The numerical simulation of the fluid flow and the flexible rod(s)interaction is more complicated and has lower efficiency due to the high computational cost.In this paper,a semi-resolved model coupling the computatio...The numerical simulation of the fluid flow and the flexible rod(s)interaction is more complicated and has lower efficiency due to the high computational cost.In this paper,a semi-resolved model coupling the computational fluid dynamics and the flexible rod dynamics is proposed using a two-way domain expansion method.The gov-erning equations of the flexible rod dynamics are discretized and solved by the finite element method,and the fluid flow is simulated by the finite volume method.The interaction between fluids and solid rods is modeled by introducing body force terms into the momentum equations.Referred to the traditional semi-resolved numerical model,an anisotropic Gaussian kernel function method is proposed to specify the interactive forces between flu-ids and solid bodies for non-circle rod cross-sections.A benchmark of the flow passing around a single flexible plate with a rectangular cross-section is used to validate the algorithm.Focused on the engineering applications,a test case of a finite patch of cylinders is implemented to validate the accuracy and efficiency of the coupled model.展开更多
In this paper, an Atmosphere-Vegetation Interaction Model （AVIM） is coupled to the Regional Integrated Environment Model System （RIEMS）, and a 10-year integration for China is performed using the RIEMS-AVIM. The a...In this paper, an Atmosphere-Vegetation Interaction Model （AVIM） is coupled to the Regional Integrated Environment Model System （RIEMS）, and a 10-year integration for China is performed using the RIEMS-AVIM. The analysis of the results of the 10-year integration shows that the characters of the spatial distributions of temperature and precipitation over China are well simulated. The patterns of simulated surface sensible and latent heat fluxes match well with the spatial climatological atlas： the values of winter surface sensible and latent heat fluxes are both lower than climatological values over the whole country. Summer surface sensible heat flux is higher than climatological values in western China and lower in eastern China, while summer surface latent heat flux is higher than climatological values in the eastern and lower in the western. Seasonal variations of simulated temperature and precipitation of RIMES-AVIM agree with those of the observed. Simulated temperature is lower than the observed in the Tibetan Plateau and Northwest China for the whole year, slightly lower in the remaining regions in winter, but consistent with the observed in summer. The simulated temperature of RIEMS-AVIM is higher in winter and lower in summer than that of RIEMS, which shows that the simulated temperature of RIEMS-AVIM is closer to the observed value. Simulated precipitation is excessive in the first half of the year, but consistent with the observed in the second half of the year. The simulated summer precipitation of RIEMS-AVIM has significant improvement compared to that of RIEMS, which is less and closer to the observed value. The interannual variations of temperature and precipitation are also fairly well simulated, with temperature simulation being superior to precipitation simulation. The interannual variation of simulated temperature is significantly correlated with the observed in Northeast China, the Transition Region, South China, and the Tibetan Plateau, but the correlation between precipitation simulation and observation is only significant in Northwest China.展开更多
The present paper describes a numerical two-way coupling model for shock-induced laminar boundary-layer flows of a dust-laden gas and studies the transverse migration of fine particles under the action of Saffman lift...The present paper describes a numerical two-way coupling model for shock-induced laminar boundary-layer flows of a dust-laden gas and studies the transverse migration of fine particles under the action of Saffman lift force. The governing equations are formulated in the dilute twophase continuum framework with consideration of the finiteness of the particle Reynolds and Knudsen numbers. The full Lagrangian method is explored for calculating the dispersedphase flow fields （including the number density of particles） in the regions of intersecting particle trajectories. The computation results show a significant reaction of the particles on the two-phase boundary-layer structure when the mass loading ratio of particles takes finite values.展开更多
In this paper,we consider the statistical inference problems for the fixed effect and variance component functions in the two-way classification random effects model with skewnormal errors.Firstly,the exact test stati...In this paper,we consider the statistical inference problems for the fixed effect and variance component functions in the two-way classification random effects model with skewnormal errors.Firstly,the exact test statistic for the fixed effect is constructed.Secondly,using the Bootstrap approach and generalized approach,the one-sided hypothesis testing and interval estimation problems for the single variance component,the sum and ratio of variance components are discussed respectively.Further,the Monte Carlo simulation results indicate that the exact test statistic performs well in the one-sided hypothesis testing problem for the fixed effect.And the Bootstrap approach is better than the generalized approach in the one-sided hypothesis testing problems for variance component functions in most cases.Finally,the above approaches are applied to the real data examples of the consumer price index and value-added index of three industries to verify their rationality and effectiveness.展开更多
Two-way feedback of human body was published in 1992. The sensation of two-way feedback of body is a special system of human reaction, which maintains and regulates symmetry and balance of human body. The human two-wa...Two-way feedback of human body was published in 1992. The sensation of two-way feedback of body is a special system of human reaction, which maintains and regulates symmetry and balance of human body. The human two-way feedback reacts to human health. For human overall health and delay decrepitude, it is necessary to pay attention to the stimulations (passive acceptance and initiative interventions) and relevant influences in human body and the stimulative effect. In this paper, the experimental research of stimulation and an example of two-way feedback in human body are given. And lay a foundation of prevention, medical treatment and hygiene of human overall health.展开更多
We present a three-level nested-grid ocean circulation modeling system for the Belize shelf of the western Caribbean Sea. The nested-grid system has three subcomponents： a coarse-resolution outer model of the western...We present a three-level nested-grid ocean circulation modeling system for the Belize shelf of the western Caribbean Sea. The nested-grid system has three subcomponents： a coarse-resolution outer model of the western Caribbean Sea; an intermediate-resolution middle model of the southern Mest〉American Barrier Reef System; and a fine-resolution inner model of the Belize shelf. The two-way nesting technique based on the semi-prognostic method is used to exchange information between the three subcomponents. We discuss two applications of the nested-grid system in this study. In the first application we simulate the seasonal mean circulation in the region, with the nested system forced by monthly mean surface fluxes and boundary forcing. The model results reproduce the general circulation features on the western Caribbean Sea and mest〉scale circulation features on the Belize shelf. In the second application, we simulate the storm-induced circulation during Hurricane Mitch in 1998, with the nested-grid system forced by the combination of monthly mean forcing and idealized wind stress associated with the storm. The model results demonstrate that the storm-induced currents transport a large amount of estuarine waters from coastal regions of Honduras and Guatemala to offshore reef atolls.展开更多
Objectives＂ To deepen our understanding of the status quo and to identify the hot topics and develop- mental trends of research on nursing models in countries other than China in the most recent decade. Methods： The...Objectives＂ To deepen our understanding of the status quo and to identify the hot topics and develop- mental trends of research on nursing models in countries other than China in the most recent decade. Methods： The study subjects were the publications retrieved from the PubMed database using the MeSH terms of ＂Models, Nursing＂. Bibliographic item co-occurrence mining system （BICOMS） software was used for conventional bibliometric analysis of publications during two time periods, 2005-2009 and 2010-2014. The number of published journal articles, journal distribution, authors of publications, country of origin of journals, and language of publications were analyzed to establish a high-frequency keyword profile and co-occurrence matrix. Graphical clustering toolkit （gCLUTO） software was applied for two-way clustering analysis and visualized analysis. Results： A total of 1472 journal articles with a key theme of nursing models were retrieved for final analysis, including 771 published during 2005-2009 and 701 during 2010-2014. The bibliometric analysis revealed that publications other than China concerning nursing models were mostly concentrated in the United States and the United Kingdom and that the number of relevant publications has been continuously decreasing. The two-way clustering analysis showed that there were mainly four types of research themes in the relevant publications in countries other than China during 2005-2009, i.e., nursing education and theoretical research, clinical nursing and psychological care, nursing administration, and models of nursing education, whereas there were five types during 2010-2014, i.e., nursing theories and clinical nursing practice, nursing administration models and assessments of nurses＇ knowledge and skills, community nursing administration models, nursing human resource management, and nursing education models and approaches. Conclusions： Research on nursing models in countries other than China is relatively mature and stable with a broader view, but it has shown a declining trend in recent years. It emphasizes both theory and practice, with research content tending to be structured into four modules, i.e., nursing education, administration, clinical practice, and theoretical research. Community nursing models may become a key research direction in the international research on nursing models in the future.展开更多
Precise and accurate rainfall simulation is essential for Tanzania, where complex topography and diverse climatic influences result in variable precipitation patterns. In this study, the 31st October 2023 to 02nd Nove...Precise and accurate rainfall simulation is essential for Tanzania, where complex topography and diverse climatic influences result in variable precipitation patterns. In this study, the 31st October 2023 to 02nd November 2023 daily observation rainfall was used to assess the performance of 5 land surface models (LSMs) and 7 microphysics schemes (MPs) using the Weather Research and Forecasting (WRF) model. The 35 different simulations were then evaluated using the observation data from the ground stations (OBS) and the gridded satellite (CHIRPS) dataset. It was found that the WSM6 scheme performed better than other MPs even though the performance of the LSMs was dependent on the observation data used. The CLM4 performed better than others when the simulations were compared with OBS whereas the 5 Layer Slab produced the lowest mean absolute error (MAE) and root mean square error (RMSE) values while the Noah-MP and RUC schemes produced the lowest average values of RMSE and MAE respectively when the CHIRPS dataset was used. The difference in performance of land surface models when compared to different sets of observation data was attributed to the fact that each observation dataset had a different number of points over the same area, influencing their performances. Furthermore, it was revealed that the CLM4-WSM6 combination performed better than others in the simulation of this event when it was compared against OBS while the 5 Layer Slab-WSM6 combination performed well when the CHIRPS dataset was used for comparison. This research highlights the critical role of the selection of land surface models and microphysics schemes in forecasting extreme rainfall events and underscores the importance of integrating different observational data for model validation. These findings contribute to improving predictive capabilities for extreme rainfall events in similar climatic regions.展开更多
[Objective] This study aimed to explore the impact of climate change on wheat cropping by using province-specific historical data during 1996-2007. [Method] We established a panel data econometric model with lagged wh...[Objective] This study aimed to explore the impact of climate change on wheat cropping by using province-specific historical data during 1996-2007. [Method] We established a panel data econometric model with lagged wheat cropping area and province-specific fixed-effects model to control the unobserved factors. [Result] The results showed that the temperature positively affects wheat cropping area, while precipitation does not have such impact. [Conclusion] The study provided empirical evidence for analysis of the determinants of wheat cropping area in China.展开更多
Erosion-corrosion of liquid-solid two-phase flow occurring in a pipe with sudden expansion in cross-section is numerically simulated in this paper. The global model for erosion-corrosion process includes three main co...Erosion-corrosion of liquid-solid two-phase flow occurring in a pipe with sudden expansion in cross-section is numerically simulated in this paper. The global model for erosion-corrosion process includes three main components: the liquid-solid two-phase flow model, erosion model and corrosion model. The Eulerian-Lagrangian approach is used to simulate liquid-solid two-phase flow, while the stochastic trajectory model was adopted to obtain properties of particle phase. Two-way coupling effect between the fluid and the particle phase is considered in the model. The accuracy of the models is tested by the data in the reference. The comparison shows that the model is basically correct and feasible.展开更多
While digital finance and renewable energy consumption(REC)are two timely issues,it remains unclear whether the former affects the latter,especially in developing economies.This paper examines the impact of digital fi...While digital finance and renewable energy consumption(REC)are two timely issues,it remains unclear whether the former affects the latter,especially in developing economies.This paper examines the impact of digital finance on China’s REC between 2011 and 2018 and explores the underlying mechanisms.Results show that digital finance,along with its coverage breadth and usage depth,significantly improved REC in China and that digital finance in the area of credit has had the most significant impact.Additionally,the results show that loan scale and income level are the main mediation variables,through which digital finance affects REC.The findings also suggest that economic growth and technological progress have increased REC in China,while carbon dioxide emissions have had no meaningful effect on this consumption.The results further indicate that policymakers must pay close attention to the role of digital finance when formulating policies on REC.To promote REC and environmental sustainability,developing economies like China should strengthen the breadth and depth of digital finance development,focus on the influence channels of digital finance,and promote economic growth and technological progress.展开更多
Based on the systematic analysis of the operation process at two-way marshaling station, the operation ways of through car flows, sorting car flows and loading car flows are comprehensively studied. An optimal model o...Based on the systematic analysis of the operation process at two-way marshaling station, the operation ways of through car flows, sorting car flows and loading car flows are comprehensively studied. An optimal model of system operation division of labor based on resource constraint is constructed. The model is solved by using genetic algorithm, and the improving strategy for solving the model is proposed. The application example indicates that the model and algorithm can effectively solve the problem of operation division of labor at two-way marshaling station.展开更多
In this paper,using the Bootstrap approach and generalized approach,the authors consider the one-sided hypothesis testing problems for variance component functions in the two-way random effects model.Firstly,the test ...In this paper,using the Bootstrap approach and generalized approach,the authors consider the one-sided hypothesis testing problems for variance component functions in the two-way random effects model.Firstly,the test statistics and confidence intervals for the sum of variance components are constructed.Next,the one-sided hypothesis testing problems for the ratio of variance components are also discussed.The Monte Carlo simulation results indicate that the Bootstrap approach is better than the generalized approach in most cases.Finally,the above approaches are applied to the real data examples of mice blood p H and molded plastic part’s dimensions.展开更多
Timberland investment opportunities in Colombia are expected to increase as a result of the peace agreement recently signed between the Colombian government and the Revolutionary Armed Forces of Colombia. This new soc...Timberland investment opportunities in Colombia are expected to increase as a result of the peace agreement recently signed between the Colombian government and the Revolutionary Armed Forces of Colombia. This new socio-political environment may facilitate the expansion of commercial forest plantations on a wider range of site conditions that are currently considered in existing biometric tools. Data from 1119 temporary plots of unthinned, unmanaged, and genetically unimproved Pinus patula plantations in the Antioquia region were combined with a large set of biophysical attributes to identify spatial variation in yield. A wide array of biophysical covariates was explored to characterize the most favorable environmental conditions for the species, and to identify potential explanatory variables to be included in forest yield models. The mathematical form of the model is the von Bertalanffy-Chapman-Richards type, with parameters: asymptote, intrinsic growth rate and allometric constant. The parameters were expressed as linear functions of soil pH, terrain slope, the mean annual temperature to mean annual precipitation ratio, and stand density. The statistical contribution of selected covariates was evaluated using the likelihood ratio test. The model was validated using an independent set of 133 observations. The spatial representation of the model depicts the timber production potential and allows for the identification of the most suitable geographical areas to establish Pinus patula plantations in Antioquia, Colombia. The estimated yield model provides a reliable baseline for timber production, and insight into timberland investments in Colombia.展开更多
A computational fluid dynamics model is used for the simulation of laminar flow ofwater-Al2O3 nanofluid in a confined slot impinging jet. The （steady-state and two-dimensional） Eulerian-Lagrangian model is used cons...A computational fluid dynamics model is used for the simulation of laminar flow ofwater-Al2O3 nanofluid in a confined slot impinging jet. The （steady-state and two-dimensional） Eulerian-Lagrangian model is used considering fluid-particle and particle-wall interactions （i.e., two-way coupling）. A collocated grid and the SIMPLE algorithm are used for the coupling of pressure and velocity fields. The deposition model is used to investigate the effect of particle deposition on the impingement surface. Results indicate that the particle trajectory becomes stable farther from the jet with a rising Reynolds number and jet- impingement surface distance ratio. The heat transfer coefficient of the mixture model is higher than that of the Eulerian-Lagrangican model.展开更多
The Severn Estuary has one of the largest tidal ranges in the world and has long been the subject of consideration for tidal energy generation.Whilst plans to build a tidal barrage across the estuary have existed in v...The Severn Estuary has one of the largest tidal ranges in the world and has long been the subject of consideration for tidal energy generation.Whilst plans to build a tidal barrage across the estuary have existed in various forms since the 1920s,the 1989Severn Tidal Power Group(STPG)proposal is commonly referred to as the original Severn Barrage.The UK government abandoned this ebb generation scheme as a public investment project in 2010.However,plans to build a two-way generation scheme were more recently put forward by a private consortium,namely Hafren Power.To assess the impact that a barrage would have on the hydro-environment in the estuary a number of numerical modelling studies have previously been conducted for the STPG scheme.As this design has now been superseded by the Hafren Power proposal,new studies have been conducted to investigate the impact of a two-way scheme.In this study the hydro-environmental impacts of both ebb-only and two-way schemes were assessed using physical and numerical modelling techniques.Scale model barrages were constructed and testing was carried out using a physical model of the Severn Estuary,located in the hydraulics laboratory at Cardiff University.A depth integrated numerical model,namely DIVAST,was applied to the physical model geometry and modifications were made to simulate the effects of the barrage structures.The numerical model predictions showed good agreement with the corresponding laboratory data.The results were consistent with conclusions from previous studies,relating to the ebb-only scheme.These included an increase in the minimum water levels upstream of the barrage,a reduction in the mean water levels downstream of the barrage and a general reduction in tidal velocities.For a two-way scheme changes in the tidal elevations and velocities depended on the exact operating conditions of the barrage.It was found that with no starting head the tidal regime was similar to the natural state,with little change in the elevations and a slight reduction in the mean velocities.As a starting head was introduced there was still little change in elevations downstream of the barrage,however,there was an increase in the minimum water levels upstream of the barrage,and a further reduction in the mean velocities.展开更多
Staining algorithms based on two-way wave equation migration methods have been applied to improve the signal-to-noise ratio(SNR)of poorly illuminated structures such as those in subsalt zones.In regular staining algor...Staining algorithms based on two-way wave equation migration methods have been applied to improve the signal-to-noise ratio(SNR)of poorly illuminated structures such as those in subsalt zones.In regular staining algorithms,when a source wavefield reaches the stained area that is associated with the target structures,a new wavefield called stained wavefield is excited,and this stained wavefield forward extrapolates synchronously with the real source wavefield.The forward-extrapolated stained and real source wavefields are cross-correlated with the backward-extrapolated receiver wavefield,and we obtain the stained and the real reverse time migration(RTM)images.The staining algorithms for RTM can suppress the noise of non-target regions and obtain high SNR images of the target structures.Whereas RTM methods are limited by the low computational efficiency and SNR,by contrast,one-way wave equation migration(OWEM)methods have the advantages of high efficiency and no interference from multiples.Thus,we developed a new staining method based on the generalised screen propagator(GSP)as a case of OWEM methods for subsalt imaging.Furthermore,a new stained wavefield called stained receiver wavefield is proposed here,forming two new staining strategies for seismic imaging,in which forward-propagated source and backward-propagated receiver wavefields can be conveniently selected to be stained at the stained area.Numerical experiments demonstrated that this staining GSP method is more effective in improving the SNR of subsalt structures compared to conventional GSP migration and RTM methods;moreover,these new staining strategies as applied to the OWEM methods can greatly improve the SNR of weakly illuminated structures in subsalt zones,in comparison with regular staining algorithms for one-way methods.展开更多
China has launched six Priority Forestry Programs (PFPs) since 1998, i.e. the Natural Forest Protection Program, the Cropland Conversion to Forest and Grassland Program, Sandification Control Program for the Vicinity ...China has launched six Priority Forestry Programs (PFPs) since 1998, i.e. the Natural Forest Protection Program, the Cropland Conversion to Forest and Grassland Program, Sandification Control Program for the Vicinity of Beijing & Tianjin , Wildlife Conservation and Nature Reserve Development Program, Forest Industrial Base Development Program and Shelterbelt Development Programs for regions such as Three North and the Yangtze River Catchments. The Government of China has made different policies for these PFPs, such as subsidies, low-interest loans and revenue offsets. Using a fixed-effect model and panel data from 2 353 households in 9 counties of Sichuan, Hebei, Shaanxi, and Jiangxi provinces, this paper studies effects of PFPs on farmers’ incomes. The empirical results indicate that the effects of PFPs on farmers’ incomes are mixed. Overall, the impact of Conversion of Cropland to Forestland and Grassland Program is significantly positive, whereas that of the Natural Forest Protection Program and the Sandification Control Program around Beijing & Tianjin is negative. To a lesser extent, the Shelterbelt Development Programs have a positive impact. In the meantime, different effects of PFPs on farmers’ incomes are also mixed for different provinces and different households are also mixed.展开更多
The process to achieve time synchronization and ranging for a network of mobile nodes is raising a concern among researchers, and hence a variety of joint time synchronization and ranging algorithms have been proposed...The process to achieve time synchronization and ranging for a network of mobile nodes is raising a concern among researchers, and hence a variety of joint time synchronization and ranging algorithms have been proposed in recent years. However, few of them handle the case of all-node motion under unknown positions and velocities. This study addresses the problem of determining ranging and time synchronization for a group of nodes moving within a local area. First, we examined several models of clock discrepancy and synchronous two-way ranging. Based upon these models, we present a solution for time synchronization with known positions and velocities. Next, we propose a functional model that jointly estimates the clock skew, clock offset, and time of flight in the absence of a priori knowledge for a pair of mobile nodes. Then, we extend this model to a network-wide time synchronization scheme by way of a global least square estimator. We also discuss the advantages and disadvantages of our model compared to the existing algorithms, and we provide some applicable scenarios as well. Finally, we show that the simulation results verify the validity of our analysis.展开更多
基金supported by Shanghai 2021“Science and Technology Innovation Action Plan”:Social Development Science and Technology Research Project(Grant No.21DZ1202703).
文摘The numerical simulation of the fluid flow and the flexible rod(s)interaction is more complicated and has lower efficiency due to the high computational cost.In this paper,a semi-resolved model coupling the computational fluid dynamics and the flexible rod dynamics is proposed using a two-way domain expansion method.The gov-erning equations of the flexible rod dynamics are discretized and solved by the finite element method,and the fluid flow is simulated by the finite volume method.The interaction between fluids and solid rods is modeled by introducing body force terms into the momentum equations.Referred to the traditional semi-resolved numerical model,an anisotropic Gaussian kernel function method is proposed to specify the interactive forces between flu-ids and solid bodies for non-circle rod cross-sections.A benchmark of the flow passing around a single flexible plate with a rectangular cross-section is used to validate the algorithm.Focused on the engineering applications,a test case of a finite patch of cylinders is implemented to validate the accuracy and efficiency of the coupled model.
基金the National Basic Research Program of China from the Ministry of Science and Technology of China (Grant No. 2006CB400500 and 2007CB411505)the National Natural Science Foundation of China (Grant No. 40705031)
文摘In this paper, an Atmosphere-Vegetation Interaction Model （AVIM） is coupled to the Regional Integrated Environment Model System （RIEMS）, and a 10-year integration for China is performed using the RIEMS-AVIM. The analysis of the results of the 10-year integration shows that the characters of the spatial distributions of temperature and precipitation over China are well simulated. The patterns of simulated surface sensible and latent heat fluxes match well with the spatial climatological atlas： the values of winter surface sensible and latent heat fluxes are both lower than climatological values over the whole country. Summer surface sensible heat flux is higher than climatological values in western China and lower in eastern China, while summer surface latent heat flux is higher than climatological values in the eastern and lower in the western. Seasonal variations of simulated temperature and precipitation of RIMES-AVIM agree with those of the observed. Simulated temperature is lower than the observed in the Tibetan Plateau and Northwest China for the whole year, slightly lower in the remaining regions in winter, but consistent with the observed in summer. The simulated temperature of RIEMS-AVIM is higher in winter and lower in summer than that of RIEMS, which shows that the simulated temperature of RIEMS-AVIM is closer to the observed value. Simulated precipitation is excessive in the first half of the year, but consistent with the observed in the second half of the year. The simulated summer precipitation of RIEMS-AVIM has significant improvement compared to that of RIEMS, which is less and closer to the observed value. The interannual variations of temperature and precipitation are also fairly well simulated, with temperature simulation being superior to precipitation simulation. The interannual variation of simulated temperature is significantly correlated with the observed in Northeast China, the Transition Region, South China, and the Tibetan Plateau, but the correlation between precipitation simulation and observation is only significant in Northwest China.
基金The project supported by the National Natural Science Foundation of China(90205024)Russian Foundation for Basic Research(RFBR and(RFBR-NSFC-39004)
文摘The present paper describes a numerical two-way coupling model for shock-induced laminar boundary-layer flows of a dust-laden gas and studies the transverse migration of fine particles under the action of Saffman lift force. The governing equations are formulated in the dilute twophase continuum framework with consideration of the finiteness of the particle Reynolds and Knudsen numbers. The full Lagrangian method is explored for calculating the dispersedphase flow fields （including the number density of particles） in the regions of intersecting particle trajectories. The computation results show a significant reaction of the particles on the two-phase boundary-layer structure when the mass loading ratio of particles takes finite values.
基金supported by National Social Science Foundation of China(21BTJ068)。
文摘In this paper,we consider the statistical inference problems for the fixed effect and variance component functions in the two-way classification random effects model with skewnormal errors.Firstly,the exact test statistic for the fixed effect is constructed.Secondly,using the Bootstrap approach and generalized approach,the one-sided hypothesis testing and interval estimation problems for the single variance component,the sum and ratio of variance components are discussed respectively.Further,the Monte Carlo simulation results indicate that the exact test statistic performs well in the one-sided hypothesis testing problem for the fixed effect.And the Bootstrap approach is better than the generalized approach in the one-sided hypothesis testing problems for variance component functions in most cases.Finally,the above approaches are applied to the real data examples of the consumer price index and value-added index of three industries to verify their rationality and effectiveness.
文摘Two-way feedback of human body was published in 1992. The sensation of two-way feedback of body is a special system of human reaction, which maintains and regulates symmetry and balance of human body. The human two-way feedback reacts to human health. For human overall health and delay decrepitude, it is necessary to pay attention to the stimulations (passive acceptance and initiative interventions) and relevant influences in human body and the stimulative effect. In this paper, the experimental research of stimulation and an example of two-way feedback in human body are given. And lay a foundation of prevention, medical treatment and hygiene of human overall health.
文摘We present a three-level nested-grid ocean circulation modeling system for the Belize shelf of the western Caribbean Sea. The nested-grid system has three subcomponents： a coarse-resolution outer model of the western Caribbean Sea; an intermediate-resolution middle model of the southern Mest〉American Barrier Reef System; and a fine-resolution inner model of the Belize shelf. The two-way nesting technique based on the semi-prognostic method is used to exchange information between the three subcomponents. We discuss two applications of the nested-grid system in this study. In the first application we simulate the seasonal mean circulation in the region, with the nested system forced by monthly mean surface fluxes and boundary forcing. The model results reproduce the general circulation features on the western Caribbean Sea and mest〉scale circulation features on the Belize shelf. In the second application, we simulate the storm-induced circulation during Hurricane Mitch in 1998, with the nested-grid system forced by the combination of monthly mean forcing and idealized wind stress associated with the storm. The model results demonstrate that the storm-induced currents transport a large amount of estuarine waters from coastal regions of Honduras and Guatemala to offshore reef atolls.
基金supported by Shanxi Provincial Health Department(No.201201031)
文摘Objectives＂ To deepen our understanding of the status quo and to identify the hot topics and develop- mental trends of research on nursing models in countries other than China in the most recent decade. Methods： The study subjects were the publications retrieved from the PubMed database using the MeSH terms of ＂Models, Nursing＂. Bibliographic item co-occurrence mining system （BICOMS） software was used for conventional bibliometric analysis of publications during two time periods, 2005-2009 and 2010-2014. The number of published journal articles, journal distribution, authors of publications, country of origin of journals, and language of publications were analyzed to establish a high-frequency keyword profile and co-occurrence matrix. Graphical clustering toolkit （gCLUTO） software was applied for two-way clustering analysis and visualized analysis. Results： A total of 1472 journal articles with a key theme of nursing models were retrieved for final analysis, including 771 published during 2005-2009 and 701 during 2010-2014. The bibliometric analysis revealed that publications other than China concerning nursing models were mostly concentrated in the United States and the United Kingdom and that the number of relevant publications has been continuously decreasing. The two-way clustering analysis showed that there were mainly four types of research themes in the relevant publications in countries other than China during 2005-2009, i.e., nursing education and theoretical research, clinical nursing and psychological care, nursing administration, and models of nursing education, whereas there were five types during 2010-2014, i.e., nursing theories and clinical nursing practice, nursing administration models and assessments of nurses＇ knowledge and skills, community nursing administration models, nursing human resource management, and nursing education models and approaches. Conclusions： Research on nursing models in countries other than China is relatively mature and stable with a broader view, but it has shown a declining trend in recent years. It emphasizes both theory and practice, with research content tending to be structured into four modules, i.e., nursing education, administration, clinical practice, and theoretical research. Community nursing models may become a key research direction in the international research on nursing models in the future.
文摘Precise and accurate rainfall simulation is essential for Tanzania, where complex topography and diverse climatic influences result in variable precipitation patterns. In this study, the 31st October 2023 to 02nd November 2023 daily observation rainfall was used to assess the performance of 5 land surface models (LSMs) and 7 microphysics schemes (MPs) using the Weather Research and Forecasting (WRF) model. The 35 different simulations were then evaluated using the observation data from the ground stations (OBS) and the gridded satellite (CHIRPS) dataset. It was found that the WSM6 scheme performed better than other MPs even though the performance of the LSMs was dependent on the observation data used. The CLM4 performed better than others when the simulations were compared with OBS whereas the 5 Layer Slab produced the lowest mean absolute error (MAE) and root mean square error (RMSE) values while the Noah-MP and RUC schemes produced the lowest average values of RMSE and MAE respectively when the CHIRPS dataset was used. The difference in performance of land surface models when compared to different sets of observation data was attributed to the fact that each observation dataset had a different number of points over the same area, influencing their performances. Furthermore, it was revealed that the CLM4-WSM6 combination performed better than others in the simulation of this event when it was compared against OBS while the 5 Layer Slab-WSM6 combination performed well when the CHIRPS dataset was used for comparison. This research highlights the critical role of the selection of land surface models and microphysics schemes in forecasting extreme rainfall events and underscores the importance of integrating different observational data for model validation. These findings contribute to improving predictive capabilities for extreme rainfall events in similar climatic regions.
基金Supported by the National Natural Science Foundation of China (41101165)~~
文摘[Objective] This study aimed to explore the impact of climate change on wheat cropping by using province-specific historical data during 1996-2007. [Method] We established a panel data econometric model with lagged wheat cropping area and province-specific fixed-effects model to control the unobserved factors. [Result] The results showed that the temperature positively affects wheat cropping area, while precipitation does not have such impact. [Conclusion] The study provided empirical evidence for analysis of the determinants of wheat cropping area in China.
基金Supported by the National Natural Science Foundation of China(N.59831030).
文摘Erosion-corrosion of liquid-solid two-phase flow occurring in a pipe with sudden expansion in cross-section is numerically simulated in this paper. The global model for erosion-corrosion process includes three main components: the liquid-solid two-phase flow model, erosion model and corrosion model. The Eulerian-Lagrangian approach is used to simulate liquid-solid two-phase flow, while the stochastic trajectory model was adopted to obtain properties of particle phase. Two-way coupling effect between the fluid and the particle phase is considered in the model. The accuracy of the models is tested by the data in the reference. The comparison shows that the model is basically correct and feasible.
基金Research of Universities in Jiangsu Province(2021SJA1269)the Major Program Project of the National Social Science Fund of China(No:19ZDA055)+2 种基金Zhejiang Provincial Natural Science Foundation of China(Q22G037055)Major projects of Humanities and Social Sciences in Zhejiang Province(21096054-F)Zhejiang Sci-Tech University Scientific Research Fund(No:21092117-Y).
文摘While digital finance and renewable energy consumption(REC)are two timely issues,it remains unclear whether the former affects the latter,especially in developing economies.This paper examines the impact of digital finance on China’s REC between 2011 and 2018 and explores the underlying mechanisms.Results show that digital finance,along with its coverage breadth and usage depth,significantly improved REC in China and that digital finance in the area of credit has had the most significant impact.Additionally,the results show that loan scale and income level are the main mediation variables,through which digital finance affects REC.The findings also suggest that economic growth and technological progress have increased REC in China,while carbon dioxide emissions have had no meaningful effect on this consumption.The results further indicate that policymakers must pay close attention to the role of digital finance when formulating policies on REC.To promote REC and environmental sustainability,developing economies like China should strengthen the breadth and depth of digital finance development,focus on the influence channels of digital finance,and promote economic growth and technological progress.
文摘Based on the systematic analysis of the operation process at two-way marshaling station, the operation ways of through car flows, sorting car flows and loading car flows are comprehensively studied. An optimal model of system operation division of labor based on resource constraint is constructed. The model is solved by using genetic algorithm, and the improving strategy for solving the model is proposed. The application example indicates that the model and algorithm can effectively solve the problem of operation division of labor at two-way marshaling station.
基金Zhejiang Provincial Natural Science Foundation of China under Grant No.LY20A010019Ministry of Education of China+4 种基金Humanities and Social Science Projects under Grant No.19YJA910006Fundamental Research Funds for the Provincial Universities of Zhejiang under Grant No.GK199900299012-204Zhejiang Provincial Philosophy and Social Science Planning Zhijiang Youth Project of China under Grant No.16ZJQN017YBZhejiang Provincial Statistical Science Research Base Project of China under Grant No.19TJJD08Scientific Research and Innovation Foundation of Hangzhou Dianzi University under Grant No.CXJJ2019008。
文摘In this paper,using the Bootstrap approach and generalized approach,the authors consider the one-sided hypothesis testing problems for variance component functions in the two-way random effects model.Firstly,the test statistics and confidence intervals for the sum of variance components are constructed.Next,the one-sided hypothesis testing problems for the ratio of variance components are also discussed.The Monte Carlo simulation results indicate that the Bootstrap approach is better than the generalized approach in most cases.Finally,the above approaches are applied to the real data examples of mice blood p H and molded plastic part’s dimensions.
文摘Timberland investment opportunities in Colombia are expected to increase as a result of the peace agreement recently signed between the Colombian government and the Revolutionary Armed Forces of Colombia. This new socio-political environment may facilitate the expansion of commercial forest plantations on a wider range of site conditions that are currently considered in existing biometric tools. Data from 1119 temporary plots of unthinned, unmanaged, and genetically unimproved Pinus patula plantations in the Antioquia region were combined with a large set of biophysical attributes to identify spatial variation in yield. A wide array of biophysical covariates was explored to characterize the most favorable environmental conditions for the species, and to identify potential explanatory variables to be included in forest yield models. The mathematical form of the model is the von Bertalanffy-Chapman-Richards type, with parameters: asymptote, intrinsic growth rate and allometric constant. The parameters were expressed as linear functions of soil pH, terrain slope, the mean annual temperature to mean annual precipitation ratio, and stand density. The statistical contribution of selected covariates was evaluated using the likelihood ratio test. The model was validated using an independent set of 133 observations. The spatial representation of the model depicts the timber production potential and allows for the identification of the most suitable geographical areas to establish Pinus patula plantations in Antioquia, Colombia. The estimated yield model provides a reliable baseline for timber production, and insight into timberland investments in Colombia.
文摘A computational fluid dynamics model is used for the simulation of laminar flow ofwater-Al2O3 nanofluid in a confined slot impinging jet. The （steady-state and two-dimensional） Eulerian-Lagrangian model is used considering fluid-particle and particle-wall interactions （i.e., two-way coupling）. A collocated grid and the SIMPLE algorithm are used for the coupling of pressure and velocity fields. The deposition model is used to investigate the effect of particle deposition on the impingement surface. Results indicate that the particle trajectory becomes stable farther from the jet with a rising Reynolds number and jet- impingement surface distance ratio. The heat transfer coefficient of the mixture model is higher than that of the Eulerian-Lagrangican model.
基金supported by the LCRI projectpart funded by the Welsh Government+2 种基金the Higher Education Funding Council for Walesthe Welsh European Funding Officethe European Regional Development Fund (ERDF) Convergence Programme
文摘The Severn Estuary has one of the largest tidal ranges in the world and has long been the subject of consideration for tidal energy generation.Whilst plans to build a tidal barrage across the estuary have existed in various forms since the 1920s,the 1989Severn Tidal Power Group(STPG)proposal is commonly referred to as the original Severn Barrage.The UK government abandoned this ebb generation scheme as a public investment project in 2010.However,plans to build a two-way generation scheme were more recently put forward by a private consortium,namely Hafren Power.To assess the impact that a barrage would have on the hydro-environment in the estuary a number of numerical modelling studies have previously been conducted for the STPG scheme.As this design has now been superseded by the Hafren Power proposal,new studies have been conducted to investigate the impact of a two-way scheme.In this study the hydro-environmental impacts of both ebb-only and two-way schemes were assessed using physical and numerical modelling techniques.Scale model barrages were constructed and testing was carried out using a physical model of the Severn Estuary,located in the hydraulics laboratory at Cardiff University.A depth integrated numerical model,namely DIVAST,was applied to the physical model geometry and modifications were made to simulate the effects of the barrage structures.The numerical model predictions showed good agreement with the corresponding laboratory data.The results were consistent with conclusions from previous studies,relating to the ebb-only scheme.These included an increase in the minimum water levels upstream of the barrage,a reduction in the mean water levels downstream of the barrage and a general reduction in tidal velocities.For a two-way scheme changes in the tidal elevations and velocities depended on the exact operating conditions of the barrage.It was found that with no starting head the tidal regime was similar to the natural state,with little change in the elevations and a slight reduction in the mean velocities.As a starting head was introduced there was still little change in elevations downstream of the barrage,however,there was an increase in the minimum water levels upstream of the barrage,and a further reduction in the mean velocities.
基金support from the National Key Research and Development Program of China(No.2017YFB0202903)the National Natural Science Foundation of China(41774121).
文摘Staining algorithms based on two-way wave equation migration methods have been applied to improve the signal-to-noise ratio(SNR)of poorly illuminated structures such as those in subsalt zones.In regular staining algorithms,when a source wavefield reaches the stained area that is associated with the target structures,a new wavefield called stained wavefield is excited,and this stained wavefield forward extrapolates synchronously with the real source wavefield.The forward-extrapolated stained and real source wavefields are cross-correlated with the backward-extrapolated receiver wavefield,and we obtain the stained and the real reverse time migration(RTM)images.The staining algorithms for RTM can suppress the noise of non-target regions and obtain high SNR images of the target structures.Whereas RTM methods are limited by the low computational efficiency and SNR,by contrast,one-way wave equation migration(OWEM)methods have the advantages of high efficiency and no interference from multiples.Thus,we developed a new staining method based on the generalised screen propagator(GSP)as a case of OWEM methods for subsalt imaging.Furthermore,a new stained wavefield called stained receiver wavefield is proposed here,forming two new staining strategies for seismic imaging,in which forward-propagated source and backward-propagated receiver wavefields can be conveniently selected to be stained at the stained area.Numerical experiments demonstrated that this staining GSP method is more effective in improving the SNR of subsalt structures compared to conventional GSP migration and RTM methods;moreover,these new staining strategies as applied to the OWEM methods can greatly improve the SNR of weakly illuminated structures in subsalt zones,in comparison with regular staining algorithms for one-way methods.
文摘China has launched six Priority Forestry Programs (PFPs) since 1998, i.e. the Natural Forest Protection Program, the Cropland Conversion to Forest and Grassland Program, Sandification Control Program for the Vicinity of Beijing & Tianjin , Wildlife Conservation and Nature Reserve Development Program, Forest Industrial Base Development Program and Shelterbelt Development Programs for regions such as Three North and the Yangtze River Catchments. The Government of China has made different policies for these PFPs, such as subsidies, low-interest loans and revenue offsets. Using a fixed-effect model and panel data from 2 353 households in 9 counties of Sichuan, Hebei, Shaanxi, and Jiangxi provinces, this paper studies effects of PFPs on farmers’ incomes. The empirical results indicate that the effects of PFPs on farmers’ incomes are mixed. Overall, the impact of Conversion of Cropland to Forestland and Grassland Program is significantly positive, whereas that of the Natural Forest Protection Program and the Sandification Control Program around Beijing & Tianjin is negative. To a lesser extent, the Shelterbelt Development Programs have a positive impact. In the meantime, different effects of PFPs on farmers’ incomes are also mixed for different provinces and different households are also mixed.
基金supported by the National Natural Science Foundation of China(Grant No.61471021)
文摘The process to achieve time synchronization and ranging for a network of mobile nodes is raising a concern among researchers, and hence a variety of joint time synchronization and ranging algorithms have been proposed in recent years. However, few of them handle the case of all-node motion under unknown positions and velocities. This study addresses the problem of determining ranging and time synchronization for a group of nodes moving within a local area. First, we examined several models of clock discrepancy and synchronous two-way ranging. Based upon these models, we present a solution for time synchronization with known positions and velocities. Next, we propose a functional model that jointly estimates the clock skew, clock offset, and time of flight in the absence of a priori knowledge for a pair of mobile nodes. Then, we extend this model to a network-wide time synchronization scheme by way of a global least square estimator. We also discuss the advantages and disadvantages of our model compared to the existing algorithms, and we provide some applicable scenarios as well. Finally, we show that the simulation results verify the validity of our analysis.
