With the projected global surge in hydrogen demand, driven by increasing applications and the imperative for low-emission hydrogen, the integration of machine learning(ML) across the hydrogen energy value chain is a c...With the projected global surge in hydrogen demand, driven by increasing applications and the imperative for low-emission hydrogen, the integration of machine learning(ML) across the hydrogen energy value chain is a compelling avenue. This review uniquely focuses on harnessing the synergy between ML and computational modeling(CM) or optimization tools, as well as integrating multiple ML techniques with CM, for the synthesis of diverse hydrogen evolution reaction(HER) catalysts and various hydrogen production processes(HPPs). Furthermore, this review addresses a notable gap in the literature by offering insights, analyzing challenges, and identifying research prospects and opportunities for sustainable hydrogen production. While the literature reflects a promising landscape for ML applications in hydrogen energy domains, transitioning AI-based algorithms from controlled environments to real-world applications poses significant challenges. Hence, this comprehensive review delves into the technical,practical, and ethical considerations associated with the application of ML in HER catalyst development and HPP optimization. Overall, this review provides guidance for unlocking the transformative potential of ML in enhancing prediction efficiency and sustainability in the hydrogen production sector.展开更多
Assuming that oil price follows the stochastic processes of Geometric Brownian Motion （GBM） or the Mean-Reverting Process （MRP）, this paper takes the net present value （NPV） as an economic index and models the P...Assuming that oil price follows the stochastic processes of Geometric Brownian Motion （GBM） or the Mean-Reverting Process （MRP）, this paper takes the net present value （NPV） as an economic index and models the PSC in 11 different scenarios by changing the value of each contract element （i.e. royalty, cost oil, profit oil as well as income tax）. Then the NPVs are shown in probability density graphs to investigate the effect of different elements on contract economics. The results show that under oil price uncertainty the influence of profit oil and income tax on NPV are more significant than those of royalty and cost oil, while a tax holiday could improve the contractor＇s financial status remarkably. Results also show that MRP is more appropriate for cases with low future oil price volatility, and GBM is best for high future oil price volatility.展开更多
The change and control of nitrogen content in molten steel was investigated through the production process of "LDBAr-LF-RH-CC". Results show that nitrogen content reduces gradually in converter-steelmaking s...The change and control of nitrogen content in molten steel was investigated through the production process of "LDBAr-LF-RH-CC". Results show that nitrogen content reduces gradually in converter-steelmaking stage, rises rapidly from the end of converter process to the end of argon station process, continues to increase in ladle furnace process, and decreases slightly in RH refining stage. Since nitrogen is removed mainly by BOF steelmaking and vacuum refining operations, nitrogen in molten steel should be removed as much as possible in these two operations. However, nitrogen uptake should be minimized in other operations of molten steel production process.展开更多
The entropy production rate of stationary minimal diffusion processes with smooth coefficients is calculated. As a byproduct, the continuity of paths of the minimal diffusion processes is discussed, and that the point...The entropy production rate of stationary minimal diffusion processes with smooth coefficients is calculated. As a byproduct, the continuity of paths of the minimal diffusion processes is discussed, and that the point at infinity is absorbing is proved.展开更多
Based on the comparison of several methods of time series predicting, this paper points out that it is necessary to use dynamic neural network in modeling of complex production process. Because self feedback and mutua...Based on the comparison of several methods of time series predicting, this paper points out that it is necessary to use dynamic neural network in modeling of complex production process. Because self feedback and mutual feedback are adopted among nodes at the same layer in Elman network, it has stronger ability of dynamic approximation, and can describe any non linear dynamic system. After the structure and mathematical description being given, dynamic back propagation (BP) algorithm of training weights of Elman neural network is deduced. At last, the network is used to predict ash content of black amber in jigging production process. The results show that this neural network is powerful in predicting and suitable for modeling, predicting, and controling of complex production process.展开更多
Production planning under flexible job shop environment is studied.A mathematic model is formulated to help improve alternative process production.This model,in which genetic algorithm is used,is expected to result in...Production planning under flexible job shop environment is studied.A mathematic model is formulated to help improve alternative process production.This model,in which genetic algorithm is used,is expected to result in better production planning,hence towards the aim of minimizing production cost under the constraints of delivery time and other scheduling conditions.By means of this algorithm,all planning schemes which could meet all requirements of the constraints within the whole solution space are exhaustively searched so as to find the optimal one.Also,a case study is given in the end to support and validate this model.Our results show that genetic algorithm is capable of locating feasible process routes to reduce production cost for certain tasks.展开更多
Taking into account the effects of shadowing and jet quenching, the large transverse momentum distribution of K＋, π＋ and K＋/π＋ ratios at s = 200 GeV originating from resolved photoproduction processes is calcula...Taking into account the effects of shadowing and jet quenching, the large transverse momentum distribution of K＋, π＋ and K＋/π＋ ratios at s = 200 GeV originating from resolved photoproduction processes is calculated based on perturbative quantum chromodynamics. It is found that the contribution of K＋ and π＋ produced by photoproduction processes is evident. The K＋ /π＋ ratios in Au-Au collisions show an obvious enhancement compared with p p collisions. The numerical results indicate that the photoproduetion processes are good modification for kaon and pion production.展开更多
An integration process of vacuum residue FCC(VRFCC)and moderate pressure hydro cracking(RMC),developed by RIPP and BDI,opens a new route for maximizing production of both high value products and the feed for steam cra...An integration process of vacuum residue FCC(VRFCC)and moderate pressure hydro cracking(RMC),developed by RIPP and BDI,opens a new route for maximizing production of both high value products and the feed for steam cracking(SC).VRFCC technology has been put on stream at Yanshan Petrochemical Co (YPC)since November 1998.A 79 2%(mass percent)high value product(LPG+GSL+LCO)was surprisingly made on the test run from a resid feedstock of 85 0%(mass percent)Daqing crude VR content.No facility coking was found during the operation.RMC is a renovating moderate pressure hydrocracking technology,the end point of the heavy VGO feed is as high as 534 ℃,and the RMC catalyst performance shows high hydrodenitrogenation activity and high ring opening selectivity.The process highlights the flexibility of product slates——maximum premium mid distillates yield(38 0%(mass percent))and/or maximum hydro unconverted bottoms(Hydro BTMs)yield(50%～70%(mass percent)).Over 30%(mass percent)ethylene was produced from SC process based on Hydro BTMs feed. The application of VRFCC/RMC integration at YPC not only covers the shortages of SC feed for 660 kt/a ethylene production capacity,but also increases the total yield of premium fuel products.展开更多
Since bamboo has the advantages of straight grain, beautiful color, high strength and toughness, and excellent abrasion resistance, bamboo-based panels have been widely used in the fields of vehicle, construction, shi...Since bamboo has the advantages of straight grain, beautiful color, high strength and toughness, and excellent abrasion resistance, bamboo-based panels have been widely used in the fields of vehicle, construction, ship building, furniture, and decoration to partly take the place of wood, steel, plastic etc in China. This paper briefly described the basic component units, including strip, sliver, and particle, of bamboo-based panel and pointed out that to design the structure of bamboo-based panels should follow the principle of symmetric structure, surface forming method, and structuring principle of equalizing stress. According to the processing methods and formation of component units, the authors classified the bamboo-based panels in China into 13 types and presented the manufacturing technique and uses of the bamboo products, such as plybamboo, bamboo flooring, and bamboo-wood composite products in detail. In the last part of the paper, much information were offered on the output, market, and selling prospect of each type of bamboo-based panels.展开更多
This study presents an overview of the current status of hydrogen production in relation to the global requirement for energy and resources.Subsequently,it symmetrically outlines the advantages and disadvantages of va...This study presents an overview of the current status of hydrogen production in relation to the global requirement for energy and resources.Subsequently,it symmetrically outlines the advantages and disadvantages of various production routes including fossil fuel/biomass conversion,water electrolysis,microbial fermentation,and photocatalysis(PC),in terms of their technologies,economy,energy consumption,and costs.Considering the characteristics of hydrogen energy and the current infrastructure issues,it highlights that onsite production is indispensable and convenient for some special occasions.Finally,it briefly summarizes the current industrialization situation and presents future development and research directions,such as theoretical research strengthening,renewable raw material development,process coupling,and sustainable energy use.展开更多
Coal fly ash(FA),a valuable industrial solid residue generated from coal combustion,is composed of various metal oxides and has a high thermal stability.Given that the coal-based energy will continue to account for a ...Coal fly ash(FA),a valuable industrial solid residue generated from coal combustion,is composed of various metal oxides and has a high thermal stability.Given that the coal-based energy will continue to account for a significant portion of global electricity generation in the coming years,the lack of effective management strategies exacerbates the threat of FA wastes to the surrounding environment and human health.For a sustainable development,green and renewable hydrogen economy and CO_(2)capture efforts provide appealing opportunities to valorize FA as catalysts and/or sorbents due to their appealing physicochemical properties.Hydrogen applications along with carbon neutrality are potential strategies to mitigate climate change crisis,but high processing costs(catalysts/sorbents)are challenging to realize this purpose.In this context,the utilization of FA not only enhances industrial competitiveness(by reducing manufacturing costs),but also provides ecologically friendly approaches to minimizing this solid waste.This state-of-the-art review highlights a wide-ranging outlook on the valorization of FA as catalysts and sorbents for hydrogen-rich gas production via conventional/intensified processes(CO_(2)/H_(2)O reforming,ammonia decomposition,hydride hydrolysis).The fundamental physicochemical characterizations and hazards/utilization of FA,which significantly affect the FA's utilization in various fields,are first introduced.The influence of several factors(like FA types and catalysis/sorption operation conditions)on the activity performance of FA-based materials is then discussed in detail.This critical review aims to open the window to further innovative ideas regarding the application of different FA residues in other catalytic and sorption processes.展开更多
From 1980’s decade,the introduction of carbon composite materials in structural applications has been consistently increased in the successive generations of civil aircraft from Single Aisle to Middle-long Range to a...From 1980’s decade,the introduction of carbon composite materials in structural applications has been consistently increased in the successive generations of civil aircraft from Single Aisle to Middle-long Range to achieve a culminant point with more than 50%in structure weight in recent commercial civil aircraft.This evolution,done through successive iterations,has been possible by combining in the same time the improvement of intrinsic composite material performances and its transformation into prepreg production technologies together with the development of new manufacturing process for material lay-up automation at composite shop-floor manufacturer of aircraft composite parts.New challenges are still coming to continuously develop materials and technologies in order to pursue the production more cost-effective composite parts.Associated to higher aircraft production rate for single aisle,new challenges may force material and aircraft designers and producers to furthermore drive new products and processes introduction and new ways of transformation within in next decade of composite aircraft designs.We propose to illustrate these trends using past and recent developments and our return of experience from Hexcel on Civil Aircraft programs.展开更多
A diamond-like carbon circular target is proposed to improve γ-ray emission and pair production with a laser intensity of 8×1022 W cm-2by using 2D particle-in-cell simulations with quantum electrodynamics.It is ...A diamond-like carbon circular target is proposed to improve γ-ray emission and pair production with a laser intensity of 8×1022 W cm-2by using 2D particle-in-cell simulations with quantum electrodynamics.It is found that the circular target can enhance the density of γ-photons significantly more than a plane target, when two colliding circularly polarized lasers irradiate the target.By multi-laser irradiating the circular target, the optical trap of lasers can prevent the high energy electrons accelerated by laser radiation pressure from escaping.Hence, γ-photons with a high density of beyond 5000 ncare obtained through nonlinear Compton backscattering.Meanwhile, 2.7×1011 positrons with an average energy of 230 MeV are achieved via the multiphoton Breit-Wheeler process.Such an ultrabright γ-ray source and dense positron source can be useful in many applications.The optimal target radius and laser mismatching deviation parameters are also discussed in detail.展开更多
To prevent the long-time coherent integration and limited range window stumbling blocks of stretch processing and reduce computational complexity, a novel method called multi-subpulse process of large time-bandwidth p...To prevent the long-time coherent integration and limited range window stumbling blocks of stretch processing and reduce computational complexity, a novel method called multi-subpulse process of large time-bandwidth product linear frequency modulating （ LFM ） signal （ i. e. chirp ） is proposed in this paper. The wideband chirp signal is split up into several compressed subpulses. Then the fast Fourier transform （FFT） is used to reconstruct the high resolution range profile （ HR- RP） in a relative short computation time. For multi-frame, pulse Doppler （PD） process is performed to obtain the two-dimension range-Doppler （R-D） high resolution profile. Simulations and field ex- perimental results show that the proposed method can provide high-quality target profile over a large range window in a short computation time and has the promising potential for long-time coherent in- tegration.展开更多
The oxygen initiation process,one of the key processes in the early stage of the autothermic pyrolysis insitu conversion technology,has not been deeply investigated,which seriously limits its development.In this study...The oxygen initiation process,one of the key processes in the early stage of the autothermic pyrolysis insitu conversion technology,has not been deeply investigated,which seriously limits its development.In this study,the reaction behaviors,kinetic parameters,heat and product release characteristics during the isothermal oxygen initiation process of Huadian oil shale in O2/N2mixtures with different oxygen concentrations and initiation temperatures were investigated via TG/DSC-FTIR.The results show that the samples exhibit three different reaction behaviors during the initiation stage,consisting of two main parts,i.e.,the oxidative weight-gain and the oxidative reaction phases.The former phase is mainly characterized by the oxygen addition reaction that produces oxidizing groups which increase the sample mass.And the latter stage consists of two main subreactions.The first subreaction involves the oxidative cracking and pyrolysis of oxidizing groups and kerogen to produce fuel deposits such as residual carbon,while the second subreaction focuses on the oxidation of the resulting fuels.Furthermore,increasing the oxygen concentration significantly promotes the above reactions,leading to an increase in the reaction intensity and reaction rate.Owing to the combined effect of oxygen concentration and residual organic matter content,the total heat release increases with the increasing initiation temperature and reaches its maximum at 330-370℃.In addition,the preheating stage primarily produces hydrocarbon gases,while the initiation stage predominantly generates CO_(2).As the preheating temperature increases,the CO_(2)output intensifies,the required reaction time shortens,and the release becomes more concentrated.Based on these findings,a reaction mechanism for the oxygen initiation process of Huadian oil shale was proposed,and recommendations were provided for optimizing the construction process.展开更多
基金express their gratitude to the Higher Institution Centre of Excellence (HICoE) fund under the project code (JPT.S(BPKI)2000/016/018/015JId.4(21)/2022002HICOE)Universiti Tenaga Nasional (UNITEN) for funding the research through the (J510050002–IC–6 BOLDREFRESH2025)Akaun Amanah Industri Bekalan Elektrik (AAIBE) Chair of Renewable Energy grant,and NEC Energy Transition Grant (202203003ETG)。
文摘With the projected global surge in hydrogen demand, driven by increasing applications and the imperative for low-emission hydrogen, the integration of machine learning(ML) across the hydrogen energy value chain is a compelling avenue. This review uniquely focuses on harnessing the synergy between ML and computational modeling(CM) or optimization tools, as well as integrating multiple ML techniques with CM, for the synthesis of diverse hydrogen evolution reaction(HER) catalysts and various hydrogen production processes(HPPs). Furthermore, this review addresses a notable gap in the literature by offering insights, analyzing challenges, and identifying research prospects and opportunities for sustainable hydrogen production. While the literature reflects a promising landscape for ML applications in hydrogen energy domains, transitioning AI-based algorithms from controlled environments to real-world applications poses significant challenges. Hence, this comprehensive review delves into the technical,practical, and ethical considerations associated with the application of ML in HER catalyst development and HPP optimization. Overall, this review provides guidance for unlocking the transformative potential of ML in enhancing prediction efficiency and sustainability in the hydrogen production sector.
基金financial support from Key Projects of Philosophy and Social Sciences Research of Ministry of Education (09JZD0038)
文摘Assuming that oil price follows the stochastic processes of Geometric Brownian Motion （GBM） or the Mean-Reverting Process （MRP）, this paper takes the net present value （NPV） as an economic index and models the PSC in 11 different scenarios by changing the value of each contract element （i.e. royalty, cost oil, profit oil as well as income tax）. Then the NPVs are shown in probability density graphs to investigate the effect of different elements on contract economics. The results show that under oil price uncertainty the influence of profit oil and income tax on NPV are more significant than those of royalty and cost oil, while a tax holiday could improve the contractor＇s financial status remarkably. Results also show that MRP is more appropriate for cases with low future oil price volatility, and GBM is best for high future oil price volatility.
文摘The change and control of nitrogen content in molten steel was investigated through the production process of "LDBAr-LF-RH-CC". Results show that nitrogen content reduces gradually in converter-steelmaking stage, rises rapidly from the end of converter process to the end of argon station process, continues to increase in ladle furnace process, and decreases slightly in RH refining stage. Since nitrogen is removed mainly by BOF steelmaking and vacuum refining operations, nitrogen in molten steel should be removed as much as possible in these two operations. However, nitrogen uptake should be minimized in other operations of molten steel production process.
基金This work is supported by NSFC (10271008 and 10531070)
文摘The entropy production rate of stationary minimal diffusion processes with smooth coefficients is calculated. As a byproduct, the continuity of paths of the minimal diffusion processes is discussed, and that the point at infinity is absorbing is proved.
文摘Based on the comparison of several methods of time series predicting, this paper points out that it is necessary to use dynamic neural network in modeling of complex production process. Because self feedback and mutual feedback are adopted among nodes at the same layer in Elman network, it has stronger ability of dynamic approximation, and can describe any non linear dynamic system. After the structure and mathematical description being given, dynamic back propagation (BP) algorithm of training weights of Elman neural network is deduced. At last, the network is used to predict ash content of black amber in jigging production process. The results show that this neural network is powerful in predicting and suitable for modeling, predicting, and controling of complex production process.
基金Sponsored by Key Subject Foundation of Beijing Municipal(XK100070530)
文摘Production planning under flexible job shop environment is studied.A mathematic model is formulated to help improve alternative process production.This model,in which genetic algorithm is used,is expected to result in better production planning,hence towards the aim of minimizing production cost under the constraints of delivery time and other scheduling conditions.By means of this algorithm,all planning schemes which could meet all requirements of the constraints within the whole solution space are exhaustively searched so as to find the optimal one.Also,a case study is given in the end to support and validate this model.Our results show that genetic algorithm is capable of locating feasible process routes to reduce production cost for certain tasks.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11065010 and 11465021
文摘Taking into account the effects of shadowing and jet quenching, the large transverse momentum distribution of K＋, π＋ and K＋/π＋ ratios at s = 200 GeV originating from resolved photoproduction processes is calculated based on perturbative quantum chromodynamics. It is found that the contribution of K＋ and π＋ produced by photoproduction processes is evident. The K＋ /π＋ ratios in Au-Au collisions show an obvious enhancement compared with p p collisions. The numerical results indicate that the photoproduetion processes are good modification for kaon and pion production.
文摘An integration process of vacuum residue FCC(VRFCC)and moderate pressure hydro cracking(RMC),developed by RIPP and BDI,opens a new route for maximizing production of both high value products and the feed for steam cracking(SC).VRFCC technology has been put on stream at Yanshan Petrochemical Co (YPC)since November 1998.A 79 2%(mass percent)high value product(LPG+GSL+LCO)was surprisingly made on the test run from a resid feedstock of 85 0%(mass percent)Daqing crude VR content.No facility coking was found during the operation.RMC is a renovating moderate pressure hydrocracking technology,the end point of the heavy VGO feed is as high as 534 ℃,and the RMC catalyst performance shows high hydrodenitrogenation activity and high ring opening selectivity.The process highlights the flexibility of product slates——maximum premium mid distillates yield(38 0%(mass percent))and/or maximum hydro unconverted bottoms(Hydro BTMs)yield(50%～70%(mass percent)).Over 30%(mass percent)ethylene was produced from SC process based on Hydro BTMs feed. The application of VRFCC/RMC integration at YPC not only covers the shortages of SC feed for 660 kt/a ethylene production capacity,but also increases the total yield of premium fuel products.
基金This study was supported by National 9th-Five-Year Plan Project (No. 96-011-02-07-02).
文摘Since bamboo has the advantages of straight grain, beautiful color, high strength and toughness, and excellent abrasion resistance, bamboo-based panels have been widely used in the fields of vehicle, construction, ship building, furniture, and decoration to partly take the place of wood, steel, plastic etc in China. This paper briefly described the basic component units, including strip, sliver, and particle, of bamboo-based panel and pointed out that to design the structure of bamboo-based panels should follow the principle of symmetric structure, surface forming method, and structuring principle of equalizing stress. According to the processing methods and formation of component units, the authors classified the bamboo-based panels in China into 13 types and presented the manufacturing technique and uses of the bamboo products, such as plybamboo, bamboo flooring, and bamboo-wood composite products in detail. In the last part of the paper, much information were offered on the output, market, and selling prospect of each type of bamboo-based panels.
基金the National Natural Science Foundation of China under Grant No.20906063the Liaoning BaiQianWan Talents Program under Grant No.2018921046+1 种基金the Scientific Research Project of Liaoning Provincial Department of Education under Grant No.LJGD2020002the Shenyang Youth Science and Technology Project under Grant No.RC200325.
文摘This study presents an overview of the current status of hydrogen production in relation to the global requirement for energy and resources.Subsequently,it symmetrically outlines the advantages and disadvantages of various production routes including fossil fuel/biomass conversion,water electrolysis,microbial fermentation,and photocatalysis(PC),in terms of their technologies,economy,energy consumption,and costs.Considering the characteristics of hydrogen energy and the current infrastructure issues,it highlights that onsite production is indispensable and convenient for some special occasions.Finally,it briefly summarizes the current industrialization situation and presents future development and research directions,such as theoretical research strengthening,renewable raw material development,process coupling,and sustainable energy use.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)the China Scholarship Council(CSC,201708130079)。
文摘Coal fly ash(FA),a valuable industrial solid residue generated from coal combustion,is composed of various metal oxides and has a high thermal stability.Given that the coal-based energy will continue to account for a significant portion of global electricity generation in the coming years,the lack of effective management strategies exacerbates the threat of FA wastes to the surrounding environment and human health.For a sustainable development,green and renewable hydrogen economy and CO_(2)capture efforts provide appealing opportunities to valorize FA as catalysts and/or sorbents due to their appealing physicochemical properties.Hydrogen applications along with carbon neutrality are potential strategies to mitigate climate change crisis,but high processing costs(catalysts/sorbents)are challenging to realize this purpose.In this context,the utilization of FA not only enhances industrial competitiveness(by reducing manufacturing costs),but also provides ecologically friendly approaches to minimizing this solid waste.This state-of-the-art review highlights a wide-ranging outlook on the valorization of FA as catalysts and sorbents for hydrogen-rich gas production via conventional/intensified processes(CO_(2)/H_(2)O reforming,ammonia decomposition,hydride hydrolysis).The fundamental physicochemical characterizations and hazards/utilization of FA,which significantly affect the FA's utilization in various fields,are first introduced.The influence of several factors(like FA types and catalysis/sorption operation conditions)on the activity performance of FA-based materials is then discussed in detail.This critical review aims to open the window to further innovative ideas regarding the application of different FA residues in other catalytic and sorption processes.
文摘From 1980’s decade,the introduction of carbon composite materials in structural applications has been consistently increased in the successive generations of civil aircraft from Single Aisle to Middle-long Range to achieve a culminant point with more than 50%in structure weight in recent commercial civil aircraft.This evolution,done through successive iterations,has been possible by combining in the same time the improvement of intrinsic composite material performances and its transformation into prepreg production technologies together with the development of new manufacturing process for material lay-up automation at composite shop-floor manufacturer of aircraft composite parts.New challenges are still coming to continuously develop materials and technologies in order to pursue the production more cost-effective composite parts.Associated to higher aircraft production rate for single aisle,new challenges may force material and aircraft designers and producers to furthermore drive new products and processes introduction and new ways of transformation within in next decade of composite aircraft designs.We propose to illustrate these trends using past and recent developments and our return of experience from Hexcel on Civil Aircraft programs.
基金supported by the National Natural Science Foundation of China (Nos.11875007, 11305010)supported by the STFC Cockcroft Institute core grant
文摘A diamond-like carbon circular target is proposed to improve γ-ray emission and pair production with a laser intensity of 8×1022 W cm-2by using 2D particle-in-cell simulations with quantum electrodynamics.It is found that the circular target can enhance the density of γ-photons significantly more than a plane target, when two colliding circularly polarized lasers irradiate the target.By multi-laser irradiating the circular target, the optical trap of lasers can prevent the high energy electrons accelerated by laser radiation pressure from escaping.Hence, γ-photons with a high density of beyond 5000 ncare obtained through nonlinear Compton backscattering.Meanwhile, 2.7×1011 positrons with an average energy of 230 MeV are achieved via the multiphoton Breit-Wheeler process.Such an ultrabright γ-ray source and dense positron source can be useful in many applications.The optimal target radius and laser mismatching deviation parameters are also discussed in detail.
基金Supported by the National Natural Science Foundation of China(61301189)
文摘To prevent the long-time coherent integration and limited range window stumbling blocks of stretch processing and reduce computational complexity, a novel method called multi-subpulse process of large time-bandwidth product linear frequency modulating （ LFM ） signal （ i. e. chirp ） is proposed in this paper. The wideband chirp signal is split up into several compressed subpulses. Then the fast Fourier transform （FFT） is used to reconstruct the high resolution range profile （ HR- RP） in a relative short computation time. For multi-frame, pulse Doppler （PD） process is performed to obtain the two-dimension range-Doppler （R-D） high resolution profile. Simulations and field ex- perimental results show that the proposed method can provide high-quality target profile over a large range window in a short computation time and has the promising potential for long-time coherent in- tegration.
基金supported by the China Postdoctoral Science Foundation under Grant Number 2023M743305the National Funding Program for Postdoctoral Fellows(GZC20232484)+2 种基金the National Key R&D Program of China(No.2019YFA0705502,2019YFA0705501)the Young and Middle-aged Excellent Team Project for Scientific and Technological Innovation of Jilin Province,Chinathe National Natural Science Foundation of China(42202345)。
文摘The oxygen initiation process,one of the key processes in the early stage of the autothermic pyrolysis insitu conversion technology,has not been deeply investigated,which seriously limits its development.In this study,the reaction behaviors,kinetic parameters,heat and product release characteristics during the isothermal oxygen initiation process of Huadian oil shale in O2/N2mixtures with different oxygen concentrations and initiation temperatures were investigated via TG/DSC-FTIR.The results show that the samples exhibit three different reaction behaviors during the initiation stage,consisting of two main parts,i.e.,the oxidative weight-gain and the oxidative reaction phases.The former phase is mainly characterized by the oxygen addition reaction that produces oxidizing groups which increase the sample mass.And the latter stage consists of two main subreactions.The first subreaction involves the oxidative cracking and pyrolysis of oxidizing groups and kerogen to produce fuel deposits such as residual carbon,while the second subreaction focuses on the oxidation of the resulting fuels.Furthermore,increasing the oxygen concentration significantly promotes the above reactions,leading to an increase in the reaction intensity and reaction rate.Owing to the combined effect of oxygen concentration and residual organic matter content,the total heat release increases with the increasing initiation temperature and reaches its maximum at 330-370℃.In addition,the preheating stage primarily produces hydrocarbon gases,while the initiation stage predominantly generates CO_(2).As the preheating temperature increases,the CO_(2)output intensifies,the required reaction time shortens,and the release becomes more concentrated.Based on these findings,a reaction mechanism for the oxygen initiation process of Huadian oil shale was proposed,and recommendations were provided for optimizing the construction process.
