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Analytical model of 2D leakoff in waterflood-induced fractures

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第7期15卷 1713-1733页

作者： Igor Reznikov Dimitry Chuprakov Ilmir Bekerov Schlumberger Moscow Research MoscowRussia

Waterflood-induced fractures,also known as self-induced fractures,spontaneously form at injection wells during waterflooding.These fractures propagate long distances through rock,allowing injected fluids to travel far away from a well,both within and outside the flooding layer.Essentially,the me-chanics of waterflood-induced fracture propagation is similar to that of hydraulic fractures,which are intentionally created for reservoir stimulation.Fracturing models developed for hydraulic fractures can also be applied to waterflood-induced fractures.However,waterflood-induced fractures are typically pumped with much larger volumes of water or brine and grow much longer in time.As a result,fluid leakoff from waterflood fractures into the formation is more extensive and two-dimensional(2D),a characteristic that is often ignored in a majority of modern fracturing simulators,making their appli-cation to waterflood fractures unreliable.In this work,we revisit the problem of leakoff for long-growing waterflood-induced fractures and develop a new Analytical model for fluid leakoff that provides improved predictions of fracture geometry and can be easily implemented in fracturing simulators.We incorporate the developed solution into the classical Perkins-Kern-Nordgren(PKN)model of fracture growth,which shows that the choice of the Carter or a 2D leakoff model greatly impacts fracture ge-ometry at large time.The conducted parametric study shows while a toughness-dominated regime af-fects fracture evolution,most of fracture lifetime occurs in a viscosity-and-leakoff-dominated regime.We also develop an asymptotic solution for a leakoff profile in the limiting case of 2D leakoff domination(~~M and~~K).Finally,we study 3D fracture growth and out-of-zone injection with three layers and a complex structure of zones.The study shows that ignoring the 2D leakoff during simulation results in a significant overestimation of fracture geometry predictions.The present work,thus,plays an important role in improving waterflood fracture model

关键词： Waterflooding Leakoff Analytical model Hydraulic fracturing Two-dimensional flow

Analytical model for Underwater Wireless Sensor Network Energy Consumption Reduction

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Computers, Materials & Continua 2022年第7期72卷 1611-1626页

作者： Huma Hasan Rizvi Sadiq Ali Khan Rabia Noor Enam Kashif Nisar Muhammad Reazul Haque Computer Science Department UBIT Karachi UniversityKarachi75270Pakistan Sir Syed University of Engineering and Technology Karachi75300Pakistan Faculty of Computing and Informatics University Malaysia SabahJalan UMS88400Kota KinabaluSabahMalaysia Faculty of Computing&Informatics Multimedia UniversityPersiaran Multimedia63100CyberjayaSelangorMalaysia

In an Underwater Wireless Sensor Network(UWSN),extreme energy loss is carried out by the early expiration of sensor nodes and causes a reduction in efficiency in the submerged acoustic sensor system.Systems based on clustering strategies,instead of each node sending information by itself,utilize cluster heads to collect information inside the clusters for forwarding collective information to sink.This can effectively minimize the total energy loss during transmission.The environment of UWSN is 3D architecture-based and follows a complex hierarchical clustering strategy involving its most effecting unique parameters such as propagation delay and limited transmission bandwidth.Round base clustering strategy works in rounds,where each round comprises three fundamental stages:cluster head selection,grouping or node association,and data aggregation followed by forwarding data to the sink.In UWSN,the energy consumed during the formation of clusters has been considered casually or completely evaded in the previous works.In this paper,the cluster head setup period has been considered the main contributor to extra energy utilizer.A numerical channel model is proposed to compute extra energy.It is performed by using a UWSN broad model.The results have shown that extra maximum energy consumption is approximately 12.9 percent of the system total energy consumed in information transmissions.

关键词： Analytical model submerged acoustic sensor systems energy loss round base clustering UWSN extra energy

Analytical model of cutting force in axial ultrasonic vibration-assisted milling in-situ TiB_(2)/7050Al PRMMCs

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Chinese Journal of Aeronautics 2021年第4期34卷 160-173页

作者： Xiaofen LIU Wenhu WANG Ruisong JIANG Yifeng XIONG Kunyang LIN Junchen LI Chenwei SHAN Key Laboratory of High Performance Manufacturing for Aero Engine Ministry of Industry and Information TechnologySchool of Mechanical EngineeringNorthwestern Polytechnical UniversityXi'an 710072China Engineering Research Center of Advanced Manufacturing Technology for Aero Engine Ministry of EducationSchool of Mechanical EngineeringNorthwestern Polytechnical UniversityXi'an 710072China School of Aeronautics and Astronautics Sichuan UniversityChengdu 610065China

Ultrasonic vibration-assisted milling has been widely applied in machining the difficultto-cut materials owing to the remarkable improvements in reducing the cutting force.However,Analytical models to reveal the mechanism and predict the cutting force of ultrasonic vibrationassisted milling metal matrix composites are still needed to be developed.In this paper,an Analytical model of cutting force was established for ultrasonic vibration-assisted milling in-situ TiB_(2)/7050 Al metal matrix composites.During modeling,change of motion of the cutting tool,contact of toolchip-workpiece and acceleration of the chip caused by ultrasonic vibration was considered based on equivalent oblique cutting model.Meanwhile,material properties,tool geometry,cutting parameters and vibration parameters were taken into consideration.Furthermore,the developed analytical force model was validated with and without ultrasonic vibration milling experiments on in-situ TiB_(2)/7050 Al metal matrix composites.The predicted cutting forces show to be consistent well with the measured cutting forces.Besides,the relative error of instantaneous maximum forces between the predicted and measured data is from 0.4%to 15.1%.The Analytical model is significant for cutting force prediction not only in ultrasonic-vibration assisted milling but also in conventional milling in-situ TiB_(2)/7050 Al metal matrix composites,which was proved with general applicability.

关键词： Al-MMCs Analytical model Cutting force In-situ Milling TiB_(2)particles Ultrasonic vibration

Analytical model of tilted driver–pickup coils for eddy current nondestructive evaluation

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Chinese Physics B 2018年第3期27卷 125-131页

作者：曹丙花李超范孟豹叶波田贵云 School of Information and Control Engineering China University of Mining and Technology Jiangsu Key Laboratory of Mine Mechanical and Electrical Equipment China University of Mining and Technology School of Mechatronic Engineering China University of Mining and Technology Faculty of Information Engineering and Automation Kunming University of Science and Technology School of Electrical and Electronic Engineering Newcastle University

A driver-pickup probe possesses better sensitivity and flexibility due to individual optimization of a coil. It is fre- quently observed in an eddy current （EC） array probe. In this work, a tilted non-coaxial driver-pickup probe above a multilayered conducting plate is analytically modeled with spatial transformation for eddy current nondestructive evalua- tion. Basically, the core of the formulation is to obtain the projection of magnetic vector potential （MVP） from the driver coil onto the vector along the tilted pickup coil, which is divided into two key steps. The first step is to make a projection of MVP along the pickup coil onto a horizontal plane, and the second one is to build the relationship between the pr, ojected MVP and the MVP along the driver coil. Afterwards, an Analytical model for the case of a layered plate is established with the reflection and transmission theory of electromagnetic fields. The calculated values from the resulting model indicate good agreement with those from the finite element model （FEM） and experiments, which validates the developed Analytical model.

关键词： nondestructive evaluation eddy currents tilted coils Analytical model

A quantum efficiency Analytical model for complementary metal–oxide–semiconductor image pixels with a pinned photodiode structure

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Chinese Physics B 2014年第12期23卷 254-262页

作者：曹琛张冰吴龙胜李娜王俊峰 Xi'an Microelectronics Technology Institute

A quantum efficiency Analytical model for complementary metal–oxide–semiconductor（CMOS） image pixels with a pinned photodiode structure is developed. The proposed model takes account of the non-uniform doping distribution in the N-type region due to the impurity compensation formed by the actual fabricating process. The characteristics of two boundary PN junctions located in the N-type region for the particular spectral response of a pinned photodiode, are quantitatively analyzed. By solving the minority carrier steady-state diffusion equations and the barrier region photocurrent density equations successively, the analytical relationship between the quantum efficiency and the corresponding parameters such as incident wavelength, N-type width, peak doping concentration, and impurity density gradient of the N-type region is established. The validity of the model is verified by the measurement results with a test chip of 160×160 pixels array,which provides the accurate process with a theoretical guidance for quantum efficiency design in pinned photodiode pixels.

关键词： CMOS image sensor quantum efficiency pinned photodiode Analytical model

Two dimensional Analytical model for a negative capacitance double gate tunnel field effect transistor with ferroelectric gate dielectric

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Journal of Semiconductors 2018年第10期39卷 39-45页

作者： Huifang Xu Institute of Electrical and Electronic Engineering Anhui Science and Technology University

Analytical models are presented for a negative capacitance double-gate tunnel field-effect transistor（NC DG TFET） with a ferroelectric gate dielectric in this paper. The model accurately calculates the channel potential profile by solving the Poisson equation with the Landau-Khalatnikov（LK） equation. Moreover, the effects of the channel mobile charges on the potential are also taken into account. We also analyze the dependences of the channel potential and the on-state current on the device parameters by changing the thickness of ferroelectric layer,ferroelectric material and also verify the simulation results accord with commercial TCAD. The results show that the device can obtain better characteristics when the thickness of the ferroelectric layer is larger as it can reduce the shortest tunneling length.

关键词： ferroelectric gate dielectric double-gate tunnel field-effect transistor Analytical model

Analytical model for predicting time-dependent lateral deformation of geosynthetics-reinforced soil walls with modular block facing

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 711-725页

作者： Luqiang Ding Chengzhi Xiao Feilong Cui School of Civil and Transportation Engineering Hebei University of TechnologyTianjin300401China

To date,few models are available in the literature to consider the creep behavior of geosynthetics when predicting the lateral deformation(d)of geosynthetics-reinforced soil(GRS)retaining walls.In this study,a general hyperbolic creep model was first introduced to describe the long-term deformation of geosynthetics,which is a function of elapsed time and two empirical parameters a and b.The conventional creep tests with three different tensile loads(Pr)were conducted on two uniaxial geogrids to determine their creep behavior,as well as the a-Pr and b-Pr relationships.The test results show that increasing Pr accelerates the development of creep deformation for both geogrids.Meanwhile,a and b respectively show exponential and negatively linear relationships with Pr,which were confirmed by abundant experimental data available in other studies.Based on the above creep model and relationships,an accurate and reliable Analytical model was then proposed for predicting the time-dependent d of GRS walls with modular block facing,which was further validated using a relevant numerical investigation from the previous literature.Performance evaluation and comparison of the proposed model with six available prediction models were performed.Then a parametric study was carried out to evaluate the effects of wall height,vertical spacing of geogrids,unit weight and internal friction angle of backfills,and factor of safety against pullout on d at the end of construction and 5 years afterwards.The findings show that the creep effect not only promotes d but also raises the elevation of the maximum d along the wall height.Finally,the limitations and application prospects of the proposed model were discussed and analyzed.

关键词： Geosynthetics Creep behavior Geosynthetics-reinforced soil(GRS)walls Lateral deformation Analytical model

A simple Analytical model of laser direct-drive thin shell target implosion

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Chinese Physics B 2022年第4期31卷 481-485页

作者：余波黄天晅姚立孙传奎尚万里王鹏彭晓世唐琦宋仔峰蒋炜陈忠靖蒲昱东晏骥董云松杨家敏丁永坤郑坚 School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026China Research Center of Laser Fusion China Academy of Engineering PhysicsMianyang 621900China Institute of Applied Physics and Computational Mathematics Beijing 100088China IFSA Collaborative Innovation Center Shanghai Jiao Tong UniversityShanghai 200240China

A high-neutron yield platform imploded by a thin shell target is generally built to probe nuclear science problems,and it has the advantages of high neutron yield,ultrashort fusion time,micro fusion zone,isotropic and monoenergetic neutron.Some Analytical models have been proposed to interpret exploding-pusher target implosion driven by a long wavelength laser,whereas they are imperfect for a 0.35 μm laser implosion experiment.When using the 0.35 μm laser,the shell is ablated and accelerated to high implosion velocity governed by Newton’s law,ablation acceleration and quasi-adiabatic compression models are suitable to explain the implosion of a laser direct-drive thin shell target.The new Analytical model scales bang time,ion temperature and neutron yield for large variations in laser power,target radius,shell thickness,and fuel pressure.The predicted results of the Analytical model are in agreement with experimental data on the ShenguangIII prototype laser facility,100 kJ laser facility,Omega,and NIF,it demonstrates that the Analytical model benefits the understanding of experiment performance and optimizing the target design of high neutron yield implosion.

关键词： direct drive Analytical model thin shell target neutron yield

Simplified Analytical model for Estimation of Switching Loss of Cascode GaN HEMTs in Totem-pole PFC Converters

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Chinese Journal of Electrical Engineering 2019年第3期5卷 1-9页

作者： Qiqi Li Bangyin Liu Shanxu Duan State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China

A practical Analytical model to calculate the switching loss of cascode gallium nitride high electron mobility transistors(GaN HEMTs)is proposed.To facilitate analysis and application,the transmission delays introduced by Si MOSFET and interconnection inductances are ignored in modeling.Meanwhile,the nonlinear junction capacitances of the device and circuit stray inductances are also incorporated to increase the accuracy of the model.The turn-on and turn-off switching processes are described in detail and the simplified equations can be easily solved by using mathematical tools.Based on the Analytical model,loss evaluation of totem-pole PFC converter is introduced briefly.Finally,the accuracy of the model is validated by comparing the calculated loss and converter’s efficiency with experiment results.Peak efficiency of 99.26%is achieved for a 3.6 kW single phase CCM Totem-Pole PFC AC/DC converter switching at 50 kHz based on 650 V cascode GaN HEMTs.

关键词： Analytical model cascode GaN HEMTs totem-pole PFC efficiency evaluation