基于MSP430F1611的Zigbee超声波液位传感器的设计

ZigBee是一种新型的低功率、低成本、近距离的无线通信技术,是实现无线传感器网络的理想解决方案。本文介绍了一种基于ZigBee协议的无线超声波传感器设计方案。该液位传感器以CC2420射频芯片为无线传感器网络接口实现数据的收发,采用低功耗微处理器MSP430F1611为控制核心。     

基于超声波传感技术的群罐液位监控系统的设计

本文利用超声波传感技术结合相应测试算法对群罐体容器内液位进行测控和集中管理，可实现非接触式测量，大大增加了系统的连续工作时间，简化和方便了对传感器的维护，还可实现不停产检修，提高了生产率和管理水平。本文简述了该系统的工作原理、组成结构和设计方法，并对传感器及微控制器的选用等内容进行了论述。采用单片机来控制超声波的发射与接收。并且计算出液位，使测试仪器具有更高的智能性。     

一种基于超声阻抗和回波能量的液位检测方法

针对超声波液位检测方法中,传感器和容器壁间的耦合度不佳所带来的稳定性和可靠性降低的问题,提出了一种基于阻抗法并利用回波能量来实现液位检测的方法.该方法利用液位上下方气液介质的阻抗不相等的特性,计算和比较两个接收传感器所接收到的回波能量之间的差异,以此来确定液位的位置.实验结果表明,该方法能够有效地克服因耦合条件不佳所带来的问题,检测精度满足应用需求.     

基于单片机的酒罐液位测试系统研制

针对目前酒罐液位仪稳定性和安全性差、精度低、安装困难等问题,研制了以单片机为控制器、轮辐式称重传感器测液位、数码显示等功能为一体的酒罐液位测试系统。分析了超声波传感器和压力传感器在酒罐液位仪中测量的缺陷,提出了以三称重传感器串联方式测量酒罐液位,改善了系统的可靠性和准确度。该系统能实时数码显示,并可与上位机通讯。     

超声波避撞预警系统的研究

本文介绍一种用于汽车倒车避撞的超声波无线距离测量系统。系统由下位机与上位机两部分组成,下位机主要由超声波发射电路、超声波接收电路、无线收发模块及单片机组成,上位机由单片机、无线收发模块、显示电路等组成,下位机与上位机之间通过无线收发模块传输信息。文中分析了超声波测距电路的设计方法,叙述了采用无线通信技术实现数据远程传输的设计思路。该系统测量距离方便、灵活、稳定。     

基于电容传感器的高精度液位检测装置设计

设计了一种使用电容传感器的液位检测装置。检测装置采用TI的电容传感器FDC2214进行多通道电容检测,检测出的电容数字量经I2C总线送下位机换算出当前液位高度后发送至上位机LabVIEW显示。该装置采用容器与电容极板相分离的非接触测量设计,能快速便捷地检测不同液体的液位。实验结果表明,该装置应用场合广泛,能测量0～100 mm液位高度,测量相对误差为4%,为非接触测量液位提供了参考方案。     

基于nRF2401无线收发模块和超声波技术的精确定位系统的研制

精确的位置信息是实现普适计算的要求。提出了基于nRF2401无线收发模块和超声波技术的精确定位系统的组成框架和定位算法;并给出了基于nRF2401无线收发模块组成传感器网络的MAC协议和超声波收发时间差的修正方案。     

基于W77E58的无线液位测量系统

基于W77E58的无线液位测量系统由超声波传感器、单片机W77E58和无线数据传输模块STR-15组成。传感器将接收到的信号经数据处理后由无线数据传输模块送入上位机进行显示、超限报警和数据存储。文章介绍了该系统各组成部分的硬件和软件设计。     

无线超声波液位测量系统的设计

针对传统的液位测量仪表大多不具备无线通信功能、在复杂环境中不易布线的问题,提出了一种具有GPRS通信功能的无线超声波液位测量系统的设计方案。该系统采用LM3S811作为主控器件,将超声波液位测量电路采集的数据通过GPRS通信模块传输至监控中心的服务器端;服务器端采用JSP技术进行动态网页开发,其后台通过访问SQL Server数据库存储信息。测试结果验证了该系统的可行性。     

压力对西门子超声波液位计测量精度的影响

超声波液位计因其测量精度高、成本低的特点,在项目应用上常被用于常温常压容器内的连续液位值检测,特别是在敞口容器和水渠上应用广泛。由于其探头的设计对测量压力有一定限制,因此对于密闭的、带微正压容器的液位检测设计通常选用其他形式的液位计,这大大限制了超声波液位计的使用范围。为了验证超声波液位计能在微正压的工艺条件下正常使用,对西门子LUT400系列超声波液位计在0～7.5 kPa环境下进行了试验。分别测试了当压力从升高到降低时超声波液位计的上行/下行测量误差,并将其和重复性数据进行比对分析。分析结果表明,超声波液位计至少在7.5 kPa工作环境下,其性能和测量精度满足产品本身的设计性能,为今后超声波液位计在密闭、微正压工艺条件下的使用提供了有力的选型依据,拓展了其使用的范围。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.