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91.
为培养学生的探索和创新能力,自动控制理论实验引入Qube-Servo 2直流电机/倒立摆组件,开展基于PBL (Project-based Learning)的项目式教学革新,支持学生进行创新性和设计性实验。为克服物理设备台套数限制以及传统教学受时空约束的弊端,数字孪生虚拟实验室Quanser Interactive Labs被引入课程,以学生为中心,通过线上线下相结合的教学模式,激发学生的学习兴趣和积极性。此外,思政教育被融入课程教学,以引导学生树立正确的价值观和理想信念。  相似文献   
92.
石墨镶嵌Co纳米晶的形成及其特性   总被引:5,自引:0,他引:5  
用直流碳弧法在阳极石墨棒中加入金属Co产生石墨镶嵌Co纳米晶,研究在复合石墨棒中加入不同的Co含量对石墨镶嵌Co纳米晶的形貌、结构特性及晶粒尺寸分布的影响,探讨石墨镶嵌Co纳米晶的形成原因及碳弧法中氦气压力和Co含量对掺Co阳极石墨棒所产生的碳灰的C60/70产率的影响。结果表明,复合阳极棒中的Co含量决定了石墨镶嵌Co纳米晶的数量和晶凿直径分布,碳弧法中的He气压力仍是影响掺Co阳极棒所产生的碳  相似文献   
93.
借用傅里叶变换红外光谱(FT-IR)、元素分析(EA)、X射线衍射(XRD)和示差扫描量热分析(DSC)等手段,对比研究了热氧稳定化过程中250℃下时间效应与两种聚丙烯腈(PAN)共聚纤维及其炭纤维结构和性能之间的关联。研究结果表明,PAN纤维在250℃温区内停留超过9min时,最终热氧稳定化纤维的环化度(RCI)、体密度和芳构化指数(AI)的增加速率开始变小;炭纤维的孔含量(Vp)值与内部微晶的d002值开始增大,微晶排列的规整程度变差,缺陷增多,拉伸强度开始降低。  相似文献   
94.
The paper introduces the origin of the word of Direct Digital Manufacturing and other forms of address, and the working principles of Direct Digital Manufacturing technology and major types of the technology, hard- ware and software development, use of materials, applications, market growth and its development prospects. Focused presentations of Direct Digital Manufacturing (additive manufacturing) compared to traditional mechani- cal manufacturing industry in the use of prices, processing speed, reliability and cost advantages and characteris- tics. Particularly the significant challenges and competitiveness of Direct Digital Manufacturing technology in the processing of any complexity created directly the number of objects, internal structure and channel function, as well as the shape of the chassis components and structure of the matching and optimization.  相似文献   
95.
戴梅  张海亮 《流体机械》2007,35(4):77-79
概述了脉幅调制(PAM)和脉宽调制(PWM)技术,在不同的应用场合两种技术有着各自不同的运行方式和原理;分析了PAM和PWM技术的控制原理及应用情况,探讨了其各自的使用场合和优缺点.  相似文献   
96.
该文系统介绍了数字水印的原理和应用方法,并研究了一种基于离散余弦变换(DCT)的数字图像水印算法,并借助MATLAB编程工具,实现数字水印的嵌入、提取和攻击测试。  相似文献   
97.
This essay examines a politically engaged research genre, which follows the biography of the author who founded two journals: one on mathematical models published in English (Quality and Quantity) and one on politically committed social and economic research published in Italian (Inchiesta). The research considered focuses on Italy in the 1950s, the research by Lazarsfeld in Vienna in the 1920s and in the United States in the 1950s and 1960s, and post-1968 politically committed research in Italy. The analysis of such politically committed types of research (all very different from one another in terms of the interpretative model of reality, the methods used and the relations with the tendering party and the people observed) allows one to understand how this kind of research can be performed with very different methods—all of which do, however, seek to modify reality on the grounds of the research results. The metaphor of the crystal and the flame presented by Italo Calvino in order to classify facts and ideas and styles and feelings can also be used to visualise the polarity (and the difficulty/impossibility of contact) that has always been present in sociology between two different tendencies: towards a discipline that offers the most abstract and objective interpretative model of reality possible with the use of mathematical models (the crystal), and, instead, towards a discipline in which an interpretative model of reality is central, one that produces a social change and in which the qualitative and quantitative methods utilised are at the service of this change (the flame). This polarity thus allows us to separate first and foremost all the politically committed research performed by others for different purposes (market research, research to verify some theoretical hypotheses, etc.) but the same polarity also lies within the politically committed research. We can, indeed, identify a type of politically committed research in an area that has, at one extreme, research tending towards the utmost objectivity and scientific quality of the results and where the co-ordinators try to have all the information on the subjects maintaining the greatest possible distance (the subjects must not know they are being observed); at the other extreme, there is a type of research in which the coordinator completely involves the subjects in the gathering of information that will serve to realise a piece of research whose political aims are explicitly shared. For the identification of a sufficiently articulated typology it has been important to consider five dimensions of politically committed research: (a) the characteristics of the research coordinator (his/her belonging to the type and the academic/non-academic professional status) and his/her interpretative model of reality (b) some general characteristics of the research (the tender and funding, the topic choice, the aims, the contributions to the sociological theory, the duration); (c) the research coordinators relations with the political actors (the intensity of the relations, the political use of the research); (d) the relations of the research co-ordinator with the research subjects; (e) the methodological choices (the basic strategies, the methods used, the use of mathematical procedures). The research that exemplifies this typology is all politically committed to the left and was realised in different times and contexts. I start by considering a kind of politically engaged research (co-research) that appeared in Italy in the 1950s; I then analyse two types of politically engaged research realised in Austria at the end of the 1920s and one in the United States in the 1950s; there then follow two kinds of research realised in the 1960s and 1970s in the United States and a further two kinds realised in Italy in the 1970s and early 1980s. In order to have other kinds of research please refer to the two Journals of which I am the editor: one is an English language journal of mathematical models (Quality and Quantity, International Journal of Methodology, founded in 1966 and published today by Kluwer of Amsterdam), and a politically engaged review (Inchiesta, founded in 1971 and still published today by Dedalo of Bari).  相似文献   
98.
针对现有的图像质量评价方法较少利用人眼视网膜和视觉皮层的颜色编码机制,并且未能充分考虑图像色彩信息对图像质量的影响,提出了一种基于多视觉特征的可见光(微光)与红外彩色融合图像色彩和谐性客观评价模型.该模型在图像质量评估中融入了更多的颜色信息,综合考虑多种人眼视觉特征包括视觉对立色彩特征、色彩信息波动特征和高级视觉内容特征,经过特征融合和支持向量回归训练,实现彩色融合图像的色彩和谐性客观评价.采用3种典型场景融合图像数据库进行实验比较与分析.实验结果表明,与现有的8种图像质量客观评价方法相比,所提出的方法与人眼主观感受更加一致,具有较高的预测准确度.  相似文献   
99.
基于小波的继电保护装置电磁干扰软件防护快速算法研究   总被引:2,自引:0,他引:2  
基于Mallat分解的小波变换方法能可靠地检测出电力波形中的奇异点,但不适合于实际工程应用。提出了基于S变换的改进的快速算法,即对AD采样点进行前向差分。对于正常的正弦采样信号,点与点之间的采样点值相差较小,所以差分值也较小;而对于奇异信号,在奇异点附近AD采样值有突变,所以差分值较大。因此,选择合适的差分门槛值就可以检测出信号中的奇异点。分析奇异点附近差分值的正负特性可以检测出该奇异点是正常的故障信号或是受干扰信号。最后,通过对典型波形的仿真计算和实际的电磁兼容性试验,验证了该软件抗干扰措施能显著提高数字式继电保护装置运行的稳定性。  相似文献   
100.
以数字电源控制器的设计方法为研究对象,通过建立数控半桥变换器的环路数学模型,利用MathCAD和Matlab来完成环路开环稳定性的运算和分析,采用Venable III型补偿方法设计出数字PID补偿器。环路补偿实验证明,利用Si8250控制器的直接数字控制方案可以达到很好的环路动态响应和稳定特性。  相似文献   
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