基于μC/OS-Ⅱ的高精度超声波测距系统设计

介绍一种以ARM处理器LPC2138为核心,采用超声波回渡信号的A/D采样检测原理,实时测距,液晶屏显示的便携式系统.该系统利用ARM处理器处理速度快的优点.自行处理A/D采样速度.系统的测距范围在0.1～4.5 m内,测量精度为1 cm,实时性好,准确方便,有较高的推广价值.     

基于STM32的全相位FFT相位差测量系统

针对军用和民用工程领域信号相位差测量的需要,基于全相位测量理论,使用ARM公司的高性能32Bit CortexM32内核处理器STM32F103,设计并制作了一个低成本,结构简单,处理速度快而有效的相位差测量系统,通过采样了127个点,处理后做64个点的FFT,实现了信号相位差的测量.测试结果表明有效分辨精度为1度.     

基于ARM处理器多普勒智能灯控系统的设计

描述了一种运用多普勒效应,基于ARM处理器实现的智能灯光控制系统。该系统利用ARM处理器的定时器输入捕获功能测量信号的多普勒频率,通过计算模型获得移动物体的速度,并预测其位置,控制灯光的点亮和持续时间,从而达到智能灯光照明控制,在提供照明的同时又可以节约电能,并可通过显示屏显示动态测量结果。     

基于ARM9的远程频率采集系统设计

介绍了一种频率信号采集系统的设计.硬件以ARM嵌入式处理器S3C2440和10/100M bit/s自适应的以太网接口DM9000为核心.主要包括信号采集、频率测量、嵌入式处理系统、以太网接口等部分.软件采用嵌入式μCLinux操作系统,通信使用TCP协议.系统具有强大的网络支持功能.数据可通过以太网与远程故障诊断中心进行传输.     

基于ARM的温度监控系统设计

提出了一种实时操作系统,采用高速ARM嵌入式微处理器和数字温度传感器(DS18B20)进行的温度采集及监测实验.文中主要采用嵌入式实时操作系统Windows CE作为软件平台,用低功耗、高性能的Samsung公司的32位ARM微处理器S3C2440为主控芯片,以TE2440开发板作为硬件平台,设计了一个温度监控系统.其主要功能模块有温度信号采集模块、ARM控制模块、数据读取模块和显示模块.整个系统使用windows ce操作系统下的EVC编译软件进行设计,采用C++语言编程实现数据的采集、读取、传输以及LCD显示,设计灵活,调试简单.     

基于μC/OS-Ⅱ的高精度超声波测距系统设计

介绍一种以ARM处理器LPC2138为核心,采用超声波回波信号的A/D采样检测原理,实时测距,液晶屏显示的便携式系统。该系统利用ARM处理器处理速度快的优点,自行处理A/D采样速度。系统的测距范围在0.1～4.5 m内,测量精度为1 cm,实时性好,准确方便,有较高的推广价值。     

基于ARM的简易数字示波器设计

系统提出一种基于嵌入式ARM7微处理器的简易数字示波器的设计与实现方案。以ARM7微处理器为控制核心,高速A/D器件TLC5510采集信号,实现信号的存储与测量。使用彩色液晶屏显示信息内容丰富,人机界面好。系统软件采用模块化、层次化结构易于维护和扩展。     

基于ARM的船舶双轴系扭振测量仪设计

为了对船舶轴系双通道扭振进行测量,提出了一种基于ARM和RTX操作系统的扭振测量仪的设计。该设计以高性能ARM处理器LPC1788为核心,利用TT10K扭矩遥测系统,A/D转换器,信号前端处理模块实现振动信号的高速精确采集。将采集到振动信号的时域图形显示在LCD上。在ARM上加上RTX操作系统,可有效实现对上位机下达任务和板载资源的管理。     

基亏μC／OS-Ⅱ的高精度超声波测距系统设计

介绍一种以ARM处理器LPC2138为核心,采用超声波回波信号的A／D采样检测原理,实时测距,液晶屏显示的便携式系统。该系统利用ARM处理器处理速度快的优点,自行处理A／D采样速度。系统的测距范围在0．1-4．5m内,测量精度为1cm,实时性好,准确方便,有较高的推广价值。     

基于无线传感网络的智能安防系统

本文所提出的安防系统通过温度感知和红外探测并实施报警,实现室内防火防盗。系统采用ZigBee和ARM相结合,传感器输出的信号经过处理由支持ZigBee的无线传输模块传至ARM处理器模块,实现前端信号与后端控制器之间的无线连接。ARM经过对所采集数据的分析,报警时能够通过GPRS以短信形式通知相关人员,实现远程监测。     

基于ARM的矿用便携式多参数气体检测仪的设计

针对目前煤矿常用气体检测仪以检测单气体为主,检测精度不高、稳定性不强等问题,研究并设计了一种基于ARM9的便携式多参数气体检测仪。本检测仪以S3C2440A微处理器为核心控制器,可以实现CH4、CO、H2S、O2四种气体浓度的实时检测,同时,检测仪移植了Linux嵌入式操作系统,提高了系统的可靠性和稳定性。实际应用表明,该检测仪携带方便,测量准确,将井下气体信息浓缩于一掌之中,使井下生产人员能及时有效的获得矿井安全状况,具有较高的推广应用价值。     

浅谈溶液电导率的测量

在溶液电导率的测量中,常常由于电导率仪温度补偿不准引起测量误差,文章提出一种新的测量方法,减少了因温度补偿不准引入的测量误差.     

Strongly Anisotropic Thermal Conductivity of Free‐Standing Reduced Graphene Oxide Films Annealed at High Temperature

Thermal conductivity of free‐standing reduced graphene oxide films subjected to a high‐temperature treatment of up to 1000 °C is investigated. It is found that the high‐temperature annealing dramatically increases the in‐plane thermal conductivity, K, of the films from ≈3 to ≈61 W m^?1 K^?1 at room temperature. The cross‐plane thermal conductivity, K_⊥, reveals an interesting opposite trend of decreasing to a very small value of ≈0.09 W m^?1 K^?1 in the reduced graphene oxide films annealed at 1000 °C. The obtained films demonstrate an exceptionally strong anisotropy of the thermal conductivity, K/K_⊥ ≈ 675, which is substantially larger even than in the high‐quality graphite. The electrical resistivity of the annealed films reduces to 1–19 Ω □^?1. The observed modifications of the in‐plane and cross‐plane thermal conductivity components resulting in an unusual K/K_⊥ anisotropy are explained theoretically. The theoretical analysis suggests that K can reach as high as ≈500 W m^?1 K^?1 with the increase in the sp² domain size and further reduction of the oxygen content. The strongly anisotropic heat conduction properties of these films can be useful for applications in thermal management.     

Low-Temperature Transport Properties of Sn<Subscript>24</Subscript>P<Subscript>19.3</Subscript>Br<Subscript>8</Subscript> and Sn<Subscript>17</Subscript>Zn<Subscript>7</Subscript>P<Subscript>22</Subscript>Br<Subscript>8</Subscript>

We report on temperature-dependent thermal conductivity, resistivity, and Seebeck coefficient of two polycrystalline Br-containing Sn-clathrate compounds with the type I crystal structure. Interstitial Br atoms reside inside the polyhedral cavities formed by the framework, resulting in hole conduction. The framework bonding directly influences the transport properties of these two compositions. The transport properties of these two clathrates are compared with those of other Sn-clathrates. We also discuss our results in terms of the potential for thermoelectric applications.     

Electrical conductivity and photoluminescence of diamond films grown by downstream microwave plasma CVD

Electrical conductivity measurements and photoluminescence (PL) were used to study the effects that sample distance from the plasma during growth has on the carrier transport properties of undoped CVD diamond. The films were grown by downstream microwave plasma chemical vapor deposition at distances from 0.5 to 2.0 cm from the edge of plasma glow. Electrical conductivity measurements were performed between room temperature and 1000° C and then complimented with Raman spectroscopy and PL studies in an attempt to gain a better understanding of the CVD growth process and the resulting electrical and optical properties of the diamond films. Room temperature electrical conductivity was found to vary by over 5 orders of magnitude with increasing growth distance from the plasma, while only moderate changes were observed in the luminescence spectra.     

Open-Structured Materials: Skutterudites and Clathrates

There are a large number of inorganic compounds with open-framework structures that entrap atoms or molecules within the lattice. Of these, the skutterudites and type I clathrates have gained the greatest attention from the perspective of thermoelectric applications. The crystal structure of these materials can be considered as being open in the sense that they possess voids whereby interstitially placed atoms are bounded loosely, thereby creating localized disorder in an otherwise well-ordered, covalently bonded lattice. The optimum situation occurs if the intrinsic mobility is relatively high due to the well-ordered, periodic structure of the crystal framework while the phonons are scattered by localized disorder. Substantial experimental and theoretical research has been devoted to these two material systems over the past decade. This effort has shown that the physical properties are directly related to their unique crystal structures, as well as the different compositions that can be synthesized in order to modify these physical properties.     

七电极电导率传感器测量电路设计与实现

针对七电极电导率传感器的基本原理和特点进行了阐述,根据传感器本身物理特性以及高精度测量的要求,设计了能够满足低温漂、高精度、速度快的测量电路。采用D/A、A/D等集成电路芯片去实现对传感器的精确驱动和高速采样,相比于传统方式,驱动的频率和电压更加准确,并且容易更改,采用高速采样可以避免信号在调理过程中出现的失真。通过实验验证了电路的测量效果。     

Thermoelectric Properties of Co<Subscript>4</Subscript>Sb<Subscript>12</Subscript> Skutterudite Materials with Partial In Filling and Excess In Additions

The properties of Co₄Sb₁₂ with various In additions were studied. X-ray diffraction revealed the presence of the pure δ-phase of In_0.16Co₄Sb₁₂, whereas impurity phases (γ-CoSb₂ and InSb) appeared for x = 0.25, 0.40, 0.80, and 1.20. The homogeneity and morphology of the samples were observed by Seebeck microprobe and scanning electron microscopy, respectively. All the quenched ingots from which the studied samples were cut were inhomogeneous in the axial direction. The temperature dependence of the Seebeck coefficient (S), electrical conductivity (σ), and thermal conductivity (κ) was measured from room temperature up to 673 K. The Seebeck coefficient of all In-added Co₄Sb₁₂ materials was negative. When the filler concentration increases, the Seebeck coefficient decreases. The samples with In additions above the filling limit (x = 0.22) show an even lower Seebeck coefficient due to the formation of secondary phases: InSb and CoSb₂. The temperature variation of the electrical conductivity is semiconductor-like. The thermal conductivity of all the samples decreases with temperature. The central region of the In_0.4Co₄Sb₁₂ ingot shows the lowest thermal conductivity, probably due to the combined effect of (a) rattling due to maximum filling and (b) the presence of a small amount of fine-dispersed secondary phases at the grain boundaries. Thus, regardless of the non-single-phase morphology, a promising ZT (S ² σT/κ) value of 0.96 at 673 K has been obtained with an In addition above the filling limit.     

Ultrahigh Conductive Graphene Paper Based on Ball‐Milling Exfoliated Graphene

Due to low density, extremely high electrical and thermal conductivities, graphene has great potential to construct lightweight thermal conductive paper for high‐power electric devices. However, the remarkable properties of graphene are on a molecular level and difficult to achieve when processed into macroscopic paper. Here, an effective route to construct ultrahigh conductive graphene paper is developed. First, large‐volume, high‐concentration, plane‐defect‐free, few‐layer graphene dispersion is fast produced from graphite at high yield through ball milling. The exfoliated graphene dispersion is further processed into graphene paper through fast filtration, thermal treatment, and mechanical compression. The electrical and thermal conductivities of the resultant graphene paper are as high as 2231 S cm^?1 and 1529 W m^?1 K^?1, superior to previously reported graphene papers. Structural analyses confirm that the ultrahigh conductivities are attributed to high quality of graphene sheets, their compact ordered stacking, and large graphitic crystalline domain size, which improve electron and phonon transport within basal plane of graphene sheet and between graphene sheets.     

车载光伏供电控温系统的设计

该文以ARM9为主控芯片,以光伏电池供电,以半导体制冷片为降温装置,以小功率加热器为加热装置,并以DS18B20为温度传感器设计了一个节能环保的小型车载全天候控温系统。通过测试验证了该系统设计和控制策略的可行性,在一定程度上解决了户外泊车时车内的温度控制问题。