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一种基于相位差测量的WSN节点测距方法 总被引:1,自引:0,他引:1
提出了一种基于相位差测量的WSN节点测距方法.该方法任取WSN网络中的两个节点作为发射节点,并使它们以非常接近的高频发射未调制的正弦波以便在空间叠加产生干涉信号,根据网络中不同接收节点测量的其低频RSSI信号的相位值的差值可以得到发射节点和接收节点之间的距离关系并由此最终得出节点间的距离.其特点是有较高的测距精度,可用于WSN节点的2D与3D定位,却无需额外的高精度硬件,适合于低成本的WSN网络应用.实际试验验证了该方法的有效性. 相似文献
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针对传统相位差法超声流量计在相位测量中易受外界干扰、准确度低的问题,提出了一种基于全相位快速傅立叶变换算法的超声波流量计相位检测方法。该方法由PLL时钟发生器产生两个频率相近的正弦信号分别用于激励与混频,并通过差频技术将混频后的参考信号与回波目标信号的相位信息从高频处理为低频信号,再由16位ADC对信号同步采样。超声波采样信号通过全相位预处理后进行FFT计算,得到准确的相位结果。同时,对比分析了全相位FFT的抗干扰性和采样频率对相位测量精度的影响,并将设计的电路应用于超声波液体流量测量,最终实验结果表明超声波流量计样机的测量误差优于1%,测量量程比为160:1。 相似文献
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因为作用距离较短,所以超声波传感器一般用于机器人低速运行在静态环境中进行的短距离测量,无法作为高速行驶陆地自主车的前视传感器来使用.为解决问题,根据超声换能器功率高、频率低时,发射的超声波衰减慢、传播距离远的原理,基于能改善传统压电换能器和磁致伸缩换能器的声匹配、提高气介式超声换能器辐射声功率及效率的弯曲振动换能器,研制了一种高功率、低频率、作用距离远的超声传感器,其波束角为9°,最大作用距离可超过35m,经实验测定,超声传感器在最大量程处测量数据稳定、指向性强,完全能够满足在高速行驶的陆地自主车进行远距离测距的要求. 相似文献
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张涛 《计算机测量与控制》2015,23(1):86-89
为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值. 相似文献
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Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China. 相似文献
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In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times. 相似文献
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《Information & Management》2016,53(6):787-802
Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice. 相似文献
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Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs. 相似文献
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Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel. 相似文献
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《浙江大学学报:C卷英文版》2014,(11)
正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and 相似文献
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Zhao-hui WU 《浙江大学学报:C卷英文版》2014,(10)
正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control 相似文献
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《浙江大学学报:C卷英文版》2014,(10)
正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate 相似文献