With the global promotion of LED lighting products, the health and safety of LED products has drawn wider attention. This paper systematically introduces the ergonomic evaluation (methods and indicators) svstem for ...With the global promotion of LED lighting products, the health and safety of LED products has drawn wider attention. This paper systematically introduces the ergonomic evaluation (methods and indicators) svstem for heahh and comfort which differs from the traditional manpowered physical detection, and sketches out the evaluation indicators and its industrialization prospect.展开更多
A laboratory-based work was conducted on development, biometry (cyst diameter, hatching efficiency and hatching percentage) and survival rate of Artemia franciscana at 35 ppt using natural brine water under constant...A laboratory-based work was conducted on development, biometry (cyst diameter, hatching efficiency and hatching percentage) and survival rate of Artemia franciscana at 35 ppt using natural brine water under constant aeration facilities. The experiment was carried out for both chorionic and decapsulated cysts. There was a significant increase in hatching output of the decapsulated cysts than the chorionic cysts. The survival rate was counted only for the chorionic cysts because nauplii hatched from decapsulated cysts died after four days of incubation before reaching the adult stage. Untill now the Artemia cysts are imported from abroad. Though the prospect of mass production of Artemia in Bangladesh is feasible but there needs to be more studies done.展开更多
To some extent, college English teaching management affects the success or failure of university education. This paper analyzes the current status of research and management, the use of management to clarify the meani...To some extent, college English teaching management affects the success or failure of university education. This paper analyzes the current status of research and management, the use of management to clarify the meaning of the five elements of law, based on the induction of the one-sided understanding, setting single, formal training, and simplistic assessment of the four questions, and start from the two elements of teaching and learning around how to teach, how to learn, how assessment of the problem, explore the three management initiatives, with a view of college English teaching management plays a certain significance.展开更多
Efforts to speed up China's coal bed methane (CBM) exploration developments related to production safety, optimization of energy structures, prevention of energy waste and reduction of greenhouse gas emissions are...Efforts to speed up China's coal bed methane (CBM) exploration developments related to production safety, optimization of energy structures, prevention of energy waste and reduction of greenhouse gas emissions are all of great significance. In order to strengthen CBM exploration and development in China and to encourage increased growth in the CBM industry, we firstly give a general overview of the recent technological innovations and other developments in CBM exploration in the U.S., Canada and other countries. Using this background information as the starting point, we further present observations and analyses of CBM exploration and development, preferential policies, technical support and implications of R&D for CBM development in China. The results show that the problems related to CBM exploration technology development and lack of a complete set of management policies are still the major issues slowing down the growth of domestic CBM industry. Development of resource exploration and technology, R&D and establishment of favorable government policy to support the industry and the creation of a relevant information platform, etc. are finally recommended.展开更多
ZrO2-MnO2-ZnO supports were prepared by the co-precipitation method,and then Ni-Na/ZrO2-MnO2-ZnO catalysts were prepared by the impregnation method.In this paper,the reactions to synthesize methyl isopropyl ketone and...ZrO2-MnO2-ZnO supports were prepared by the co-precipitation method,and then Ni-Na/ZrO2-MnO2-ZnO catalysts were prepared by the impregnation method.In this paper,the reactions to synthesize methyl isopropyl ketone and diethyl ketone by the one-step synthesis method over this catalyst were studied,and meanwhile,the impact of the catalyst preparation conditions and the reaction conditions on catalyst performance was also investigated.It was observed that under the conditions when Ni loading was 25%,calcination temperature was 400℃ and reduction temperature was 410℃,this catalyst had good catalytic performance on the reaction.The suitable reaction conditions were achieved:reaction temperature was 400℃;reaction at atmospheric pressure;liquid hourly space velocity of raw material of 0.5 h 1 ;and the molar ratio of(methanol)/(methyl ethyl ketone)/(water) was equal to 1/1/1.Under such conditions,the conversion of methyl ethyl ketone could achieve 41.7%,and the overall selectivity of methyl isopropyl ketone and diethyl ketone could achieve 83.3%,which was comparable to the conversion of 38.1% and the selectivity of 82.2% achieved by using palladium as the active material.The good stability made this catalyst have good prospects for industrial application.展开更多
In recent years, with the rapid growth in demand for commercial launches, space institutions like NASA have been succeeded in the commercialization of aerospace services. According to the latest development trends on ...In recent years, with the rapid growth in demand for commercial launches, space institutions like NASA have been succeeded in the commercialization of aerospace services. According to the latest development trends on international commercial aerospace services and the current development status of domestic commercial aerospace services, suggestions on the development of China's commercial aerospace services based on policies, development modes and technical innovation are given.展开更多
China is the only one country in the world with more than one hundred million people who aged over 60. With the dramatically increasing of population aging speed, the traditional endowment pattern with the element of ...China is the only one country in the world with more than one hundred million people who aged over 60. With the dramatically increasing of population aging speed, the traditional endowment pattern with the element of family model has a weakening trend and does not satisfy the demand of urban elderly diversified and multi-level pension. Thus, pensions that occupy at home are becoming the best choice of the urban pension mode in China. The paper will describe the meaning, situation and prospects of the home endowment and demonstrate the significance of developing the home endowment project in China. Additionally, the paper will discuss the future endowment model from the aspects of the government organization, scientific planning and functional shifts.展开更多
This article classifies the seawater desalination technology into four types of hot method, membrane method, electric field method and solvent method. Electric field method and solvent method still remain experimental...This article classifies the seawater desalination technology into four types of hot method, membrane method, electric field method and solvent method. Electric field method and solvent method still remain experimental stage, while hot method and membrane method have been realized in commercialization but are difficult to be promoted. The problem lies in high water-producing cost. It is difficult for membrane method seawater desalination technology to reduce the water-producing cost. The heat utilization efficiency is not high for the current hot method seawater desalination technology and there is large amount of heat lost with the emission of concentrated seawater. The new hot method seawater desalination technology and new solar-powered seawater desalination technology can divide the seawater into fresh water and solid salt without any emission of concentrated seawater so that the heat utilization efficiency can reach theoretical limit to multiply reduce the water-producing cost. They will become the mainstream technology for seawater desalination and can totally eliminate the global water crisis.展开更多
Energy conversion and utilization, particularly carbon-based fuel burning in air phase, have caused great environmental pollution and serious problems to society. The reactions in water phase may have the potential to...Energy conversion and utilization, particularly carbon-based fuel burning in air phase, have caused great environmental pollution and serious problems to society. The reactions in water phase may have the potential to realize clean and efficient energy conversion and utilization. Coal gasification in supercritical water is a typical carbon-based fuel conversion process in water phase, and it takes the advantages of the unique chemical and physical properties of supercritical water to convert organic matter in coal to H2 and CO2. N, S, P, Hg and other elements are deposited as inorganic salts to avoid pollution emission. The State Key Laboratory of Multiphase Flow in Power Engineering has obtained extensive experimental and theoretical results based on coal gasification in supercritical water. Supercritical water fluidized bed reactor was developed for coal gasification and seven kinds of typical feedstock were selected. The hydrogen yield covers from 0.67 to 1.74 Nm3/kg and the carbon gasification efficiency is no less than 97%. This technology has a bright future in industrialization not only in electricity generation but also in hydrogen production and high value-added chemicals. Given the gas yield obtained in laboratory-scale unit, the hydrogen production cost is U.S.$ 0.111 Nm3 when the throughput capacity is 2000 t/d. A novel thermodynamic cycle power generation system based on coal gasification in supercritical water was proposed with the obvious advantages of high coal-electricity conversion efficiency and zero pollutant emission. The cost of U.S.$ 3.69 billion for desulfuration, denitration and dust removal in China in 2013 would have been saved with this technology. Five kinds of heat supply methods are analyzed and the rates of return of investment are roughly estimated. An integrated cooperative innovation center called a new type of high-efficient coal gasification technology and its large-scale utilization was founded to enhance the industrialization of the technology vigorously.展开更多
Much has been learned in the past 40 years about the great diversity of the internal structure and geochemical compositions of Phanerozoic ophiolites, indicating that these on-land fragments of ancient oceanic lithosp...Much has been learned in the past 40 years about the great diversity of the internal structure and geochemical compositions of Phanerozoic ophiolites, indicating that these on-land fragments of ancient oceanic lithosphere formed in distinctly different tectonic settings during their igneous evolution. Recent studies in Archean and Proterozoic greenstone belts have shown that the Precambrian rock record may also include exposures of a diverse suite of ophiolite complexes as part of craton development in the early history of the Earth. We review the salient features of the Precambrian ophiolite record to highlight what has been learned about Precambrian oceanic spreading systems since the original Penrose definition of ophiolites in 1972. Some of the diagnostic, characteristic, typical, and rare aspects of ophiolites of all ages are presented in a table in order to help determine if tectonically deformed and metamophosed sequences in Precambrian shield areas may be considered as ophiolites. The results of this comparative study are important in that they enable researchers to more realistically characterize allochthonous mafic/ultramafic rock sequences as ophiolitic or non-ophiolitic. This approach is more deterministic in contrast to some other arbitrary classification schemes requiring three or four of the Penrose-style ophiolitic units to be present in the Precambrian record for a specific rock sequence to be considered ophiolitic. Once these tectonic fragments are recognized as remnants of ancient oceanic lithosphere, great progress shall be made in understanding early Earth history. We discuss the significance and implications of the Precambrian ophiolite record to constrain the mode and nature of the plate tectonics that operated in deep time.展开更多
A harmonic vortex beam is a typical vector beam with a helical wavefront at harmonic frequencies(e.g.,second and third harmonics). It provides an additional degree of freedom beyond spin-and orbitalangular momentum, w...A harmonic vortex beam is a typical vector beam with a helical wavefront at harmonic frequencies(e.g.,second and third harmonics). It provides an additional degree of freedom beyond spin-and orbitalangular momentum, which may greatly increase the capacity for communicating and encoding information. However, conventional harmonic vortex beam generators suffer from complex designs and a low nonlinear conversion efficiency. Here, we propose and experimentally demonstrate the generation of a large second-harmonic(SH) vortex beam with quasi-nonlinear spin–orbit interaction(SOI). Highquality SH vortex beams with large topological charges up to 28 are realized experimentally. This indicated that the quasi-angular-momentum of a plasmonic spiral phase plate at the excitation wavelength(topological charge, q) could be imprinted on the harmonic signals from the attached WS2 monolayer. The generated harmonic vortex beam has a topological charge of l_(n)= 2 nq(n is the harmonic order). The results may open new avenues for generating harmonic optical vortices for optical communications and enables novel multi-functional hybrid metasurface devices to manipulate harmonic beams.展开更多
文摘With the global promotion of LED lighting products, the health and safety of LED products has drawn wider attention. This paper systematically introduces the ergonomic evaluation (methods and indicators) svstem for heahh and comfort which differs from the traditional manpowered physical detection, and sketches out the evaluation indicators and its industrialization prospect.
文摘A laboratory-based work was conducted on development, biometry (cyst diameter, hatching efficiency and hatching percentage) and survival rate of Artemia franciscana at 35 ppt using natural brine water under constant aeration facilities. The experiment was carried out for both chorionic and decapsulated cysts. There was a significant increase in hatching output of the decapsulated cysts than the chorionic cysts. The survival rate was counted only for the chorionic cysts because nauplii hatched from decapsulated cysts died after four days of incubation before reaching the adult stage. Untill now the Artemia cysts are imported from abroad. Though the prospect of mass production of Artemia in Bangladesh is feasible but there needs to be more studies done.
文摘To some extent, college English teaching management affects the success or failure of university education. This paper analyzes the current status of research and management, the use of management to clarify the meaning of the five elements of law, based on the induction of the one-sided understanding, setting single, formal training, and simplistic assessment of the four questions, and start from the two elements of teaching and learning around how to teach, how to learn, how assessment of the problem, explore the three management initiatives, with a view of college English teaching management plays a certain significance.
基金the continuous supply of funds to the National Science and Technology Major Project-Developing Great Oil & Gas Field and Coal Bed Gas (No. 2008ZX05)
文摘Efforts to speed up China's coal bed methane (CBM) exploration developments related to production safety, optimization of energy structures, prevention of energy waste and reduction of greenhouse gas emissions are all of great significance. In order to strengthen CBM exploration and development in China and to encourage increased growth in the CBM industry, we firstly give a general overview of the recent technological innovations and other developments in CBM exploration in the U.S., Canada and other countries. Using this background information as the starting point, we further present observations and analyses of CBM exploration and development, preferential policies, technical support and implications of R&D for CBM development in China. The results show that the problems related to CBM exploration technology development and lack of a complete set of management policies are still the major issues slowing down the growth of domestic CBM industry. Development of resource exploration and technology, R&D and establishment of favorable government policy to support the industry and the creation of a relevant information platform, etc. are finally recommended.
基金Supported by the National Science and Technology Support Program Project (2006BAE03B06)
文摘ZrO2-MnO2-ZnO supports were prepared by the co-precipitation method,and then Ni-Na/ZrO2-MnO2-ZnO catalysts were prepared by the impregnation method.In this paper,the reactions to synthesize methyl isopropyl ketone and diethyl ketone by the one-step synthesis method over this catalyst were studied,and meanwhile,the impact of the catalyst preparation conditions and the reaction conditions on catalyst performance was also investigated.It was observed that under the conditions when Ni loading was 25%,calcination temperature was 400℃ and reduction temperature was 410℃,this catalyst had good catalytic performance on the reaction.The suitable reaction conditions were achieved:reaction temperature was 400℃;reaction at atmospheric pressure;liquid hourly space velocity of raw material of 0.5 h 1 ;and the molar ratio of(methanol)/(methyl ethyl ketone)/(water) was equal to 1/1/1.Under such conditions,the conversion of methyl ethyl ketone could achieve 41.7%,and the overall selectivity of methyl isopropyl ketone and diethyl ketone could achieve 83.3%,which was comparable to the conversion of 38.1% and the selectivity of 82.2% achieved by using palladium as the active material.The good stability made this catalyst have good prospects for industrial application.
文摘In recent years, with the rapid growth in demand for commercial launches, space institutions like NASA have been succeeded in the commercialization of aerospace services. According to the latest development trends on international commercial aerospace services and the current development status of domestic commercial aerospace services, suggestions on the development of China's commercial aerospace services based on policies, development modes and technical innovation are given.
文摘China is the only one country in the world with more than one hundred million people who aged over 60. With the dramatically increasing of population aging speed, the traditional endowment pattern with the element of family model has a weakening trend and does not satisfy the demand of urban elderly diversified and multi-level pension. Thus, pensions that occupy at home are becoming the best choice of the urban pension mode in China. The paper will describe the meaning, situation and prospects of the home endowment and demonstrate the significance of developing the home endowment project in China. Additionally, the paper will discuss the future endowment model from the aspects of the government organization, scientific planning and functional shifts.
文摘This article classifies the seawater desalination technology into four types of hot method, membrane method, electric field method and solvent method. Electric field method and solvent method still remain experimental stage, while hot method and membrane method have been realized in commercialization but are difficult to be promoted. The problem lies in high water-producing cost. It is difficult for membrane method seawater desalination technology to reduce the water-producing cost. The heat utilization efficiency is not high for the current hot method seawater desalination technology and there is large amount of heat lost with the emission of concentrated seawater. The new hot method seawater desalination technology and new solar-powered seawater desalination technology can divide the seawater into fresh water and solid salt without any emission of concentrated seawater so that the heat utilization efficiency can reach theoretical limit to multiply reduce the water-producing cost. They will become the mainstream technology for seawater desalination and can totally eliminate the global water crisis.
基金supported by the National Natural Science Foundation of China(Grant Nos.5132301151306145&51236007)
文摘Energy conversion and utilization, particularly carbon-based fuel burning in air phase, have caused great environmental pollution and serious problems to society. The reactions in water phase may have the potential to realize clean and efficient energy conversion and utilization. Coal gasification in supercritical water is a typical carbon-based fuel conversion process in water phase, and it takes the advantages of the unique chemical and physical properties of supercritical water to convert organic matter in coal to H2 and CO2. N, S, P, Hg and other elements are deposited as inorganic salts to avoid pollution emission. The State Key Laboratory of Multiphase Flow in Power Engineering has obtained extensive experimental and theoretical results based on coal gasification in supercritical water. Supercritical water fluidized bed reactor was developed for coal gasification and seven kinds of typical feedstock were selected. The hydrogen yield covers from 0.67 to 1.74 Nm3/kg and the carbon gasification efficiency is no less than 97%. This technology has a bright future in industrialization not only in electricity generation but also in hydrogen production and high value-added chemicals. Given the gas yield obtained in laboratory-scale unit, the hydrogen production cost is U.S.$ 0.111 Nm3 when the throughput capacity is 2000 t/d. A novel thermodynamic cycle power generation system based on coal gasification in supercritical water was proposed with the obvious advantages of high coal-electricity conversion efficiency and zero pollutant emission. The cost of U.S.$ 3.69 billion for desulfuration, denitration and dust removal in China in 2013 would have been saved with this technology. Five kinds of heat supply methods are analyzed and the rates of return of investment are roughly estimated. An integrated cooperative innovation center called a new type of high-efficient coal gasification technology and its large-scale utilization was founded to enhance the industrialization of the technology vigorously.
基金supported by U.S. National Science Foundation Grants (Grant Nos. 02-07886, and 01-25925)National Natural Science Foundation of China (Grant Nos. 91014002, 40821061)Ministry of Education of China (Grant No. B07039)
文摘Much has been learned in the past 40 years about the great diversity of the internal structure and geochemical compositions of Phanerozoic ophiolites, indicating that these on-land fragments of ancient oceanic lithosphere formed in distinctly different tectonic settings during their igneous evolution. Recent studies in Archean and Proterozoic greenstone belts have shown that the Precambrian rock record may also include exposures of a diverse suite of ophiolite complexes as part of craton development in the early history of the Earth. We review the salient features of the Precambrian ophiolite record to highlight what has been learned about Precambrian oceanic spreading systems since the original Penrose definition of ophiolites in 1972. Some of the diagnostic, characteristic, typical, and rare aspects of ophiolites of all ages are presented in a table in order to help determine if tectonically deformed and metamophosed sequences in Precambrian shield areas may be considered as ophiolites. The results of this comparative study are important in that they enable researchers to more realistically characterize allochthonous mafic/ultramafic rock sequences as ophiolitic or non-ophiolitic. This approach is more deterministic in contrast to some other arbitrary classification schemes requiring three or four of the Penrose-style ophiolitic units to be present in the Precambrian record for a specific rock sequence to be considered ophiolitic. Once these tectonic fragments are recognized as remnants of ancient oceanic lithosphere, great progress shall be made in understanding early Earth history. We discuss the significance and implications of the Precambrian ophiolite record to constrain the mode and nature of the plate tectonics that operated in deep time.
基金This work was supported by the National Natural Science Foundation of China(91850113,11774115 and 11904271)the National Basic Research Program of China(2014CB921301)the Basic and Applied Basic Research Major Program of Guangdong Province(2019B030302003)。
文摘A harmonic vortex beam is a typical vector beam with a helical wavefront at harmonic frequencies(e.g.,second and third harmonics). It provides an additional degree of freedom beyond spin-and orbitalangular momentum, which may greatly increase the capacity for communicating and encoding information. However, conventional harmonic vortex beam generators suffer from complex designs and a low nonlinear conversion efficiency. Here, we propose and experimentally demonstrate the generation of a large second-harmonic(SH) vortex beam with quasi-nonlinear spin–orbit interaction(SOI). Highquality SH vortex beams with large topological charges up to 28 are realized experimentally. This indicated that the quasi-angular-momentum of a plasmonic spiral phase plate at the excitation wavelength(topological charge, q) could be imprinted on the harmonic signals from the attached WS2 monolayer. The generated harmonic vortex beam has a topological charge of l_(n)= 2 nq(n is the harmonic order). The results may open new avenues for generating harmonic optical vortices for optical communications and enables novel multi-functional hybrid metasurface devices to manipulate harmonic beams.