Modeling the crop transpiration using an optimality-based approach

Evapotranspiration constitutes more than 80% of the long-term water balance in Northern China. In this area, crop transpiration due to large areas of agriculture and irrigation is responsible for the majority of evapotranspiration. A model for crop transpiration is therefore essential for estimating the agricultural water consumption and understanding its feedback to the environment. However, most existing hydrological models usually calculate transpiration by relying on parameter calibration against local observations, and do not take into account crop feedback to the ambient environment. This study presents an optimality-based ecohydrology model that couples an ecological hypothesis, the photosynthetic process, stomatal movement, water balance, root water uptake and crop senescence, with the aim of predicting crop characteristics, CO₂ assimilation and water balance based only on given meteorological data. Field experiments were conducted in the Weishan Irrigation District of Northern China to evaluate performance of the model. Agreement between simulation and measurement was achieved for CO₂ assimilation, evapotranspiration and soil moisture content. The vegetation optimality was proven valid for crops and the model was applicable for both C ₃ and C ₄ plants. Due to the simple scheme of the optimality-based approach as well as its capability for modeling dynamic interactions between crops and the water cycle without prior vegetation information, this methodology is potentially useful to couple with the distributed hydrological model for application at the watershed scale.     

Modeling the crop transpiration using an optimality-based approach

Evapotranspiration constitutes more than 80% of the long-term water balance in Northern China. In this area, crop transpiration due to large areas of agriculture and irrigation is responsible for the majority of evapotranspiration. A model for crop transpiration is therefore essential for estimating the agricultural water consumption and understanding its feedback to the environment. However, most existing hydrological models usually calculate transpiration by relying on parameter calibration against local observations, and do not take into account crop feedback to the ambient environment. This study presents an optimality-based ecohydrology model that couples an ecological hypothesis, the photosynthetic process, stomatal movement, water balance, root water uptake and crop senescence, with the aim of predicting crop characteristics, CO₂ assimilation and water balance based only on given meteorological data. Field experiments were conducted in the Weishan Irrigation District of Northern China to evaluate performance of the model. Agreement between simulation and measurement was achieved for CO₂ assimilation, evapotranspiration and soil moisture content. The vegetation optimality was proven valid for crops and the model was applicable for both C ₃ and C ₄ plants. Due to the simple scheme of the optimality-based approach as well as its capability for modeling dynamic interactions between crops and the water cycle without prior vegetation information, this methodology is potentially useful to couple with the distributed hydrological model for application at the watershed scale.

     

地膜覆盖对土壤水热状况的影响及作物蒸腾量变化的研究

根据Philip、DeVries和Milly提出的土壤水热流动理论 ,建立了地膜覆盖冬小麦农田的土壤水热迁移的数值模型 ,上边界条件根据地膜的光学特性和气象参数确定 .模拟结果与实测结果符合较好 .在此基础上 ,通过逐步回归分析 ,对地膜覆盖情况下作物蒸腾量的变化原因进行了分析 .     

基于PI-演算的移动通信过程建模

针对现今移动通信中不同SP提供的业务无法互通的弊端,提出了用Web Service的思想来改进移动通信服务的方法。该方法主要以Internet为发展平台,把通信过程封装成多个Web Service,并用PI-演算来描述这些Web Service及服务组合,使每个通信过程的实现都是调用相关Web Service或Web Service组合。最后通过4个具体的实例说明了在移动通信过程中如何用PI-演算来建模Web Service。     

五效蒸发装置软测量模型的建立

从机理分析出发 ,结合多元线性回归法 ,建立了五效蒸发的数学模型 ,用现场数据对模型进行了校验 ,模型校验结果表明所建模型是合理和有效的     

离散非线性系统最优控制迭代算法的二维分析

针对具有终端约束的离散非线性最优控制问题，运用二维系统理论对动态系统优化和参数估计集成算法作了分析．从一个新的角度论证了该算法的最优性及收敛性，并给出了该算法一个易于验证的局部收敛的充要条件和全局收敛的一个充分条件．     

主动悬架耗散控制系统仿真与分析

建立主动悬架半车四自由度模型,应用耗散系统理论设计了主动悬架严格(Q,S,R)-耗散状态反馈控制器,使用Matlab/Simulink对系统模型进行仿真,使用时域和频域方法分析了车身垂直加速度、俯仰角加速度、悬架动行程和轮胎动位移4项指标,与被动悬架做了对比分析.仿真结果表明,使用严格耗散控制器的主动悬架在改善车辆乘坐舒适性和行驶平顺性方面效果明显.     

应用模拟退火算法进行二氧化碳提纯优化模型研究

高纯度二氧化碳用途很广，其纯化装置一提纯塔所提纯的二氧化碳纯度主要与进料纯度、进塔温度、塔顶压力、塔顶温度、塔釜加热温度、塔釜压力、塔釜温度7个因素有关．传统的方法用线性回归模型、对数回归模型建立二氧化碳纯度与这7个因素之间的关系，但拟合实际数据精度不高，影响模型的预测、控制能力．笔者建立了非线性数学模型，根据文献[2]中的数据，运用模拟退火算法得到二氧化碳提纯塔优化模型，其误差平方和小于文献[2]的同类误差，同时找到了最佳点，使成品二氧化碳质量分数达到99．5％以上．     

基于SolidWorks模型的虚拟装配模型转换和表达方法

为将SolidWorks装配模型转换为虚拟装配模型,提出把虚拟装配系统模型转换划分为零件模型转换和装配约束模型转换两部分.使用虚拟仿真标准格式OpenFlight数据库表达零件的层次化模型,采用面向对象的层次化模型表达零部件间的装配约束模型,零件模型和装配约束模型通过结点编号实现映射.在基于OpenGL Performer的虚拟装配系统中实现了装配模型的重构,实例研究表明该方法简单有效,具有可扩展性.     

平板式光生物反应器内有效光分布研究

为分析反应器内光能的分布对光合微生物生长的影响,完成自动光光生物反应器的优化,获得较高的CO2固定率,对利用平板式光生物反应器培养小球藻ZY-1的培养体系内的有效光的分布进行了分析,建立了单侧和双侧照明的平板式光生物反应器内的光分布模型,并将模型的计算值与有实际培养的试验值进行了比较.结果表明,所建的分布形摸型是合理的,与试验测试值基本相符,这为光生物反应器的合理优化提供了理论支撑.     

具有自适应调节功能的MANET与Internet互联

移动自组网(MANET)是由高度自主的移动节点组成的临时性自治系统,当其与Internet互联时,在保证互联性能的同时维持最低的网络整体开销是一大难题.如果通过移动节点信息来自适应设置网关通告报文的发送间隔,可以在保证良好的网络连接性的同时减少不必要的网关通告报文(Gateway Advertisement,GWADV)发送,在一定程度上降低网络整体开销.用NS2进行的仿真结果显示表明,提出的修改方案在改进互联性能的同时可以降低网络的整体开销.     

既有住宅建筑节能改造措施及节能减排效果——以夏热冬冷地区杭州市为例

分析了夏热冬冷地区既有住宅建筑节能改造的适用性措施及其节能减排效果.选取杭州市区典型既有住宅建筑为示例楼,并分析其实际热工性能;按照住宅建筑节能标准,从实际改造和热工模拟的角度分析变量的优化可能性,并提出7个切实可行的节能改造措施.采用反应系数法,动态能耗模拟评价各个措施的节能效果;根据节能效果,采用简化生命周期评价（LCA）方法,分析各个措施改造后CO2排放量.根据分析结果,提出优化节能改造方案.优化节能改造方案的分析结果显示,通过节能改造,优化杭州既有住宅建筑的热工性能,非常有助于节能和降低CO2排放     

NPV risk simulation of an open pit gold mine project under the O'Hara cost model by using GAs

This paper analyzes an open pit gold mine project based on the O'Hara cost model. Hypothetical data is proposed based on different authors that have studied open pit gold projects, and variations are proposed according to the probability distributions associated to key variables affecting the NPV, like production level, ore grade, price of ore, and others, so as to see what if, in a gold open pit mine project of 3000 metric tons per day of ore. Two case scenarios were analyzed to simulate the NPV, one where there is low certainty data available, and the other where the information available is of high certainty. Results based on genetic algorithm metaheuristic simulations, which combine basically Montecarlo simulations provided by the Palisade Risk software, the O'Hara cost model, net smelter return and financial analysis tools offered by Excel are reported, in order to determine to which variables of the project is more sensitive the NPV.