双基地雷达两极区ISAR超分辨成像

由于双基地雷达中两极区双基地角的时变特性,传统ISAR成像法无法获取高分辨的目标像.分析了两极区双基地角的时变性及对距离包络和方位的影响,就两极区目标运动模型中目标方位高次项提出了Radon-TCDS-Relax超分辨成像算法,对每个距离单元进行调频率和调频率变化率搜索并补偿其所对应的方位高次相位误差,用Radon-TCDS-Relax提取散射点实现TCD-RID成像.仿真实验与分析验证了本文方法的有效性.     

高考数学新亮点——统计题

现代社会是一个信息化的社会,人类已经进入大数据时代.日常生活中,数据信息随处可见,因此专门研究如何收集、整理和分析数据的科学——统计学就倍受重视.《普通高中数学课程标准(实验)》(以下简称《课标》)中指出统计的基本思想和基础知识已经成为公民的必备常识.于是,统     

Contributions of the Two Nuclei to the Harmonic Generation in H2＋ Molecules

The separate contributions of the two nuclei in H2＋ to the harmonic generation are investigated by numerically solving the time-dependent Schroedinger equation. The results show that the diverse electron distributions around the two nuclei under the effect of a laser field lead to different contributions of the two nuclei to the harmonic generation in different times, i.e., the contribution mainly comes from nucleus A around the （n ＋ 0.5） optical cycle while from nucleus B around the n optical cycle. By means of the time-frequency distributions and the coupled electron nuclear wave-packet density distributions, the physical mechanism is discussed in detail.     

频率分布直方图中的问题及解法

频率分布直方图中的相关问题是高考中的热点问题.那么,频率分布直方图中到底涉及到哪些问题,又如何求解呢？例1在生产过程中,测得纤维产品的纤度（表示纤维粗细的一种量）共有100个数据,将数据分组如下表：（1）补全频率分布表,并画出频率分布直方图;（2）估计纤度落在[1.38,1.50）中的概率及纤度小于1.40的概率是多少？（3）从频率分布直方图估计纤度的众数、     

主体间“活动”视域下的研讨课如何上——“频率分布表”课例分析

《国家中长期教育改革和发展规划纲要》明确地把“育人为本”作为今后教育教学工作的根本要求,其要求从“以学习为中心”向“以学生为中心”的战略转移,突出课堂教学以“学”之当头,从学生的思、想、惑基本点设计教学,以主体间“活动”实施教学;所以,课堂教学首先要改变“学习本位”“知识第一”的观念,做到“目中有人”,充分激发学生的求知欲和展示欲,努力创设“活动的课堂,开放的课堂”,力争实现课堂教学“把课堂教学的‘话语权’、‘尝试权’、‘生成权’、‘展示权’、‘活动权’交给学生”.本文以“频率分布表”一节为例,频率分布表内容较简单,学生易掌握,一般教师在开设公开课时,都不愿选择这样的课上.简单的问题怎么上?这是新课程理念很关注的教学问题,是需要我们思考和研讨的问题.笔者以“频率分布表”教学研讨活动为例,评析“活动”观下的教学实践.     

Performance of Convolutionally Coded Multicarrier DS-CDMA System

A new convolutionally coded direct sequence （DS） CDMA system is proposed. The outputs of a convolutional encoder modulate multiple band-limited DS-CDMA waveforms. The receiver detects and combines signals for the desired user and feeds a soft-decision Viterbi decoder. The performance of this system is compared to that of a convolutionally coded single carrier DS CDMA system with a Rake receiver. At roughly equivalent receiver complexity, results will demonstrate superior performance of the coded multicarrier system.     

Study on resonance frequency distribution of high-overtone bulk acoustic resonators

Based on the method of characterizing piezo-films by the resonance frequency distributions, the factors influencing the resonance frequency distribution of a High-overtone Bulk Acoustic Resonator (HBAR) consisting of a piezoelectric thin film with two electrodes and a substrate are studied. Some HBARs are simulated. The results manifest that changing the acoustic impedance ratio of the substrate to piezo-film the distribution of the space of the parallel resonance frequency and the effective electromechanical coupling factor are changed. When the fundamental mode of the piezo-film is at high frequency, changing the acoustic impedance ratio of the electrode to piezo-film and the thickness of the electrodes make the resonance frequency distribution of HBARs change. These results manifest that the HBARs can be resonant at specified frequencies by means of adjusting the factors affecting the resonance frequency distribution.     

突破操作过程 突显统计思想——《用样本的频率分布估计总体分布》一课的说课

写在前面2011年湖北省高中青年数学教师优秀课评比暨观摩活动于11月10日在荆州落下帷幕,本次评比活动分为现场讲课和说课两种形式,讲课时间为每节课45分钟,说课时间为15~20分钟.我有幸参加了说课形式的评比,并凭借《用样本的频率分布估计总体分布》一课获得湖北省一等奖.在众多老师的关怀与帮助下,这节课的说课稿经过了多次修改,这一过程让我深刻地体会到打磨     

频数分布直方图要点突破

中考对本部分的考点要求为:理解频数、频率的概念,会列频数分布表,画频数分布直方图和频数折线图,并能解决简单的实际问题. 一、基础知识 (1)频数与频率的概念. 在一组数据中,我们称每个数据出现的次数为频数,而每个数据出现的次数与总次数的比值为频率