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Development of a convolutional neural network based geomechanical upscaling technique for heterogeneous geological reservoir

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2111-2125页

作者： zhiwei ma Xiaoyan Ou Bo Zhang Earth and Environmental Sciences Division Los Alamos National LaboratoryLos AlamosUSA Civil and Environmental Engineering University of AlbertaEdmontonCanada

Geomechanical assessment using coupled reservoir-geomechanical simulation is becoming increasingly important for analyzing the potential geomechanical risks in subsurface geological ***,a robust and efficient geomechanical upscaling technique for heterogeneous geological reservoirs is lacking to advance the applications of three-dimensional(3D)reservoir-scale geomechanical simulation considering detailed geological ***,we develop convolutional neural network(CNN)proxies that reproduce the anisotropic nonlinear geomechanical response caused by lithological heterogeneity,and compute upscaled geomechanical properties from CNN *** CNN proxies are trained using a large dataset of randomly generated spatially correlated sand-shale realizations as inputs and simulation results of their macroscopic geomechanical response as *** trained CNN models can provide the upscaled shear strength(R^(2)>0.949),stress-strain behavior(R^(2)>0.925),and volumetric strain changes(R^(2)>0.958)that highly agree with the numerical simulation results while saving over two orders of magnitude of computational *** is a major advantage in computing the upscaled geomechanical properties directly from geological realizations without the need to perform local numerical simulations to obtain the geomechanical *** proposed CNN proxybased upscaling technique has the ability to(1)bridge the gap between the fine-scale geocellular models considering geological uncertainties and computationally efficient geomechanical models used to assess the geomechanical risks of large-scale subsurface development,and(2)improve the efficiency of numerical upscaling techniques that rely on local numerical simulations,leading to significantly increased computational time for uncertainty quantification using numerous geological realizations.

关键词： Upscaling Lithological heterogeneity Convolutional neural network(CNN) Anisotropic shear strength Nonlinear stressestrain behavior

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Numerical study of a hybrid absorption-compression high temperature heat pump for industrial waste heat recovery

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Frontiers in Energy 2017年第4期11卷 503-509页

作者： zhiwei ma Huashau BAO Anthony Paul ROSKILLY Sir Joseph Swan Centre for Energy Research Newcastle University Newcastle upon Tyne NEI 7RU UK

The present paper aims at exploring a hybrid absorption-compression heat pump （HAC-HP） to upgrade and recover the industrial waste heat in the temperature range of 60℃-120℃. The new HAC-HP system proposed has a condenser, an evaporator, and one more solution pump, compared to the conventional HAC-HP system, to allow flexible utilization of energy sources of electricity and waste heat. In the system proposed, the pressure of ammonia-water vapor desorbed in the generator can be elevated by two routes; one is via the compression of compressor while the other is via the condenser, the solution pump, and the evaporator. The results show that more ammonia-water vapor flowing through the compres- sor leads to a substantial higher energy efficiency due to the higher quality of electricity, however, only a slight change on the system exergy efficiency is noticed. The temperature lift increases with the increasing system recirculation flow ratio, however, the system energy and exergy efficiencies drop towards zero. The suitable operation ranges of HAC-HP are recommended for the waste heat at 60℃, 80℃, 100℃, and 120℃. The recirculation flow ratio should be lower than 9, 6, 5, and 4 respectively for these waste heat, while the temperature lifts are in the range of 9.8℃-27.7 ℃, 14.9℃~4.1 ℃, 24.4℃-64.1 ℃, and 40.7℃-85.7℃, respectively, and the system energy efficiency are 0.35-0.93, 0.32-0.90, 0.25- 0.85, and 0.14-0.76.

关键词： absorption compression high temperatureheat pump efficiency industrial waste heat thermodynamicanalysis

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Desulfurization kinetics of ZnO sorbent loaded on semi-coke support for hot coal gas

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Journal of Natural Gas Chemistry 2012年第5期21卷 556-562页

作者： zhiwei ma Xianrong Zheng Liping Chang Ruiyuan He Weiren Bao Key Laboratory of Coal Science and Technology Taiyuan University of TechnologyMinistry of Education and Shanxi ProvinceTaiyuan 030024ShanxiChina

Zn-based sorbent （Z20SC） prepared through semi-coke support in 20 wt% zinc nitrate solution by high-pressure impregnation presents an excellent desulfurization capacity in hot coal gas,in which H2 S can not be nearly detected in the outlet gas before 20 h breakthrough *** effects of the main operational conditions and the particle size of Z20SC sorbent on its desulfurization performances sorbent were investigated in a fixed-bed reactor and the desulfurization kinetics of Z20SC sorbent removing H2 S from hot coal gas was calculated based on experimental *** showed that the conversion of Z20SC sorbent desulfurization reaction increased with the decrease of the particle size of the sorbent and the increases of gas volumetric flow rate,reaction temperature and H 2 S content in inlet gas.Z20SC sorbent obtained from hydrothermal synthesis by high-pressure impregnation possessed much larger surface area and pore volume than semi-coke support,and they were significantly reduced after the desulfurization *** equivalent grain model was reasonably used to analyze experimental data,in which k s=4.382×10-3 exp（-8.270×103/RgT） and Dep=1.262×10-4exp（1.522×104/RgT）.It suggests that the desulfurization reaction of the Z20SC sorbent is mainly controlled by the chemical reaction in the initial stage and later by the diffusion through the reacted sorbent layer.

关键词： desulfurization kinetics Zn-based sorbent hot coal gas medium-temperature desulfurization

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Generation of Alfvén wave energy during magnetic reconnection in Hall MHD

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Plasma Science and Technology 2017年第10期19卷 5-13页

作者： Lingjie LI zhiwei ma Licheng WANG Institute for Fusion Theory and Simulation Zhejiang University Hangzhou 310027 People＇s Republic of China

The effect of the reconnection rate on the generation of Alfvén wave energy is systematically investigated using Hall magnetohydrodynamics（MHD）. It is well known that a decrease in magnetic energy is proportional to the reconnection rate. It is found that an instantaneous increase in Alfvén wave energy in unit Alfvén time is the square dependence on the reconnection rate. The converted Alfvén wave energy is strongly enhanced due to the large increase in the reconnection rate in Hall MHD. For solar-terrestrial plasmas, the maximum converted Alfvén wave energy in unit Alfvén time with the Hall effect can be over 50 times higher than that without the Hall effect during magnetic reconnection.

关键词： magnetic reconnection Alfvén wave energy Hall effect

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Roles of initial current carrier in the distribution of field-aligned current in 3-D Hall MHD simulations

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Science China(Technological Sciences) 2008年第3期51卷 323-336页

作者： ZHANG XianGuo PU ZuYin ma zhiwei ZHOU XuZhi Institute of Space Physics and Applied Technology School of Earth and Space SciencePeking UniversityBeijing 100871China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China Institute of Fusion Theory and Simulation School of ScienceZhejiang UniversityHangzhou 310027China

A three-dimensional (3-D) Hall MHD simulation is carried out to study the roles of initial current carrier in the topology of magnetic field, the generation and distribu- tion of field aligned currents (FACs), and the appearance of Alfvén waves. Consid- ering the contribution of ions to the initial current, the topology of the obtained magnetic field turns to be more complex. In some cases, it is found that not only the traditional By quadrupole structure but also a reversal By quadrupole structure appears in the simulation box. This can explain the observational features near the diffusion region, which are inconsistent with the Hall MHD theory with the total ini- tial current carried by electrons. Several other interesting features are also emerged. First, motions of electrons and ions are decoupled from each other in the small plasma region (Hall effect region) with a scale less than or comparable with the ion inertial length or ion skin depth di=c/ωp. In the non-Hall effect region, the global magnetic structure is shifted in +y direction under the influence of ions with initial y directional motion. However, in the Hall effect region, magnetic field lines are bent in ?y direction, mainly controlled by the motion of electrons, then By is generated. Second, FACs emerge as a result of the appearance of By. Compared with the prior Hall MHD simulation results, the generated FACs shift in +y direction, and hence the dawn-dusk symmetry is broken. Third, the Walén relation in our simulations is consistent with the Walén relation in Hall plasma, thus the presence of Alfvén wave is confirmed.

关键词： collisionless magnetic reconnection Hall MHD simulation field aligned current (FAC) Alfvén wave Hall effects

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miR-192-5p在增生性瘢痕组织及成纤维细胞中的表达及调控

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中国组织工程研究 2025年第12期29卷 2500-2506页

作者：赵皎均田文融卜盼盼齐郁松马志伟李培培马少林新疆医科大学第一附属医院新疆维吾尔自治区乌鲁木齐市830011

背景:研究表明,miRNAs的表达与肝纤维化、肾纤维化及皮肤纤维化发生有关;并证实在痛风性关节炎中miR-192-5p与表皮调节素存在靶向调控关系。目的:探讨miR-192-5p在增生性瘢痕中的表达及调控作用,并验证miR-192-5p与表皮调节素之间存在... 详细信息

背景:研究表明,miRNAs的表达与肝纤维化、肾纤维化及皮肤纤维化发生有关;并证实在痛风性关节炎中miR-192-5p与表皮调节素存在靶向调控关系。目的:探讨miR-192-5p在增生性瘢痕中的表达及调控作用,并验证miR-192-5p与表皮调节素之间存在靶向调控关系。方法:①在新疆医科大学第一附属医院收集6例增生性瘢痕组织及6例正常皮肤组织,采用qRT-PCR法检测miR-192-5p与表皮调节素mRNA表达。②组织块法获取原代增生性瘢痕成纤维细胞,传代培养至3-6代用于后续实验,实验分为3个组:阴性对照组、miR-192-5p模拟物组和miR-192-5p抑制物组,分别转染对应的序列。采用CCK-8法和EdU试剂盒检测细胞增殖活力,划痕实验检测细胞迁移能力,流式细胞术检测细胞凋亡,qRT-PCR和Western blot法检测表皮调节素、Ⅰ型胶原、Ⅲ型胶原和α-Sma的基因和蛋白表达,生物信息学网站预测miR-192-5p靶点,双荧光素酶实验验证靶向结合。结果与结论:①与正常皮肤组织及其成纤维细胞相比,miR-192-5p和表皮调节素在增生性瘢痕和增生性瘢痕成纤维细胞中均呈高表达(P<0.05或P<0.01);②过表达miR-192-5p后,与阴性对照组比较,细胞增殖能力增强(P<0.05),EdU阳性细胞率增加(P<0.01);抑制miR-192-5p后细胞活力降低(P<0.05),EdU阳性细胞率减少(P<0.05);③过表达miR-192-5p 24 h后,与阴性对照组比较,模拟物组细胞划痕间面积、细胞凋亡率减小(P<0.05),miR-192-5p抑制物组细胞划痕间面积、细胞凋亡率增加(P<0.01);④转染48 h后,miR-192-5p模拟物组表皮调节素mRNA及蛋白水平显著降低、Ⅰ型胶原、Ⅲ型胶原和α-平滑肌肌动蛋白mRNA及蛋白水平显著增高(P<0.05或P<0.01);miR-192-5p抑制物组上述4项指标呈现相反的变化(P<0.05或P<0.01);⑤Targetscan网站预测表皮调节素与miR-192-5p有潜在结合位点;⑥双荧光素酶实验显示,miR-192-5p能够与表皮调节素靶向结合。结果说明:miR-192-5p过表达可降低表皮调节素的表达,二者可能存在负向调控;提示通过调控表皮调节素可能起到抑制增生性瘢痕成纤维细胞增殖的作用。

关键词：增生性瘢痕 miR-192-5p 表皮调节素成纤维细胞

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Sawtooth-like oscillations and steady states caused by the m/n=2/1 double tearing mode

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Plasma Science and Technology 2022年第3期24卷 89-97页

作者： Wei ZHANG zhiwei ma Haowei ZHANG Xin WANG Institute for Fusion Theory and Simulation Department of PhysicsZhejiang UniversityHangzhou 310027People's Republic of China

The sawtooth-like oscillations resulting from the m/n=2/1 double tearing mode(DTM)are numerically investigated through the three-dimensional,toroidal,nonlinear resistive-MHD code(CLT).We find that the nonlinear evolution of the m/n=2/1 DTM can lead to sawtooth-like oscillations,which are similar to those driven by the kink *** perpendicular thermal conductivity and the external heating rate can significantly alter the behaviors of the DTM driven sawtooth-like *** a high perpendicular thermal conductivity,the system quickly evolves into a steady state with m/n=2/1 magnetic islands and helical ***,with a low perpendicular thermal conductivity,the system tends to exhibit sawtooth-like *** a sufficiently high or low heating rate,the system exhibits sawtooth-like oscillations,while with an intermediate heating rate,the system quickly evolves into a steady *** the steady state,there exist the non-axisymmetric magnetic field and strong radial flow,and both are with helicity of m/n=2/*** the steady state with m/n=1/1 radial flow,which is beneficial for preventing the helium ash accumulation in the core,the steady state with m/n=2/1 radial flow might also be a good candidate for the advanced steady state operations in future fusion *** also find that the behaviors of the sawtooth-like oscillations are almost independent of tokamak geometry,which implies that the steady state with saturated m/n=2/1 islands might exist in different tokamaks.

关键词： DTM reversed magnetic shear pressure crash sawteeth sawtooth double tearing mode steady state advanced scenario

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Effect of toroidal mode coupling on explosive dynamics of m/n=3/1 double tearing mode

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Plasma Science and Technology 2024年第10期26卷 8-16页

作者： Xingqiang LU Ge GAO zhiwei ma Wei GUO Xin LI College of Nuclear Equipment and Nuclear Engineering Yantai UniversityYantai 264005People’s Republic of China Institute for Fusion Theory and Simulation Department of PhysicsZhejiang UniversityHangzhou 310027People’s Republic of China

The CLT code was used to quantitatively study the impact of toroidal mode coupling on the explosive dynamics of the m/n=3/1 double tearing *** focus of this study was on explosive reconnection processes,in which the energy bursts and the main mode no longer dominates when the separation between two rational surfaces is relatively large in the medium *** development of higher m and n modes is facilitated by a relatively large separation between two rational surfaces,a small q_(min)(the minimum value of the safety factor),or low *** relationships between the higher m and n mode development,explosive reconnection rate,and position exchange of 3/1 islands are summarized for the first *** plays a more important role than q_(min)in enhancing the development of higher m and n *** a relatively large separation,the good development of higher m and n modes greatly reduces the reconnection rate and suppresses the development of the main mode,resulting in the main mode not being able to develop sufficiently large to generate the position changes of 3/1 islands.

关键词： toroidal mode coupling higher m and n modes explosive growth reconnection rate position change

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Free-boundary plasma equilibria with toroidal plasma flows

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Plasma Science and Technology 2022年第3期24卷 61-70页

作者： Wenjin CHEN zhiwei ma Haowei ZHANG Wei ZHANG Longwen YAN Institute for Fusion Theory and Simulation.Zhejiang University Hangzhou 310027People's Republic of China Southwestern Institute of Physics Chengdu 610225People's Republic of China

magnetohydrodynamic equilibrium schemes with toroidal plasma flows and scrape-off layer are developed for the'divertor-type'and'limiter-type'free boundaries in the tokamak cylindrical *** a toroidal plasma flow,the flux functions are considerably different under the isentropic and isothermal *** effects of the toroidal flow on the magnetic axis shift are *** a high beta plasma,the magnetic shifts due to the toroidal flow are almost the same for both the isentropic and isothermal cases and are about 0.04a_(0)(a_(0)is the minor radius)for M_(0)=0.2(the toroidal Alfvén mach number on the magnetic axis).In addition,the X-point is slightly shifted upward by 0.0125a_(0).But the magnetic axis and the X-point shift due to the toroidal flow may be neglected because M_(0) is usually less than 0.05 in a real *** effects of the toroidal flow on the plasma parameters are also *** high toroidal flow shifts the plasma outward due to the centrifugal *** profiles are noticeable different because the plasma temperature is a flux function in the isothermal case.

关键词： tokamak plasma plasma flow equilibria

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Validation of the current and pressure coupling schemes with nonlinear simulations of TAE and analysis on the linear stability of tearing mode in the presence of energetic particles

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Plasma Science and Technology 2023年第4期25卷 39-50页

作者：张豪伟马志为 Institute for Fusion Theory and Simulation School of PhysicsZhejiang UniversityHangzhou 310027People’s Republic of China

Both current and pressure coupling schemes have been adopted in the hybrid kinetic–magnetohydrodynamic code CLT-K *** equivalences between these two coupling schemes are strictly verified under different ***,when considering only the perturbed distribution function of energetic particles(EPs),the equivalence can be proved ***,when both the variations of the magnetic field and the EP distribution function are included,the current and pressure coupling schemes numerically produce the same result in the nonlinear *** this basis,the influences of co-/counter-passing and trapped EPs on the linear stabilities of the m/n=2/1 tearing mode(TM)have been investigated(where m and n represent the poloidal and toroidal mode numbers,respectively).The results of scanningβh of EPs show that the co-passing and trapped EPs are found to stabilize the TM,while the counter-passing EPs tend to destabilize the *** behind(de)stabilization mechanisms of the TM by EPs are carefully ***,after exceeding critical EP betas,the same branch of the high-frequency mode is excited by co-/counterpassing and trapped EPs,which is identified as the m/n=2/1 energetic particle mode.

关键词： hybrid kinetic–magnetohydrodynamic simulation tearing mode energetic particle

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