The influence of summer monsoon on tropical cyclone (TC) genesis over the Bay of Bengal (BoB) is explored using an empirical genesis potential (GP) index. The annual cycle of cyclogenesis frequency over the BoB shows ...The influence of summer monsoon on tropical cyclone (TC) genesis over the Bay of Bengal (BoB) is explored using an empirical genesis potential (GP) index. The annual cycle of cyclogenesis frequency over the BoB shows an asymmetric bimodal pattern with the maximum genesis number appearing in late October and the second largest in early May. The two peaks correspond to the withdrawal and onset of the BoB summer monsoon, respectively. The semimonthly GP index calculated without TC days over the BoB is consistent with TC genesis frequency, indicating that the index captures the monsoon-induced changes in the environment that are responsible for the seasonal variation of TC genesis frequency. Of the four environmental variables (i.e., low-level vorticity, mid-level relative humidity, potential intensity, and vertical wind shear) that enter into the GP index, the potential intensity makes the largest contribution to the bimodal distribution, followed by vertical wind shear due to small wind speed during the summer monsoon onset and withdrawal. The difference in TC genesis frequency between autumn and late spring is mainly owing to the relative humid-ity difference because a divergence (convergence) of horizontal moisture flux associated with cold dry northerlies (warm wet wester-lies) dominates the BoB in late spring (autumn).展开更多
The number concentrations in the radius range of 0.06 – 5 μm of aerosol particles and meteorological parameters were measured on board during a cruise in the South China Sea from August 25 to October 12, 2012. Effec...The number concentrations in the radius range of 0.06 – 5 μm of aerosol particles and meteorological parameters were measured on board during a cruise in the South China Sea from August 25 to October 12, 2012. Effective fluxes in the reference height of 10 m were estimated by steady state dry deposition method based on the observed data, and the influences of different air masses on flux were discussed in this paper. The number size distribution was characterized by a bimodal mode, with the average total number concentration of（1.50 ± 0.76）×10~3 cm^（-3）. The two mode radii were 0.099 μm and 0.886 μm, both of which were within the scope of accumulation mode. A typical daily average size distribution was compared with that measured in the Bay of Bengal. In the whole radius range, the number concentrations were in agreement with each other; the modes were more distinct in this study than that abtained in the Bay of Bengal. The size distribution of the fluxes was fitted with the sum of log-normal and power-law distribution. The impact of different air masses was mainly on flux magnitude, rather than the shape of spectral distribution. A semiempirical source function that is applicable in the radius range of 0.06 μm展开更多
The Present work reports the variability of the derived sound channel and its parameters （surface sound velocity, conjugate depth, SLD （Sonic Layer depth） and SOFAR（Sound Fixing and Ranging） depth） has been pres...The Present work reports the variability of the derived sound channel and its parameters （surface sound velocity, conjugate depth, SLD （Sonic Layer depth） and SOFAR（Sound Fixing and Ranging） depth） has been presented over the Bay of Bengal and Arabian Sea. We use World Ocean Atlas Annual data （2013） on temperature; salinity of North Indian Ocean （0°-25°N; 50°-95°E） and its bathymetry have been utilized for the present computation. The depth of the sound channel axis increases towards the northern latitudes in the Arabian Sea, while it decreases in the Bay of Bengal. Coming to the conjugate depth, it shows variation from 120-400 m in the Bay of Bengal and 50-320 m in the Arabian Sea. The range of SLD is varying between 20-40 m in the Bay of Bengal and 10-30 m in the Arabian Sea. The Bay of Bengal and the Arabian Sea have depth limited nature of the profile, i.e. surface sound speed exceeds the near bottom values. This has an important implication in the sound propagation in the SOFAR channel. Anticipated acoustic rays in an ocean with depth limited profile will propagate as surface refracted, bottom reflected （RBR） rays. As a result, the effective sound channel lies much below the sea surface.展开更多
One of the problems associated with loading a fully composite structure with joints is that the loads are not linear through the neutral axis of the structure but are collinear; this induces additional moment and crea...One of the problems associated with loading a fully composite structure with joints is that the loads are not linear through the neutral axis of the structure but are collinear; this induces additional moment and creates a load in the normal direction, which is typically a critical load because it can create delamination and can only be withstood if it is small. Another problem is that the structure is difficult to inspect using conventional methods because of limited accessibility. With fiber Bragg grating （FBG）, the problem can potentially be solved in structures with a stiffness mismatch. The model used to represent the problem above is a composite stiffened skin with two loading cases： tensile and three-point bending. Additionally, FBG is used to monitor and characterize the delamination caused by both loading cases. Finite element modeling （FEM） with traction versus separation theory is performed to determine the critical area on the specimen for placement of the FBG before manufacturing and testing. In this research, FBG can successfully monitor and characterize delamination caused by both loading cases in structures that have mismatched stiffnesses. Also, FBG can predict the delamination growth quantitatively. A spectrum graph of the FBG results can be used to replace a conventional mechanical graph for use in structural health monitoring.展开更多
与他的明星同行们相比,2011年度普利兹克建筑奖(Pritzker Architectu re Prize)得主艾德瓦尔多·苏托·德·莫拉是典型的圈内闻名圈外无声的建筑师,自1980年创办自己的工作室以来,他已有六十多件作品建成,大部分都座落在他...与他的明星同行们相比,2011年度普利兹克建筑奖(Pritzker Architectu re Prize)得主艾德瓦尔多·苏托·德·莫拉是典型的圈内闻名圈外无声的建筑师,自1980年创办自己的工作室以来,他已有六十多件作品建成,大部分都座落在他的故乡葡萄牙。他擅长使用石材,其设计风格受到现代建筑大师密斯·凡·德罗(Mies Van Der Rohe)的影响,被称为"新密斯主义者"。展开更多
In this paper,a new type of multi-wavelength fiber laser is proposed and demonstrated experimentally.Superimposed fiber grating(SIFG) and chirp fiber Bragg grating(CFBG) are used for wavelength selection.Based on gain...In this paper,a new type of multi-wavelength fiber laser is proposed and demonstrated experimentally.Superimposed fiber grating(SIFG) and chirp fiber Bragg grating(CFBG) are used for wavelength selection.Based on gain equalization technology,by finely adjusting the stress device in the cavity,the gain and loss are equal,so as to suppress the modal competition and achieve multi-wavelength lasing at room temperature.The experimental results show that the laser can output stable multi-wavelength lasers simultaneously.The laser coupling loss is small,the structure is simple,and it is convenient for integration,so it can be widely used in dense wavelength division multiplexing(DWDM) system and optical fiber sensors.展开更多
基金supported by the National Basic Research Program of China(973Program:2012CB955604)National Natural Science Foundation of China(No.40975038,40830106)the CMA Program(GYHY200906008)
文摘The influence of summer monsoon on tropical cyclone (TC) genesis over the Bay of Bengal (BoB) is explored using an empirical genesis potential (GP) index. The annual cycle of cyclogenesis frequency over the BoB shows an asymmetric bimodal pattern with the maximum genesis number appearing in late October and the second largest in early May. The two peaks correspond to the withdrawal and onset of the BoB summer monsoon, respectively. The semimonthly GP index calculated without TC days over the BoB is consistent with TC genesis frequency, indicating that the index captures the monsoon-induced changes in the environment that are responsible for the seasonal variation of TC genesis frequency. Of the four environmental variables (i.e., low-level vorticity, mid-level relative humidity, potential intensity, and vertical wind shear) that enter into the GP index, the potential intensity makes the largest contribution to the bimodal distribution, followed by vertical wind shear due to small wind speed during the summer monsoon onset and withdrawal. The difference in TC genesis frequency between autumn and late spring is mainly owing to the relative humid-ity difference because a divergence (convergence) of horizontal moisture flux associated with cold dry northerlies (warm wet wester-lies) dominates the BoB in late spring (autumn).
基金supported by the National Natural Science Foundation of China under Grant NO.41276009
文摘The number concentrations in the radius range of 0.06 – 5 μm of aerosol particles and meteorological parameters were measured on board during a cruise in the South China Sea from August 25 to October 12, 2012. Effective fluxes in the reference height of 10 m were estimated by steady state dry deposition method based on the observed data, and the influences of different air masses on flux were discussed in this paper. The number size distribution was characterized by a bimodal mode, with the average total number concentration of（1.50 ± 0.76）×10~3 cm^（-3）. The two mode radii were 0.099 μm and 0.886 μm, both of which were within the scope of accumulation mode. A typical daily average size distribution was compared with that measured in the Bay of Bengal. In the whole radius range, the number concentrations were in agreement with each other; the modes were more distinct in this study than that abtained in the Bay of Bengal. The size distribution of the fluxes was fitted with the sum of log-normal and power-law distribution. The impact of different air masses was mainly on flux magnitude, rather than the shape of spectral distribution. A semiempirical source function that is applicable in the radius range of 0.06 μm
文摘The Present work reports the variability of the derived sound channel and its parameters （surface sound velocity, conjugate depth, SLD （Sonic Layer depth） and SOFAR（Sound Fixing and Ranging） depth） has been presented over the Bay of Bengal and Arabian Sea. We use World Ocean Atlas Annual data （2013） on temperature; salinity of North Indian Ocean （0°-25°N; 50°-95°E） and its bathymetry have been utilized for the present computation. The depth of the sound channel axis increases towards the northern latitudes in the Arabian Sea, while it decreases in the Bay of Bengal. Coming to the conjugate depth, it shows variation from 120-400 m in the Bay of Bengal and 50-320 m in the Arabian Sea. The range of SLD is varying between 20-40 m in the Bay of Bengal and 10-30 m in the Arabian Sea. The Bay of Bengal and the Arabian Sea have depth limited nature of the profile, i.e. surface sound speed exceeds the near bottom values. This has an important implication in the sound propagation in the SOFAR channel. Anticipated acoustic rays in an ocean with depth limited profile will propagate as surface refracted, bottom reflected （RBR） rays. As a result, the effective sound channel lies much below the sea surface.
文摘One of the problems associated with loading a fully composite structure with joints is that the loads are not linear through the neutral axis of the structure but are collinear; this induces additional moment and creates a load in the normal direction, which is typically a critical load because it can create delamination and can only be withstood if it is small. Another problem is that the structure is difficult to inspect using conventional methods because of limited accessibility. With fiber Bragg grating （FBG）, the problem can potentially be solved in structures with a stiffness mismatch. The model used to represent the problem above is a composite stiffened skin with two loading cases： tensile and three-point bending. Additionally, FBG is used to monitor and characterize the delamination caused by both loading cases. Finite element modeling （FEM） with traction versus separation theory is performed to determine the critical area on the specimen for placement of the FBG before manufacturing and testing. In this research, FBG can successfully monitor and characterize delamination caused by both loading cases in structures that have mismatched stiffnesses. Also, FBG can predict the delamination growth quantitatively. A spectrum graph of the FBG results can be used to replace a conventional mechanical graph for use in structural health monitoring.
文摘与他的明星同行们相比,2011年度普利兹克建筑奖(Pritzker Architectu re Prize)得主艾德瓦尔多·苏托·德·莫拉是典型的圈内闻名圈外无声的建筑师,自1980年创办自己的工作室以来,他已有六十多件作品建成,大部分都座落在他的故乡葡萄牙。他擅长使用石材,其设计风格受到现代建筑大师密斯·凡·德罗(Mies Van Der Rohe)的影响,被称为"新密斯主义者"。
基金supported by the National Natural Science Foundation of China(Nos.61205068 and 61475133)the Natural Science Foundation of Hebei Province(No.F2015203270)+1 种基金the Science and Technology Program of Hebei Province(Nos.4273301D,13210409 and 15273304D)the College Youth Talent Project of Hebei Province(No.BJ2014057)
文摘In this paper,a new type of multi-wavelength fiber laser is proposed and demonstrated experimentally.Superimposed fiber grating(SIFG) and chirp fiber Bragg grating(CFBG) are used for wavelength selection.Based on gain equalization technology,by finely adjusting the stress device in the cavity,the gain and loss are equal,so as to suppress the modal competition and achieve multi-wavelength lasing at room temperature.The experimental results show that the laser can output stable multi-wavelength lasers simultaneously.The laser coupling loss is small,the structure is simple,and it is convenient for integration,so it can be widely used in dense wavelength division multiplexing(DWDM) system and optical fiber sensors.
