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Mutual impact of true triaxial stress, borehole orientation and bedding inclination on laboratory hydraulic fracturing of Lushan shale

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第12期15卷 3131-3147页

作者： Yongfa Zhang Anfa Long Yu Zhao arno zang Chaolin Wang College of Civil Engineering Guizhou UniversityGuiyang550025China Helmholtz Centre Potsdam GFZ German Research Centre for GeosciencesPotsdam14473Germany

Unconventional resources like shale gas has been the focus of intense research and development for two decades. Apart from intrinsic geologic factors that control the gas shale productivity (e.g. organic matter content, bedding planes, natural fractures, porosity and stress regime among others), external factors like wellbore orientation and stimulation design play a role. In this study, we present a series of true triaxial hydraulic fracturing experiments conducted on Lushan shale to investigate the interplay of internal factors (bedding, natural fractures and in situ stress) and external factors (wellbore orientation) on the growth process of fracture networks in cubic specimens of 200 mm in length. We observe relatively low breakdown pressure and fracture propagation pressure as the wellbore orientation and/or the maximum in situ stress is subparallel to the shale bedding plane. The wellbore orientation has a more prominent effect on the breakdown pressure, but its effect is tapered with increasing angle of bedding inclination. The shale breakdown is followed by an abrupt response in sample displacement, which reflects the stimulated fracture volume. Based on fluid tracer analysis, the morphology of hydraulic fractures (HF) is divided into four categories. Among the categories, activation of bedding planes (bedding failure, BF) and natural fractures (NF) significantly increase bifurcation and fractured areas. Under the same stress regime, a horizontal wellbore is more favorable to enhance the complexity of hydraulic fracture networks. This is attributed to the relatively large surface area in contact with the bedding plane for the horizontal borehole compared to the case with a vertical wellbore. These findings provide important references for hydraulic fracturing design in shale reservoirs.

关键词： True triaxial hydraulic fracturing experiment In situ stress state Bedding planes Natural fractures Wellbore orientation Shale reservoirs

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The role of temperature‐enhanced fault closure in promoting postinjection pressure diffusion and seismicity in enhanced geothermal systems

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Deep Underground Science and Engineering 2023年第4期2卷 394-405页

作者： Yinlin Ji Yuedu Chen Hannes Hofmann Yuan Zhang arno zang Günter Zimmermann Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences PotsdamGermany Key Laboratory of In‐situ Property‐improving Mining of Ministry of Education Taiyuan University of TechnologyTaiyuanChina Institute of Applied Geosciences Technische Universität BerlinBerlinGermany Key Laboratory of Deep Coal Resource Mining(CUMT) Ministry of EducationSchool of MinesChina University of Mining and TechnologyXuzhouChina

Post shut‐in seismic events in enhanced geothermal systems(EGSs)occur predominantly at the outer rim of the co‐injection seismic cloud.The concept of postinjection fracture and fault closure near the injection well has been proposed and validated as a mechanism for enhancing post shut‐in pressure diffusion that promotes seismic hazard.This phenomenon is primarily attributed to the poro‐elastic closure of fractures resulting from the reduction of wellbore pressure after injection termination.However,the thermal effects in EGSs,mainly including heat transfer and thermal stress,may not be trivial and their role in postinjection fault closure and pressure evolution needs to be explored.In this study,we performed numerical simulations to analyze the relative importance of poro‐elasticity,heat transfer,and thermo‐elasticity in promoting postinjection fault closure and pressure diffusion.The numerical model wasﬁrst validated against analytical solutions in terms ofﬂuid pressure diffusion and against heatedﬂow‐through experiments in terms of thermal processes.We then quantiﬁed and distinguished the contribution of each individual mechanism by comparing four different shut‐in scenarios simulated under different coupled conditions.Our results highlight the importance of poro‐elastic fault closure in promoting postinjection pressure buildup and seismicity,and suggest that heat transfer can further augment the fault closure‐induced pressure increase and thus potentially intensify the postinjection seismic hazard,with minimal contribution from thermo‐elasticity.

关键词： enhanced geothermal system(EGS) fault closure hydraulic stimulation postinjection seismicity thermal effects thermo‐poro‐elasticity

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长宁地区复杂地震活动的力学成因分析

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地球物理学报 2021年第1期64卷 1-17页

作者：胡幸平崔效锋张广伟王甘娇 arno zang 史丙新姜大伟应急管理部国家自然灾害防治研究院北京100085 江西省地震局南昌330039 GFZ German Research Centre for Geosciences Telegrafenberg14473 PotsdamGermany 四川省地震局成都610041

长宁地区地震活动复杂,发生在长宁背斜轴部的长宁MS6.0地震及其后续中强余震的震源机制与相距仅十几公里的南部向斜区内的中强震具有显著差异;这种差异仅仅是由于发震断层构造不同所造成的,还是孕育地震的应力场本身也存在局部变化?为... 详细信息

长宁地区地震活动复杂,发生在长宁背斜轴部的长宁MS6.0地震及其后续中强余震的震源机制与相距仅十几公里的南部向斜区内的中强震具有显著差异;这种差异仅仅是由于发震断层构造不同所造成的,还是孕育地震的应力场本身也存在局部变化?为了回答这一问题,本文在通过双差层析成像反演修正小震定位和波速结构的基础上,利用小震综合震源机制解方法获取了长宁地区地壳应力场的精细结构,并据此分析了其与中强震震源机制解的力学一致性.研究发现,长宁地区地壳应力场的最大主应力轴在整个区域内基本都处于近水平状态,其方位虽由北向南发生了一定角度的顺时针旋转,但也基本保持为近东西向;相比之下,应力类型在长宁背斜轴部和南部向斜区之间存在显著差异——前者为逆冲型,而后者为走滑型.同时,这两个局部区域的应力场与对应区域内的中强震震源机制解的吻合度较高,但与非对应区域内的中强震震源机制解的吻合度较低,甚至在力学上是相抵触的,表明区域应力场的局部改变是长宁地区复杂地震活动的必要力学基础.通过岩石力学估算,本文认为岩石泊松比的横向差异很可能是造成这种应力场局部改变的主要成因.此外,本文还对长宁MS6.0地震序列的发震构造进行了探讨,认为长宁背斜轴部在6~9 km深度内存在基底断层,而正是这种基底断层在区域应力场作用下发生错动导致了长宁MS6.0地震序列的发生.

关键词：长宁地区复杂地震活动应力场局部变化岩石泊松比基底断层

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Implementation and validation of a bonded particle model to predict rheological properties of viscoelastic materials

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Particuology 2024年第6期89卷 198-210页

作者： Michael Mascara arno Mayrhofer Stefan Radl Christoph Kloss Institute of Process and Particle Engineering Graz University of TechnologyInffeldgasse 13Graz8010Austria DCS Computing GmbH Industriezeile 35Linz4020Austria

This work focuses on implementing a particle-based method able to characterize viscoelastic materials whose rheological properties,such as storage modulus G′and loss modulus G″,are known.It is based on the bonded particle model,with the elastic constitutive relation here substituted with a viscoelastic one to capture time-scale effects.The Burgers model,vastly used in literature to model viscoelastic systems,is discretized and implemented.The test case used for calibration comprises of a cubic lattice,sheared with a periodic motion,to mimic the effect of a shear rheometer.After appropriate filtering of the stress response,the rheological properties are obtained,highlighting the effect of the lattice geometry,as well as the particle size,on the accuracy of the model.Moreover,the Burgers parameters are calibrated by analytically fitting the experimental dataset,showing the limitation of the Burgers model.The micro-contact parameters are obtained from the macro parameters through appropriate scaling.After completing a frequency sweep,the simulated G′and G″show a relatively large error,around 25%for G’for example.For this reason,a more robust model,namely the generalized Maxwell model,has been implemented.The calibration procedure is performed in the same fashion as for the Burgers model.Moreover,the tangential micro-contact parameters are scaled w.***.t.the normal ones.This scaling parameter,calledα,is calibrated by minimizing the root mean square error between simulation and experimental data,giving errors below 10%in both G′and G″for a large dataset.Additionally,a full ring plate-plate rheometer setup is simulated,and the simulation is compared with the given experimental dataset,again finding a good agreement.

关键词： DEM Rheology Numerical modeling Viscoelasticity

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香椿的树木年轮宽度与超年生殖行为的相互关系:对树轮学研究的警示

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Journal of Plant Ecology 2024年第1期17卷 165-171页

作者： Monique Silva Costa Thaís Jorge de Vasconcellos Claudio Sergio Lisi arno Fritz Neves Brandes Mario Tomazello-Filho Cátia Henriques Callado Instituto de Aplicação Fernando Rodrigues da Silveira Universidade do Estado do Rio de JaneiroRua Barão de Itapagipe96.Rio Comprido 20261-005Rio de JaneiroBrazil Laboratório de Anatomia Vegetal Universidade do Estado do Rio de JaneiroRua São Francisco Xavier524Maracanã20550-013Rio de JaneiroBrazil Departamento de Biologia Universidade Federal de SergipeAv.Marechal Rondon s/n-Rosa Elze.São Cristóvão 49100-000SergipeBrazil Departamento de Biologia Geral Universidade Federal FluminenseRua Prof.Marcos Waldemar de Freitas ReisS/N.Gragoatá24210-201Rio de JaneiroBrazil Escola Superior de Agricultura Luiz de Queiroz Universidade de São PauloAv.Pádua Dias11.Piracicaba 13418-900São PauloBrazil

资源分配到生殖过程涉及到生态和进化因素,可能会减少植物的营养生长。这种相互关系在自然界中不容易观察到,因为有许多参数可以限制生殖结构的产生或生物量的增加。我们将香椿(Cedrela odorata L.,楝科)在里约热内卢州大西洋森林中的... 详细信息

资源分配到生殖过程涉及到生态和进化因素,可能会减少植物的营养生长。这种相互关系在自然界中不容易观察到,因为有许多参数可以限制生殖结构的产生或生物量的增加。我们将香椿(Cedrela odorata L.,楝科)在里约热内卢州大西洋森林中的树木年轮宽度与超年生殖行为相关联。总体而言,生殖结构的发育发生在湿润的年份,在生长季初期没有出现水分亏缺。然而,在这些年份,树木年轮宽度较小。这些结果可能与树木年轮宽度与当地气候之间缺乏相关性有关。因此,我们强调在径向生长研究中纳入生殖数据的重要性,以扩大对热带森林生长变异性的理解。

关键词：植物生长策略树木年轮学树木生态学生殖权衡

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Confirmation of a Sub-Saturn-size Transiting Exoplanet Orbiting a G Dwarf:TOI-1194 b and a Very Low Mass Companion Star: TOI-1251 B from TESS

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Research in Astronomy and Astrophysics 2024年第3期24卷 129-143页

作者： Jia-Qi Wang Xiao-Jun Jiang Jie Zheng Hanna Kellermann arno Riffeser Liang Wang Karen A.Collins Allyson Bieryla Lars A.Buchhave Steve B.Howell Elise Furlan Eric Girardin Joao Gregorio Eric Jensen Felipe Murgas Mesut Yilmaz Sam Quinn Xing Gao Ruo-Yu Zhou Frank Grupp Hui-Juan Wang CAS Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy Of SciencesBeijing 10010China University of Chinese Academy of Sciences Beijing 100049China University Observatory Munich Scheinertrsse 1.D-81679 MunichGemany Max Planck Institute for Extraterrestrial Physics Giessenbachstr.1D-85748 GarchingGermany National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing210042China CAS Key Laboratory of Astronomical Optics&Technology Nanjing Institute of Astronomical Optics&TechnologyNanjing 210042China Center for Astrophysics Harvard&Smithsonian60 Garden Street.CambridgeMA 02138USA National Space Institute Technical University of DenmarkElektrovejDK-2800 KgsLyngbyDenmark NASA Ames Research Center Moffett FieldCA 94035USA NASA Exoplanet Science Institute Caltech/IPACMail Code 100-221200 E.California Blvd.PasadenaCA91125USA Grand Pra Observatory Switzerland Department of Physics Washington UniversitySt.LouisMO 63130.USA Department of Physics and Astronomy Swarthmore CollegeSwarthmorePA 19081USA Instituto de Astrofísica de Canarias(IAC) E-38205 La Laguna.TenerifeSpain Departamento de Astrofísica Universidad de La LagunaSpain Dept.of Astronomy and Space Sciences Ankara UniversityTandogan 06100AnkaraTurkey Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China Urumqi No.1 Senior High School Urumqi 830002China Lijiang Gemini Observatory Lijiang 674199China

We report the confirmation of a sub-Saturn-size exoplanet,TOI-1194 b,with a mass of about 0.456+0.055-0.051M_(J),and a very low mass companion star with a mass of about 96.5±1.5 MJ,TOI-1251 *** candidates provided by the Transiting Exoplanet Survey Satellite(TESS)are suitable for further follow-up observations by ground-based telescopes with small and medium apertures.The analysis is performed based on data from several telescopes worldwide,including telescopes in the Sino-German multiband photometric campaign,which aimed at confirming TESS Objects of Interest(TOIs)using ground-based small-aperture and medium-aperture telescopes,especially for long-period targets.TOI-1194 b is confirmed based on the consistent periodic transit depths from the multiband photometric data.We measure an orbital period of 2.310644±0.000001 days,the radius is 0.767+0.045-0.041RJ and the amplitude of the RV curve is 69.4_(-7.3)^(+7.9)m s^(-1).TOI-1251 B is confirmed based on the multiband photometric and high-resolution spectroscopic data,whose orbital period is 5.963054+0.000002-0.000001days,radius is 0.947+0.035-0.033 R_(J) and amplitude of the RV curve is 9849_(-40)^(+42)ms^(-1).

关键词： planets and satellites fundamental parameters-planets and satellites gaseous planets-stars fundamental parameters-stars low-mass-methods data analysis-techniques photometric-techniques spectroscopic

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SolarGAN:Synthetic annual solar irradiance time series on urban building facades via Deep Generative

能源与人工智能(英文)

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能源与人工智能(英文) 2023年第2期12卷 1-21页

作者： Yufei Zhang arno Schlueter Christoph Waibel Chair of Architecture and Building Systems(A/S) ETH ZurichStefano-Franscini-Platz 18093 ZurichSwitzerland

Building Integrated Photovoltaics (BIPV) is a promising technology to decarbonize urban energy systems viaharnessing solar energy available on building envelopes. While methods to assess solar irradiation, especiallyon rooftops, are well established, the assessment on building facades usually involves a higher effort due tomore complex urban features and obstructions. The drawback of existing physics-based simulation programsare that they require significant manual modeling effort and computing time for generating time resolveddeterministic results. Yet, solar irradiation is highly intermittent and representing its inherent uncertainty maybe required for designing robust BIPV energy systems. Targeting on these drawbacks, this paper proposes adata-driven model based on Deep Generative Networks (DGN) to efficiently generate stochastic ensembles ofannual hourly solar irradiance time series on building facades with uncompromised spatiotemporal resolutionat the urban scale. The only input required are easily obtainable fisheye images as categorical shading maskscaptured from 3D models. In principle, even actual photographs of urban contexts can be utilized, given they are semantically segmented. The potential of our approach is that it may be applied as a surrogate for timeconsuming simulations, when facing lacking information (e.g., no 3D model exists), and to use the generatedstochastic time-series ensembles in robust energy systems planning. Our validations exemplify a good fidelityof the generated time series when compared to the physics-based simulator. Due to the nature of the usedDGNs, it remains an open challenge to precisely reconstruct the ground truth one-to-one for each hour of theyear. However, we consider the benefits of the approach to outweigh the shortcomings. To demonstrate themodel’s relevance for urban energy planning, we showcase its potential for generative design by parametricallyaltering characteristic features of the urban environment and producing corresponding time series on buildingfacades

关键词： Urban solar potential Data-driven Deep Generative Networks(DGN) Building-integrated photovoltaic(BIPV) Generative Adversarial Network(GAN) Variational Autoencoder(VAE)

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Diagnosis,treatment and complications of radial head and neck fractures in the pediatric patient

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World Journal of Orthopedics 2022年第3期13卷 238-249页

作者： arno A Macken Denise Eygendaal Christiaan JA van Bergen Department of Orthopedic Surgery Amphia HospitalBreda 4818 CKNoord-BrabantNetherlands Department of Orthopedic Surgery and Sports medicine Erasmus Medical CentreRotterdam 3015 GDSouth-HollandNetherlands

Radial head and neck fractures represent up to 14%of all pediatric elbow fractures and can be a difficult challenge in the pediatric patient.In up to 39%of proximal radius fractures,there is a concomitant fracture,which can easily be overlooked on the initial standard radiographs.The treatment options for proximal radius fractures in children range from non-surgical treatment,such as immobilization alone and closed reduction followed by immobilization,to more invasive options,including closed reduction with percutaneous pinning and open reduction with internal fixation.The choice of treatment depends on the degree of angulation and displacement of the fracture and the age of the patient;an angulation of less than 30 degrees and translation of less than 50%is generally accepted,whereas a higher degree of displacement is considered an indication for surgical intervention.Fractures with limited displacement and non-surgical treatment generally result in superior outcomes in terms of patient-reported outcome measures,range of motion and complications compared to severely displaced fractures requiring surgical intervention.With proper management,good to excellent results are achieved in most cases,and long-term sequelae are rare.However,severe complications do occur,including radio-ulnar synostosis,osteonecrosis,rotational impairment,and premature physeal closure with a malformation of the radial head as a result,especially after more invasive procedures.Adequate follow-up is therefore warranted.

关键词： Radial head Proximal radius Fracture Pediatrics Closed fracture reduction Open reduction fracture Fracture fixation Synostosis Osteonecrosis

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Direct search for primordial ^(244)Pu in Bayan Obo bastnaesite

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Chinese Chemical Letters 2022年第7期33卷 3522-3526页

作者： Yang Wu Xiongxin Dai Shan Xing Maoyi Luo Marcus Christl Hans-arno Synal Shaochun Hou China Institute for Radiation Protection Taiyuan 030006China Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions Suzhou 215006China Laboratory of Ion Beam Physics ETH ZurichZurich 8093Switzerland Baotou Research Institute of Rare Earths Baotou 014030China

The abundances of heavy elements produced in r-process nucleosynthesis in the early solar system need experimental verification.^(244)Pu could be the heaviest primordial nuclide produced before the formation of the Earth still being detectable today.As recent attempts failed to confirm the discovery of ^(244)Pu signals at a concentration of 1.0×10^(-18)g/g in bastnaesite reported by Hoffman et al.in this study,the total primordial ^(244)Pu in 450 g bastnaesite sample from Bayan Obo ore (China) was measured using ultrasensitive compact accelerator mass spectrometry (AMS).As no ^(244)Pu signal was detected,an upper limit for the ^(244)Pu in our bastnaesite sample was estimated to be 2.1×10^(-20)g/g at 99%confidence level.

关键词： ^(244)Pu Initial abundance ratio of^(244)Pu/^(238)U AMS measurement Pu radiochemistry analysis Bastnaesite

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Drivers’ EEG Responses to Different Distraction Tasks

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Automotive Innovation 2023年第1期6卷 20-31页

作者： Guofa Li Xiaojian Wu arno Eichberger Paul Green Cristina Olaverri‑Monreal Weiquan Yan Yechen Qin Yuezhi Li College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing 400044China Institute of Human Factors and Ergonomics College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen 518060China Institute of Automotive Engineering Graz University of Technology8010 GrazAustria University of Michigan Transportation Research Institute and Department of Industrial and Operations Engineering University of MichiganAnn ArborMI 48109USA Chair ITS‑Sustainable Transport Logistics 4.0 Johannes Kepler University4040 LinzAustria Department of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Laboratory of Neural Engineering College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen 518060China

Driver distraction has been deemed a major cause of traffic accidents.However,drivers’brain response activities to different distraction types have not been well investigated.The purpose of this study is to investigate the response of electroencephalography(EEG)activities to different distraction tasks.In the conducted simulation tests,three secondary tasks(i.e.,a clock task,a 2-back task,and a navigation task)are designed to induce different types of driver distractions.Twenty-four participants are recruited for the designed tests,and differences in drivers’brain response activities concerning distraction types are investigated.The results show that the differences in comprehensive distraction are more significant than that in single cognitive distraction.Friedman test and post hoc two-tailed Nemenyi test are conducted to further identify the differences in band activities among brain regions.The results show that the theta energy in the frontal lobe is significantly higher than that in other brain regions in distracted driving,whereas the alpha energy in the temporal lobe significantly decreases compared to other brain regions.These results provide theoretical references for the development of distraction detection systems based on EEG signals.

关键词： Driving safety Driver distraction EEG Autonomous vehicle

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