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Comparison of pulse-modulated and continuous operation modes of a radio-frequency inductive ion source

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Plasma Science and Technology 2023年第2期25卷 131-145页

作者： ilya ZADIRIEV Elena KRALKINA Konstantin VAVILIN Alexander NIKONOV Georgy SHVIDKIY Physical Electronics Department Faculty of PhysicsLomonosov Moscow State UniversityMoscow 119991Russia

The paper describes an experimental study of the characteristics of a pulse-modulated radiofrequency(RF)discharge sustained at low pressures,typical of the operating modes of RF gridded ion *** motivation for the study is the question of whether the RF pulsemodulated mode can increase the efficiency of the ion *** ion current values extracted from an RF inductive ion source operating in continuous and pulse-modulated modes were *** experimental data were also compared with the parameter calculations based on a0D numerical model of the *** measurements showed that the pulse-modulated operation mode of the RF ion source had a noticeable advantage when the power of the RF generator was 140 W or ***,as the generator power increased,the advantage was lost because the pulse-modulated operation mode,having a higher RF power instant value,entered the region of existence sooner than the continuous mode,where the ion production cost begins to grow with RF power.

关键词： discharge plasma radio frequency(RF) pulse electrons ions

Inversion of walkaway VSP data in the presence of lateral velocity heterogeneity

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Energy Geoscience

Energy Geoscience 2024年第2期5卷 304-313页

作者： Vladimir Grechka ilya Tsvankin Pedro Contreras CWP Department of GeophysicsColorado School of MinesGoldenCO80401USA PDVSA-INTEVEP Apartado 76343Caracas1070AVenezuela Borehole Seismic LLC USA Department of Physics ULAVenezuela

Multi-azimuth walkaway 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 makes 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： Walkaway vertical seismic profile Lateral velocity heterogeneity Anisotropic parameter estimation Vertical inhomogeneity

Focused electron beam transport through a long narrow metal tube at elevated pressures in the forevacuum range

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Plasma Science and Technology 2023年第1期25卷 128-134页

作者： ilya BAKEEV Kirill KARPOV Aleksandr KLIMOV Efim OKS Aleksey ZENIN Tomsk State University of Control Systems and Radioelectronics Tomskaâ634050Russia Institute of High Current Electronics Siberian BranchRussian Academy of SciencesTomskaâ634055Russia

We present here our investigations of the features of focused electron beam transport in free space at elevated pressures of a few *** have explored the effect of the beam accelerating voltage,operating gas pressure,and magnetic focusing upon the trajectory of beam electrons in the crossover region,in particular on the beam convergence and divergence *** is shown that for the forevacuum pressure range of 2-5 Pa explored,a distinctive feature of the propagation of a focused electron beam with a current of up to 20 mA at an accelerating voltage of 10-20 kV is the difference in the angles of convergence(before the focus)and divergence(after the focus).Whereas at a low pressure of 2 Pa the divergence angle is smaller than the convergence angle,as the pressure increases the divergence angle increases and for pressures greater than 5 Pa the divergence angle is greater than the convergence *** results obtained were used in experiments on electron beam transport through a long narrow metal tube with a diameter of 5.8-9.2 mm and length of 10-30 *** show that for a 30 cm long tube of 7.5 mm diameter,the focused beam transmission can exceed 70%.

关键词： focused electron beam plasma electron source forevacuum pressure range long metal tube

MixedMultiscale Finite Volume Methods for Elliptic Problems in Two-Phase Flow Simulations

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Communications in Computational Physics 2012年第1期11卷 19-47页

作者： Lijian Jiang ilya D.Mishev Institute for Mathematics and its Applications University of MinnesotaMinneapolisMN 55455USA ExxonMobil Upstream Research Company HoustonTX 77252USA

We develop a framework for constructing mixed multiscale finite volume methods for elliptic equations with multiple scales arising from flows in porous *** of the methods developed using the framework are already known[20];others are *** insight is gained for the known methods and extra flexibility is provided by the new *** give as an example a mixed MsFV on uniform mesh in *** method uses novel multiscale velocity basis functions that are suited for using global information,which is often needed to improve the accuracy of the multiscale simulations in the case of continuum scales with strong non-local *** method efficiently captures the small effects on a coarse *** analyze the new mixed MsFV and apply it to solve two-phase flow equations in heterogeneous porous *** examples demonstrate the accuracy and efficiency of the proposed method for modeling the flows in porous media with non-separable and separable scales.

关键词： Mixedmultiscale finite volume methods elliptic equations two-phase flows heterogeneous porous media

Constrained control of free piston engine generator based on implicit reference governor

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Science China(Information Sciences) 2018年第7期61卷 40-56页

作者： Xun GONG ilya KOLMANOVSKY Emanuele GARONE Kevin ZASECK Hong CHEN State Key Laboratory of Automotive Simulation and Control Jilin University Department of Aerospace Engineering University of Michigan Ecole Polytechnique Universite Libre de Bruxelles

The free piston engine generator(FPEG) is a novel power plant concept for series hybrid electric vehicles(HEV) that requires reliable control to regulate piston motion and guarantee safe operation during load transitions. This paper focuses on the control and constraint enforcement in a FPEG using a reference governor. A discrete, implicit, control oriented model describing the piston motion in a two-stroke twocylinder FPEG at the turnaround point is derived based on energy balance and a feedback controller is designed to track the desired turnaround position by regulating fuel. An implicit reference governor is developed to guarantee safe piston motion by managing the load transitions. The reference governor utilizes Newton’s method applied to an implicit nonlinear model for response prediction and a bisection search algorithm to enforce the constraints for all the future time instants by adjusting the reference ***, the error in applying one iteration of Newton’s method in predicting the response of the implicit nonlinear system is estimated and accounted for in constraint tightening to guarantee that constraints are robustly enforced. The simulation results show that the feedback control scheme incorporating the developed implicit reference governor can effectively enforce the prescribed constraints during load transition.

关键词： free piston engine generator implicit system reference governor Newton’s method error bound

Constrained optimal steady-state control for isolated traffic intersections

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Control Theory and Technology 2014年第1期12卷 84-94页

作者： Jack HADDAD David MAHALEL ilya IOSLOVICH Per-Olof GUTMAN Technion Sustainable Mobility and Robust Transportation (T-SMART) Laboratory Technion - Israel Institute of Technology Haifa 32000 Israel

The steady-state or cyclic control problem for a simplified isolated traffic intersection is considered. The optimization problem for the green-red switching sequence is formulated with the help of a discrete-event max-plus model. Two steady-state control problems are formulated： optimal steady-state with green duration constraints, and optimal steady-state control with lost time. In the case when the criterion is a strictly increasing, linear function of the queue lengths, the steady-state control problems can be solved analytically. The structure of constrained optimal steady-state traffic control is revealed, and the effect of the lost time on the optimal solution is illustrated.

关键词： Steady-state control Discrete-event models Isolated traffic intersections

Sarcoidosis imitating breast cancer metastasis:a case report and literature review

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Cancer Biology & Medicine 2016年第3期13卷 396-398页

作者： Teimuraz Kochoyan Mobil Akhmedov Alexander Shabanov ilya Terekhov Department of Surgery No.2 Department of Pathology Russian Cancer Research CenterMoscow 115478Russia

Sarcoidosis is a benign systematic granulomatous disorder of unknown etiology and is associated with various ***, granulomatous and metastatic lymph node lesions are difficult to distinguish even when using precise and modern diagnostic methods, such as positron emission tomography. Thus, histological verification is the only method that can be used to accurately describe the nature of this disease. In this article, we report a case of non-luminal HER-2/neu-positive breast cancer in a patient without history of sarcoidosis and suspected to have metastatic disease.

关键词： Sarcoidosis breast neoplasms metastasis granulomatous lymph node

Plasma treatment for enhancement of the sorption capacity of carbon fabric

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Plasma Science and Technology 2021年第12期23卷 150-160页

作者： IIya ZADIRIEV Elena KRALKINA Vladimir SAMOILOV Victoria ELCHANINOVA Valentina GORINA ilya IVANENKO Konstantin VAVILIN Alexander NIKONOV Physical Electronics Department Faculty of PhysicsLomonosov Moscow State University119991 MoscowRussia Research Institute for Graphite-Based Structural Materials‘Nllgrafit’ 1524 MoscowRussia

In this work we carried out an experimental investigation into enhancement of the sorption capacity of carbon fabric using plasma treatment *** fabric is based on viscose fiber and is hydrophobic by *** of the fabric sorption capacity is required for its application in *** this purpose,two plasma treatment methods were considered,*** nonequilibrium radiofrequency(RF)discharge and a vacuum RF plasma source with an external magnetic *** treated by atmospheric discharge demonstrated aging effects during the first week after *** sorption capacity of samples treated by the RF plasma source was stable over the same period and reached values as high as *** of the beam created by the vacuum RF plasma source were analyzed and dependences of the fabric sorption capacity and specific surface area on plasma treatment time were *** found that sorption capacity reached its maximum value after 30 min of treatment and did not change significantly if processing was continued,while the specific surface area reached its maximum after 3 min of treatment and quickly decreased after *** was found that the micropore structure of the fabric remained almost the same during plasma *** volume of mesopores in a unit of the fabric mass(specific volume)doubled during the first 5 min of treatment and returned to initial values after 30 min of *** sorption capacity continued to increase even when the specific surface area decreased after reaching its peak *** indicates the important role of surface functional groups formed on carbon fibers during plasma *** is consistent with the results of x-ray photoelectron spectroscopy analysis showing changes in surface oxidation during plasma treatment.

关键词： carbon fabric sorption plasma treatment radiofrequency

A Dataflow-Oriented Programming Interface for Named Data Networking

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Journal of Computer Science & Technology 2018年第1期33卷 158-168页

作者： Li-Jing Wang Yong-Qiang Lv ilya Moiseenko Dong-Sheng Wang Department of Computer Science and Technology Tsinghua University Beijing 100084 China Tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China Computer Science Department University of California Los Angeles CA 90095 U.S.A.

Inheriting from a data-driven communication pattern other than a location-driven pattern, named data net- working （NDN） offers better support to network-layer dataflow. However, the application developers have to handle complex tasks, such as data segmentation, packet verification, and flow control, due to the lack of proper transport-layer protocols over the network layer. In this study, we design a dataflow-oriented programming interface to provide transport strategies for NDN, which greatly improves the efficiency in developing applications. This interface presents two application data unit; （ADU） retrieval strategies according to different data publishing patterns, in which it adopts an adaptive ADU pipelining algorithm to control the dataflow based on the current network status and data generation rate. The interface also offers network measurement strategies to monitor an abundance of critical metrics infuencing the application performance. We verify the functionality and performance of our interface by implementing a video streaming application spanning 11 time zones over the worldwide NDN testbed. Our experiments show that the interface can efficiently support developing high-performance and dataflow-driven NDN applications.

关键词： named data networking (NDN) dataflow network architecture and design transport-layer protocol