Araneiforms are spider-like ground patterns that are widespread in the southern polar regions of Mars.A gas erosion process driven by the seasonal sublimation of CO_(2) ice was proposed as an explanation for their for...Araneiforms are spider-like ground patterns that are widespread in the southern polar regions of Mars.A gas erosion process driven by the seasonal sublimation of CO_(2) ice was proposed as an explanation for their formation,which cannot occur on Earth due to the high climatic temperature.In this study,we propose an alternative mechanism that attrib-utes the araneiform formation to the erosion of upwelling salt water from the subsurface,relying on the identification of the first terrestrial analog found in a playa of the Qaidam Basin on the northern Tibetan Plateau.Morphological analysis indicates that the structures in the Qaidam Basin have fractal features comparable to araneiforms on Mars.A numerical model is developed to investigate the araneiform formation driven by the water-diffusion mechanism.The simulation res-ults indicate that the water-diffusion process,under varying ground conditions,may be responsible for the diverse aranei-form morphologies observed on both Earth and Mars.Our numerical simulations also demonstrate that the orientations of the saltwater diffusion networks are controlled by pre-existing polygonal cracks,which is consistent with observations of araneiforms on Mars and Earth.Our study thus suggests that a saltwater-related origin of the araneiform is possible and has significant implications for water searches on Mars.展开更多
This paper investigates the channel diversity problem in high frequency(HF) communication systems. Due to the limited HF spectrum resources, a HF communication system with shared channels is considered, where each use...This paper investigates the channel diversity problem in high frequency(HF) communication systems. Due to the limited HF spectrum resources, a HF communication system with shared channels is considered, where each user equipment(UE) has individual communication demand. In order to maximize the communication probability of the whole system, a matching-potential game framework is designed. In detail, the channel diversity problem is decomposed into two sub-problems. One is channel-transmitter matching problem, which can be formulated as a many-to-one matching game. The other is the transmitter allocation problem which decides the transmission object that each transmitter communicates with under channel-transmitter matching result, and this sub-problem can be modeled as a potential game. A multiple round stable matching algorithm(MRSMA) is proposed, which obtains a stable matching result for the first sub-problem, and a distributed BR-based transmitter allocation algorithm(DBRTAA) is designed to reach Nash Equilibrium(NE) of the second sub-problem. Simulation results verify the effectiveness and superiority of the proposed method.展开更多
In order to obtain satisfactory mechanical properties for the cam used in high-power ship diesel engines, a new quenching technology was proposed by designing a two-stage quenching process with an alkaline bath as the...In order to obtain satisfactory mechanical properties for the cam used in high-power ship diesel engines, a new quenching technology was proposed by designing a two-stage quenching process with an alkaline bath as the quenching medium. To demonstrate the effectiveness of the proposed new quenching technology, both numerical analysis and experimental study were performed. The new quenching technology was analyzed using finite element method. The combined effects of the temperature, stress and microstructure fields were investigated considering nonlinear material properties. Finally, an experimental study was performed to verify the effectiveness of the proposed new quenching technology. The numerical results show that internal stress is affected by both thermal stress and transformation stress. In addition, the direction of the internal stress is changed several times due to thermal interaction and microstructure evolution during the quenching process. The experimental results show that the proposed new quenching technology significantly improves the mechanical properties and microstructures of the cam. The tensile strength, the impact resistance and the hardness value of the cam by the proposed new quenching technology are improved by 4.3%, 8.9% and 3.5% compared with those by the traditional quenching technology. Moreover, the residual stress and cam shape deformation are reduced by 40.0% and 48.9% respectively for the cam manufactured by the new quenching technology.展开更多
An expert system for biomass soft-sensor hybrid modeling in fermentation process was decribed in this paper.A production rules representation based on database was presented.The definitions of production rules for bio...An expert system for biomass soft-sensor hybrid modeling in fermentation process was decribed in this paper.A production rules representation based on database was presented.The definitions of production rules for biomass soft-sensor hybrid modeling knowledge were proposed.A knowledge base with layered structure was introduced.A breadth-first reasoning approach based on match degree(BFMD) was developed.The definition and calculation method of match degree were illustrated.Compared with the depth-first reasoning approach based on exhaustive method(DFEM),the BFMD needs fewer introduced variables.This expert system could reduce the reasoning steps effectively,and advance reasoning efficiency.Tests shows that reasoning efficiency of the expert system using BFMD in the knowledge base with layered structure is improved 12.9% averagely,compared with using DFEM in the knowledge base with ranking structure.展开更多
Biodiesel is a kind of clean and renewable energy. The effect of ethanol addition on the flame characteristics of waste oil biodiesel is studied by using OH-PLIF technique from the perspective of OH radical evolution....Biodiesel is a kind of clean and renewable energy. The effect of ethanol addition on the flame characteristics of waste oil biodiesel is studied by using OH-PLIF technique from the perspective of OH radical evolution. Ethanol addition leads to the appearance of diffusion flame reaction interface ahead of schedule and shortens the diffusion flame height. The experimental results show a linear correlation between the flame height and the fuel flow rate for a given fuel and oxidant. The same conclusion is drawn from the theoretical analysis of the approximate model. In addition. ethanol addition makes the average OH signal intensity of flame at different fuel flow rate tend to be consistent and the fuel flow rate enlarge where the flame field shows the strongest oxidation performance. Average OH signal intensity begins to weaken at larger fuel flow rate, which indicates that fuel flow rate of fuels blended with ethanol can change in larger range and does not significantly affect the uniformity of combustion.展开更多
A new generation conical spray system for conventional diesel engines or premixed combustion diesel engines is introduced. By means of oriented impingement method, flexible spray penetration in design is realized. Hig...A new generation conical spray system for conventional diesel engines or premixed combustion diesel engines is introduced. By means of oriented impingement method, flexible spray penetration in design is realized. High-speed photograph was used to investigate the spatial distribution characteristics of the new spray for cases of different impingement angles and needle valve opening pressures. The results show that, by applying spray impingement orientation, fuel jets spread along the cone surface as shape of sectors, so the dispersion of jets is increased obviously. Changing on impingement angle leads to variation of penetration, which is critical in homogeneous mixture preparation. Due to the flexibility of spray penetration in design, the spray impingement on liner is avoided in a great extent. The results also indicate that higher needle valve opening pressure results in longer penetration and larger spray angle after impingement. Combustion characteristics of the impinged conical spray were studied in the 1135 type diesel engine. The new impinged conical spray system work smoothly in full load range with better fuel economy and lower emissions of NOx and soot than the original test engine.展开更多
Research was undertaken to define the concept of a coach-based braking energy recoupment, storage and regeneration system to augment the acceleration of regional commuter trains hauled by diesel locomotives. Functiona...Research was undertaken to define the concept of a coach-based braking energy recoupment, storage and regeneration system to augment the acceleration of regional commuter trains hauled by diesel locomotives. Functional specifications were developed having the goal of increasing by 25% the acceleration rate of a train consisting of 10 bi-level coaches hauled by a 3,000 hp diesel locomotive, typical of the rolling stock now in commuter services in Canada and the USA. Examining three alternate hybrid system technologies for train retardation based, respectively, on hydrostatic, battery and ultracapacitor energy storage. The ultracapacitor hybrid system appeared the most promising due to the capability ofultracapacitors to repeatedly and rapidly accept large energy charges without degradation, temperature insensitive and flexible in the placement of modules in the limited space available. Analyses of train operation simulations showed that in addition to augmenting acceleration and reducing trip time, braking energy recoupment reduced fuel consumption and concomitant diesel emissions.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB41000000)the Fundamental Research Funds for the Central Universities(WK2080000144)。
文摘Araneiforms are spider-like ground patterns that are widespread in the southern polar regions of Mars.A gas erosion process driven by the seasonal sublimation of CO_(2) ice was proposed as an explanation for their formation,which cannot occur on Earth due to the high climatic temperature.In this study,we propose an alternative mechanism that attrib-utes the araneiform formation to the erosion of upwelling salt water from the subsurface,relying on the identification of the first terrestrial analog found in a playa of the Qaidam Basin on the northern Tibetan Plateau.Morphological analysis indicates that the structures in the Qaidam Basin have fractal features comparable to araneiforms on Mars.A numerical model is developed to investigate the araneiform formation driven by the water-diffusion mechanism.The simulation res-ults indicate that the water-diffusion process,under varying ground conditions,may be responsible for the diverse aranei-form morphologies observed on both Earth and Mars.Our numerical simulations also demonstrate that the orientations of the saltwater diffusion networks are controlled by pre-existing polygonal cracks,which is consistent with observations of araneiforms on Mars and Earth.Our study thus suggests that a saltwater-related origin of the araneiform is possible and has significant implications for water searches on Mars.
基金supported by the Natural Science Foundation for Distinguished Young Scholars of Jiangsu Province under Grant No. BK20160034in part by the National Natural Science Foundation of China under Grant No. 61671473 and No. 61631020in part by the Open Research Foundation of Science and Technology on Communication Networks Laboratory
文摘This paper investigates the channel diversity problem in high frequency(HF) communication systems. Due to the limited HF spectrum resources, a HF communication system with shared channels is considered, where each user equipment(UE) has individual communication demand. In order to maximize the communication probability of the whole system, a matching-potential game framework is designed. In detail, the channel diversity problem is decomposed into two sub-problems. One is channel-transmitter matching problem, which can be formulated as a many-to-one matching game. The other is the transmitter allocation problem which decides the transmission object that each transmitter communicates with under channel-transmitter matching result, and this sub-problem can be modeled as a potential game. A multiple round stable matching algorithm(MRSMA) is proposed, which obtains a stable matching result for the first sub-problem, and a distributed BR-based transmitter allocation algorithm(DBRTAA) is designed to reach Nash Equilibrium(NE) of the second sub-problem. Simulation results verify the effectiveness and superiority of the proposed method.
基金Project(50875268) supported by the National Natural Science Foundation of China Project(CSTC2008AB3057) supported by Foundation of Chongqing Science and Technology Commission, China+1 种基金 Project(108107) supported by the Key Project of Ministry of Education of China Project(50925518) supported by the National Science Fund for Distinguished Young Scholars
文摘In order to obtain satisfactory mechanical properties for the cam used in high-power ship diesel engines, a new quenching technology was proposed by designing a two-stage quenching process with an alkaline bath as the quenching medium. To demonstrate the effectiveness of the proposed new quenching technology, both numerical analysis and experimental study were performed. The new quenching technology was analyzed using finite element method. The combined effects of the temperature, stress and microstructure fields were investigated considering nonlinear material properties. Finally, an experimental study was performed to verify the effectiveness of the proposed new quenching technology. The numerical results show that internal stress is affected by both thermal stress and transformation stress. In addition, the direction of the internal stress is changed several times due to thermal interaction and microstructure evolution during the quenching process. The experimental results show that the proposed new quenching technology significantly improves the mechanical properties and microstructures of the cam. The tensile strength, the impact resistance and the hardness value of the cam by the proposed new quenching technology are improved by 4.3%, 8.9% and 3.5% compared with those by the traditional quenching technology. Moreover, the residual stress and cam shape deformation are reduced by 40.0% and 48.9% respectively for the cam manufactured by the new quenching technology.
基金National Natural Science Foundation of China (No. 20476007,No. 20676013)
文摘An expert system for biomass soft-sensor hybrid modeling in fermentation process was decribed in this paper.A production rules representation based on database was presented.The definitions of production rules for biomass soft-sensor hybrid modeling knowledge were proposed.A knowledge base with layered structure was introduced.A breadth-first reasoning approach based on match degree(BFMD) was developed.The definition and calculation method of match degree were illustrated.Compared with the depth-first reasoning approach based on exhaustive method(DFEM),the BFMD needs fewer introduced variables.This expert system could reduce the reasoning steps effectively,and advance reasoning efficiency.Tests shows that reasoning efficiency of the expert system using BFMD in the knowledge base with layered structure is improved 12.9% averagely,compared with using DFEM in the knowledge base with ranking structure.
基金Project(51766007)supported by the National Natural Science Foundation of ChinaProject(U1602272)supported by the NSFC-Yunnan Joint Fund Project+1 种基金Project(2015FB128)supported by the Natural Science Fund Project in Yunnan Province,ChinaProject(CNMRCUTS1704)supported by the Research Fund from State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization,China
文摘Biodiesel is a kind of clean and renewable energy. The effect of ethanol addition on the flame characteristics of waste oil biodiesel is studied by using OH-PLIF technique from the perspective of OH radical evolution. Ethanol addition leads to the appearance of diffusion flame reaction interface ahead of schedule and shortens the diffusion flame height. The experimental results show a linear correlation between the flame height and the fuel flow rate for a given fuel and oxidant. The same conclusion is drawn from the theoretical analysis of the approximate model. In addition. ethanol addition makes the average OH signal intensity of flame at different fuel flow rate tend to be consistent and the fuel flow rate enlarge where the flame field shows the strongest oxidation performance. Average OH signal intensity begins to weaken at larger fuel flow rate, which indicates that fuel flow rate of fuels blended with ethanol can change in larger range and does not significantly affect the uniformity of combustion.
文摘A new generation conical spray system for conventional diesel engines or premixed combustion diesel engines is introduced. By means of oriented impingement method, flexible spray penetration in design is realized. High-speed photograph was used to investigate the spatial distribution characteristics of the new spray for cases of different impingement angles and needle valve opening pressures. The results show that, by applying spray impingement orientation, fuel jets spread along the cone surface as shape of sectors, so the dispersion of jets is increased obviously. Changing on impingement angle leads to variation of penetration, which is critical in homogeneous mixture preparation. Due to the flexibility of spray penetration in design, the spray impingement on liner is avoided in a great extent. The results also indicate that higher needle valve opening pressure results in longer penetration and larger spray angle after impingement. Combustion characteristics of the impinged conical spray were studied in the 1135 type diesel engine. The new impinged conical spray system work smoothly in full load range with better fuel economy and lower emissions of NOx and soot than the original test engine.
文摘Research was undertaken to define the concept of a coach-based braking energy recoupment, storage and regeneration system to augment the acceleration of regional commuter trains hauled by diesel locomotives. Functional specifications were developed having the goal of increasing by 25% the acceleration rate of a train consisting of 10 bi-level coaches hauled by a 3,000 hp diesel locomotive, typical of the rolling stock now in commuter services in Canada and the USA. Examining three alternate hybrid system technologies for train retardation based, respectively, on hydrostatic, battery and ultracapacitor energy storage. The ultracapacitor hybrid system appeared the most promising due to the capability ofultracapacitors to repeatedly and rapidly accept large energy charges without degradation, temperature insensitive and flexible in the placement of modules in the limited space available. Analyses of train operation simulations showed that in addition to augmenting acceleration and reducing trip time, braking energy recoupment reduced fuel consumption and concomitant diesel emissions.
