Here we report a novel generation/collection operation mode of scanning electrochemical microscopy,in which a theta micropipette was employed to support two adjacent water/1,2-dichloroethane interfaces separated by th...Here we report a novel generation/collection operation mode of scanning electrochemical microscopy,in which a theta micropipette was employed to support two adjacent water/1,2-dichloroethane interfaces separated by the thin central glass wall：one acts as the generator while the other as the collector.The generation current,collection current and collection efficiency were enhanced significantly when the tip approached to an insulate substrate.展开更多
VLF （very low frequency） mode instability with parallel AC electric field was studied for generalized loss-cone distribution with an index j, which is reducible to bi-Maxwellian, loss- cone and delta function for j ...VLF （very low frequency） mode instability with parallel AC electric field was studied for generalized loss-cone distribution with an index j, which is reducible to bi-Maxwellian, loss- cone and delta function for j = 0, 1 and co. The particle trajectories and dispersion relation are obtained through a kinetic approach and method of characteristic solutions. The calculations are compared with the observations of low frequency waves of Voyager 2. The growth rate of plasma parameters suited to magnetosphere of Uranus is obtained. It is inferred that the magnitude as well as frequency of AC （alternating current） field increases the growth rate and widen the band width significantly. In addition to temperature anisotropy, particles in plasma having generalized loss-cone distribution provide an additional source of energy.展开更多
The provision mode of the telecommunication service has experienced an evolving process, and showing the developing trend from distributed to centralized, from integrated to separated, and from closed to open. To suit...The provision mode of the telecommunication service has experienced an evolving process, and showing the developing trend from distributed to centralized, from integrated to separated, and from closed to open. To suit this trend, there will be three provision modes as Session Initiation Protocol (SIP) server, Open Service Access (OSA) application server and intelligent network(IN) in Next Generation Network (NGN), provides all kinds of services and applications to the subscribers. With the popularity of broadband access and Internet, the NGN will provide single telecommunication service and act as the important national infrastructure to offer various information services to the subscribers. The service provision mode will be more open, diversified, and individualized.展开更多
With the increasing exploration and development of typical hydrocarbon-rich depressions,such as the Dongpu Depression,the exploitation difficulty of shallow formations is increasing.There is an urgent need to clarify ...With the increasing exploration and development of typical hydrocarbon-rich depressions,such as the Dongpu Depression,the exploitation difficulty of shallow formations is increasing.There is an urgent need to clarify the hydrocarbon generation mode and hydrocarbon generation histories in deep formations.In this study,a gold tube-autoclave closed system was used to simulate the hydrocarbon generation processes and establish the hydrocarbon generation mode of different types of kerogen.Then,constrained by the thermal history and hydrocarbon generation kinetics,hydrocarbon generation histories were modeled.The results show that hydrocarbon generation evolution can be divided into five stages,and the maturity of each stage is different.The hydrocarbon generation history of the source rocks of the Shahejie 3 Formation mainly dates from the early depositional period of the Shahejie 1 Formation to the middle depositional period of the Dongying Formation.Hydrocarbon generation history constrained by thermal history and hydrocarbon generation kinetics is more in line with actual geological conditions.Moreover,this research can provide important hydrocarbon generation parameters for deep oil and gas exploration and exploitation of the Shahejie 3 Formation in the Dongpu Depression.展开更多
Evolutionary algorithms have been extensively utilized in practical applications.However,manually designed population updating formulas are inherently prone to the subjective influence of the designer.Genetic programm...Evolutionary algorithms have been extensively utilized in practical applications.However,manually designed population updating formulas are inherently prone to the subjective influence of the designer.Genetic programming(GP),characterized by its tree-based solution structure,is a widely adopted technique for optimizing the structure of mathematical models tailored to real-world problems.This paper introduces a GP-based framework(GPEAs)for the autonomous generation of update formulas,aiming to reduce human intervention.Partial modifications to tree-based GP have been instigated,encompassing adjustments to its initialization process and fundamental update operations such as crossover and mutation within the algorithm.By designing suitable function sets and terminal sets tailored to the selected evolutionary algorithm,and ultimately derive an improved update formula.The Cat Swarm Optimization Algorithm(CSO)is chosen as a case study,and the GP-EAs is employed to regenerate the speed update formulas of the CSO.To validate the feasibility of the GP-EAs,the comprehensive performance of the enhanced algorithm(GP-CSO)was evaluated on the CEC2017 benchmark suite.Furthermore,GP-CSO is applied to deduce suitable embedding factors,thereby improving the robustness of the digital watermarking process.The experimental results indicate that the update formulas generated through training with GP-EAs possess excellent performance scalability and practical application proficiency.展开更多
In connection with the current prospect of decarbonization of coal energy through the use of small nuclear power plants (SNPPs) at existing TPPs as heat sources for heat supply to municipal heating networks, there is ...In connection with the current prospect of decarbonization of coal energy through the use of small nuclear power plants (SNPPs) at existing TPPs as heat sources for heat supply to municipal heating networks, there is a technological need to improve heat supply schemes to increase their environmental friendliness and efficiency. The paper proves the feasibility of using the heat-feeding mode of ASHPs for urban heat supply by heating the network water with steam taken from the turbine. The ratio of electric and thermal power of a “nuclear” combined heat and power plant is given. The advantage of using a heat pump, which provides twice as much electrical power with the same heat output, is established. Taking into account that heat in these modes is supplied with different potential, the energy efficiency was used to compare these options. To increase the heat supply capacity, a scheme with the use of a high-pressure heater in the backpressure mode and with the heating of network water with hot steam was proposed. Heat supply from ASHPs is efficient and environmentally friendly even in the case of significant remoteness of heat consumers.展开更多
We propose that the brittle-ductile transition （BDT） controls the seismic cycle. In particular, the movements detected by space geodesy record the steady state deformation in the ductile lower crust, whereas the sti...We propose that the brittle-ductile transition （BDT） controls the seismic cycle. In particular, the movements detected by space geodesy record the steady state deformation in the ductile lower crust, whereas the stick-slip behavior of the brittle upper crust is constrained by its larger friction. GPS data allow analyzing the strain rate along active plate boundaries. In all tectonic settings, we propose that earthquakes primarily occur along active fault segments characterized by relative minima of strain rate, segments which are locked or slowly creeping. We discuss regional examples where large earthquakes happened in areas of relative low strain rate. Regardless the tectonic style, the interseismic stress and strain pattern inverts during the coseismic stage. Where a dilated band formed during the interseismic stage, this will be shortened at the coseismic stage, and vice-versa what was previously shortened, it will be dilated. The interseismic energy accumulation and the coseismic expenditure rather depend on the tectonic setting （extensional, contractional, or strike-slip）. The gravitational potential energy dominates along normal faults, whereas the elastic energy prevails for thrust earthquakes and performs work against the gravity force. The energy budget in strike-slip tectonic setting is also primarily due elastic energy. Therefore, precursors may be different as a function of the tectonic setting. In this model, with a given displacement, the magnitude of an earthquake results from the coseismic slip of the deformed volume above the BDT rather than only on the fault length, and it also depends on the fault kinematics.展开更多
In a grid-integrated photovoltaic system(GIPVS),there exist issues such as surplus active power and inadequate performance of maximum power point tracking(MPPT).A surplus active power causes the overvoltage problem at...In a grid-integrated photovoltaic system(GIPVS),there exist issues such as surplus active power and inadequate performance of maximum power point tracking(MPPT).A surplus active power causes the overvoltage problem at the point of common coupling in low-or medium-voltage grid during the peak hours of power generation.Additionally,the inadequate performance of the MPPT algorithm results in power loss due to high settling time during the sudden change of irradiance.Therefore,to solve the surplus power problem,the curtailment of active power is suggested with improved MPPT algorithm under variable irradiance conditions.In this paper,a derated power generation mode(DPGM)control strategy is presented for the curtailment of active power.Additionally,a drift-free(named as modified)perturb and observe(P&O)technique is also proposed to improve the performance of the MPPT algorithm.Consequently,the DPGM control scheme with the intermediate boost converter shaves the surplus active power during the peak hours of power generation.Furthermore,the modified MPPT algorithm deals with the fluctuation of irradiance during non-peak hours.Thus,the proposed control scheme delivers in a more efficient system during the peak hours of power generation.In addition,it reduces the power loss and settling time during the change of irradiance for non-peak hours.Based on the proposed control scheme,a 30 kW system has been simulated in MATLAB/Simulink using Simpower tools under different environmental conditions.展开更多
A laser-diode end-pumped Nd：YVO4 crystal laser is demonstrated to emit the first-order Laguerre- Gaussian （LGm） mode with 502-mW laser power and 22% slope efficiency. Tile LGm-mode is lased only when the pumping ar...A laser-diode end-pumped Nd：YVO4 crystal laser is demonstrated to emit the first-order Laguerre- Gaussian （LGm） mode with 502-mW laser power and 22% slope efficiency. Tile LGm-mode is lased only when the pumping area locates in the central part of the laser crystal＇s front surface, and thereafter the symmetrical LGm-HGol-TEM00 mode transition happens when laser crystal is moved laterally inside several-tens-micron area. The possible mechanism responsible for the phenomenon of symmetrical mode transition is also discussed.展开更多
Transverse mode characteristics of a laser are related to a variety of interesting applications. An on-demand mode solid laser in the 1064 nm band was proposed previously. In this paper, we provide a fiber laser for o...Transverse mode characteristics of a laser are related to a variety of interesting applications. An on-demand mode solid laser in the 1064 nm band was proposed previously. In this paper, we provide a fiber laser for on-demand modes in the 1550 nm band to prescribe the pure and high-quality emission of a higher-order transverse laser mode, based on a simple construction with one spatial light modulator(SLM) and a single-mode erbium-doped fiber(SM-EDF). The SLM is designated to generate the desired higher-order mode and separate the higher-order mode and the fundamental mode. The fundamental mode oscillates in the fiber ring laser, and therefore the SM-EDF can be pumped with a single-mode 980 nm laser, no matter what higher-order mode is prescribed.In this proof-of-principle experiment, high-quality higher-order modes are observed from LP01 to LP105.Stable emission and real-time switching between modes can be easily realized by altering the phase on the SLM. In addition, the propagation of the LP_(01), LP_(11), LP_(21), and LP_(02) modes from the fiber laser is also demonstrated in a four-mode few-mode fiber.展开更多
A technique for analyzing the nonlinear generation of the cumulative second har-monics of generalized Lamb modes in a layered planar structure is developed. A theoretical model for nonlinear generalized Lamb mode prop...A technique for analyzing the nonlinear generation of the cumulative second har-monics of generalized Lamb modes in a layered planar structure is developed. A theoretical model for nonlinear generalized Lamb mode propagation in a layered planar structure has been established, based on a partial plane wave approach. The nonlinearity is treated as a second-order perturbation of the linear elastic response. This model reveals some interesting features of the physics of the cumulative second harmonic generation. Although Lamb mode propagation is dispersive in a layered structure, the results of this analysis show that the amplitudes of the second harmonics do accumulate with propagation distance under certain special conditions. On the basis of the boundary and initial conditions of excitation, the formal solution of the cumulative second harmonic has been derived. Using the formal solution, we have performed some numerical simulations and obtained the cumulative second harmonic field patterns, illus-trating the distortion effect along the propagation distance, as well as the dependence of the field patterns on the position of the excitation source.展开更多
The increasing amount of data exchange requires higher-capacity optical communication links.Mode division multiplexing(MDM)is considered as a promising technology to support the higher data throughput.In an MDM system...The increasing amount of data exchange requires higher-capacity optical communication links.Mode division multiplexing(MDM)is considered as a promising technology to support the higher data throughput.In an MDM system,the mode generator and sorter are the backbone.However,most of the current schemes lack the programmability and universality,which makes the MDM link susceptible to the mode crosstalk and environmental disturbances.In this paper,we propose an intelligent multimode optical communication link using universal mode processing(generation and sorting)chips.The mode processor consists of a programmable 4×4 Mach Zehnder interferometer(MZI)network and can be intelligently configured to generate or sort both quasi linearly polarized(LP)modes and orbital angular momentum(OAM)modes in any desired routing state.We experimentally establish a chip-to-chip MDM communication system.The mode basis can be freely switched between four LP modes and four OAM modes.We also demonstrate the multimode optical communication capability at a data rate of 25 Gbit/s.The proposed scheme shows significant advantages in terms of universality,intelligence,programmability and resistance to mode crosstalk,environmental disturbances,and fabrication errors,demonstrating that the MZI-based reconfigurable mode processor chip has great potential in longdistance chip-to-chip multimode optical communication systems.展开更多
基金supported by the National Natural Science Foundation of China(No.20973142)the NSFC Innovation Group of Interfacial Electrochemistry(No.21021002)National Project 985 of High Education,New Faculty Starting Package of Xiamen University
文摘Here we report a novel generation/collection operation mode of scanning electrochemical microscopy,in which a theta micropipette was employed to support two adjacent water/1,2-dichloroethane interfaces separated by the thin central glass wall：one acts as the generator while the other as the collector.The generation current,collection current and collection efficiency were enhanced significantly when the tip approached to an insulate substrate.
文摘VLF （very low frequency） mode instability with parallel AC electric field was studied for generalized loss-cone distribution with an index j, which is reducible to bi-Maxwellian, loss- cone and delta function for j = 0, 1 and co. The particle trajectories and dispersion relation are obtained through a kinetic approach and method of characteristic solutions. The calculations are compared with the observations of low frequency waves of Voyager 2. The growth rate of plasma parameters suited to magnetosphere of Uranus is obtained. It is inferred that the magnitude as well as frequency of AC （alternating current） field increases the growth rate and widen the band width significantly. In addition to temperature anisotropy, particles in plasma having generalized loss-cone distribution provide an additional source of energy.
文摘The provision mode of the telecommunication service has experienced an evolving process, and showing the developing trend from distributed to centralized, from integrated to separated, and from closed to open. To suit this trend, there will be three provision modes as Session Initiation Protocol (SIP) server, Open Service Access (OSA) application server and intelligent network(IN) in Next Generation Network (NGN), provides all kinds of services and applications to the subscribers. With the popularity of broadband access and Internet, the NGN will provide single telecommunication service and act as the important national infrastructure to offer various information services to the subscribers. The service provision mode will be more open, diversified, and individualized.
基金funded by the National Major Science and Technology Projects of China(Grant No.2016ZX05006-004)the Sichuan Youth Science and Technology Foundation(Grant No.2016JQ0043)the National Natural Science Foundation of China(Grant No.41972144)
文摘With the increasing exploration and development of typical hydrocarbon-rich depressions,such as the Dongpu Depression,the exploitation difficulty of shallow formations is increasing.There is an urgent need to clarify the hydrocarbon generation mode and hydrocarbon generation histories in deep formations.In this study,a gold tube-autoclave closed system was used to simulate the hydrocarbon generation processes and establish the hydrocarbon generation mode of different types of kerogen.Then,constrained by the thermal history and hydrocarbon generation kinetics,hydrocarbon generation histories were modeled.The results show that hydrocarbon generation evolution can be divided into five stages,and the maturity of each stage is different.The hydrocarbon generation history of the source rocks of the Shahejie 3 Formation mainly dates from the early depositional period of the Shahejie 1 Formation to the middle depositional period of the Dongying Formation.Hydrocarbon generation history constrained by thermal history and hydrocarbon generation kinetics is more in line with actual geological conditions.Moreover,this research can provide important hydrocarbon generation parameters for deep oil and gas exploration and exploitation of the Shahejie 3 Formation in the Dongpu Depression.
文摘Evolutionary algorithms have been extensively utilized in practical applications.However,manually designed population updating formulas are inherently prone to the subjective influence of the designer.Genetic programming(GP),characterized by its tree-based solution structure,is a widely adopted technique for optimizing the structure of mathematical models tailored to real-world problems.This paper introduces a GP-based framework(GPEAs)for the autonomous generation of update formulas,aiming to reduce human intervention.Partial modifications to tree-based GP have been instigated,encompassing adjustments to its initialization process and fundamental update operations such as crossover and mutation within the algorithm.By designing suitable function sets and terminal sets tailored to the selected evolutionary algorithm,and ultimately derive an improved update formula.The Cat Swarm Optimization Algorithm(CSO)is chosen as a case study,and the GP-EAs is employed to regenerate the speed update formulas of the CSO.To validate the feasibility of the GP-EAs,the comprehensive performance of the enhanced algorithm(GP-CSO)was evaluated on the CEC2017 benchmark suite.Furthermore,GP-CSO is applied to deduce suitable embedding factors,thereby improving the robustness of the digital watermarking process.The experimental results indicate that the update formulas generated through training with GP-EAs possess excellent performance scalability and practical application proficiency.
文摘In connection with the current prospect of decarbonization of coal energy through the use of small nuclear power plants (SNPPs) at existing TPPs as heat sources for heat supply to municipal heating networks, there is a technological need to improve heat supply schemes to increase their environmental friendliness and efficiency. The paper proves the feasibility of using the heat-feeding mode of ASHPs for urban heat supply by heating the network water with steam taken from the turbine. The ratio of electric and thermal power of a “nuclear” combined heat and power plant is given. The advantage of using a heat pump, which provides twice as much electrical power with the same heat output, is established. Taking into account that heat in these modes is supplied with different potential, the energy efficiency was used to compare these options. To increase the heat supply capacity, a scheme with the use of a high-pressure heater in the backpressure mode and with the heating of network water with hot steam was proposed. Heat supply from ASHPs is efficient and environmentally friendly even in the case of significant remoteness of heat consumers.
基金provided by the Italian Presidenza del Consiglio dei Ministri-Dipartimento della Protezione Civile(DPC) within the INGV-DPC 2007-2009 agreement(project S1),Sapienza University and CNR-EurocoresTopoEurope
文摘We propose that the brittle-ductile transition （BDT） controls the seismic cycle. In particular, the movements detected by space geodesy record the steady state deformation in the ductile lower crust, whereas the stick-slip behavior of the brittle upper crust is constrained by its larger friction. GPS data allow analyzing the strain rate along active plate boundaries. In all tectonic settings, we propose that earthquakes primarily occur along active fault segments characterized by relative minima of strain rate, segments which are locked or slowly creeping. We discuss regional examples where large earthquakes happened in areas of relative low strain rate. Regardless the tectonic style, the interseismic stress and strain pattern inverts during the coseismic stage. Where a dilated band formed during the interseismic stage, this will be shortened at the coseismic stage, and vice-versa what was previously shortened, it will be dilated. The interseismic energy accumulation and the coseismic expenditure rather depend on the tectonic setting （extensional, contractional, or strike-slip）. The gravitational potential energy dominates along normal faults, whereas the elastic energy prevails for thrust earthquakes and performs work against the gravity force. The energy budget in strike-slip tectonic setting is also primarily due elastic energy. Therefore, precursors may be different as a function of the tectonic setting. In this model, with a given displacement, the magnitude of an earthquake results from the coseismic slip of the deformed volume above the BDT rather than only on the fault length, and it also depends on the fault kinematics.
基金This work was supported by the Department of Science and Technology(DST),India(No.DST/CERI/MI/SG/2017/080).
文摘In a grid-integrated photovoltaic system(GIPVS),there exist issues such as surplus active power and inadequate performance of maximum power point tracking(MPPT).A surplus active power causes the overvoltage problem at the point of common coupling in low-or medium-voltage grid during the peak hours of power generation.Additionally,the inadequate performance of the MPPT algorithm results in power loss due to high settling time during the sudden change of irradiance.Therefore,to solve the surplus power problem,the curtailment of active power is suggested with improved MPPT algorithm under variable irradiance conditions.In this paper,a derated power generation mode(DPGM)control strategy is presented for the curtailment of active power.Additionally,a drift-free(named as modified)perturb and observe(P&O)technique is also proposed to improve the performance of the MPPT algorithm.Consequently,the DPGM control scheme with the intermediate boost converter shaves the surplus active power during the peak hours of power generation.Furthermore,the modified MPPT algorithm deals with the fluctuation of irradiance during non-peak hours.Thus,the proposed control scheme delivers in a more efficient system during the peak hours of power generation.In addition,it reduces the power loss and settling time during the change of irradiance for non-peak hours.Based on the proposed control scheme,a 30 kW system has been simulated in MATLAB/Simulink using Simpower tools under different environmental conditions.
基金supported by the National Natural Science Foundation of China(No.61275206)the National "973" Project of China(No.2014CB921300)
文摘A laser-diode end-pumped Nd：YVO4 crystal laser is demonstrated to emit the first-order Laguerre- Gaussian （LGm） mode with 502-mW laser power and 22% slope efficiency. Tile LGm-mode is lased only when the pumping area locates in the central part of the laser crystal＇s front surface, and thereafter the symmetrical LGm-HGol-TEM00 mode transition happens when laser crystal is moved laterally inside several-tens-micron area. The possible mechanism responsible for the phenomenon of symmetrical mode transition is also discussed.
基金National Basic Research Program of China(2014CB340102)National Natural Science Foundation of China(NSFC)(61427813,61531003,61690195)
文摘Transverse mode characteristics of a laser are related to a variety of interesting applications. An on-demand mode solid laser in the 1064 nm band was proposed previously. In this paper, we provide a fiber laser for on-demand modes in the 1550 nm band to prescribe the pure and high-quality emission of a higher-order transverse laser mode, based on a simple construction with one spatial light modulator(SLM) and a single-mode erbium-doped fiber(SM-EDF). The SLM is designated to generate the desired higher-order mode and separate the higher-order mode and the fundamental mode. The fundamental mode oscillates in the fiber ring laser, and therefore the SM-EDF can be pumped with a single-mode 980 nm laser, no matter what higher-order mode is prescribed.In this proof-of-principle experiment, high-quality higher-order modes are observed from LP01 to LP105.Stable emission and real-time switching between modes can be easily realized by altering the phase on the SLM. In addition, the propagation of the LP_(01), LP_(11), LP_(21), and LP_(02) modes from the fiber laser is also demonstrated in a four-mode few-mode fiber.
基金the National Natural Science Foundation of China(No.10004016).
文摘A technique for analyzing the nonlinear generation of the cumulative second har-monics of generalized Lamb modes in a layered planar structure is developed. A theoretical model for nonlinear generalized Lamb mode propagation in a layered planar structure has been established, based on a partial plane wave approach. The nonlinearity is treated as a second-order perturbation of the linear elastic response. This model reveals some interesting features of the physics of the cumulative second harmonic generation. Although Lamb mode propagation is dispersive in a layered structure, the results of this analysis show that the amplitudes of the second harmonics do accumulate with propagation distance under certain special conditions. On the basis of the boundary and initial conditions of excitation, the formal solution of the cumulative second harmonic has been derived. Using the formal solution, we have performed some numerical simulations and obtained the cumulative second harmonic field patterns, illus-trating the distortion effect along the propagation distance, as well as the dependence of the field patterns on the position of the excitation source.
基金National Natural Science Foundation of China(62275088,62075075,U21A20511)Innovation Project of Optics Valley Laboratory(Grant No.OVL2021BG001)+1 种基金Research Grants Council,University Grants Committee of Hong Kong SAR under Grant PolyU15301022Knowledge Innovation Program of Wuhan-Basic Research 2023010201010049.
文摘The increasing amount of data exchange requires higher-capacity optical communication links.Mode division multiplexing(MDM)is considered as a promising technology to support the higher data throughput.In an MDM system,the mode generator and sorter are the backbone.However,most of the current schemes lack the programmability and universality,which makes the MDM link susceptible to the mode crosstalk and environmental disturbances.In this paper,we propose an intelligent multimode optical communication link using universal mode processing(generation and sorting)chips.The mode processor consists of a programmable 4×4 Mach Zehnder interferometer(MZI)network and can be intelligently configured to generate or sort both quasi linearly polarized(LP)modes and orbital angular momentum(OAM)modes in any desired routing state.We experimentally establish a chip-to-chip MDM communication system.The mode basis can be freely switched between four LP modes and four OAM modes.We also demonstrate the multimode optical communication capability at a data rate of 25 Gbit/s.The proposed scheme shows significant advantages in terms of universality,intelligence,programmability and resistance to mode crosstalk,environmental disturbances,and fabrication errors,demonstrating that the MZI-based reconfigurable mode processor chip has great potential in longdistance chip-to-chip multimode optical communication systems.
