In this article,the authors introduce the concept of shadowable points for set-valued dynamical systems,the pointwise version of the shadowing property,and prove that a set-valued dynamical system has the shadowing pr...In this article,the authors introduce the concept of shadowable points for set-valued dynamical systems,the pointwise version of the shadowing property,and prove that a set-valued dynamical system has the shadowing property iff every point in the phase space is shadowable;every chain transitive set-valued dynamical system has either the shadowing property or no shadowable points;and for a set-valued dynamical system there exists a shadowable point iff there exists a minimal shadowable point.In the end,it is proved that a set-valued dynamical system with the shadowing property is totally transitive iff it is mixing and iff it has the specification property.展开更多
The authors introduce the concepts of the eventual shadowing property and eventually shadowable point for set-valued dynamical systems and prove that a set-valued dynamical system has the eventual shadowing property i...The authors introduce the concepts of the eventual shadowing property and eventually shadowable point for set-valued dynamical systems and prove that a set-valued dynamical system has the eventual shadowing property if and only if every point in the phase space is eventually shadowable;every chain transitive set-valued dynamical system has either the eventual shadowing property or no eventually shadowable points;and a set-valued dynamical system admits an eventually shadowable point if and only if it admits a minimal eventually shadowable point.Moreover,it is proved that a set-valued dynamical system with the eventual shadowing property is chain mixing if and only if it is mixing and if and only if it has the specification property.展开更多
We prove that the set of vector fields satisfying the C1 stable shadowable property on closed surfaces is characterized as the set of Morse-Smale vector fields. Hence, the vector fields satisfying shadowing property o...We prove that the set of vector fields satisfying the C1 stable shadowable property on closed surfaces is characterized as the set of Morse-Smale vector fields. Hence, the vector fields satisfying shadowing property on closed surfaces are C1 dense.展开更多
Before joining the Beijing Dragon Shadow Puppetry Art Theatre,this group of young people rarely had the chance to meet people like themselves,lacked friends,faced obstacles at work,and felt alienated from society.Now,...Before joining the Beijing Dragon Shadow Puppetry Art Theatre,this group of young people rarely had the chance to meet people like themselves,lacked friends,faced obstacles at work,and felt alienated from society.Now,they have gained appreciation,recognition,confidence,friendships,and love.展开更多
We prove that any C1-stable weakly shadowable volume-preserving diffeomorphism defined on a compact manifold displays a dominated splitting E ⊕ F. Moreover, both E and F are volume-hyperbolic. Finally, we prove the v...We prove that any C1-stable weakly shadowable volume-preserving diffeomorphism defined on a compact manifold displays a dominated splitting E ⊕ F. Moreover, both E and F are volume-hyperbolic. Finally, we prove the version of this result for divergence-free vector fields. As a consequence, in low dimensions, we obtain global hyperbolicity.展开更多
As Artificial Intelligence(AI)is moving fast from Large Language Models(LLMs)to AI Agents and Agentic Intelligence,the need to incorporate new AI into Decision Intelligence(DI)is becoming more and more urgent for both...As Artificial Intelligence(AI)is moving fast from Large Language Models(LLMs)to AI Agents and Agentic Intelligence,the need to incorporate new AI into Decision Intelligence(DI)is becoming more and more urgent for both practical and theoretic reasons:both decision and process complexities would be significantly increased due to the use of advanced AI tools and agents,and both traditional and recent thinking must be rethought and reconstructed accordingly.Our perspective would like to address this important issue based on some historical milestone developments in Computer-Aided Software Engineering(CASE)and recent efforts in digital theatrical technology[1].展开更多
Digital twin(DT)technology has been utilised in many applications including electric vehicles(EVs).A DT is a virtual representation of a physical object,enabled through real-time data integration,simulation,and optimi...Digital twin(DT)technology has been utilised in many applications including electric vehicles(EVs).A DT is a virtual representation of a physical object,enabled through real-time data integration,simulation,and optimisation tools.Unlike conventional simulations,which are typically offline and lack real-time interaction,a DT continuously synchronises with the physical system,enabling dynamic performance monitoring and predictive an-alytics.Achieving a full DT involves progressive stages,with the digital shadow(DS)being the final step before realising a bidirectional DT.Building a DS provides a scalable real-time performance monitoring and fault detection framework,enabling proactive decision-making in EV operations.This study introduces a DS system specifically designed to monitor the performance of a permanent magnet synchronous motor(PMSM)drive system in EVs,marking a critical phase towards a complete DT.The methodology for creating the DS is detailed,including the establishment of a compre-hensive test bench for the EV powertrain as the physical reference model.The mathe-matical model of the EV-PMSM was formulated,and an advanced estimation model utilising the extended Kalman filter(EKF)was implemented.MATLAB/Simulink was employed to develop the motor’s digital model.Real-time data acquisition from the physical model was facilitated through a data acquisition system(DAS)equipped with a controller area network(CAN)communication interface.The digital model underwent thorough validation against sensory data collected from the test bench.The motor digital model was deployed to a DS framework enabled through real-time data flow from the actual EV during real-world driving conditions.The results demonstrated a high accuracy of 97%between the DS predictions and the corresponding EV data,confirming the DS’s reliability.These findings pave the way for future advancements,including bidirectional interaction and the realisation of a full DT.展开更多
This study compares Confucian sincerity(cheng)and Jungian individuation as two paths toward authentic selfhood.Confucian sincerity stresses aligning inner intention with outward action,while Jungian individuation emph...This study compares Confucian sincerity(cheng)and Jungian individuation as two paths toward authentic selfhood.Confucian sincerity stresses aligning inner intention with outward action,while Jungian individuation emphasizes integrating persona and shadow.The paper argues that both traditions describe a shared developmental pattern:authenticity emerges when individuals confront inner contradictions,cultivate honest self-awareness,and reduce the gap between internal and external selves.展开更多
This review takes stock of China’s Double Reduction.In the short run,it lowered visible burden and pushed demand from subject tutoring toward on-campus and non-subject services.But with high-stakes selection unchange...This review takes stock of China’s Double Reduction.In the short run,it lowered visible burden and pushed demand from subject tutoring toward on-campus and non-subject services.But with high-stakes selection unchanged,demand reappears as small-group/one-to-one provision,advantaging families with high socioeconomic status and strong schools.Lasting relief will require tighter oversight and admissions reform with targeted,well-funded in-school support.展开更多
China’s night fairs,combining history with food and adventure,are what you need to unwind after a hard day’s work.I have lived in China for several years,and visiting night fairs has become a part of my life.In Beij...China’s night fairs,combining history with food and adventure,are what you need to unwind after a hard day’s work.I have lived in China for several years,and visiting night fairs has become a part of my life.In Beijing,I often go to Guijie on weekends to discover new things.It’s a historical place with an enticing old name:Ghost Street.I am told this used to be a popular market in the Qing Dynasty(1644-1911)and the oil lamps used in the stalls,giving a dim light and casting long shadows,made it look so eerie that people began to call it the Ghost Street.展开更多
In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the...In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the DM halo parameter and the cloud string parameter affect BH attributes such as quasinormal modes(QNMs)and shadow cast.To do this,we first look into the effective potential of perturbation equations for three types of perturbation fields with different spins:massless scalar field,electromagnetic field and gravitational field.Then,using the sixth-order Wentzel-Kramers-Brillouin approximation,we examine QNMs of the BH disturbed by the three fields and derive quasinormal frequencies.The changes in QNM versus the core density parameter and the cloud string parameter for three disturbances are explored.We also investigate how the core density and the cloud string parameter affect the photon sphere and shadow radius.Interestingly,the study shows that the influence of Dehnen-type DM and cloud strings increases both the photon sphere and the shadow radius.Finally,we employ observational data from Sgr A^(*) and M87^(*) to set limitations on the BH parameters.展开更多
Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,i...Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,in particular reduction-oxidation processes that diff er from those in illuminated regions.To determine the characteristics of products formed during space weathering in PSRs,the lunar meteorite NWA 10203 with artifi cially added water was irradiated with a nanosecond laser to simulate a micro-meteorite bombardment of lunar soil containing water ice.The TEM results of the water-incorporated sample showed distinct amorphous rims that exhibited irregular thickness,poor stratifi cation,the appearance of bubbles,and a reduced number of npFe^(0).Additionally,EELS analysis showed the presence of ferric iron at the rim of the nanophase metallic iron particles(npFe^(0))in the amorphous rim with the involvement of water.The results suggest that water ice is another possible factor contributing to oxidation during micrometeorite bombardment on the lunar surface.In addition,it off ers a reference for a new space weathering model that incorporates water in PSRs,which could be widespread on asteroids with volatiles.展开更多
During multi-cluster fracturing of horizontal wells,low-viscosity fracturing fluid permeates extensively along the fracture walls into the rock pores,exerting seepage forces on the rock skeleton.However,the mechanism ...During multi-cluster fracturing of horizontal wells,low-viscosity fracturing fluid permeates extensively along the fracture walls into the rock pores,exerting seepage forces on the rock skeleton.However,the mechanism of how seepage forces influence multi-cluster fracture propagation behavior remains unclear.In this study,we analyze the response relationship between the pore pressure field and the seepage field under transient seepage conditions.We established a numerical simulation model of multi-cluster fracture propagation in horizontal wells considering seepage forces based on the discrete element particle flow method.Using this model,we examined the mechanisms by which seepage forces affect the dynamic evolution of the induced stress field and fracture propagation behavior under various combinations of fracturing fluid viscosity,injection rate,in-situ stress,and cluster spacing.Numerical simulation results indicate that the infiltration of fracturing fluid into rock pores and the resulting seepage forces significantly alter the propagation patterns of inter-cluster fractures and the distribution of the induced stress field.Under the influence of seepage forces,hydraulic fractures suppressed by stress shadows are redirected and captured by adjacent fractures.Selecting appropriate fracturing fluid viscosity and injection rate can effectively utilize seepage forces to mitigate the inhibitory effects of the high compressive stress zones within stress shadows on intermediate fracture propagation,thereby increasing the likelihood of inter-fracture communication and the formation of a complex fracture network.This study not only underscores the importance of considering seepage forces in the design of multi-stage fracturing treatments but also provides critical theoretical insights for optimizing fracturing operation parameters.展开更多
Goh Boon Teck is the chief artistic director of Toy Factory,a Singaporean theater company founded in 1990.According to Goh,a group of young people decided to organize their own theater company due to a love for drama....Goh Boon Teck is the chief artistic director of Toy Factory,a Singaporean theater company founded in 1990.According to Goh,a group of young people decided to organize their own theater company due to a love for drama.The“Toy”in the name of the theater company comes from a Thai shadow puppet artist who worked with them,and“Factory”highlights the organization’s devotion to training theater practitioners for the art community.Goh said that in addition to staging productions,Toy Factory has also vigorously worked to discover new drama artists including actors,designers,and playwrights.展开更多
Verlinde's emergent gravity(VEG)posits that gravity arises as an emergent phenomenon rooted in the entropic properties of spacetime,challenging the traditional view of gravity as a fundamental force.Building on th...Verlinde's emergent gravity(VEG)posits that gravity arises as an emergent phenomenon rooted in the entropic properties of spacetime,challenging the traditional view of gravity as a fundamental force.Building on this paradigm,recent developments have introduced a novel class of black holes within the VEG framework,revealing intriguing connections between apparent dark matter effects and the distribution of baryonic matter.In this study,we delve into the observational signatures of a Simpson–Visser(SV)Minkowski core regular black hole in VEG,focusing on its shadow images and intensity profiles.Our analysis highlights the profound influence of model parameters,including A(governing baryonic matter distribution),B(strength of interaction between apparent dark matter and baryonic matter),and n(characterizing diverse spacetime geometries),on the effective potential and observable properties.Notably,we find that the modifications introduced by these parameters lead to distinct changes in the black hole's shadow size and intensity distribution.Comparing our results to the Reissner–Nordström(RN)black hole,we uncover a striking reduction in the apparent shadow size and an enhancement in intensity for the SV solution in VEG.展开更多
The marginal abatement cost(MAC)of CO_(2)emissions is one of the most critical indicators used to assess energy conservation and emission reduction.Although extensively measured,few studies have incorporated the influ...The marginal abatement cost(MAC)of CO_(2)emissions is one of the most critical indicators used to assess energy conservation and emission reduction.Although extensively measured,few studies have incorporated the influence of policy constraints when evaluating MAC.To address this gap,this paper proposes a nonparametric directional distance function approach under policy regulations to estimate the CO_(2)shadow price in the construction industry across 30 Chinese provinces from 2010 to 2017.Based on this enhanced method,four key findings emerge:①the annual CO_(2)shadow price exhibits an overall upward trend during the observation period;②regional shadow prices display marked variation across provinces;③regional heterogeneity in shadow prices has increased steadily over time;and④both urbanization rate and energy consumption per unit of gross domestic product are significantly negatively correlated with the CO_(2)shadow price.Finally,the paper offers several policy recommendations for CO_(2)emissions reduction in the Chinese construction industry at the national,industry,and enterprise levels.展开更多
Accurate fingertip detection is critical for translating hand gestures into actionable commands in vision-based human‒computer interaction(HCI)systems.However,challenges such as complex backgrounds,dynamic hand postur...Accurate fingertip detection is critical for translating hand gestures into actionable commands in vision-based human‒computer interaction(HCI)systems.However,challenges such as complex backgrounds,dynamic hand postures,and real-time processing constraints hinder reliable detection.This paper introduces a robust framework integrating three key innovations:(1)an adaptive Gaussian mixture model(GMM)enhanced with neighborhood pixel connectivity for precise motion extraction;(2)a weighted YCbCr color-space shadow removal algorithm to eliminate false positives;and(3)a centroid distance method refined with circularity constraints for accurate fingertip localization.Extensive experiments demonstrate a recognition accuracy of 97.26%across diverse scenarios,including varying illuminations,occlusions,and hand rotations.The algorithm processes each frame in 23.43 ms on average,satisfying real-time requirements.Comparative evaluations against state-of-the-art methods reveal significant improvements in precision(8.3%),recall(6.1%),and F-measure(7.8%).This work advances HCI applications such as virtual keyboards,gesture-controlled interfaces,and augmented reality systems.展开更多
In this paper,we investigate the optical properties of a non-rotating charged black hole(BH)in the Einstein-Maxwell-scalar(EMS)theory,together with a plasma medium.We first consider the photon sphere and shadow radius...In this paper,we investigate the optical properties of a non-rotating charged black hole(BH)in the Einstein-Maxwell-scalar(EMS)theory,together with a plasma medium.We first consider the photon sphere and shadow radius under the impact of the plasma medium existing in the environment surrounding the BH in the EMS theory.We show that the radius of the photon sphere and the BH shadow decrease under the influence of the parameterβ.We further study gravitational weak lensing in detail by adapting general methods and derive the light ray's deflection angle around the BH together with the plasma environment.It is found that for uniform plasma,the deflection angle increases with the rise of the plasma parameter,whereas it decreases with the increase of the plasma parameter for non-uniform plasma.Besides,we also study the magnification of image brightness.展开更多
基金Supported by the National Natural Science Foundation of China(Grant Nos.11661054,11261039)。
文摘In this article,the authors introduce the concept of shadowable points for set-valued dynamical systems,the pointwise version of the shadowing property,and prove that a set-valued dynamical system has the shadowing property iff every point in the phase space is shadowable;every chain transitive set-valued dynamical system has either the shadowing property or no shadowable points;and for a set-valued dynamical system there exists a shadowable point iff there exists a minimal shadowable point.In the end,it is proved that a set-valued dynamical system with the shadowing property is totally transitive iff it is mixing and iff it has the specification property.
基金Supported by the National Natural Science Foundation of China(Grant Nos.12061043,11661054,11261039)。
文摘The authors introduce the concepts of the eventual shadowing property and eventually shadowable point for set-valued dynamical systems and prove that a set-valued dynamical system has the eventual shadowing property if and only if every point in the phase space is eventually shadowable;every chain transitive set-valued dynamical system has either the eventual shadowing property or no eventually shadowable points;and a set-valued dynamical system admits an eventually shadowable point if and only if it admits a minimal eventually shadowable point.Moreover,it is proved that a set-valued dynamical system with the eventual shadowing property is chain mixing if and only if it is mixing and if and only if it has the specification property.
基金Supported by National Natural Science Foundation of China (Grant No. 10871019)
文摘We prove that the set of vector fields satisfying the C1 stable shadowable property on closed surfaces is characterized as the set of Morse-Smale vector fields. Hence, the vector fields satisfying shadowing property on closed surfaces are C1 dense.
文摘Before joining the Beijing Dragon Shadow Puppetry Art Theatre,this group of young people rarely had the chance to meet people like themselves,lacked friends,faced obstacles at work,and felt alienated from society.Now,they have gained appreciation,recognition,confidence,friendships,and love.
基金supported by National Funds through FCT-"Fundao para a Ciênciae a Tecnologia"(Grant No.PEst-OE/MAT/UI0212/2011)supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science and Technology,Korea(Grant No.2011-0007649)
文摘We prove that any C1-stable weakly shadowable volume-preserving diffeomorphism defined on a compact manifold displays a dominated splitting E ⊕ F. Moreover, both E and F are volume-hyperbolic. Finally, we prove the version of this result for divergence-free vector fields. As a consequence, in low dimensions, we obtain global hyperbolicity.
基金supported by the Science and Technology Development Fund,Macao Special Administrative Region(SAR)(0093/2023/RIA2,0157/2024/RIA2,0145/2023/RIA3)the Distinguished Program of Obuda University and the DeSci Center for Parallel Intelligence at the Obuda University,Hungary.This article is based on the report of“Digital Theaters and Theatrical Intelligence for Decision Science”Project(DeSCII-0017-1023-2023,PI:Qinghua Ni)initiated by DeSci International.
文摘As Artificial Intelligence(AI)is moving fast from Large Language Models(LLMs)to AI Agents and Agentic Intelligence,the need to incorporate new AI into Decision Intelligence(DI)is becoming more and more urgent for both practical and theoretic reasons:both decision and process complexities would be significantly increased due to the use of advanced AI tools and agents,and both traditional and recent thinking must be rethought and reconstructed accordingly.Our perspective would like to address this important issue based on some historical milestone developments in Computer-Aided Software Engineering(CASE)and recent efforts in digital theatrical technology[1].
基金Estonian Research Competency Council,Grant/Award Number:PSG453,Eesti Teadusagentuur。
文摘Digital twin(DT)technology has been utilised in many applications including electric vehicles(EVs).A DT is a virtual representation of a physical object,enabled through real-time data integration,simulation,and optimisation tools.Unlike conventional simulations,which are typically offline and lack real-time interaction,a DT continuously synchronises with the physical system,enabling dynamic performance monitoring and predictive an-alytics.Achieving a full DT involves progressive stages,with the digital shadow(DS)being the final step before realising a bidirectional DT.Building a DS provides a scalable real-time performance monitoring and fault detection framework,enabling proactive decision-making in EV operations.This study introduces a DS system specifically designed to monitor the performance of a permanent magnet synchronous motor(PMSM)drive system in EVs,marking a critical phase towards a complete DT.The methodology for creating the DS is detailed,including the establishment of a compre-hensive test bench for the EV powertrain as the physical reference model.The mathe-matical model of the EV-PMSM was formulated,and an advanced estimation model utilising the extended Kalman filter(EKF)was implemented.MATLAB/Simulink was employed to develop the motor’s digital model.Real-time data acquisition from the physical model was facilitated through a data acquisition system(DAS)equipped with a controller area network(CAN)communication interface.The digital model underwent thorough validation against sensory data collected from the test bench.The motor digital model was deployed to a DS framework enabled through real-time data flow from the actual EV during real-world driving conditions.The results demonstrated a high accuracy of 97%between the DS predictions and the corresponding EV data,confirming the DS’s reliability.These findings pave the way for future advancements,including bidirectional interaction and the realisation of a full DT.
文摘This study compares Confucian sincerity(cheng)and Jungian individuation as two paths toward authentic selfhood.Confucian sincerity stresses aligning inner intention with outward action,while Jungian individuation emphasizes integrating persona and shadow.The paper argues that both traditions describe a shared developmental pattern:authenticity emerges when individuals confront inner contradictions,cultivate honest self-awareness,and reduce the gap between internal and external selves.
文摘This review takes stock of China’s Double Reduction.In the short run,it lowered visible burden and pushed demand from subject tutoring toward on-campus and non-subject services.But with high-stakes selection unchanged,demand reappears as small-group/one-to-one provision,advantaging families with high socioeconomic status and strong schools.Lasting relief will require tighter oversight and admissions reform with targeted,well-funded in-school support.
文摘China’s night fairs,combining history with food and adventure,are what you need to unwind after a hard day’s work.I have lived in China for several years,and visiting night fairs has become a part of my life.In Beijing,I often go to Guijie on weekends to discover new things.It’s a historical place with an enticing old name:Ghost Street.I am told this used to be a popular market in the Qing Dynasty(1644-1911)and the oil lamps used in the stalls,giving a dim light and casting long shadows,made it look so eerie that people began to call it the Ghost Street.
基金supported by the National Natural Science Foundation of China under Grant No.11675143the National Key Research and Development Program of China under Grant No.2020YFC2201503。
文摘In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the DM halo parameter and the cloud string parameter affect BH attributes such as quasinormal modes(QNMs)and shadow cast.To do this,we first look into the effective potential of perturbation equations for three types of perturbation fields with different spins:massless scalar field,electromagnetic field and gravitational field.Then,using the sixth-order Wentzel-Kramers-Brillouin approximation,we examine QNMs of the BH disturbed by the three fields and derive quasinormal frequencies.The changes in QNM versus the core density parameter and the cloud string parameter for three disturbances are explored.We also investigate how the core density and the cloud string parameter affect the photon sphere and shadow radius.Interestingly,the study shows that the influence of Dehnen-type DM and cloud strings increases both the photon sphere and the shadow radius.Finally,we employ observational data from Sgr A^(*) and M87^(*) to set limitations on the BH parameters.
基金support from the Youth Innovation Promotion Association,Chinese Academy of Sciences(2020395)Strategic Priority Research Program of the Chinese Academy of Sciences grant XDB 41000000(Y.L.)+4 种基金National Natural Science Foundation of China(Nos.42273042 and 41931077)"From 0 to 1"Original Exploration Cultivation Project,Institute of Geochemistry,Chinese Academy of Sciences(DHSZZ2023-3)Guizhou Provincial Foundation for Excellent Scholars Program(No.GCC[2023]088)Guizhou Provincial Science and Technology Projects:QKHJCZK[2023]-General 473NSFC Young Scientist Fund(Nos.42303041 and 42403043)。
文摘Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,in particular reduction-oxidation processes that diff er from those in illuminated regions.To determine the characteristics of products formed during space weathering in PSRs,the lunar meteorite NWA 10203 with artifi cially added water was irradiated with a nanosecond laser to simulate a micro-meteorite bombardment of lunar soil containing water ice.The TEM results of the water-incorporated sample showed distinct amorphous rims that exhibited irregular thickness,poor stratifi cation,the appearance of bubbles,and a reduced number of npFe^(0).Additionally,EELS analysis showed the presence of ferric iron at the rim of the nanophase metallic iron particles(npFe^(0))in the amorphous rim with the involvement of water.The results suggest that water ice is another possible factor contributing to oxidation during micrometeorite bombardment on the lunar surface.In addition,it off ers a reference for a new space weathering model that incorporates water in PSRs,which could be widespread on asteroids with volatiles.
基金supported by the National Natural Science Foundation of China,Grant number U23B2089Shaanxi Provincial Natural Science Basic Research Program Project,Grant number 2024JC-YBQN-0554Scientific Research Program Funded by Shaanxi Provincial Education Department(Program No.24JK0597).
文摘During multi-cluster fracturing of horizontal wells,low-viscosity fracturing fluid permeates extensively along the fracture walls into the rock pores,exerting seepage forces on the rock skeleton.However,the mechanism of how seepage forces influence multi-cluster fracture propagation behavior remains unclear.In this study,we analyze the response relationship between the pore pressure field and the seepage field under transient seepage conditions.We established a numerical simulation model of multi-cluster fracture propagation in horizontal wells considering seepage forces based on the discrete element particle flow method.Using this model,we examined the mechanisms by which seepage forces affect the dynamic evolution of the induced stress field and fracture propagation behavior under various combinations of fracturing fluid viscosity,injection rate,in-situ stress,and cluster spacing.Numerical simulation results indicate that the infiltration of fracturing fluid into rock pores and the resulting seepage forces significantly alter the propagation patterns of inter-cluster fractures and the distribution of the induced stress field.Under the influence of seepage forces,hydraulic fractures suppressed by stress shadows are redirected and captured by adjacent fractures.Selecting appropriate fracturing fluid viscosity and injection rate can effectively utilize seepage forces to mitigate the inhibitory effects of the high compressive stress zones within stress shadows on intermediate fracture propagation,thereby increasing the likelihood of inter-fracture communication and the formation of a complex fracture network.This study not only underscores the importance of considering seepage forces in the design of multi-stage fracturing treatments but also provides critical theoretical insights for optimizing fracturing operation parameters.
文摘Goh Boon Teck is the chief artistic director of Toy Factory,a Singaporean theater company founded in 1990.According to Goh,a group of young people decided to organize their own theater company due to a love for drama.The“Toy”in the name of the theater company comes from a Thai shadow puppet artist who worked with them,and“Factory”highlights the organization’s devotion to training theater practitioners for the art community.Goh said that in addition to staging productions,Toy Factory has also vigorously worked to discover new drama artists including actors,designers,and playwrights.
基金the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Large Research Project under grant number RGP2/333/46。
文摘Verlinde's emergent gravity(VEG)posits that gravity arises as an emergent phenomenon rooted in the entropic properties of spacetime,challenging the traditional view of gravity as a fundamental force.Building on this paradigm,recent developments have introduced a novel class of black holes within the VEG framework,revealing intriguing connections between apparent dark matter effects and the distribution of baryonic matter.In this study,we delve into the observational signatures of a Simpson–Visser(SV)Minkowski core regular black hole in VEG,focusing on its shadow images and intensity profiles.Our analysis highlights the profound influence of model parameters,including A(governing baryonic matter distribution),B(strength of interaction between apparent dark matter and baryonic matter),and n(characterizing diverse spacetime geometries),on the effective potential and observable properties.Notably,we find that the modifications introduced by these parameters lead to distinct changes in the black hole's shadow size and intensity distribution.Comparing our results to the Reissner–Nordström(RN)black hole,we uncover a striking reduction in the apparent shadow size and an enhancement in intensity for the SV solution in VEG.
基金support of Dean Fund Project of the China National Institute of Standardization[Grant No.572025Y-12477]National Natural Science Foundation of China[Grant No.72204247].
文摘The marginal abatement cost(MAC)of CO_(2)emissions is one of the most critical indicators used to assess energy conservation and emission reduction.Although extensively measured,few studies have incorporated the influence of policy constraints when evaluating MAC.To address this gap,this paper proposes a nonparametric directional distance function approach under policy regulations to estimate the CO_(2)shadow price in the construction industry across 30 Chinese provinces from 2010 to 2017.Based on this enhanced method,four key findings emerge:①the annual CO_(2)shadow price exhibits an overall upward trend during the observation period;②regional shadow prices display marked variation across provinces;③regional heterogeneity in shadow prices has increased steadily over time;and④both urbanization rate and energy consumption per unit of gross domestic product are significantly negatively correlated with the CO_(2)shadow price.Finally,the paper offers several policy recommendations for CO_(2)emissions reduction in the Chinese construction industry at the national,industry,and enterprise levels.
基金funded by the Jiaying University Research Start-Up Fund(grant number 323E0431).
文摘Accurate fingertip detection is critical for translating hand gestures into actionable commands in vision-based human‒computer interaction(HCI)systems.However,challenges such as complex backgrounds,dynamic hand postures,and real-time processing constraints hinder reliable detection.This paper introduces a robust framework integrating three key innovations:(1)an adaptive Gaussian mixture model(GMM)enhanced with neighborhood pixel connectivity for precise motion extraction;(2)a weighted YCbCr color-space shadow removal algorithm to eliminate false positives;and(3)a centroid distance method refined with circularity constraints for accurate fingertip localization.Extensive experiments demonstrate a recognition accuracy of 97.26%across diverse scenarios,including varying illuminations,occlusions,and hand rotations.The algorithm processes each frame in 23.43 ms on average,satisfying real-time requirements.Comparative evaluations against state-of-the-art methods reveal significant improvements in precision(8.3%),recall(6.1%),and F-measure(7.8%).This work advances HCI applications such as virtual keyboards,gesture-controlled interfaces,and augmented reality systems.
基金supported by the National Natural Science Foundation of China under Grant No.11675143the National Key Research and Development Program of China under Grant No.2020YFC2201503。
文摘In this paper,we investigate the optical properties of a non-rotating charged black hole(BH)in the Einstein-Maxwell-scalar(EMS)theory,together with a plasma medium.We first consider the photon sphere and shadow radius under the impact of the plasma medium existing in the environment surrounding the BH in the EMS theory.We show that the radius of the photon sphere and the BH shadow decrease under the influence of the parameterβ.We further study gravitational weak lensing in detail by adapting general methods and derive the light ray's deflection angle around the BH together with the plasma environment.It is found that for uniform plasma,the deflection angle increases with the rise of the plasma parameter,whereas it decreases with the increase of the plasma parameter for non-uniform plasma.Besides,we also study the magnification of image brightness.
