共查询到20条相似文献，搜索用时 140 毫秒
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本文从流固耦合的基本原理出发,以ANSYS软件为工具,对流体精密抛光二维高频振动中的振动槽体在双超声振动和机械一超声振动两种不同的工况、多组不同振动频率条件下的状态进行了流固耦合分析。整个分析过程模拟了抛光过程中流体在二维振动耦合下的振动场分布,获得振动场中流体的。运动轨迹,并得出了流体在振动场中的运动规律。 相似文献
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顾熙棠 《宁波大学学报(教育科学版)》1988,(1)
本文对工作机械的相对振动进行了理论和实验研究。分析了相对振动的激励和合成原理,提出了工件和工具同相振动和异相振动、同相域以及相对振动放大因子等概念。在此基础上指出了减小相对振动的途径,以作为设计和改造工作机械的参考。 相似文献
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在机械加工中产生的振动有强迫振动和自激振动,振动会恶化加工表面质量,损坏切削刀具,降低生产率。本文分析了车削加工中振动的主要类型及产生的原因,并从刀具、夹具、切削工艺等方面提出了减小或消除振动的措施。 相似文献
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主要研究了一维单原子链中间隙式杂质引起的品格振动图像,分析了杂质质量和恢复力系数对振动模的影响.通过数值求解晶格振动振动方程组,得到周期性振动频率和局域振动模频率,并在此基础上讨论(g,ε)对局域模频率的影响. 相似文献
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主要研究了一维单原子链中间隙式杂质引起的晶格振动图像,分析了杂质质量和恢复力系数对振动模的影响。通过数值求解晶格振动振动方程组,得到周期性振动频率和局域振动模频率,并在此基础上讨论（g,ε）对局域模频率的影响。 相似文献
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从理论上分析了柱形弹簧振动系统的振动情况，并给出了柱形、锥形弹簧振动系统振动周期相对于弹簧质量、振动物体质量的实验结果。 相似文献
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《实验室研究与探索》2013,(11)
为了进一步深入研究变压器的振动特性及其影响因素,提高变压器绕组变形振动检测技术的准确性,通过定制2台10 kV电力变压器,设计和搭建了变压器振动特性测试平台。基于该平台,借助于变压器空载试验、短路试验和负载试验,得到了变压器箱壁振动信号特性及其与变压器工作电压、绕组电流和功率因数之间的关系曲线。结果表明,变压器绕组振动与电流的平方线性相关,铁芯振动与电压的平方线性相关,变压器箱壁振动为绕组振动与铁芯振动的非线性叠加。研究结果可为基于振动分析法的变压器绕组变形监测技术及其应用提供依据。 相似文献
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利用弯曲振动法测取了纤维板的声振动参数并进行了分析比较,结果表明:密度大的纤维板其振动加速度较大,振动能量损耗较低,声反射能力较强,但声辐射能力较弱;厚度小的纤维板其振动加速度较大,声反射及声辐射能力均较强,但振动能量损耗较高. 相似文献
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设计了光电传感器实现绝对式振动测量,推导了测试系统的振动方程,方程为常系数二阶微分方程。通过激振器产生20Hz~10 kHz连续变化的振动信号,由光电传感器得到振动波形,Lab VIEW频域分析得到被测体的振动频率分布等。结果表明,光电振动测试系统的输出频率与激振器相同。该振动测试方法具有非接触、远距离、抗电磁干扰、测量精度高、频率响应宽、成本低等优点。 相似文献
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《International Journal of Educational Research》2001,35(4):373-389
This chapter presents and discusses the results of the study. The results are presented in three sections: results of the correlational analysis, results of the regression analysis, and results of the path analysis. In general the results suggest that family background is indirectly linked to GPA by virtue of its direct effect on study behaviors, verbal ability, and nonverbal ability. Similarly, the link between study behaviors and GPA is mediated through verbal ability and nonverbal ability. Family background and study behaviours consistently predicted nonverbal ability, verbal ability, and GPA, even after the effects of the other cognitive variables had been removed. 相似文献
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成绩分析是每次考试之后教师的首要工作,利用Office内置的VBA,实现了成绩分析,并且利用统计后的数据自动生成PowerPoint演示文稿,极大地提高了成绩分析的工作效率． 相似文献
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丁念金 《集美大学学报(教育科学版》2002,3(1):22-25
与其他学习方式一样 ,研究性学习也必须追求一定的结果 ,只是研究性学习所应该追求的结果与其他学习方式所追求的结果不同。研究性学习的结果包括知识、科学探究能力、科学精神、独立性与合作性、社会责任感等基本方面 ,具有综合性、渐效性和非预定性等显著特点 ,这些特点给我们以重要的启示 相似文献
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本文通过对糯玉米评价体系进行量化,以形成量化评定的结果,从产量和品质两方面,依次与原始评定结果及排序进行比较.最后得出:量化指标评定体系是目前较为科学、合理的方法. 相似文献
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Large‐scale assessment results for schools, school boards/districts, and entire provinces or states are commonly reported as the percentage of students achieving a standard—‐that is, the percentage of students scoring above the cut score that defines the standard on the assessment scale. Recent research has shown that this method of reporting is sensitive to small changes in the cut score, especially when comparing results across years or between groups. This study builds on that work, investigating the effects of reporting group size on the stability of results. In Part 1 of this study, Grade 6 students’ results on Ontario's 2008 and 2009 Junior Assessments of Reading, Writing and Mathematics were compared, by school, for different sizes of schools. In Part 2, samples of students’ results on the 2009 assessment were randomly drawn and compared, for 10 group sizes, to estimate the variability in results due to sampling error. The results showed that the percentage of students above a cut score (PAC) was unstable for small schools and small randomly drawn groups. 相似文献
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Resonant frequencies of a piezoelectric drum transducer 总被引：1，自引：0，他引：1
This paper presents a piezoelectric-metal structure called a drum transducer. An equation for calculating the resonance frequency of the drum transducer is obtained based on thin plate elastic theory of piezoelectric and metal material combined with the Rayleigh-Ritz method. The finite element method （FEM） was used to predict the excitation frequency of the drum transducer. To verify the theoretical analysis, the input impedance characteristic of the drum transducer was measured using an experimental method. The results obtained from theoretical analysis were in very good agreement with those from the FEM and experimental results. The effect of geometrical changes to the thick-walled steel ring of the drum transducer at the first resonance frequency is also described. The calculated results were found to be in good agreement with the FEM results. The results indicate that the first resonance frequency of the drum decreases with the increasing inner diameter of the thick-walled steel ring. 相似文献