The Bowen ratio (B) is impacted by 5 environmental elements: soil moisture availabillity, m, the ratio of resistances between atmosphere and soil pores, atmospheric relative humidity, h,atmospheric stability, △T, an...The Bowen ratio (B) is impacted by 5 environmental elements: soil moisture availabillity, m, the ratio of resistances between atmosphere and soil pores, atmospheric relative humidity, h,atmospheric stability, △T, and enviD ronment temperature. These impacts have been investigated over diverse surfaces, including bare soil, free water surface, and vegetation covered land, using an analytical approach. It was concluded that: (a) B is not a continuous function. The singularity exists at the condition αhcb = h, occurring preferably in the following conditions f weak turbulence, stable stratified stability, dry soil, and humid air, where hcb, defined by Eq.(11) is a critical variable. The existence of a singularity makes the dependence of B on the five variables very complicated. The value of B approaches being inversely proportional to m under the conditions m≥mfc (the soil capacity) and / 0.The proportional coefficient changes with season and latitude with relatively high values in winter and over the poles; (b) B is nearly independent of during the day. The impact of m on B is much larger as compared to that of on B; (c) when h increases, the absolute value of B also increases; (d) over bare soil,when the absolute surface net radiation increases, the absolute value of B will increase. The impact of RN on B is larger at night than during the day, and (e) over plant canopy, the singularity and the dependdes of B on m,rα, and h are modified as compared to that over bare soil.Also (i) during the daytime unstable condition, m exerts an even stronger impact on B; at night, however,B changes are weak in response to the change in m; (ii) the value of B is much more sensitive in response to the changes of turbulent intensity; (iii) the B response to the variation of h over a vegetation covered area is weaker; and (iv) the singularity exists at the condition hcp=h instead of αhcb=h as over bare soil, where hcp is defined by Eq.(49). The formulas derived over bare soil also hold the same when applied to free water bodies as long as they are visualized as a special soil in which the volumetric fraction of soil pore is equal to one and are fully filled with water.Finally, the above discussions are used to briefly study the impact on the thermally induced mesoscale circulations.展开更多
The spatial distribution of physico-chemical parameters（sea surface temperature（SST）, p H, sea surface salinity（SSS）, dissolved oxygen（DO） and Secchi depth） along with filterable nutrients（dissolved inorganic...The spatial distribution of physico-chemical parameters（sea surface temperature（SST）, p H, sea surface salinity（SSS）, dissolved oxygen（DO） and Secchi depth） along with filterable nutrients（dissolved inorganic nitrate（DIN）,dissolved inorganic phosphate（DIP） and reactive silicate（DSi）） are measured in the winter months of November,December, January and February for four consecutive years from 2009–2010 to 2012–2013 on the shallow continental shelf（〈20 m bathymetry） of the coastal waters（up to 18 km away from shoreline） of the northern Bay of Bengal（n Bo B） during the highest high tide（HHT） and lowest low tide（LLT） hours for the first time. The variability of the coastal biogeochemical environment is assessed during the HHT and LLT hours and for this purpose, seawater samples are collected from seven different locations of a transect in the coastal region. Physicochemical parameters（except SST） show significant difference in magnitude during the HHT and LLT hours respectively. p H, SSS and DO are found to increase in the HHT hours and vice-versa. The data reveal that during the LLT hours, a relative increase of freshwater input in the n Bo B can have elevated the nutrient concentration compared with that observed during the HHT hours. The ratio of nutrient concentration is found to deviate significantly from the Redfield ratio. The abundance of DIP is much higher compared with that of DIN and DSi.The anthropogenic sources of DIP from the upstream flow（especially the domestic effluent of several metropolises） can be mainly attributed behind such an observation. In order to characterize and establish the trend of such variation in such an important bio-climatic region, long-term and systematic ecosystem monitoring in the coastal water of the n Bo B northern Bay of Bengal should be carried out throughout the year.展开更多
In order to improve the effectiveness of traditional time domain identification methods in identifying damping ratios, a new damping ratio identification method based on pattern search is proposed by fluctuating the r...In order to improve the effectiveness of traditional time domain identification methods in identifying damping ratios, a new damping ratio identification method based on pattern search is proposed by fluctuating the reliable natural frequency obtained through traditional time domain identification methods by about 10% to build the boundary conditions, using all the initial identification results to establish the free decay response of the system, and using the pattern search method to correct the initial identification results with the residual sum of squares between the free decay response and the actually measured free-decay signal as the objective function. The proposed method deals with the actually measured free-decay signal with curve fitting and avoids enlarging the identified error caused by intermediate conversion, so it can effectively improve the identified accuracy of damping ratios. Simulations for a room-sized vibration isolation foundation show that the relative errors of analyzed three damping ratios are down to 1.05%, 1.51% and 3.7% by the proposed method from 8.42%, 5.85% and 8.5% by STD method when the noise level is 10%.展开更多
This paper provides methods for assessing the precision of cost elasticity estimates when the underlying regression function is assumed to be polynomial. Specifically, the paper adapts two well-known methods for compu...This paper provides methods for assessing the precision of cost elasticity estimates when the underlying regression function is assumed to be polynomial. Specifically, the paper adapts two well-known methods for computing confidential intervals for ratios: the delta-method and the Fieller method. We show that performing the estimation with mean-centered explanatory variables provides a straightforward way to estimate the elasticity and compute a confidence interval for it. A theoretical discussion of the proposed methods is provided, as well as an empirical example based on publicly available postal data. Possible areas of application include postal service providers worldwide, transportation and electricity.展开更多
文摘The Bowen ratio (B) is impacted by 5 environmental elements: soil moisture availabillity, m, the ratio of resistances between atmosphere and soil pores, atmospheric relative humidity, h,atmospheric stability, △T, and enviD ronment temperature. These impacts have been investigated over diverse surfaces, including bare soil, free water surface, and vegetation covered land, using an analytical approach. It was concluded that: (a) B is not a continuous function. The singularity exists at the condition αhcb = h, occurring preferably in the following conditions f weak turbulence, stable stratified stability, dry soil, and humid air, where hcb, defined by Eq.(11) is a critical variable. The existence of a singularity makes the dependence of B on the five variables very complicated. The value of B approaches being inversely proportional to m under the conditions m≥mfc (the soil capacity) and / 0.The proportional coefficient changes with season and latitude with relatively high values in winter and over the poles; (b) B is nearly independent of during the day. The impact of m on B is much larger as compared to that of on B; (c) when h increases, the absolute value of B also increases; (d) over bare soil,when the absolute surface net radiation increases, the absolute value of B will increase. The impact of RN on B is larger at night than during the day, and (e) over plant canopy, the singularity and the dependdes of B on m,rα, and h are modified as compared to that over bare soil.Also (i) during the daytime unstable condition, m exerts an even stronger impact on B; at night, however,B changes are weak in response to the change in m; (ii) the value of B is much more sensitive in response to the changes of turbulent intensity; (iii) the B response to the variation of h over a vegetation covered area is weaker; and (iv) the singularity exists at the condition hcp=h instead of αhcb=h as over bare soil, where hcp is defined by Eq.(49). The formulas derived over bare soil also hold the same when applied to free water bodies as long as they are visualized as a special soil in which the volumetric fraction of soil pore is equal to one and are fully filled with water.Finally, the above discussions are used to briefly study the impact on the thermally induced mesoscale circulations.
基金Indian National Centre for Ocean Information Services(INCOIS)of the Ministry of Earth Science of Indiathe INSPIRE fellowship of Department of Science and Technology of India
文摘The spatial distribution of physico-chemical parameters（sea surface temperature（SST）, p H, sea surface salinity（SSS）, dissolved oxygen（DO） and Secchi depth） along with filterable nutrients（dissolved inorganic nitrate（DIN）,dissolved inorganic phosphate（DIP） and reactive silicate（DSi）） are measured in the winter months of November,December, January and February for four consecutive years from 2009–2010 to 2012–2013 on the shallow continental shelf（〈20 m bathymetry） of the coastal waters（up to 18 km away from shoreline） of the northern Bay of Bengal（n Bo B） during the highest high tide（HHT） and lowest low tide（LLT） hours for the first time. The variability of the coastal biogeochemical environment is assessed during the HHT and LLT hours and for this purpose, seawater samples are collected from seven different locations of a transect in the coastal region. Physicochemical parameters（except SST） show significant difference in magnitude during the HHT and LLT hours respectively. p H, SSS and DO are found to increase in the HHT hours and vice-versa. The data reveal that during the LLT hours, a relative increase of freshwater input in the n Bo B can have elevated the nutrient concentration compared with that observed during the HHT hours. The ratio of nutrient concentration is found to deviate significantly from the Redfield ratio. The abundance of DIP is much higher compared with that of DIN and DSi.The anthropogenic sources of DIP from the upstream flow（especially the domestic effluent of several metropolises） can be mainly attributed behind such an observation. In order to characterize and establish the trend of such variation in such an important bio-climatic region, long-term and systematic ecosystem monitoring in the coastal water of the n Bo B northern Bay of Bengal should be carried out throughout the year.
基金Sponsored by the National Natural Science Foundation of China (Grant No.50675052)
文摘In order to improve the effectiveness of traditional time domain identification methods in identifying damping ratios, a new damping ratio identification method based on pattern search is proposed by fluctuating the reliable natural frequency obtained through traditional time domain identification methods by about 10% to build the boundary conditions, using all the initial identification results to establish the free decay response of the system, and using the pattern search method to correct the initial identification results with the residual sum of squares between the free decay response and the actually measured free-decay signal as the objective function. The proposed method deals with the actually measured free-decay signal with curve fitting and avoids enlarging the identified error caused by intermediate conversion, so it can effectively improve the identified accuracy of damping ratios. Simulations for a room-sized vibration isolation foundation show that the relative errors of analyzed three damping ratios are down to 1.05%, 1.51% and 3.7% by the proposed method from 8.42%, 5.85% and 8.5% by STD method when the noise level is 10%.
文摘This paper provides methods for assessing the precision of cost elasticity estimates when the underlying regression function is assumed to be polynomial. Specifically, the paper adapts two well-known methods for computing confidential intervals for ratios: the delta-method and the Fieller method. We show that performing the estimation with mean-centered explanatory variables provides a straightforward way to estimate the elasticity and compute a confidence interval for it. A theoretical discussion of the proposed methods is provided, as well as an empirical example based on publicly available postal data. Possible areas of application include postal service providers worldwide, transportation and electricity.
