Liquid distributor is a very import intemal for distillation columns. Pre-distributor is usually set on the top of distributor for initial distribution. Fluid flow in pre-distributor is a complex system of variable ma...Liquid distributor is a very import intemal for distillation columns. Pre-distributor is usually set on the top of distributor for initial distribution. Fluid flow in pre-distributor is a complex system of variable mass flow with many orifices and sub-branches. Consequently, the two phase modeling of pre-distributors was carried out andthe homogeneous model with free surface model was applied. The numerical method was validated by comparing with experimental data. Using the simulated results for different pre-distributors, the impacts of inflow rate, location and orientation uoon the outflow distribution were investigated. Furthermore, influences of the outflow distribution for pre-distributor on liquid uniformity in trough were also analyzed, The conclusions can De aaoptea for me structural design of liquid distributor and pre-distributor of large scale.展开更多
The extreme temperature differences in fiat steel box girder of a cable-stayed bridge were studied.Firstly,by using the long-term measurement data collected by the structural health monitoring system installed on the ...The extreme temperature differences in fiat steel box girder of a cable-stayed bridge were studied.Firstly,by using the long-term measurement data collected by the structural health monitoring system installed on the Runyang Cable-stayed Bridge,the daily variations as well as seasonal ones of measured temperature differences in the box girder cross-section area were summarized.The probability distribution models of temperature differences were further established and the extreme temperature differences were estimated with a return period of 100 years.Finally,the temperature difference models in cross-section area were proposed for bridge thermal design.The results show that horizontal temperature differences in top plate and vertical temperature differences between top plate and bottom plate are considerable.All the positive and negative temperature differences can be described by the weighted sum of two Weibull distributions.The maximum positive and negative horizontal temperature differences in top plate are 10.30 ℃ and -13.80 ℃,respectively.And the maximum positive and negative vertical temperature differences between top plate and bottom plate are 17.30 ℃ and-3.70 ℃,respectively.For bridge thermal design,there are two vertical temperature difference models between top plate and bottom plate,and six horizontal temperature difference models in top plate.展开更多
Since the early 1990, significant progress in database technology has provided new platform for emerging new dimensions of data engineering. New models were introduced to utilize the data sets stored in the new genera...Since the early 1990, significant progress in database technology has provided new platform for emerging new dimensions of data engineering. New models were introduced to utilize the data sets stored in the new generations of databases. These models have a deep impact on evolving decision-support systems. But they suffer a variety of practical problems while accessing real-world data sources. Specifically a type of data storage model based on data distribution theory has been increasingly used in recent years by large-scale enterprises, while it is not compatible with existing decision-support models. This data storage model stores the data in different geographical sites where they are more regularly accessed. This leads to considerably less inter-site data transfer that can reduce data security issues in some circumstances and also significantly improve data manipulation transactions speed. The aim of this paper is to propose a new approach for supporting proactive decision-making that utilizes a workable data source management methodology. The new model can effectively organize and use complex data sources, even when they are distributed in different sites in a fragmented form. At the same time, the new model provides a very high level of intellectual management decision-support by intelligent use of the data collections through utilizing new smart methods in synthesizing useful knowledge. The results of an empirical study to evaluate the model are provided.展开更多
Soil moisture characteristic curve （SMC） is a fundamental soil property and its direct measurement is tedious and time consuming. Therefore, various indirect methods have been developed to predict SMC from particle-...Soil moisture characteristic curve （SMC） is a fundamental soil property and its direct measurement is tedious and time consuming. Therefore, various indirect methods have been developed to predict SMC from particle-size distribution （PSD）. However, the majority of these methods often yield intermittent SMC data because they involve estimating individual SMC points. The objectives of this study were 1） to develop a procedure to predict continuous SMC from a limited number of experimental PSD data points and 2） to evaluate model predictions through comparisons with measured values. In this study, an approach that allowed predicting SMC from the knowledge of PSD, parameterized by means of the closed-form van Genuchten model （VG）, was used. Through using Mohammadi and Vanclooster （MV） model, the parameters obtained from fitting of VG to PSD data were applied to predict SMC curves. Since the residual water content （Or） could not be obtained through fitting of VG-MV integrated model to PSD data, we also examined and compared four different methods estimating 0r. Results showed that the proposed equation （MV-VG integrated model） provided an excellent fit to all the PSD data and the model could adequately predict SMC as measured in forty-two soils sampled from different regions of Iran. For all soils, the method in which Or Was obtained through parameter optimization procedure provided the best overall predictions of SMC. The two methods estimating Or with Campbell and Shiozawa （CS） model resulted in less accuracy than the optimization procedure. Furthermore, the proposed model underestimated the moisture content in the dry range of SMC when the value of 0r was assumed to equal zero. 0r could be attributed to the incomplete desorption of water coated on soil particles and the accurate estimation of 0r was critical in prediction of SMC, especially for fine-textured soils at high suction heads. It could be concluded that the advantages of our approach were the continuity, robustness, and independency of model performance on soil type, allowing to improve predictions of SMC from PSD at the field and watershed scales.展开更多
Modeling the mean and covariance simultaneously is a common strategy to efficiently estimate the mean parameters when applying generalized estimating equation techniques to longitudinal data. In this article, using ge...Modeling the mean and covariance simultaneously is a common strategy to efficiently estimate the mean parameters when applying generalized estimating equation techniques to longitudinal data. In this article, using generalized estimation equation techniques, we propose a new kind of regression models for parameterizing covariance structures. Using a novel Cholesky factor, the entries in this decomposition have moving average and log innovation interpretation and are modeled as the regression coefficients in both the mean and the linear functions of covariates. The resulting estimators for eovarianee are shown to be consistent and asymptotically normally distributed. Simulation studies and a real data analysis show that the proposed approach yields highly efficient estimators for the parameters in the mean, and provides parsimonious estimation for the covariance structure.展开更多
Forests have long life cycles of up to several hundred years and longer.They also have very different growth rates at different stages of their life cycles.Therefore the carbon cycle in forest ecosystems has long time...Forests have long life cycles of up to several hundred years and longer.They also have very different growth rates at different stages of their life cycles.Therefore the carbon cycle in forest ecosystems has long time scales,making it necessary to consider forest age in estimating the spatiotemporal dynamics of carbon sinks in forests.The focus of this article is to review methods for combining recent remote sensing data with historical climate data for estimating the forest carbon source and sink distribution.Satellite remote sensing provides useful data for the land surface in recent decades. The information derived from remote sensing data can be used for short-term forest growth estimation and for mapping forest stand age for longterm simulations.For short-term forest growth estimation, remote sensing can provide forest structural parameters as inputs to process-based models,including big-leaf,two-leaf,and multi-layered models. These models use different strategies to upscale from leaf to canopy,and their reliability and suitability for remote sensing applications will be examined here.For long-term forest carbon cycle estimation, the spatial distribution of the forest growth rate（net primary productivity,NPP） modeled using remote sensing data in recent years is a critical input.This input can be combined with a forest age map to simulate the historical variation of NPP under the influence of climate and atmospheric changes. Another important component of the forest carbon cycle is heterotrophic respiration in the soil,which depends on the sizes of soil carbon pools as well as climate conditions.Methods for estimating the soil carbon spatial distribution and its separation into pools are described.The emphasis is placed on how to derive the soil carbon pools from NPP estimation in current years with consideration of forest carbon dynamics associated with stand age variation and climate and atmospheric changes.The role of disturbance in the forest carbon cycle and the effects of forest regrowth after disturbance are also considered in this review.An example of national forest carbon budget estimation in Canada is given at the end.It illustrates the importance of forest stand age structure in estimating the national forest carbon budgets and the effects of climate and atmospheric changes on the forest carbon cycle.展开更多
We study the centrality dependence of the mid-rapidity （｜y｜ 〈 0.5） yields and transverse momentum distributions of K＊ （892）° and φ（1020） resonances produced in Pb ＋ Pb collisions at SNN= 2.76 TeV. The...We study the centrality dependence of the mid-rapidity （｜y｜ 〈 0.5） yields and transverse momentum distributions of K＊ （892）° and φ（1020） resonances produced in Pb ＋ Pb collisions at SNN= 2.76 TeV. The mid- rapidity density （dN/dy） and the shape of the transverse momentum spectra are well reproduced by an earlier proposed Unified Statistical Thermal Freeze-out Model （USTFM）, which incorporates the effects of both longitudinal as well as transverse hydrodynamic flow. The freeze-out properties in terms of kinetic freeze-out temperature and transverse flow velocity parameter are extracted from the model fits to the transverse momentum data provided by the ALICE experiment at the LHC. The kinetic freeze-out temperature is found to increase with decreasing event centrality while the transverse flow velocity parameter shows a mild decrease on moving towards peripheral collisions. Moreover the centrality dependence of the mid-rapidity system size at freeze-out has also been studied in terms of transverse radius parameter.展开更多
The Daya Bay Reactor Neutrino Experiment is to measure the smallest mixing angle θ13.The experiment contains three major experiment halls,Daya Bay near site,Linao near site and far site,and two major kinds of detecto...The Daya Bay Reactor Neutrino Experiment is to measure the smallest mixing angle θ13.The experiment contains three major experiment halls,Daya Bay near site,Linao near site and far site,and two major kinds of detectors,antineutrino detector which is to detect the antineutrinos by the inverse beta-decay reaction in Gd-LS,and muon detector which is to study and reject cosmogenic backgrounds.The goal of the detector control system(DCS)is to operate and detect the detectors and keep them running in safety.In consideration of the limited fund of this system and manpower of working on this system,the LabVIEW is chosen to develop the detector control system.The architecture of DCS adopts the distributed data management which is based on client-server model.The server part is to detect and operate parameters from hardware,save data to database and release data to clients,the client is to receive data from the server.The detector control system contains three parts:the hardware part,the local control system and the global control part.The local control system includes high voltage supply system,low voltage supply system,VME crate system,temperature and humidity system,gas pressure system,and so on.展开更多
In this contribution, I identify possible biotic elements of reptiles of China using biotic element analysis. I test whether the vicariance model could significantly shape reptilian current distribution patterns. My r...In this contribution, I identify possible biotic elements of reptiles of China using biotic element analysis. I test whether the vicariance model could significantly shape reptilian current distribution patterns. My results show that dispersal is prevailing for reptiles in China. There are four major biotic elements in reptilian distribution, which are East Xizang, Yunnan- Guizhou Plateau, Taiwan and Hainan, respectively. The test of distributional areas is significantly more clustered than expected by chance, while in another test that closely related species are homogeneously distributed across biotic elements cannot be rejected. Therefore I argued that vicariance might be one of the key processes in patterning reptilian distribution in China. In addition, I develop an improved biotic element analysis in biogeographic studies, by performing biotic element analysis in an iterative man- ner in order to diagnose more geographically restricted elements until no noise components found. The importance of antecedent selection of distributional data for the subsequent analysis is also discussed. Besides, my study indicates that biodiversity hotspots are not fully overlapped with areas of endemism for reptilians in East Asia展开更多
基金Supported by the National Key Basic Research and Development Program of China (2009CB219905, 2009CB219907)the Program for Changjiang Scholars and Innovative Research Teams in Universities (IRT0936)
文摘Liquid distributor is a very import intemal for distillation columns. Pre-distributor is usually set on the top of distributor for initial distribution. Fluid flow in pre-distributor is a complex system of variable mass flow with many orifices and sub-branches. Consequently, the two phase modeling of pre-distributors was carried out andthe homogeneous model with free surface model was applied. The numerical method was validated by comparing with experimental data. Using the simulated results for different pre-distributors, the impacts of inflow rate, location and orientation uoon the outflow distribution were investigated. Furthermore, influences of the outflow distribution for pre-distributor on liquid uniformity in trough were also analyzed, The conclusions can De aaoptea for me structural design of liquid distributor and pre-distributor of large scale.
基金Project(51178100)supported by the National Natural Science Foundation of ChinaProject(1105007001)supported by the Foundation of the Priority Academic Development Program of Higher Education Institute of Jiangsu Province,ChinaProject(3205001205)supported by the Teaching and Research Foundation for Excellent Young Teachers of Southeast University,China
文摘The extreme temperature differences in fiat steel box girder of a cable-stayed bridge were studied.Firstly,by using the long-term measurement data collected by the structural health monitoring system installed on the Runyang Cable-stayed Bridge,the daily variations as well as seasonal ones of measured temperature differences in the box girder cross-section area were summarized.The probability distribution models of temperature differences were further established and the extreme temperature differences were estimated with a return period of 100 years.Finally,the temperature difference models in cross-section area were proposed for bridge thermal design.The results show that horizontal temperature differences in top plate and vertical temperature differences between top plate and bottom plate are considerable.All the positive and negative temperature differences can be described by the weighted sum of two Weibull distributions.The maximum positive and negative horizontal temperature differences in top plate are 10.30 ℃ and -13.80 ℃,respectively.And the maximum positive and negative vertical temperature differences between top plate and bottom plate are 17.30 ℃ and-3.70 ℃,respectively.For bridge thermal design,there are two vertical temperature difference models between top plate and bottom plate,and six horizontal temperature difference models in top plate.
文摘Since the early 1990, significant progress in database technology has provided new platform for emerging new dimensions of data engineering. New models were introduced to utilize the data sets stored in the new generations of databases. These models have a deep impact on evolving decision-support systems. But they suffer a variety of practical problems while accessing real-world data sources. Specifically a type of data storage model based on data distribution theory has been increasingly used in recent years by large-scale enterprises, while it is not compatible with existing decision-support models. This data storage model stores the data in different geographical sites where they are more regularly accessed. This leads to considerably less inter-site data transfer that can reduce data security issues in some circumstances and also significantly improve data manipulation transactions speed. The aim of this paper is to propose a new approach for supporting proactive decision-making that utilizes a workable data source management methodology. The new model can effectively organize and use complex data sources, even when they are distributed in different sites in a fragmented form. At the same time, the new model provides a very high level of intellectual management decision-support by intelligent use of the data collections through utilizing new smart methods in synthesizing useful knowledge. The results of an empirical study to evaluate the model are provided.
文摘Soil moisture characteristic curve （SMC） is a fundamental soil property and its direct measurement is tedious and time consuming. Therefore, various indirect methods have been developed to predict SMC from particle-size distribution （PSD）. However, the majority of these methods often yield intermittent SMC data because they involve estimating individual SMC points. The objectives of this study were 1） to develop a procedure to predict continuous SMC from a limited number of experimental PSD data points and 2） to evaluate model predictions through comparisons with measured values. In this study, an approach that allowed predicting SMC from the knowledge of PSD, parameterized by means of the closed-form van Genuchten model （VG）, was used. Through using Mohammadi and Vanclooster （MV） model, the parameters obtained from fitting of VG to PSD data were applied to predict SMC curves. Since the residual water content （Or） could not be obtained through fitting of VG-MV integrated model to PSD data, we also examined and compared four different methods estimating 0r. Results showed that the proposed equation （MV-VG integrated model） provided an excellent fit to all the PSD data and the model could adequately predict SMC as measured in forty-two soils sampled from different regions of Iran. For all soils, the method in which Or Was obtained through parameter optimization procedure provided the best overall predictions of SMC. The two methods estimating Or with Campbell and Shiozawa （CS） model resulted in less accuracy than the optimization procedure. Furthermore, the proposed model underestimated the moisture content in the dry range of SMC when the value of 0r was assumed to equal zero. 0r could be attributed to the incomplete desorption of water coated on soil particles and the accurate estimation of 0r was critical in prediction of SMC, especially for fine-textured soils at high suction heads. It could be concluded that the advantages of our approach were the continuity, robustness, and independency of model performance on soil type, allowing to improve predictions of SMC from PSD at the field and watershed scales.
基金supported by National Natural Science Foundation of China(Grant Nos.11271347 and 11171321)
文摘Modeling the mean and covariance simultaneously is a common strategy to efficiently estimate the mean parameters when applying generalized estimating equation techniques to longitudinal data. In this article, using generalized estimation equation techniques, we propose a new kind of regression models for parameterizing covariance structures. Using a novel Cholesky factor, the entries in this decomposition have moving average and log innovation interpretation and are modeled as the regression coefficients in both the mean and the linear functions of covariates. The resulting estimators for eovarianee are shown to be consistent and asymptotically normally distributed. Simulation studies and a real data analysis show that the proposed approach yields highly efficient estimators for the parameters in the mean, and provides parsimonious estimation for the covariance structure.
文摘Forests have long life cycles of up to several hundred years and longer.They also have very different growth rates at different stages of their life cycles.Therefore the carbon cycle in forest ecosystems has long time scales,making it necessary to consider forest age in estimating the spatiotemporal dynamics of carbon sinks in forests.The focus of this article is to review methods for combining recent remote sensing data with historical climate data for estimating the forest carbon source and sink distribution.Satellite remote sensing provides useful data for the land surface in recent decades. The information derived from remote sensing data can be used for short-term forest growth estimation and for mapping forest stand age for longterm simulations.For short-term forest growth estimation, remote sensing can provide forest structural parameters as inputs to process-based models,including big-leaf,two-leaf,and multi-layered models. These models use different strategies to upscale from leaf to canopy,and their reliability and suitability for remote sensing applications will be examined here.For long-term forest carbon cycle estimation, the spatial distribution of the forest growth rate（net primary productivity,NPP） modeled using remote sensing data in recent years is a critical input.This input can be combined with a forest age map to simulate the historical variation of NPP under the influence of climate and atmospheric changes. Another important component of the forest carbon cycle is heterotrophic respiration in the soil,which depends on the sizes of soil carbon pools as well as climate conditions.Methods for estimating the soil carbon spatial distribution and its separation into pools are described.The emphasis is placed on how to derive the soil carbon pools from NPP estimation in current years with consideration of forest carbon dynamics associated with stand age variation and climate and atmospheric changes.The role of disturbance in the forest carbon cycle and the effects of forest regrowth after disturbance are also considered in this review.An example of national forest carbon budget estimation in Canada is given at the end.It illustrates the importance of forest stand age structure in estimating the national forest carbon budgets and the effects of climate and atmospheric changes on the forest carbon cycle.
基金Supported by Council of Scientific and Industrial Research,New Delhi for This Work
文摘We study the centrality dependence of the mid-rapidity （｜y｜ 〈 0.5） yields and transverse momentum distributions of K＊ （892）° and φ（1020） resonances produced in Pb ＋ Pb collisions at SNN= 2.76 TeV. The mid- rapidity density （dN/dy） and the shape of the transverse momentum spectra are well reproduced by an earlier proposed Unified Statistical Thermal Freeze-out Model （USTFM）, which incorporates the effects of both longitudinal as well as transverse hydrodynamic flow. The freeze-out properties in terms of kinetic freeze-out temperature and transverse flow velocity parameter are extracted from the model fits to the transverse momentum data provided by the ALICE experiment at the LHC. The kinetic freeze-out temperature is found to increase with decreasing event centrality while the transverse flow velocity parameter shows a mild decrease on moving towards peripheral collisions. Moreover the centrality dependence of the mid-rapidity system size at freeze-out has also been studied in terms of transverse radius parameter.
文摘The Daya Bay Reactor Neutrino Experiment is to measure the smallest mixing angle θ13.The experiment contains three major experiment halls,Daya Bay near site,Linao near site and far site,and two major kinds of detectors,antineutrino detector which is to detect the antineutrinos by the inverse beta-decay reaction in Gd-LS,and muon detector which is to study and reject cosmogenic backgrounds.The goal of the detector control system(DCS)is to operate and detect the detectors and keep them running in safety.In consideration of the limited fund of this system and manpower of working on this system,the LabVIEW is chosen to develop the detector control system.The architecture of DCS adopts the distributed data management which is based on client-server model.The server part is to detect and operate parameters from hardware,save data to database and release data to clients,the client is to receive data from the server.The detector control system contains three parts:the hardware part,the local control system and the global control part.The local control system includes high voltage supply system,low voltage supply system,VME crate system,temperature and humidity system,gas pressure system,and so on.
文摘In this contribution, I identify possible biotic elements of reptiles of China using biotic element analysis. I test whether the vicariance model could significantly shape reptilian current distribution patterns. My results show that dispersal is prevailing for reptiles in China. There are four major biotic elements in reptilian distribution, which are East Xizang, Yunnan- Guizhou Plateau, Taiwan and Hainan, respectively. The test of distributional areas is significantly more clustered than expected by chance, while in another test that closely related species are homogeneously distributed across biotic elements cannot be rejected. Therefore I argued that vicariance might be one of the key processes in patterning reptilian distribution in China. In addition, I develop an improved biotic element analysis in biogeographic studies, by performing biotic element analysis in an iterative man- ner in order to diagnose more geographically restricted elements until no noise components found. The importance of antecedent selection of distributional data for the subsequent analysis is also discussed. Besides, my study indicates that biodiversity hotspots are not fully overlapped with areas of endemism for reptilians in East Asia
