一个简单的非水平均匀的大气临边矢量辐射传输模式

临边或掩星探测是通过对大气的切片式观测方式所建立的反演方法,可以获取大气要素垂直分层的精细分布,是卫星遥感的一种重要方式和方向。目前已有的临边大气辐射传输模式大部分是基于水平均匀分布的一维模式,且以不包含大气偏振模拟的模式为主,而偏振是未来大气遥感的重要手段,特别是在紫外波段的临边探测。为满足我国下一代临边探测的需求,编写了一个基于逐次散射法的临边矢量辐射传输模式,该模式可实现对临边辐射的4个Stokes参数的模拟,并考虑了大气水平非均匀分布的影响。在环境参数完全相同条件下,将标量计算方式下辐射强度的模拟结果与郭霞等的LGLTRAN模式的模拟结果进行比较,结果验证了模式的合理性。在此基础上对不同大气分层条件下的临边Stokes矢量进行了模拟和简单的分析。     

可程控遥感数据动态采集下临空高速目标探测系统设计

为实现对临空高速目标数据的跨域存储与调度,解决与目标节点探测相关的实际应用问题,设计可程控遥感数据动态采集下的临空高速目标探测系统;同时连接物理设备层、数据聚化层与应用接口层,完成可程控遥感数据动态采集下的目标探测系统应用框架搭建;利用MongoDB数据库架构与MysQL数据库表,建立必要的目标数据存储模型,实现临空高速目标数据存储模块的指向性连接;计算最大探测距离实值,根据目标探测参数的设计原理,定义与脉冲函数相关的应用表达式,实现对待探测临空高速目标信号源的分析与处理,完成可程控遥感数据动态采集下临空高速目标探测系统设计;实验结果表明,可程控遥感探测系统中已存储目标数据的跨域调度速率可达10.0×10⁷ T/s,单位时间内的最小信息存储值也接近4.2×10⁷ T,可在解决相关节点探测应用问题的同时,实现对临空高速目标数据的合理化存储与调度。     

一种GPS探空仪风失量反演算法

给出了采用矢量滑窗平均来反演GPS探空仪风矢量的算法。采用此算法对探空数据进行处理,可以明显减少大气波动的影响,得到以矢量形式表征的测风数据。通过和业内公认的标准探测设备Vaisala GPS探空仪的测风数据比较,表明此算法在实际应用中的可行性和优越性。     

8毫米云雷达与探空观测确定云底和云顶高度的对比分析

利用地基Ka波段云雷达和无线电探空仪数据进行云边界识别和对比分析研究。结果表明,8毫米波云雷达探测的云底高度比无线电探空仪观测偏低约300m,大多数情况下二者识别的云底高度接近;而判定的云顶高度偏差较大。雷达与探空云底高度判别偏差较大时,在云下常存在大气"干层",此时雷达探测更为灵敏;探空仪水平漂移及其湿度传感器的探测误差随高度增加是造成两者偏差的主要原因。通过计算和对比雷达反射率的时空变化率,给出了云雷达确定云底和云顶高度的一个可信度判据。     

基于某低空飞艇压力高度及载荷能力的研究

由于大气压力、温度随着海拔高度的变化而变化.在飞艇升降过程中,艇囊中的浮升气体(氦气)随着外界大气压力、温度的变化产生压缩或膨胀,使飞艇净静升力发生变化,从而影响了飞艇的载荷能力和能够达到的海拔高度.为了在标准大气(International Standard Atmosphere)和非标准大气(Off-Standard Atmosphere)条件下,研究了飞艇压力高度随充氦体积变化规律和载荷能力随高度变化的规律,给出了充氦体积占飞艇总气囊体积比例、压力高度、净静升力和有效载荷之间的变化关系,并结合某低空试验飞艇进行了仿真计算和分析,为飞艇的总体设计和实际使用提供了理论基础.     

飞艇扰动特性的分析方法研究

目前,研究大气扰动对飞艇的影响,广泛使用简化大气扰动模型,又称工程化模型.以大气紊流为特例,分析了其对飞艇性能的影响.首先,给出了大气紊流的基本情况,包括其频谱特性、扰动特性、尺度和强度,给出了其仿真模型.并给出风场干扰飞艇的模型情况,分别在线性化和非线性化模型上加入大气紊流,进行仿真分析.通过仿真结果,研究了其对飞艇...     

大气紊流影响下飞艇水平面内运动分析

大气扰动是影响高空飞艇水平面内运动的重要原因.研究紊流风速对飞艇飞行性能的影响时,大都采用Taylor冻结场假设,但这样建立的紊流风场模型,不适用于飞艇这类低动态飞行器,需要考虑时间变化对紊流风速的影响.首先给出大气紊流的一般性描述,包括相关函数、频谱函数、尺度和强度的选取,然后建立含扰动风参数的水平面内飞艇动力学仿真模型.最后分别将不考虑时间变化的扰动风和考虑时间变化的扰动风加到飞艇动力学模型上,进行仿真分析.仿真结果表明,考虑时间变化后的紊流风速模型能真实反映飞艇对大气紊流响应的随机特性.     

183.31 GHz二单元干涉仪实验研究

干涉综合孔径技术的应用使得辐射计有效解决了实孔径分辨率低、星载天线机械扫描技术困难等一系列问题。183.31 GHz干涉式综合孔径辐射计对于大气水汽的垂直分布探测、强降雨探测以及云中液态含水量探测等具有重要作用,为数值天气预报提供重要参数。以验证183.31 GHz全尺度样机原理功能为目的,研制了183.31 GHz二单元干涉仪,并给出了功能性测试结果。     

平流层验证飞艇横侧向模型辨识研究

研究采用系统辨识方法建立平流层验证飞艇横侧向模型,针对飞行试验中风的扰动和测量噪声明显,对辨识参数的精度有影响。为解决上述问题,提出了采用滤波误差法,辨识稳定微分和控制微分系数的策略,获得飞艇较精确的平飞横侧向模型。首先考虑飞艇为浮力体,质量和惯量受环境影响较大,很难精确测量的问题,将飞艇非线性模型转化为具有稳定性微分和控制微分的飞艇横侧向线性模型,辨识参数不受质量、惯量变化的影响,并采用滤波误差方法,辨识模型的稳定微分和控制微分,可以减小风的扰动误差对辨识精度的影响,最后用辨识模型进行飞行仿真,将仿真得到的数据和实际飞行试验数据进行对比分析,结果表明,辨识得到的模型可以较好地反映飞艇的动力学特性,可为飞艇偏航控制器的设计提供参考。     

利用合成孔径雷达研究中尺度雷暴的细结构

雷暴结构的探测是当今的热点问题。雷暴底层的细结构探测尚未见报道。本文利用一幅ERS-1图像,探测雷暴底层在海面留下的痕迹,结合辅助NOAA AVHRR和NCEP数据分析了2002年8月11日发生在台湾海峡的一次中尺度雷暴过程。结果表明,此次雷暴过程是在锋面前沿产生的,北风和南风切变为此次过程提供了激发动力。雷暴呈现椭圆形结构,长短半轴分别为13 km和10km,风暴中心强降雨区直径达5 km,雷暴前进方向是东北向,移动速度为5.9 m/s,在雷暴后部存在有组织的尾状条纹,结合雷暴结构诊断分析认为此尾迹是龙卷中心拖曳留下的痕迹。在雷暴外流区,冷空气反气旋式下降,周围的暖空气气旋式上升,两股气流的风切变导致大气内波的产生。此内波含有12个孤立子波,波长从450 m到237.5 m,平均波长为297.9 m。     

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.