Some questions about landscape modlling

ＭｏｄｅｌｌｉｎｇｅｃｏｓｙｓｔｅｍｓｈａｓｂｅｅｎｄｏｎｅｂｙｍａｎｙｐｅｏｐｌｅｓｉｎｃｅｔｈｅｉｎｉｔｉａｌｌａｕｎｃｈｇｉｖｅｎｂｙＯｄｕｍ (Ｏｄｕｍ ,1983) .Ｂｕｔｍｏｄｅｌｌｉｎｇｔｈｅｆｕｎｃｔｉｏｎｉｎｇｏｆｌａｎｄｓｃａｐｅｓｉｓｎｏｔｓｏｆｒｅｑｕｅｎｔａｎｄｌａｎｄｓｃａｐｅｅｃｏｌｏｇｙｉｓｓｏｙｏｕｎｇｔｈａｔｔｈｅｔｙｐｅｏｆｍｏｄｅｌｗｈｉｃｈｈａｓｔｏｂｅｃｈｏｓｅｎｉｓｎｏｔａｌｗａｙｓｅｖｉｄｅｎｔ.Ａｆｉｒｓｔｃｏｎｓｔｒａｉｎｔｉｓｔｈａｔｔｈｅｍｏｄｅｌｍ…     

Exergy and ecological modelling of lake environment

１ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｃｒｅａｓｉｎｇｌｙｓｅｒｉｏｕｓｌａｋｅｅｕｔｒｏｐｈｉｃａｔｉｏｎｈａｓｂｅｃｏｍｅａｇｌｏｂａｌｅｎｖｉｒｏｎｍｅｎｔａｌｐｒｏｂｌｅｍａｎｄｄｒａｗｎｇｒｅａｔａｔｅｎｔｉｏｎ．ＩｎＣｈｉｎａ，ｍａｎｙｌａｋｅｓ...     

Twin–twin transfusion syndrome: mathematical modelling

Twin–twin transfusion syndrome (TTTS) represents a pregnancy complication with a high risk for perinatal mortality and postnatal morbidity. Mathematical models have been utilized to examine the mechanisms of disease and potential treatment modalities. We developed four consecutive models based on pathophysiology mechanisms. Conceptually, these models remained simple, but with increased complexity in details. We present our models tutorially with the necessary equations expressed in words. The aetiology of TTTS was related to AV anastomoses from donor to recipient and their growth commensurate with placental growth. We assessed that natural growth of placenta and foetuses causes the diameter and length of the AV, as well as the AV's pressure gradient, to increase proportional to gestational age. The AV transfusion then increases faster than natural foetal growth. A progressively increasing discordance subsequently develops, not compensated for by foetal growth. A simulation is performed to show how this discordance in blood volumetric development causes successive discordances in other functions, particularly renal, circulatory, and cardio-vascular, resulting in disease progression to the various stages of TTTS. In conclusion, mathematical modelling of TTTS has provided an understanding of the sequence of events that leads to the various presentations of TTTS stages as well as the efficacy of therapies. Copyright © 2008 John Wiley & Sons, Ltd.     

Basic Lagrangian and Eulerian modelling of atmospheric diffusion

This note initially considers the Lagrangian approach and compares the case of the instantaneous source with the continuous one. Then, the Eulerian approach is discussed and it is shown that the main models appearing in the literature, from the telegraph, to the pseudo-spectral and the K-model are all different expressions of a more general integral differential equation proposed by Roberts.     

城市降雨径流模型的参数局部灵敏度分析

运用Morris筛选法对城市降雨径流模型SWMM的水文水力模块的相关参数进行局部灵敏度分析,以便对模型灵敏参数识别和不确定性分析.结果表明,影响3场降雨径流深的最灵敏度参数均为不透水率,灵敏度分别是0.88,0.98和0.43.影响峰值流量的灵敏参数因不同雨强的降雨场次存在波动,雨强最大的降雨最灵敏参数为管道曼宁糙率,雨强最小的降雨最灵敏参数为无低洼地不透水区所占百分比.不同降雨强度SWMM模型水文水力模块的灵敏参数有所差异,尤其是下渗率相关的参数.     

Dispersion modelling of nitrogen oxides in the United Kingdom

This paper describes the construction and application of an Eulerian-dispersion model for the calculation of NO₂ and NO_x concentrations in the U.K. Model results are compared with measurements from 44 U.K. sites. The sensitivity of the model results to chemical and dispersion parameterisations is assessed. The model is also used to verify the validity of ‘instantaneous mixing’ assumptions used in trajectory models. Finally, the distribution of ground-level NO_x concentrations from power stations, motor vehicles and other stationary sources is calculated across the U.K., including a preliminary assessment of the possible contribution from natural sources.     

Using non-equilibrium biosorption column modelling for improved process efficiency

An unsteady-state biosorption column model in one space variable is considered in this paper. The theoretical study is motivated by the need for predicting the dependent variables of biosorption columns for removal of heavy metals from wastewater, which is potentially an important technology in cleaner production. Pollutant concentrations in the bulk phase, in the liquid filling the pores and in the solid biomass along the axial coordinate of the column were evaluated for a wide range of physical and chemical parameters of the global process. In particular, the assumption of instantaneous chemical reactions is replaced by a more realistic expression taking into account chemical kinetics and fluid advection time scales separately. The resulting system of partial differential equations was solved by means of a reliable numerical algorithm based on the method of lines. The data obtained using the model described in this paper are compared with published experimental data and an estimation of the increased efficiency is made.     

Uncertainty in dispersion modelling and urban air quality mapping

The ADMS-urban atmospheric dispersion modelling system has been applied to review of air quality in central London in 1996/1997 and assessment of future air quality against air quality objectives in 2005. Model performance is assessed by in situ validation against monitoring data. This case study illustrates how scientific uncertainty needs to be considered when using model output in such a policy context. Model precision, carefully defined, is ±10% with bias between 0 and +12% (model over-prediction) for annual mean nitrogen dioxide and respirable particulate (PM₁₀) concentrations and for the 90th percentile of daily mean PM₁₀. As expected, the model is less accurate for the maximum and 99.8th percentile of hourly mean nitrogen dioxide concentrations and for total NO_x. We propose probabilistic mapping techniques should be used to formalise and clarify how uncertainty is translated into the definition of an Air Quality Management Area (AQMA) on a map. This also identifies the extent to which air quality objectives have been defined for which current dispersion model performance is inadequate. It is recommended that the capabilities of modelling alongside measurement need to be considered at an early stage in the formulation of future air quality management policy.     

Studies on crop growth modelling and simulation models in China

There is a close relationship between agricultural production and environmental meteorological conditions. In the study of the correlation between them, the simulation models are paid more attention to the crop growth. In this paper the development of the studies on the crop growth dynamic simulation model in China is briefly reviewed. The relationships between meteorological conditions and each process of crop growth (such as photosynthesis, respiration, accumulation and distribution of assimilation products and growth of leaf area) are studied and simulated basing on the results from field experiments. Preliminary models for rice, wheat, maize and soybean have been developed, and some investigations about modelling methods, procedures and parameters in simulation models are made.     

基于土地利用的中国城镇化SD模型与模拟

中国正处在快速推进的城镇化进程中,耕地与林地、牧草地和水域等生态用地将如何变化,以及建设用地是否仍将快速增长?这不仅是国家宏观政策制定者关心的问题,也是广大学者和普通民众面临的具体问题。通过构建基于土地利用的中国城镇化系统动力学（System dynamics,SD）模型,尝试对上述问题作出分析。研究结果表明：（1）本文构建的模型是有效的,具备可靠性和稳定性。（2）若要保持国家耕地保有量不少于18.25亿亩,到2050年需补充83.17万~412.67万hm²耕地资源。（3）到2050年,如果中国城镇化水平达到78%左右,建设用地总量将达到4007.29万~4214.25万hm²,较2020年净增加了155.87万~342.88万hm²。（4）2020—2050年生态用地数量表现为先增加后减少,其中,林地显著增加,牧草地减少,水域略有增加。研究成果可为全国国土空间规划多方案模拟、评估和决策提供科学服务。     

Mapping and modelling of changes in agricultural intensity in Europe

Spatial maps of agricultural intensity are needed for analyses of environmental issues, including biodiversity changes. We present a method to produce such maps for Europe. While most studies beyond farm level focus on land cover change only, this paper focuses on spatial variation in land use intensity and its dynamics.Our method defines agricultural land use intensity in terms of nitrogen input. For arable land, it combines field observations with administrative-level statistics to assess probability of occurrence for three land use intensity classes. For grassland, it uses maps of livestock density to assess probability of occurrence for two intensity classes. Agricultural land is spatially allocated to intensity classes using an algorithm that downscales intensity changes simulated with an agricultural economic model.Our results are 1 km² resolution maps of classified agricultural land use intensity in the year 2000. We illustrate the method by exploring changes in the spatial pattern of land use intensity for a financial policy reform scenario in the year 2025. Results indicate spatial heterogeneity in land use intensity across European countries, including large differences in intensity between countries, between regions, but also within regions.Our method could be improved with smaller-resolution agricultural statistics and broader intensity indicators.     

Mathematical and experimental modelling of phenol degradation in air-lift bioreactors

The aim of this paper is to show the possibility of eliminating phenol from wastewater via biodegradation. In the first part, the kinetics of bacterial degradation (Alcaligenes xylosoxidans ssp denitrificans and Xanthomonas maltophilia) of phenol is discussed. Haldane kinetic equations better fit the experimental kinetic data than does using the Monod equation. The second part of the paper is devoted to mathematical modelling of air lift bioreactors to calculate the degradation of phenol. The calculations show the fractional conversion of phenol is over than 99% using an air lift 2 m reactor.     

Integrated scenario modelling of energy,greenhouse gas emissions and forestry

Preventing dangerous climate change requires actions on several sectors. Mitigation strategies have focused primarily on energy, because fossil fuels are the main source of global anthropogenic greenhouse gas emissions. Another important sector recently gaining more attention is the forest sector. Deforestation is responsible for approximately one fifth of the global emissions, while growing forests sequester and store significant amounts of carbon. Because energy and forest sectors and climate change are highly interlinked, their interactions need to be analysed in an integrated framework in order to better understand the consequences of different actions and policies, and find the most effective means to reduce emissions. This paper presents a model, which integrates energy use, forests and greenhouse gas emissions and describes the most important linkages between them. The model is applied for the case of Finland, where integrated analyses are of particular importance due to the abundant forest resources, major forest carbon sink and strong linkage with the energy sector. However, the results and their implications are discussed in a broader perspective. The results demonstrate how full integration of all net emissions into climate policy could increase the economic efficiency of climate change mitigation. Our numerical scenarios showed that enhancing forest carbon sinks would be a more cost-efficient mitigation strategy than using forests for bioenergy production, which would imply a lower sink. However, as forest carbon stock projections involve large uncertainties, their full integration to emission targets can introduce new and notable risks for mitigation strategies.     

Transient mathematical modelling of a fluidized bed incinerator for sewage sludge

Sewage sludge production has been increasing due to the growth of urban wastewater treatment plants. According to the enforcement of current environmental regulations, many efforts must be done to manage the large amount of generated sludge. Incineration is one potential treatment process.As far as control, design and operational guidance of processes are concerned, a successful simulation work may significantly reduce the efforts in experimental study.In this goal, a real-time simulator has been developed to describe bubbling fluidized bed incineration of sewage sludge.In the present work, details of the mathematical model are presented. The two main particularities are the buffer zone characteristics in one hand, and on the sewage sludge pyrolysis, supposed to be flash on the other one. The model results are partially validated by comparison with experimental data issued from the literature. An example of a possible scenario is given.     

Mesoscale meteorological modelling for Hong Kong-application of the MC2 model

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｉｓｐａｐｅｒｃｏｎｃｅｒｎｓｔｈｅａｄａｐｔａｔｉｏｎａｎｄａｐｐｌｉｃａｔｉｏｎｏｆａｍｅｓｏｓｃａｌｅｍｅｔｅｏｒｏｌｏｇｉｃａｌｍｏｄｅｌｆｏｒｇｅｎｅｒａｔｉｎｇｔｈｅｗｉｎｄｆｉｅｌｄｓａｎｄｏｔｈｅｒｍｅｔｅｏｒｏｌｏｇｉｃａｌｐａｒａｍｅｔｅｒｓｆｏｒｆｕｔｕｒｅｓｔｕｄｉｅｓｏｆａｉｒｐｏｌｌｕｔｉｏｎｉｎｔｈｅｃｏｍｐｌｅｘｔｅｒｒａｉｎｏｆＨｏｎｇＫｏｎｇＳｐｅｃｉａｌＡｄｍｉｎｉｓｔｒａｔｉｖｅＲｅｇｉｏｎ (ＨＫＳＡＲ) .Ｔｈｅｍａｉｎａｒｅａ…     

Practical dispersion modelling for buoyant elevated sources in a tropical region

The worst-case meteorological scenarios for the air pollution impact of coal-fired power stations located in tropical Australia are usually those of convective or seabreeze states. Under such conditions maximum hourly ground-level concentrations occur within 5 km of typical elevated sources and are potentially important unless either low sulphur coal is burnt (the usual situation for Australian coals) or restrictions are placed upon neighbouring land use. In such conditions even slightly complex surrounding terrain can cause major changes in surface and lower-level wind and turbulence characteristics, although the resultant effects on ground-level concentrations are probably relatively small. The monitoring data bases of an inland and a coastal power station in tropical Queensland give similar qualitative results to recent EPRI studies. Concurrent detailed meteorological measurements show that convective scaling techniques order both data sets in a satisfactory manner. The convective dispersion model of Spillane (1985, CSIRO internal report) has also shown more predictive skill than conventional approaches and emphasizes the importance of gathering vertical velocity statistics for most sites. Some of the forthcoming developments in related Australian dispersion work are outlined.     

Measurement and modelling of cloudwater deposition to a snow-covered forest canopy

Measurements are presented of the flux of cloud droplets, as a function of particle size to a forest canopy (Sitka spruce) before and after a light snowfall. The results are compared to the predivtions of the model of Slinn. Good agreement is found provided that appropriate values for the effective target diameter are chosen, both before and after the snowfall. It is shown that the snowfall results in a considerable reduction in the flux of cloud water to the forest canopy (by a factor of about 2). The snow reduces the surface roughness of the canopy but the most important effect is that it increases the effective target diameter for the droplets impacting on the tree. This effect may considerably reduce the deposition of phytotoxic chemical species to forests at high altitude where snow cover and low cloud are common in winter.     

Numerical modelling of electrohydraulic free-forming and die-forming of DP590 steel

Electrohydraulic forming (EHF) is a high energy rate forming process in which the strain rate in the sheet metal can vary from 5 × 10² to 10⁵ s⁻¹ depending on various factors. Several mechanisms have been reported to cause an improvement in formability in EHF such as material deformation mechanisms, inertial effects and the dynamic impact of the sheet against the die. EHF is a complex high speed forming process and experimental work alone is not sufficient to properly understand this process. To understand the variation of some influential variables in EHF, electrohydraulic die-forming (EHDF) and free-forming (EHFF) of DP590 dual phase steel were simulated in ABAQUS/Explicit by considering the fluid/structure interactions. Three-dimensional finite element simulations were conducted by modelling the water with Eulerian elements with a view to investigating the effect of released energy on the sheet deformation profile history, strain distribution, loading path and damage accumulation type. The Johnson–Cook constitutive material model was used to predict the sheet behaviour and the parameters in this model were calibrated based on experimental test results available for DP590 at various strain rates. The Johnson–Cook phenomenological damage model was also used to predict the ductile failure (damage accumulation) in both EHDF and EHFF. Predicted final strain values and damage accumulation type showed good agreement with the experimental observations.