In order to address typical problems due to the huge demand of oil for consumption in traditional internal combustion engines,a new more efficient combustion mode is proposed and studied in the framework of Computatio...In order to address typical problems due to the huge demand of oil for consumption in traditional internal combustion engines,a new more efficient combustion mode is proposed and studied in the framework of Computational Fluid Dynamics(CFD).Moreover,a Non-dominated Sorting Genetic Algorithm(NSGA-Ⅱ)is applied to optimize the related parameters,namely,the engine methanol ratio,the fuel injection time,the initial temperature,the Exhaust Gas Re-Circulation(EGR)rate,and the initial pressure.The so-called Conventional Diesel Combustion(CDC),Homogeneous Charge Compression Ignition(HCCI)and the Reactivity Controlled Compression Ignition(RCCI)combustion modes are compared.The results show that RCCI has a higher methanol ratio and an earlier injection timing with moderate EGR rate and higher initial pressure.The initial temperature increases as the methanol ratio increases.In comparison,CDC has the lowest hydrocarbon and CO emissions and the highest combustion efficiency.At different crankshaft rotation angles corresponding to 50%of the combustion amount(CA50),the combustion temperature and boundary layer temperature of HCCI change significantly,while those of RCCI undergo limited variations.At the same CA50,the exergy losses of HCCI and RCCI are lower than that of the CDC.On the basis of these findings,it can be concluded that the methanol/diesel RCCI engine can be used to obtain a clean and efficient combustion process,which should be regarded as a promising combustion mode.展开更多
We present an efficient three-dimensional coupled-mode model based on the Fourier synthesis technique. In principle, this model is a one-way model, and hence provides satisfactory accuracy for problems where the forwa...We present an efficient three-dimensional coupled-mode model based on the Fourier synthesis technique. In principle, this model is a one-way model, and hence provides satisfactory accuracy for problems where the forward scattering dominates. At the same time, this model provides an efficiency gain of an order of magnitude or more over two-way coupled-mode models. This model can be applied to three-dimensional range-dependent problems with a slowly varying bathymetry or internal waves. A numerical example of the latter is demonstrated in this work. Comparisons of both accuracy and efficiency between the present model and a benchmark model are also provided.展开更多
To investigate the effects of different vegetable growing regions and planting modes on soil quality,soils in high,medium and low altitude areas of Guizhou were respectively sampled under different vegetable efficient...To investigate the effects of different vegetable growing regions and planting modes on soil quality,soils in high,medium and low altitude areas of Guizhou were respectively sampled under different vegetable efficient planting modes,and the variations of soil microbial flora and enzyme activities were analyzed. The soil microbial count and total bacteria of the vegetable efficient cultivation mode were significantly higher than that of the control （traditional planting mode） in each planting area,and the microbial diversity index was also improved to varying de- grees.The soil phosphatase,catalase and urease activities of the vegetable efficient planting mode were higher than that of the control.The soil catalase and urease activities were higher than that of the control by 1.37-1.44 and 1.51-2.80 times. Application of vegetable efficient planting mode in different regions will help to im- prove the soil quality in a given period.展开更多
Transportation accounts for 80% of open-cut coal mine carbon emissions. With regard to the energy con- sumption and carbon emissions of transportation within an open-cut mine, this paper systematically compared the wo...Transportation accounts for 80% of open-cut coal mine carbon emissions. With regard to the energy con- sumption and carbon emissions of transportation within an open-cut mine, this paper systematically compared the work and energy consumption of a truck and belt conveyor on a theoretical basis, and con- structed a model to calculate the energy consumption of open-cut mine transportation. Life cycle carbon emission factors and power consumption calculation model were established through a Process Analysis- Life Cycle Analysis （PA-LCA）. The following results were obtained： （1） the energy consumption of truck transportation was four to twelve times higher than that of the belt conveyor; （2） the C02 emissions from truck transportation were three to ten times higher than those of the belt conveyor; （3） with the increase in the slope angle for transportation, the ratio of truck to belt conveyor for both energy consumption and carbon emissions gradually decreased; （4） based on 2013 prices in China, the energy cost of transportation using a belt conveyor in open-cut coal mines could save 0.6-2.4 Yuan/（t kin） compared to truck transportation.展开更多
With the basic characteristics of conventional horizontal wells,the so-called complex wells including horizontal extended-reach wells,multi-lateral horizontal wells,U-shaped wells,cluster horizontal wells,etc.,are adv...With the basic characteristics of conventional horizontal wells,the so-called complex wells including horizontal extended-reach wells,multi-lateral horizontal wells,U-shaped wells,cluster horizontal wells,etc.,are advanced well types for the efficient development of low-permeability,unconventional,deep-water,and deep oil and gas reservoirs,which have been highly concerned all over the world.Significant progress at home and abroad has been made in relevant researches and practices and is expected to play an important role in the efficient development of shale oil and gas.To meet the basic needs of environment&safety,land conservation,cost reducing and efficiency improving,it is urgent to create a unique and efficient mode for developing shale gas.Therefore,an efficient shale gas development mode for mountainous areas and an engineering and technical support system are presented based on large cluster horizontal-well engineering.An equation is thus obtained for calculating the maximum number of horizontal wells arranged allowably in“Well Factory”on a single platform.The general research and development of large extended-reach well technology are analyzed by expounding the basic concept of an extended-reach well and its drilling extension limit.And a calculation method is thus established to predict the maximum measured depth of open hole in extended-reach drilling.Moreover,some relevant research results and their significance for downhole tubular mechanics&mechanical extension limits in extended-reach drilling are also briefly introduced in this paper.The conclusions are drawn that,by following the idea of“integration of geology and engineering”in oil and gas development,these research results have a foreseeable application prospect in shale gas development in the mountainous areas in the future,and will contribute to new progress in China's“Shale Revolution”.展开更多
It is shown that orbital angular momentum(OAM) is a promising new resource in future classical and quantum communications. However, the separation of OAM modes is still a big challenge. In this paper, we propose a sim...It is shown that orbital angular momentum(OAM) is a promising new resource in future classical and quantum communications. However, the separation of OAM modes is still a big challenge. In this paper, we propose a simple and efficient separation method with a radial varying phase. In the method, specific radial varying phases are designed and modulated for different OAM modes. The resultant beam is focused to the spots with different horizontal and vertical positions after a convex lens, when the coordinate transformation, including two optical elements with coordinate transformation phase and correct phase, operates on the received beam.The horizontal position of the spot is determined by the vortex phases, and the vertical position of the spot is dependent on the radial varying phases. The simulation and experimental results show that the proposed method is feasible both for separation of two OAM modes and separation of three OAM modes. The proposed separation method is available in principle for any neighboring OAM modes because the radial varying phase is controlled. Additionally, no extra instruments are introduced, and there is no diffraction and narrowing process limitation for the separation.展开更多
In this paper we consider data transmission in a decode-and-forward(DF)relay-assisted network in which the relay is energy harvesting(EH) powered while the base station(BS) is power-grid powered.Our purpose is to maxi...In this paper we consider data transmission in a decode-and-forward(DF)relay-assisted network in which the relay is energy harvesting(EH) powered while the base station(BS) is power-grid powered.Our purpose is to maximize the BS's energy efficiency(EE) while making full use of the relay's renewable energy and satisfying the specific average throughput requirements.In contrast to existing literature on energy harvesting system which only considers the radio transmission power,we take the static circuit power into account as well.We formulate the EE optimization problem and prove that the EE of the BS and relay are both quasiconvex in the instantaneous transmission rate.Then we divide the complex optimization problem into two point-to-point link level optimization parts and propose an energyefficient resource allocation(EERA) scheme in which power control and sleep mode management are jointly used.The simulation results demonstrate that EERA may achieve good energy saving effects.We also compare the EE of an energy harvesting relay system with a power-grid powered one and provide more insight into the EE problem of energy harvesting relay system.展开更多
By studying the cultural background and corporate culture in China, Japan and USA, this paper analyzes the effects of cultural background and corporation culture on the transaction cost and the efficiency of control r...By studying the cultural background and corporate culture in China, Japan and USA, this paper analyzes the effects of cultural background and corporation culture on the transaction cost and the efficiency of control right, thus shows that cultural backgrounds have great impact on merger. This paper further studies the choice and application of the mode of culture combination of the transnational merger.展开更多
Space division multiplexing(SDM)can achieve higher communication transmission capacity by exploiting more spatial channels in a single optical fiber.For weakly coupled few-mode fiber,different mode groups(MGs)are high...Space division multiplexing(SDM)can achieve higher communication transmission capacity by exploiting more spatial channels in a single optical fiber.For weakly coupled few-mode fiber,different mode groups(MGs)are highly isolated from each other,so the SDM system can be simplified by utilizing MG multiplexing and intensity modulation direct detection.A key issue to be addressed here is MG demultiplexing,which requires processing all the modes within a single MG in contrast to MG multiplexing.Benefiting from the great light manipulation freedom of the diffractive optical network(DON),we achieve efficient separation of the MGs and receive them with the multimode fiber(MMF)array.To fully exploit the mode field freedom of the MMF,a non-deterministic mode conversion strategy is proposed here to optimize the DON,which enables high-efficiency demultiplexing with a much smaller number of phase plates.As a validation,we design a 6-MG demultiplexer consisting of only five phase plates;each MG is constituted by several orbital angular momentum modes.The designed average loss and crosstalk at the wavelength of 1550 nm are 0.5 dB and-25 dB,respectively.In the experiment,the loss after coupling to the MMF ranged from 4.1 to 4.9 dB,with an average of 4.5 dB.The inter-MG crosstalk is better than-12 dB,with an average of-18 dB.These results well support the proposed scheme and will provide a practical solution to the MG demultiplexing problem in a short-distance SDM system.展开更多
Invert traps are used to trap sewer solids flowing into a sewer drainage system, The performance of the invert trap in an open rectangular channel was experimentally and numerically analysed using field sewer solids c...Invert traps are used to trap sewer solids flowing into a sewer drainage system, The performance of the invert trap in an open rectangular channel was experimentally and numerically analysed using field sewer solids collected from a sewer drain. Experiments showed that the free water surface rises over the central opening （slot） of the invert trap, which reduces the velocity near the slot and allows more sediment to be trapped in comparison with the case for the fixed-lid model （assuming closed conduit flow with a shear-free top wall） used by earlier investigators. This phenomenon cannot be modelled using a closed conduit model as no extra space is provided for the fluctuation of the water surface, whereas this space is provided in the volume of fluid （VOF） model in the form of air space in ANSYS Fluent 14.0 software. Additionally, the zero atmospheric pressure at the free water surface cannot be modelled in a fixed-lid model. In the present study, experimental trap efflciencies of the invert trap using field sewer solids were fairly validated using a three-dimensional computational fluid dynamics model （VOF model） coupled with a stochastic discrete phase model. The flow field （i.e., velocities） predicted by the VOF model were compared with experimental velocities obtained employing particle image velocimetry. The water surface profile above the invert trap predicted by the VOF model was found to be in good agreement with the experimentally measured profile. The present study thus showed that the VOF model can be used with the stochastic discrete phase model to well predict the performance of invert traps.展开更多
文摘In order to address typical problems due to the huge demand of oil for consumption in traditional internal combustion engines,a new more efficient combustion mode is proposed and studied in the framework of Computational Fluid Dynamics(CFD).Moreover,a Non-dominated Sorting Genetic Algorithm(NSGA-Ⅱ)is applied to optimize the related parameters,namely,the engine methanol ratio,the fuel injection time,the initial temperature,the Exhaust Gas Re-Circulation(EGR)rate,and the initial pressure.The so-called Conventional Diesel Combustion(CDC),Homogeneous Charge Compression Ignition(HCCI)and the Reactivity Controlled Compression Ignition(RCCI)combustion modes are compared.The results show that RCCI has a higher methanol ratio and an earlier injection timing with moderate EGR rate and higher initial pressure.The initial temperature increases as the methanol ratio increases.In comparison,CDC has the lowest hydrocarbon and CO emissions and the highest combustion efficiency.At different crankshaft rotation angles corresponding to 50%of the combustion amount(CA50),the combustion temperature and boundary layer temperature of HCCI change significantly,while those of RCCI undergo limited variations.At the same CA50,the exergy losses of HCCI and RCCI are lower than that of the CDC.On the basis of these findings,it can be concluded that the methanol/diesel RCCI engine can be used to obtain a clean and efficient combustion process,which should be regarded as a promising combustion mode.
基金Supported by the National Natural Science Foundation of China under Grant No 11774374the Natural Science Foundation of Shandong Province of China under Grant No ZR2016AL10
文摘We present an efficient three-dimensional coupled-mode model based on the Fourier synthesis technique. In principle, this model is a one-way model, and hence provides satisfactory accuracy for problems where the forward scattering dominates. At the same time, this model provides an efficiency gain of an order of magnitude or more over two-way coupled-mode models. This model can be applied to three-dimensional range-dependent problems with a slowly varying bathymetry or internal waves. A numerical example of the latter is demonstrated in this work. Comparisons of both accuracy and efficiency between the present model and a benchmark model are also provided.
基金Supported by Key Project from National Spark Plan,China(2012GA820001)Special Project of Guizhou Provincial Science and Technology,China[Qiankehe Special Project(2011)6001)]+1 种基金"321"Efficient Planting Technique Integration and Demonstration of Vegetable from Technology Ombudsman,China[(2013)6061-1)]Guizhou Vegetable Industry Technique System Construction Program,China(GZCYTX2011-0101)~~
文摘To investigate the effects of different vegetable growing regions and planting modes on soil quality,soils in high,medium and low altitude areas of Guizhou were respectively sampled under different vegetable efficient planting modes,and the variations of soil microbial flora and enzyme activities were analyzed. The soil microbial count and total bacteria of the vegetable efficient cultivation mode were significantly higher than that of the control （traditional planting mode） in each planting area,and the microbial diversity index was also improved to varying de- grees.The soil phosphatase,catalase and urease activities of the vegetable efficient planting mode were higher than that of the control.The soil catalase and urease activities were higher than that of the control by 1.37-1.44 and 1.51-2.80 times. Application of vegetable efficient planting mode in different regions will help to im- prove the soil quality in a given period.
基金supported by the key project of the National Natural Science Foundation of China(No.51034005)the Research Fund for the Doctoral Program of Higher Education(the Specialized Research Fund for the Doctoral Program of Higher Education of China)(No.20100095110019)+1 种基金the National‘‘Twelfth Five-Year’’Plan for Science&Technology Support(No.2014BAC14B00)the National High Technology Research and Development Program of China(No.2012AA062004)
文摘Transportation accounts for 80% of open-cut coal mine carbon emissions. With regard to the energy con- sumption and carbon emissions of transportation within an open-cut mine, this paper systematically compared the work and energy consumption of a truck and belt conveyor on a theoretical basis, and con- structed a model to calculate the energy consumption of open-cut mine transportation. Life cycle carbon emission factors and power consumption calculation model were established through a Process Analysis- Life Cycle Analysis （PA-LCA）. The following results were obtained： （1） the energy consumption of truck transportation was four to twelve times higher than that of the belt conveyor; （2） the C02 emissions from truck transportation were three to ten times higher than those of the belt conveyor; （3） with the increase in the slope angle for transportation, the ratio of truck to belt conveyor for both energy consumption and carbon emissions gradually decreased; （4） based on 2013 prices in China, the energy cost of transportation using a belt conveyor in open-cut coal mines could save 0.6-2.4 Yuan/（t kin） compared to truck transportation.
基金supported by National Natural Science Foundation of China(Grant numbers:51821092 and U1762214)。
文摘With the basic characteristics of conventional horizontal wells,the so-called complex wells including horizontal extended-reach wells,multi-lateral horizontal wells,U-shaped wells,cluster horizontal wells,etc.,are advanced well types for the efficient development of low-permeability,unconventional,deep-water,and deep oil and gas reservoirs,which have been highly concerned all over the world.Significant progress at home and abroad has been made in relevant researches and practices and is expected to play an important role in the efficient development of shale oil and gas.To meet the basic needs of environment&safety,land conservation,cost reducing and efficiency improving,it is urgent to create a unique and efficient mode for developing shale gas.Therefore,an efficient shale gas development mode for mountainous areas and an engineering and technical support system are presented based on large cluster horizontal-well engineering.An equation is thus obtained for calculating the maximum number of horizontal wells arranged allowably in“Well Factory”on a single platform.The general research and development of large extended-reach well technology are analyzed by expounding the basic concept of an extended-reach well and its drilling extension limit.And a calculation method is thus established to predict the maximum measured depth of open hole in extended-reach drilling.Moreover,some relevant research results and their significance for downhole tubular mechanics&mechanical extension limits in extended-reach drilling are also briefly introduced in this paper.The conclusions are drawn that,by following the idea of“integration of geology and engineering”in oil and gas development,these research results have a foreseeable application prospect in shale gas development in the mountainous areas in the future,and will contribute to new progress in China's“Shale Revolution”.
基金National Natural Science Foundation of China(NSFC)(61475075,61271238)Open Research Fund of Key Lab of Broadband Wireless Communication and Sensor Network Technology,Ministry of Education of the People's Republic of China(MOE)(NYKL2015011)
文摘It is shown that orbital angular momentum(OAM) is a promising new resource in future classical and quantum communications. However, the separation of OAM modes is still a big challenge. In this paper, we propose a simple and efficient separation method with a radial varying phase. In the method, specific radial varying phases are designed and modulated for different OAM modes. The resultant beam is focused to the spots with different horizontal and vertical positions after a convex lens, when the coordinate transformation, including two optical elements with coordinate transformation phase and correct phase, operates on the received beam.The horizontal position of the spot is determined by the vortex phases, and the vertical position of the spot is dependent on the radial varying phases. The simulation and experimental results show that the proposed method is feasible both for separation of two OAM modes and separation of three OAM modes. The proposed separation method is available in principle for any neighboring OAM modes because the radial varying phase is controlled. Additionally, no extra instruments are introduced, and there is no diffraction and narrowing process limitation for the separation.
基金supported by National programs for High Technology Research and Development(2012AA011402)National Basic Research Program of China(2012CB316002)National Nature Science Foundation of China(61172088)
文摘In this paper we consider data transmission in a decode-and-forward(DF)relay-assisted network in which the relay is energy harvesting(EH) powered while the base station(BS) is power-grid powered.Our purpose is to maximize the BS's energy efficiency(EE) while making full use of the relay's renewable energy and satisfying the specific average throughput requirements.In contrast to existing literature on energy harvesting system which only considers the radio transmission power,we take the static circuit power into account as well.We formulate the EE optimization problem and prove that the EE of the BS and relay are both quasiconvex in the instantaneous transmission rate.Then we divide the complex optimization problem into two point-to-point link level optimization parts and propose an energyefficient resource allocation(EERA) scheme in which power control and sleep mode management are jointly used.The simulation results demonstrate that EERA may achieve good energy saving effects.We also compare the EE of an energy harvesting relay system with a power-grid powered one and provide more insight into the EE problem of energy harvesting relay system.
文摘By studying the cultural background and corporate culture in China, Japan and USA, this paper analyzes the effects of cultural background and corporation culture on the transaction cost and the efficiency of control right, thus shows that cultural backgrounds have great impact on merger. This paper further studies the choice and application of the mode of culture combination of the transnational merger.
基金Guangdong ST Programme(2024B0101030001)National Key Research and Development Program of China(2019YFA0706300,2024YFB2908100)+2 种基金National Natural Science Foundation of China(U22B2010,62035018,U2001601,62227819)The Program of Marine Economy Development Special Fund(Six Marine Industries)under Department of Natural Resources of Guangdong Province(GDNRC[2024]16)Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(SML2023SP231)。
文摘Space division multiplexing(SDM)can achieve higher communication transmission capacity by exploiting more spatial channels in a single optical fiber.For weakly coupled few-mode fiber,different mode groups(MGs)are highly isolated from each other,so the SDM system can be simplified by utilizing MG multiplexing and intensity modulation direct detection.A key issue to be addressed here is MG demultiplexing,which requires processing all the modes within a single MG in contrast to MG multiplexing.Benefiting from the great light manipulation freedom of the diffractive optical network(DON),we achieve efficient separation of the MGs and receive them with the multimode fiber(MMF)array.To fully exploit the mode field freedom of the MMF,a non-deterministic mode conversion strategy is proposed here to optimize the DON,which enables high-efficiency demultiplexing with a much smaller number of phase plates.As a validation,we design a 6-MG demultiplexer consisting of only five phase plates;each MG is constituted by several orbital angular momentum modes.The designed average loss and crosstalk at the wavelength of 1550 nm are 0.5 dB and-25 dB,respectively.In the experiment,the loss after coupling to the MMF ranged from 4.1 to 4.9 dB,with an average of 4.5 dB.The inter-MG crosstalk is better than-12 dB,with an average of-18 dB.These results well support the proposed scheme and will provide a practical solution to the MG demultiplexing problem in a short-distance SDM system.
文摘Invert traps are used to trap sewer solids flowing into a sewer drainage system, The performance of the invert trap in an open rectangular channel was experimentally and numerically analysed using field sewer solids collected from a sewer drain. Experiments showed that the free water surface rises over the central opening （slot） of the invert trap, which reduces the velocity near the slot and allows more sediment to be trapped in comparison with the case for the fixed-lid model （assuming closed conduit flow with a shear-free top wall） used by earlier investigators. This phenomenon cannot be modelled using a closed conduit model as no extra space is provided for the fluctuation of the water surface, whereas this space is provided in the volume of fluid （VOF） model in the form of air space in ANSYS Fluent 14.0 software. Additionally, the zero atmospheric pressure at the free water surface cannot be modelled in a fixed-lid model. In the present study, experimental trap efflciencies of the invert trap using field sewer solids were fairly validated using a three-dimensional computational fluid dynamics model （VOF model） coupled with a stochastic discrete phase model. The flow field （i.e., velocities） predicted by the VOF model were compared with experimental velocities obtained employing particle image velocimetry. The water surface profile above the invert trap predicted by the VOF model was found to be in good agreement with the experimentally measured profile. The present study thus showed that the VOF model can be used with the stochastic discrete phase model to well predict the performance of invert traps.
