超长并列斜拉索尾流驰振及其控制风洞试验研究

通过气动弹性模型风洞试验,测试了不同风攻角及索间距下,并列超长拉索间的风致振动特性,研究了拉索尾流驰振的运动轨迹及其控制措施.研究表明,拉索发生尾流驰振时,其运动轨迹通常为椭圆轨道,振动主轴与来流方向成一定倾角;运动方向为靠近尾流外侧时,向下游运动,靠近尾流中心时,向上游运动;尾流驰振发生时,拉索从来流中吸收能量,振幅缓慢增大;随着风速增加,振幅增加较快直至出现明显的、振动主轴近似沿来流方向的极限环为止;采用分隔架可以有效抑制尾流驰振的发生,研究结果对并列拉索的抗风设计与振动控制具有指导意义.     

探空湿度传感器空间飞行姿态和加热模型研究

为计算出探空湿度传感器随气球上升过程中在空间的飞行姿态和测量周期,应用了一种计算流体动力学方法.首先,建立五种传感器间距模型,获得最优的传感器间距.其次,建立四种飞行姿态,通过观察传感器的壁面剪切应力大小,确定最优的飞行姿态角.最后,利用瞬态分析,仿真出0 ～32 km高空的加热时间和冷却时间,从而确定测量周期.仿真结果表明:在入口风速8 m/s,次流入口为10 m/s时,最优的间距为3.5 ～6 mm.传感器的俯仰角为45°时,壁面剪切应力较大,故较为理想的俯仰角为43°～48°.传感器的测量周期采用0.53 W的加热功率和温度降幅为超环境温度12℃所对应的时间.     

水平轴风力机串联工况尾流效应影响

为减小尾流效应对风力机输出功率的影响,基于CFX模拟实验研究8D串联间距风力机尾流场和不同方向速度场的变化规律.结果 表明,上游风力机的尾流叠加作用使下游风力机产生复杂的湍流和涡流现象,造成不同方向上速度差异.随着轴向距离增加,轴向速度先减小后增加,5D处轴向速度亏损最严重,而径向速度高速区在叶尖区迎风面,切向速度叶尖区影响最大.随着不同方向速度的恢复,8D截面处尾流影响基本消失.     

几何布局对掘进机位姿检测精度的影响分析

为实现综掘工作面悬臂式掘进机位姿无人化、高精度检测,提出了一种基于超宽带测距技术的掘进机位姿检测系统,推导了基于该系统的掘进机定位坐标及机身姿态角计算方法,通过Matlab仿真分析了基站布局间距、角度对定位精度的影响及机身定位点间距对姿态角检测精度的影响。仿真结果表明:随着基站至掘进机机身定位点的测量距离增大,系统定位精度降低;基站布局间距越大,系统定位精度越高;基站布局角度在yoz平面呈60°时系统定位精度优于基站布局角度呈0°及90°时;基站至掘进机机身定位点的测量距离对姿态角检测精度没有显著影响;机身定位点间距越小,系统姿态角检测精度越高。     

考虑速度对期望间距影响的车辆跟驰模型研究

为了真实地反映驾驶员在道路行驶中的车辆跟驰机理,使用相关性分析方法找出影响期望间距的关键因素,从而提出改进的基于期望间距的车辆跟驰模型(improved desired distance model,IDDM).利用NGSIM数据对IDDM和经典的Gipps车辆跟驰模型的参数进行了标定,之后对标定的模型进行评价.研究结果表明,前后两车的速度以及相对速度主要影响跟驰过程中驾驶员采用的期望间距;IDDM与传统Gipps模型相比,其加速度、速度与位置的仿真精度分别提高了0.24 m/s2、0.72 m/s、0.53 m,可以为车辆跟驰行为分析提供参考.     

66kV覆冰导线的舞动仿真分析

针对偏心覆冰导线在风的激励下极易诱发舞动对输电线路造成损坏,对整个供电系统的安全运行造成严重危害的问题,采用Fluent软件中的SSTk-ω模型对覆冰导线的空气动力参数进行了仿真,得到了各攻角下不同冰厚的升力、阻力系数以及邓哈托系数,并依据此结果判定覆冰导线是否发生舞动。仿真结果表明:在风速相同的情况下,覆冰厚度大的易发生驰振,在冰厚度相同的情况下,风速变大气动力系数变得平稳,不易发生驰振;6mm以下的覆冰导线不会发生驰振。仿真验证了覆冰导线模型的有效性,其数据结果对覆冰导线防舞工具的设计和安装都具有重要的参考价值。     

漂浮式斜拉桥全局模态对CFRP索的敏感性研究

斜拉桥复杂动力学问题中的一个关键问题是局部模态频率与全局模态频率成倍数匹配关系时可能导致的斜拉索大幅振动.本文针对这个问题,基于传递矩阵法,研究CFRP索对斜拉桥全局模态频率的敏感性.将斜拉桥的桥面梁和桥塔分别视为多离散弹性支承欧拉伯努利梁,建立其动力学控制微分方程,基于传递矩阵法对其特征频率进行求解.以长沙某独塔斜拉桥作为算例,对结构主要构件:斜拉索、塔和桥面梁的刚度变化对全局模态频率变化的敏感性问题进行了分析.结果表明,桥面梁和桥塔全局模态频率对斜拉索刚度变化非常敏感,并且用CFRP索替换钢质拉索可能避开拉索局部模态与斜拉桥全局模态的倍频关系,从而控制斜拉索的大幅振动.     

BRDF模型观测角测量模块的研制

BRDF(双向反射分布函数)模型是多角度遥感定量解译的理论基础,观测角是模型中的重要参数,其中包括观测天顶角和观测方向角.传统的测量观测角的方法是采用机械圆盘以及在地表画圆,但这种测量方法设备笨重、精度低、效率低,不适合水域的测量.提出了一种新的电子测量方法,利用加速度计测量重力加速度的三维分量,利用磁阻传感器测量地磁场的三维分量,通过坐标投影原理得到BRDF模型中的观测角.这种测量方法设备便携、成本低、效率高.观测天顶角的测量范围为-90°～90°,观测方位角的测量范围为0°～ 360°,在测量范围内的测量精度为±1°,满足BRDF观测角的测量要求.     

舰船热尾流的测试技术研究

舰艇螺旋桨的扰动和船体引起的船壳涡等将破坏尾流区中原有的温度梯度结构,形成明显的冷的或热的温度变化,称为热尾流.本文介绍了舰船热尾流的主要特征,研制了舰船热尾流和电导尾流实验测量系统,在海上试验测量了水面舰艇热尾流和电导尾流信号.研究结果表明舰艇存在明显的温度和电导信号,海洋表层温度梯度越大,热尾流信号就越强;目标船的吨位和吃水深度越大,热尾流的信号也越强.利用高灵敏度和高分辨率的温度和电导率传感器能可靠的将舰艇热尾流识别出来,有希望作为鱼雷攻击舰艇的一种新的尾流自导手段.     

大位移传感器的设计与验证

为了研发与验证Flex无线传感器用于土体监测时的可行性,本文参考已有的土体变形监测技术后,结合3D打印技术,传感测量技术与蓝牙无线传输技术,成功制作了 Flex无线土体位移传感器.本试验首先通过3D打印封装Flex制作变形监测传感器,再由室内试验模拟基坑和边坡工况,利用Flex传感器随着土体的变形分别可以对土体水平或竖直位移进行测 量.试验结果表明:Flex在用作室内试验时有较好的精确度,单个传感器量程为0°～60°,分辨率为0.3°～0.4°,并且可以实时反映土体的变化情况,其回传到后台的数据可以进一步分析得到土体位移量.     

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     

煤矿井下安全监控分站的设计及其仿真实现

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.     

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。