This paper reports that when an intense extraordinary-polarized laser beam illuminates a photorefractive BaTiO3 crystal, the dynamic beam fanning light is formed to be a thermal-like light source with a long correlati...This paper reports that when an intense extraordinary-polarized laser beam illuminates a photorefractive BaTiO3 crystal, the dynamic beam fanning light is formed to be a thermal-like light source with a long correlation time and wide spectral bandwidth. The experimental results of the first- and second-order double-slit interference with such photorefractive fanning light source, cart be understood with the theoretical simulation in terms of Hanbury-Brown and Twiss effect.展开更多
The Asian Development Bank’s decision to grant loans to disputed territories between China and India complicates the two countries’ border disputes Not long ago, the Executive Board of the Asian Development Bank (AD...The Asian Development Bank’s decision to grant loans to disputed territories between China and India complicates the two countries’ border disputes Not long ago, the Executive Board of the Asian Development Bank (ADB) adopted the India Country Partnership Strategy (2009-12). The document is of special concern to展开更多
Fanboys abound,and for some reason this zeitgeisty term is often reserved for fans of Macs.Now,just why anyone would obsess over a computer is anyone’s guess.Professing a preference is understandable,but becoming a b...Fanboys abound,and for some reason this zeitgeisty term is often reserved for fans of Macs.Now,just why anyone would obsess over a computer is anyone’s guess.Professing a preference is understandable,but becoming a bona fide fan?Perhaps I’m just not geeky enough.And,of course,the Chinese have their own slang to展开更多
This paper presents a design method to implement an antenna array characterized by ultra-wide beam coverage,low profile,and low Sidelobe Level(SLL)for the application of Unmanned Aerial Vehicle(UAV)air-to-ground commu...This paper presents a design method to implement an antenna array characterized by ultra-wide beam coverage,low profile,and low Sidelobe Level(SLL)for the application of Unmanned Aerial Vehicle(UAV)air-to-ground communication.The array consists of ten broadside-radiating,ultrawide-beamwidth elements that are cascaded by a central-symmetry series-fed network with tapered currents following Dolph-Chebyshev distribution to provide low SLL.First,an innovative design of end-fire Huygens source antenna that is compatible with metal ground is presented.A low-profile,half-mode Microstrip Patch Antenna(MPA)is utilized to serve as the magnetic dipole and a monopole is utilized to serves as the electric dipole,constructing the compact,end-fire,grounded Huygens source antenna.Then,two opposite-oriented end-fire Huygens source antennas are seamlessly integrated into a single antenna element in the form of monopole-loaded MPA to accomplish the ultrawide,broadside-radiating beam.Particular consideration has been applied into the design of series-fed network as well as antenna element to compensate the adverse coupling effects between elements on the radiation performance.Experiment indicates an ultrawide Half-Power Beamwidth(HPBW)of 161°and a low SLL of-25 dB with a high gain of 12 d Bi under a single-layer configuration.The concurrent ultrawide beamwidth and low SLL make it particularly attractive for applications of UAV air-to-ground communication.展开更多
To improve the efficiency and accuracy of path planning for fan inspection tasks in thermal power plants,this paper proposes an intelligent inspection robot path planning scheme based on an improved A^(*)algorithm.The...To improve the efficiency and accuracy of path planning for fan inspection tasks in thermal power plants,this paper proposes an intelligent inspection robot path planning scheme based on an improved A^(*)algorithm.The inspection robot utilizes multiple sensors to monitor key parameters of the fans,such as vibration,noise,and bearing temperature,and upload the data to the monitoring center.The robot’s inspection path employs the improved A^(*)algorithm,incorporating obstacle penalty terms,path reconstruction,and smoothing optimization techniques,thereby achieving optimal path planning for the inspection robot in complex environments.Simulation results demonstrate that the improved A^(*)algorithm significantly outperforms the traditional A^(*)algorithm in terms of total path distance,smoothness,and detour rate,effectively improving the execution efficiency of inspection tasks.展开更多
Given two graphs G and H,the Ramsey number R(G,H)is the smallest positive integer N such that every 2-coloring of the edges of K_(N)contains either a red G or a blue H.Let K_(N-1)■K_(1,k)be the graph obtained from K_...Given two graphs G and H,the Ramsey number R(G,H)is the smallest positive integer N such that every 2-coloring of the edges of K_(N)contains either a red G or a blue H.Let K_(N-1)■K_(1,k)be the graph obtained from K_(N-1)by adding anew vertexνconnecting k vertices of K_(N-1).A graph G withχ(G)=k+1 is called edge-critical if G contains an edge e such thatχ(G-e)=k.A considerable amount of research has been conducted by previous scholars on Ramsey numbers ofgraphs.In this study,we show that for an edge-critical graph G with x(G)=k+1,when k≥2,1≥2,and n is sufficiently large,R(G,K_(1)+nK_(t))=knt+1 and r,(G,K_(1)+nK_(t))=(k-1)nt+1.展开更多
A Peking Opera mask shaped like a monkey peered out from Charassri Jiraphas’phone case.In a caféat U-Center in Beijing’s Wudaokou area,she recalled her favorite scene from Shaw Brothers’cinematic adaptation of...A Peking Opera mask shaped like a monkey peered out from Charassri Jiraphas’phone case.In a caféat U-Center in Beijing’s Wudaokou area,she recalled her favorite scene from Shaw Brothers’cinematic adaptation of Journey to the West.“When the Monkey King shrinks into an insect just to enter the belly of Princess Iron Fan,”she recounted,her eyes sparkling with reminiscent wonder,“he punches and kicks until Princess Iron Fan can’t take it anymore,gives in,and lends him her Iron Fan.”Later,the Monkey King uses the magical fan to conjure such strong wind that the Flaming Mountains subside,breaking yet another impasse impeding the four Buddhist scriptureseeking monks.展开更多
While feeding her ostriches,Wang Xue swiftly responds to fans'questions with a sense of humor through her popular live‑streaming channel.Since Wang,30,an expert in ostrich farming,started live broadcasting on a sh...While feeding her ostriches,Wang Xue swiftly responds to fans'questions with a sense of humor through her popular live‑streaming channel.Since Wang,30,an expert in ostrich farming,started live broadcasting on a short‑video platform with her husband Han Peng,their ostrich farming business has flourished,garnering nearly 3 million fans on the platform.“The highest viewership for one single live broadcast reached over 6 million,”said Wang,adding that riding an ostrich at high speed was an essential part of her broadcasts.Through her videos,Wang brought fans close to the ostriches,providing details of their habits,farming methods and economic value.展开更多
Football is a popular sport all over the world,and it also has a large number of fans in China.However,in many international competitions,the Chinese team often fails to achieve the expected results.This situation mak...Football is a popular sport all over the world,and it also has a large number of fans in China.However,in many international competitions,the Chinese team often fails to achieve the expected results.This situation makes its fans very disappointed.But we should also see that the Chinese football community is making efforts to improve the situation.展开更多
The tectonic evolution of Borneo and the affiliation between Southern and Northern Borneo remains unclear.The Rajang and Crocker Fan sediments,as one of the largest ancient submarine fans in Southeast Asia have witnes...The tectonic evolution of Borneo and the affiliation between Southern and Northern Borneo remains unclear.The Rajang and Crocker Fan sediments,as one of the largest ancient submarine fans in Southeast Asia have witnessed the tectonic evolution of Borneo since at least the late Mesozoic.In this study,we present laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS)U-Pb dating and Hf isotopic results of detrital zircons from the Trusmadi and Crocker formations within the Crocker Fan of Sabah,Northern Borneo.Our results,coupled with previous data,show that the Crocker Fan sediments in Sabah of Northern Borneo display similar age spectra to the Rajang Fan sediments in Sarawak of Central Borneo,with two major age clusters at 130-80 and 280-200 Ma.Further provenance analysis based on mineral shape with a prismatic characteristic and similar detrital zircon Hf isotopes of the two formations illustrates that the Jurassic-Cretaceous and partly Triassic detrital zircons of the Crocker and Rajang Fan sediments were derived from the erosion of contemporaneous magmatic rocks;part of Permian-Triassic ones could be the recycling of the Jurassic deposits in SW Borneo.The initial provenance of these Permian-Triassic detritus could be synchronous magmatic rocks in the Tin belt of the Malay Peninsula.Combining with previous data,we propose that the entire Borneo continent,including both Southern and Northern Borneo,developed a common Mesozoic continental magmatic arc.Moreover,we postulate that the Rajang and Crocker fans formed in a fore-arc extensional rift basin related to the retreat of the subducted Paleo-Pacific Plate beneath the Northern Borneo margin.展开更多
Damming is a major geomorphological event characterized by catastrophic consequences and profound impacts on fluvial landscape evolution.Extensive Quaternary detrital deposits(DD)have been discovered in the Daju Basin...Damming is a major geomorphological event characterized by catastrophic consequences and profound impacts on fluvial landscape evolution.Extensive Quaternary detrital deposits(DD)have been discovered in the Daju Basin.Some research suggests that these deposits are potentially associated with Great Flood events in the mainstream region.However,considering the multiplicity and complexity of the deposition,they may also result from catastrophic debris flows in local gullies.Consequently,we conducted a comprehensive investigation of detrital deposits and collected 64 provenance samples.The sediment provenance was analyzed by grain size distribution and elemental composition characterization.The results are as follows:(1)The detrital deposits in the basin are predominantly composed of sand and gravel,with some clay.(2)The results of the elemental ratios and multivariate statistical analysis confirmed the similarity in material composition between the detrital deposits in the basin and those from the Muduoluo Gully.(3)The discovery of palaeolandslides and lacustrine deposits in the study area indicates the existence of ancient dammed lakes and historical river damming events.The detrital deposits likely represent fan delta sediments formed by water-land interactions caused by damming events.Our study highlights new insights into discriminating the provenances of detrital deposits in localized regions,providing a new perspective for investigating geological hazards in the Jinsha River Basin.展开更多
Fan deltas are usually constructed through episodic flood event with debris flow transforming to hyper-concentrated flow during sediments proceeding. However, the role of topography in controlling the flow transformat...Fan deltas are usually constructed through episodic flood event with debris flow transforming to hyper-concentrated flow during sediments proceeding. However, the role of topography in controlling the flow transformation and sediments aggradation has been less studied. This constrain studies of sediment distribution and understanding of graded profile. For lake basin sequences, geomorphological control is much stronger than lake level rise and fall. Under extreme conditions, sediments can still prograde when the lake level rises. Therefore, describing the influence of geomorphology on the flow transformation and stacking pattern of the lobes can provide a deeper understanding of the controlling factors of the lake basin stratigraphy sequence. Xiligou lake (XLG) fan delta from Xisai Basin provides an optimal case for addressing this issue. Three lobes developed on the XLG fan delta with significant differences in their morphologies, architectures, lithofacies, sediment distributions and topographies. Through trenching, drone photography, and satellite data, we analyzed the structure of the sediments and the distribution of sedimentary facies. Based on the analysis of debris flow and hyper-concentrated flow deposits, two transformation models corresponding to different topographies were established. Sediment unloading is caused by a frictional reduction or a sudden momentum loss in the sediments flow's carrying capacity, allowing the debris flow transforms to hyper-concentrated flow and then to stream flow during the movement. The role of topography in controlling sediment flow transformation and sediment distribution is clarified through forces analysis of sediment grain. The topographic gradient of the linear slope is constant, so the direction of fluid movement is consistent with the topographic direction. Therefore, sediment flows move on linear slope without collision with the bed and there is no sudden loss of momentum. The gradual or sudden reduction in topographic gradient of concave slopes forces a constant or sudden change in the direction of fluid movement, which facilitates the unloading of sediments and the transformation of flow. The sudden change of topography forces unloading of viscous component, and the non-viscous component pass over to form hyper-concentrated flow, often accompanied by remobilized large gravels. The graded profile was an equilibrium between the dynamics and resistance of sediment transport. Changes in lake level affect the graded profile by changing the elevation of sediment transport, which is the total gravitational potential energy. The instantaneous graded profile and temporary graded profile are different scales of equilibrium corresponding to hydrodynamic equilibrium and depositional trend respectively. This study reveals the role of geomorphological dynamics in controlling sedimentary body progradation, thus providing a new perspective on the analysis of lake basin stratigraphy sequence.展开更多
Heating,Ventilation,andAir Conditioning(HVAC)systems are critical formaintaining thermal comfort in office environments which also crucial for occupant well-being and productivity.This study investigates the impact of...Heating,Ventilation,andAir Conditioning(HVAC)systems are critical formaintaining thermal comfort in office environments which also crucial for occupant well-being and productivity.This study investigates the impact of integrating ceiling fans with higher air conditioning setpoints on thermal comfort and energy efficiency in office environments.Field measurements and questionnaire surveys were conducted to evaluate thermal comfort and energysaving potential under varying conditions.Results show that increasing the AC setpoint from 25○C to 27○C,combined with ceiling fan operation,reduced power consumption by 10%,achieving significant energy savings.Survey data confirmed that 85%of participants reported consistent thermal sensations across all conditions,with ceiling fans effectively compensating for higher setpoints through enhanced air circulation.CFDsimulations revealed that mediumspeed ceiling fan operation produced the most uniformairflowdistribution,with an average air velocity of 0.45 m/s,and minimized temperature variations,ensuring balanced thermal conditions.Temperature analysis showed a reduction in hotspots and cold zones,maintaining an average temperature deviation of less than±0.5○C.Predicted Mean Vote(PMV)evaluations at a 27○C setpoint indicated improved thermal comfort,with average PMV values around−0.3,corresponding to a“neutral”thermal sensation.These findings demonstrate the effectiveness of integrating ceiling fans with HVAC systems in achieving energy efficiency and occupant comfort,offering a sustainable approach to reducing AC energy consumption in office environments.展开更多
As the environmental problems become increasingly serious,distributed electrical propulsion systems with higher aerodynamic efficiency and lower pollution emission have received extensive attention in recent years.The...As the environmental problems become increasingly serious,distributed electrical propulsion systems with higher aerodynamic efficiency and lower pollution emission have received extensive attention in recent years.The distributed electrical propulsion usually employs the new aero-propulsion integrated configuration.A simulation strategy for internal and external flow coupling based on the combination of lifting line theory and body force method is proposed.The lifting line theory and body force method as source term are embedded into the Navier-Stokes formulation.The lift and drag characteristics of the aero-propulsion coupling configuration are simulated.The results indicate that the coupling configuration has the most obvious lift augmentation at 12°angle of attack,which can provide an 11.11%increase in lift for the airfoil.At 0°angle of attack,the pressure difference on the lip parts provides the thrust component,which results in a lower drag coefficient.Additionally,the failure impact of a ducted fan at the middle or edge on aerodynamics is investigated.For the two failure conditions,the lift of the coupling configuration is decreased significantly by 27.85%and 26.14%respectively,and the lip thrust is decreased by 70.74%and 56.48%respectively.展开更多
1. Introduction Research on the ground effect of rotor can be traced back to the 1930s1.However, few studies have been conducted on the aerodynamic characteristics of rotors and ducted fans when hovering near a water ...1. Introduction Research on the ground effect of rotor can be traced back to the 1930s1.However, few studies have been conducted on the aerodynamic characteristics of rotors and ducted fans when hovering near a water surface for an extended period.With the emergence of cross-media rotorcraft, rotor wakes interact violently with the water surface to generate large-scale,air–water droplet mixed flows (hereafter referred to as mixed air–water flows). Rotors operating in mixed air–water flows always have aerodynamic performances that are different from those owing to the In-Ground Effect (IGE) and Out-of Ground Effect (OGE). Accordingly, this effect is called the Near-Water Effect (NWE) of the rotor2,and it usually causes thrust loss and torque increase.展开更多
1 With no famous coaches and only a small number of professional players,an amateur soccer league in Jiangsu Province has caught people's attention,mostly because of local fans'great passion and humorous talk.
The study on sand body connectivity and distribution patterns is of great significance for well emplacement and injection-production pattern analysis in the A oilfield of the Weixi?nan Sag currently at a pre-developme...The study on sand body connectivity and distribution patterns is of great significance for well emplacement and injection-production pattern analysis in the A oilfield of the Weixi?nan Sag currently at a pre-development stage.Based on the current drilling data,seismic data,and fault development characteristics,this study investigates the connectivity,geometric morphology,planar distribution,and vertical evolution of composite sand bodies(multi-stage superimposed channel sand bodies)within the fault block using seismic forward and inversion modeling.The El3I oil layer group in the third member of the Liushagang Formation is developed in the fan delta-front sub-facies,which mainly consists of subaqueous distributary channels.The thickness of single-stage subaqueous distributary channel sand bodies ranges from 2 to 6 m,and the width of composite channel sand bodies varies from 50 to 100 m.Under the long-term transgression background,the subaqueous distributary channels in the El3I oil layer group are relatively narrow,forming superimposed and continuous composite channel sand bodies through lateral migration and vertical stacking.The long-term base-level cycles control the width of subaqueous distributary channels,while the mid-term base-level cycles control the thickness of these channels.The subaqueous distributary channels developed during the late stage of mid-term base-level fall are thicker than those formed during the early stage.Accordingly,quantitative relationships between channel thickness and width are established for the early and late stages of mid-term base-level fall,to finely depict the evolution patterns of channel sand body geometry and stacking styles across different stages.These findings provide important guidance for accurately predicting the planar distribution and channel width of composite subaqueous distributary channels at different stages of the mid-term baselevel cycles.展开更多
基金Project supported by the National Fundamental Research Program of China （Project No 2001CB309310）, and the National Natural Science Foundation of China （Project No 10574015）.Acknowledgment 0ne of the authors, Wang Kaige, acknowledges the financial support of the Abdus Salam International Centre for Theoretical Physics （ICTP） under the Associate Programme.
文摘This paper reports that when an intense extraordinary-polarized laser beam illuminates a photorefractive BaTiO3 crystal, the dynamic beam fanning light is formed to be a thermal-like light source with a long correlation time and wide spectral bandwidth. The experimental results of the first- and second-order double-slit interference with such photorefractive fanning light source, cart be understood with the theoretical simulation in terms of Hanbury-Brown and Twiss effect.
文摘The Asian Development Bank’s decision to grant loans to disputed territories between China and India complicates the two countries’ border disputes Not long ago, the Executive Board of the Asian Development Bank (ADB) adopted the India Country Partnership Strategy (2009-12). The document is of special concern to
文摘Fanboys abound,and for some reason this zeitgeisty term is often reserved for fans of Macs.Now,just why anyone would obsess over a computer is anyone’s guess.Professing a preference is understandable,but becoming a bona fide fan?Perhaps I’m just not geeky enough.And,of course,the Chinese have their own slang to
基金supported by the National Natural Science Foundation of China(No.62371080 and 62031006)the National Science Foundation of Chongqing,China(No.CSTB2022NSCQ-MSX0597)the Venture&Innovation Support Program for Chongqing Overseas Returnees,China(No.cx2022063)。
文摘This paper presents a design method to implement an antenna array characterized by ultra-wide beam coverage,low profile,and low Sidelobe Level(SLL)for the application of Unmanned Aerial Vehicle(UAV)air-to-ground communication.The array consists of ten broadside-radiating,ultrawide-beamwidth elements that are cascaded by a central-symmetry series-fed network with tapered currents following Dolph-Chebyshev distribution to provide low SLL.First,an innovative design of end-fire Huygens source antenna that is compatible with metal ground is presented.A low-profile,half-mode Microstrip Patch Antenna(MPA)is utilized to serve as the magnetic dipole and a monopole is utilized to serves as the electric dipole,constructing the compact,end-fire,grounded Huygens source antenna.Then,two opposite-oriented end-fire Huygens source antennas are seamlessly integrated into a single antenna element in the form of monopole-loaded MPA to accomplish the ultrawide,broadside-radiating beam.Particular consideration has been applied into the design of series-fed network as well as antenna element to compensate the adverse coupling effects between elements on the radiation performance.Experiment indicates an ultrawide Half-Power Beamwidth(HPBW)of 161°and a low SLL of-25 dB with a high gain of 12 d Bi under a single-layer configuration.The concurrent ultrawide beamwidth and low SLL make it particularly attractive for applications of UAV air-to-ground communication.
文摘To improve the efficiency and accuracy of path planning for fan inspection tasks in thermal power plants,this paper proposes an intelligent inspection robot path planning scheme based on an improved A^(*)algorithm.The inspection robot utilizes multiple sensors to monitor key parameters of the fans,such as vibration,noise,and bearing temperature,and upload the data to the monitoring center.The robot’s inspection path employs the improved A^(*)algorithm,incorporating obstacle penalty terms,path reconstruction,and smoothing optimization techniques,thereby achieving optimal path planning for the inspection robot in complex environments.Simulation results demonstrate that the improved A^(*)algorithm significantly outperforms the traditional A^(*)algorithm in terms of total path distance,smoothness,and detour rate,effectively improving the execution efficiency of inspection tasks.
基金supported by the National Key Research and Development Program of China(2023YFA1010200,2020YFA0713100)the National Natural Science Foundation of China(12071453)the Innovation Program for Quantum Science and Technology(2021ZD0302902).
文摘Given two graphs G and H,the Ramsey number R(G,H)is the smallest positive integer N such that every 2-coloring of the edges of K_(N)contains either a red G or a blue H.Let K_(N-1)■K_(1,k)be the graph obtained from K_(N-1)by adding anew vertexνconnecting k vertices of K_(N-1).A graph G withχ(G)=k+1 is called edge-critical if G contains an edge e such thatχ(G-e)=k.A considerable amount of research has been conducted by previous scholars on Ramsey numbers ofgraphs.In this study,we show that for an edge-critical graph G with x(G)=k+1,when k≥2,1≥2,and n is sufficiently large,R(G,K_(1)+nK_(t))=knt+1 and r,(G,K_(1)+nK_(t))=(k-1)nt+1.
文摘A Peking Opera mask shaped like a monkey peered out from Charassri Jiraphas’phone case.In a caféat U-Center in Beijing’s Wudaokou area,she recalled her favorite scene from Shaw Brothers’cinematic adaptation of Journey to the West.“When the Monkey King shrinks into an insect just to enter the belly of Princess Iron Fan,”she recounted,her eyes sparkling with reminiscent wonder,“he punches and kicks until Princess Iron Fan can’t take it anymore,gives in,and lends him her Iron Fan.”Later,the Monkey King uses the magical fan to conjure such strong wind that the Flaming Mountains subside,breaking yet another impasse impeding the four Buddhist scriptureseeking monks.
文摘While feeding her ostriches,Wang Xue swiftly responds to fans'questions with a sense of humor through her popular live‑streaming channel.Since Wang,30,an expert in ostrich farming,started live broadcasting on a short‑video platform with her husband Han Peng,their ostrich farming business has flourished,garnering nearly 3 million fans on the platform.“The highest viewership for one single live broadcast reached over 6 million,”said Wang,adding that riding an ostrich at high speed was an essential part of her broadcasts.Through her videos,Wang brought fans close to the ostriches,providing details of their habits,farming methods and economic value.
文摘Football is a popular sport all over the world,and it also has a large number of fans in China.However,in many international competitions,the Chinese team often fails to achieve the expected results.This situation makes its fans very disappointed.But we should also see that the Chinese football community is making efforts to improve the situation.
基金jointly supported by the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources,Xiamen(No.2018002)the Guangxi Natural Science Fundation(No.2022GXNSFBA035588)+1 种基金the National Natural Science Foundation of China(Nos.41506050,41402193)the Scientific Research Foundation of Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration(No.19-185-17-09)。
文摘The tectonic evolution of Borneo and the affiliation between Southern and Northern Borneo remains unclear.The Rajang and Crocker Fan sediments,as one of the largest ancient submarine fans in Southeast Asia have witnessed the tectonic evolution of Borneo since at least the late Mesozoic.In this study,we present laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS)U-Pb dating and Hf isotopic results of detrital zircons from the Trusmadi and Crocker formations within the Crocker Fan of Sabah,Northern Borneo.Our results,coupled with previous data,show that the Crocker Fan sediments in Sabah of Northern Borneo display similar age spectra to the Rajang Fan sediments in Sarawak of Central Borneo,with two major age clusters at 130-80 and 280-200 Ma.Further provenance analysis based on mineral shape with a prismatic characteristic and similar detrital zircon Hf isotopes of the two formations illustrates that the Jurassic-Cretaceous and partly Triassic detrital zircons of the Crocker and Rajang Fan sediments were derived from the erosion of contemporaneous magmatic rocks;part of Permian-Triassic ones could be the recycling of the Jurassic deposits in SW Borneo.The initial provenance of these Permian-Triassic detritus could be synchronous magmatic rocks in the Tin belt of the Malay Peninsula.Combining with previous data,we propose that the entire Borneo continent,including both Southern and Northern Borneo,developed a common Mesozoic continental magmatic arc.Moreover,we postulate that the Rajang and Crocker fans formed in a fore-arc extensional rift basin related to the retreat of the subducted Paleo-Pacific Plate beneath the Northern Borneo margin.
基金The National Key R&D Program of China,No.2023YFC3008300The Second Tibetan Plateau Scientific Expedition and Research(STEP),No.2019QZKK0903+1 种基金The Science and Technology Research Program of Institute of Mountain Hazards and Environment,CAS,No.IMHE-ZDRW-03National Natural Science Foundation of China,No.42071017。
文摘Damming is a major geomorphological event characterized by catastrophic consequences and profound impacts on fluvial landscape evolution.Extensive Quaternary detrital deposits(DD)have been discovered in the Daju Basin.Some research suggests that these deposits are potentially associated with Great Flood events in the mainstream region.However,considering the multiplicity and complexity of the deposition,they may also result from catastrophic debris flows in local gullies.Consequently,we conducted a comprehensive investigation of detrital deposits and collected 64 provenance samples.The sediment provenance was analyzed by grain size distribution and elemental composition characterization.The results are as follows:(1)The detrital deposits in the basin are predominantly composed of sand and gravel,with some clay.(2)The results of the elemental ratios and multivariate statistical analysis confirmed the similarity in material composition between the detrital deposits in the basin and those from the Muduoluo Gully.(3)The discovery of palaeolandslides and lacustrine deposits in the study area indicates the existence of ancient dammed lakes and historical river damming events.The detrital deposits likely represent fan delta sediments formed by water-land interactions caused by damming events.Our study highlights new insights into discriminating the provenances of detrital deposits in localized regions,providing a new perspective for investigating geological hazards in the Jinsha River Basin.
基金the Natural Science Foundation of China(42272124)the National Key R&D Program of China(2023YFF0804302)Quantitative anatomy of shallow fan deltas in western China project directed by Research Institute of Petroleum Exploration and Development(2020D-5008-03).
文摘Fan deltas are usually constructed through episodic flood event with debris flow transforming to hyper-concentrated flow during sediments proceeding. However, the role of topography in controlling the flow transformation and sediments aggradation has been less studied. This constrain studies of sediment distribution and understanding of graded profile. For lake basin sequences, geomorphological control is much stronger than lake level rise and fall. Under extreme conditions, sediments can still prograde when the lake level rises. Therefore, describing the influence of geomorphology on the flow transformation and stacking pattern of the lobes can provide a deeper understanding of the controlling factors of the lake basin stratigraphy sequence. Xiligou lake (XLG) fan delta from Xisai Basin provides an optimal case for addressing this issue. Three lobes developed on the XLG fan delta with significant differences in their morphologies, architectures, lithofacies, sediment distributions and topographies. Through trenching, drone photography, and satellite data, we analyzed the structure of the sediments and the distribution of sedimentary facies. Based on the analysis of debris flow and hyper-concentrated flow deposits, two transformation models corresponding to different topographies were established. Sediment unloading is caused by a frictional reduction or a sudden momentum loss in the sediments flow's carrying capacity, allowing the debris flow transforms to hyper-concentrated flow and then to stream flow during the movement. The role of topography in controlling sediment flow transformation and sediment distribution is clarified through forces analysis of sediment grain. The topographic gradient of the linear slope is constant, so the direction of fluid movement is consistent with the topographic direction. Therefore, sediment flows move on linear slope without collision with the bed and there is no sudden loss of momentum. The gradual or sudden reduction in topographic gradient of concave slopes forces a constant or sudden change in the direction of fluid movement, which facilitates the unloading of sediments and the transformation of flow. The sudden change of topography forces unloading of viscous component, and the non-viscous component pass over to form hyper-concentrated flow, often accompanied by remobilized large gravels. The graded profile was an equilibrium between the dynamics and resistance of sediment transport. Changes in lake level affect the graded profile by changing the elevation of sediment transport, which is the total gravitational potential energy. The instantaneous graded profile and temporary graded profile are different scales of equilibrium corresponding to hydrodynamic equilibrium and depositional trend respectively. This study reveals the role of geomorphological dynamics in controlling sedimentary body progradation, thus providing a new perspective on the analysis of lake basin stratigraphy sequence.
基金support by the National Science and Technology Council under Grant No.NSTC 112-2221-E-167-017-MY3.
文摘Heating,Ventilation,andAir Conditioning(HVAC)systems are critical formaintaining thermal comfort in office environments which also crucial for occupant well-being and productivity.This study investigates the impact of integrating ceiling fans with higher air conditioning setpoints on thermal comfort and energy efficiency in office environments.Field measurements and questionnaire surveys were conducted to evaluate thermal comfort and energysaving potential under varying conditions.Results show that increasing the AC setpoint from 25○C to 27○C,combined with ceiling fan operation,reduced power consumption by 10%,achieving significant energy savings.Survey data confirmed that 85%of participants reported consistent thermal sensations across all conditions,with ceiling fans effectively compensating for higher setpoints through enhanced air circulation.CFDsimulations revealed that mediumspeed ceiling fan operation produced the most uniformairflowdistribution,with an average air velocity of 0.45 m/s,and minimized temperature variations,ensuring balanced thermal conditions.Temperature analysis showed a reduction in hotspots and cold zones,maintaining an average temperature deviation of less than±0.5○C.Predicted Mean Vote(PMV)evaluations at a 27○C setpoint indicated improved thermal comfort,with average PMV values around−0.3,corresponding to a“neutral”thermal sensation.These findings demonstrate the effectiveness of integrating ceiling fans with HVAC systems in achieving energy efficiency and occupant comfort,offering a sustainable approach to reducing AC energy consumption in office environments.
基金the funding support from the Taihang Laboratory,China(No.D2024-1-0201).
文摘As the environmental problems become increasingly serious,distributed electrical propulsion systems with higher aerodynamic efficiency and lower pollution emission have received extensive attention in recent years.The distributed electrical propulsion usually employs the new aero-propulsion integrated configuration.A simulation strategy for internal and external flow coupling based on the combination of lifting line theory and body force method is proposed.The lifting line theory and body force method as source term are embedded into the Navier-Stokes formulation.The lift and drag characteristics of the aero-propulsion coupling configuration are simulated.The results indicate that the coupling configuration has the most obvious lift augmentation at 12°angle of attack,which can provide an 11.11%increase in lift for the airfoil.At 0°angle of attack,the pressure difference on the lip parts provides the thrust component,which results in a lower drag coefficient.Additionally,the failure impact of a ducted fan at the middle or edge on aerodynamics is investigated.For the two failure conditions,the lift of the coupling configuration is decreased significantly by 27.85%and 26.14%respectively,and the lip thrust is decreased by 70.74%and 56.48%respectively.
文摘1. Introduction Research on the ground effect of rotor can be traced back to the 1930s1.However, few studies have been conducted on the aerodynamic characteristics of rotors and ducted fans when hovering near a water surface for an extended period.With the emergence of cross-media rotorcraft, rotor wakes interact violently with the water surface to generate large-scale,air–water droplet mixed flows (hereafter referred to as mixed air–water flows). Rotors operating in mixed air–water flows always have aerodynamic performances that are different from those owing to the In-Ground Effect (IGE) and Out-of Ground Effect (OGE). Accordingly, this effect is called the Near-Water Effect (NWE) of the rotor2,and it usually causes thrust loss and torque increase.
文摘1 With no famous coaches and only a small number of professional players,an amateur soccer league in Jiangsu Province has caught people's attention,mostly because of local fans'great passion and humorous talk.
文摘The study on sand body connectivity and distribution patterns is of great significance for well emplacement and injection-production pattern analysis in the A oilfield of the Weixi?nan Sag currently at a pre-development stage.Based on the current drilling data,seismic data,and fault development characteristics,this study investigates the connectivity,geometric morphology,planar distribution,and vertical evolution of composite sand bodies(multi-stage superimposed channel sand bodies)within the fault block using seismic forward and inversion modeling.The El3I oil layer group in the third member of the Liushagang Formation is developed in the fan delta-front sub-facies,which mainly consists of subaqueous distributary channels.The thickness of single-stage subaqueous distributary channel sand bodies ranges from 2 to 6 m,and the width of composite channel sand bodies varies from 50 to 100 m.Under the long-term transgression background,the subaqueous distributary channels in the El3I oil layer group are relatively narrow,forming superimposed and continuous composite channel sand bodies through lateral migration and vertical stacking.The long-term base-level cycles control the width of subaqueous distributary channels,while the mid-term base-level cycles control the thickness of these channels.The subaqueous distributary channels developed during the late stage of mid-term base-level fall are thicker than those formed during the early stage.Accordingly,quantitative relationships between channel thickness and width are established for the early and late stages of mid-term base-level fall,to finely depict the evolution patterns of channel sand body geometry and stacking styles across different stages.These findings provide important guidance for accurately predicting the planar distribution and channel width of composite subaqueous distributary channels at different stages of the mid-term baselevel cycles.
