Inductorless Ultra-Wide Band Front-End Chip Design with Noise Cancellation Technology for Wireless Communication Applications 10

An inductorless Ultra-Wide Band(UWB)receiver front-end chip design used in wireless communications for the frequency band of 3.1～4.8 GHz is presented.This homodyne receiver mainly consists of a differential Low Noise Amplifier(LNA)circuit followed by a down-converting mixer.The proposed LNA circuit with a noise canceling resistor is connected to the CMOS device's body to reduce the substrate thermal noise.Simulation and measurement results show that the chip can reduce the front-end Noise Figure(NF)about 0.5dB and achieve the Conversion Gain(CG)of 19.44～21.57 dB and double-sideband NF less than 7.8 dB.Also,the input third-order intercept point(IIP3)is-11 dBm,and the input second-order intercept point(IIP2)is 49 dBm.Fabricated in TSMC 0.18 μm CMOS technology,this chip occupies only 0.167 mm2 and dissipates power 59.2 mW.     

基于自适应噪声抵消的永磁同步电机高频注入信号检测

在永磁同步电机的控制中,无论是矢量控制还是直接转矩控制,都需要适时精确知道转子位置的信息。论文探索性地提出用自适应噪音抵消技术对永磁同步电机的高频电流响应信号进行检测和处理,利用噪声信号和原始被测信号不相关的特点,自适应地调整滤波器的传递特性,将噪声干扰抑制或大幅衰减,提高有用信号的信噪比,以获得正确的转子位置信息。     

机床变速箱噪声估算公式的探讨

提出单级齿轮传动的噪声计算公式，对多级齿轮传动变速箱辐射的噪声可用多声源声压级ｄＢ（Ａ）合成公式逐级进行综合，所得的估算值与实测值相当接近。     

离心式通风机噪声机理及设计与改造中的降噪方法综述

对离心式通风机噪声产生的机理进行了分析 ,并重点讨论离心式通风机在设计与改造中几种常用的降噪方法。可为离心风机降噪设计和降噪结构改造提供参考。     

OFDM水声通信系统语音信号的小波包消噪方法

在阐述和构造了正交频分复用（OFDM）水声通信系统的基础上,利用小波包分解与重构对OFDM水声通信系统进行语音信号消噪处理。小波包分解方法依据信号与噪声小波变换系数分布特性不同来进行,首先将语音信号分层,确定最佳小波包分解树,再进行阈值量化,完成小波包分解,并对所得阈值进行消噪处理,最后利用小波包逆变换重构传输信号。计算机仿真结果表明在OFDM水声通信系统中利用小波包分解方法对语音信号进行处理,可有效消噪,并可较为完整地保存有效信号。     

低噪声齿轮设计方法（一）

从分析啮合冲击入手，通过科学合理地选择齿轮设计参数，使啮合齿轮的啮入冲击速度降至最低。啮出冲击速度与啮入冲击速度的比值处于某一数值范围，减小或避免啮合节圆冲击，可明显降低齿轮传动噪声，此法不涉及齿轮加工设备，容易实施应用，文章提供了啮入，啮出冲击速度的计算公式以及齿轮参数优化设计的目标函数和约束函数。     

降低CGH再现像量化噪声的新方法

报道了一种降低计算全息图（ＣＧＨ）再现像量化噪声的一种新方法,它在原有罗曼Ⅲ型计算全息的基础上,在取样点数相同的前提下,利用显示器的固有分辨率,将全图分解成多幅子图作出,再应用图像处理软件重新拼接,从而降低了再现像量化噪声,文中给出了实验结果     

叶轮扭振引发离散气动噪声理论计算模型研究

对叶轮振动模态进行分析 ,表明由于叶片刚度远小于轮毂的刚度 ,叶轮振动以叶片振动为主 ,而叶片振动低频表现为扭摆振动 ,高频表现为表面弯曲波振动。低频振动对叶轮气动噪声影响很大 ,本文基于Lowson离散噪声模型对叶片扭振引发离散气动噪声声压的估算公式进行了推导 ,为工程应用提供了方便     

A nonlinear technique based on fuzzy models for the correction of quantization artifacts in image compression

A simple technique for the restoration of color images degraded by lossy compression is presented. The proposed approach deals with the YIQ color space and processes the luminance component by means of a recursive algorithm based on fuzzy models. This design choice combines effectiveness and simplicity. Indeed, the method can satisfactorily reduce quantization errors produced by lossy compression such as the popular JPEG technique. On the other hand, the tuning process is very fast because it requires one parameter only.     

高压风机机壳声振分析及数值模拟

采用有限元方法和边界元方法建立了9-19 5A型风机结构辐射噪声预测模型,可用于计算辐射声功率、固体声和辐射效率等声场特性参数.对风机机壳进行了模态分析和噪声预测.为风机噪声优化设计打下了良好的基础.     

数字式多通道语音通信记录的一种新方法

传统的多通道通信记录设备是由模拟磁带机或数字磁带机构成，设备庞大复杂，价格高昂。随着语音压缩技术迅猛发展，码激励线性预测语音编码（CELP）、多带激励语音编码（MBE），都能在低比特率下，获得和市内电话长途电话大致相同的话音质量。因此，以PC机和海量存储器（硬盘）为核心，以软件为主体的全数字式多通道语音通信记录设备应运而生。叙述了方案的构成，实现该方案的关键技术和开发的实验样机的初步结果。     

数字式镜像组合干扰抑制技术及其在测量仪器中的应用

本文提出了一种对仪器信道输入中的被测信号及其镜频干扰信号进行直接采样,然后采用数字混频、滤波、移相处理,进行镜频对消的抑制技术,信道可以获得高Q值、锐截止特性的镜频抑制能力,并且可避免信号幅相失真。在相关仪器中应用此技术,可以降低高频级滤波难度,简化系统构成。本文依此设计了一种实验方案并给出了仿真结果     

薄板结构低噪声仿生拓扑优化方法

针对薄板结构的低噪声设计问题,以结构声辐射功率最小化为优化目标,借鉴植物脉序分枝结构的构型特征,提出了薄板结构加强筋布局的仿生拓扑优化方法。以结构应变能最小和释放局部最大剪应力作为加强筋主脉和次脉的生长准则,以广义Murray准则作为加强筋脉序的分歧准则,构造了具有脉序分级特征的加强筋自适应生长算法。以固支薄板结构的横向弯曲振动及声辐射问题为典型算例,对比分析了仿脉序分布加筋板结构的声辐射功率和振动功率流的分布特性。数值结果表明,与相同体积约束下的正交加筋布局方式相比,仿脉序分布加筋方法使薄板结构具有更优的声振特性,进而验证了薄板结构加强筋仿生布局降噪方法的有效性与可靠性。     

A New Approach to Cleave MEMS Devices from Silicon Substrates

Dicing of fabricated MEMS （microelectromechanical system） devices is sometimes a source of challenge, especially when devices are overhanging structures. In this work, a modified cleaving technique is developed to precisely separate fabricated devices from a silicon substrate without requiring a dicing machine. This technique is based on DRIE （deep reactive ion etching） which is regularly used to make cleaving trenches in the substrate during the releasing stage. Other similar techniques require some extra later steps or in some cases a long HF soak. To mask the etching process, a thick photoresist is used. It is shown that by applying different UV （ultraviolate） exposure and developing times for the photoresist, the DRIE process could be controlled to etch specific cleaving trenches with less depth than other patterns on the photoresist. Those cleaving trenches are used to cleave the wafer later, while the whole wafer remains as one piece until the end of the silicon etching despite some features being etched all the way through the wafer at the same time. The other steps of fabricating and releasing the devices are unaffected. The process flow is described in details and some results of applying this technique for cleaving fabricated cantilevers on a silicon substrate are presented.     

A Bayesian paradox and its impact on the GUM approach to uncertainty

The paper presents ideas and observations about the use of the frequentist and the Bayesian approach to estimation and uncertainty. The merits and the pitfalls of the Bayesian approach, compared with the frequentist one, are illustrated using a simple example, which gives rise to an instructive paradox. The impact of the paradox on the GUM approach to uncertainty prescribed in Supplement 1 is highlighted and discussed.     

From Allan Variance to Phase Noise: A New Conversion Approach

A new mathematical method is proposed to convert the oscillator instability parameters from Allan variance to Spectrum Density(SD)of random phase fluctuations,which is the inversion of the classic transformation formula from SD to Allan variance.Due to the fact that Allan variance does not always determine a unique SD function,power-law model of the SD of oscillator phase fluctuations is introduced to the translating algorithm and a constrained maximum likelihood solution is presented.Considering that the inversion is an ill-posed problem,a regularization method is brought forward in the process.Simulation results show that the converted SD of phase fluctuations from Allan variance parameters agrees well with the real SD function.Furthermore,the effects of the selected regularization factors and the input Allan variances are analyzed in detail.     

A Finite Element Approach to Modeling Abrasive Wear Modes

Machine components operating in sandy environments will wear because of the abrasive interaction with sand particles. In this work, a method is derived to predict the amount of wear caused by such abrasive action, in order to improve the maintenance concept of the components. A finite element model is used to simulate various tips scratching a smooth surface. The model is verified by comparing the obtained results with a set of experiments performed earlier (M. Woldman, et al., 2013, Wear, 301(1–2), pp 76–81).     

一种时间工作流模型的启发式分析方法

立足于实际业务过程对工作流系统时间管理功能的需求，提出了一种新的工作流时间建模与分析方法。为工作流网的元素扩展时间属性建模业务过程的时间因素；讨论了时序业务环境中活动的可调度分析，给出了时序一致性验证方法；提出了启发式可调度性分析方法，用于验证某一给定工作流实例执行的时间可行性。研究结果表明，所提方法不仅支持业务过程的时间约束规范与验证，还对丰富工作流时间建模理论具有重要意义。     

Novel approach to the semi-empirical universal theory for secondary electron yield

The universal semi-empirical equation has been commonly used to quantitatively describe the energy dependence of the secondary electron yield (SEY). It is even used as a first reliability test for experimental data. The equation is based on the assumption that the stopping power is constant along the electron trajectory. In this article, we derive a novel analytical expression based on a more advanced model which considers linear stopping power dependence on penetration depth. Although coinciding with the universal equation at low energies, the novel function has lower intensity in the higher energy range. The models were compared with experimental SEY data of different metals, taken from literature, as well as freshly cleaved highly oriented pyrolytic graphite, measured in the frame of this work. It is confirmed that the novel expression better describes the experimental data.     

复杂零件结构设计的概念单元方法

提出复杂零件结构设计的概念单元方法,即几何与物理模型、概念构型与单元、强度与刚度、工艺与造型四部分。分析了复杂零件的应用场合和结构特点,建立几何实体与物理模型,包含联接与安装部位,设置工况载荷与约束,定义设计区域与非设计区域;采用结构拓扑优化方法获得在若干工况下零件实体内部的传力路线,综合多工况下传力路线和相关因素,构造出复杂零件结构的概念模型,并结合零件的载荷形式,综合考虑制造工艺性,选择合适的零件结构单元;依据零件的强度或刚度要求,使零件壁板和结构单元具有满足性能要求的尺度;同时,兼顾零件结构工艺性和视觉美学效果等因素,对零件结构形状和尺度进行工艺和造型再设计;以加工中心立柱和三级齿轮减速器箱体为例展示了结构设计过程,通过合理布置零件内部筋板、单元的结构形式和尺寸,为复杂零件的轻量化和科学合理结构设计提供有效方法。