We study the dynamical evolution of cold atoms in crossed optical dipole trap theoretically and experimentally. The atomic transport process is accompanied by two competitive kinds of physical mechanics, atomic loadin...We study the dynamical evolution of cold atoms in crossed optical dipole trap theoretically and experimentally. The atomic transport process is accompanied by two competitive kinds of physical mechanics, atomic loading and atomic loss.The loading process normally is negligible in the evaporative cooling experiment on the ground, while it is significant in preparation of ultra-cold atoms in the space station. Normally, the atomic loading process is much weaker than the atomic loss process, and the atomic number in the central region of the trap decreases monotonically, as reported in previous research. However, when the atomic loading process is comparable to the atomic loss process, the atomic number in the central region of the trap will initially increase to a maximum value and then slowly decrease, and we have observed the phenomenon first. The increase of atomic number in the central region of the trap shows the presence of the loading process, and this will be significant especially under microgravity conditions. We build a theoretical model to analyze the competitive relationship, which coincides with the experimental results well. Furthermore, we have also given the predicted evolutionary behaviors under different conditions. This research provides a solid foundation for further understanding of the atomic transport process in traps. The analysis of loading process is of significant importance for preparation of ultra-cold atoms in a crossed optical dipole trap under microgravity conditions.展开更多
Cross-shelf transport is important due to its role in the transport of nutrients, larvae, sediments, and pollutants. The role of coastal trapped waves(CTWs) and their contribution to the cross-shelf transport is prese...Cross-shelf transport is important due to its role in the transport of nutrients, larvae, sediments, and pollutants. The role of coastal trapped waves(CTWs) and their contribution to the cross-shelf transport is presently unknown. The impact of wind-driven CTWs on the structure of the cross-shelf currents and transport is investigated in the East China Sea(ECS) starting from theory. The cross-shelf currents are divided into four terms: the geostrophic balance(GB) term, the second-order wave(SOW) term, the bottom friction(BF) term and Ekman(EK) term, as well as three modes: the Kelvin wave(KW) mode, the first shelf wave(SW1) mode and the second shelf wave(SW2) mode. Comparison among these decompositions shows that(1) for the four terms, the effect of the GB and EK terms is continual, while that of the BF term is confi ned to 60–240 km of fshore, and the contribution of the SOW term can be ignored;(2) for the three modes, the KW and SW1 modes are dominant in cross-shelf transport. The results show that the total cross-shelf transport travels onshore under idealized wind stress on the order of 10^(-1), and it increases along the cross-shelf direction and peaks about-0.73 Sv at the continental shelf margin. With the increase of linear bottom friction coeffi cient, the cross-shelf transport declines with distance with the slope becoming more uniform.展开更多
Identification and counting of rice light-trap pests are important to monitor rice pest population dynamics and make pest forecast. Identification and counting of rice light-trap pests manually is time-consuming, and ...Identification and counting of rice light-trap pests are important to monitor rice pest population dynamics and make pest forecast. Identification and counting of rice light-trap pests manually is time-consuming, and leads to fatigue and an increase in the error rate. A rice light-trap insect imaging system is developed to automate rice pest identification. This system can capture the top and bottom images of each insect by two cameras to obtain more image features. A method is proposed for removing the background by color difference of two images with pests and non-pests. 156 features including color, shape and texture features of each pest are extracted into an support vector machine （SVM） classifier with radial basis kernel function. The seven-fold cross-validation is used to improve the accurate rate of pest identification. Four species of Lepidoptera rice pests are tested and achieved 97.5% average accurate rate.展开更多
Supercontinuum spectrum generation in a dispersion-flattened and decreasing fiber with two orthogonally polarized pulses was simulated and calculated. The research results indicated that the supercontinuum spectrum ge...Supercontinuum spectrum generation in a dispersion-flattened and decreasing fiber with two orthogonally polarized pulses was simulated and calculated. The research results indicated that the supercontinuum spectrum generated by two orthogonally polarized pulses is wider and flatter than that generated by single polarized pulse due to cross-phase modulation. The cross-phase modulation effect can enhance the supercontinuum spectrum generation. When the pump power of the input pulse is lower, the enhancement of supercontinuum spectrum generation by cross-phase modulation effect is more significant.展开更多
Nowadays,more than 50%of the world population live in middle-income economies.Economies in the middle-income development stage are confronted with a number of challenges,such as economic restructuring,industrial upgra...Nowadays,more than 50%of the world population live in middle-income economies.Economies in the middle-income development stage are confronted with a number of challenges,such as economic restructuring,industrial upgrade and income growth.Therefore,academia around the world have paid much attention to theoretical and empirical researches of the "middle income trap " and long-term trends of global economic growth.Based on analyses about the long-term growth path of the world economy and the characteristics of different stages of economic development,this paper defines the "middle income trap" and its characteristics and examines,through a large number of cases from different economies,the reasons why "growth slowdown " arises during the middle-income development stage.These theoretic and empirical researches have reference value and heuristic meaning for China to actively respond to the challenges of the "middle income trap ".展开更多
Through review of relevant studies and analysis, this article indicates that the ＂middleincome trap ＂ is in line with the framework of the mainstream economic growth theories, and, therefore, it is a useful concept ...Through review of relevant studies and analysis, this article indicates that the ＂middleincome trap ＂ is in line with the framework of the mainstream economic growth theories, and, therefore, it is a useful concept through which we can analyze economic growth phenomena in specific economic growth phases. The empirical experiences of many countries also indicate that at specific middle-income stages, economies with high rates of growth tend to encounter economic slowdown or even stagnation. The article shows that China is facing the challenge of determining how to move smoothly beyond the middle-income stage of economic development, while taking into account the shifting population structure, changing resource endowment and growth patterns. The article, drawing on international experiences, puts forward several policy suggestions relating to improvement in total factor productivity, expansion of human capital accumulation and deepening of system and governmentfunction reforms.展开更多
The news China surpassed Japan as the world’s second largest economy in 2010 has put China in the limelight. China’s per-capita GDP has reached $4,000, turning the country from a lower middle-income country to an up...The news China surpassed Japan as the world’s second largest economy in 2010 has put China in the limelight. China’s per-capita GDP has reached $4,000, turning the country from a lower middle-income country to an upper middle-income country. But the economic growth model is still extensive and the income gap between the rich and the poor is widening.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.92365208,11934002,and 11920101004)the National Key Research and Development Program of China(Grant Nos.2021YFA0718300 and 2021YFA1400900)+1 种基金the Science and Technology Major Project of Shanxi(Grant No.202101030201022)the Space Application System of China Manned Space Program。
文摘We study the dynamical evolution of cold atoms in crossed optical dipole trap theoretically and experimentally. The atomic transport process is accompanied by two competitive kinds of physical mechanics, atomic loading and atomic loss.The loading process normally is negligible in the evaporative cooling experiment on the ground, while it is significant in preparation of ultra-cold atoms in the space station. Normally, the atomic loading process is much weaker than the atomic loss process, and the atomic number in the central region of the trap decreases monotonically, as reported in previous research. However, when the atomic loading process is comparable to the atomic loss process, the atomic number in the central region of the trap will initially increase to a maximum value and then slowly decrease, and we have observed the phenomenon first. The increase of atomic number in the central region of the trap shows the presence of the loading process, and this will be significant especially under microgravity conditions. We build a theoretical model to analyze the competitive relationship, which coincides with the experimental results well. Furthermore, we have also given the predicted evolutionary behaviors under different conditions. This research provides a solid foundation for further understanding of the atomic transport process in traps. The analysis of loading process is of significant importance for preparation of ultra-cold atoms in a crossed optical dipole trap under microgravity conditions.
基金Supported by the National Natural Science Foundation of China(Nos.41476022,41506044)the Program for Innovation Research and Entrepreneurship Team in Jiangsu Province+1 种基金the National Program on Global Change and Air-Sea Interaction(No.GASI-IPOVAI-05)the Startup Foundation for Introducing Talent of Nanjing University of Information Science and Technology(Nos.2013r121,2014r072)
文摘Cross-shelf transport is important due to its role in the transport of nutrients, larvae, sediments, and pollutants. The role of coastal trapped waves(CTWs) and their contribution to the cross-shelf transport is presently unknown. The impact of wind-driven CTWs on the structure of the cross-shelf currents and transport is investigated in the East China Sea(ECS) starting from theory. The cross-shelf currents are divided into four terms: the geostrophic balance(GB) term, the second-order wave(SOW) term, the bottom friction(BF) term and Ekman(EK) term, as well as three modes: the Kelvin wave(KW) mode, the first shelf wave(SW1) mode and the second shelf wave(SW2) mode. Comparison among these decompositions shows that(1) for the four terms, the effect of the GB and EK terms is continual, while that of the BF term is confi ned to 60–240 km of fshore, and the contribution of the SOW term can be ignored;(2) for the three modes, the KW and SW1 modes are dominant in cross-shelf transport. The results show that the total cross-shelf transport travels onshore under idealized wind stress on the order of 10^(-1), and it increases along the cross-shelf direction and peaks about-0.73 Sv at the continental shelf margin. With the increase of linear bottom friction coeffi cient, the cross-shelf transport declines with distance with the slope becoming more uniform.
基金support of the National Natural Science Foundation of China (31071678)the Major Scientific and Technological Special of Zhejiang Province, China (2010C12026)+1 种基金the Ningbo Science and Technology Project, China (201002C1011001)Xiangshan Science and Technology Project, China(2010C0001)
文摘Identification and counting of rice light-trap pests are important to monitor rice pest population dynamics and make pest forecast. Identification and counting of rice light-trap pests manually is time-consuming, and leads to fatigue and an increase in the error rate. A rice light-trap insect imaging system is developed to automate rice pest identification. This system can capture the top and bottom images of each insect by two cameras to obtain more image features. A method is proposed for removing the background by color difference of two images with pests and non-pests. 156 features including color, shape and texture features of each pest are extracted into an support vector machine （SVM） classifier with radial basis kernel function. The seven-fold cross-validation is used to improve the accurate rate of pest identification. Four species of Lepidoptera rice pests are tested and achieved 97.5% average accurate rate.
基金Excellent Teacher Foundation of Guangdong Province(Q02084) Natural Science Foundation of Guangdong Province(04010397)
文摘Supercontinuum spectrum generation in a dispersion-flattened and decreasing fiber with two orthogonally polarized pulses was simulated and calculated. The research results indicated that the supercontinuum spectrum generated by two orthogonally polarized pulses is wider and flatter than that generated by single polarized pulse due to cross-phase modulation. The cross-phase modulation effect can enhance the supercontinuum spectrum generation. When the pump power of the input pulse is lower, the enhancement of supercontinuum spectrum generation by cross-phase modulation effect is more significant.
文摘Nowadays,more than 50%of the world population live in middle-income economies.Economies in the middle-income development stage are confronted with a number of challenges,such as economic restructuring,industrial upgrade and income growth.Therefore,academia around the world have paid much attention to theoretical and empirical researches of the "middle income trap " and long-term trends of global economic growth.Based on analyses about the long-term growth path of the world economy and the characteristics of different stages of economic development,this paper defines the "middle income trap" and its characteristics and examines,through a large number of cases from different economies,the reasons why "growth slowdown " arises during the middle-income development stage.These theoretic and empirical researches have reference value and heuristic meaning for China to actively respond to the challenges of the "middle income trap ".
文摘Through review of relevant studies and analysis, this article indicates that the ＂middleincome trap ＂ is in line with the framework of the mainstream economic growth theories, and, therefore, it is a useful concept through which we can analyze economic growth phenomena in specific economic growth phases. The empirical experiences of many countries also indicate that at specific middle-income stages, economies with high rates of growth tend to encounter economic slowdown or even stagnation. The article shows that China is facing the challenge of determining how to move smoothly beyond the middle-income stage of economic development, while taking into account the shifting population structure, changing resource endowment and growth patterns. The article, drawing on international experiences, puts forward several policy suggestions relating to improvement in total factor productivity, expansion of human capital accumulation and deepening of system and governmentfunction reforms.
文摘The news China surpassed Japan as the world’s second largest economy in 2010 has put China in the limelight. China’s per-capita GDP has reached $4,000, turning the country from a lower middle-income country to an upper middle-income country. But the economic growth model is still extensive and the income gap between the rich and the poor is widening.
