A numerical model for cloud cavitation based on bubble cluster

The cavitation cloud of different internal structures results in different collapse pressures owing to the interaction among bubbles. The internal structure of cloud cavitation is required to accurately predict collapse pressure. A cavitation model was developed through dimensional analysis and direct numerical simulation of collapse of bubble cluster. Bubble number density was included in proposed model to characterize the internal structure of bubble cloud. Implemented on flows over a projectile, the proposed model predicts a higher collapse pressure compared with Singhal model. Results indicate that the collapse pressure of detached cavitation cloud is affected by bubble number density.

Cold-modeling study of a circulating fluidized bed reactor for flue gas desulfurization (FGD)

Short residence time of the sorbent in the gas stream and formation of a dense layer of reaction product surrounding its surface influence the sulfur removal efficiency. A practical means of improving the process performance is to employ fluidized bed reaction in replacement of entrained bed reaction on normally used in cool side desulfurizaiton. This paper describes cold modeling study of a circulating fluidized bed reactor. Several aspects of the problem are discussed: fluidization behavior of CaO, attrition of the sorbent and solids entrainment from the fluidized bed. Mechanisms and key controlling parameters are identified, and an integral model based on rate of attrition and mass balance is developed for predicting steady state mass flows and particle size distributions of the system. A process flow scheme is finally presented for conducting desulfurization tests in the second stage of the study.

Traditional Chinese medicine Qi model

This paper expounds the effect of"Qi"on human body by constructing the model of Qi,classifies the parts according to the category of Yin and Yang on the coordinate frame of 5 models of Yin and Yang,and compares each kind of parts according to the normal image state of human body.with the running direction of integer instead of Qi,the number of Qi in each part is calculated by the method of modern number theory,and the development and changes of human physiology and diseases are explained by"Qi".To explore the Trasitional Chinese Medicine treatment method of"the morbid Qi state of the human body adjusts the qi mode,the direction of qi operation and the intensity of Qi by means of medicinal taste and acupuncture,and returns to the normal state of qi balance mode in the direction of operation".

Effects of thermophoresis particle deposition and of the thermal conductivity in a porous plate with dissipative heat and mass transfer

Network simulation method（NSM） is used to solve the laminar heat and mass transfer of an electricallyconducting,heat generating/absorbing fluid past a perforated horizontal surface in the presence of viscous and Joule heating problem. The governing partial differential equations are non-dimensionalized and transformed into a system of nonlinear ordinary differential similarity equations,in a single independent variable,畏. The resulting coupled,nonlinear equations are solved under appropriate transformed boundary conditions. Computations are performed for a wide range of the governing flow parameters,viz Prandtl number,thermophoretic coeffcient（a function of Knudsen number）,thermal conductivity parameter,wall transpiration parameter and Schmidt number. The numerical details are discussed with relevant applications. The present problem finds applications in optical fiber fabrication,aerosol filter precipitators,particle deposition on hydronautical blades,semiconductor wafer design,thermo-electronics and problems including nuclear reactor safety.

Identification of potential soil water retention using hydric numerical model at arid regions by land-use changes

Assessment of soil water retention in arid region is an input required parameter in precision water management at large scale.Investigations were carried out in Tanta catchment in the middle Nile Delta,Egypt(30145 N,30155 E),where collecting soil samples covered different hydrological soil groups and land-uses.Based on the natural resource conservation service curve number model(NRCS-CN),CN approach was used to investigate the effect of spatio-temporal variations of different land-uses on soil water retention.Potential soil water retention from 1990 to 2015 was reduced by 118.1 m^(3) per hectare with decreasing cropland area.Urbanization encroachment from 1990 to 2015 was increased by 2.13%by decreasing cropland with 15.3%(5300 ha in 2015).This resulted in losing the potential soil water retention by 625,968.42 m^(3) water for the whole catchment area.Impact of land degradation was pronounced,where 2.65%,29.35%,and 1.11%of the initial crop land-use in 1990 were converted to bare soil,fallow,and urban area,respectively in 2015.Implementation of(S)value of the NRCS-CN model with GIS technique provides useful measure to identify land-use changes of potential water storage capacity at catchment scale.

Evaluation of alternative surface runoff accounting procedures using SWAT model

For surface runoff estimation in the Soil and Water Assessment Tool(SWAT)model,the curve number(CN)procedure is commonly adopted to calculate surface runoff by dynamically updating CN values based on antecedent soil moisture condition(SCSI)in field.From SWAT2005 and onward,an alternative approach has become available to apply the CN method by relating the runoff potential to daily evapotranspiration(SCSII).While improved runoff prediction with SCSII has been reported in several case studies,few investigations have been made on its influence to water quality output or on the model uncertainty associated with the SCSII method.The objectives of the research were:(1)to quantify the improvements in hydrologic and water quality predictions obtained through different surface runoff estimation techniques;and(2)to examine how model uncertainty is affected by combining different surface runoff estimation techniques within SWAT using Bayesian model averaging(BMA).Applications of BMA provide an alternative approach to investigate the nature of structural uncertainty associated with both CN methods.Results showed that SCSII and BMA associated approaches exhibit improved performance in both discharge and total NO3 predictions compared to SCSI.In addition,the application of BMA has a positive effect on finding well performed solutions in the multi-dimensional parameter space,but the predictive uncertainty is not evidently reduced or enhanced.Therefore,we recommend additional future SWAT calibration/validation research with an emphasis on the impact of SCSII on the prediction of other pollutants.

Dynamics of freezing/thawing indices and frozen ground from 1900 to 2017 in the upper Brahmaputra River Basin, Tibetan Plateau

Dynamics of the frozen ground are key to understand the changes of eco-environment in cold regions,especially for areas with limited field observations.In this study,we analyzed the spatial and temporal variations of the ground surface freezing and thawing indices from 1900 to 2017 for the upper Brahmaputra River(also called the Yarlung Zangbo River in China)Basin(UBRB),southwestern Tibetan Plateau,with the air freezing and thawing indices using the University of Delaware(UDEL)monthly gridded air temperature dataset.The abrupt change years for air freezing index(AH)and ground surface freezing index(GH)were detected in 1999 and 2002,respectively,and for both air thawing index(ATI)and ground surface thawing index(GTI)were 2009.With the air temperature rising at a rate of 0.006℃ per year over 1900-2017,the AH and GH decreased at a rate of-0.1℃ d per year,while the ATI and GTI increased at rates of 0.3 and 0.5℃ d per year before the abrupt change year,respectively;all changing trends of freezing/thawing indices increased after the abrupt year,which was-2.9,-0.8,7.3,and 21.7℃ d per year for the AH,GFI,ATI,and GTI,respectively.We utilized the surface frost number model to obtain the dynamics of the frozen ground over the UBRB.When the empirical coefficient of E was assigned to 1.2,the simulated frozen ground occupied about 53.2%of the whole UBRB in the 1990s,which agreed well with the existing permafrost map published in 1996.The area of frozen ground accounts for 51.5%-54.5%of the UBRB during 1900-2017.This result may facilitate further studies of the multi-interactions among the frozen ground and relevant eco-environment,such as the air-ground surface energy exchange,hydrological cycles,and changes of the active layer thickness over the UBRB.

基于地表冻结数模型的中国东北地区冻土分布模拟

Against the background of global warming, environmental and ecological problems caused by frozen ground degradation have become a focus of attention for the scientific community. As the temperature rises, the permafrost is degrading significantly in the frozen ground region of northeast China(FGRN China). At present, research on FGRN China is based mainly on data from meteorological stations, and the research period has been short.In this study, we analyzed spatial and temporal variation in the ground surface freezing index(GFI) and ground surface thawing index(GTI) from 1900 to 2017 for FGRN China, with the air freezing index(AFI) and air thawing index(ATI) using the University of Delaware(UDEL)monthly gridded air temperature dataset. The turning point year for annual mean air temperature(AMAT) was identified as 1985, and the turning point years for GFI and GTI were 1977 and 1996. The air temperature increased by 0.01 ℃ per year during 1900–2017, and the GFI and GTI increased at rates of –0.4 and 0.5 ℃ d per year before the turning point year;after the turning point, these rates were –0.7 and –2.1 ℃ d per year. We utilized a surface frost number model to study the distribution of frozen ground in FGRN China from 1900 to 2017.When the empirical coefficient E value is 0.57, the simulated frozen ground distribution is basically consistent with the existing frozen ground maps. The total area of permafrost in FGRN China decreased by 22.66×10^(4) km^(2) from 1900 to 2017, and the permafrost boundary moved northward with obvious degradation. The results of this study demonstrate the trend in permafrost boundary degradation in FGRN China, and provide basic data for research on the hydrological, climate, and ecological changes caused by permafrost degradation.

Topic-Feature Lattices Construction and Visualization for Dynamic Topic Number

The topic recognition for dynamic topic number can realize the dynamic update of super parameters,and obtain the probability distribution of dynamic topics in time dimension,which helps to clear the understanding and tracking of convection text data.However,the current topic recognition model tends to be based on a fixed number of topics K and lacks multi-granularity analysis of subject knowledge.Therefore,it is impossible to deeply perceive the dynamic change of the topic in the time series.By introducing a novel approach on the basis of Infinite Latent Dirichlet allocation model,a topic feature lattice under the dynamic topic number is constructed.In the model,documents,topics and vocabularies are jointly modeled to generate two probability distribution matrices:Documentstopics and topic-feature words.Afterwards,the association intensity is computed between the topic and its feature vocabulary to establish the topic formal context matrix.Finally,the topic feature is induced according to the formal concept analysis(FCA)theory.The topic feature lattice under dynamic topic number(TFL DTN)model is validated on the real dataset by comparing with the mainstream methods.Experiments show that this model is more in line with actual needs,and achieves better results in semi-automatic modeling of topic visualization analysis.