SCEM-UA优化算法在水文频率分析中的应用

【目的】将SCEM-UA优化算法应用于水文频率分布曲线优化适线法中,并与传统适线法进行对比,为水文频率分析提供方法支持。【方法】采用基于SCEM-UA优化算法的优化适线法,对长江流域宜昌水文站1974-2003年年最大流量数据进行水文频率分析,确定其理论频率曲线统计参数,计算离差绝对值和与离差平方和;利用同组数据,采用矩法、权函数法、概率权重矩法对其进行水文频率分析,并将结果与SCEM-UA优化算法所得结果进行对比。【结果】SCEM-UA算法离差绝对值和与离差平方和分别为23 481和33 734 707,均小于其余3种方法;利用SCEM-UA优化算法所得理论频率曲线与实测数据两端值的拟合效果更好。【结论】与传统适线法相比,基于SCEM-UA优化算法的优化适线法能够降低理论水文频率分析的误差,提高理论频率曲线与实测数据的拟合精度。     

基于局部阈值的植物叶片图像分割算法研究

提供了采用数字图像处理方法快速分割含边框植物叶片的方法,分别采用局部阈值分割和最佳阈值分割获取二值图像,得到局部阈值分割效果较好的结论,最终得到了比较清晰的边框图像和叶片二值图像,为后续图像处理打下良好基础。     

灌区节水灌溉决策支持系统研制

为促进灌区管理水平和工作效率的提高,采用Borland Delphi高级编程语言,开发了具有水分生产函数计算、作物需水量计算、水资源优化分配、节水灌溉决策等多种功能的灌区节水灌溉决策支持系统,并以河北大名县某灌区为例进行了应用分析。结果表明:采用该系统可制定出科学合理的灌溉决策,指导农民进行合理灌溉,使有限的水资源发挥最大的灌溉效益。     

具阶段结构两种群捕食模型的渐近行为及最优捕获

对一类具有阶段结构的两种群捕食模型进行了研究,讨论了该系统正平衡点的存在性与唯一性,得到了该系统唯一正平衡点全局渐近稳定的条件,由最优控制理论获得了最优捕获策略.     

Slip Line Field of Plane Strain Problem Obeying the GeneralizedHoek Brown Failure Criterion

According to the characteristics of plane strain problem of elastic and plastic mechanics, the bi parametric expressions were derived for stress components satisfying the generalized Hoek Brown failure criterion. Being substituted into the static equilibrium partial differential equations, a group of first order hyperbolic pseudo linear differential equation partial differential equations was obtained. Utilizing the determinant method and proper variable transformation, the characteristic direction and the differential relation equation for the stress partial differential equations were acquired. The characteristic direction indicted that in plastic zone obliquely intersecting conjugate shear slip surfaces formed two families of non orthogonal slip lines, in which conjugate angle varied with the limit stress state and the material physical properties of Hoek Brown rock mass. Since the principal direction of the maximum principal stress was circumferential in perfectly elasto plastic surrounding rock of the plastic zone around a circular opening suffering the symmetric initial stress field, the angle between the tangential direction of slip line with the principal direction of the maximum principal stress was the function of the minimum principal stress(i.e. the radial stress). Combined with the analytical solution, the polar coordinate differential equation was derived and furthermore, the polar coordinate curve equation for the slip line was obtained.     

A fuzzy fusion approach to gabor transform optimal channels for facial expression recognition

According to its characteristics of multi-direction and multi-scale, Gabor wavelet is divided into 13 channels. Due to different contributions of different channels to the recognition rate, a fuzzy integral fusion approach for facial expression recognition is proposed based on optimal channels. Firstly, three optimal channels are selected according to three proposed principles. And then Gabor features of facial expressional images through those optimal channels are extracted with the dimensions reduction. Finally, each optimal channel is used as a classifier and three classifiers are fused based on multi-classifier combination with fuzzy integral. With the results on JAFFE database, it is found that the recognition rate of the proposed algorithm is 94.41%, which verifies the effectiveness of the proposed algorithm.     

Vehicle stability control system design using optimal allocation of yaw moment

In order to improve vehicle handling stability,a control system using optimal allocation of yaw moment was designed.The first layer is a linear quadratic regulator (LQR) controller,which optimizes a desired yaw moment to work on the vehicle and calculates reference wheel slip for the target wheel.The second layer of the control system is a PID controller which can track the reference wheel slip rate,and then apply braking torque on the target wheel to make the vehicle stable.Simulations are carried out by using an 8-dof nonlinear vehicle model under different conditions.The simulation results indicate that the designed control system can effectively improve vehicle handling stability.     

基于GIS的森林消防水资源空间区域分布优化配置研究

采用GIS空间分析技术,首先在森林火险等级的基础上,将道路网络作为关键要素,以时间作为道路的代价,确定每个消防供水设施点的服务范围,分析防火水资源空间分布现状。然后应用DEM模型,对不能满足森林防火需求的区域,提出改进方案,采用面积占优网格模型,以最大覆盖高火险森林区域面积为目标,建立评价模型,对广州市白云区森林防火水资源分布进行整体优化。实践表明在投入很小,仅新增几个供水设施点的情况下就能极大满足森林防火需求,提高森林防火水资源合理配置水平,对预防森林火灾及森林火灾的有效扑救具有重要的意义。     

地黄不同品种物质生产与养分吸收特性的研究

摘要：以8个地黄品种（2个栽培种、3个变异种,3个野生种）为研究对象,通过分析不同生育阶段地黄干物质生产和养分吸收特征,以期为合理施肥,制定地黄高产优质栽培技术提供依据。结果表明：不同地黄品种物质生长和养分吸收表现出较大差异,集中表现在栽培种显著高于野生种。在人工栽培过程中,形成100公斤地黄经济产量的氮磷钾养分需求量平均为2.10 kg (1.6~2.50),0.48 kg (0.29~0.60) 和1.8 kg (1.41~2.16)。氮钾肥吸收高峰期出现在中期,生育后期养分吸收增加较中期有所减少,而磷素吸收高峰则一直延续到收获。依据上述结果,我们认为,必须降低地黄人工栽培过程中基施氮肥的比例,大量的氮肥应施在地黄快速生长期,适当的增加中后期磷钾,特别是钾肥使用有助于增加地黄的生长,提高地黄经济产量。     

中国中低产田时空分布特征及增产潜力分析

改造中低产田,挖掘现有耕地的生产潜力是实现耕地总量动态平衡,提高我国粮食综合生产能力,保障未来我国粮食安全的主要途径之一。本文利用全国农业分县数据及全国第二次土壤普查数据,对我国中低产类型、时空分布特点以及增产潜力进行了研究。结果表明：1985-2008年,我国耕地质量逐步提高,低产田比例由50.01%下降到28.61%,中产田的比例由24.86%提高到37.91%、高产田的比例由25.13%增加到33.48%,中低产田主要分布在东北区、华北区、以及长江中下游区;中低产田的主要类型为瘠薄型、干旱缺水型、坡耕地型、渍涝水田型、渍涝旱地型、盐碱型、风沙型等。分析了我国中低产田改造的增产潜力,在此基础上提出了中低产田改造的技术对策、发展方向和政策建议。