高精度调频连续波雷达测距算法的研究

在调频连续波(FMCW)雷达测距算法中,快速傅里叶(FFT)算法频谱分析的误差是由FFT频谱线之间间隔造成的。因此,为了提高FFT算法的测距精度,减少频谱分析的误差,提出了频移补偿的改进措施。频移补偿的频谱搬移因子的获取是利用频谱图对称性与最值和邻近两个谱线点坐标之间的距离差得到的。仿真实验的结果说明,该措施在不大幅提高测距时间的情况下得到的最值更接近实际峰值,可以较好地改进雷达的测距精度。     

一种基于多卷积窗FFT算法的土壤电阻率测量装置研究

采用快速傅里叶变换(FFT)进行土壤电阻率测量分析时很难做到同步采样,存在频谱泄漏现象,影响测量分析的结果。本文提出了土壤电阻率测量装置的FFT加窗算法。研究了基于卷积窗的组合余弦的加窗算法,文中给出了利用所提出的算法进行土壤电阻率测量装置分析的算例,计算结果表明,基于卷积窗的组合余弦加窗算法具有更高的测量分析精度。     

国内18信息移频信号检测频谱校正算法的研究

针对铁路行车安全对轨道电路移频信号检测精度的要求及测试仪表对实时性的要求,分别研究了以快速傅里叶变换(FFT)与线性调频Z变换(CZT)算法为基础的频谱校正方法;采用频谱校正方法,将FFT和CZT变换中存在的频谱泄漏还原为接近无泄漏状态,实现信号参数的准确获取;再从算法原理、误差和运算复杂度等3个方面进行对比性分析,结果表明:对于国内18信息移频信号,在中心频率、低频和频偏的标准值处,使用两种算法得到的各参数计算值的绝对误差分别满足0.2Hz、0.02Hz和0.2Hz;各参数标准值发生一定偏差时,FFT的频谱校正算法的参数检测效果优于CZT的;FFT的复数乘法运算量较小。     

基于有源频谱压缩结构码域发送参考的Chirp超宽带捕获算法研究*

根据Chirp超宽带系统原理和思想,给出了一种基于有源频谱压缩和FFT频域检测的新捕获算法。该算法通过有源频谱压缩将Chirp信号转换成差频信号,再通过FFT进行频偏估计,结合滑动相关判决实现捕获。该捕获方法具有实现结构简单、采样速率低、便于进行通信距离的扩展等优点。理论分析和仿真结果表明了该捕获方法具有很强的实用价值。     

三维向量基快速傅立叶算法

给出了三维向量基快速傅立叶变换（3-D Vector Radix FFT）算法。对三维信号采用基2时域抽取,导出了该算法蝶形运算的一般形式。计算量比较结果显示,三维向量基FFT算法比基于行列分解的三维FFT算法计算量低,计算效率高。     

基于混合卷积窗和双窗法的FFT算法研究

FFT算法是信号处理中一个不可或缺的部分,也是其中需要改进的部分。设计一个精度优良的FFT算法有助于推进频谱分析的实用化进程。针对FFT改进算法的实现需求,文章采用了C语言结构设计了一个任意点数的FFT算法,分析了混合卷积窗的频谱特性,并总结了任意窗函数的幅值恢复方法。最终通过构建混合卷积窗和双窗法结合的处理方法有效提高了FFT算法的精度,仿真结果表明,与普通FFT、混合卷积窗、双窗法方法相比,基于混合卷积窗和双窗法结合的FFT算法具有更高的精度。     

改进的基于FFT pruning 的窄带高分辨率频谱算法

提出一种改进的基于FFT pruning的窄带高分辨率频谱计算方法。该方法是对Sreenivas’s FFT pruning 算法和 Nagai 的利用频移变换的FFT pruning 算法的推广。同时提出输出点分级思想,可实现任意窄带上非2的整数幂次频点输出。该算法比Sreenivas’s FFT pruning 算法具有更小的计算量和更简单的信号流图。     

一种基于全相位FFT的频谱感知算法

为提高能量检测算法的性能,提出一种基于全相位快速傅里叶变换( FFT )的频谱感知算法。全相位FFT中的数据预处理过程,考虑了数据段中心样本点所有可能组合的情况,从而减少因信号截断所导致的频谱泄露,提高谱分析精确度。以能量检测法为例,通过Matlab对基于传统FFT和全相位FFT的频谱感知算法进行理论分析和仿真,结果表明,在信噪比相同的条件下,后者的谱间干扰较小,信号的误检率较低;在相同虚警率的条件下,后者可使频谱泄露得到有效抑制,获得的频谱更接近于真实的频谱信息,检测概率相应提高。因此,全相位FFT能量检测法的检测性能明显优于传统能量检测法。     

Hanning窗在电力系统谐波分析中的应用

采用FFT算法对电网信号进行谐波分析时很难做到同步采样和整数周期截断,由此造成的频谱泄漏和栅栏效应将影响到谐波分析的结果。本文应用矩形窗和Hanning窗的加窗插值FFT算法分析非同步采样的电力系统谐波,经过MATLAB仿真证明：采用基于Hanning窗的加窗插值FFT算法能够大幅度降低由非同步采样造成的误差,最后给出了实现该算法的C语言程序。     

基于特征参量的电流识别装置设计

实现了利用STM32H743单片机和自行设计的信号处理电路识别不同用电器的装置设计。运用信号处理算法可以对各种电流信号进行时域到频域的转换,通过对频谱进行分析,得到电流信号在频域内的特征参量,进而区分出不同的电流信号。选用快速傅里叶变换(fast fourier transform,FFT)算法,以STM32H743单片机作为算法实现工具,对7种不同用电器的工作电流进行频谱分析,进一步识别用电器的工作状态。每次测试时只有单件用电器工作,识别效果良好。     

Toward the light field display: autostereoscopic rendering via a cluster of projectors

Ultimately, a display device should be capable of reproducing the visual effects observed in reality. In this paper we introduce an autostereoscopic display that uses a scalable array of digital light projectors and a projection screen augmented with microlenses to simulate a light field for a given three-dimensional scene. Physical objects emit or reflect light in all directions to create a light field that can be approximated by the light field display. The display can simultaneously provide many viewers from different viewpoints a stereoscopic effect without head tracking or special viewing glasses. This work focuses on two important technical problems related to the light field display; calibration and rendering. We present a solution to automatically calibrate the light field display using a camera and introduce two efficient algorithms to render the special multi-view images by exploiting their spatial coherence. The effectiveness of our approach is demonstrated with a four-projector prototype that can display dynamic imagery with full parallax.     

Design applications of the MIDAS graphics system

midas is a versatile system of fortran-callable subroutines developed for the modular design and device-independent display of two- and three-dimensional graphics compositions. The system is primarily oriented toward applications involving the definition and spatial transformation of three-dimensional line drawings. The graphics generated by midas consist of three-dimensional line segments mapped onto any graphics device with vector-drawing capabilities.This paper presents an application of midas in architectural and civil engineering design. A fortran monitor program has been written to provide a concise command structure for planar design and display. This command structure allows the user to interactively build, transform, store, retrieve, and display three-dimensional planar compositions. Output displays may optionally have hidden lines removed. An example structure (the University of Colorado Computing Center) is modularly designed, edited, and displayed. Finally, a discussion of the advantages and shortcomings of midas as a design tool is given along with suggestions for further improvement of the system.     

Cutting on triangle mesh: local model-based haptic display for dental preparation surgery simulation

A new method to realize stable and realistic cutting simulation using an impedance display haptic device and microcomputer is presented in this paper. Material removal or cutting simulation is a critical task in dental preparation surgery simulation. In this paper, a piecewise contact force model is proposed to approximately describe the cutting process. Challenging issues of minimizing the difference between the cutting simulation and haptic contact simulation are analyzed. The proposed contact-based simulation method is developed for a one-dimensional cutting task and can be expanded to three-dimensional cases. Local model-based multirate simulation cutting architecture is proposed and force control of the haptic device is decoupled from the cutting simulation loop, which can both ensure high fidelity of dynamical simulation as well as maintain stability of the haptic device. The cutting operation is realized using spherical and cylindrical shaped tools. An experiment based on the Phantom desktop proves that fidelity in one-dimensional cutting can be realized and stability in three-dimensional cutting can be ensured using the force-filtering method.     

Anthropometric measurements of the female perineum for design of the opening shape of urination device

This study measured the anthropometric characteristics of the perineum among Chinese young women. The three-dimensional surface of the perineum was reconstructed to design an opening shape for a female urination device. Twenty-four young healthy females participated in this study. The width of the perineal furrow, the diameter of the ischial tuberosity, the distance from the exterior urethral opening to the anus, the distance from the exterior urethral opening to the tuberosities, and the distance from the tuberosities to the anus were measured using the Martin measurement approach. The perineum was then scanned using a three-dimensional scanner with raster display technology. The scanned data were used for three-dimensional shape reconstruction. From the measurements, three types of relative positions among the exterior urethral opening, ischial tuberosity, and anus were discovered. The results from this study not only advance our understanding of the anthropometric measurements of the perineum but also provide anthropometric information for the design of the opening shape of a female urination device.Relevance to industryThe anthropometric data collected in this work provide urination device designers with data for the length, width, and curvature of the perineum for the surface design of the opening part of female urination devices. The relationship between female urination devices design and perineum size proposed in this paper can provide design guidelines.     

耙吸挖泥船疏浚中三维地层剖面的设计与实现

提出一种三维地层剖面的实时显示方法。该方法利用给定的数字高程模型数据及三次样条函数拟合曲线构造剖面轮廓线,以有效解决三维地层模型内部的可视化问题。为便于施工,在疏浚过程中采用声纳数据动态调整模型。实验结果表明,该方法计算速度快、精度高,可以达到实时显示的效果,并能提高耙吸挖泥船疏浚的质量,减少对环境的影响。     

A novel diffractive backlight concept for mobile displays

Abstract— Power‐efficiency demands on mobile communications device displays have become severe with the emergence of full‐video‐capable cellular phones and mobile telephony services such as third‐generation (3G) networks. The display is the main culprit for power consumption in the mobile‐phone user interface and the backlight unit (BLU) of commonly used active‐matrix liquid‐crystal displays (AMLCDs) is the main power drain in the display. One way of reducing the power dissipation of a mobile liquid‐crystal display is to efficiently distribute and outcouple the light available in the backlight unit to direct the primary wavelength bands in a spectrum‐specific fashion through the respective color subpixels. This paper describes a diffractive‐optics approach for a novel backlight unit to realize this goal. A model grating structure was fabricated and the distribution of outcoupled light was studied. The results verify that the new BLU concept based on an array of spectrum‐specific gratings is feasible.     

脑血管体绘制的快速表意式增强

利用3维可视化技术重构脑血管模型,获取脑血管及其相关组织的立体结构,对于辅助诊断脑血管疾病具有重要意义.鉴于脑血管位置的特殊性、形态的复杂性及灰度信息的多变性,要求重构技术能够清晰还原其空间结构.基于CUDA(computed unified device architecture)的光线投射体绘制,引入深度和轮廓宽度等因子,采用基于曲率的轮廓增强、基于深度的边界增强以及基于立体显示和颜色融合的深度线索提示等表意式技术,实时重构高质量3维血管模型,生动展现脑血管的3维结构信息,如深度、梯度、观察方向等.实验结果表明,本文方法的有效性,在精确显示脑血管结构的同时能够增强体绘制效果.     

KAT II: Tactile Display Mouse for Providing Tactile and Thermal Feedback

This paper proposes a tactile display mouse providing both pin-array-type tactile feedback and thermal feedback. The pin-array-type tactile display is composed of a 6 × 5 pin-array that is actuated by 30 piezo-electric bimorphs. Micro shape and vibrotactile feedback can be generated by the device, and various planar distributed patterns can be displayed as can Braille cell patterns. The thermal feedback device is composed of a thin-film resistance temperature detector, a Peltier thermoelectric heat pump and a water cooling jacket. Users can discriminate among different materials by considering the temperature variation that can be sensed as they touch an object's surface. This paper also includes an experimental evaluation of the tactile display mouse to prove the effectiveness of displaying textures. Evaluation of the ability to identify material properties was conducted using the thermal feedback part that displays a simulated temperature profile. To investigate thermo–tactile interaction, an experiment determining perceived magnitude of vibrotactile stimulus according to different temperature conditions was conducted.     

Web模式的医学断层图像三维重建

实现了基于Web的医学图像三维重建及显示.用超高速CT扫描获得人体器官的二维图像,基于JavaApplet与JavaApplication编程,采用体绘制法完成二维图像的三维重建与显示.重建实现了在Internet上以Web模式跨平台运行.重建的三维图像能够清晰地显示人体器官的解剖结构,尤其是心脏的整体形态及冠状动脉的走向.用JavaApplet与JavaApplication实现基于Web的医学图像三维重建是可行的,并对三维图像的临床应用起到了推动作用.通过三维重建显示人体器官的立体形态,尤其是冠状动脉的解剖结构,在临床上具有很大的参考价值.     

Simulation reality and stereotype strength: A problem for equipment designers

In designing human–machine interfaces, it may be necessary for designers to simulate the interface in order to find an acceptable arrangement of controls and displays which have a high expectancy of the relationship between these. We report experiments aimed at determining the level of simulation required to obtain valid measures of stereotype strength relating control movement to display movement. Two experiments are reported, using devices of apparently low and high complexity. Low complexity devices were similar to electronic devices that might be used in the home; the chosen high complexity device was a crane control cabin. For two-dimensional control/display arrangements a low level of simulation generally gave valid results for stereotype strength; a high level of simulation is required for three-dimensional arrangements. With the more complex crane control system, there was a strong effect of the control layout, but little effect of the level of simulation: paper/pencil tests performed as well as computer simulation in giving stereotype strengths. Implications for designers are discussed.