Dietary evaluation of pregnant adolescents during first, second and third trimester

In order to identify risk of inadequate intake of calories and nutrients during pregnancy, 75 pregnant adolescents (14 to 18 years old) apparently healthy, from low socioeconomic level, in their first prenatal control (12 weeks) were studied by two 24 hour recalls and a food frequency questionnaire at each trimester. Nutritional status was assessed by body mass index (pregestation weight/height) and classified according to American Medicine Institute reference. Paired t-test, frequency distribution and ANOVA were used for statistical analysis. Low weight was found in 34.6% of adolescent at the first visit and 5.3% were overweight. Even though, caloric intake was below recommendation, significant increases were observed between first and second trimester for energy, carbohydrates, niacin and zinc (p < 0.001) and for fat, proteins, riboflavin, thiamin, vitamin C, calcium and iron (p < 0.05). From second to third trimester, differences (p < 0.05) were significant only for vitamin A. Between first and third trimester, differences were significant (p < 0.05) for energy, proteins, carbohydrates, niacin, riboflavin, zinc and for thiamin, vitamin A and calcium (p < 0.05). A high proportion of pregnant adolescent did not reach recommendations for energy, folate, calcium and zinc. Food intake pattern did not change significantly among trimesters. Mean total weight gain was 9.2 kg and 0.412 +/- 0.4 g/week. Newborn's mean weight was 3.221 +/- 418 grams. It is concluded that adolescents are at high nutritional risk and deficiency of dietary intake should be followed. Attention should be addressed from the preconceptional period to postpartum in order to improve maternal and fetal conditions.     

情感计算与工程理性*

通过对情感与理性的相容性分析以及情感在集成、适应、动力和交互等方面的功能研究,指出情感是人类解决现实复杂问题的有效机制。在情感功能与工程需求的适配性分析的基础上指出,围绕情感所展开的情感计算在复杂工程问题的求解上潜力巨大,具备有效性和一定的必要性。提出了情感计算在工程领域研究的本源性、相关性和可操作性策略,指出情感计算的工程实现需要对研究的切入点、情感发生机制、情感效应机制、平台选择等关键环节予以关注,并给出了相关建议。     

基于Tsallis熵差的遥感图像边缘检测方法

基于Tsallis熵差和百分位形态变换,提出了一种改进的遥感图像边缘检测方法。该方法通过构造基于百分位形态变换的边缘检测算子和选择不同方向结构元素进行变换来增加图像的边缘信息,并且该方法在百分位形态变换的基础上还改进了百分位变换的评价准则。它利用图像Tsallis熵差来选择边缘检测算子的百位变换值,将选择Tsallis熵差最大的百分位变换作为变换结果。实验结果表明,与传统的基于数学形态学的边缘检测方法相比,该方法可以最大程度上抑制噪声,有效地提高图像的边缘检测效果。     

负载平衡路由：一种新的ACO路由策略*

通过改进ACO算法达到一种能实现通信网络负载平衡的群体智能路由策略。采用的主要方法为：将蚁群划分为若干个子群,不同子群的蚂蚁释放不同类型的信息素。通过不同类型信息素之间的相互制约作用,以及链路负载的测量,提出了三种策略实现负载平衡路由。在模拟网络上进行了不同策略的对比实验,以及与已有的群体智能路由算法的运行测试比较。实验结果表明,本文的路由策略具有较好的效果和一定的优势。     

基于TreeMiner算法的XML文档结构相似度量方法*

提出了一种基于TreeMiner算法挖掘频繁子树的文档结构相似度量方法,解决了传统的距离编辑法计算代价高而路径匹配法无法处理重复标签的问题。该方法架构了一个新的检索模型—频繁结构向量模型,给出了文档的结构向量表示和权重函数,构造了XML文档结构相似度量计算公式;同时从数据结构和挖掘程序上对TreeMiner 算法进行了改进,使其更适合大文档数据集的结构挖掘。实验结果表明,该方法具有很高的计算精度和准确率。     

基于结构的e mail挖掘算法：EHITS*

在总结和分析Web网络中经典的链接分析算法(HITS算法)的基础上,提出了一种从邮件语料中发现全局权威人物的EHITS算法。首先,详细介绍了该算法中选取种子、扩展种子集和迭代计算的方法,并通过实验与其他方法进行了比较;最后,对该算法在安然邮件语料库上的实验结果进行评价。结果表明,该算法在邮件语料库中发现全局权威人物方面是非常有效的。     

基于自相似背景模型的MANETs流量性能分析*

利用IP数据包长度的经验分布和具有重尾特性的Pareto分布,构造出基于自相似背景模型的MANETs业务流量性能仿真系统。在此仿真系统的基础上,针对不同的参数进行了一系列的仿真实验。仿真结果表明,背景流量的自相似程度和业务流量的类型对于MANETs性能有很大影响。     

无线传感器网络中的数据融合及其能效评估*

首先介绍当前无线传感器网络中具有代表性的数据融合算法;然后基于树型网络拓扑结构,结合节点休眠调度机制,建立传感器节点的能量模型;最后提出从能量的角度评价不同数据融合算法性能的方法,并通过模拟对典型数据融合算法进行分析.     

借助外力助推的双足机器人越障及避障方法研究

由于仿人机器人在跨越大尺度障碍时需要重心大幅度地偏移,从而导致机器人容易摔倒或是跨越的距离有限,而通过引入外力的方法能有效地改善机器人的跨越性能.本文主要研究双足机器人在额外外力的辅助下,无碰撞地跨越大尺度障碍物的问题.首先,通过树形数据结构、相对轴矢量和相对位置矢量,建立了双足机器人的仿真模型.然后,通过规划多次曲线跨越轨迹、引入整个跨越过程中的局部避障非线性约束和其他跨越约束的方法,建立起双足机器人越障及避障的多变量非线性优化模型.最终,求解出了平面6自由度的冗余机器人越障及避障的2维步态,通过仿真验证了其能够跨过高度为其腿长43%的障碍物.原理样机跨越15 cm高,为其腿长32%的障碍物,证明了本文所提越障及避障方法的有效性.     

Features of the motion of gel particles in a three-phase bubble column under foaming and non-foaming conditions

Features of the motion of gel particles in a three-phase bubble column with non-foaming and foaming gas–liquid systems,determined by using experiments of radioactive particle tracking(RPT),have been compared.The tracer used is a gel particle which resembles typical immobilized biocatalyst.The tracer trajectory is analyzed to extract relevant information for design purposes.The solid velocity field,turbulence parameters,dispersion coefficients,mixing times and flow transitions are determined and compared.The presence of foam significantly affects many quantified parameters,especially within the heterogeneous flow regime.The hydrodynamic stresses are reduced in the presence of foam,especially close to the disengagement.The dispersion coefficients also decrease,and the solid mixing time is only slightly affected by the presence of foam.Gas holdup,inferred both from RPT experiments and from gamma ray scanning,is higher for foaming systems and leads to a shift in the transition gas velocity towards higher values.