基于遥感影像中电磁特性的地物提取方法

电磁特性数据是电子信息装备内场仿真试验不可或缺的数据资源,为了克服传统电子信息装备仿真试验中的电磁特性数据获取方法的不足,提出了从遥感影像中大批量获取大区域范围的电磁特性数据的新方法.首先依据不同地物的电磁特性规律对某一地域的地物进行了分类,从多尺度分割概念和基于异质性最小的区域合并算法两个方面.深入研究了针对地物分类的面向对象多尺度分割算法,并结合实践对算法进行了应用.由于遥感影像的真实性.保证了电磁特性数据提取的准确性与可靠性,实践证明此研究为大批量获取电磁特性数据提供了一种有效的方法和思路.     

高能激光能量计吸收腔的温度特性

为了提高高能激光能量测量的精确度,减小不准确度,给出了一种吸收腔结构,对基于量热法的吸收腔的内、外壁温度差特性进行了理论研究和实验验证。用一维非线性傅里叶热传导方程分别建立了吸收腔在激光加热过程中和加热结束后的温度分布。利用模拟实验对激光照射吸收腔的过程进行模拟,得到内、外壁温度差的实验数据。利用ANSYS软件,根据激光加热的原理,建立了仿真模型,并用模型对理论分析结果作数值仿真。理论分析结果与实验数据非常接近。在激光照射过程中,虽然吸收腔内、外壁存在渐趋固定的温度差,但当照射结束后,该温差迅速减小,吸收腔到达平衡。     

主成分分析法在火药燃烧规律分析中的应用

本文用多元统计的主成分分析法分析了火药的静态燃烧规律,证实了火药的静态燃烧参量主成分与动态弹道性能p_m、v_0、yv_0的密切相关性,利用主成分与弹道性能建立的回归公式对p_m、v_0、yv_0进行模拟,p_m模拟误差<3%,v_0模拟误差小于1%,yv_0与实测结果有较好的一致性.     

金属型球铁磨球非平衡凝固特性与成分控制

通过分析不同成分球铁磨球零件性能和金相组织,对金属型磨球的非平衡凝固特性进行了较深入的研究.试验结果发现,过共晶球铁凝固时出现非平衡奥氏体;亚共晶球铁出现非平衡渗碳体相和晕圈铁素体;在柱状晶与等轴晶过渡区中存在着夹杂和偏聚物.为改善球铁磨球的显微组织及性能,球铁成分应控制在共晶或稍过共晶范围.     

BAMO-THF复合推进剂能量特性计算与分析

利用最小自由能法研究了以3,3-二叠氮甲基氧丁环(BAMO)与四氢呋喃(THF)共聚醚(PBT)为粘结剂,高氯酸铵(AP)、黑索今(RDX)、铝粉(Al)、二硝酰胺铵(ADN)为固体填料,不同增塑剂条件下推进剂比冲变化规律.理论计算表明: 以2,2-二硝基丙醇缩甲醛与2,2-二硝基丙醇缩乙醛等质量比混合物(A3)、硝化甘油与二乙二醇二硝酸酯等质量比混合物(NG/DEGDN)作增塑剂时,推进剂比冲随RDX含量变化呈抛物线形,固体填料存在最佳添加比; NG/DEGDN增塑体系推进剂比冲高于A3体系.15% ADN取代AP时,由于燃烧产物平均相对分子质量降低,推进剂比冲显著提高.     

煤矿采矿工程中的采矿工艺与技术

阐述了煤矿采矿工程的特点,分析了目前常用的采矿工艺与技术,主要包括充填采矿工艺、空场采矿工艺、煤与瓦斯联合开采技术,并对智能化采矿技术的发展做了简要分析.     

铁矿石的烧结基础特性之新概念

长期以来,人们对烧结用铁矿石的评价主要集中在化学成分、粒度组成、矿物特征等常温性能方面,而对铁矿石在烧结过程中的高温行为和作用知之甚少.根据对这一问题的深入思考和实验室的基础研究,提出了\     

基于神经网络的开关磁阻电动机建模

针对常规的BP算法存在收敛速度慢,容易陷入局部最小值的缺点,提出了一种提高BP网络学习速度的方法,并基于BP神经网络建立了开关磁阻电动机磁特性Ψ(θ,i)模型.神经网络的参数是经过优化选择的,训练的时间和步数都大为减少,程序运行稳定,经过训练、识别、预测三重整定,具有很强的学习泛化能力,大大增强了系统的实时性和鲁棒性.该模型有助于进一步优化能量转换,减小转矩脉动.     

碲镉汞环孔p-n结反常特性分析

在HgCdTe 环孔p-n结器件的研制过程中,经常会出现一些反常现象,如负的开路电压和负的光电压等.现对上述现象进行理论分析,并通过大量实验对上述反常现象进行了验证.     

Predictors of supportive coparenting after relationship dissolution among at-risk parents.

Supportive coparenting after relationship dissolution is associated with increased father involvement which can buffer against the negative effects of parental relationship dissolution. Low-income, at-risk families are much more likely to experience relationship dissolutions; hence, supportive coparenting after dissolution is particularly important in these families. We examined whether relationship (commitment and quality) and child (difficult temperament and gender) characteristics predicted initial levels of, and change in, supportive coparenting after relationship dissolution in the Fragile Families and Child Wellbeing Study (N = 1,603). We used structural equation modeling of latent growth curves to examine four time points collected at the focal child's birth and first, third, and fifth birthdays. Ninety-percent of the mothers had nonmarital births, and about three-quarters had a high school diploma or less education. Overall, supportive coparenting decreased over time. Mothers in more committed relationships prior to the dissolution initially had significantly lower supportive coparenting. But over time, mothers who had been in more committed relationships increased in supportive coparenting. Mothers who had been in higher quality relationships prior to dissolution initially reported more supportive coparenting. At each time point, if a mother was romantically involved with a new partner, she reported significantly lower supportive coparenting compared to mothers who were single. With regard to child characteristics, mothers who reported their child as more difficult had significantly lower initial supportive coparenting. Similar results for fathers are discussed. Overall, the relationship characteristics of parents were important predictors of supportive coparenting both initially and over time. (PsycINFO Database Record (c) 2011 APA, all rights reserved)