共查询到20条相似文献，搜索用时 78 毫秒
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本文建立了分流器的二维有限元模型,分析了分流器电阻以及电感随频率变化的关系。计算结果表明：在高频条件下,集肤效应和邻近效应是增大交流电阻和减小电感的主要原因。 相似文献
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高Q值的片上集成电感是单片集成射频电路、微波电路中不可缺少的重要元件.并联形式的集成电感具有较高的品质因数,但是其自谐振频率较低,使其应用范围受到限制.该文从衬底损耗,金属损耗及邻近效应出发,首次提出了一种提高并联集成电感性能的方法.合理的设计多个不同圈数、层数的电感并将其并联,用ASITIC软件近似仿真发现该型并联集成电感能够在较高频段获得较高Q值. 相似文献
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《东南大学学报》2021,(1)
基于硅转接板工艺实现了超宽带混频微系统组件的三维异构集成,该混频组件由混频多功能芯片和倍频多功能芯片级联而成.基于晶圆级金-金键合工艺实现了四层高阻硅基板堆叠封装.每一层均采用硅通孔(TSV)技术,从而实现信号之间的互连.单片集成微波芯片(MMIC)嵌入在硅腔内,硅基滤波器集成在高阻硅衬底上.硅基转接板上的互连线、腔体以及滤波器采用AutoCAD进行设计,并采用HFSS进行三维电磁场仿真.根据测试结果,混频多功能芯片的射频频率为40～44 GHz,中频频率可覆盖Ku频段,尺寸为10 mm×11 mm×1 mm.倍频多功能芯片工作在16～20 GHz频段,对基波信号的抑制优于50 dB,对二次谐波信号的抑制优于40 dB,尺寸为8 mm×8 mm×1 mm.级联后完全组装的混频组件可实现优于-50 dBc的杂散抑制比和优于15 dB的增益. 相似文献
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张金桥 《暨南大学华文学院学报》2008,(1):22-29
采用词汇判断任务考察了留学生汉语单字词识别中的笔画数效应、词频效应和词素频率效应。包括2个实验,实验1探讨了留学生汉语单字词识别的笔画数效应和词频效应及其相互关系,结果发现存在笔画数效应及词频效应,但其交互作用不显著。实验2探讨了留学生汉语单字词识别的词频效应和词素频率效应及其相互关系,结果表明存在词频效应和词素频率效应,两者间存在交互作用,具体表现为,词频高时词素频率差异不显著,词频低时词素频率差异显著。本研究结果初步表明,笔画可能是留学生汉语词汇学习中的一个加工单元,笔画与词频分别作用于汉语单字词认知加工的不同阶段;在留学生汉语单字词的识别过程中,词频和词素频率同时作用于同一个认知加工阶段,词频具有优势效应,词素频率具有代偿作用。 相似文献
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高Q值的片上集成电感是单片集成射频电路、微波电路中不可缺少的重要元件。衬底损耗、金属损耗及电感螺旋线之间磁通量的相互抵消是限制集成电感品质的主要因素。首次提出了一种利用常规硅工艺实现的新型立体集成电感设计,先在介质层上刻蚀出一个锥形柱面,然后在凹面上镀金属层,利用平面螺旋电感的制造方法,就可制造出立体电感;分析了该集成电感在金属损耗及电感螺旋线之间磁通量的相互抵消等多方面的优势;提出了该型集成电感的两种仿真模型;利用ASITIC软件近似仿真发现该型集成电感能获得较高Q值。 相似文献
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多普勒效应是当波源或者观察者相对于介质运动时,观察者接收的频率发生了变化的现象.要理解多普勒效应,必须先知道波源的频率与观察者接收频率的区别,这是学习多普勒效应的关键:下面谈谈多普勒效应的数学分析. 相似文献
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根据多普勒效应基本原理,利用超声波作为信号源制作了多普勒效应演示仪.利用40 kHz超声波作为信号源,具有频率高、方向性好、发射功率高、不易受干扰等优点,能够在有限的教室空间里实现多普勒效应演示.理论证明,速度为340 m/s的超声波,当物体的运动速度在1～2 m/s变化时,差频的变化范围约为120 ～240 Hz,人耳就能很容易感受到多普勒效应.同时,该仪器还具有制作简单、易携带的优点,并自带测距、测速等附加功能. 相似文献
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叶丽娜 《甘肃广播电视大学学报》2012,22(3):50-52
声波总在一定的介质中传播。如果声波的波源与观察者都相对于介质是静止的,那么观察者接收到的波的频率和波源发出的频率是相同的;但是,若声波的波源和观察者都运动时,也会发生观察者所接收到的波的频率和波源发出的频率不一致的现象,这种现象叫做多普勒效应。多普勒效应在科学研究、空间技术、交通管理、医疗诊断等各方面有着广泛的应用。 相似文献
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Maarten Penninckx Jan Vanhoof Sven De Maeyer Peter Van Petegem 《School Effectiveness & School Improvement》2016,27(3):333-347
There are large differences between schools with regard to how they are affected by a school inspection. This study provides quantitative evidence about the extent to which perceived effects and side effects of an inspection are related to the inspection’s judgement on the school, to features of the inspection, and to school features. This study draws on quantitative data collected from 2,202 teachers in Flemish primary and secondary schools that had recently been inspected. Using path analysis, it investigates the existence and strength of relationships between the perceived effects and side effects of inspection, on the one hand, and the perceived inspection quality, the perceived school’s policy-making capacities, and the inspection judgement, on the other hand. The analysis reveals that most effects and several side effects are predominantly explained by the perceived inspection quality. Emotional side effects during inspection are best predicted by the school’s policy-making capacities. 相似文献
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张云 《河南职业技术师范学院学报(职业教育版)》2008,(3):104-106
隐性课程不同于显性课程,是指学生在课堂内外无意间习得的,采用暗含的、间接的、内隐的方式呈现的教育内容和特定文化序列。隐性课程的认知机制为教学方式和课程设计提供了新的思路,隐性课程也是提高教学效果的一个可利用的重要资源。所以,教师应从教学环境、教学组织、教法的选择与运用、师生互动关系、教学效果测评等方面通过隐性课程来改进教学。 相似文献
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Maarten Penninckx Jan Vanhoof Sven De Maeyer Peter Van Petegem 《Educational studies》2014,40(4):456-472
This study looks into the effects of school inspection in the context of Flemish education. Respondents in five primary case schools were interviewed before inspection, immediately after inspection and four months later (totalling 45 interviews with 15 respondents). Our results indicate that the inspection incites reflection amongst school staff on the quality of their education before the inspection takes place, but the inspection itself does not provide substantial new insights in the schools’ strengths or weaknesses. The inspection judgement strongly affects the response of school towards the inspection. The case schools with a positive inspection report take practically no concrete action for improvement in the four months after inspection, while a more active response is seen in a school with a less favourable inspection report. The article also discusses the impact of some of the particularities of the Flemish education context on the effects of inspection. 相似文献
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A random effects ordered response model of training is estimated to analyze the existence of training tracks and time varying coefficients in training frequency. Two waves of a Dutch panel survey of workers are used covering the period 1992–1996. The amount of training received by workers increased during the period 1994–1996 compared to 1992–1994. Evidence is found for the existence of training tracks in the amount of training courses taken. It is further found that the effects of individual characteristics such as education, age and gender on training should be treated as individual varying coefficients. 相似文献
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王玉玲 《郧阳师范高等专科学校学报》2004,24(6):135-136
应用文教学中存在着机械的套用依例说法的单一教学模式,使应用文教学缺乏生气和活力。应用文教学效果的提高,必须采用多种教学方法、手段,注重教学的生动性、形象性和实践性。 相似文献
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本研究从两个层面( TEM4 和TEM8) 和三个维度( 学科负责人、教师和学生) ,通过问卷调查方式探讨TEM 考试对高校英语专业教学与学习的影响。研究结果显示,学科负责人、教师和学生对考试的关注点 ( 或熟悉程度) 不尽相同;考试成绩在不同程度上给各校提供了评估教学质量和检验学习成果的信息; 然而随着考试影响度的上升,考试成绩也用于院系排名、学位授予、绩效考核、就业与深造等方面;考试未对正常教学秩序或课程造成冲击,但教师和学生受访者内部对考试持不同态度。本研究结果对今后英语专业教学改革具有参考价值。 相似文献
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This paper uses data on roommates from two different selective institutions to investigate the effect of peers on first-year performance, with a specific focus on the underlying mechanism. We compare measures of academic ability across student sub-groups by race, income, and gender, and across institutions. Male, minority, and aided students are affected most strongly by their peers. The size and presence of peer effects are dependent on the ability measure used as well as the setting. Standardized estimates suggest ability measured by high school grades have roughly twice the effect of ability measured by SATs. We also test the use of a standardized measure of first-year performance and find more consistent evidence of peer effects across both schools. Our results provide an explanation for the mixed findings in the literature and suggest that the driving force behind peer effects lies in the transfer of general academic know-how rather than in the teaching of specific knowledge or social proximity. 相似文献
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TONG Shi-liang WANG Yuan-fiang GAO Wen-juan 《重庆大学学报(英文版)》2006,5(2):115-118
As a kind of fast bacteriostatic drugs, macrolides can block both the protein synthesis and the mRNA movement of bacteria via binding to 50S ribosome. Since erythromycin (EM), the 14-membered-ring macrolide was first used clinically as an antibiotic in 19… 相似文献
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利润指标是衡量企业获利能力的一个基本指标,也是度量企业财富增量的一个主要指标.因此利润质量的高低关系到对企业经营评价的正确与否,本文从利润质量研究的必要性入手,着重阐述了利润质量的影响因素,提出了判断利润质量高低的标准. 相似文献