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Change in the direction of Early Cretaceous tectonic extension in eastern North China Craton as the result of Paleo-Pacific/Eurasian plate interaction 被引量:2
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作者 Lei Ji Jun Deng +7 位作者 Junlai Liu Xiaoyu Chen Xuefei Liu Xinmin Yang Jinlong Ni Liangliang Zhang Yu An Pengfei Tian 《Geoscience Frontiers》 2025年第1期235-248,共14页
How the subduction direction of the Paleo-Pacific plate beneath the Eurasian plate changes in the Early Cretaceous remains highly controversial due to the disappearance of the subducted oceanic plate.Intraplate deform... How the subduction direction of the Paleo-Pacific plate beneath the Eurasian plate changes in the Early Cretaceous remains highly controversial due to the disappearance of the subducted oceanic plate.Intraplate deformation structures in the east Asian continent,however,provide excellent opportunities for reconstructing paleostress fields in continental interior in relation to the Paleo-Pacific/Eurasian plate interaction.Anisotropy of magnetic susceptibility(AMS),geological,and geochronological analyses of post-kinematic mafic dykes intruding the detachment fault zone of the Wulian metamorphic core complex(WL MCC)in Jiaodong Peninsula exemplify emplacement of mantle-sourced dykes in a WNW-ESE(301°-121°)oriented tectonic extensional setting at ca.120 Ma.In combination with the results from our previous kinematic analysis of the MCC,a ca.21°clockwise change in the direction of intraplate extension is obtained for early(135-122 Ma)extensional exhumation of the MCC to late(122-108 Ma)emplacement of the dykes.Such a change is suggested to be related to the variation in subduction direction of the Paleo-Pacific plate beneath the Eurasian plate,from westward(pre-122 Ma)to west-northwestward(post-122 Ma). 展开更多
关键词 Mafic dykes Magnetic fabrics Wulian metamorphic core complex in North China Craton Tectonic extension Subduction of Paleo-Pacific plate
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Generalized Quasidiagonal Extensions of C^(*)-algebras
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作者 GAN Yuntao YAO Hongliang CHEN Peixin 《数学进展》 北大核心 2025年第6期1327-1332,共6页
This paper introduced the concept of generalized quasidiagonal extension of C^(*)-algebras and gave some basic properties.We show that the extension algebra preserves quasidiagonality and finitary in generalized quasi... This paper introduced the concept of generalized quasidiagonal extension of C^(*)-algebras and gave some basic properties.We show that the extension algebra preserves quasidiagonality and finitary in generalized quasidiagonal extension.We give also an example of generalized quasidiagonal extension,which is not quasidiagonal extension. 展开更多
关键词 C^(*)-algebra quasidiagonality generalized quasidiagonal extension
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Deformations and extensions of modified λ-differential Lie-Yamaguti algebras
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作者 TENG Wen PAN Yuewei 《中山大学学报(自然科学版)(中英文)》 北大核心 2025年第4期115-127,共13页
The modifiedλ-differential Lie-Yamaguti algebras are considered,in which a modifiedλ-differential Lie-Yamaguti algebra consisting of a Lie-Yamaguti algebra and a modifiedλ-differential operator.First we introduce t... The modifiedλ-differential Lie-Yamaguti algebras are considered,in which a modifiedλ-differential Lie-Yamaguti algebra consisting of a Lie-Yamaguti algebra and a modifiedλ-differential operator.First we introduce the representation of modifiedλ-differential Lie-Yamaguti algebras.Furthermore,we establish the cohomology of a modifiedλ-differential Lie-Yamaguti algebra with coefficients in a representation.Finally,we investigate the one-parameter formal deformations and Abelian extensions of modifiedλ-differential Lie-Yamaguti algebras using the second cohomology group. 展开更多
关键词 Lie-Yamaguti algebra modifiedλ-differential operator representation and cohomology one-parameter formal deformation Abelian extension
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Analysis of plate kinematics on the transition from diffuse to focused extension in Ross Sea basins,Antarctica
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作者 Xiaoxian Cai Jinyao Gao +2 位作者 Jie Jiang Qingsheng Guan Guochao Wu 《Acta Oceanologica Sinica》 2025年第11期141-150,共10页
The Ross Sea basins,shaped by Late Cretaceous and Cenozoic extension within the crust of the Ross Sea,represent key regions for understanding continental rifting processes.However,the dynamic mechanisms driving the tr... The Ross Sea basins,shaped by Late Cretaceous and Cenozoic extension within the crust of the Ross Sea,represent key regions for understanding continental rifting processes.However,the dynamic mechanisms driving the transition from diffuse extension to focused extension in these basins remain poorly understood.Here,we provide a comprehensive model of crustal extension in the Ross Sea basins,detailing the kinematic and dynamic evolution from 100 Ma to the present on the basis of published finite rotation poles.Our model illuminates the complex relative motions between the West Antarctic and East Antarctic Plates and quantifies the crustal strain rates associated with their relative movements.We show that West Antarctica began to move away slowly from the East Antarctic and rotated clockwise at approximately 53 Ma,and the motion progressively decreased until it ceased at approximately 11 Ma.This kinematic shift temporally coincided with the onset of focused rifting,indicating a transition from broadly distributed extension in the eastern Ross Sea to localized deformation in the western basin.Time-resolved strain rate fields further reveal several hundred kilometers of total crustal extension,suggesting a primary influence of evolving plate motions over passive lithospheric weakening.These findings refine the tectonic history of the Ross Sea and provide a reproducible framework linking rift basin evolution to global plate motion. 展开更多
关键词 Ross Sea rift basins plate kinematics crustal extension transition diffuse to ocused extension strain rates
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Photoacoustic microscopy depth-of-field extension method and system based on three-dimensional continuity and sparsity deconvolution
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作者 Tingting Li Jialin Li +2 位作者 Lingyu Ma Cheng Ma Mingjian Sun 《Journal of Innovative Optical Health Sciences》 2025年第6期27-41,共15页
Optical-resolution photoacoustic microscopy is a novel imaging technique that combines the advantages of optical and ultrasound imaging,enabling high-resolution visualization of biological tissues at the micrometer sc... Optical-resolution photoacoustic microscopy is a novel imaging technique that combines the advantages of optical and ultrasound imaging,enabling high-resolution visualization of biological tissues at the micrometer scale.However,the divergence of the excited Gaussian beam limits the depth-of-field of the system to less than 100μm,which hinders accurate three-dimensional imaging of living tissues and restrictsits applicability in biological research.Therefore,there is an urgent need for an effective method to enhance the depth-of-field without altering the hardware configuration.This paper presents a photoacoustic microscopy depth-of-field extension method and system based on three-dimensional continuity and sparsity deconvolution.This method utilizes a depth-varying point spread function and incorporates continuity and sparsity con-straints into the deconvolution process to mitigate the effect of background noise,enhancing the stability and accuracy of the depth-of-field extension.Experimental results using tungsten wire phantoms suggest that the depth-of-field of system can be extended to 650 pm,which is 7.2 times greater than conventional system,while improving the resolution of the defocused region by an average factor of 3.5.Furthermore,experiments on zebrafish and nude mouse ears with irregular topologies demonstrate that the proposed method successfully overcomes image blurring and the loss of structural information due to limited depth-of-field.All the results suggest that the system with higher lateral resolution and enhanced depth-of-field has significant potential for a wide range of practical biomedical applications. 展开更多
关键词 Photoacoustic microscopy depth-of-field extension DECONVOLUTION
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Early Paleozoic Bimodal Magmatism Documents the Transition from Collisional to Extensional Tectonics within the Central Himalaya
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作者 YIN Zhiqiang LIU Longqiang +4 位作者 LÜXiaochun LI Nan ZHU Lidong LIU Qiang HA Erjia 《Acta Geologica Sinica(English Edition)》 2025年第3期679-692,共14页
The tectonic setting of the Himalaya during the Early Paleozoic has been a subject of enduring debate within the scientific community.Newly discovered bimodal intrusive rocks from comprehensive field geological invest... The tectonic setting of the Himalaya during the Early Paleozoic has been a subject of enduring debate within the scientific community.Newly discovered bimodal intrusive rocks from comprehensive field geological investigation in the central mountain range were subjected to petrology,zircon U-Pb geochronology,zircon Hf isotopes and whole-rock geochemistry analyses.The Palie bimodal intrusive rocks,comprising amphibolite and granitic gneiss,were formed at~489 Ma.The amphibolite exhibits geochemical characteristics consistent with N-MORB,while the granitic gneiss is classified as high potassium calc-alkaline peraluminous S-type granite.Both igneous rocks exhibit negative zirconε_(Hf)(t)values and display ancient T_(DM)^(C)ages.In conjunction with regional geological survey findings,it can be inferred that the formation of the Palie bimodal intrusive rocks occurred within a post-collision extensional tectonic setting.The amphibolite genesis involved partial melting of an enriched lithospheric mantle with some crustal assimilation,whereas the origin of the granitic gneiss can be attributed to partial melting of pre-existing felsic crust.Our data indicate that during the Early Paleozoic,the Himalaya underwent a transition from a pan-African collisional setting to post-collisional extensional tectonics. 展开更多
关键词 igneous rocks TECTONICS bimodal magmatism post-collision extension ORDOVICIAN Palie
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Extensions and Deformations of 3-Lie Algebras with Higher Derivations
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作者 Shuangjian GUO 《Journal of Mathematical Research with Applications》 2025年第1期20-32,共13页
In this paper,we call a tuple consisting of 3-Lie algebra and a higher derivation on it a 3-LieHDer pair.We introduce a cohomology theory of 3-LieHDer pairs.Next,we interpret the second cohomology group as the space o... In this paper,we call a tuple consisting of 3-Lie algebra and a higher derivation on it a 3-LieHDer pair.We introduce a cohomology theory of 3-LieHDer pairs.Next,we interpret the second cohomology group as the space of all isomorphism classes of abelian extensions.Finally,we consider formal deformations of 3-LieHDer pairs that are governed by the cohomology with self-coefficient. 展开更多
关键词 higher derivations 3-LieHDer pairs COHOMOLOGY extensionS formal deformations
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Characteristics of Farmers and Extension Services Affecting the Sustainability of Seaweed Cultivation in Polewali Mandar,Indonesia
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作者 Husniah Anna Fatchiya +1 位作者 Siti Amanah Pudji Muljono 《Sustainable Marine Structures》 2025年第4期1-8,I0003,I0004,共10页
This study aimed to examine the influence of farmer characteristics and extension services on the sustainability of seaweed cultivation in three districts of Polewali Mandar Regency,West Sulawesi,namely Polewali,Binua... This study aimed to examine the influence of farmer characteristics and extension services on the sustainability of seaweed cultivation in three districts of Polewali Mandar Regency,West Sulawesi,namely Polewali,Binuang,and Wonomulyo.A total of 267 seaweed farmers were surveyed using a questionnaire,and the data were analyzed through multiple linear regression.Informed consent was obtained in writing from all participants before data collection.The results showed that farmer characteristics and extension services had a positive and significant effect on seaweed farming sustainability.These findings highlight the importance of strengthening both human capital and institutional support.Key farmer characteristics,such as education level,farming experience,motivation,and openness to innovation,play a vital role in sustaining seaweed businesses.Enhancing these competencies through training,formal and non-formal education,and capacity-building programs will improve farmers’ability to adopt sustainable practices,adapt to environmental changes,and increase productivity.Similarly,the significant role of extension services demonstrates the need for continuous technical assistance,knowledge transfer,and institutional backing.Improving extension systems by deploying more qualified field officers,conducting regular farm visits,and tailoring content to local contexts can bridge the gap between innovation and practice.Participatory extension models that engage farmers directly can further promote peer learning and community cohesion.At the policy level,this study supports integrating farmer capacity development and extension strengthening into regional agricultural and fisheries strategies to ensure long-term sustainability of seaweed farming. 展开更多
关键词 Seaweed Farmer Characteristics extension Business Sustainability
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Non-Abelian Extensions of Rota-Baxter Pre-Lie Algebras and Wells Exact Sequences
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作者 Shuangjian GUO Qun WANG 《Journal of Mathematical Research with Applications》 2025年第4期473-487,共15页
In this paper,we introduce non-abelian cohomology groups and classify the nonabelian extensions of Rota-Baxter pre-Lie algebras in terms of non-abelian cohomology groups.Next,we explore the inducibility of pairs of au... In this paper,we introduce non-abelian cohomology groups and classify the nonabelian extensions of Rota-Baxter pre-Lie algebras in terms of non-abelian cohomology groups.Next,we explore the inducibility of pairs of automorphisms and derive the analog Wells exact sequences under the circumstance of Rota-Baxter pre-Lie algebras.Finally,we discuss the inducibility problem of pairs of automorphisms about an abelian extensions of Rota-Baxter pre-Lie algebras. 展开更多
关键词 Rota-Baxter pre-Lie algebra non-abelian extension Wells exact sequences
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Energy dissipation characteristics of sandstone under triaxial extension with different confining pressures
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作者 MA Chun-de TAN Guan-shuang +2 位作者 YANG Wen-yuan KANG Zi-hao ZHANG Gui-yin 《Journal of Central South University》 2025年第6期2195-2207,共13页
After excavation,some of the surrounding rock mass is in a state of triaxial extension,exhibiting tensile or shear fracture modes.To study the energy mechanism of tensile fracture turning to shear fracture,a series of... After excavation,some of the surrounding rock mass is in a state of triaxial extension,exhibiting tensile or shear fracture modes.To study the energy mechanism of tensile fracture turning to shear fracture,a series of triaxial extension tests were conducted on sandstone under confining pressures of 10,30,50 and 70 MPa.Elastic energy and dissipated energy were separated by single unloading,the input energy u_(t),elastic energy u_(e),and dissipated energy u_(d)at different unloading stress levels were calculated by the integrating stress−strain curves.The results show that tensile cracks dominate fracture under lower confining pressure(10 MPa),and shear cracks play an increasingly important role in fracture as confining pressure increases(30,50 and 70 MPa).Based on the phenomenon that u_(e)and u_(d)increase linearly with increasing u_(t),a possible energy distribution mechanism of fracture mode transition under triaxial extension was proposed.In addition,it was found that peak energy storage capacity is more sensitive to confining pressure compared to elastic energy conversion capacity. 展开更多
关键词 triaxial extension energy distribution fracture mode energy dissipation energy storage
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Sea level prediction in the Kuroshio Extension region using ConvLSTM with wind-driven physical constraints
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作者 Duotian Huang Xuhua Cheng 《Acta Oceanologica Sinica》 2025年第12期100-112,共13页
In this study,convolutional long short-term memory(ConvLSTM)model is used to predict sea level anomaly(SLA)in the Kuroshio Extension(KE)region,utilizing daily satellite altimetry data(1993-2016).The model captures reg... In this study,convolutional long short-term memory(ConvLSTM)model is used to predict sea level anomaly(SLA)in the Kuroshio Extension(KE)region,utilizing daily satellite altimetry data(1993-2016).The model captures regional averaged SLA variability,achieving a correlation coefficient of 0.98 for prediction horizon up to 23 d.Propagating features of Rossby waves are also reproduced in the prediction model.While in spatial,discrepancies between predicted SLA and observed SLA are quite large,especially in regions with strong eddy activities.Incorporating equation of motion for the 11/2-layer reduced-gravity model,the performance of the model has a significant improvement spatially and temporally.Challenges persist in high-variability regions,underscoring the need for advanced models.This study highlights ConvLSTM’s potential for SLA forecasting with wind driven physical constraints,offering insights into wind-driven and eddy-influenced processes in the KE region. 展开更多
关键词 sea level prediction wind stress Kuroshio extension deep learning convolutional LSTM
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Performance evaluation of sponge city PPP projects using improved matter-element extension method
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作者 CHEN Zhi-ding HU Min-qian 《Ecological Economy》 2025年第2期151-168,共18页
Sponge city(SPC)is proposed to solve the issues such as the degradation of urban water ecosystem environment,imbalanced water resource allocation,urban water logging,and water contamination.The PPP(Public Private Part... Sponge city(SPC)is proposed to solve the issues such as the degradation of urban water ecosystem environment,imbalanced water resource allocation,urban water logging,and water contamination.The PPP(Public Private Partnership)model is combined to release the government pressure of SPC project construction.The development of the SPC-PPP model makes significant contributions to the sustainable development and the enhancement of urban resilience against water-related disasters.However,there is no scientific performance evaluation system on its operation period has been conducted.Therefore,the SPC-PPP Evaluation model aims to objectively and reasonably assess project effectiveness,promote its development and refine the evaluation framework.This paper has set up the MEE model for performance evaluation,with improved Matter-Element Extension method to assign values to the evaluation indices.The research results show that:(1)The MEE model is more accurate in the performance evaluation and its effectiveness is reflected in its ability to capture the correlation among different indices in the same membership,rather than merely focusing on individual indices.(2)The proposed approach provided a new aspect for performance evaluation,improving the accuracy of evaluation and promoting the development of SPC-PPP project. 展开更多
关键词 public private partnership sponge city performance evaluation improved matter-element extension method
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Generation of multitype,multicavity chaotic attractors via impulse-function-based state variable extension
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作者 Xiaoyu Hu Siteng Wang +3 位作者 Panpan Wu Hongbo Cao Tianwei Yang Zhongshuo Dong 《Chinese Physics B》 2025年第8期506-516,共11页
This paper proposes a universal impulse-function-based method for extending discrete chaotic maps,enabling flexible construction of multicavity chaotic attractors.The proposed method achieves one-directional(1D)/two-d... This paper proposes a universal impulse-function-based method for extending discrete chaotic maps,enabling flexible construction of multicavity chaotic attractors.The proposed method achieves one-directional(1D)/two-directional(2D)extensions without introducing additional nonlinear terms or altering system stability.Theoretically,the cavity quantity in arbitrary directions is controlled by adjusting impulse levels N,while the amplitude regulation is implemented through modifications to the proportionality parameter r.Theoretical analyses,including Lyapunov exponents(LEs)and bifurcation diagrams,are conducted,confirming that the extended maps retain the intrinsic dynamics of five rational map classes.The field-programmable gate array(FPGA)implementation results are consistent with the numerical simulation results,verifying the correctness of the theoretical analysis.The method enables the expansion of unipolar attractors and enhances entropy metrics,offering a robust framework for applications in secure communication,encryption,and chaos-based technologies. 展开更多
关键词 discrete chaotic maps impulse-function-based extension method discrete multicavity attractors FPGA implementation
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LOCALLY QUASIDIAGONAL EXTENSIONS OF C^(*)-ALGEBRAS
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作者 SHI Chang-li YAO Hong-liang 《数学杂志》 2025年第6期485-492,共8页
This paper introduce the concept of locally quasidiagonal extension of C^(*)-algebras and give some basic properties.We use the method of analogy,based on some properties possessed by quasidiagonal extensions,we inves... This paper introduce the concept of locally quasidiagonal extension of C^(*)-algebras and give some basic properties.We use the method of analogy,based on some properties possessed by quasidiagonal extensions,we investigate whether local quasidiagonal extensions still retain these properties.We then show that an extension of a locally AF algebra by a locally AF algebra is a locally quasidiagonal extension. 展开更多
关键词 C^(*)-algebra quasidiagonal C^(*)-algebra locally quasidiagonal extension
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Oceanic Eddy Kinetic Energy in the Spectral Space Regulated by Mesoscale Air–Sea Heat Exchange in the Kuroshio Extension
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作者 Mingkui LI Jinzhuo CAI +2 位作者 Haiyuan YANG Zhaohui CHEN Lixin WU 《Advances in Atmospheric Sciences》 2025年第12期2539-2549,共11页
Mesoscale air-sea interactions play a critical role in damping eddy activities.However,how mesoscale heat flux influences the distribution of eddy kinetic energy(EKE)in the wavenumber space remains unclear.In this stu... Mesoscale air-sea interactions play a critical role in damping eddy activities.However,how mesoscale heat flux influences the distribution of eddy kinetic energy(EKE)in the wavenumber space remains unclear.In this study,we investigate the EKE and temperature variance(T_(var))budgets in the Kuroshio Extension(KE)region using wavenumber spectral analysis based on 1/10°coupled climate simulations.These simulations include a standard high-resolution simulation and a smoothed simulation that overlooks mesoscale heat flux.By comparing the differences between these models,we confirm that air-sea heat exchange significantly dissipates Tvar.Neglecting mesoscale heat flux results in a 60% underestimation of the Tvar damping rate,which in turn increases energy transfer to EKE through the vertical buoyancy flux by 22%.This enhanced vertical buoyancy flux leads to a 20% higher EKE level and larger energy budget terms,particularly in the diffusion term,which is closely related to wind power.Furthermore,underestimating air-sea heat exchange could lead to an overestimation of the inverse kinetic energy cascade,thereby distorting the overall energy budget in the KE region. 展开更多
关键词 air-sea heat exchange mesoscale eddy spectral analysis energy budget energy cascade Kuroshio extension
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Enhancing climate-smart coastal farming system through agriculture extension and advisory services towards the avenues of farm sustainability
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作者 Md Maruf BILLAH Mohammad Mahmudur RAHMAN +3 位作者 Santiago MAHIMAIRAJA Alvin LAL Asadi SRINIVASULU Ravi NAIDU 《Regional Sustainability》 2025年第4期12-25,共14页
Agriculture extension and advisory services(AEAS)are integral to smart agricultural systems and play a pivotal role in supporting sustainable agricultural development.The study aimed to assess the role of AEAS in stre... Agriculture extension and advisory services(AEAS)are integral to smart agricultural systems and play a pivotal role in supporting sustainable agricultural development.The study aimed to assess the role of AEAS in strengthening climate-smart coastal farming system to enhance coastal agricultural sustainability.A mixed-methods study was conducted in the southwestern coastal region of Bangladesh in 2023,which involved administering a structured questionnaire and conducing face-to-face interviews with 390 farmers.Perceived role index(PRI)was employed to assess the potential role of AEAS.To forecast the perceived role outcomes,the machine learning model was undertaken by utilizing suitable algorithms.Additionally,feature importance was calculated to underpin the significant factors of perceived role outcomes.The findings showed that coastal farming communities held a comprehensive understanding of the role of AEAS.Key roles included diffusion of agricultural innovations,acting as a bridge between farmers and research organizations,using demonstration techniques to educate farmers,training farmers on food storage,processing,and utilization,and promoting awareness and adoption of best practices.The machine learning model exposed a significant relationship between farmers’socio-economic characteristics and their perception behavior.The results identified that factors like innovativeness,awareness,training exposure,access to AEAS,and access to information significantly influenced how farmers perceived the efficacy of AEAS in promoting a smart coastal farming system.However,farmers confronted multiple constraints in receiving demand-driven services and maintaining coastal farm sustainability.These insights can guide concerned authorities and policy-makers in providing AEAS for the purpose of strengthening climate-smart coastal farming system,particularly with a special focus on capacity building programs and machine learning application.Moreover,the outcomes of this study can assist the authorities of similar coastal systems throughout the world to initiate potential strategies for enhancing region-specific agricultural sustainability. 展开更多
关键词 Agriculture extension and advisory services(AEAS) Climate-smart coastal farming system Climate change Machine learning Farm sustainability
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大尺寸真三轴煤岩复合体水力压裂模拟实验的教学实践
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作者 李波 王凯 +1 位作者 魏建平 张飞燕 《实验室研究与探索》 北大核心 2026年第2期160-165,188,共7页
水力压裂作为煤岩增透技术,已成功应用于煤层气开发,其通过建立水力缝网为瓦斯迁移提供通道,实现增透效果。为帮助学生更直观地认识煤岩体中裂缝的扩展过程,研究构建了基于真三轴物理模拟实验的教学创新体系。以煤-岩复合体为实验对象,... 水力压裂作为煤岩增透技术,已成功应用于煤层气开发,其通过建立水力缝网为瓦斯迁移提供通道,实现增透效果。为帮助学生更直观地认识煤岩体中裂缝的扩展过程,研究构建了基于真三轴物理模拟实验的教学创新体系。以煤-岩复合体为实验对象,依托自主研发的真三轴煤岩体水力压裂渗流试验系统,开展水力压裂模拟试验。通过在压裂液中添加示踪剂,并结合声发射装置监测煤岩体破裂源,系统研究裂缝起裂、扩展与贯通规律,以揭示岩体裂隙扩展机理。该实验体系通过理论与物理实验的深度融合,形成“理论—实验”全链条教学范式,旨在培养学生的专业技能、创新思维及解决实际工程问题的能力,不仅实现了教学内容与行业前沿技术的同步,也为行业培养高素质专业人才提供了支撑。 展开更多
关键词 水力压裂 裂缝扩展 真三轴 声发射监测 实验教学
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伸展盆地中的变换走滑构造及其油气地质意义
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作者 刘晓林 景安语 +1 位作者 武云云 李伟 《海洋地质前沿》 北大核心 2026年第1期11-24,共14页
变换构造在伸展盆地内普遍发育,变换走滑构造作为其中的一种特殊类型,是为保持区域或局部应变守恒、传递伸展断层之间的位移,发育在不同伸展断层域之间的具有明显水平位移的被动走滑构造,形成于非走滑应力体制下。变换走滑构造在中国东... 变换构造在伸展盆地内普遍发育,变换走滑构造作为其中的一种特殊类型,是为保持区域或局部应变守恒、传递伸展断层之间的位移,发育在不同伸展断层域之间的具有明显水平位移的被动走滑构造,形成于非走滑应力体制下。变换走滑构造在中国东部伸展盆地中普遍发育、类型多样,依据是否形成明显的走滑断裂可划分为变换走滑断层和变换走滑带,其类型与两侧断层伸展差异大小有关,进一步依据两侧断层的倾向,每类又可划分为倾向相反型、倾向相同型和倾向复杂型3个亚类。变换走滑构造对油气成藏具有重要的控制作用,可以为伸展盆地内构造圈闭解释判识提供依据,变换走滑构造导致局部地层的弯曲变形,控制了古地貌或微古地貌的分布,进而对沉积储层的发育展布具有一定的控制作用;变换走滑构造可以作为有利的油气聚集区带,也可以对油气分布起到分隔作用。 展开更多
关键词 变换走滑构造 类型划分 控藏作用 伸展盆地
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亏损结转年限延长影响审计收费吗?
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作者 冉明东 康海南 王成龙 《审计研究》 北大核心 2026年第1期104-116,共13页
作为重要的宏观制度安排,税收制度变革不仅直接影响企业的投资与经营行为,也可能影响资本市场中审计服务的定价机制。本文以2018年实施的亏损结转年限延长政策为准自然实验,以2012—2023年我国A股上市公司为研究对象,构建双重差分模型... 作为重要的宏观制度安排,税收制度变革不仅直接影响企业的投资与经营行为,也可能影响资本市场中审计服务的定价机制。本文以2018年实施的亏损结转年限延长政策为准自然实验,以2012—2023年我国A股上市公司为研究对象,构建双重差分模型考察亏损结转年限延长政策对审计收费的影响。研究发现,亏损结转年限延长会显著提高审计收费。机制分析表明,上述结果主要通过影响审计师感知到的业务风险和审计风险从而推高了审计收费的风险溢价。此外,异质性分析发现,亏损结转年限延长对审计收费的正向影响在融资约束较低、代理成本较高以及审计师具有行业专长的企业中更为显著。本文将亏损结转年限延长政策的经济后果研究从企业拓展至审计师这一外部利益相关者,为政府更加全面地评估政策后果提供了理论参考。 展开更多
关键词 亏损结转年限延长 审计收费 业务风险 审计风险
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柔性刀具冲击破煤应力场演化及裂纹扩展规律
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作者 魏建平 郜英俊 +5 位作者 徐向宇 陈长江 张慧栋 刘勇 刘昊 谢鹏 《煤炭学报》 北大核心 2026年第1期497-511,共15页
柔性刀具扩孔是煤层卸压增透的新式技术手段,为解决现阶段柔性刀具破煤能力不足难题,基于动能一定的前提条件下,通过优化柔性刀具结构参数提高破煤性能。为此,建立了二维柔性刀具破煤数值模型,明确了破煤过程煤体应力场演化和裂纹扩展特... 柔性刀具扩孔是煤层卸压增透的新式技术手段,为解决现阶段柔性刀具破煤能力不足难题,基于动能一定的前提条件下,通过优化柔性刀具结构参数提高破煤性能。为此,建立了二维柔性刀具破煤数值模型,明确了破煤过程煤体应力场演化和裂纹扩展特征,从细观尺度研究不同安装角度、刀齿数量和刀齿间距对煤体应力演化和裂纹发育规律的影响,明确了动能统一条件下刀齿数量对煤体破坏过程能量演化规律的影响,揭示了安装角度和刀齿间距对煤体裂纹扩展影响机制。结果表明:煤体应力波受刀齿安装角度影响表现为不规则传播,安装角度为0°~20°时为冲击破煤,中间裂纹和侧向裂纹以冲击点为中心向周围辐射,裂纹数量分布均匀;安装角度为25°~40°时为冲击-磨削破煤,冲击作用占主导地位,侧向裂纹发育,刀齿载荷出现双峰值,安装角度35°时破碎面积最大;在动能一定条件下,随着刀齿数量增加能量转化时间缩短、煤体破碎面积增大,双刀齿冲击煤体应变能峰值和应变能集中程度更高,更利于裂隙的快速发育和连通;双刀齿冲击在煤体内部形成连通弧形压应力区,2个冲击点之间力链相互沟通为颗粒间裂隙形成提供前提条件,进而提高煤体破坏效果;存在最优刀齿安装角度,能够改善力的传递效果使煤体破碎面积最大,存在最优刀齿间距,使破碎区域相互连通,充分发挥双刀齿协同破煤作用。 展开更多
关键词 卸压增透 柔性刀具 冲击破煤 应力演化 裂纹扩展
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