Improving the transfer hydrogenation of N-heteroarenes is of key importance for various industrial pro-cesses and remains a challenge so far.We reported here a microcapsule-pyrolysis strategy to quasi-continuous synth...Improving the transfer hydrogenation of N-heteroarenes is of key importance for various industrial pro-cesses and remains a challenge so far.We reported here a microcapsule-pyrolysis strategy to quasi-continuous synthesis S,N co-doped carbon supported Co single atom catalysts(Co/SNC),which was used for transfer hydrogenation of quinoline with formic acid as the hydrogen donor.Given the unique ge-ometric and electronic properties of the Co single atoms,the excellent catalytic activity,selectivity and stability were observed.Benefiting from the quasi-continuous synthesis method,the as-obtained cata-lysts provide a reference for the large-scale preparation of single atom catalysts without amplification ef-fect.Highly catalytic performances and quasi-continuous preparation process,demonstrating a new and promising approach to rational design of atomically dispersed catalysts with maximum atomic efficiency in industrial.展开更多
High-power diode-pumped solid-state lasers(DPSSLs)can support many important applications owing to their simple setup and high efficiency.However,the thermal effect in the laser crystal is a major limiting factor for ...High-power diode-pumped solid-state lasers(DPSSLs)can support many important applications owing to their simple setup and high efficiency.However,the thermal effect in the laser crystal is a major limiting factor for laser power improvement.Here,we originally present a quasi-continuous-wave(QCW)diode-pumped monolithic Yb^(3+)-doped YCa_(4)O(BO_(3))_(3)(Yb:YCOB)laser and realize the power scaling at room temperature by removing the heat efficiently.The Yb:YCOB laser at 1024 nm is designed with a quantum efficiency of 95%.A high-power QCW laser is realized with an output peak power of up to 226.7 W,a pulse energy of 12.2 m J,and an optical-to-optical efficiency of 41.2%.To the best of our knowledge,this result represents the record peak power in Yb:YCOB lasers and should have promising applications in some modern devices requiring high-power and large-energy lasers.展开更多
Benefiting from the abrupt phase changes within subwavelength thicknesses,metasurfaces have been widely applied for lightweight and compact optical systems.Simultaneous broadband and high-efficiency characteristics ar...Benefiting from the abrupt phase changes within subwavelength thicknesses,metasurfaces have been widely applied for lightweight and compact optical systems.Simultaneous broadband and high-efficiency characteristics are highly attractive for the practical implementation of metasurfaces.However,current metasurface devices mostly adopt discrete micro/nano structures,which rarely realize both merits simultaneously.In this paper,dielectric metasurfaces composed of quasi-continuous nanostrips are proposed to overcome this limitation.Via quasi-continuous nanostrips metasurface,a normal focusing metalens and a superoscillatory lens overcoming the diffraction limit are designed and experimentally demonstrated.The quasi-continuous metadevices can operate in a broadband wavelength ranging from 450 nm to 1000nm and keep a high power efficiency.The average efficiency of the fabricated metalens reaches 54.24%,showing a significant improvement compared to the previously reported metalenses with the same thickness.The proposed methodology can be easily extended to design other metadevices with the advantages of broadband and high-efficiency in practical optical systems.展开更多
Research based on oil accumulation models is essential for exploring the hydrocarbon accumulation theory further.Studies on tight oil accumulation models focused on fan delta depositional systems,and in particular,sys...Research based on oil accumulation models is essential for exploring the hydrocarbon accumulation theory further.Studies on tight oil accumulation models focused on fan delta depositional systems,and in particular,systems involving source-reservoir separated type are scarce.To explore the accumulation model of tight oil in conglomerate,this study focused on the Permian-Triassic tight conglomerate oil in Mahu sag,Junggar Basin,using well drilling,well logging,seismic profiling,oil testing,and laboratory data,and analyzed the formation conditions,formation types,and distribution patterns of conglomerate reservoirs.The results show that,the conglomerate reservoirs are predominantly lithologic reservoirs and partly fault-lithologic reservoirs;there is no water evident at the edge or bottom around the reservoirs.The tight conglomerate layer in the delta plain subfacies of each fan exhibits high clay content and intense diagenesis,and the argillaceous rocks in the pro-fan delta subfacies and shallow lacustrine facies form the sealing and floor conditions.The sandy conglomerate of fan delta front subfacies is the main reservoir body.Additionally,strikeslip faulting in the Indosinian-Himalayan period formed an efficient faulting system for trans-stratal migration with Hercynian-Indosinian inverse faulting.Oil migration is driven by the overpressure caused by hydrocarbon generation from alkali lacustrine source rocks.The distribution of reservoirs is primarily controlled by the large fan bodies,namely the Zhongguai,Baijiantan,Karamay,Huangyangquan,Xiazijie,Xiayan,and Dabasong fans.Each fan body forms a group of reservoirs or oilfields,resulting in a widely distributed pattern,according to which reservoir and sealing constitute one whole body—i.e.,patterns of“one sand and one reservoir,one fan and one field.”This results in a quasi-continuous accumulation model,which includes strong oil charging,efficient faulting transportation,trans-stratal migration,and lithologic trapped accumulation.The proposed model is an important supplement to the existing model of quasi-continuous oil and gas accumulation.Overall,this study enriches unconventional oil and gas accumulation theories.展开更多
To address the low accuracy and stability when applying classical control theory in distribution networks with distributed generation,a control method involving flexible multistate switches(FMSs)is proposed in this st...To address the low accuracy and stability when applying classical control theory in distribution networks with distributed generation,a control method involving flexible multistate switches(FMSs)is proposed in this study.This approach is based on an improved double-loop recursive fuzzy neural network(DRFNN)sliding mode,which is intended to stably achieve multiterminal power interaction and adaptive arc suppression for single-phase ground faults.First,an improved DRFNN sliding mode control(SMC)method is proposed to overcome the chattering and transient overshoot inherent in the classical SMC and reduce the reliance on a precise mathematical model of the control system.To improve the robustness of the system,an adaptive parameter-adjustment strategy for the DRFNN is designed,where its dynamic mapping capabilities are leveraged to improve the transient compensation control.Additionally,a quasi-continuous second-order sliding mode controller with a calculus-driven sliding mode surface is developed to improve the current monitoring accuracy and enhance the system stability.The stability of the proposed method and the convergence of the network parameters are verified using the Lyapunov theorem.A simulation model of the three-port FMS with its control system is constructed in MATLAB/Simulink.The simulation result confirms the feasibility and effectiveness of the proposed control strategy based on a comparative analysis.展开更多
The lower Ordovician mid-assemblage Formations in the central Ordos Basin of China host prolific gas resources,and most hydrocarbon reserves are stored in naturally-fractured reservoirs.Thus,fracture pathway systems m...The lower Ordovician mid-assemblage Formations in the central Ordos Basin of China host prolific gas resources,and most hydrocarbon reserves are stored in naturally-fractured reservoirs.Thus,fracture pathway systems may have a significant impact on reservoir performance.This article focuses on the core-and laboratory-based characterization of fractures.Through the developmental degrees,extended scale,output state and filling characteristics of various types of fractures,the results show that there are three distinct fracture types:1)nearly vertical fractures,2)oblique fractures,and 3)horizontal fractures.Based on a systematic study of the characterization of reservoir space,the main geologic setting of natural gas accumulation and the regional tectonic background,type 1 is mainly driven by the tectonic formation mechanism,and type 3 and parts of low-angle fractures in type 2 are induced by the diagenetic formation mechanism.While recovered paleopressure for methane-rich aqueous inclusions trapped in fracture-filling cement indicates that the fracture opening and growth are consistent with gas maturation and charge and such high-angle fractures in type 2 are caused by the compound formation mechanism.The fractures to hydrocarbon accumulation may play a more significant role in improving the quality of reservoir porosity.Furthermore,connected fractures,dissolved pores and cavities together constitute the three-dimensional pore-cave-fracture network pathway systems,with faults serving as the dominant charge pathways of highly pressurized gas in the study area.Our results demonstrate that protracted growth of a pervasive fracture system is not only the consequence of various formation mechanisms but also intrinsic to quasi-continuous accumulation reservoirs.展开更多
Strong law of large numbers is a fundamental theory in probability and statistics. When the measure tool is nonadditive, this law is very different from additive case. In 2010 Chen investigated the strong law of large...Strong law of large numbers is a fundamental theory in probability and statistics. When the measure tool is nonadditive, this law is very different from additive case. In 2010 Chen investigated the strong law of large numbers under upper probabilityVby assumingVis continuous. This assumption is very strong. Upper probabilities may not be continuous. In this paper we prove the strong law of large numbers for an upper probability without the continuity assumption whereby random variables are quasi-continuous and the upper probability is generated by a weakly compact family of probabilities on a complete and separable metric sample space.展开更多
Based on the extensive studies of conventional and unconventional hydrocarbon accumulations,the concept,classification and formation as well as distribution of petroleum reservoirs are discussed.The revised concept de...Based on the extensive studies of conventional and unconventional hydrocarbon accumulations,the concept,classification and formation as well as distribution of petroleum reservoirs are discussed.The revised concept defined the petroleum reservoir as a continuous hydrocarbon accumulation in a single or a set of reservoirs with an independent or uniform pressure system.In terms of the pattern of hydrocarbon accumulation and distribution,the hydrocarbon accumulations are classified into three basic types,i.e.,the continuous accumulation,the quasi-continuous accumulation and the discontinuous accumulation.The hydrocarbon accumulation was demonstrated as a process from continuous accumulation to discontinuous accumulation,and therefore these three basic types of hydrocarbon accumulations were identified.The continuous hydrocarbon accumulation is principally formed in source rocks,and typical examples are shale hydrocarbon reservoirs and coal-bed methane reservoirs;it is mainly characterized by tight-ultra tight reservoirs with permeability of nanodarcy to millidarcy;the hydrocarbons occurred in free,adsorbed or dissolved state;a continuous accumulation comprises actually only a single reservoir,and hydrocarbons are extensively and continuously distributed within the scope of effective source rocks;the accumulation has neither defined boundaries nor bottom or edge water;oil and gas mainly accumulate in situ or near the generation of hydrocarbons with no prominent migration;this hydrocarbon accumulation process is basically not controlled by traps.The quasicontinuous hydrocarbon accumulation mostly occurs in the tight reservoirs adjacent to source rocks,and typical examples are most of tight hydrocarbon reservoirs;the hydrocarbons are distributed quasicontinuously in large areas,and each quasi-continuous hydrocarbon accumulation includes numerous adjacent small-to medium-size reservoirs;reservoirs of this kind of hydrocarbon accumulation have no defined boundaries,no or only local edge and bottom water distribution,and no regional oil-gas-water inversion;hydrocarbons are pervasively charged in large areas,and oil and gas accumulation is caused by primary migration and short-distance secondary migration;the hydrocarbon migration and accumulation is principally driven by non-buoyant forces in non-Darcy flow;and the hydrocarbon accumulation is basically not controlled by anticline traps,but largely by non-anticline traps,especially lithological traps.The discontinuous hydrocarbon accumulation is also named as the hydrocarbon accumulation of the conventional-trap type,and typically occurs in conventional reservoirs,but some tight hydrocarbon reservoirs,coalbed methane reservoirs and even possible shale hydrocarbon reservoirs also belong to this kind of hydrocarbon accumulation;the hydrocarbon reservoirs are distributed discontinuously,and have clear boundaries and complete edge water or bottom water;the hydrocarbon migration and accumulation is mainly driven by buoyancy and secondary migration is usually indispensable;the hydrocarbon accumulation is strictly controlled by various traps,especially structural traps.In a petroliferous basin,above three types of hydrocarbon accumulation may coexist,andhydrocarbons are often derived from a common source kitchen(s).Therefore,these three types of hydrocarbon accumulation should be considered and studied as a whole to maximize hydrocarbon exploration efficiencvy.展开更多
基金financial support from the National Natural Science Foundation of China(Nos.22078371,21938001,21961160741)Guangdong Provincial Key R&D Programme(No.2019B110206002)+4 种基金Special fund for Local Science and Technology Development by the Central Government,Local Innovative and Research Teams Project of Guangdong Pearl River Talents Pro-gram(No.2017BT01C102)the NSF of Guang-dong Province(No.2020A1515011141)the National key Research and Development Program Nanotechnology Specific Project(No.2020YFA0210900)the Science and Technology Key Project of Guangdong Province,China(No.2020B010188002)The Project Supported by Guangdong Natural Science Foundation(No.2021A1515010163).
文摘Improving the transfer hydrogenation of N-heteroarenes is of key importance for various industrial pro-cesses and remains a challenge so far.We reported here a microcapsule-pyrolysis strategy to quasi-continuous synthesis S,N co-doped carbon supported Co single atom catalysts(Co/SNC),which was used for transfer hydrogenation of quinoline with formic acid as the hydrogen donor.Given the unique ge-ometric and electronic properties of the Co single atoms,the excellent catalytic activity,selectivity and stability were observed.Benefiting from the quasi-continuous synthesis method,the as-obtained cata-lysts provide a reference for the large-scale preparation of single atom catalysts without amplification ef-fect.Highly catalytic performances and quasi-continuous preparation process,demonstrating a new and promising approach to rational design of atomically dispersed catalysts with maximum atomic efficiency in industrial.
基金supported by the National Key Research and Development Program of China(Nos.2021YFA0717800,2021YFB3601504,and 2023YFF0718801)the National Natural Science Foundation of China(Nos.52025021,52422201,52372010,and U23A20558)+1 种基金the Natural Science Foundation of Shandong Province(No.ZR2023ZD53)the Future Plans of Young Scholars at Shandong University。
文摘High-power diode-pumped solid-state lasers(DPSSLs)can support many important applications owing to their simple setup and high efficiency.However,the thermal effect in the laser crystal is a major limiting factor for laser power improvement.Here,we originally present a quasi-continuous-wave(QCW)diode-pumped monolithic Yb^(3+)-doped YCa_(4)O(BO_(3))_(3)(Yb:YCOB)laser and realize the power scaling at room temperature by removing the heat efficiently.The Yb:YCOB laser at 1024 nm is designed with a quantum efficiency of 95%.A high-power QCW laser is realized with an output peak power of up to 226.7 W,a pulse energy of 12.2 m J,and an optical-to-optical efficiency of 41.2%.To the best of our knowledge,this result represents the record peak power in Yb:YCOB lasers and should have promising applications in some modern devices requiring high-power and large-energy lasers.
基金the financial support by National Natural Science Foundation of China under contract No.61905031,61905073National Key R&D Program of China under contract No.2020YFC1522900Natural Science Foundation of Chongqing under contract No.CSTB2023NSCQMSX0992。
文摘Benefiting from the abrupt phase changes within subwavelength thicknesses,metasurfaces have been widely applied for lightweight and compact optical systems.Simultaneous broadband and high-efficiency characteristics are highly attractive for the practical implementation of metasurfaces.However,current metasurface devices mostly adopt discrete micro/nano structures,which rarely realize both merits simultaneously.In this paper,dielectric metasurfaces composed of quasi-continuous nanostrips are proposed to overcome this limitation.Via quasi-continuous nanostrips metasurface,a normal focusing metalens and a superoscillatory lens overcoming the diffraction limit are designed and experimentally demonstrated.The quasi-continuous metadevices can operate in a broadband wavelength ranging from 450 nm to 1000nm and keep a high power efficiency.The average efficiency of the fabricated metalens reaches 54.24%,showing a significant improvement compared to the previously reported metalenses with the same thickness.The proposed methodology can be easily extended to design other metadevices with the advantages of broadband and high-efficiency in practical optical systems.
基金the National Science and Technology Major Project of China for their support。
文摘Research based on oil accumulation models is essential for exploring the hydrocarbon accumulation theory further.Studies on tight oil accumulation models focused on fan delta depositional systems,and in particular,systems involving source-reservoir separated type are scarce.To explore the accumulation model of tight oil in conglomerate,this study focused on the Permian-Triassic tight conglomerate oil in Mahu sag,Junggar Basin,using well drilling,well logging,seismic profiling,oil testing,and laboratory data,and analyzed the formation conditions,formation types,and distribution patterns of conglomerate reservoirs.The results show that,the conglomerate reservoirs are predominantly lithologic reservoirs and partly fault-lithologic reservoirs;there is no water evident at the edge or bottom around the reservoirs.The tight conglomerate layer in the delta plain subfacies of each fan exhibits high clay content and intense diagenesis,and the argillaceous rocks in the pro-fan delta subfacies and shallow lacustrine facies form the sealing and floor conditions.The sandy conglomerate of fan delta front subfacies is the main reservoir body.Additionally,strikeslip faulting in the Indosinian-Himalayan period formed an efficient faulting system for trans-stratal migration with Hercynian-Indosinian inverse faulting.Oil migration is driven by the overpressure caused by hydrocarbon generation from alkali lacustrine source rocks.The distribution of reservoirs is primarily controlled by the large fan bodies,namely the Zhongguai,Baijiantan,Karamay,Huangyangquan,Xiazijie,Xiayan,and Dabasong fans.Each fan body forms a group of reservoirs or oilfields,resulting in a widely distributed pattern,according to which reservoir and sealing constitute one whole body—i.e.,patterns of“one sand and one reservoir,one fan and one field.”This results in a quasi-continuous accumulation model,which includes strong oil charging,efficient faulting transportation,trans-stratal migration,and lithologic trapped accumulation.The proposed model is an important supplement to the existing model of quasi-continuous oil and gas accumulation.Overall,this study enriches unconventional oil and gas accumulation theories.
基金the Natural Science Foundation of Fujian,China(No.2021J01633).
文摘To address the low accuracy and stability when applying classical control theory in distribution networks with distributed generation,a control method involving flexible multistate switches(FMSs)is proposed in this study.This approach is based on an improved double-loop recursive fuzzy neural network(DRFNN)sliding mode,which is intended to stably achieve multiterminal power interaction and adaptive arc suppression for single-phase ground faults.First,an improved DRFNN sliding mode control(SMC)method is proposed to overcome the chattering and transient overshoot inherent in the classical SMC and reduce the reliance on a precise mathematical model of the control system.To improve the robustness of the system,an adaptive parameter-adjustment strategy for the DRFNN is designed,where its dynamic mapping capabilities are leveraged to improve the transient compensation control.Additionally,a quasi-continuous second-order sliding mode controller with a calculus-driven sliding mode surface is developed to improve the current monitoring accuracy and enhance the system stability.The stability of the proposed method and the convergence of the network parameters are verified using the Lyapunov theorem.A simulation model of the three-port FMS with its control system is constructed in MATLAB/Simulink.The simulation result confirms the feasibility and effectiveness of the proposed control strategy based on a comparative analysis.
基金Project (2011ZX05007-004) supported by the National Sciences and Technologies,ChinaProject (41502132) supported by the National Natural Science Foundation of China
文摘The lower Ordovician mid-assemblage Formations in the central Ordos Basin of China host prolific gas resources,and most hydrocarbon reserves are stored in naturally-fractured reservoirs.Thus,fracture pathway systems may have a significant impact on reservoir performance.This article focuses on the core-and laboratory-based characterization of fractures.Through the developmental degrees,extended scale,output state and filling characteristics of various types of fractures,the results show that there are three distinct fracture types:1)nearly vertical fractures,2)oblique fractures,and 3)horizontal fractures.Based on a systematic study of the characterization of reservoir space,the main geologic setting of natural gas accumulation and the regional tectonic background,type 1 is mainly driven by the tectonic formation mechanism,and type 3 and parts of low-angle fractures in type 2 are induced by the diagenetic formation mechanism.While recovered paleopressure for methane-rich aqueous inclusions trapped in fracture-filling cement indicates that the fracture opening and growth are consistent with gas maturation and charge and such high-angle fractures in type 2 are caused by the compound formation mechanism.The fractures to hydrocarbon accumulation may play a more significant role in improving the quality of reservoir porosity.Furthermore,connected fractures,dissolved pores and cavities together constitute the three-dimensional pore-cave-fracture network pathway systems,with faults serving as the dominant charge pathways of highly pressurized gas in the study area.Our results demonstrate that protracted growth of a pervasive fracture system is not only the consequence of various formation mechanisms but also intrinsic to quasi-continuous accumulation reservoirs.
文摘Strong law of large numbers is a fundamental theory in probability and statistics. When the measure tool is nonadditive, this law is very different from additive case. In 2010 Chen investigated the strong law of large numbers under upper probabilityVby assumingVis continuous. This assumption is very strong. Upper probabilities may not be continuous. In this paper we prove the strong law of large numbers for an upper probability without the continuity assumption whereby random variables are quasi-continuous and the upper probability is generated by a weakly compact family of probabilities on a complete and separable metric sample space.
基金This work was supported by National Science and Technology Major Project of China(Grant No.2011ZX05007-004 and Grant No.2011ZX05018001-004)National Natural Science Foundation of China(Grant No.41402121 and Grant No.41502132)+1 种基金Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2013JM5007)Shaanxi Provincial Natural Science Foundation of China(Grant No.2013JQ503).
文摘Based on the extensive studies of conventional and unconventional hydrocarbon accumulations,the concept,classification and formation as well as distribution of petroleum reservoirs are discussed.The revised concept defined the petroleum reservoir as a continuous hydrocarbon accumulation in a single or a set of reservoirs with an independent or uniform pressure system.In terms of the pattern of hydrocarbon accumulation and distribution,the hydrocarbon accumulations are classified into three basic types,i.e.,the continuous accumulation,the quasi-continuous accumulation and the discontinuous accumulation.The hydrocarbon accumulation was demonstrated as a process from continuous accumulation to discontinuous accumulation,and therefore these three basic types of hydrocarbon accumulations were identified.The continuous hydrocarbon accumulation is principally formed in source rocks,and typical examples are shale hydrocarbon reservoirs and coal-bed methane reservoirs;it is mainly characterized by tight-ultra tight reservoirs with permeability of nanodarcy to millidarcy;the hydrocarbons occurred in free,adsorbed or dissolved state;a continuous accumulation comprises actually only a single reservoir,and hydrocarbons are extensively and continuously distributed within the scope of effective source rocks;the accumulation has neither defined boundaries nor bottom or edge water;oil and gas mainly accumulate in situ or near the generation of hydrocarbons with no prominent migration;this hydrocarbon accumulation process is basically not controlled by traps.The quasicontinuous hydrocarbon accumulation mostly occurs in the tight reservoirs adjacent to source rocks,and typical examples are most of tight hydrocarbon reservoirs;the hydrocarbons are distributed quasicontinuously in large areas,and each quasi-continuous hydrocarbon accumulation includes numerous adjacent small-to medium-size reservoirs;reservoirs of this kind of hydrocarbon accumulation have no defined boundaries,no or only local edge and bottom water distribution,and no regional oil-gas-water inversion;hydrocarbons are pervasively charged in large areas,and oil and gas accumulation is caused by primary migration and short-distance secondary migration;the hydrocarbon migration and accumulation is principally driven by non-buoyant forces in non-Darcy flow;and the hydrocarbon accumulation is basically not controlled by anticline traps,but largely by non-anticline traps,especially lithological traps.The discontinuous hydrocarbon accumulation is also named as the hydrocarbon accumulation of the conventional-trap type,and typically occurs in conventional reservoirs,but some tight hydrocarbon reservoirs,coalbed methane reservoirs and even possible shale hydrocarbon reservoirs also belong to this kind of hydrocarbon accumulation;the hydrocarbon reservoirs are distributed discontinuously,and have clear boundaries and complete edge water or bottom water;the hydrocarbon migration and accumulation is mainly driven by buoyancy and secondary migration is usually indispensable;the hydrocarbon accumulation is strictly controlled by various traps,especially structural traps.In a petroliferous basin,above three types of hydrocarbon accumulation may coexist,andhydrocarbons are often derived from a common source kitchen(s).Therefore,these three types of hydrocarbon accumulation should be considered and studied as a whole to maximize hydrocarbon exploration efficiencvy.
