The similarity transformation model between different coordinate systems is not accurate enough to describe the discrepancy of them.Therefore,the coordinate transformation from the coordinate frame with poor accuracy ...The similarity transformation model between different coordinate systems is not accurate enough to describe the discrepancy of them.Therefore,the coordinate transformation from the coordinate frame with poor accuracy to that with high accuracy cannot guarantee a high precision of transformation.In this paper,a combined method of similarity transformation and regressive approximating is presented.The local error accumulation and distortion are taken into consideration and the precision of coordinate system is improved by using the recommended method展开更多
For the linear crack skeleton of railway bridges with irregular strike,it is difficult to accurately express the crack contour feature by using a single smoothing fitting algorithm.In order to improve the measurement ...For the linear crack skeleton of railway bridges with irregular strike,it is difficult to accurately express the crack contour feature by using a single smoothing fitting algorithm.In order to improve the measurement accuracy,a polynomial curve fitting was proposed,which used the calibration point of crack contour as the boundary point,and then put them all together to produce a continuous contour curve to achieve the crack length measurement.The method was tested by measuring the linar cracks with different shapes.It is shown that this proposed algorithm can not only solve the jagged problem generated in the crack skeleton extraction process,but also improve the crack length measurement accuracy.The relative deviation is less than 0.15,and the measurement accuracy is over 98.05%,which provides a more effective means for the crack length measurement in railway bridges.展开更多
This paper presents equations for estimating limiting stand density for Z undulata plantations grown in hot desert areas of Raj asthan State in India. Five different stand level basal area projection models, belonging...This paper presents equations for estimating limiting stand density for Z undulata plantations grown in hot desert areas of Raj asthan State in India. Five different stand level basal area projection models, belonging to the path invariant algebraic difference form of a non-linear growth function, were also tested and compared. These models can be used to predict future basal area as a function of stand variables like dominant height and stem number per hectare and are necessary for reviewing different silvicultural treatment options. Data from 22 sample plots were used for modelling. An all possible growth intervals data structure was used. Both, qualitative and quantitative criteria were used to compare alternative models. The Akaike＇s information criteria differ- ence statistic was used to analyze the predictive ability of the models. Results show that the model proposed by Hui and Gadow performed best and hence this model is recommended for use in predicting basal area development in 12 undulata plantations in the study area. The data used were not from thinned stands, and hence the models may be less accurate when used for predictions when natural mortality is very significant.展开更多
An 8 weeks feeding experiment was conducted to determine the effect of dietary potassium on the growth and physio-logical acclimation of Pacific white shrimp （Litopenaeus vannamei） reared in diluted seawater （salin...An 8 weeks feeding experiment was conducted to determine the effect of dietary potassium on the growth and physio-logical acclimation of Pacific white shrimp （Litopenaeus vannamei） reared in diluted seawater （salinity 4）. Six semi-purified practical diets containing 0.59, 0.96, 1.26, 1.48, 1.74, and 2.17 g potassium K＋ per 100 g diet were formulated, respectively. The survival and feed conversion rate did not show significant difference among groups of shrimps given these diets （P〉0.05）. The shrimps fed the diets containing 0.96-1.48 g K＋ per 100g diet gained the highest weight, specific growth rate, and protein efficiency ratio. Their ammonium-N excretion rate as well as hemolymph concentration of Na＋ and C1- were significantly lower than those of the control （P〈0.05）, but a reverse trend was observed for their gill Na＋/K＋-ATPase. Moreover, the shrimps fed with 1.48 g K＋ per 100 g diet were the highest in hemolymph urea level, and the phenoloxidase and lysozyme activities were significantly higher than those of the control （P〈0.05）. The growth and physiological response of the test shrimps suggested that diet containing 1.48 g K＋ per 100 g diet improved the growth of L. vannamei in low-salinity seawater, and enhanced the physiological acclimation of the organism.展开更多
Objective： To assess the correlation between five anthropometric parameters and the distance from tibial tuberosity to medial malleolus in 100 volunteers. Methods： Six anthropometric parameters were measured in 50 m...Objective： To assess the correlation between five anthropometric parameters and the distance from tibial tuberosity to medial malleolus in 100 volunteers. Methods： Six anthropometric parameters were measured in 50 male and 50 female medical students using a metallic scale： medial knee joint line to ankle joint line （K-A）, medial knee joint line to medial malleolus （K-MM）, tibial tuberosity to ankle joint （TT-A）, tibial tuberosity to medial malleolus （TT- MM）, olecranon to 5th metacarpal head （O-MH） and body height （BH）. Nail size predicted based upon Tr-MM measurement was chosen as ideal nail size. A constant was derived for each of the six anthropometric parameters which was either added or subtracted to each measurement to derive nail size. A regression equation was applied to BH measurements. Nail sizes calculated were compared with that obtained from TI＇-MM measurement and accuracy was evaluated. Accuracy of O-MH and BH regression equations recommended by other authors were calculated in our data. Results： Adding 11 mm to Tr-A distance had highest accuracy （81%） and correlation （0.966） in predicting nails correctly. Subtracting 33 mm from K-MM measurement and 25 mm from K-A distance derived accurate sizes in 69% and 76% respectively. Adding 6 mm to O-MH distance had a poor accuracy of 51%. Nail size prediction based upon body height regression equation derived correct nail sizes in only 34% of the cases. Regression equation analysis by other authors based on O-MH and BH distances yielded correct sizes in 11% and 5% of the cases respectively. Conclusion： TT-A, K-A and K-MM measurements can be used simultaneously to increase accuracy of nail size prediction. This method would be helpful in determining nail size preoperatively especially when one anatomic landmark is difficult to palpate.展开更多
High-precision sensing of vectorial forces has broad impact on both fundamental research and technological applications such as the examination of vacuum fluctuations and the detection of surface roughness of nanostru...High-precision sensing of vectorial forces has broad impact on both fundamental research and technological applications such as the examination of vacuum fluctuations and the detection of surface roughness of nanostructures.Recent years have witnessed much progress on sensing alternating electromagnetic forces for the rapidly advancing quantum technology-orders of magnitude improvement has been accomplished on the detection sensitivity with atomic sensors,whereas such high-precision measurements for static electromagnetic forces have rarely been demonstrated.Here,based on quantum atomic matter waves confined by a two-dimensional optical lattice,we perform precision measurement of static electromagnetic forces by imaging coherent wave mechanics in the reciprocal space.The lattice confinement causes a decoupling between real-space and reciprocal dynamics,and provides a rigid coordinate frame for calibrating the wavevector accumulation of the matter wave.With that we achieve a stateof-the-art sensitivity of 2.30(8)×10^(-26) N/√Hz.Long-term stabilities on the order of 10^(-28) N are observed in the two spatial components of a force,which allows probing atomic Van der Waals forces at one millimeter distance.As a further illustrative application,we use our atomic sensor to calibrate the control precision of an alternating electromagnetic force applied in the experiment.Future developments of this method hold promise for delivering unprecedented atom-based quantum force sensing technologies.展开更多
Nitrogen(N)deposition,precipitation and their interaction affect plant invasions in temperate ecosystems with limiting N and water resources,but whether and how they affect plant invasions in subtropical native commun...Nitrogen(N)deposition,precipitation and their interaction affect plant invasions in temperate ecosystems with limiting N and water resources,but whether and how they affect plant invasions in subtropical native communities with abundant N and precipitation remains unclear.We constructed in situ artificial communities with 12 common native plant species in a subtropical system and introduced four common invasive plant species and their native counterparts to these communities.We compared plant growth and establishment of introduced invasive species and native counterparts in communities exposed to ambient(CK),N addition(N+),increased precipitation(P+)and N addition plus increased precipitation(P+N+).We also investigated the density and aboveground biomass of communities under such conditions.P+alone did not enhance the performance of invasive species or native counterparts.N+enhanced only the aboveground biomass and relative density of invasive species.P+N+enhanced the growth and establishment performance of both invasive species and native counterparts.Most growth and establishment parameters of invasive species were greater than those of native counterparts under N+,P+and P+N+conditions.The density and aboveground biomass of native communities established by invasive species were significantly lower than those of native communities established by native counterparts under P+N+conditions.These results suggest that P+may magnify the effects of N+on performance of invasive species in subtropical native communities where N and water are often abundant,which may help to understand the effect of global change on plant invasion in subtropical ecosystems.展开更多
In this article, we apply the Generalized Uncertainty Principle （GUP）, which is consistent with quantum gravity theories to an elementary particle in a finite potential well, and study the quantum behavior in this s...In this article, we apply the Generalized Uncertainty Principle （GUP）, which is consistent with quantum gravity theories to an elementary particle in a finite potential well, and study the quantum behavior in this system. The generalized Hamiltonian contains two additional terms, which are proportional to ap3 （the result of the maximum momentum assumption） and a2p4 （the result of the minimum length assumption）, where a - 1/MpIc is the GUP parameter. On the basis of the work by Ali et al., we solve the generaiized Schrodinger equation which is extended to include the a2 correction term, and find that the length L of the finite potentiai well must be quantized. Then a generalization to the double-square-well potential is discussed. The result shows that all the measurable lengths especially the distance between the two potential wells are quantized in units of aolp1 in GUP scenario.展开更多
文摘The similarity transformation model between different coordinate systems is not accurate enough to describe the discrepancy of them.Therefore,the coordinate transformation from the coordinate frame with poor accuracy to that with high accuracy cannot guarantee a high precision of transformation.In this paper,a combined method of similarity transformation and regressive approximating is presented.The local error accumulation and distortion are taken into consideration and the precision of coordinate system is improved by using the recommended method
基金National Defense Pre-Research Fund Project(No.060601)Wanqiao Education Fund Project(No.06010023)。
文摘For the linear crack skeleton of railway bridges with irregular strike,it is difficult to accurately express the crack contour feature by using a single smoothing fitting algorithm.In order to improve the measurement accuracy,a polynomial curve fitting was proposed,which used the calibration point of crack contour as the boundary point,and then put them all together to produce a continuous contour curve to achieve the crack length measurement.The method was tested by measuring the linar cracks with different shapes.It is shown that this proposed algorithm can not only solve the jagged problem generated in the crack skeleton extraction process,but also improve the crack length measurement accuracy.The relative deviation is less than 0.15,and the measurement accuracy is over 98.05%,which provides a more effective means for the crack length measurement in railway bridges.
基金the State Forest Department,Rajasthan for providing financial support for conducting this study and to their officials for rendering necessary assistance during fieldwork
文摘This paper presents equations for estimating limiting stand density for Z undulata plantations grown in hot desert areas of Raj asthan State in India. Five different stand level basal area projection models, belonging to the path invariant algebraic difference form of a non-linear growth function, were also tested and compared. These models can be used to predict future basal area as a function of stand variables like dominant height and stem number per hectare and are necessary for reviewing different silvicultural treatment options. Data from 22 sample plots were used for modelling. An all possible growth intervals data structure was used. Both, qualitative and quantitative criteria were used to compare alternative models. The Akaike＇s information criteria differ- ence statistic was used to analyze the predictive ability of the models. Results show that the model proposed by Hui and Gadow performed best and hence this model is recommended for use in predicting basal area development in 12 undulata plantations in the study area. The data used were not from thinned stands, and hence the models may be less accurate when used for predictions when natural mortality is very significant.
文摘An 8 weeks feeding experiment was conducted to determine the effect of dietary potassium on the growth and physio-logical acclimation of Pacific white shrimp （Litopenaeus vannamei） reared in diluted seawater （salinity 4）. Six semi-purified practical diets containing 0.59, 0.96, 1.26, 1.48, 1.74, and 2.17 g potassium K＋ per 100 g diet were formulated, respectively. The survival and feed conversion rate did not show significant difference among groups of shrimps given these diets （P〉0.05）. The shrimps fed the diets containing 0.96-1.48 g K＋ per 100g diet gained the highest weight, specific growth rate, and protein efficiency ratio. Their ammonium-N excretion rate as well as hemolymph concentration of Na＋ and C1- were significantly lower than those of the control （P〈0.05）, but a reverse trend was observed for their gill Na＋/K＋-ATPase. Moreover, the shrimps fed with 1.48 g K＋ per 100 g diet were the highest in hemolymph urea level, and the phenoloxidase and lysozyme activities were significantly higher than those of the control （P〈0.05）. The growth and physiological response of the test shrimps suggested that diet containing 1.48 g K＋ per 100 g diet improved the growth of L. vannamei in low-salinity seawater, and enhanced the physiological acclimation of the organism.
文摘Objective： To assess the correlation between five anthropometric parameters and the distance from tibial tuberosity to medial malleolus in 100 volunteers. Methods： Six anthropometric parameters were measured in 50 male and 50 female medical students using a metallic scale： medial knee joint line to ankle joint line （K-A）, medial knee joint line to medial malleolus （K-MM）, tibial tuberosity to ankle joint （TT-A）, tibial tuberosity to medial malleolus （TT- MM）, olecranon to 5th metacarpal head （O-MH） and body height （BH）. Nail size predicted based upon Tr-MM measurement was chosen as ideal nail size. A constant was derived for each of the six anthropometric parameters which was either added or subtracted to each measurement to derive nail size. A regression equation was applied to BH measurements. Nail sizes calculated were compared with that obtained from TI＇-MM measurement and accuracy was evaluated. Accuracy of O-MH and BH regression equations recommended by other authors were calculated in our data. Results： Adding 11 mm to Tr-A distance had highest accuracy （81%） and correlation （0.966） in predicting nails correctly. Subtracting 33 mm from K-MM measurement and 25 mm from K-A distance derived accurate sizes in 69% and 76% respectively. Adding 6 mm to O-MH distance had a poor accuracy of 51%. Nail size prediction based upon body height regression equation derived correct nail sizes in only 34% of the cases. Regression equation analysis by other authors based on O-MH and BH distances yielded correct sizes in 11% and 5% of the cases respectively. Conclusion： TT-A, K-A and K-MM measurements can be used simultaneously to increase accuracy of nail size prediction. This method would be helpful in determining nail size preoperatively especially when one anatomic landmark is difficult to palpate.
基金supported by the National Program on Key Basic Research Project of China (2018YFA0305601, 2021YFA07183012021YFA1400900)+4 种基金the National Natural Science Foundation of China (61727819, 11934002, and 11874073)Shanghai Municipal Science and Technology Major Project (2019SHZDZCX01)the Chinese Academy of Sciences Priority Research Program(XDB35020100)the Science and Technology Major Project of Shanxi (202101030201022)the Space Application System of China Manned Space Program
文摘High-precision sensing of vectorial forces has broad impact on both fundamental research and technological applications such as the examination of vacuum fluctuations and the detection of surface roughness of nanostructures.Recent years have witnessed much progress on sensing alternating electromagnetic forces for the rapidly advancing quantum technology-orders of magnitude improvement has been accomplished on the detection sensitivity with atomic sensors,whereas such high-precision measurements for static electromagnetic forces have rarely been demonstrated.Here,based on quantum atomic matter waves confined by a two-dimensional optical lattice,we perform precision measurement of static electromagnetic forces by imaging coherent wave mechanics in the reciprocal space.The lattice confinement causes a decoupling between real-space and reciprocal dynamics,and provides a rigid coordinate frame for calibrating the wavevector accumulation of the matter wave.With that we achieve a stateof-the-art sensitivity of 2.30(8)×10^(-26) N/√Hz.Long-term stabilities on the order of 10^(-28) N are observed in the two spatial components of a force,which allows probing atomic Van der Waals forces at one millimeter distance.As a further illustrative application,we use our atomic sensor to calibrate the control precision of an alternating electromagnetic force applied in the experiment.Future developments of this method hold promise for delivering unprecedented atom-based quantum force sensing technologies.
基金funded by the National Natural Science Foundation of China(31460165,31960282)Natural Science Foundation of Guangxi Province(2018GXNSFAA281112)Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain(19-050-6).
文摘Nitrogen(N)deposition,precipitation and their interaction affect plant invasions in temperate ecosystems with limiting N and water resources,but whether and how they affect plant invasions in subtropical native communities with abundant N and precipitation remains unclear.We constructed in situ artificial communities with 12 common native plant species in a subtropical system and introduced four common invasive plant species and their native counterparts to these communities.We compared plant growth and establishment of introduced invasive species and native counterparts in communities exposed to ambient(CK),N addition(N+),increased precipitation(P+)and N addition plus increased precipitation(P+N+).We also investigated the density and aboveground biomass of communities under such conditions.P+alone did not enhance the performance of invasive species or native counterparts.N+enhanced only the aboveground biomass and relative density of invasive species.P+N+enhanced the growth and establishment performance of both invasive species and native counterparts.Most growth and establishment parameters of invasive species were greater than those of native counterparts under N+,P+and P+N+conditions.The density and aboveground biomass of native communities established by invasive species were significantly lower than those of native communities established by native counterparts under P+N+conditions.These results suggest that P+may magnify the effects of N+on performance of invasive species in subtropical native communities where N and water are often abundant,which may help to understand the effect of global change on plant invasion in subtropical ecosystems.
基金Supported by National Natural Science Foundation of China under Grant Nos.10865003 and 11464005
文摘In this article, we apply the Generalized Uncertainty Principle （GUP）, which is consistent with quantum gravity theories to an elementary particle in a finite potential well, and study the quantum behavior in this system. The generalized Hamiltonian contains two additional terms, which are proportional to ap3 （the result of the maximum momentum assumption） and a2p4 （the result of the minimum length assumption）, where a - 1/MpIc is the GUP parameter. On the basis of the work by Ali et al., we solve the generaiized Schrodinger equation which is extended to include the a2 correction term, and find that the length L of the finite potentiai well must be quantized. Then a generalization to the double-square-well potential is discussed. The result shows that all the measurable lengths especially the distance between the two potential wells are quantized in units of aolp1 in GUP scenario.
