Leucaena (Leucaena leucocephala (Lam) de Wit) prunings as nitrogen source for maize (Zea mays L.)

The effectiveness ofLeucaena leucocephala (Lam.) de Wit, prunings as N source for maize (Zea mays L.) was evaluated in field and pot trials at Ibadan, southern Nigeria. An N deficient, sandy Apomu soil (Psammentic Usthorthent) was used. The prunings significantly increased N uptake of seedlings and N percentage in ear leaves of maize. High maize gain yield was obtained with application of 10 tons fresh prunings or a combination of 5 tons fresh prunings and N at 50 kg ha^–1. The prunings as N source, appeared to be more effective when incorporated in the soil than when applied as mulch. In the pot trial, prunings applied two weeks before planting was more effective than when applied at time of planting maize. Under screen house conditions, the apparent N recovery from prunings with early incorporation about equals that of fertilizer N.     

Use ofLeucaena leucocephala (Lam. de Wit) leaves as a nitrogen source for crop production

Field and pot trials were conducted to determine optimum management practices for usingLeucaena leucocephala (Lam. de Wit) leaves as a N source for crop production. Field trials with maize showed no benefit from split application of leucaena leaves or from application of fresh as opposed to dried material. Field trials also failed to show any difference between incorporation as opposed to surface application of leucaena leaves. This may be attributed to the low nitrogen response observed. Pot trials however, showed that soil incorporation of leucaena leaves was more effective than surface application in increasing plant dry weight.Leucaena leaves were not as effective as inorganic N in increasing maize grain yield (field trials) or dry matter production (pot trial). Unlike inorganic N, leucaena leaves had a significant residual effect on the succeeding maize crop. In decomposition studies, buried leucaena leaves decomposed more quickly than surface-applied leaves, and fresh leaves decomposed more rapidly than dried leaves.     

结构健康监测中传感器优化设置方法研究

首先探讨了3种基于数据信息最大化准则的传统传感器优化布置方法,即有效独立法、有效独立驱动点-残差法及运动能法.其中前2种基于Fisher信息阵最大化,而第3种基于运动能最大化.然后运用结构振动模态和三样条插值模态之间的均方差最小和抗噪性能最好,这两种比较准则来确定最优的传感器设置方法.数值分析表明:这3种传感器优化布置法都是有效的,而有效独立-驱动点残差法的效果最好.     

基于蚂蚁算法的电子元器件位置优化

首先介绍了基本蚂蚁算法原理和改进的蚂蚁算法，即最大-最小蚂蚁算法，根据传热学原理用微元体热平衡法建立了电子系统热分析求解温度场的数学模型，并采用高斯-赛德尔迭代法求解热平衡方程组，通过仿真实验证明用蚂蚁算法来优化电子元件的布局能够显著降低最大温度值，并提高了系统的可靠性。     

A study of the optimal measurement placement for parameter identification of orthotropic composites by the boundary element method

This paper concentrates on the design of the optimal measurement placement for the parameter identification of two-dimensional orthotropic composites, which is modeled by the boundary element. From the analysis of the well-posedness of the parameter identification processes using the Levenberg–Marquardt method, a performance indicator and an estimation of the maximum bias of identified parameters are deduced. Based on these results, a method for selecting the optimal measurement placement is proposed. The validity of this method is illustrated by some numerical examples. These examples reveal that the measurement placement has significant influence on identification results. Furthermore, an iterative process of selecting measurement placement is suggested for practical implementation.     

基于极点配置的电动舵机控制器设计

介绍了一种极点配置控制器的设计原理和方法,建立了电动舵机位置伺服系统的数学模型,运用基于传递函数的极点配置方法设计电动舵机位置伺服系统控制器,并对系统进行仿真,在实际舵机系统也进行实验.仿真及实验结果表明：该控制系统有较好的动态跟踪性能.     

永磁同步平面电动机三自由度运动控制器

建立了永磁同步平面电动机动子的3自由度动力学模型,并在偏摆角位移较小的假设基础上,对动力学模型进行了简化,进而拟定了通过同时调节4个电磁推力以产生所需偏摆限位转矩的力控制策略。此外,基于状态空间极点配置法,分别设计了与3个自由度对应的位置伺服控制算法,并且对所建立的控制系统进行了数值仿真,仿真结果表明所采用的控制策略和控制算法使控制系统达到了预期的动、静态指标。     

LMI Approach to Robust H∞/H2 Controller Design with Regional Poles Constraint of a Pump-Motor System

Whenfacing withthe practical servosystemcon-trol problem,the control systemis often required tomeet many performance indexes which include ti medomain,frequency domainand H∞/H2.Theseindex-es have explicit purpose and appliedsituation.For ex-ample,the H∞normbetween disturbance and outputrepresents the capability of noise-i mmune,the smallerthe H∞normis,the more excellent stiffness the sys-temhas.And the square of H2norm between inputand output is equal to the energy of the systempulserespo…     

PMU配置不完全可观测系统状态计算

对配置PMU系统,从网络节点方程解算理论入手,提出了系统可观测性判定算法,将系统节点分为动态可观测节点和不可观测节点。如何求得不可观测节点的电压相量,一种方法是视可观测节点为Vθ节点的潮流方法;另一种方法是将不可观测节点功率注入等效为等值阻抗(导纳)形式,用可观测节点电压的线性组合形式来表示不可观测节点电压。该文分析了两种方法各自的特点,算例分析验证了方法的有效性。     

配电系统测点布置方法研究

提出了一种配电系统测点布置的新方法。该算法在基于支路电流的状态估计方法的基础上,定义了测量量对测量误差总方差的“灵敏度因子”,通过比较其大小,得到了配电网测点布置的方案,即能以较少的测量点获得较高的估计精度,且计算量少。文中利用IEEE33节点的配电系统进行仿真试验,证明了算法的正确性和合理性。从而,为应用于实际规模的网络提供了一个新途径。