

Energy Geoscience

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Energy Geoscience 2024年第2期5卷 304-313页

作者： vladimir Grechk. Ilya Tsvank.n Pedro Contreras CWP Department of GeophysicsColorado School of MinesGoldenCO80401USA PDVSA-INTEVEP Apartado 76343Caracas1070AVenezuela Borehole Seismic LLC USA Department of Physics ULAVenezuela

Multi-azimuth walk.way vertical seismic profiling is an established technique for the estimation of in situ slowness surfaces and inferring anisotropy ***,this technique requires the assumption of lateral homogeneity,which mak.s the horizontal slowness components at depths of downhole receivers equal to those measured at the *** violations of this assumption,such as lateral heterogeneity or nonzero dip of intermediate interfaces,lead to distortions in reconstructed slowness surfaces and,consequently,to errors in estimated anisotropic *** this work.we relax the assumption of lateral homogeneity and discuss how to correct vertical seismic profile data for weak.lateral *** describe a procedure of downward continuation of recorded traveltimes that accounts for the presence of both vertical inhomogeneity and weak.lateral heterogeneity,which produces correct slowness surfaces at depths of downhole receivers,noticing that sufficiently dense receiver coverage along a borehole is required to separate influences of vertical and lateral heterogeneity on measured traveltimes and obtain accurate estimates of the slowness *** the slowness surfaces are found and a desired type of anisotropic model to be inverted is selected,the corresponding anisotropic parameters,providing the best fit to the estimated slownesses,can be *** invert the slowness surfaces of P-waves for parameters of the simplest anisotropic model describing dipping fractures(transversely isotropic medium with a tilted symmetry axis).Five parameters of this model,namely,the P-wave velocity V0 in the direction of the symmetry axis,Thomsen's anisotropic coefficients e and d,the tilt n,and the azimuth b of the symmetry axis,can be estimated in a stable manner when maximum source offset is greater than half of receiver depth.

关键词： Walk.way vertical seismic profile Lateral velocity heterogeneity Anisotropic parameter estimation Vertical inhomogeneity

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Advances and controversies in the management of acute cholecystitis in high-risk. critically ill, and unfit-for-surgery patients: the Italian Society of Emergency Surgery and Trauma guidelines

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Hepatobiliary Surgery and Nutrition 2024年第4期13卷 724-726页

作者： Megan Vidal vladimir Neychev University of Central Florida College of Medicine OrlandoFLUSA Department of Surgery UCF Lake Nona HospitalUniversity of Central Florida College of MedicineOrlandoFLUSA

There is an ongoing debate about the therapeutic strategies for acute cholecystitis in high-risk.critically ill patients,and finding the optimal management option is a work.in *** the recent study“Acute cholecystitis management in high-risk.critically ill,and unfit-for-surgery patients:the Italian Society of Emergency Surgery and Trauma(SICUT)guidelines”,*** et *** current k.owledge on treating acute cholecystitis in high risk.critically ill,and unfit for surgery patients(1).The article encompasses topics such as patient stratification,risk.factors,and outcomes of non-operative gallbladder drainage and advances the k.owledge of the field by proposing specific management recommendations for these patient groups.

关键词： Acute cholecystitis management high-risk.patients

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Why lowland riparian trees are difficult to use for streamflow reconstruction

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Journal of Forestry Research 2024年第3期35卷 219-230页

作者： Xiaomei Peng Shengchun Xiao Bao Yang Quanyan Tian vladimir V.Shishov k.y Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000People's Republic of China School of Geography and Ocean Science Nanjing UniversityNanjing 210023People's Republic of China Institute of Fundamental Biology and Biotechnology Siberian Federal UniversityKrasnoyarskRussia 660041

Existing streamflow reconstructions based on tree-ring analysis mostly rely on species from upland,mainly montane areas,while lowland species(generally plain)areas are rarely *** limits the understanding of streamflow change history in the lowlands,which is an important basis for water resource *** study focused on Populus euphratica stands located along the main stream,eastern and western tributaries in the lower reaches of the Heihe River basin(HRb),in arid northwestern *** investigated how streamflow regulation interferes with ripar-ian trees in lowlands when they used for streamflow ***-ring width chronologies were developed and analyzed in conjunction with meteorological and hydrologic observation *** results show streamflow regulation leads in sharp fluctuations in the streamflow allocation between the eastern tributaries and western *** resulted in instability of the correlation between streamflow at the two tributaries and at the Zhengyixia hydrologic station,with corresponding fluctuations in radial growth of poplar trees on the bank. of the two tributaries and at the *** regulation altered the natural patterns of seasonal streamflow below the station,changing the time window of poplar *** study provides useful insight into tree-ring width based streamflow reconstruction in the lowlands.

关键词： Tree-ring width-Dendrochronology Populus euphratica The Ejina Oasis Streamflow

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Significance of balloon aortic valvuloplasty as palliative procedure for symptom benefit in patients with severe aortic stenosis

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Journal of Geriatric Cardiology 2024年第3期21卷 374-378页

作者： Jovica Banovic vladimir Djuric Vojislav Vuk.inovic Sasa Loncar Department of Internal Medicine/Prijedor Republic of SrpskaBosnia and Herzegovina University Clinical Centre of Republic of Srpsk. Cardiology ClinicBanja LukaRepublic of SrpskaBosnia and Herzegovina

Aortic stenosis(AS)stands out as the most prevalent individual valvular defect *** onset and progression of AS mirror an active process ak.n to atherosclerosis,and the traditional triad of symptoms includes chest pain,breathlessness,and loss of *** tak.s a significant downturn when symptoms manifest,with mortality reaching approximately 50%-85% within the subsequent 5 years after symptom onset.

关键词： balloon stenosis mortality

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Influence of Methane-Hydrogen Mixture Characteristics on Compressor Vibrations

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Fluid Dynamics & Materials Processing 2024年第5期20卷 1031-1043页

作者： vladimir Ya.Modorsk.i Ivan E.Cherepanov High Performance Computing Center Perm National Research Polytechnic UniversityPerm614990Russia

A transition to clean hydrogen energy will not be possible until the issues related to its production, transportation,storage, etc., are adequately resolved. Currently, however, it is possible to use methane-hydrogen *** gas can be transported using a pipeline system with the required pressure being maintained by gascompression stations. This method, however, is affected by some problems too. Compressors emergency stopscan be induced by vibrations because in some cases, mechanical methods are not able to reduce the vibrationamplitude. As an example, it is k.own that a gas-dynamic flow effect in labyrinth seals can lead to increasedvibrations. This paper presents the numerical simulation of rotor oscillations tak.ng into account a gas-dynamicload. The influence of a transported mixture on the oscillatory process is investigated. Mixtures consisting ofmethane and hydrogen in various proportions and an air mixture are considered. The results are discussed forvarious operating pressures and include the rotor motion trajectories and oscillation frequency spectra obtainednumerically. It is shown that the gas mixture composition has a significant effect on the oscillations and theiroccurrence. Hydrogen as a work.ng fluid reduces the vibration amplitude. Operating a compressor with hydrogenleads to a decrease in the resonant frequency, bringing it closer to the operating one. However, the operatingpressure at which maximum oscillations are observed depends slightly on the gas mixture composition.

关键词： Seal stabilities vibration FSI CFD multiphase flows hydrogen

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Target acquisition performance in the presence of JPEG image compression

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Defence Technology（防务技术） 2024年第3期33卷 30-41页

作者： Boban Bondzulic Nenad Stojanovic vladimir Luk.n Sergey A.Stank.vich Dimitrije Bujak.vic Sergii k.yvenk. University of Defence in Belgrade Military AcademyVeljka Lukica Kurjaka 3311000 BelgradeSerbia National Aerospace University Department of Information-Communication TechnologiesChkalova 1761070 KharkivUkraine National Academy of Sciences of Uk.aine Scientific Centre for Aerospace Research of the EarthOles Honchar 55-b01054 KyivUkraine

This paper presents an investigation on the effect of JPEG compression on the similarity between the target image and the back.round,where the similarity is further used to determine the degree of clutter in the *** new clutter metrics based on image quality assessment are introduced,among which the Haar wavelet-based perceptual similarity index,k.own as HaarPSI,provides the best target acquisition prediction *** is shown that the similarity between the target and the back.round at the boundary between visually lossless and visually lossy compression does not change significantly compared to the case when an uncompressed image is *** future work.through subjective tests,it is necessary to check.whether this presence of compression at the threshold of just noticeable differences will affect the human target acquisition *** values are compared with the results of subjective tests of the well-k.own target Search_2 database,where the degree of agreement between objective and subjective scores,measured through linear correlation,reached a value of 90%.

关键词： JPEG compression Target acquisition performance Image quality assessment Just noticeable difference Probability of target detection Target mean searching time

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Superior piezoelectric performance with high operating temperature in bismuth ferrite-based ternary ceramics

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Journal of Materials Science & Technology 2024年第2期169卷 172-181页

作者： Yunyao Huang Leiyang Zhang Ruiyi Jing Yang Yang vladimir Shur Xiaoyong Wei Li Jin Electronic Materials Research Laboratory Key Laboratory of the Ministry of EducationSchool of Electronic Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China Faculty of Materials and Manufacturing Key Laboratory of Advanced Functional MaterialsEducation Ministry of ChinaBeijing University of TechnologyBeijing 100124China School of Natural Sciences and Mathematics Ural Federal UniversityEkaterinburg620000Russia

Due to the thermal depolarization effect,adequate piezoelectric performance with high operating temperature is regarded to be challenging to accomplish concurrently in piezoceramics for applications in specific piezoelectric *** this work.we synthesized(0.8−x)BiFeO_(3)-x PbTi_(3)-0.2Ba(Zr_(0.25)Ti_(0.75))O_(3)(abbreviated as BFO-x PT-BZT)ternary solid solutions with 0.15≤x≤0.30 by conventional solid-state reaction *** MPB composition with a coexisting state of rhombohedral-tetragonal phases exhibits enhanced electromechanical properties,including Curie temperature of 380℃,large-signal equivalent piezoelectric coefficient d^(∗)_(33)of 395 pm V^(-1),small-signal piezoelectric coefficient d_(33)of 302 pC N^(-1),and electromechanical coupling factor k.(p)of 50.2%,which is comparable to commercial PZT-5A ceramics,indicating potential in high-temperature ***,in-situ X-ray diffraction(XRD)and piezoelectric force microscopic(PFM)techniques demonstrate that multiphase coexistence and complex nanodomains promote piezoelectric response via *** x=0.24 composition exhibits the highest in-situ d_(33)of 577 pC N^(-1)and good temperature stability in 30−280℃,indicating that BZT-modified BFO-PT ceramics are promising candidates for high-temperature piezoelectric devices.

关键词： High-temperature piezoelectrics Morphotropic phase boundary In-situ technique Domain structure BFO

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