Electric power training is essential for ensuring the safety and reliability of the system.In this study,we introduce a novel Abnormal Action Recognition(AAR)system that utilizes a Lightweight Pose Estimation Network(...Electric power training is essential for ensuring the safety and reliability of the system.In this study,we introduce a novel Abnormal Action Recognition(AAR)system that utilizes a Lightweight Pose Estimation Network(LPEN)to efficiently and effectively detect abnormal fall-down and trespass incidents in electric power training scenarios.The LPEN network,comprising three stages—MobileNet,Initial Stage,and Refinement Stage—is employed to swiftly extract image features,detect human key points,and refine them for accurate analysis.Subsequently,a Pose-aware Action Analysis Module(PAAM)captures the positional coordinates of human skeletal points in each frame.Finally,an Abnormal Action Inference Module(AAIM)evaluates whether abnormal fall-down or unauthorized trespass behavior is occurring.For fall-down recognition,three criteria—falling speed,main angles of skeletal points,and the person’s bounding box—are considered.To identify unauthorized trespass,emphasis is placed on the position of the ankles.Extensive experiments validate the effectiveness and efficiency of the proposed system in ensuring the safety and reliability of electric power training.展开更多
We report comprehensive transport, electron microscopy and Raman spectroscopy studies on transition-metal chalcogenides Cu1.89Te single crystals. The metallic Cu1.89Te displays successive metal-semiconductor transitio...We report comprehensive transport, electron microscopy and Raman spectroscopy studies on transition-metal chalcogenides Cu1.89Te single crystals. The metallic Cu1.89Te displays successive metal-semiconductor transitions at low temperatures and almost ideal linear MR when magnetic field up to 33 T. Through the electron diffraction patterns, the stable room-temperature phase is identified as a 3 × 3 × 2 modulated superstructure based on the Nowotny hexagonal structure. The superlattice spots of transmission electron microscopy and scanning tunneling microscopy clearly show the structural transitions from the room-temperature commensurate Ⅰ phase, named as C-Ⅰ phase, to the low temperature commensurate Ⅱ(C-Ⅱ) phase. All the results can be understood in terms of charge density wave(CDW) instability, yielding intuitive evidences for the CDW formations in Cu1.89Te. The additional Raman modes below room temperature further reveal that the zone-folded phonon modes may play an important role on the CDW transitions. Our research sheds light on the novel electron features of Cu1.89Te at low temperature, and may provide potential applications for future nano-devices.展开更多
干热河谷是一种特殊的脆弱生态环境,受复杂的地质条件、气象水文条件与人类工程活动影响,易诱发地质灾害。为揭示国内外干热河谷研究的重点和发展趋势,采用Vosviewer软件对知网和Web of science数据库文献资料进行可视化处理,对发文作...干热河谷是一种特殊的脆弱生态环境,受复杂的地质条件、气象水文条件与人类工程活动影响,易诱发地质灾害。为揭示国内外干热河谷研究的重点和发展趋势,采用Vosviewer软件对知网和Web of science数据库文献资料进行可视化处理,对发文作者及合作关系、研究机构、关键词及发表期刊等内容进行分析。结果表明:(1)目前干热河谷领域正处于探索阶段,还有很大的发展空间;(2)熊东红、张宝军及杨丹等学者在现阶段干热河谷研究中具有较大的影响力;(3)冲沟、水土流失及土壤侵蚀等为干热河谷主要研究领域;(4)由于软件和人为筛选的局限性,对于Vosviewer软件的分析和检索还需要进一步具体探索。研究结果可用于加深对于干热河谷研究的认识,为今后的工作提供参考和支持。展开更多
Hydraulic fracturing is a key technology for the development of unconventional hydrocarbon resources.The proppant placement morphology determines the fracture conductivity,thus affecting the reservoir stimulation effe...Hydraulic fracturing is a key technology for the development of unconventional hydrocarbon resources.The proppant placement morphology determines the fracture conductivity,thus affecting the reservoir stimulation effect.In this paper,the proppant migration and placement within complex fractures was studied by considering the fracture wall roughness through computational fluid mechanics-discrete element method(CFD-DEM)in numerical simulation,which is a key approach to study the proppant migration and placement.The results show that the proppant placement non-uniformity,proppant migration capacity,and proppant volume filled in the far-end and the secondary branched fracture are enhanced within the rough fracture compared with those within smooth fractures.The proppant migration capacity is increased within the fracture at low inclination angles(<60°)and low approach angles(<90°),and the proppant placement area is larger in the inclined fracture than that in the vertical fracture.The rise of injection rate and fracturing fluid viscosity causes more proppants migrate to far-end or secondary fractures,resulting in a non-proppant area within the near-wellbore fracture.An increase by 1.3 times in the injection rate and 3 times in the fracturing fluid viscosity leads to a decrease by 26.6%and 27%,respectively,in the proppant placement area within the near-wellbore fracture.The staged injection with small size proppants followed by large size proppants increases the proppant placement area in the primary fracture by 13%-26%,and that with large size proppants followed by small size proppants increases the proppant placement area by 19%-25%,which is due to that the latter method facilitates filling of the secondary branched fracture.The injection location mainly affects the proppant filling degree within the near-wellbore fractures.Compared with the upper injection,the middle and lower injection is not beneficial to filling of proppants within the near-wellbore fracture.展开更多
Magnetic skyrmions have interesting properties,including their small size,topological stability,and extremely low threshold current for current-driven motion.Therefore,they are regarded as promising candidates for nex...Magnetic skyrmions have interesting properties,including their small size,topological stability,and extremely low threshold current for current-driven motion.Therefore,they are regarded as promising candidates for next-generation magnetic memory devices.Lorentz transmission electron microscopy(TEM)has an ultrahigh magnetic domain resolution(~2 nm),it is thus an ideal method for direct real-space imaging of fine magnetic configurations of ultra-small skyrmions.In this paper,we describe the basic principles of Lorentz-TEM and off-axis electron holography and review recent experimental developments in magnetic skyrmion imaging using these two methods.展开更多
This report describes a 52-year-old male patient with blunt abdominal traumatic rupture of the spleen due to injuries sustained in an automobile accident. Following splenectomy, the patient developed a gastric fistula...This report describes a 52-year-old male patient with blunt abdominal traumatic rupture of the spleen due to injuries sustained in an automobile accident. Following splenectomy, the patient developed a gastric fistula. He underwent a long period of conservative treatment, including antibiotics and total parenteral nutrition, which was ineffective. The fistula could not be closed and titanium clip closure using a gastroscopy was then performed in order to close the fistula. After endoscopic therapy and clipping surgery, the patient's general condition improved significantly, and he had no post-procedural abdominal complications. On postclipping day 6, the gastric fistula was completely closed as shown by X-ray examination of the upper digestive tract. The patient was discharged from hospital and no complications were observed during the six-month follow-up period. Our report suggests that titanium clip closure using endoscopy may be the choice of treatment in patients with a gastric fistula.展开更多
We investigate the ultrafast spin dynamics of an antiferromagnet in a ferromagnet/antiferromagnet heterostructure Fe/GdFeO_(3) via an all-optical method.After laser irradiation,the terahertz spin precession is hard to...We investigate the ultrafast spin dynamics of an antiferromagnet in a ferromagnet/antiferromagnet heterostructure Fe/GdFeO_(3) via an all-optical method.After laser irradiation,the terahertz spin precession is hard to be excited in a bare GdFeO_(3) without spin reorientation phase but efficiently in Fe/GdFeO_(3).Both quasi-ferromagnetic and impurity modes,as well as a phonon mode,are observed.We attribute it to the optical modification of interfacial exchange coupling between Fe and GdFeO3.Moreover,the excitation efficiency of dynamics can be modified significantly via the pump laser influence.Our results elucidate that the interfacial exchange coupling is a feasible stimulation to efficiently excite terahertz spin dynamics in antiferromagnets.It will expand the exploration of terahertz spin dynamics for antiferromagnet-based opto-spintronic devices.展开更多
The magnetic and magnetocaloric properties were studied in a stuffed honeycomb polycrystalline antiferromagnet GdInO_(3).The onset temperature of antiferromagnetic ordering was observed at~2.1 K.Negligible thermal and...The magnetic and magnetocaloric properties were studied in a stuffed honeycomb polycrystalline antiferromagnet GdInO_(3).The onset temperature of antiferromagnetic ordering was observed at~2.1 K.Negligible thermal and magnetic hystereses suggest a reversible magnetocaloric effect(MCE)in the GdInO_(3) compound.In the magnetic field changes of 0 kOe-50 kOe and 0 kOe-70 kOe,the maximum magnetic entropy change values are 9.65 J/kg·K and 18.37 J/kg·K,respectively,near the liquid helium temperature,with the corresponding relative cooling power values of 115.01 J/kg and211.31 J/kg.The MCE investigation of the polycrystalline GdInO_(3) serves to illuminate more exotic properties in this frustrated stuffed honeycomb magnetic system.展开更多
We report dynamics of skyrmion bubbles driven by spin-transfer torque in achiral ferromagnetic nanostripes using micromagnetic simulations.In a three-dimensional uniaxial ferromagnet with a quality factor that is smal...We report dynamics of skyrmion bubbles driven by spin-transfer torque in achiral ferromagnetic nanostripes using micromagnetic simulations.In a three-dimensional uniaxial ferromagnet with a quality factor that is smaller than 1,the skyrmion bubble is forced to stay at the central nanostripe by a repulsive force from the geometry border.The coherent motion of skyrmion bubbles in the nanostripe can be realized by increasing the quality factor to~3.8.Our results should propel the design for future spintronic devices such as artificial neural computing and racetrack memory based on dipolestabilized skyrmion bubbles.展开更多
基金supportted by Natural Science Foundation of Jiangsu Province(No.BK20230696).
文摘Electric power training is essential for ensuring the safety and reliability of the system.In this study,we introduce a novel Abnormal Action Recognition(AAR)system that utilizes a Lightweight Pose Estimation Network(LPEN)to efficiently and effectively detect abnormal fall-down and trespass incidents in electric power training scenarios.The LPEN network,comprising three stages—MobileNet,Initial Stage,and Refinement Stage—is employed to swiftly extract image features,detect human key points,and refine them for accurate analysis.Subsequently,a Pose-aware Action Analysis Module(PAAM)captures the positional coordinates of human skeletal points in each frame.Finally,an Abnormal Action Inference Module(AAIM)evaluates whether abnormal fall-down or unauthorized trespass behavior is occurring.For fall-down recognition,three criteria—falling speed,main angles of skeletal points,and the person’s bounding box—are considered.To identify unauthorized trespass,emphasis is placed on the position of the ankles.Extensive experiments validate the effectiveness and efficiency of the proposed system in ensuring the safety and reliability of electric power training.
基金supported by the National Natural Science Foundation of China(Grant Nos.U19A2093,11904002,U2032214,U2032163,and 11774353)the National Key Research and Development Program of China(Grant No.2017YFA0403502)+1 种基金the Natural Science Foundation of Anhui Province(Grant No.1908085QA15)the Youth Innovation Promotion Association CAS(Grant No.2017483)。
文摘We report comprehensive transport, electron microscopy and Raman spectroscopy studies on transition-metal chalcogenides Cu1.89Te single crystals. The metallic Cu1.89Te displays successive metal-semiconductor transitions at low temperatures and almost ideal linear MR when magnetic field up to 33 T. Through the electron diffraction patterns, the stable room-temperature phase is identified as a 3 × 3 × 2 modulated superstructure based on the Nowotny hexagonal structure. The superlattice spots of transmission electron microscopy and scanning tunneling microscopy clearly show the structural transitions from the room-temperature commensurate Ⅰ phase, named as C-Ⅰ phase, to the low temperature commensurate Ⅱ(C-Ⅱ) phase. All the results can be understood in terms of charge density wave(CDW) instability, yielding intuitive evidences for the CDW formations in Cu1.89Te. The additional Raman modes below room temperature further reveal that the zone-folded phonon modes may play an important role on the CDW transitions. Our research sheds light on the novel electron features of Cu1.89Te at low temperature, and may provide potential applications for future nano-devices.
文摘干热河谷是一种特殊的脆弱生态环境,受复杂的地质条件、气象水文条件与人类工程活动影响,易诱发地质灾害。为揭示国内外干热河谷研究的重点和发展趋势,采用Vosviewer软件对知网和Web of science数据库文献资料进行可视化处理,对发文作者及合作关系、研究机构、关键词及发表期刊等内容进行分析。结果表明:(1)目前干热河谷领域正处于探索阶段,还有很大的发展空间;(2)熊东红、张宝军及杨丹等学者在现阶段干热河谷研究中具有较大的影响力;(3)冲沟、水土流失及土壤侵蚀等为干热河谷主要研究领域;(4)由于软件和人为筛选的局限性,对于Vosviewer软件的分析和检索还需要进一步具体探索。研究结果可用于加深对于干热河谷研究的认识,为今后的工作提供参考和支持。
基金financial support of the National Natural Science Foundation of China(Grant No.52074332)express their gratitude to project ZR2020YQ36 supported by Shandong Provincial Science Fund for Excellent Young Scholars。
文摘Hydraulic fracturing is a key technology for the development of unconventional hydrocarbon resources.The proppant placement morphology determines the fracture conductivity,thus affecting the reservoir stimulation effect.In this paper,the proppant migration and placement within complex fractures was studied by considering the fracture wall roughness through computational fluid mechanics-discrete element method(CFD-DEM)in numerical simulation,which is a key approach to study the proppant migration and placement.The results show that the proppant placement non-uniformity,proppant migration capacity,and proppant volume filled in the far-end and the secondary branched fracture are enhanced within the rough fracture compared with those within smooth fractures.The proppant migration capacity is increased within the fracture at low inclination angles(<60°)and low approach angles(<90°),and the proppant placement area is larger in the inclined fracture than that in the vertical fracture.The rise of injection rate and fracturing fluid viscosity causes more proppants migrate to far-end or secondary fractures,resulting in a non-proppant area within the near-wellbore fracture.An increase by 1.3 times in the injection rate and 3 times in the fracturing fluid viscosity leads to a decrease by 26.6%and 27%,respectively,in the proppant placement area within the near-wellbore fracture.The staged injection with small size proppants followed by large size proppants increases the proppant placement area in the primary fracture by 13%-26%,and that with large size proppants followed by small size proppants increases the proppant placement area by 19%-25%,which is due to that the latter method facilitates filling of the secondary branched fracture.The injection location mainly affects the proppant filling degree within the near-wellbore fractures.Compared with the upper injection,the middle and lower injection is not beneficial to filling of proppants within the near-wellbore fracture.
基金Project supported by the National Key Research and Development Program of China,(Grant No.2017YFA0303201)the Key Research Program of Frontier Sciences,CAS,(Grant No.QYZDB-SSW-SLH009)+2 种基金the National Natural Science Foundation of China(Grant Nos.51622105 and 11804343)the President Foundation of Hefei Institutes of Physical Science,CAS(Grant No.YZJJ2018QN15)the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology,(Grant No.2016FXCX001)
文摘Magnetic skyrmions have interesting properties,including their small size,topological stability,and extremely low threshold current for current-driven motion.Therefore,they are regarded as promising candidates for next-generation magnetic memory devices.Lorentz transmission electron microscopy(TEM)has an ultrahigh magnetic domain resolution(~2 nm),it is thus an ideal method for direct real-space imaging of fine magnetic configurations of ultra-small skyrmions.In this paper,we describe the basic principles of Lorentz-TEM and off-axis electron holography and review recent experimental developments in magnetic skyrmion imaging using these two methods.
基金Supported by the Program of Central Financial Support for Local Universities of China,No.SCKBMI-13-004the Project of Sichuan Provincial Health Bureau of China,No.130334
文摘This report describes a 52-year-old male patient with blunt abdominal traumatic rupture of the spleen due to injuries sustained in an automobile accident. Following splenectomy, the patient developed a gastric fistula. He underwent a long period of conservative treatment, including antibiotics and total parenteral nutrition, which was ineffective. The fistula could not be closed and titanium clip closure using a gastroscopy was then performed in order to close the fistula. After endoscopic therapy and clipping surgery, the patient's general condition improved significantly, and he had no post-procedural abdominal complications. On postclipping day 6, the gastric fistula was completely closed as shown by X-ray examination of the upper digestive tract. The patient was discharged from hospital and no complications were observed during the six-month follow-up period. Our report suggests that titanium clip closure using endoscopy may be the choice of treatment in patients with a gastric fistula.
基金Project supported by the National Key Research Program of China(Grant Nos.2018YFF01010303,2017YFB0702702,and 2016YFA0300701)the National Natural Sciences Foundation of China(Grant Nos.52031015,1187411,51427801,and 51871235)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant Nos.QYZDJ-SSW-JSC023,KJZD-SW-M01,and ZDYZ2012-2).
文摘We investigate the ultrafast spin dynamics of an antiferromagnet in a ferromagnet/antiferromagnet heterostructure Fe/GdFeO_(3) via an all-optical method.After laser irradiation,the terahertz spin precession is hard to be excited in a bare GdFeO_(3) without spin reorientation phase but efficiently in Fe/GdFeO_(3).Both quasi-ferromagnetic and impurity modes,as well as a phonon mode,are observed.We attribute it to the optical modification of interfacial exchange coupling between Fe and GdFeO3.Moreover,the excitation efficiency of dynamics can be modified significantly via the pump laser influence.Our results elucidate that the interfacial exchange coupling is a feasible stimulation to efficiently excite terahertz spin dynamics in antiferromagnets.It will expand the exploration of terahertz spin dynamics for antiferromagnet-based opto-spintronic devices.
基金supported by the National Natural Sciences Foundation of China(Grant Nos.12104123 and U1632161)Anhui Provincial Funds for Distinguished Young Scientists of the Nature Science(Grant No.1808085JQ13)+3 种基金the Natural Science Foundation of Anhui Province(Grant No.2008085MF217)Universities Joint Key Laboratory of Photoelectric Detection Science and Technology in Anhui Province(Grant No.2019GDTC06)the open fund project from Anhui Province Key Laboratory of Simulation and Design for Electronic Information System(Grant No.2019ZDSYSZY04)the Project of Leading Backbone Talents in Anhui Provincial Undergraduate Universities,and Undergraduate Innovation and Entrepreneurship Training Program in Anhui Province(Grant No.S202014098164)。
文摘The magnetic and magnetocaloric properties were studied in a stuffed honeycomb polycrystalline antiferromagnet GdInO_(3).The onset temperature of antiferromagnetic ordering was observed at~2.1 K.Negligible thermal and magnetic hystereses suggest a reversible magnetocaloric effect(MCE)in the GdInO_(3) compound.In the magnetic field changes of 0 kOe-50 kOe and 0 kOe-70 kOe,the maximum magnetic entropy change values are 9.65 J/kg·K and 18.37 J/kg·K,respectively,near the liquid helium temperature,with the corresponding relative cooling power values of 115.01 J/kg and211.31 J/kg.The MCE investigation of the polycrystalline GdInO_(3) serves to illuminate more exotic properties in this frustrated stuffed honeycomb magnetic system.
基金the National Natural Science Foundation of China(Grant Nos.12174396 and 12104123)。
文摘We report dynamics of skyrmion bubbles driven by spin-transfer torque in achiral ferromagnetic nanostripes using micromagnetic simulations.In a three-dimensional uniaxial ferromagnet with a quality factor that is smaller than 1,the skyrmion bubble is forced to stay at the central nanostripe by a repulsive force from the geometry border.The coherent motion of skyrmion bubbles in the nanostripe can be realized by increasing the quality factor to~3.8.Our results should propel the design for future spintronic devices such as artificial neural computing and racetrack memory based on dipolestabilized skyrmion bubbles.
