高山峡谷地区森林流域分布式降雨-径流模型的构建与验证

根据岷江上游杂谷脑河流域典型的高山峡谷地区主要水文特点,选择通用性较强的水文过程模式,构建高山峡谷地区森林流域分布式降雨-径流过程模型,避免过多复杂的区域性模型参数率定,保证模型在相似地区的可移植性;并选择杂谷脑水文站上游地区进行降雨-径流过程模拟,得到1999年和2000年模拟时段长度为1000 h的两个径流过程,对模拟与实测的径流过程、累积径流量、洪峰流量与峰现时间等进行比较,其拟合效果较好.该模型结构简单,引入的经验参数较少,可推广应用到其它尺度流域.     

基于GreenLab的油松结构-功能模型

 植物结构-功能模型(Functional-structural models, FSMs)将结构模型与过程模型结合起来, 用以描述环境机制驱动的植物生长, 输出植物的三维结构。GreenLab是一个近年来不断发展着的基于源-汇关系的通用植物结构-功能模型, 它多应用于农作物, 在树木方面的应用还很少。该文以幼龄油松(Pinus tabulaeformis)为研究对象, 首次将GreenLab模型应用到虚拟树木生长的研究中。采用破坏性取样, 实测了9株油松幼树的形态结构、拓扑结构和器官生物量信息, 根据拓扑编码体系组织数据。模型的直接参数是通过实测数据获得的, 隐含参数是利用非线性最小二乘法拟合反求获得的。对模型的假设进行了验证, 并对模型的模拟效果进行了评估, 结果表明: 节间总鲜质量、树木叶总鲜质量、节间鲜质量、节间长度观测值和模型模拟值建立的回归方程的决定系数在0.78~0.91之间, 因此该模型较真实地反映了油松的结构和生长过程。提出的树木结构和生物量测量及编码方法, 可作为针叶树建立结构-功能模型的参照。     

利用回归模型筛选出近天然的抗原-抗体对接模拟结构

在抗原-抗体分子对接模拟所生成的大量计算生成构象中筛选出近天然结构,即接近真实情况的抗原-抗体结合模式。借鉴QSAR原理,定义抗原-抗体接触面描述符并利用Discovery Studio 4.5软件平台计算出各对接模拟构象的接触面描述符和能量参数。构造训练集数据进行回归分析,建立预测对接模拟构象是否是近天然结构的数学模型。通过测试集和实际应用情况检验该数学模型。通过回归分析所建立的数学模型能够在成百上千的抗原-抗体对接模拟构象中有效筛选出其中的近天然结构,在测试集验证和4G7抗体结合模式预测应用中具有良好的表现,验证了该数学模型的有效性和实用性。经验性的抗原-抗体接触面特征如氢键密度、氨基酸对偏好性指数等以及能量参数能够共同有效表征近天然结构,所建立的数学模型有效增强了通过分子对接预测抗原-抗体结合模式的可行性。     

森林-农业景观格局变化的社会-生态系统模拟模型方法进展

社会-生态系统（SES）模拟模型是景观格局分析和决策的有效工具,能表征景观格局变化的社会-生态效应及景观决策的复杂反馈机制。文献综述了森林-农业景观格局的SES模型方法进展发现：（1）多数模型对景观过程与社会经济决策的反馈关系分析不足;（2）应集成多种情景模拟和景观效应分析方法,完善现有SES模型的理论方法基础;（3）通过集成格局优化模型和自主体模型会有效改进SES模型功能,具体途径包括：集成情景-生态效应的景观格局模拟方法、完善景观决策的理论基础、加强集成模型的不确定性分析、降低模型复杂性和综合定性-定量数据等。研究结果有助于理解多尺度森林-农业景观格局在社会-生态系统中的重要作用,能更好地支持跨学科集成模型开发与应用。     

山地梨枣树耗水特征及模型

由于枣树树龄、品种、冠层形态、下垫面以及枣树种植区气象条件不同,导致榆林地区枣树耗水规律研究缺乏系统性.本文利用HYDRUS-1D数学模型对枣树耗水规律进行了研究.2008-2010年通过对榆林米脂县不同树龄山地梨枣树叶面积指数、根系分布规律,作物系数的研究,结合HYDRUS-1D模型预测所需土壤、气象等参数的测定,对山地梨枣树土壤水分动态进行了模拟,并对土壤水分模拟结果与实测值进行拟合,反推出模型计算所需的消光系数及土壤水分胁迫系数等参数.结果表明:HYDRUS-1D模型能够很好模拟该地区梨枣树土壤水分动态变化过程,该地区成年(8龄)梨枣树从发芽开始到梨枣收获期结束共耗水267 mm.     

WOFOST模型在内蒙古河套灌区模拟玉米生长全程的适应性

在河套灌区引入成熟的作物模型并进行适应性验证,可为进一步开展玉米生长监测及估产提供依据和基础。本文利用河套灌区巴彦淖尔农业气象试验站2012年玉米观测数据,结合当地气象、土壤资料对荷兰瓦赫宁根大学开发的WOFOST模型进行参数校准,并利用2013年玉米观测数据和2001—2011年农业气象观测资料对模型的区域适用性进行验证,获得了玉米的基本作物参数,包括各发育阶段比叶面积、最大CO2同化率、单叶光能利用率等。结果表明:通过校准作物参数,WOFOST模型可以较好地模拟LAI扩展、生物量的动态积累过程,LAI、各器官生物量及最终产量的模拟值与实测值吻合较好;独立样本检验中,模型模拟LAI的绝对偏差平均值为0.75,叶生物量、茎生物量、贮存器官生物量、地上部总生物量、产量的归一化均方根误差分别为33%、26%、17%、18%和13%;模拟2001—2011年玉米产量的归一化均方根误差为7.5%。参数校准后的模型对LAI、各器官生物量、产量的模拟结果较为符合实际,WOFOST模型能够适用于河套地区玉米生产过程生理、生态因子诊断、评估等。     

Kitasatospora sp. MY5-36产ε-聚赖氨酸分批补料发酵动力学

以北里孢菌(Kitasatospora sp.)MY 5-36为供试菌株,对ε-聚赖氨酸分批补料发酵动力学模型进行研究。建立了该菌株发酵合成ε-聚赖氨酸的菌体生长、产物合成和总糖消耗的动力学模型,并通过Origin 8.1软件对模型参数进行非线性拟合。结果表明:菌体量和聚赖氨酸的产量分别为16.25和13.15 g/L,产物合成与菌体生长的关系为部分耦联型。经验证,预测值与实验值有良好的拟合性,拟合度分别为0.999、0.995和0.992,说明所构建模型能够较好地反映ε-聚赖氨酸分批补料发酵过程。     

干旱条件下夏玉米地-气温差的影响因素及其模拟

地-气温差指标表征作物水分亏缺状况已经被广泛研究,但地-气温差随作物生育进程的变化特征及其影响因子的观测研究仍较少,制约着地-气温差的准确模拟.基于夏玉米2014年三叶期和2015年拔节期的5个灌溉水分控制试验资料的研究表明: 随着夏玉米生育进程的推进,土壤水分的变化显著影响了夏玉米农田的地-气温差,土壤水分亏缺越严重,地-气温差越高.在整个水分处理期间,归一化植被指数是地-气温差的主要影响因子且两者呈显著的线性关系,但不同生育期地-气温差还受其他因子的影响:三叶期后受冠层吸收光合有效辐射比影响且呈显著的线性关系,三叶期至拔节期则受土壤相对湿度和空气相对湿度的影响且呈显著的线性关系.在此基础上,基于2014年试验资料建立了夏玉米全生育期地-气温差模拟模型、营养生长期地-气温差模拟模型和生殖生长期地-气温差模拟模型,并利用2015年夏玉米拔节期5个灌溉水分控制试验资料进行了模型验证,结果表明,夏玉米全生育期地-气温差模型可以解释2015年地-气温差变异的63%,但地-气温差分生育期模拟模型,即营养生长期地-气温差模拟模型和生殖生长期地-气温差模拟模型综合的模拟结果则可解释2015年地-气温差变异的79%.研究结果为基于地-气温差的作物干旱指标定量评估作物干旱提供了依据.     

芦苇湿地多时空尺度蒸散模拟研究进展

湿地蒸散是湿地水分损失的主要途径,由于其对气候变化的高度敏感性和重要的反馈作用而倍受关注。湿地蒸散过程可以分为叶片、植株、冠层、景观至区域等多种尺度,如何实现不同时空尺度的过程和参数耦合成为湿地蒸散研究的重点和难点。本文回顾了湿地蒸散模拟研究的发展历程,着重总结了芦苇湿地蒸散监测及模拟方面的技术和方法,并从不同时间尺度(日、月、年)和不同空间尺度(叶片、植株、冠层、区域)以及实现不同时空尺度拓展的关键技术研究等方面进行归纳和总结,探讨了今后的研究重点。实现不同时空尺度的芦苇湿地蒸散过程的准确模拟,关键在于大气-植被-土壤界面的参数耦合,而目前针对不同尺度的芦苇湿地蒸散参数化研究很少,因此,有必要探讨适合芦苇湿地多尺度蒸散模拟及参数化方法,为芦苇湿地蒸散评估模型的选择提供理论支持。     

杭嘉湖地区淹水稻田氮素径流流失负荷估算

通过大田试验、定点观测等方法对现有的关于长江三角洲平原地区水田降雨径流产生模型进行验证,发现该模型在考虑排水堰的影响之后,基本能够模拟杭嘉湖平原水网区水田降雨径流产生过程,误差在-19.9%～+18.0%之间,同时提出了淹水稻田降雨径流氮素浓度模型（R=0.948）,从而得到了该地区淹水稻田氮素径流流失负荷模型.在此基础上,搜集了该地区水稻田氮肥施用情况、30年逐日降雨量、1∶250000地形图、土地利用现状图和水系图等资,利用GIS技术对该地区淹水稻田氮素的径流流失负荷以及空间分布进行了估算和分析.结果表明,该地区淹水稻田氮素径流流失负荷平均高达35.26 kg N·hm^-2,约占当季水稻氮素施用量的12.69%,而且在空间上存在着明显的差异,安吉、余杭等地区氮素流失负荷和流失率明显高于其它地区,海宁地区的流失情况也较为严重.     

基于模型的景观格局与生态过程研究

景观格局与生态过程关系的研究是景观生态学的主要特色和理论核心之一。模型可以充分利用实验和观测数据并综合不同时间和空间尺度上的信息提炼规律或揭示内在机制,模拟景观格局与生态过程的动态与相互关系,成为景观生态学研究的有力工具。结合研究实例,总结了基于模型的景观格局研究、生态过程研究和格局-过程关系研究的发展现状和薄弱环节,同时探讨了通过构建耦合模型研究格局-过程相互关系的途径。总结了景观模型研究亟待发展的领域与发展趋势。     

流域水文模型在面源污染模拟与管控中的应用研究进展

面源污染是影响流域水环境和水安全的重要污染来源,对其进行有效防控需要对其负荷以及防控措施效果进行科学高效精准的预测。流域水文模型(Hydrological Simulation Program-FORTRAN,HSPF)具有突出的综合性和灵活性,是面源污染模型的典范。近年来,HSPF模型应用于我国流域面源污染相关的研究和实践有了飞速发展,但同样也面临着模型机理和参数本地化、模型构建精细化、模型结构不确定性较大等方面的挑战。围绕该模型在面源污染模拟与管控中的研究进展,对其在变化环境下的模拟方法和成果,以及应对参数识别、不确定性分析、措施效果评估和总量控制的思路和方法等方面进行了总结,并分析了现代化环境模拟形势下HSPF模型的延伸发展。结合模型相关研究的总结,强调了面向我国流域特色的本地化模型改进、服务河长制精细监管的大尺度精细化模拟、以及模型与大数据统计及人工智能耦合的互馈集合模拟等后续研究是需要重点关注的发展动向。     

人眼房水动力学系统的建模与仿真方法研究

为从宏观上应用工程方法进一步研究房水运行机理,提出了人眼前节房水流动系统的动力学仿真模型。依据目前眼科界较为公认的房水运行和眼压反馈机制建立系统构架,基于对眼科解剖学与生理学相关理论的分析、流体力学基本原理和临床参数进行系统辨识与参数确定。运用数字仿真的方法分剐在正常生理平稳状况和激发试验状况下对模型进行了仿真运行,获得了和临床结论较为一致的结果。能较好地模拟房水运行机制,在与临床可测量参数一致的同时能获得一些不易测量的参数,为研究房水动力学提供依据。     

Development and testing of a chemical mechanism for atmospheric photochemical transformations of 1,3-butadiene

1,3-Butadiene (BD) in the atmosphere is a highly reactive hazardous air pollutant, which has a short lifetime and is quickly transformed to reaction products, some of which are also toxic. The ability to predict exposure to BD and its' products requires models with chemical mechanisms which can simulate these transformations. The atmospheric photochemical reactions of BD have been studied in the University of North Carolina Outdoor smog chamber, which has been used for over 30 years to test photochemical mechanisms for air quality simulation models for ozone. Experiments have been conducted under conditions of real sunlight and realistic temperature and humidity to study the transformations of BD and to develop and test chemical mechanisms for the simulation of these processes. Experimental observation of time-concentration data of BD decay and the formation of many products is compared to simulation results. This chemical mechanism can be incorporated into air quality simulation models which can be used to estimate ambient concentrations needed for exposure estimates.     

Model parameterization to represent processes at unresolved scales and changing properties of evolving systems

Modeling has become an indispensable tool for scientific research. However, models generate great uncertainty when they are used to predict or forecast ecosystem responses to global change. This uncertainty is partly due to parameterization, which is an essential procedure for model specification via defining parameter values for a model. The classic doctrine of parameterization is that a parameter is constant. However, it is commonly known from modeling practice that a model that is well calibrated for its parameters at one site may not simulate well at another site unless its parameters are tuned again. This common practice implies that parameter values have to vary with sites. Indeed, parameter values that are estimated using a statistically rigorous approach, that is, data assimilation, vary with time, space, and treatments in global change experiments. This paper illustrates that varying parameters is to account for both processes at unresolved scales and changing properties of evolving systems. A model, no matter how complex it is, could not represent all the processes of one system at resolved scales. Interactions of processes at unresolved scales with those at resolved scales should be reflected in model parameters. Meanwhile, it is pervasively observed that properties of ecosystems change over time, space, and environmental conditions. Parameters, which represent properties of a system under study, should change as well. Tuning has been practiced for many decades to change parameter values. Yet this activity, unfortunately, did not contribute to our knowledge on model parameterization at all. Data assimilation makes it possible to rigorously estimate parameter values and, consequently, offers an approach to understand which, how, how much, and why parameters vary. To fully understand those issues, extensive research is required. Nonetheless, it is clear that changes in parameter values lead to different model predictions even if the model structure is the same.     

A mathematical model and computer simulation study of insulin receptor regulation

A homeomorphic mathematical model of cell surface insulin receptor regulation is developed. The overall structure of the model is based on molecular mechanisms suggested by in vivo and in vitro experimental evidence from many different cell types. Model parameters correspond to cellular processes which are constrained by known boundry value conditions. As an example, computer simulation results are compared with published data from BC3H-1 myocytes in culture. With appropriate parameter choice, this model is able to simulate data from other cell types. Cellular processes which are explicitly represented in the model include: bound and unbound receptor endocytosis, receptor recycling, intracellular receptor degradation, and state-dependent receptor synthesis. Most of these processes are represented as first-order events. Using more complex representations of the model structure with higher order rate constants or saturable pathways does not qualitatively improve simulation results. Simulations are able to reproduce ligand-induced down and up regulation of receptors as well as the initial spontaneous display of surface insulin receptors. To demonstrate the behavior of our model and illustrate its utility for explaining insulin receptor regulation for a variety of conditions, simulations for which experimental data is unavailable for direct comparison are also shown. We believe the structure of our model is sufficient to explain insulin receptor regulation in a wide variety of cell types. In addition our model may aid in understanding the receptor component of insulin resistance (decreased sensitivity or responsiveness to insulin) seen in pathological states such as obesity and diabetes mellitus. Finally, this model may be applicable to the study of the regulation of other polypeptide hormone receptors.     

A mathematical model and computer simulation study of insulin sensitive glucose transporter regulation

A mathematical model of insulin sensitive glucose transporter regulation is developed. Model structure is based on experimental evidence from adipocytes and myocytes. Model parameters correspond with known cellular processes. As an example, computer simulation results are compared with data from rat adipocytes. Cellular processes explicitly represented in the model include state-dependent glucose transporter synthesis and degradation rates, insulin sensitive glucose transporter translocation rates, and a glucose transporter endocytosis rate. Most of these processes are represented as first-order events. Using more complex representations of the model structure (e.g. higher order rate constants or saturable pathways) or alternative structures did not result in qualitatively better results. The model is able to accurately simulate the insulin sensitive, insulin concentration dependent, reversible translocation of glucose transporters observed in normal adipocytes. The model is also able to accurately simulate the changes in regulation of glucose transporter translocation observed with increases in cell surface area. Finally, the model can simulate pathogenic states which induce impairment of glucose transporter regulation (e.g. altered glucose transporter regulation in adipocytes from rats on high fat diets, rats with streptozotocin induced diabetes, and fasted rats). Since the structure of our model is sufficient to explain glucose transporter regulation in both normal and pathological states, it may aid in understanding the post-receptor components of insulin resistance (decreased sensitivity or responsiveness to insulin) seen in pathological states such as obesity and diabetes mellitus.     

大兴安岭林区10小时时滞可燃物湿度的模拟

随着森林防火预报精细化的需求,小时尺度可燃物湿度的准确模拟成为火险预报的关键。利用2010年8月连续无降雨天气条件下我国大兴安岭林区10h时滞可燃物湿度和相应气象因子的半小时动态观测资料,从可燃物的失水和吸水过程对目前广泛使用的Fosberg模型和Van Wagner模型进行评估,进而发展了准确模拟10h时滞可燃物失水和吸水过程的可燃物湿度模型。结果表明:Fosberg模型对10h时滞可燃物的失水过程模拟较好(R²=0.96,P<0.01),而Van Wagner模型对10h时滞可燃物的吸水过程模拟较好(R²=0.83,P<0.01),但均不能独立地准确模拟10h时滞可燃物的湿度变化。通过分析可燃物失水与吸水过程,考虑可燃物在静风条件下的水汽交换,优化了Van Wagner模型参数,建立了综合反映可燃物失水与吸水过程的10h时滞可燃物湿度模型。据比较,该模型可准确地模拟10h时滞可燃物的湿度变化(R²=0.88,P<0.01),可为精细化火险预报提供技术支撑。     

A review of rhizosphere carbon flow modelling

Rhizosphere processes play a key role in nutrient cycling in terrestrial ecosystems. Plant rhizodeposits supply low-molecular weight carbon substrates to the soil microbial community, resulting in elevated levels of activity surrounding the root. Mechanistic compartmental models that aim to model carbon flux through the rhizosphere have been reviewed and areas of future research necessary to better calibrate model parameters have been identified. Incorporating the effect of variation in bacterial biomass physiology on carbon flux presents a considerable challenge to experimentalists and modellers alike due to the difficulties associated with differentiating dead from dormant cells. A number of molecular techniques that may help to distinguish between metabolic states of bacterial cells are presented. The calibration of growth, death and maintenance parameters in rhizosphere models is also discussed. A simple model of rhizosphere carbon flow has been constructed and a sensitivity analysis was carried out on the model to highlight which parameters were most influential when simulating carbon flux. It was observed that the parameters that most heavily influenced long-term carbon compartmentalisation in the rhizosphere were exudation rate and biomass yield. It was concluded that future efforts to simulate carbon flow in the rhizosphere should aim to increase ecological realism in model structure. This revised version was published online in June 2006 with corrections to the Cover Date.