共查询到20条相似文献,搜索用时 78 毫秒
2.
3.
提高超声波测距性能是超声波测距技术研究的关键点;不同的超声波接收信号检测和处理技术会涉及到不同的硬件结构、软件实现复杂度,导致超声波测距性能差异,进而影响整个系统的定位性能;为提高定位系统的定位精度,针对特定的六元超声波阵列测距系统进行超声波阵列测距实验,对可能造成测距误差的误差源进行分析,并分别采用温度补偿法和最小二乘回归法对测量数据进行校正;实验结果表明,设计的网络节点测量距离能够达到15 m,且最小二乘校正模型的测量结果有效地减小了测距误差,提高了测距精度。 相似文献
4.
超声波测量技术具有速度快、成本低、测量范围广等优点,广泛应用于多种工业领域。为满足工业中对温度测量的需求,本文提出了超声波温度测量系统。本系统基于超声波的传播速度与环境温度的关系,以STC12单片机作为系统硬件电路控制核心,采用幅度和相位调制的矩形波作为发射波,实现在恒温箱空气介质中固定距离下的超声波飞行时间的测量,以此确定介质的平均温度。测量数据由单片机传输到上位机进行处理和显示,并与恒温箱热电偶测得的温度对照,验证实验结果。实验结果证明本系统可以准确测量温度,温度范围约在35℃—90℃。 相似文献
5.
6.
为了提高超声波测距精度,构建了基于AVR单片机的测距及数据处理系统。分析了超声波测距的原理,以AVR单片机为处理器设计了超声波产生和发射电路、超声波接收和信号处理电路以及温度测量和补偿电路等。针对温度对超声波速度的影响,根据超声波速度与温度的关系,设计了超声波速度补偿算法。为了提高回波时间测量准确性,减小随机噪声及空气中其他杂散播干扰的影响,采用均值数字滤波方法,对计数时间进行处理。实测结果表明,在3cm~400cm范围内,超声波测距系统测量数据准确,最大误差为0.66cm。 相似文献
7.
8.
9.
10.
介绍了超声时延法测距的基本原理,设计并实现了一种基于DSP的超声液位计系统,改进国内同类产品精度和稳定度偏低的问题。利用选用的AD、DSP芯片特点,给出了一种简单高效率的超声换能器驱动电路和回波采集放大电路的实现方案;使用通用16位定点DSP芯片TMS320VC5502,实现测距算法,增强了后端数字信号处理能力;使用收发一体窄带超声换能器发射和接收超声信号,其中心频率20kHz,3dB带宽1kHz。实验结果表明,本系统测量范围为0.5~18m,测量精度可达到测量距离的0.5%。 相似文献
11.
SUN PingPing LIU DeAn ZHANG YanLi LI XiaoYan ZHANG Yan & ZHU JianQiang National Laboratory on High Power Laser Physics 《中国科学:物理学 力学 天文学(英文版)》2011,(3)
The theoretical model of spatial noise passing through a spatial filter is established in high power laser system under the small signal approximation. The transmission characteristic for a noise signal passing through spatial filters with different magnifications is analyzed by numerical simulation, according to the actual structure of the high power laser system. The results show that the spatial modulation period of low-frequency noise getting through the pinhole will be proportional to the magnification... 相似文献
12.
针对双稳系统的高频信号响应,探讨了双稳调参的高频共振机理.研究表明,二次采样频率变换并不改变双稳结构直接在原系统结构上在与高频映射对应的低频处实现共振,而双稳系统参数调节是调参改变双稳结构并直接在高频处实现共振.双稳系统参数调节之所以能够实现高频随机共振,是因为同时调节双稳系统两参数可使Kramers逃逸速率不存在极限值,突破了随机共振信号频率必须在小频率范围内的限制.
关键词:
双稳系统
高频共振
二次采样频率变换
系统参数调节 相似文献
13.
14.
同时记录与高速事件相关的信息是进行胶片判读处理的必要条件,数据记录系统就是由高速摄影机的同步控制信号控制选通,将与事件相关的信息经特殊处理,由集成数据点阵头记录在胶片上,为此后的胶片判读及对拍摄事件进行更精细的分析处理提供定量、实时的依据。 相似文献
15.
电力系统是一个由多个子系统构成的综合性系统,作为一个能够实现海量数据处理同时具有高实时性、高可靠性的管理控制平台,需要电力系统能够实现对所辖多个子系统进行复杂、细密、大范围的访问控制,这些条件要求能够设计出合理有效的访问控制模型。为了实现安全、可靠、高效的电力系统访问控制提出了将传统电力系统同云存储平台相结合的访问控制方案,通过云存储平台对数据进行存取可以达到大数据量、均衡负载、安全可靠的目的;通过添加可信度因子构建访问控制模型,根据不同用户的可行度计算值分配给以不同的权限,匹配其可操作的资源,实现了对于用户操作对象的细化识别。 相似文献
16.
Electrohydrodynamic (EHD) atomization consists in using an electric field for spraying a liquid flowing through a capillary. The applications are: mass spectrometry, colloid thrusters and more recently medicine nebulization processes. EHD atomization provides the ability to control the generated droplets size by adjusting electrospray parameters. It is however essential to manufacture the emitters into arrays because flow through a stable cone-jet mode electrospray can only be maintained at low flow rate and most applications require a high throughput. We propose a new design of a multiple electrospray system involving an innovative nozzle shape and flow restrictor system. Nozzles and microfluidic restrictor system are manufactured on the same polycarbonate sheet using the excimer laser technology and thus allowing a high compactness of this system. 相似文献
17.
《Superlattices and Microstructures》1999,25(1-2):227-233
The electron transport through a quantum-wire system in the presence of inhomogeneous magnetic fields is investigated theoretically. The system consists of two parallel quantum wires coupled by two ballistic windows, while the magnetic fields applied are uniform and equal in the two wires but vanishing in the two coupling windows and everywhere between the wires. Various transmissions of the system are calculated. It is found that the inhomogeneous magnetic fields induce irregular transmission oscillations in the low and moderate magnetic-field regions, and regular ones in the high field region. These transmission oscillations are due to interference between the electron waves traveling through different coupling windows and can be interpreted in terms of a semiclassical model. The Hall resistance of the system is also calculated and is found to show similar regular oscillations at high magnetic fields. 相似文献
18.
19.
基于激光外差技术的高分辨率整层大气透过率测量 总被引:1,自引:0,他引:1
激光外差技术是一种高灵敏度的光谱探测技术,利用该技术研制的装置易于集成化小型化,可以进行地基或星载的地球大气或天文观测。基于激光外差光谱测量技术,结合自研的太阳跟踪仪建立了一套高分辨率整层大气透过率测量系统,系统分辨率约为0.006 cm-1。该系统利用太阳光和红外激光在非线性探测器中进行光学混频,通过对获取的混频信号进行电子学滤波和平方率探测,获得了高光谱分辨率的外差信号。采用Langley-plot定标法对测量系统进行定标,获取了仪器标定常数和对应的大气总光学厚度,实现了中红外波段整层大气透过率的实时测量。同时,将实测整层大气透过率与MODTRAN5.0软件仿真计算的结果进行对比分析,两者的一致性较好。分析表明该测量系统具有很高的分辨率并且性能稳定可靠,在大气科学、天文观测和激光大气传输等研究领域具有广阔的应用前景。 相似文献
20.
Semi-active vibration control systems are becoming popular because they offer both the reliability of passive systems and the versatility of active control without high power demands. In this work, a new semi-active control system is proposed and studied numerically. The system consists of variable-friction dampers linked to the structure through cables. Auxiliary soft springs in parallel with these friction dampers allow them to return to their initial pre-tensioned state. Using cables makes the system suitable for deployable, flexible and lightweight structures, such as space structures (spacecraft). A control system with three control laws applied to a single-degree-of-freedom structure is studied. Two of these laws are derived by using Lyapunov theory, whereas the third one is developed heuristically. In order to assess the performance of the control system, a parametric study is carried out through numerical simulations. An application of the proposed method to multi-degree-of-freedom structures is also presented and demonstrated through a numerical example. The system in semi-active mode is more effective than in passive mode and its effectiveness is less sensitive to loss of pre-tension. 相似文献