基于文丘里的湿气流量测量实验研究

对可应用于民用湿天然气流量测量的小口径文丘里管进行了实验研究。通过一台气流式雾化器用氮气把水雾化成湿气,再通过一台入口直径6mm,直径比0.567的文丘里管进行在线流量测量,获得了一定工况参数范围内不同压力、气体密度弗鲁德系数和洛克哈特-马蒂内利参数下的湿气虚高特性数据。分析了洛克哈特-马蒂内利参数、气液密度比、气体密度弗鲁德系数、韦伯数和液气体积比对湿气虚高修正系数的影响。调研了基于差压流量计的7种虚高指数修正关系式,并根据实验数据改进了R-H关系式。提出了针对小口径文丘里测量湿气的气相流量计算模型。实验结果表明,在压力0.5~2.0 MPa,气体密度弗鲁德系数1.0~8.5,洛克哈特-马蒂内利参数0~0.34, 气相体积比95%~100%范围内,该模型修正的气相流量相对误差小于士2.1%,气相均方根误差为1.2%,优于其他模型的修正结果。     

双向内外管差压流量计参数优化与数值模拟

在调研了国内外差压流量计研究现状的基础上,针对内外管差压流量计的测量特点与存在的问题,设计了双向内外管差压流量计。创新性地将二次正交回归组合方法与计算流体力学技术相结合。根据Fluent软件的流场仿真结果,对双向内外管差压流量计进行结构优化,以获得在最大压损比指标下的结构参数。在流速为1 m/s与3 m/s的条件下,利用二次回归方程得到的优化结果为:节流件大径11.15 mm,小径4.45 mm。然后,对双向内外管差压流量计和内外管差压流量计进行对比。Fluent软件的分析结果表明:双向内外管差压流量计具有更大的压损比,即内外压差信号更大,而前后压差(即永久压损)信号更小。永久压损的减少,可带动传输动能损失的下降,则相应的动力费用降低、经济效益提高。双向内外管差压流量计可盲插安装,综合性能更好,实用性更强,可以在化工与石油领域中进一步推广。     

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％.     

凝析天然气流量测量新方法

基于多个差压波动信号,提出了一种凝析天然气流量测量新方法。该方法在实际测量过程中,首先对当前流型进行辨识;然后应用与流型对应的流量测量模型对已辨识的流型进行流量计算。流量测量模型中的差压值由节流式流量计提供的多个差压波动信号中分离得出,分离矩阵的各矩阵元素由差压波动信号的统计特征值求得。实验结果表明,凝析天然气流量测量新方法是有效的,其测量精度满足工业应用的要求。     

差压式涡街质量流量计信号处理系统的研制

差压式涡街质量流量计是一种新型的质量流量测量装置,通过测量旋涡发生体上下游管壁处的差压,同时获取涡街频率信号和压力损失信号.为了将差压中这两路信号分离并准确测量其值,研制了采用程控放大、自适应滤波技术及FFT算法的信号处理系统.实验结果表明,该信号处理系统能够准确地从差压式涡街质量流量计输出信号中测得管内流体的质量流量值,同时改善了装置的抗干扰能力和通用性,提高了涡街频率测量的准确度,并且具有结构简单、成本低、适用性广等优点.     

新型差压流量计的结构与性能研究

尽管流量计种类多样,但由于被测流体的复杂性、要求的多样性和使用条件的特殊性,直到现在仍有很多流量测量任务未能达得到满意的效果。因此,开发新型的流量计或改进现有的产品仍势在必行。介绍了四种新型差压流量计。其中,双量程差压流量计采用增设低量程差压变送器的方法,提升量程低端的差压测量准确度,从而提高量程低端流量测量准确度、扩大量程比。双向孔板流量计采用孔板不削斜角等方法,实现双向流量测量。湿气体流量计采用偏心孔板和弃用针形阀三阀组等方法,消除积液带来的误差。耐腐蚀弯管流量计采用新型氟塑料喷涂的方法,提高耐腐蚀能力,并用吹气和弯管管外伴热保温的方法防止介质的结晶和自聚,从而增强系统的可靠性和延长使用寿命。     

流量仪表应用和发展若干动态

回顾了前一时期差压式、电磁式、科里奥利质量式、热式、间接法质量式流量计的应用和发展概况。阐述了弯管流量计、椭圆节流流量计、内锥体流量计、具有自诊断功能的电磁流量计、宽范围度非满管电磁流量计、压缩天然气汽车加气机用科里奥利流量计、能测气液混合流体的科里奥利流量计、微机电系统热式流量计等的若干情况。在新测量原理流量仪表方面，概述了声纳流量计和微波气同双相流量计，以及利用蝶阀瓣产生差压的蝶流量控制阀和用电磁流量计在线测量液体粘度。     

新型智能差压式流量计的设计

通过对管内流体流动机理的分析,推导出差压式流量计的流量方程,并提出一种有别于目前普遍采用的新型智能差压流量计的设计方法,同时分析了误差的形成并给出误差修正。用水流标准装置对流量计进行了实流校验,进行了不确定度分析与计算,确定了流量计的准确度等级,从而证明了所设计系统的可行性。     

阿牛巴管流量计及其在蒸汽流量中的应用

工概述由于带有压力补偿和二次显示仪表的阿牛巴管流量计只适用于温度＜250℃,压力＄2．SMFa的炮和蒸汽的测量,而当蒸汽温度＞2刀℃,压力＞2．SMpe时其性能指标就会发生变化,影响测量精度。不带压力补偿及二次显示仪表的阿牛巴管流量计则可适用于温度sgn℃,压力S6．4Mpe的过热蒸气中。该流量计是一种新型的差压式流量计,又称笛形均速管,具有结构新颖,安装维修方便、节约能源、测量范围宽、测量精度高,在1：10的流量范围内不作流星系数K的修正也能保证】1％的精度误差,而且流速越高,K值越稳定,误差也越小。它仅是插入到管径…     

靶式流量计的分类及应用

靶式流量计是常用的流量测量仪表.为便于制造商和用户之间的交流,促进其更快、更有序的发展,具体介绍了靶式流量计的测量原理,提出分类依据和分类命名.根据结构不同,此类流量计分为轴封膜片式、挠性管式、扭力管式和差压式;根据力转换方式不同,分为力一气压转换型、力一电压转换型和力一差压转换型.详细描述了各种类型的结构,提出差压靶的新理论,分析了传统干校法的不足,设计了一种新干校法装置,并呼吁尽快制定靶式流量计的国家标准.     

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.