基于差压法的一种新型液体流量传感器

设计了一种新型液体流量传感器,并对其进行了制作和实验标定.这种流量传感器主要由特制的导流管和现有压力传感器组成.其基本原理是输入口与输出口这间的压力差与通过导液管的流速直接相关.用压力传感器测量导液管入口与出口之间的压力差,并将其转换成电压量输出.通过检测导液管两端的压力差,即可计算出通过导游管的流速和流量.这种流量传感器主要有结构简单、灵敏度高、精确度高、量程范围宽、成本低等优点.     

系留气球差压数据的三余度设计

开展系留气球差压数据的余度设计可有效提高压力调节系统工作可靠性,如何减少差压传感器配置的同时提高差压数据的可靠性是关键;通过改变传统上差压传感器只是测量气室与外界大气两个压力差值的使用模式,利用差压传感器测量相邻两个气室之间的压力差值,采用硬件双余度差压传感器的配置实现了系留气球气囊差压数据的三余度设计,给出了基于互比监控的故障判定逻辑和故障处置方法;试验结果表明:该设计显著提高了压力调节系统工作可靠性,仅需要加倍差压传感器配置,就可获得差压数据的三余度能力,以较低的硬件成本大幅提高了系留气球差压数据测量的容错能力.     

基于文丘里流量传感器的湿气两相流量模型研究

研究旨在通过计算流体动力学(CFD)仿真技术预测的湿气气、液两相流量.以双差压长喉颈文丘里流量传感器为测量手段.模拟压力范围0.4,0.6,0.8,1.0,1.2 MPa,气相体积流量范围为140～283 m3/h,温度范围23 ～30℃,含液率范围0.5％～1.5％.文丘里流量传感器口径为DN100,节流比为0.55.多相流模型采用离散相模型(DPM),利用欧拉壁面(EWF)模型以模拟管壁上的薄液膜.分析得出压力、气相流速和液相体积含率(LVF)对液膜厚度的影响规律.根据仿真结果建立基于双差压比值法的气、液两相流量预测模型.将仿真值与实验值进行比较,气相流量模型预测的均方根误差为1.8％,且液相流量模型预测的均方根误差为6.1％.     

基于AD7745的电容差压传感器设计

以低功耗微处理器MSP430为核心,采用新型的模数转换芯片AD7745,设计了一种测量液体差压的电容式差压传感器.给出了电容式差压传感器的设计原理和AD7745与MSP430软硬件设计.实验结果表明:该传感器在量程为+100pF时,测量值稳定在高16位,分辨率为0.0001pF.电容传感器具有较好的线性输出特性和很好的...     

差分式层流流量传感技术研究

层流流量计非常适合于纯净气体微小流量测量,但是常规层流流量测量方法为了保证较好的流量－差压线性关系,其毛细管需要很长,导致层流流量计存在压损大的问题,提出一种差分式层流流量传感技术,该技术中层流流量传感器包括两段长度不同的毛细管组。工作时,分别测量两段毛细管组两端的差压,并取两个差压之差,即差压差分值,用于流量计算。通过差压差分,毛细管进出口局部损失和层流起始段流动损失等非线性压降被抵消掉,差压差分值与流量之间具有理想的线性关系,介绍了差分式层流流量传感技术原理,分析了传感元件中沿流道的压降特性,设计了模型传感器并进行了实验测试。实验结果表明,在(0.016~ 2.500)m3/h的流量测试范围内,差分式层流流量传感器流量测量误差在±１％以内,证明了这一新型层流流量传感方法的正确性。?     

用于过程控制的浮点数快速开平方程序

<正> 一、概述在用微机组成的生产过程控制系统中,流体(如液体、汽、风量等)的流量是主要的被控参数之一。而流经孔板的差压信号与流量之间的关系是非线性的,因而其标度变换也属于非线性的。常用的数学模型为:G=KΔP~(1/2)其中,G——流体的流量;K——标度系数;△P——节流装置的差压。由上式可知,流体的流量与被测流体流经节流装置前后的压力差的平方根成正比。在定点计算中,将一个数开平方常用减奇法,其     

基于内压式点滴速度传感器的设计

点滴法在液体微流量检测与控制方面的应用普遍,液体微流量的检测一直是研究的难点.利用医用输液管储液瓶、压力传感器和仪表放大器设计一种点滴速度检测传感器,用压力传感器检测储液瓶内的压力并转换为电压输出,通过测量电压后换算为点滴速度.设计并制作了传感器硬件,并进行实验测试,获得传感器点滴速度关系表达式.     

基于铁磁性液体的微差压传感器研究

差压是一种重要的力学参数,为了提高差压的测量精度,应用新型纳米材料--磁性液体设计了一种微差压传感器,建立了传感器的理论模型并对其输入输出关系进行了理论推导.该传感器采用螺线管式差动变压器的工作原理,其核心部分是可变互感,利用磁性液体兼具磁性和流动性的特点实现微差压的测量.实验表明,该种磁性液体微差压传感器具有工作压力范围大、线性度好、灵敏度高、稳定可靠等优点,可以广泛应用于工业过程控制、机械制造、生物医学工程等许多领域.     

基于单片机控制的毛细管流量特性研究

毛细管是一种使用广泛的节流装置,由于毛细管管内液体层流与非层流运动的存在,使得其流量计算较为复杂.针对液体经过毛细管的流体特性,设计出了一套毛细管流量差压控制系统,该系统以单片机作为控制器,通过控制微型气泵为毛细管两端提供恒定压强差,并由压力传感器进行毛细管两端压强检测,探索出了毛细管差压流量特性,为不同条件下毛细管的选取提供了实验方法.     

差压变送器的应用和故障分析

在工业自动化生产中，差压变送器已得到了非常广泛的应用，其在自动控制系统中也发挥着日益重要的作用。本文主要介绍差压变送器的工作原理，常用的三种测量应用方式，主要安装方法及注意事项，使用调查法、直观法、检测法诊断差压变送器测量回路的应用故障，并重点对导压管堵塞、泄漏、平衡泄漏、气体流量测量导压管积液等问题引起的故障现象进行了重点分析。     

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.