WVD和XWVD的统计特征分析   总被引：4，自引：0，他引：4  

陈光化  曹家麟 《上海大学学报(英文版)》2003,7(4):379-383

1　Introduction　TheWigner Villedistribution (WVD) [1 7] hasbeenshowntobeefficientintheestimationofinstanta neousfrequency (IF)ofasignal.BecauseWVDisofbettertime frequencyresolutionandabletolocateen ergybasedontheIFlaw ,especiallyforalinearfre quencymodulated(LFM )signalwithaconstantampli tude,WVDwillreducetoarowofdeltafunctions .ThereforeonecanobtainanunbiasedestimateofIFofthesignalusingthepeakofWVD .Butperformanceofthepeakestimatorisdegradedsignificantlywithesti mationvariance quic…  相似文献   

Study on dynamic response of embedded long span corrugated steel culverts using scaled model shaking table tests and numerical analyses     

车爱兰  葛修润 《浙江大学学报(A卷英文版)》2006,7(3):430-435

INTRODUCTION On Jan. 17, 1995, the Hyogoken-nanbu earth-quake in Kobe, Japan, caused great destructive and damage to underground structures, such as subway structures, mountain tunnels, multipurpose under-ground ducts and other underground structures, which had previously been considered to be resistant to earthquake effects (JSCE, 1996; ECRHAED, 1998). This earthquake revealed that a number of critical issues should be added in the seismic design and seismic strengthening of undergr…  相似文献   

建国初期教育制度变迁与私立高等教育消亡过程   总被引：1，自引：0，他引：1  

李立匣 《清华大学教育研究》2005,(Z1)

新中国成立后的一项重要任务是有计划有步骤地改造国民政府留下的旧教育,而对私立大学的改造是其中的重要内容。本文在调查相关历史资料的基础上,从新制度主义关于制度变迁的理论视角,分析了私立高等教育制度瓦解的制度性因素。即新中国政府出台的系列政策和措施成为改造的基本依据;不断加强对师生的思想改造,树立起新民主主义教育的文化认知;而私立大学组织内部的改造是思想、政策落实的具体反映。  相似文献   

排序抽样的非参数估计     

董晓芳  宋向东  张良勇  郭照庄 《邢台学院学报》2006,21(2):95-96

针对未知对称分布函数提出新的非参数估计量,并证明了此估计量一致优于文献[1]给出的估计量.  相似文献   

试论诗歌语言的变异性     

蒋德均 《涪陵师范学院学报》2006,22(6):50-56

诗歌语言是一种变异性的艺术语言。从语言的组合和结构形式上来看,诗歌语言是对常规语言的超脱和违背,同时也是一种创造和发展。它与常规语言相比较,在语音、语义、语法等方面都存在着较大的变异性。正因为它的变异,使之更具诗性,成为诗歌区别于其它文体的重要特征之一,是诗之所以为诗的主要标志。  相似文献   

黔江方言初探     

汪增阳 《涪陵师范学院学报》2001,17(4):75-79

大量的民族语言存在于方言土语之中。面对民族语言日渐消逝的现实，对其进行调查研究显得十分重要。本以重庆市黔江区马喇湖的方言土语为个案，初步探讨土家语、苗语、汉语之间融合、遗传变异的情形，为多民族地区语教学提供新视点，澄清对黔江地区少数民族的一些模糊认识。  相似文献   

关于军用飞机着陆灯专用电源设计方案的定量计算     

谢东藩  陈惠桐 《金陵科技学院学报(社会科学版)》2003,18(1):12-14

10 0 0 W军用飞机着陆灯的灯丝是一种非线性时变电阻 ,冷电阻极小 ( 0 .0 4Ω左右 ) ,工作几秒钟后才能达到额定阻值 ( 0 .9Ω ) ,在对该灯进行老炼及检测时 ,如何仿真飞机着陆时迅速点亮的实际情况 ,是设计这种专用电源的一大难题。本文运用非线性时变电阻理论和金陵职业大学电源专利技术 ,进行了分析和定量计算 ,成功地解决了这一难题  相似文献   

竖直平面内圆周运动的临界速度问题     

毕玉凤 《唐山师范学院学报》2005,27(2):47-48

对竖直平面内圆周运动的临界速度进行了讨论，并对没有支撑物的物体在竖直面内做圆周运动的临界问题、有支撑物的物体在竖直面内做圆周运动、特殊条件下的物体在竖直面内做圆周运动的临界问题分别进行了举例分析。  相似文献   

论安徽经济增长中的产业结构演变     

包先建  付文林 《安徽师范大学学报(人文社会科学版)》2002,30(4):415-418

立足于安徽经济增长与产业结构演变的历史,从供给与需求两个方面对安徽三次产业的发展状况、发展中存在的制约性因素进行了比较全面的分析,作者认为调整安徽产业结构,需要建立正确的结构调整思想,实行非均衡发展的赶超战略,当前特别需要注重制造业和农副产品加工业发展,为第三产业发展创造社会需要基础,拉动经济增长,促进第一产业劳动力转移.  相似文献   

Teachers’ motives for learning in networks: costs,rewards and community interest     

Antoine van den Beemt  Evelien Ketelaar  Isabelle Diepstraten  Maarten de Laat 《Educational research; a review for teachers and all concerned with progress in education》2018,60(1):31-46

Background: This paper discusses teachers’ perspectives on learning networks and their motives for participating in these networks. Although it is widely held that teachers’ learning may be developed through learning networks, not all teachers participate in such networks.

Purpose: The theme of reciprocity, central to studies in the area of learning in networks, is often approached from a rational exchange perspective. This study attempts to extend this approach with reference to the concept of symbolic interactionism. The study was guided by the following research question: What is the relationship between teachers’ perceptions of learning networks and their motives for participation or non-participation in these networks?

Design and methods: In order to address this research question, semi-structured interviews among 25 teachers in secondary education in the Netherlands were carried out. The semi-structured interviews consisted of three parts: background information, perspectives on learning networks and personal experiences with those networks. Data were analysed qualitatively and analyses consisted of within-case analysis, and cross-case analysis of interview fragments. Three themes were considered: (1) perspectives on learning networks, (2) motives for participation perceived as rational exchange, (3) motives for participation perceived as related to social order.

Findings: The findings are presented around these three themes. Each theme is discussed in relation to relevant aspects from the literature. Findings indicated that teachers perceived learning networks to be organised both within-school and outside school, and mostly focused around specific content knowledge. Reasons for participation or non-participation were related to rational costs and rewards (such as time, technology, self-efficacy); in symbolic motives (such as joy, sharing and mutual understanding), and also in a sense of meaning that resulted from networking activities.

Conclusions: We conclude that, in addition to social exchange motives, the data suggest that symbolic aspects of communication and interaction play an important role in considerations for participation in learning networks. This may be described in terms of four ‘types’ of networking teachers: the Community focused networking teacher, the Locally focused networking teacher, the Not-yet-networking teacher, and the Non-networking teacher. It is hoped that these exploratory findings could be helpful in supporting the development of learning networks for all teachers.  相似文献