呋喃自硬树脂砂应用"A+B"固化剂

呋喃自硬树脂砂的固化,在生产过程中通常采用一种固化剂,总酸度不变,用改变加入量调整砂块固化程度来达到起模.而A B是两种不同总酸度的固化剂,通过改变两种固化剂的各自用量,达到总量不变,而总酸度改变,使砂块的固化和强度得到稳定.     

航天器非线性神经元控制方法研究

针对航天器控制问题,提出了一种非线性动态逆与状态反馈控制相结合的神经元控制系统设计方案,并成功的将其应用于登月舱软着陆过程的控制问题.该方案包含两部分:①应用神经元网络通过学习建立被控系统的非线性动态逆模型,实现被控非线性系统的线性化;②在线性化模型的基础上构造系统的神经元最优状态反馈控制器.本文给出的仿真结果显示出神经计算学在航天器控制问题中所具有的潜在能力.     

智能计算机辅助汉语教学系统的汉语知识表达

本文对智能计算机辅助汉语教学系统中汉语知识的表达进行了研究，提出了汉语知识分层联想网络表达方法。该方法具有网络模型和特征比较模型两种知识表达方法的特点，较好地反映了汉语教学活动中教师的心理过程，使智能计算机辅助汉语教学系统能有效地进行汉语教学，体现出较强的智能特征。     

自学习模糊控制系统的研究与实现

本文通过简化模糊控制算法中的模糊关系，建立了一种运算量少，易于实现实时控制的自学习模糊控制算法，数字仿真结果及其在单片微机温度控制系统中的实时运行情况表明，该算法控制效果良好，具有实际应用价值。     

Experimental evaluation of two iterative reconstruction methods for induced current electrical impedance tomography

The Newton-Raphson (N-R) with two different regularization methods: the Levenberg-Marquardt (N-R-LM) and the Hachtel's Augmented Matrix (N-R-HAM), were used to reconstruct images of conductivity changes in a cylindrical medium by Induced Current Electrical Impedance Tomography (ic-EIT). Experimental data were obtained from an 8-cm high, 19.2-cm diameter tank with 16 electrodes on the boundary surface and surrounded by eight 50-cm diameter coils. The coils were angularly displaced by 45 degrees and offset 12.4 cm from the center of the tank. They were driven by a 150-mA (peak) 20-kHz sine wave. Potential differences between adjacent electrodes were measured with phase-sensitive demodulators. The scalar potential field in the electrode plane of the conducting medium, resulting from eddy currents generated by each coil, was computed by the Finite Element Method. Image reconstruction by the N-R-HAM method was found to provide higher resolution and better noise immunity than the N-R-LM method. Two 2.2-cm diameter nonconducting rods located 3.9 cm from the center of the tank, 180 degrees from each other, were clearly resolved. Spatial resolution is estimated at 15% of the tank diameter and is comparable to the resolution obtained by conventional EIT using the Sheffield protocol. Higher resolution could be achieved with more coils and/or electrodes. A 16-coil system should present no construction problems. However, voltages induced by stray magnetic flux through the electrode leads and measurement circuits are significant and may limit the ability of ic-EIT to perform static imaging of conductivity distributions.     

设计模糊控制器的一种方法

本文提出一种设计模糊控制器（ＦＣ）的方法,该方法将于Ｅｉ,ＥＣｊ,Ｕｋ分别定义为各自论域上的模糊划分,采用代数乘和代数加运算,量化等级可以根据需要而定,简化算法可以实现实时在线计算,内存只存储控制规则和隶属度函数,计算复杂度与量化等级无关;设计的模糊控制器具有良好的动态和稳态性能。     

First-principles study of the growth and diffusion of B and N atoms on the sapphire surface with h-BN as the buffer layer

Currently,the preparation of large-size and high-quality hexagonal boron nitride is still an urgent problem.In this study,we investigated the growth and diffusion of boron and nitrogen atoms on the sapphire/h-BN buffer layer by first-prin-ciples calculations based on density functional theory.The surface of the single buffer layer provides several metastable adsorp-tion sites for free B and N atoms due to exothermic reaction.The adsorption sites at the ideal growth point for B atoms have the lowest adsorption energy,but the N atoms are easily trapped by the N atoms on the surface to form N-N bonds.With the in-creasing buffer layers,the adsorption process of free atoms on the surface changes from exothermic to endothermic.The diffu-sion rate of B atoms is much higher than that of the N atoms thus the B atoms play a major role in the formation of B-N bonds.The introduction of buffer layers can effectively shield the negative effect of sapphire on the formation of B-N bonds.This makes the crystal growth on the buffer layer tends to two-dimensional growth,beneficial to the uniform distribution of B and N atoms.These findings provide an effective reference for the h-BN growth.     

变电站高压断路器分合闸装置故障分析及性能优化设计

针对近些年断路器故障频发现象,介绍了断路器操作机构故障现状及故障类型;详细分析了断路器分合闸装置工作机理;并通过某变电站断路器分合闸线圈烧毁的原因剖析,提出了两种解决方案,根据电力系统实际,对两种方案进行比较和优化设计,最终选取加装一个并联的电压监视继电器,来进行分闸回路的通电监视的策略,切实保障了变电站等电力系统稳定、高效、安全运行。     

基于向量地震动强度指标的拱坝地震易损性分析

将地震动顺河向分量的一、二阶谱加速度以及地震动横河向、顺河向分量的一阶谱加速度分别作为反映地震动强度的向量指标,建立了以拱冠位移、横缝开度和损伤体积比为性能指标的拱坝地震易损性曲面,以预测拱坝在不同强度水平的地震作用下达到各级破损的概率。以白鹤滩拱坝为研究对象,考虑地震动以及材料的不确定性对拱坝进行增量动力分析,将分析结果取对数后进行二元线性回归,得到概率地震需求模型,然后建立了不同性能指标的拱坝地震易损性曲面,并对基于向量地震动强度指标和基于标量地震动强度指标进行拱坝地震易损性分析的效率进行了比较。研究结果表明:基于向量IM的易损性分析能够显著降低拱坝地震需求预测的离散性,同时基于向量IM比标量IM更加高效,采用基于向量IM的地震易损性曲面对拱坝进行易损性分析能更加准确地评估拱坝的抗震性能。