With the worsening of energy shortage and environmental pollution,energy storage has received much attention in the fields of renewable and sustainable energy in recent years.It is widely known that energy storage is ...With the worsening of energy shortage and environmental pollution,energy storage has received much attention in the fields of renewable and sustainable energy in recent years.It is widely known that energy storage is a technique storing excess energy in one form and converting it back to the same form or another when necessary[1].Especially energy storage occupies an important position in solar energy,wind energy and ocean energy.Generally,energy storage methods include mechanical energy storage,展开更多
As the only controllable means of a micro gas turbine(MGT)combustor during unit operation,pilot fuel ratio(PFR)is the key to achieving stable combustion and low pollutant emission.This paper discusses the influence of...As the only controllable means of a micro gas turbine(MGT)combustor during unit operation,pilot fuel ratio(PFR)is the key to achieving stable combustion and low pollutant emission.This paper discusses the influence of PFR on the inner flow field structure and pollutant emissions.The steady-state three-dimensional RANS method with a 40-step reduced methane-air kinetics mechanism is used to study the reaction flow field and species field with PFR of 9.0%,12.7%,15.2%and 17.6%.Results show that,with the decrease in PFR,the axial velocity and temperature near the central axis of the combustion chamber show a tendency to decrease.A similar separation phenomenon occurred in the core pyrolysis reaction zone(measured by HCO)and oxidation zone(measured by OH),which is more conducive to promoting the oxidation of CO.The quantitative effect of the pilot flame on nitrogen oxides(NO_(x))was separated by using inert gas instead of nitrogen in combustion air.It was found that the NOx produced by the pilot flame under the operation condition with a PFR of 9.0%was 3.2×10^(−6),accounting for 17.4%of the total NOx emission,which was twice that of PFR.展开更多
According to statistics of International Service for the Acquisition of Agri-biotech Applications(ISAAA),18million farmers in 28 countries planted more than 181million hectares of genetically modified(GM)crops in2014,...According to statistics of International Service for the Acquisition of Agri-biotech Applications(ISAAA),18million farmers in 28 countries planted more than 181million hectares of genetically modified(GM)crops in2014,at an annual growth rate of between 3%–4%,with6.3 million ha more than 2013[1].Among these counties,China ranks the sixth with 3.9 million ha.Globally,27kinds of transgenic crops have been approved.The four main food groups for which GM varieties are展开更多
Under the influence of the information technology revolution,the teaching method,as the way to impart teaching content or the means to realize teaching content,has undergone a process of constant evolution and transfo...Under the influence of the information technology revolution,the teaching method,as the way to impart teaching content or the means to realize teaching content,has undergone a process of constant evolution and transformation.This transformation is still ongoing.In order to explain this phenomenon,we establish a three-dimension analysis framework of"ECONOMIC BASE-INFORMATION TECHNOLOGY-CULTURE".All kinds of logics involved in them are closely linked,thus influencing each other.At the same time,these aspects constantly affect the historical trajectory of the evolution.Based on the above analysis framework,the paper uses the historical approach to expound the evolution path on teaching methods in China since ancient times and divides it into four stages.Combined with the practical problems and interview results,we rethink the present information teaching methods.In the end,some suggestions are put forward in order to promote the further development of education-related fields.展开更多
The application of phase-change materials (PCM)for thermal-energy storage is hampered by their low thermal conductivity.Copper particles (CP)and copper foam (CF)were used to enhance the thermal conductivity of a micro...The application of phase-change materials (PCM)for thermal-energy storage is hampered by their low thermal conductivity.Copper particles (CP)and copper foam (CF)were used to enhance the thermal conductivity of a microencapsulated phase-change material (MicroPCM).The effects of the CP size and mass fraction and the pore number per inch (PPI)of the CF on the thermal properties of the MicroPCM were investigated.The chemical and microstructures of the MicroPCM and its CP composites were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy,respectively. Their thermal conductivities,phase-change temperatures,and latent heats were measured.Adding CP into the MicroPCM decreased the latent heats with increasing loadings.The thermal conductivities of MicroPCM/CP (Swt%,50nm diameter)and MicroPCM/CF (PPI 30)were 1.12times and 3.46times that of the unmodified MicroPCM at 20℃,respectively.Thermal-energy storage performances of the MicroPCM/CF composites were studied at a power of 2.9±0.1W.The temperature of the contact surfaces of the pure MicroPCM and its composites (PPI 10,PPI 20,PPI 30)was 75.88,51.27,50.52,and 50.23℃,respectively.The composites displayed more uniform temperature distributions.展开更多
Combustion with lean premixed and low swirl is an effective way of flame organization.It can improve the flame stability and reduce NOX emission.In this kind of combustion,one of the most important issues is fuel/air ...Combustion with lean premixed and low swirl is an effective way of flame organization.It can improve the flame stability and reduce NOX emission.In this kind of combustion,one of the most important issues is fuel/air premixed characteristics.How the structure parameters influence that issue is figured out through numerical simulation.The structure parameters concerned in the study are as follows.They are shape of blades,number of blades,location and shape of gas jet.The influences of them are analysed with comprehensive consideration of many aspects.With the same light shading rate and stagger angle,the axial swirler with curved blades has worse premixed uniformity and lower pressure loss than the one with straight blades.With the same structure of each blade,the decrease of the quantity of blades does influence the pressure loss,while the quantity of gas jets changes correspondingly.But it has little effect on premixed uniformity in a certain range.However,more blades make contribution to better premixed performance.When the total flow area is the same,the axial and circumferential positions of the fuel jets also greatly influence the premixing process.When the fuel jets are upstream the blades and locate at middle of the vanes,the premixing performance is the best.Meanwhile,the jet direction of the fuel jets is a very important influencing factor of the premixing process.When the fuel jet direction is oblique downward at an angle of 30°to the horizontal,the premixing effect is better than the horizontal outflow,which is better than the oblique upward structure.展开更多
A methodology is proposed to handle problem that under equiproble address of packet traffic at the input port, Generalized Shuffle-Exchange Network (GSEN) routes traffic unevenly because of the unbalanced routing tags...A methodology is proposed to handle problem that under equiproble address of packet traffic at the input port, Generalized Shuffle-Exchange Network (GSEN) routes traffic unevenly because of the unbalanced routing tags. The idea is to use routing tag according to probability, which can be evaluated by using Moore-Penrose inverse in matrix analysis. An instance is used to illustrate the idea, and the simulation is done to show the improvement in performance issues.展开更多
J. L Lions and W. A. Stranss [1] have proved the existence of a global solution of the initial boundary value problem for nonlinear generalized Euler-Possion-Darboux equation. In this paper we are going to investigate...J. L Lions and W. A. Stranss [1] have proved the existence of a global solution of the initial boundary value problem for nonlinear generalized Euler-Possion-Darboux equation. In this paper we are going to investigate the asymptotic behavior of the global solution by a difference inequality.展开更多
The precursore Zn（en）2S （en=ethylenediamine） were prepared via a solvothermal process from elemental sulfur and zinc using ethylenediamine as a solvent. Detailed characterizations of the infrared （IR） absorption...The precursore Zn（en）2S （en=ethylenediamine） were prepared via a solvothermal process from elemental sulfur and zinc using ethylenediamine as a solvent. Detailed characterizations of the infrared （IR） absorption spectrum, powder X-ray diffraction （XRD） and thermogravimetric analysis （TG） confirmed two en coordinated with Zn2+ to form a complex cation. The morphological property was also characterized by transmission electron microscopy （TEM ） and electron diffraction analysis （ED）. Phase-pure hexagonal wurtzite ZnS products were obtained by annealing the precursor in nitrogen stream at about 900 ℃. Zn（en）2S showed a nanosize of about 30 nm, and ZnS of about 60 nm. The fluorescence spectra were also studied. PL results showed that Zn（en）2S excited a fluorescence at 452 nm.展开更多
Nanosize CdS semiconductor particles were synthesized using the solvothermal technique. The structure was characterized by means of XRD,TEM and ED techniques. PANI film was prepared by electro-chemistry method onto th...Nanosize CdS semiconductor particles were synthesized using the solvothermal technique. The structure was characterized by means of XRD,TEM and ED techniques. PANI film was prepared by electro-chemistry method onto the indium-tin oxide glass. The nanoparticles were doped on PANI film by the dipping process, and the self-assembled nanoparticles-PANI composite film was acquired. The photoelectric properties of the self-assembled film were studied by PL and Z-scan method.展开更多
基于厘米级高分辨率无人机影像,应用面向对象方法(Object-Based Image Analysis,OBIA)对吉林省伊通县椽子沟流域的横坡改垄、地埂植物带、生态恢复乔木林、生态恢复草地等水土保持措施进行自动精准识别。应用超绿指数(Excess Green Inde...基于厘米级高分辨率无人机影像,应用面向对象方法(Object-Based Image Analysis,OBIA)对吉林省伊通县椽子沟流域的横坡改垄、地埂植物带、生态恢复乔木林、生态恢复草地等水土保持措施进行自动精准识别。应用超绿指数(Excess Green Index,ExG)、超红指数(Excess Red Index,ExR)、归一化差异指数(Normalized Difference Index,NDI)等光谱指数,形状的主方向、形状指数等形状特征,均值(Mean)、方差(Variance)、对比度(Contrast)等纹理特征进行措施的特征提取。结果表明:研究区水土保持措施识别的总体精度可达91.24%,Kappa系数为0.87;对垄台、垄沟等线性水土保持措施总体精度可达72.33%,Kappa系数为0.63。基于厘米级无人机影像,应用面向对象方法基本可实现对黑土区水土保持措施的精准识别,也可对垄台垄沟等线性措施进行自动识别,研究结果可为水土保持措施实施范围及完好程度的动态监测提供参考依据。展开更多
基金supported by the National Natural Science Foundation of China (No. U1407125)the Key Disciplines Fund of China University of Mining and Technology (No. XZD201601)
文摘With the worsening of energy shortage and environmental pollution,energy storage has received much attention in the fields of renewable and sustainable energy in recent years.It is widely known that energy storage is a technique storing excess energy in one form and converting it back to the same form or another when necessary[1].Especially energy storage occupies an important position in solar energy,wind energy and ocean energy.Generally,energy storage methods include mechanical energy storage,
基金supported by the Science and Technology Commission of Shanghai Municipality(20dz1204902).
文摘As the only controllable means of a micro gas turbine(MGT)combustor during unit operation,pilot fuel ratio(PFR)is the key to achieving stable combustion and low pollutant emission.This paper discusses the influence of PFR on the inner flow field structure and pollutant emissions.The steady-state three-dimensional RANS method with a 40-step reduced methane-air kinetics mechanism is used to study the reaction flow field and species field with PFR of 9.0%,12.7%,15.2%and 17.6%.Results show that,with the decrease in PFR,the axial velocity and temperature near the central axis of the combustion chamber show a tendency to decrease.A similar separation phenomenon occurred in the core pyrolysis reaction zone(measured by HCO)and oxidation zone(measured by OH),which is more conducive to promoting the oxidation of CO.The quantitative effect of the pilot flame on nitrogen oxides(NO_(x))was separated by using inert gas instead of nitrogen in combustion air.It was found that the NOx produced by the pilot flame under the operation condition with a PFR of 9.0%was 3.2×10^(−6),accounting for 17.4%of the total NOx emission,which was twice that of PFR.
文摘According to statistics of International Service for the Acquisition of Agri-biotech Applications(ISAAA),18million farmers in 28 countries planted more than 181million hectares of genetically modified(GM)crops in2014,at an annual growth rate of between 3%–4%,with6.3 million ha more than 2013[1].Among these counties,China ranks the sixth with 3.9 million ha.Globally,27kinds of transgenic crops have been approved.The four main food groups for which GM varieties are
文摘Under the influence of the information technology revolution,the teaching method,as the way to impart teaching content or the means to realize teaching content,has undergone a process of constant evolution and transformation.This transformation is still ongoing.In order to explain this phenomenon,we establish a three-dimension analysis framework of"ECONOMIC BASE-INFORMATION TECHNOLOGY-CULTURE".All kinds of logics involved in them are closely linked,thus influencing each other.At the same time,these aspects constantly affect the historical trajectory of the evolution.Based on the above analysis framework,the paper uses the historical approach to expound the evolution path on teaching methods in China since ancient times and divides it into four stages.Combined with the practical problems and interview results,we rethink the present information teaching methods.In the end,some suggestions are put forward in order to promote the further development of education-related fields.
基金National Natural Science Foundation of China (Grant No.U1407125),the Qing Lan Project of Jiangsu Province,the 333High Level Talents Training Project of Jiangsu Province,and the Six Talent Peak High-level Talent Project of Jiangsu Province,China.
文摘The application of phase-change materials (PCM)for thermal-energy storage is hampered by their low thermal conductivity.Copper particles (CP)and copper foam (CF)were used to enhance the thermal conductivity of a microencapsulated phase-change material (MicroPCM).The effects of the CP size and mass fraction and the pore number per inch (PPI)of the CF on the thermal properties of the MicroPCM were investigated.The chemical and microstructures of the MicroPCM and its CP composites were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy,respectively. Their thermal conductivities,phase-change temperatures,and latent heats were measured.Adding CP into the MicroPCM decreased the latent heats with increasing loadings.The thermal conductivities of MicroPCM/CP (Swt%,50nm diameter)and MicroPCM/CF (PPI 30)were 1.12times and 3.46times that of the unmodified MicroPCM at 20℃,respectively.Thermal-energy storage performances of the MicroPCM/CF composites were studied at a power of 2.9±0.1W.The temperature of the contact surfaces of the pure MicroPCM and its composites (PPI 10,PPI 20,PPI 30)was 75.88,51.27,50.52,and 50.23℃,respectively.The composites displayed more uniform temperature distributions.
基金This study is supported by Shanghai Committee of Science and Technology(Grant No.18DZ1202003).
文摘Combustion with lean premixed and low swirl is an effective way of flame organization.It can improve the flame stability and reduce NOX emission.In this kind of combustion,one of the most important issues is fuel/air premixed characteristics.How the structure parameters influence that issue is figured out through numerical simulation.The structure parameters concerned in the study are as follows.They are shape of blades,number of blades,location and shape of gas jet.The influences of them are analysed with comprehensive consideration of many aspects.With the same light shading rate and stagger angle,the axial swirler with curved blades has worse premixed uniformity and lower pressure loss than the one with straight blades.With the same structure of each blade,the decrease of the quantity of blades does influence the pressure loss,while the quantity of gas jets changes correspondingly.But it has little effect on premixed uniformity in a certain range.However,more blades make contribution to better premixed performance.When the total flow area is the same,the axial and circumferential positions of the fuel jets also greatly influence the premixing process.When the fuel jets are upstream the blades and locate at middle of the vanes,the premixing performance is the best.Meanwhile,the jet direction of the fuel jets is a very important influencing factor of the premixing process.When the fuel jet direction is oblique downward at an angle of 30°to the horizontal,the premixing effect is better than the horizontal outflow,which is better than the oblique upward structure.
基金Supported by the National High-Tech Programs(No.2002AA103062, No.2002AA121061 and No.2003AA103520) the Huawei Technologies Co. under contract number YBCN2002001.
文摘A methodology is proposed to handle problem that under equiproble address of packet traffic at the input port, Generalized Shuffle-Exchange Network (GSEN) routes traffic unevenly because of the unbalanced routing tags. The idea is to use routing tag according to probability, which can be evaluated by using Moore-Penrose inverse in matrix analysis. An instance is used to illustrate the idea, and the simulation is done to show the improvement in performance issues.
文摘J. L Lions and W. A. Stranss [1] have proved the existence of a global solution of the initial boundary value problem for nonlinear generalized Euler-Possion-Darboux equation. In this paper we are going to investigate the asymptotic behavior of the global solution by a difference inequality.
文摘The precursore Zn（en）2S （en=ethylenediamine） were prepared via a solvothermal process from elemental sulfur and zinc using ethylenediamine as a solvent. Detailed characterizations of the infrared （IR） absorption spectrum, powder X-ray diffraction （XRD） and thermogravimetric analysis （TG） confirmed two en coordinated with Zn2+ to form a complex cation. The morphological property was also characterized by transmission electron microscopy （TEM ） and electron diffraction analysis （ED）. Phase-pure hexagonal wurtzite ZnS products were obtained by annealing the precursor in nitrogen stream at about 900 ℃. Zn（en）2S showed a nanosize of about 30 nm, and ZnS of about 60 nm. The fluorescence spectra were also studied. PL results showed that Zn（en）2S excited a fluorescence at 452 nm.
文摘Nanosize CdS semiconductor particles were synthesized using the solvothermal technique. The structure was characterized by means of XRD,TEM and ED techniques. PANI film was prepared by electro-chemistry method onto the indium-tin oxide glass. The nanoparticles were doped on PANI film by the dipping process, and the self-assembled nanoparticles-PANI composite film was acquired. The photoelectric properties of the self-assembled film were studied by PL and Z-scan method.
文摘基于厘米级高分辨率无人机影像,应用面向对象方法(Object-Based Image Analysis,OBIA)对吉林省伊通县椽子沟流域的横坡改垄、地埂植物带、生态恢复乔木林、生态恢复草地等水土保持措施进行自动精准识别。应用超绿指数(Excess Green Index,ExG)、超红指数(Excess Red Index,ExR)、归一化差异指数(Normalized Difference Index,NDI)等光谱指数,形状的主方向、形状指数等形状特征,均值(Mean)、方差(Variance)、对比度(Contrast)等纹理特征进行措施的特征提取。结果表明:研究区水土保持措施识别的总体精度可达91.24%,Kappa系数为0.87;对垄台、垄沟等线性水土保持措施总体精度可达72.33%,Kappa系数为0.63。基于厘米级无人机影像,应用面向对象方法基本可实现对黑土区水土保持措施的精准识别,也可对垄台垄沟等线性措施进行自动识别,研究结果可为水土保持措施实施范围及完好程度的动态监测提供参考依据。
