When artificial waterfalls are built in gardens,leaves from trees or vegetation often fall into the water storage pool and block the pipelines,requiring regular cleaning of pipelines.This not only increases the manpow...When artificial waterfalls are built in gardens,leaves from trees or vegetation often fall into the water storage pool and block the pipelines,requiring regular cleaning of pipelines.This not only increases the manpower needed for maintenance but also disrupts the use of the waterfalls.Therefore,it is necessary to design a new type of artificial waterfall that is suitable for gardens.The waterfall should incorporate features that make cleaning easier,including filter plates and water funnels to prevent clogging caused by fallen leaves and debris.展开更多
The study explores how educational digitalization enables the precise development of ideological and political education in colleges and universities.Digital transformation enables colleges and universities to accurat...The study explores how educational digitalization enables the precise development of ideological and political education in colleges and universities.Digital transformation enables colleges and universities to accurately define educational objectives,content strategies,effect evaluation,and process management,and realize the precision and intelligence of ideological and political education.The application of big data technology enhances the data-oriented thinking of teachers and students,promotes the accurate application of data,and improves the efficiency of ideological and political education.The research also prospected a new vision of the digital construction of ideological and political courses and clarified the theoretical and practical path of the implementation and evaluation mode of ideological and political courses under digital empowerment.Education digitalization enables precise ideological and political education,which is a key way to promote the innovative development of ideological and political education in colleges and universities and will strongly support the improvement of the overall quality of higher education and the training of excellent talents.展开更多
Internet of Things(IoT)technology is widely used in various fields,and its application in elderly care services has been highlighted in recent years.This study aims to explore how IoT technology can improve the effici...Internet of Things(IoT)technology is widely used in various fields,and its application in elderly care services has been highlighted in recent years.This study aims to explore how IoT technology can improve the efficiency of group-based elderly care services.The concept,characteristics,and current application status of IoT technology in elderly care services were introduced.Secondly,the characteristics and needs of group elderly care services were analyzed,including advantages and challenges,as well as the expectations and needs of the elderly for elderly care services.The evaluation methods and future development directions of IoT technology in improving the efficiency of group elderly care services were discussed,including data collection and analysis methods,selection and measurement of efficiency evaluation indicators,challenges,and development directions.展开更多
A two⁃port encapsulated low⁃contrast grating with suppressed zeroth order under normal incidence is described in this paper.Based on such grating configuration,the improved efficiency and spectral bandwidth of the fir...A two⁃port encapsulated low⁃contrast grating with suppressed zeroth order under normal incidence is described in this paper.Based on such grating configuration,the improved efficiency and spectral bandwidth of the first order for TE and TM polarizations with a designed period of 1860 nm can be obtained.On the one hand,some of the accurate grating parameters were numerically optimized utilizing a rigorous coupled⁃wave analysis;on the other hand,the inherent physical mechanism suppressing the zeroth order through an encapsulated fused⁃silica grating was adequately interpreted on account of a simplified modal method.Encapsulated grating with a cover layer cannot be simply considered as adding a coating on it.Compared with reported surface⁃relief grating,all parameters of encapsulated grating should be re⁃optimized and the optimized performances of encapsulated grating were greatly improved.Therefore,the encapsulated grating can be potentially applied in writing fiber Bragg gratings.展开更多
The article describes the possibilities of application of simulation modeling for the analysis of infrastructure and technology of transport services of enterprises. The main technological and possible economic effect...The article describes the possibilities of application of simulation modeling for the analysis of infrastructure and technology of transport services of enterprises. The main technological and possible economic effects for the enterprises arising at performance of modeling of a transport component of their work are resulted.展开更多
According to the technical approach of green production and yield increase pattern,green,pollution-free,quality and efficiency improvement can be achieved by reducing nitrogen,controlling phosphorus and stabilizing po...According to the technical approach of green production and yield increase pattern,green,pollution-free,quality and efficiency improvement can be achieved by reducing nitrogen,controlling phosphorus and stabilizing potassium,replenishing sulfur,zinc,iron,manganese and boron from the aspects of controlling fertilizer,drug and water.The main measures include combination use of organic and inorganic fertilizer,effective control of the amount of nitrogen and phosphate fertilizer,reduction of the application amount of chemical fertilizers and pesticides,and rational crop rotation to reduce the occurrence of diseases and insect pests,which can improve the yield and quality of tomato.展开更多
ZTE Corporation is China’s largest listedtelecommunications equipment provider spe-cialized in offering a full range of tailor-madesolutions for customers in high-,middle-andlow-end markets.
As the main equipment of flue gas dedusting in coal fired boiler,electrostatic precipitator(ESP)can meet the requirements of emission standard for air pollutants from coal-fired power plants through improving the effi...As the main equipment of flue gas dedusting in coal fired boiler,electrostatic precipitator(ESP)can meet the requirements of emission standard for air pollutants from coal-fired power plants through improving the efficiency of ESP and combining with desulfurization system while not installing wet ESP(WESP).This paper introduces the modifications of ESP cathode structure to improve the efficiency of dust collection by reducing the secondary dust loss at cathode.The application of cathode dust collection provides a reference for the improvement of ESP dust collection efficiency.展开更多
financed by the Special Program of Super Rice of Ministry of Agriculture, China (02318802013231);the National Public Services Sectors (Agricultural) Research Projects, Ministry of Agriculture, China (201303102);...financed by the Special Program of Super Rice of Ministry of Agriculture, China (02318802013231);the National Public Services Sectors (Agricultural) Research Projects, Ministry of Agriculture, China (201303102);the Great Technology Project of Ningbo, China (2013C11001)展开更多
[Objectives]To investigate the application effect of compound microbial fertilizer on crops.[Methods]Livestock and poultry breeding waste,rapeseed cake and peanut straw were fully decomposed,and then added with compou...[Objectives]To investigate the application effect of compound microbial fertilizer on crops.[Methods]Livestock and poultry breeding waste,rapeseed cake and peanut straw were fully decomposed,and then added with compound functional microbial inoculum to produce Aisi Si/TE(active chelated silicon/trace element)compound microbial fertilizer,which was used to conduct 10%nitrogen reduction alternative fertilization experiment on rice.[Results]The yield of rice applied with 225 kg/ha Aisi Si/TE compound bacterial fertilizer was 7203 kg/ha,increased by 5.4%,6.9%and 46.9%,respectively compared to those of rice applied with 225 kg/ha inactivated Aisi Si/TE compound microbial fertilizer,conventional fertilization and blank control(P<0.01).Application of Aisi Si/TE compound microbial fertilizer to rice improved soil organic matter and effective nutrient content and showed obvious effect of saving nitrogen and increasing yield and income.In addition,it provided a good micro-ecological environment,passivated and solidified heavy metals,effectively reduced the biological mobility of heavy metals,and greatly reduced the cadmium content in rice.[Conclusions]Application of Aisi Si/TE compound microbial fertilizer is beneficial to improving the quality of agricultural products.展开更多
According to data collected from 1935 statistics-worthy Chinese chemical fibre enterprises surveyed by National Bureau of Statistics of China, the total profits reached CNY8.066 billion in Jan. -May, 2010, up 200.08 p...According to data collected from 1935 statistics-worthy Chinese chemical fibre enterprises surveyed by National Bureau of Statistics of China, the total profits reached CNY8.066 billion in Jan. -May, 2010, up 200.08 per cent y/y, 234.78 percentage points higher than the Jan.-May 2009 period. Technology improvement and industrial structural adjustment played a very major role on profi t growth.展开更多
Nitrogen (N) is one of most important nutrients for crop production, which makes up 1%-5% of total plant dry matter (Marschner, 2012). Due to the limited availability of N in soil, application of N fertilizers has...Nitrogen (N) is one of most important nutrients for crop production, which makes up 1%-5% of total plant dry matter (Marschner, 2012). Due to the limited availability of N in soil, application of N fertilizers has been an important agronomic practice to increase crop yield. However, over-application of N fertilizers has caused pollution of N in soil, water and air. It was estimated that the nitrogen use efficiency (NUE, the total biomass or grain yield produced per unit of applied fertilizer N) in cereal crops is as low as 33% (Raun and Johnson, 1999). Therefore, improving NUE together with reducing application of N fertilizers is an important issue for environment and sustainable production of crops. This is especially important for rice, which is a staple food for half population in the world.展开更多
Most of the important agronomic traits in crop plants, such as yield, quality and stress response, are quantitative and jointly controlled by many genomic loci or major genes. Improving these complex traits depends on...Most of the important agronomic traits in crop plants, such as yield, quality and stress response, are quantitative and jointly controlled by many genomic loci or major genes. Improving these complex traits depends on the combination of beneficial alleles at the quantitative trait loci (QTLs). However, the conventional cross breeding method is extremely time-consuming and laborious for pyramiding multiple QTLs. In certain cases, this approach might be technically difficult because of close linkage between genes separately responsible for desirable and undesirable traits.展开更多
In mammalians, the state of a somatic cell can be reversed from the terminal state to the totipotent state by means of somatic cell nuclear transfer (SCNT) (Gurdon, 1962) or induced pluripotent stem cells (iPSCs...In mammalians, the state of a somatic cell can be reversed from the terminal state to the totipotent state by means of somatic cell nuclear transfer (SCNT) (Gurdon, 1962) or induced pluripotent stem cells (iPSCs) (Takahashi and Yamanaka, 2006). The DNA methylation and transcriptome profiles of embryonic stern cells (ESCs) derived from SCNT embryos (NT-ESCs) correspond closely to those of ESCs derived from in vitro fertilization embryos (IVF- ESCs). In contrast, iPSCs differ from both NT-ESCs and IVF-ESCs in that they retain the residual DNA methylation patterns of their parental somatic cells. As SCNT can be used to faithfully reprogram human somatic cells to pluripotency, it is ideal for cell replacement therapies (Ma et al., 2014). Following the successful production of the first human NT-ESCs (Tachibana et al., 2013) and the later gen- eration of human NT-ESCs based on cells from elderly adults or pa- tient cells (Chung et al., 2014; Yamada et al., 2014), a version of the SCNT technique for human therapeutics comes closer to reality. However, no matter what animal species or donor cell types are used in the cloned process, the cloning efficiency remains undesir- able. Besides, there are many phenotypic abnormalities in cloned animals, containing frequent embryonic and perinatal death and placentomegaly, and the underlying mechanisms remain unclear (Yang et al, 2007).展开更多
Heightened interests have been laid at the preliminary design and optimization of the centrifugal compressor for the fuel cell vehicle.The centrifugal compressor for fuel cell vehicle is driven by a high-speed motor;h...Heightened interests have been laid at the preliminary design and optimization of the centrifugal compressor for the fuel cell vehicle.The centrifugal compressor for fuel cell vehicle is driven by a high-speed motor;however,the limit of the motor speed makes the flow passage of the impeller long and narrow,which leads to a serious tip leakage loss.Serious tip leakage loss deteriorates the compressor performance.In this paper,3-D numerical simulations were carried out with the aim of investigating the tip leakage loss in a prototype centrifugal compressor for a 100 kW fuel cell stack.The results revealed that the mixing loss caused by the interaction between the tip leakage vortex and the downstream tip leakage flow contributed to the major part of the tip leakage loss.The path of the tip leakage vortex almost followed the streamwise direction,while the downstream tip leakage flow exhibited strong circumferential momentum,which referred to the fact that they were nearly orthogonal.Therefore,a flow control approach,which was realized by enhancing the blade loading around the leading edge of blade tips in this paper,was proposed to decrease the interaction angle between the tip leakage vortex and the downstream tip leakage flow and then mitigate mixing loss by changing the flow direction of the tip leakage vortex.The results showed a smaller interaction angle was achieved in the optimized impeller compared with the baseline one.Meanwhile,the efficiency was also improved by 1.30%at design condition and the maximum efficiency improvement could be up to 10%at large mass flow condition of 92000 r/min.Being manufactured and tested,the optimized compressor was proved to achieve an isentropic efficiency of 75.84%at design condition.展开更多
The successful market uptake of all-electric propulsion systems is closely related to the performance metrics of the electrical motor used within.In light of this,various road-maps have been set for the next two decad...The successful market uptake of all-electric propulsion systems is closely related to the performance metrics of the electrical motor used within.In light of this,various road-maps have been set for the next two decades by aerospace and automotive bodies targeting ambitious future targets of the motor's power densities and efficiencies.In achieving motors with such step-improvement performance metrics,often the thermal management is a key challenge.In this paper,a cooling structure for a propulsion motor of solar unmanned aircraft is proposed which combines the stator windings with heat pipes,and which is shown to simultaneously improve the heat dissipation as well as the efficiency.This paper firstly determines the heat transfer characteristic of the heat pipe experimentally which is then used in the development of a bespoke thermal network model of the motor.The effects of the cooling structure on the motor's temperature rise,copper losses,torque,and efficiency are studied in detail.Finally,a prototype is developed and a test platform is built.The experimental results are consistent with the analytical result,verifying the correctness of the thermal network model and the benefits of the proposed mechanism.Compared to the motor without heat pipes,the temperature rise of the motor is reduced by 35%,while its efficiency is improved by a significant 1.5%.展开更多
Organic–inorganic metal halide perovskites have attained extensive attention owing to their outstanding photovoltaic performances,but the existence of numerous defects in crystalline perovskites is still a serious co...Organic–inorganic metal halide perovskites have attained extensive attention owing to their outstanding photovoltaic performances,but the existence of numerous defects in crystalline perovskites is still a serious constraint for the further development of perovskite solar cells(PSCs).In particular,the rapid crystallization guided by anti-solvents leads to plenty of surficial and interfacial defects in perovskite films.Herein,we report the adoption of a pseudo-halide anion based ionic liquid additive,1-butyl-3-methylimidazolium thiocyanate(BMIMSCN)for growing ternary cation(CsFAMA,where FA=formamidinium and MA=methylammonium)perovskites with large-scale crystal grains and strong preferential orientation via the enhanced Ostwald ripening.Meanwhile,a novel halide-free passivator,benzylammonium formate(BAFa),was employed as a buffering layer on the perovskite films to suppress surface-dominated charge recombination.As a result,the cooperative effects of BMIMSCN additive and BAFa passivator lead to significant enhancements on fluorescence lifetime(from 79.41 to 201.01 ns),open-circuit voltage(from 1.13 to 1.19 V),photoelectric conversion efficiency(from 18.90%to 22.33%).Moreover,the BMIMSCN/BAFa-CsFAMA PSCs demonstrated greatly improved stability against moisture and heat.This work suggests a promising strategy to improve the quality of perovskite materials via reducing the surficial and interfacial defects by the synergistic effects of lattice doping and interface engineering.展开更多
This paper constructs a two-stage sequential game model to shed light on the spillover effect of inward FDI on the efficiency of domestic firms in host countries.Our model shows that,given an optimal joint-venture pol...This paper constructs a two-stage sequential game model to shed light on the spillover effect of inward FDI on the efficiency of domestic firms in host countries.Our model shows that,given an optimal joint-venture policy made by foreign firms,the impact of the spillover effect of inward FDI is contingent upon the productivity gap between the domestic firms and foreign ones.In particular,we demonstrate that the spillover effect of inward FDI varies negatively with the productivity gap between domestic lowproductivity firms and foreign firms but works in the opposite way for high-productivity firms.This suggests that once the productivity gap widens,the entry of foreign firms will increase the efficiency of high-productivity firms but reduce the efficiency of lowproductivity firms.In support of our theoretical model,we provide robust empirical results by using the dataset of annual survey of Chinese industrial enterprises.展开更多
In a recent paper, an efficient semi-implicit finite element scheme for 2-dimensional tidal flow computations is proposed. In that scheme, each term of the governing equations, rather than each dependent variable, is ...In a recent paper, an efficient semi-implicit finite element scheme for 2-dimensional tidal flow computations is proposed. In that scheme, each term of the governing equations, rather than each dependent variable, is ex- panded in terms of the unknown nodal values. Simpson's rule ix used for numerical integration to make the mass matrix diagonal. The friction terms are represented semi-implicitly to improve stability, but no additional compu- tational effort is required. The shortcomings of this scheme are that the time-stepping scheme is only first-order ae- curate and artificial smoothing is required to control the numerical noise. In this paper, the previous scheme is im- proved by including the eddy viscosity terms in the governing equations to replace artificial smoothing in noise con- trol and the time-stepping scheme is modified to make it second-order accurate. These improvements can be achieved with only a slight increase in computational effort. The test cases used previously to validate the former scheme are again employed to test the present scheme.展开更多
Hybrid Si/SiC switches constituting a parallel connection of a lower current rated SiC MOSFET and a higher current rated Si IGBT are becoming very attractive solution for designing high frequency and high-power densit...Hybrid Si/SiC switches constituting a parallel connection of a lower current rated SiC MOSFET and a higher current rated Si IGBT are becoming very attractive solution for designing high frequency and high-power density power electronic converters.Due to the complementary nature of Si IGBT devices(smaller inverter cost and smaller conduction loss)and SiC devices(smaller switching loss and higher junction temperature capability),these novel switch device configurations enable a good tradeoff between cost and efficiency for high power converter applications.One such recent application of hybrid Si/SiC switches for efficiency-cost optimization is an Si/SiC hybrid switch based ANPC inverter proposed in Ref.[30].In Ref.[30]the topology structure,modulation strategy and the efficiency-cost benefits of the proposed ANPC inverter is presented.In this paper a precise electro-thermal power loss model for this ANPC inverter topology will be presented based on the modulation strategy of the inverter and the operating characteristics of the Si/SiC hybrid switches.The power loss model development takes into account how the current sharing between the two internal devices of the Si/SiC hybrid switches and their corresponding gate control method affects their power loss.A brief introduction to the topology structure and operation principle of the Si/SiC based ANPC inverter is first highlighted to provide context for readers and then a detailed description of the proposed electro-thermal power loss model is presented.The precision of the electro-thermal power loss model introduced in this paper is then validated using experimentally measured energy loss,device temperature and inverter efficiency data.展开更多
文摘When artificial waterfalls are built in gardens,leaves from trees or vegetation often fall into the water storage pool and block the pipelines,requiring regular cleaning of pipelines.This not only increases the manpower needed for maintenance but also disrupts the use of the waterfalls.Therefore,it is necessary to design a new type of artificial waterfall that is suitable for gardens.The waterfall should incorporate features that make cleaning easier,including filter plates and water funnels to prevent clogging caused by fallen leaves and debris.
基金2022 University-Level General Project“Empowering Precise Ideological and Political Education in Higher Education with Educational Digitalization”(Project number:jsesd202209)。
文摘The study explores how educational digitalization enables the precise development of ideological and political education in colleges and universities.Digital transformation enables colleges and universities to accurately define educational objectives,content strategies,effect evaluation,and process management,and realize the precision and intelligence of ideological and political education.The application of big data technology enhances the data-oriented thinking of teachers and students,promotes the accurate application of data,and improves the efficiency of ideological and political education.The research also prospected a new vision of the digital construction of ideological and political courses and clarified the theoretical and practical path of the implementation and evaluation mode of ideological and political courses under digital empowerment.Education digitalization enables precise ideological and political education,which is a key way to promote the innovative development of ideological and political education in colleges and universities and will strongly support the improvement of the overall quality of higher education and the training of excellent talents.
基金National Innovation and Entrepreneurship Training Project“Time Bay-A Group Elderly Care Service Platform Based on Internet of Things Technology”(S202013836008X)Chongqing Education Commission Science and Technology Research Program Youth Project 2021(KJQN202105501)。
文摘Internet of Things(IoT)technology is widely used in various fields,and its application in elderly care services has been highlighted in recent years.This study aims to explore how IoT technology can improve the efficiency of group-based elderly care services.The concept,characteristics,and current application status of IoT technology in elderly care services were introduced.Secondly,the characteristics and needs of group elderly care services were analyzed,including advantages and challenges,as well as the expectations and needs of the elderly for elderly care services.The evaluation methods and future development directions of IoT technology in improving the efficiency of group elderly care services were discussed,including data collection and analysis methods,selection and measurement of efficiency evaluation indicators,challenges,and development directions.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51578247).
文摘A two⁃port encapsulated low⁃contrast grating with suppressed zeroth order under normal incidence is described in this paper.Based on such grating configuration,the improved efficiency and spectral bandwidth of the first order for TE and TM polarizations with a designed period of 1860 nm can be obtained.On the one hand,some of the accurate grating parameters were numerically optimized utilizing a rigorous coupled⁃wave analysis;on the other hand,the inherent physical mechanism suppressing the zeroth order through an encapsulated fused⁃silica grating was adequately interpreted on account of a simplified modal method.Encapsulated grating with a cover layer cannot be simply considered as adding a coating on it.Compared with reported surface⁃relief grating,all parameters of encapsulated grating should be re⁃optimized and the optimized performances of encapsulated grating were greatly improved.Therefore,the encapsulated grating can be potentially applied in writing fiber Bragg gratings.
文摘The article describes the possibilities of application of simulation modeling for the analysis of infrastructure and technology of transport services of enterprises. The main technological and possible economic effects for the enterprises arising at performance of modeling of a transport component of their work are resulted.
文摘According to the technical approach of green production and yield increase pattern,green,pollution-free,quality and efficiency improvement can be achieved by reducing nitrogen,controlling phosphorus and stabilizing potassium,replenishing sulfur,zinc,iron,manganese and boron from the aspects of controlling fertilizer,drug and water.The main measures include combination use of organic and inorganic fertilizer,effective control of the amount of nitrogen and phosphate fertilizer,reduction of the application amount of chemical fertilizers and pesticides,and rational crop rotation to reduce the occurrence of diseases and insect pests,which can improve the yield and quality of tomato.
文摘ZTE Corporation is China’s largest listedtelecommunications equipment provider spe-cialized in offering a full range of tailor-madesolutions for customers in high-,middle-andlow-end markets.
文摘As the main equipment of flue gas dedusting in coal fired boiler,electrostatic precipitator(ESP)can meet the requirements of emission standard for air pollutants from coal-fired power plants through improving the efficiency of ESP and combining with desulfurization system while not installing wet ESP(WESP).This paper introduces the modifications of ESP cathode structure to improve the efficiency of dust collection by reducing the secondary dust loss at cathode.The application of cathode dust collection provides a reference for the improvement of ESP dust collection efficiency.
基金financed by the Special Program of Super Rice of Ministry of Agriculture, China (02318802013231)the National Public Services Sectors (Agricultural) Research Projects, Ministry of Agriculture, China (201303102)the Great Technology Project of Ningbo, China (2013C11001)
文摘financed by the Special Program of Super Rice of Ministry of Agriculture, China (02318802013231);the National Public Services Sectors (Agricultural) Research Projects, Ministry of Agriculture, China (201303102);the Great Technology Project of Ningbo, China (2013C11001)
文摘[Objectives]To investigate the application effect of compound microbial fertilizer on crops.[Methods]Livestock and poultry breeding waste,rapeseed cake and peanut straw were fully decomposed,and then added with compound functional microbial inoculum to produce Aisi Si/TE(active chelated silicon/trace element)compound microbial fertilizer,which was used to conduct 10%nitrogen reduction alternative fertilization experiment on rice.[Results]The yield of rice applied with 225 kg/ha Aisi Si/TE compound bacterial fertilizer was 7203 kg/ha,increased by 5.4%,6.9%and 46.9%,respectively compared to those of rice applied with 225 kg/ha inactivated Aisi Si/TE compound microbial fertilizer,conventional fertilization and blank control(P<0.01).Application of Aisi Si/TE compound microbial fertilizer to rice improved soil organic matter and effective nutrient content and showed obvious effect of saving nitrogen and increasing yield and income.In addition,it provided a good micro-ecological environment,passivated and solidified heavy metals,effectively reduced the biological mobility of heavy metals,and greatly reduced the cadmium content in rice.[Conclusions]Application of Aisi Si/TE compound microbial fertilizer is beneficial to improving the quality of agricultural products.
文摘According to data collected from 1935 statistics-worthy Chinese chemical fibre enterprises surveyed by National Bureau of Statistics of China, the total profits reached CNY8.066 billion in Jan. -May, 2010, up 200.08 per cent y/y, 234.78 percentage points higher than the Jan.-May 2009 period. Technology improvement and industrial structural adjustment played a very major role on profi t growth.
文摘Nitrogen (N) is one of most important nutrients for crop production, which makes up 1%-5% of total plant dry matter (Marschner, 2012). Due to the limited availability of N in soil, application of N fertilizers has been an important agronomic practice to increase crop yield. However, over-application of N fertilizers has caused pollution of N in soil, water and air. It was estimated that the nitrogen use efficiency (NUE, the total biomass or grain yield produced per unit of applied fertilizer N) in cereal crops is as low as 33% (Raun and Johnson, 1999). Therefore, improving NUE together with reducing application of N fertilizers is an important issue for environment and sustainable production of crops. This is especially important for rice, which is a staple food for half population in the world.
基金supported by Genetically Modified Breeding Major Projects(No.2016ZX08010-002-008)the National Natural Science Foundation of China(Nos.31501239 and 31401454)
文摘Most of the important agronomic traits in crop plants, such as yield, quality and stress response, are quantitative and jointly controlled by many genomic loci or major genes. Improving these complex traits depends on the combination of beneficial alleles at the quantitative trait loci (QTLs). However, the conventional cross breeding method is extremely time-consuming and laborious for pyramiding multiple QTLs. In certain cases, this approach might be technically difficult because of close linkage between genes separately responsible for desirable and undesirable traits.
基金supported by grants from the National Natural Science Foundation of China(No.31471395)to Q.Z.the Key Research Projects of the Frontier Science of the Chinese Academy of Sciences(QYZDY-SSW-SMC002)to Q.Z
文摘In mammalians, the state of a somatic cell can be reversed from the terminal state to the totipotent state by means of somatic cell nuclear transfer (SCNT) (Gurdon, 1962) or induced pluripotent stem cells (iPSCs) (Takahashi and Yamanaka, 2006). The DNA methylation and transcriptome profiles of embryonic stern cells (ESCs) derived from SCNT embryos (NT-ESCs) correspond closely to those of ESCs derived from in vitro fertilization embryos (IVF- ESCs). In contrast, iPSCs differ from both NT-ESCs and IVF-ESCs in that they retain the residual DNA methylation patterns of their parental somatic cells. As SCNT can be used to faithfully reprogram human somatic cells to pluripotency, it is ideal for cell replacement therapies (Ma et al., 2014). Following the successful production of the first human NT-ESCs (Tachibana et al., 2013) and the later gen- eration of human NT-ESCs based on cells from elderly adults or pa- tient cells (Chung et al., 2014; Yamada et al., 2014), a version of the SCNT technique for human therapeutics comes closer to reality. However, no matter what animal species or donor cell types are used in the cloned process, the cloning efficiency remains undesir- able. Besides, there are many phenotypic abnormalities in cloned animals, containing frequent embryonic and perinatal death and placentomegaly, and the underlying mechanisms remain unclear (Yang et al, 2007).
基金the National Key R&D Program of China(Grant No.2018YFB0106502)Open Fund of Science and Technology on Thermal Energy and Power Laboratory(No.TPL2017AB008).
文摘Heightened interests have been laid at the preliminary design and optimization of the centrifugal compressor for the fuel cell vehicle.The centrifugal compressor for fuel cell vehicle is driven by a high-speed motor;however,the limit of the motor speed makes the flow passage of the impeller long and narrow,which leads to a serious tip leakage loss.Serious tip leakage loss deteriorates the compressor performance.In this paper,3-D numerical simulations were carried out with the aim of investigating the tip leakage loss in a prototype centrifugal compressor for a 100 kW fuel cell stack.The results revealed that the mixing loss caused by the interaction between the tip leakage vortex and the downstream tip leakage flow contributed to the major part of the tip leakage loss.The path of the tip leakage vortex almost followed the streamwise direction,while the downstream tip leakage flow exhibited strong circumferential momentum,which referred to the fact that they were nearly orthogonal.Therefore,a flow control approach,which was realized by enhancing the blade loading around the leading edge of blade tips in this paper,was proposed to decrease the interaction angle between the tip leakage vortex and the downstream tip leakage flow and then mitigate mixing loss by changing the flow direction of the tip leakage vortex.The results showed a smaller interaction angle was achieved in the optimized impeller compared with the baseline one.Meanwhile,the efficiency was also improved by 1.30%at design condition and the maximum efficiency improvement could be up to 10%at large mass flow condition of 92000 r/min.Being manufactured and tested,the optimized compressor was proved to achieve an isentropic efficiency of 75.84%at design condition.
基金the Natural Science Foundation for Outstanding Young Scholar[grant numbers 52122704]the National Natural Science Foundation of China[grant numbers U2141224 and 52077044].
文摘The successful market uptake of all-electric propulsion systems is closely related to the performance metrics of the electrical motor used within.In light of this,various road-maps have been set for the next two decades by aerospace and automotive bodies targeting ambitious future targets of the motor's power densities and efficiencies.In achieving motors with such step-improvement performance metrics,often the thermal management is a key challenge.In this paper,a cooling structure for a propulsion motor of solar unmanned aircraft is proposed which combines the stator windings with heat pipes,and which is shown to simultaneously improve the heat dissipation as well as the efficiency.This paper firstly determines the heat transfer characteristic of the heat pipe experimentally which is then used in the development of a bespoke thermal network model of the motor.The effects of the cooling structure on the motor's temperature rise,copper losses,torque,and efficiency are studied in detail.Finally,a prototype is developed and a test platform is built.The experimental results are consistent with the analytical result,verifying the correctness of the thermal network model and the benefits of the proposed mechanism.Compared to the motor without heat pipes,the temperature rise of the motor is reduced by 35%,while its efficiency is improved by a significant 1.5%.
基金the National Key R&D Program of China(No.2017YFA0208200)the National Natural Science Foundation of China(Nos.22022505,21872069,and 22109069)+3 种基金the Fundamental Research Funds for the Central Universities of China(Nos.020514380266,020514380272,and 020514380274)the Scientific and Technological Innovation Special Fund for Carbon Peak and Carbon Neutrality of Jiangsu Province(BK20220008)the Nanjing International Collaboration Research Program(Nos.202201007 and 2022SX00000955)the Suzhou Gusu Leading Talent Program of Science and Technology Innovation and Entrepreneurship in Wujiang District(No.ZXL2021273).
文摘Organic–inorganic metal halide perovskites have attained extensive attention owing to their outstanding photovoltaic performances,but the existence of numerous defects in crystalline perovskites is still a serious constraint for the further development of perovskite solar cells(PSCs).In particular,the rapid crystallization guided by anti-solvents leads to plenty of surficial and interfacial defects in perovskite films.Herein,we report the adoption of a pseudo-halide anion based ionic liquid additive,1-butyl-3-methylimidazolium thiocyanate(BMIMSCN)for growing ternary cation(CsFAMA,where FA=formamidinium and MA=methylammonium)perovskites with large-scale crystal grains and strong preferential orientation via the enhanced Ostwald ripening.Meanwhile,a novel halide-free passivator,benzylammonium formate(BAFa),was employed as a buffering layer on the perovskite films to suppress surface-dominated charge recombination.As a result,the cooperative effects of BMIMSCN additive and BAFa passivator lead to significant enhancements on fluorescence lifetime(from 79.41 to 201.01 ns),open-circuit voltage(from 1.13 to 1.19 V),photoelectric conversion efficiency(from 18.90%to 22.33%).Moreover,the BMIMSCN/BAFa-CsFAMA PSCs demonstrated greatly improved stability against moisture and heat.This work suggests a promising strategy to improve the quality of perovskite materials via reducing the surficial and interfacial defects by the synergistic effects of lattice doping and interface engineering.
文摘This paper constructs a two-stage sequential game model to shed light on the spillover effect of inward FDI on the efficiency of domestic firms in host countries.Our model shows that,given an optimal joint-venture policy made by foreign firms,the impact of the spillover effect of inward FDI is contingent upon the productivity gap between the domestic firms and foreign ones.In particular,we demonstrate that the spillover effect of inward FDI varies negatively with the productivity gap between domestic lowproductivity firms and foreign firms but works in the opposite way for high-productivity firms.This suggests that once the productivity gap widens,the entry of foreign firms will increase the efficiency of high-productivity firms but reduce the efficiency of lowproductivity firms.In support of our theoretical model,we provide robust empirical results by using the dataset of annual survey of Chinese industrial enterprises.
文摘In a recent paper, an efficient semi-implicit finite element scheme for 2-dimensional tidal flow computations is proposed. In that scheme, each term of the governing equations, rather than each dependent variable, is ex- panded in terms of the unknown nodal values. Simpson's rule ix used for numerical integration to make the mass matrix diagonal. The friction terms are represented semi-implicitly to improve stability, but no additional compu- tational effort is required. The shortcomings of this scheme are that the time-stepping scheme is only first-order ae- curate and artificial smoothing is required to control the numerical noise. In this paper, the previous scheme is im- proved by including the eddy viscosity terms in the governing equations to replace artificial smoothing in noise con- trol and the time-stepping scheme is modified to make it second-order accurate. These improvements can be achieved with only a slight increase in computational effort. The test cases used previously to validate the former scheme are again employed to test the present scheme.
文摘Hybrid Si/SiC switches constituting a parallel connection of a lower current rated SiC MOSFET and a higher current rated Si IGBT are becoming very attractive solution for designing high frequency and high-power density power electronic converters.Due to the complementary nature of Si IGBT devices(smaller inverter cost and smaller conduction loss)and SiC devices(smaller switching loss and higher junction temperature capability),these novel switch device configurations enable a good tradeoff between cost and efficiency for high power converter applications.One such recent application of hybrid Si/SiC switches for efficiency-cost optimization is an Si/SiC hybrid switch based ANPC inverter proposed in Ref.[30].In Ref.[30]the topology structure,modulation strategy and the efficiency-cost benefits of the proposed ANPC inverter is presented.In this paper a precise electro-thermal power loss model for this ANPC inverter topology will be presented based on the modulation strategy of the inverter and the operating characteristics of the Si/SiC hybrid switches.The power loss model development takes into account how the current sharing between the two internal devices of the Si/SiC hybrid switches and their corresponding gate control method affects their power loss.A brief introduction to the topology structure and operation principle of the Si/SiC based ANPC inverter is first highlighted to provide context for readers and then a detailed description of the proposed electro-thermal power loss model is presented.The precision of the electro-thermal power loss model introduced in this paper is then validated using experimentally measured energy loss,device temperature and inverter efficiency data.