信号时频分析实验设计

介绍了利用VB开发测试技术信号时频分析实验的设计过程，论述了算法实现和软件编程方法，系统可以对测试技术中的周期信号进行动态分解仿真，直观地分析某一周期和频率的时域信号的频率组成以及各频率成分的幅值，自动生成频谱图，从而可以很方便地对信号进行频域描述，提高实验教学效果。     

非平稳信号的时变功率谱与Wigner分布

时频分析旨在构造一种时间和频率的联合密度函数，以揭示信号中所包含的频率分量随时间变化的特性。本文通过对平稳信号相关函数谱分解和wigner分布的研究，给出了非平稳随机信号的时变功率谱，并对其性质进行了详细的研究。     

单片机提高频率测量的精确度

本文介绍了MCS -5 1系列单片机进行频率测量的技术。利用单片机内部高稳定度的标准频率源和定时 /计数器 ,可方便地测量信号的频率和周期。文中给出了测频法和测周法的控制程序 ,根据中界频率还给出了测频与测周软件实现转换的流程图     

100MHz数字频率计的设计

100MHz数字频率计用VHDL语言编程设计,主要由五个模块组成,分别是测频控制信号发生器、十进制计数器、32位锁存器、分频器、动态扫描译码驱动器模块五部分构成.选用分频器将工作时钟分频后,用测频器测频,将被测频率信号经脉冲整形电路后作为计数器的计数脉冲,加入计数器的输入端,测量一定闸门时间内被测信号的脉冲个数,并将其计数值锁存进锁存器中,最后通过动态扫描译码器读出数值,该频率计精度高,可用于频率测量、机械转速测量等领域.     

光栅信号前置处理电路设计

为满足高精密位移测量系统对光栅信号质量的要求,设计了一种光栅信号前置处理电路。利用差分放大电路去除光栅信号中的直流分量。鉴于光栅编码器非恒速的工作特点,利用测频电路对光栅信号进行实时测频,单片机根据光栅信号频率控制数字电位器调整滤波电路参数,改变其通频带以实现自适应滤波。采用数字电位器串并联的方式提高了自适应滤波电路的截频设置精度。实验结果表明,该前置处理电路可以有效地去除光栅信号中的直流分量,对于频率在0～20kHz变化的光栅信号,滤波效果良好,自适应能力强。该光栅信号前置处理电路能够提高光栅编码器的细分精度、环境适应性和可靠性。     

集成电路简易多普勒雷达测速报警器

一、多普勒雷达测速原理简介多普勒雷达的测速原理示意图如图1所示。雷达向运动物体发射约9000MH_2的超高频电磁波信号,当信号在传播过程中被运动物体反射回来时,通过接收反射信号来测量运动物体的速度。根据多普勒效应的理论可知,当运动物体反射电磁波信号时,信号的频率将发生变化。运动物体在电磁波传播方向上的速度越大,信号的频率变化也越大。多普勒雷达就是通过测量发射信号与接收信号经过混频得到的差频信号来测量运动物体的速度。     

二维非平稳信号的小波谱均衡处理方法

小波变换对信号的分时分频的精细表达和多分辨率的全面把握，使我们能更深入地认识信号和噪声的特性，便于基于小波域进行更有效的高分辨率的处理工作；而谱均衡处理技术是提高信号纵向分辨率的有效方法，所以本文提出了将两种方法结合起来共同进行提高二维非平稳信号分辨率．其基本思想是先将二维非平稳信号进行小波分频处理，得到不同尺度的信号；然后将各尺度上的信号分别进行谱均衡处理，再将经谱均衡处理的不同尺度信号进行重建，从而得到高分辨率信号，我们将上述方法称之为小波谱均衡处理．利用提出的新方法进行实际信号处理，处理结果表明该方法的处理效果要好于常规的谱均衡方法，它既能提高二维非平稳信号的纵向分辨率，同时又能保持原信号的固有特征．     

放大自发辐射宽带光源(ASE)谱特性FBG动态解调方法的研究

本文应用超磁致伸缩材料(GMM)构建FBG的电流传感探头,与ASE光源谱特性解调系统共同组成了交流电流测量系统,对50Hz的交流电流进行测量,并通过温度解调传感实验先对ASE光源谱特性解调进行了定标。通过实验标定ASE光源谱特性解调应变灵敏度系数,最终将交流电流形成的布拉格波长漂移量解调成交变的电压信号输出。该信号与输入电流信号相对应,并且包含了输入电流信号的幅值、频率和相位信息。从示波器测得的输入和输出信号的相似性表明,实验结果与理论分析是一致的,验证了ASE光源谱特性动态解调方法的可行性。     

基于MATLAB分析语音信号频域特征

语音信号的频域分析包括语音信号的频谱、功率谱、倒频谱、频谱包络分析等,而常用的频域分析方法有带通滤波器组法、傅里叶变换法、线性参见测法等几种。本文采用傅里叶变换法结合matlab讨论了一段语音信号的短时谱、语谱图、倒谱和复制谱等特征,给出了基音周期及共振峰等仿真结果。     

利用梳状滤波器进行亮度信号与色度信号的分离

<正>流状滤波器,因其幅频特性呈现梳齿状而得名,在一般彩色电视接收机中被用作色度信号两个分量U、V的分离.而亮度信号与色度信号的分离,一般是采用频率分离方式.为了提高图象清晰度,减少亮度和色度信号互相串扰,可利用流状滤波器进行亮度信号与色度信号的分离.下面,就其原理和特点进行分析和讨论.1 传统亮色分离方式的缺陷在一般彩色电视机中亮色分离的原理就是在亮度通道中加入一个陷波器以吸收色度信号,取出亮度信号;在色度通道中加入一个带通滤波器取出色度信号,抑制亮度信号.在这种分离方式下,亮度通道在陷掉色度信号的同时,也将该频率范围内的亮度信号的高频分量吸收掉,从而使亮度信号的高频分量损失,影响图象的清晰度,而且.仍会有色度信号的高次边频分量串入亮度通道,形成图象边缘部分的副载波干扰.色度通道在利用带通滤波器取出色度信号的同时,也取出了处于该通带频率范围内的亮度信号,从而造成亮串色现象,特别是图象出现较多细节或者处于较快运动区域时,由于含有丰富的高频频谱,亮串色现象更加严重,引起明显的彩色失真.     

The relationship between GEAR UP program involvement and Latina/o students’ performance on high-stakes tests

To assess the impact of a college preparation program, district-wide changes in high-stakes test pass rates are examined, followed by an examination of specific program elements that are associated with students’ score changes. Changes in pass rates for districts with and without services are compared for the Latina/o and overall student populations. This study also examines the relationship between hours of participation in various elements of the college preparation program and changes in test scores of low-income Latina/o students. Results indicate that key program elements related to improvements in test scores include participation in mentoring and summer programs.     

Preparing MSW Students for Social Work Licensure: A Curricular Case Example

Licensing has been a dynamic tension for the social work profession for many years, specifically in social work education. Increasingly, social work programs are using factors related to social work licensing (pass rates, number of test takers, etc.) as an indicator of programmatic success. Yet few, if any, published papers examine curricular innovations designed to prepare students for social work licensing exams. This article describes the initiative that one MSW program implemented to address licensing preparedness. After a brief overview of social work licensing, this article describes the contextual rationale, implementation, and evaluation of the Licensing Preparation Initiative (LPI). Since its inception in spring 2011, LPI data suggest that students are more knowledgeable about the process for applying to sit for the exam and the content areas of the exam, more prepared to take the social work licensing exam, and more confident in their ability to pass the social work licensing exam once they graduate. This article concludes with specific strategies and resources for designing a curricular initiative to address licensing preparedness.     

Near‐peer teaching in anatomy: An approach for deeper learning

Peer teaching has been recognized as a valuable and effective approach for learning and has been incorporated into medical, dental, and healthcare courses using a variety of approaches. The success of peer teaching is thought to be related to the ability of peer tutors and tutees to communicate more effectively, thereby improving the learning environment. Near‐peer teaching involves more experienced students acting as tutors who are ideally placed to pass on their knowledge and experience. The advantage of using near‐peer teachers is the opportunity for the teacher to reinforce and expand their own learning and develop essential teaching skills. This study describes the design and implementation of a program for fourth year medical students to teach anatomy to first‐ and second‐year medical students and evaluates the perceptions of the near‐peer teachers on the usefulness of the program, particularly in relation to their own learning. Feedback from participants suggests that the program fulfills its aims of providing an effective environment for developing deeper learning in anatomy through teaching. Participants recognize that the program also equips them with more advanced teaching skills that will be required as they move nearer toward taking on supervisory and teaching duties. The program has also provided the school with an additional valuable and appropriate resource for teaching anatomy to first‐ and second‐year students, who themselves view the inclusion of near‐peer teachers as a positive element in their learning. Anat Sci Educ 2:227–233, 2009. © 2009 American Association of Anatomists.     

A group treatment program for adolescent sex offenders: five steps toward resolution

This article describes a five-step group therapy program for adolescent sex offenders. The key elements of this approach are peer interaction and a system of incentives to move on in therapy, both of which are believed to be crucial in treating adolescents most effectively. While progressing through the steps, the participants acknowledge their adjudication, detail their offenses and personal sexual development, enhance their insights into their behavior and sexuality at large and plan how to avoid offending again. This paper describes the program of a rural outpatient guidance clinic in which a male-female therapist team met with several groups of boys (21 boys). The group program is part of a total treatment approach which also includes assessment, individual and family therapy.     

汽缸套外径加工的自动化改造

为了提高对汽车缸套的无心外圆磨外径加工的加工精度和加工效率,设计了一套针对汽缸套外径的在线监测和上下料机构,采用了电涡流传感器来进行在线监测缸套外径尺寸,在达到尺寸要求时,自动报警,上下料机构自动地将已加工好的汽缸套从工位移开。详述了外径测量方案与系统程序,并分析了可能导致检测误差的相关因素。     

树型视图控件的拖放研究

控件是构造Powerbuilder应用程序界面的基本部件，利用控件和程序代码可以实现界面的强大功能。介绍在PowerBuilder中用树型视图控件的拖放来实现数据窗口中数据的连动显示。     

Dynamic response of functional virtual prototyping of motorcycle under combined excitations

This paper developed 3D product models of motorcycle and engine by UGNX as well as virtual prototyping by ADAMS program with road roughness generated by MATLAB. Under the straight-line running condition, the dynamic responses of motorcycle multibody system to both road and engine excitations were compared with those to only road excitation in terms of vertical acceleration response, amplitude frequency response and power spectral density. The comparisons of simulation data showed that the response due to flat road excitation was around 20 Hz, while that to the combined excitations was in a wide frequency band, of which the major components focused on 10 Hz, 15 Hz, 35 Hz ,70 Hz, 100 Hz and even higher frequencies, reflecting the characteristics of engine excitation based on its unbalanced inertia force and torque. It is concluded that the high fidelity virtual prototyping can simulate the dynamics of motorcycle product well in investigating the vibration and ride comfort performance.     

EXCEL在项目投资决策中的应用

应用EXCEL编制和管理一个项目的数据表格，可以对项目的投资额、生产成本和收入等原始数据进行灵活修改，自动计算出项目财务分析的动态指标，如净现值、内部报酬率、效益成本比和净效益投资比等．且进行项目的敏感性分析也很方便。     

动态规划法在设备更新问题中的应用

在日常工作中,经常涉及到设备更新问题,如何求解设备更新问题非常重要。于是阐述了动态规划方法的基本思想,求解设备更新问题的步骤,并用具体实例和程序,说明了动态规划求解设备更新问题的可行性。