中压混合型模块化多电平变换器的载波移相调制策略

由于半桥子模块与全桥子模块的载波移相调制策略不同,两者混合而成的模块化多电平变换器(modular multilevel converter, MMC)不能直接沿用原来的调制策略;在船舶中压直流电力系统中,由于变换器模块数较少,交流输出电压的波形质量相对较差。基于上述原因,通过载波相位角的合理配置,提出一种改进型载波移相调制策略。该策略不仅能够增加交流输出电压的电平数,而且不局限于某种特定的拓扑结构。通过仿真验证其有效性和通用性,验证结果显示它是一种适用于中压混合型MMC的通用调制策略。     

Sex differences and sex bias on the Boehm test of basic concepts: Do they exist?

Form A of the Boehm Test of Basic Concepts (BTBC) was administered to 180 kindergartners—90 boys and 90 girls. Neither their mean scores nor their standard deviations differed significantly, and the distributions of scores for the two groups were virtually identical. Moreover, the application of three internal criteria for bias yielded totally negative results; thus, there was no evidence of either sex differences or sex bias in the data.     

A simple ratio adjustment for baseline recording in natural settings

The usefulness of a baseline record is often compromised by extraneous events in the natural environment that artificially intervene to prevent the performance of a specific target behavior. To attenuate this problem, a simple ratio adjustment procedure was suggested that compares the observed response frequency with a maximum possible frequency for each observation period. This ratio is then transformed into a response percentage with a more general predictive value for the behavior modification practitioner.     

Wishes of fourth-through seventh-grade gifted students

Three wishes and primary wishes of fourth- through seventh-grade gifted students participating in a residential program for the gifted were collected and categorized. The results indicated that males wished for material things more often than did females. With the exception of fourth graders, subjects made altruistic wishes more frequently than any other wish.     

A management program for elective mutism

Behavior modification procedures are described for establishing compliant behavior in elective mutes. The results are discussed for three children to whom the procedure was applied. The length of the training period was two weeks for the first child, twelve days for the second, and six weeks for the third. Two of the three subjects generalized responsive and spontaneous language from the experimental to everyday settings.