基于行星历表的太阳系空间显示系统实现

为了研究太阳系中太阳和八大行星在不同参考系下实际的运动状态和运行轨迹,采用DE430行星历表计算出各天体太阳质心系中实际的状态向量,介绍了不同参考系之间的转换关系,并通过坐标转换进一步得到地球质心惯性系和地固系下天体的状态量。利用C#和SharpGL工具设计开发出太阳系三维空间显示系统,实现了不同参考系下各天体的坐标计算、动态显示、轨迹绘制和视点变化等功能,并进一步对系统进行了优化设计,软件运行结果表明,各天体在不同参考系中的运行状态不同,且有各自的运行规律。     

The Solar System Modeler

The authors undertook the Solar System Modeler project to improve comprehension and appreciation of the size, complexity, and splendor of the solar system. To do so, the Solar System Modeler must (1) accurately portray the orbital behavior of satellites, planets, comets, and other celestial bodies, and (2) function in a distributed virtual environment. Additionally, the system needs to: provide a flexible, 3D graphical user interface for immersive operation; assist the user in comprehending the state of the virtual environment; accurately portray the stars and their locations; graphically model all bodies throughout the solar system in 3D and to the same scale; and maintain an interactive frame rate. They describe how they met these requirements     

Oracular Functioning and Architecture of Five Ancient Apollo Temples Through Archaeoastronomy: Novel Approach and Interpretation

Five temples of Apollo on Mainland Greece and Ancient Ionia (Asia Minor), namely Delphi, Didyma, Hierapolis, Delos and Rhodes, have been examined regarding their functioning through astronomical orientation. Recent research has shown that the rise, setting, orbit and observation of certain constellations in the celestial sphere, as well as the solar stands, can be directly related to the architecture of the temple, i.e. construction, orientation, and keeping a calendar of the most important Apollonian oracular temple at Delphi. Here this lunar-solar-stellar configuration has been applied to other significant temples of Apollo. It is shown that at Didyma, Hierapolis and Delphi, the celestial pattern, as well as the landscape, local geology and architecture are similar, but different in temples without oracular function (Delos and Rhodes). Measurements were carried out by in situ readings and by Google Map tools.     

Composing by musical analog: a look at planetary orbits

Generating musical compositions using models from probability statistics, fractal geometry, and other nonlinear and chaotic systems, referred to by some composers as a mapping technique or mapping, is discussed. Composition based on celestial coordinates made audible through an interactive Pascal computer program that generates such coordinates for all the planets and the Earth's Moon as seen from any point on Earth for any given time frame is reported. The compositional environment is examined, the durational schemes used are described, and the composer's options are discussed     

Contours of diffusion of electronic data interchange in Finland: Overcoming technological barriers and collaborating to make it happen

Electronic Data Interchange (EDI)—despite its basic simplicity—forms a complex and inter-organizational innovation. This necessitates multiple points of observation and the use of multiple theoretical frames in accounting EDI diffusion processes. Based on field study data we deliver a multi-level account of EDI diffusion in Finland. The study clarifies how factors located on three levels of analysis can be applied to understand the unfolding of EDI adoption in different organizational constellations, here called diffusion patterns. We examine three families of diffusion patterns: local dyadic patterns; industry-wide networks; and national initiatives. Overall we discern five distinct diffusion patterns. The analysis of the five patterns demonstrates that EDI diffusion is a complex interplay of organizational, industry and institutional factors. On the theory plane our study calls for the need to orchestrate multi-level approaches to study the diffusion of complex, and networked technologies.     

Understanding Constellations of Technologies in Use in a Collaborative Nomadic Setting

This paper describes how people make sense of and use constellations of technologies in a nomadic setting, and it illustrates how maintaining and orchestrating a variety of applications and devices becomes an essential part of nomadic practices. The data were collected over a period of 3 years at a technical university by means of two field studies. Particular attention is drawn to how the situated orchestration of devices and applications within a group’s constellation reflects university students’ concern to manage their projects at a number of locations, as well as issues of time and circulation of resources. The analysis brings into focus how constellations of technologies emerge and dissolve within collaborative ensembles that only exist for the duration of a project, and how this can cause appropriation issues within groups.     

MySpace is your space? Examining self-presentation of MySpace users

The study examined the role of self-presentation on MySpace pages through the information users post on their sites. MySpace users were more comfortable with posting the broad pieces of information, like gender, race, zodiac sign, and hometown. They were not as willing to present personal information like income, whether they smoke or drank or groups they belonged to. Age and motivations for creating a page were major predictors of how much information people revealed about themselves.     

基于实值编码GA的卫星巡天扫描方法

巡天扫描是天文卫星进行天体观测的基础,但是使用传统方法很难实现全天球覆盖,并且会遇到能源输出瓶颈。因此,本文针对天文卫星巡天扫描所遇到的问题,提出了使用基于实值编码的遗产算法(Real-codedGA)对卫星飞行任务进行智能规划的方法。该算法智能规划飞行任务,与仅依靠被动的分段式扫描方法相比,很好解决了能源输出的问题,还大大缩短了巡天扫描的时间。从仿真结果来看,该模型是十分有效的。     

Zodiac算法的零相关-积分攻击

Zodiac算法是一种由一批韩国学者设计的分组密码算法,它是16轮平衡Feistel型的分组密码。首次从零相关-积分分析的角度评价了Zodiac算法的安全性,构造出算法的两类13轮零相关线性逼近,并据此给出了13轮零相关-积分区分器,对全轮Zodiac算法进行了零相关-积分分析,成功恢复出了144bit轮子密钥信息。结果显示:完整16 轮Zodiac-128/192/256算法的零相关-积分攻击的数据复杂度为2¹²⁰个选择明文,时间复杂度大约为2⁸²次16轮Zodiac算法加密,时间复杂度明显优于已有的积分攻击结果。     

DVB-S2标准中APSK星座选择与软解调设计

APSK是DVB-S2标准中新采用的信号星座以充分提高频谱利用率,减小卫星信道非线性失真的影响。APSK不像一般的其他星座那样固定不变,而是针对不同的频谱效率有不同的相对半径。本文将讨论在DVB-S2中如何选择APSK,并介绍一种针对其星座编码特点的软判断解调方案。     

基于概念格的天体光谱离群数据识别方法

在宇宙中, 寻求特殊的、未知的天体是人类探索宇宙奥妙所追求的目标之一, 天体光谱离群数据识别方法是实现该目标的有效手段之一. 将概念格中每个概念节点内涵描述为天体光谱数据特征子空间, 提出了一种天体光谱离群数据识别方法. 首先将概念节点的内涵缩减看作天体光谱特征子空间, 并依据稀疏度系数阈值确定稀疏子空间; 其次对于稀疏子空间, 依据稠密度系数判定祖先概念节点内涵是否为稠密子空间, 进而判断出概念节点外延中包含的数据对象是否为天体光谱离群数据; 最后以离散化天体光谱数据作为形式背景, 实验验证了利用该方法识别出的天体光谱离群数据是准确的、完备的和有效的.     

Labeled point pattern matching by fuzzy relaxation

A method of matching labeled point patterns is described on the basis of a fuzzy relaxation. The method is applicable to labeled point patterns which differ by geometrical transformations, such as translation, rotation and scale change. In this method, the point pairs are considered to be the pattern primitives. The pattern primitives are geometrically transformed in the process of relaxation so as to minimize a measure of mismatch between the primitive pairs. The compatible primitive pairs between the two labeled point patterns are established after only a few iterations of relaxation and the corresponding points are obtained from the primitive pairs. As an example, the method is applied to the matching of constellations.     

Using Key Diagrams to Design and Construct Roman Geometric Mosaics?

The complexity shown by some geometrical patterns of Roman mosaics and the high quality of their realization lead to think that for such patterns, unlike scenes with human or animal figures, a model of the general pattern was certainly not sufficient to guide the setting up; in order to answer this question one is led to conjecture the existence of diagrams (key diagrams) with which the craftsman, by looking at them, is able to identify (and/or remember) the geometrical structure of a basic element of the general pattern, as well as a way for constructing it – and possibly the whole pavement – with his usual instruments. This hypothesis is applied to some patterns which were well spread over the Roman world. The present study aims at showing how a given key diagram can apply to varied patterns and, conversely, how the making of a given complex pattern can rely on several articulated key diagrams.     

Knowledge transfer in pair programming: An in-depth analysis

Whilst knowledge transfer is one of the most widely-claimed benefits of pair programming, little is known about how knowledge transfer is achieved in this setting. This is particularly pertinent for novice−expert constellations, but knowledge transfer takes place to some degree in all constellations. We ask “what does it take to be a good “expert” and how can a “novice” best learn from a more experienced developer?”. An in-depth investigation of video and audio excerpts of professional pair programming sessions using Interaction Analysis reveals: six teaching strategies, ranging from “giving direct instructions” to “subtle hints”; and challenges and benefits for both partners. These strategies are instantiations of some but not all teaching methods promoted in cognitive apprenticeship; novice articulation, reflection and exploration are not seen in the data. The context of pair programming influences the strategies, challenges and benefits, in particular the roles of driver and navigator and agile prioritisation which considers business value rather than educational progression. Utilising these strategies more widely and recognizing the challenges and benefits for both partners will help developers to maximise the benefits from pairing sessions.     

自适应P值映射的惯性/天文角度组合导航算法

惯性/天文角度组合导航在应用于高动态飞行器时,动态飞行环境变更会导致星光角度观测量发生程度不等的偏差,使得常规组合滤波方法误差显著增大.为此,本文提出了基于P值映射的观测质量自主评估及自适应滤波方法,并应用于惯性/天文角度组合导航系统.该方法根据历年可见导航星情况分解冗余观测子集,再由P值度量其含有观测量偏差的显著性水平.在此基础上,通过遍历每颗导航星所隶属子集得到其观测量质量值,最后对惯性/天文角度组合滤波增益进行自适应调节.仿真结果表明,本文方法能够实现天文高度角观测质量的自主在线评估,有效提高星光观测质量下降情况下惯性/天文角度组合导航的精度和适应性.     

基于天文/GPS的HEO卫星自主导航方法

为了实现大椭圆轨道(HEO)卫星高精度自主导航,提出一种将直接敏感地平天文导航与全球定位系统(GPS)相结合的组合导航方法.首先,分析卫星轨道??2运动模型及其所受空间摄动,建立卫星轨道动力学模型;然后,分析单一使用天文导航和GPS的优缺点,根据HEO卫星对GPS的可见性,提出在远地点只采用天文导航,而在近地点采用以天文导航为主、适时引入GPS信号进行位速测量辅助修正的方法.通过计算机仿真和结果分析表明了所提出的设计方法导航精度比单一天文导航提高72.4%～85.6%.     

基于多圆迭代和H∞ 滤波的捷联/天文定位算法研究

针对现有天文定位算法的缺点,提出一种多圆交汇迭代天文定位算法.该算法能够充分利用可观测恒星,同时能计算出定位误差协方差阵.针对提出的算法定位误差非线性的特点,提出了基于H∞滤波器的捷联/天文自适应组合导航算法,根据定位误差协方差阵实现量测自适应.仿真结果表明,天文定位算法模型准确,组合导航算法定位精度小于20m,定位误差稳定.     

Symmetry Detection Using Feature Lines

In this paper, we describe a new algorithm for detecting structural redundancy in geometric data sets. Our algorithm computes rigid symmetries, i.e., subsets of a surface model that reoccur several times within the model differing only by translation, rotation or mirroring. Our algorithm is based on matching locally coherent constellations of feature lines on the object surfaces. In comparison to previous work, the new algorithm is able to detect a large number of symmetric parts without restrictions to regular patterns or nested hierarchies. In addition, working on relevant features only leads to a strong reduction in memory and processing costs such that very large data sets can be handled. We apply the algorithm to a number of real world 3D scanner data sets, demonstrating high recognition rates for general patterns of symmetry.     

Curve Fitting in Architecture

It used to be popular to draw geometric figures on images of paintings or buildings, and to propose them as an “analysis” of the observed work, but the tradition lost some credit due to exaggerated (golden section) interpretations. So, how sure can an art or mathematics teacher be when he wants to propose the profile of a nuclear plant as an example of a hyperboloid, or proportions in paintings as an illustration of the presence of number series? Or, if Gaudi intended to show chain curves in his work, can the naked eye actually notice the difference between these curves and parabolas? The present paper suggests applying the “least squares method”, developed in celestial mechanics and since applied in various fields, to art and architecture, especially since modern software makes computational difficulties nonexistent. Some prefer jumping immediately to modern computer machinery for visual recognition, but such mathematical overkill may turn artistic minds further away from the (beloved!) tradition of geometric interpretations.