航海船舶多维振动主动控制研究

采用基于并联机构和电磁作动器的多维振动主动控制装置,实现了对船舶航行中面临的多维低频振动衰减。对振动控制装置进行了结 构设计、系统控制模型分析和控制算法研究,并制作样机进行了实验研究。样机试验结果表明,该多维减振装置能够实现船舶多维低频振动主 动控制。     

语言简洁性策略在科技汉英翻译中的应用

科技汉英翻译是一个将科技汉语转换为科技英语的过程。科技英语基本特点之一就是简洁性,在进行科技汉英翻译时,可以充分利用结构手段在英语译文中体现简洁性要求。     

Differential Responses of Wheat Inhibitor-like Genes to Hessian Fly, Mayetiola destructor, Attacks During Compatible and Incompatible Interactions

Four groups of inhibitor-like genes that encode proteins with diverse structures were identified from wheat. The majority of these genes were upregulated by avirulent Hessian fly, Mayetiola destructor (Diptera: Cecidomyiidae), larvae during incompatible interactions, and were downregulated by virulent larvae during compatible interactions. The upregulation during incompatible interactions and downregulation during compatible interactions resulted in four- to 30-fold differences between the expression levels in resistant plants and those in susceptible plants. The increased expression of inhibitor-like genes during incompatible interactions suggested that these genes are part of defense mechanisms in wheat against Hessian fly attacks, whereas the downregulation during compatible interactions suggested that virulent larvae can suppress plant defenses. Both the upregulation of the inhibitor-like genes during incompatible interactions by avirulent larvae and the downregulation during compatible interactions by virulent larvae were through mechanisms that were independent of the wound response pathway.     

Phenotypic and genotypic variability of F2 plants derived from Jatropha curcas × integerrima hybrid

Phenotypic and genotypic variability were evaluated in a population of 227 F₂ plants derived from an interspecific cross between Jatropha curcas (cv. “Chai Nat”) and Jatropha integerrima (local dwarf ornamental type) from Thailand. The objective of this study was to assess the range of variability for 13 phenotypic characters and 16 EST-SSR markers observed in the population. A high variation was found in morphological characters showing many superior genotypes over the J. curcas parent. The results of molecular parameters also suggested a high level of genetic variability in the current population with 100% of polymorphic loci (PPL) for all 16 SSR primers used. The mean numbers of observed alleles (Na) and effective alleles (Ne) were 2.13 and 1.81, respectively. The polymorphic information index (PIC) ranged from 0.17 to 0.55 with an average of 0.34. The average values of Nei's genetic diversity (He), observed heterozygosity (Ho), and Shannon's information index (I) were 0.43, 0.47, and 0.64, respectively. Jaccard's similarity coefficient ranged from 0.51 to 0.96 with a continuous distribution. The UPGMA-based dendrogram could not classify the F₂ plants into clusters, but separated them into three sub-groups and seven distinct plants at 61% similarity. The information generated from the current research will be of great benefit to jatropha breeding program; providing a new gene source to the currently low variation in J. curcas.     

基于多维度排列熵与支持向量机的轴承早期故障诊断方法

针对许多现有方法无法有效诊断滚动轴承早期故障的问题,引入排列熵的方法对轴承振动信号进行早期故障分析。通过研究嵌入维数和延迟时间对信号排列熵的影响,提出多维度排列熵的特征提取方法。利用多维度排列熵方法所提取的特征,建立了基于支持向量机的轴承早期故障智能诊断模型。对轴承不同类型、不同程度的故障数据进行分析,证明了多维度排列熵方法可以有效提取轴承不同状态的特征信息,与支持向量机结合的智能诊断模型可以精确地诊断轴承不同类型的早期故障,具有很强的通用性;该模型在贫样本的情况下,依然具有很高的诊断精度,适用于滚动轴承早期故障状态的在线监测。     

基于多嵌入维数的时用水量LSSVM组合预测

为解决供水系统调度所需混沌时用水量高精度预测等问题,将最小二乘支持向量机(LSSVM)组合预测模型应用到城市时用水量预测中。在分析不同嵌入维数和预测方法对模型预测精度影响程度的基础上,提出了基于多嵌入维数的LSSVM组合预测模型。采用互信息法和G-P方法求取多个嵌入维数,并建立了不同相空间模型,通过LSSVM算法对上述多个预测模型进行了组合预测,既综合了各不同嵌入维数各预测方法下的信息,又对单一模型下的预测偏差进行了融合,以有效地提高预测精度;最后在某地进行了时用水量序列的仿真实验。研究结果表明,该模型预测精度平均误差小于2%,明显优于各单一模型的预测结果,证实了该组合模型的有效性和实用性。     

奇数阶累积量的计算优化及其应用

为了用奇数阶累积量提取非线性振动系统的高次频率耦合特征,定义了四次频率耦合、二三对频率耦合等高次耦合新概念,分析了奇数阶累积量特征,研究了奇数阶累积量计算方法与计算量间的关系,提出了奇数阶累积量计算优化算法,该算法将奇数阶累积量的直接估计变为递推估计,将奇数阶累积量的多维运算转化为一维运算,大幅度减小了计算量,在工程上具有可实现性。用由计算优化算法估计的奇数阶累积量构造的自适应谱线增强器,能有效地从高斯噪声环境中恢复或提取四次频率耦合特征、二三对频率耦合特征等高次耦合特征。理论分析与仿真结果验证了算法的有效性。     

CBR中的检索模型研究

事例检索模型直接影响基于事例推理(Case-BasedReasoning,CBR)的结果。该文提出了一种将多概念学习的决策树算法、多维加权贴近度法与模糊综合评判法相结合的事例检索模型,并根据事例状态的属性设计了几种隶属度函数。分析了此模型的优缺点,指出了今后的改进方向。     

多维链表的递归实现算法研究

通过对多维链表的研究,提出了较完整的多维链表的数学模型,并给出它的递归实现算法。