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1.
Geometry, the Measure of the World   总被引:1,自引:1,他引:0  
This study considers the relationship between the approach to urban planning in Portugal up to the eighteenth century, and the effective process of urbanisation, from both a theoretical and practical perspective. Portuguese urban layout does not develop as a set of random shapes but rather arises from structured thinking by “urban makers” who are firmly grounded in the subject of geometry. Being able to measure the universe and codify it in drawings was one of the major scientific accomplishments of the age of Portuguese discoveries in the sixteenth century and the acquisition of such knowledge demanded a unique ability for abstraction which could not have simply emerged out of nothing. Portugal’s investment in the training of skilled professionals is made evident in treatises, manuals, dissertations, and cartography and iconography works. The interpretation of the ideas of Order and Space in urban design evolved through history in parallel with the evolution of philosophical and scientific thought. In fact, urban space is associated the search of the laws of the nature and the intelligibility of the cosmos.  相似文献   

2.
The zodiac is widely known as a band of twelve celestial constellations. It also contains a mathematical model for cosmographic depiction, based on observations of the sun, moon, and visible planets as they traverse the celestial ecliptic. Here wee consider the zodiac as a timepiece or calendar; how this system of planets and constellations emerges from elementary geometric patterns; and how these patterns inform the symbols of the zodiac and frame our world view.  相似文献   

3.
Abstract

Thomas H. Davenport and John C. Beck, The Attention Economy: Understanding the New Currency of Business, Boston, MA: Harvard Business School Press (2001), 253 pp.

Brad Hansen, The Dictionary of Computing and Digital Media: Terms and Acronyms, Wilsonville, OR: Franklin, Beedle, and Associates (1999), 543 pp.

Piotr Jankowski and Timothy Nyerges, Geographic Information Systems for Group Decision Making: Towards a Participatory Geographic Information Science, New York: Taylor and Francis (2001), 273 pp.

Jeffrey A. Rohlfs, Bandwagon Effects in High Technology Industries, Cambridge, MA: MIT Press (2001), 256 pp.  相似文献   

4.
Thomas H. Davenport and John C. Beck, The Attention Economy: Understanding the New Currency of Business, Boston, MA: Harvard Business School Press (2001), 253 pp.

Brad Hansen, The Dictionary of Computing and Digital Media: Terms and Acronyms, Wilsonville, OR: Franklin, Beedle, and Associates (1999), 543 pp.

Piotr Jankowski and Timothy Nyerges, Geographic Information Systems for Group Decision Making: Towards a Participatory Geographic Information Science, New York: Taylor and Francis (2001), 273 pp.

Jeffrey A. Rohlfs, Bandwagon Effects in High Technology Industries, Cambridge, MA: MIT Press (2001), 256 pp.  相似文献   

5.
Mark and Linda Keane describe a seminar that seeks to answer these questions with evidence of a renaissance of work in the twenty-first century that emanates or owes allegiance to mathematical explorations configured in Wright’s body of work. This seminar, The Geometry of Wright, offers students in the state of Wisconsin the opportunity to learn about Wright’s life, those who influenced him, and those whom he influenced. The combination of history, theory, mathematics, and design activities in this seminar offer students an opportunity to become aware of Wright’s use of geometry, understand its roots and precedents, and apply them to a project of their own. This whole language approach to learning embeds appreciation of mathematical principles and encourages students to apply geometric relationships in their own search for proportion and form.

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6.
7.
Problems of Information Transmission - We use Hamilton equations to identify most likely scenarios of long queues being formed in ergodic Jackson networks. Since the associated Hamiltonians are...  相似文献   

8.
9.
为进一步促进硬币的流通使用,扩大硬币的清分、卷包等专业机具的市场空间,形成硬币使用、流通互动的良好循环,通过硬币处理专用机具的设计与开发,为硬币流通和发挥社会支付功能提供保障。通过设备功能和工作原理的分析,介绍了包币机的各部分组成和构造。该设备应具有较好的应用前景。  相似文献   

10.
Students at the Istituto statale d’arte in Monza were asked to consider the Renaissance man as a model for interdisciplinary studies in a project in which they analyzed works of architecture and geometry texts of the Renaissance.  相似文献   

11.
Existing representations for multiattribute ceteris paribus preference statements have provided useful treatments and clear semantics for qualitative comparisons, but have not provided similarly clear representations or semantics for comparisons involving quantitative tradeoffs. We use directional derivatives and other concepts from elementary differential geometry to interpret conditional multiattribute ceteris paribus preference comparisons that state bounds on quantitative tradeoff ratios. This semantics extends the familiar economic notion of marginal rate of substitution to multiple continuous or discrete attributes. The same geometric concepts also provide means for interpreting statements about the relative importance of different attributes.  相似文献   

12.
基于区块链的数字货币发展现状与展望   总被引:1,自引:0,他引:1  
数字货币(Digital currency)作为区块链技术迄今为止最典型也最成功的应用, 得益于区块链分布式共识与去中心化信任的技术优势, 也促使了区块链技术与经济活动的深度融合, 并由此改变了数字社会的组织方式. 近年来, 无论是在基础理论研究方面, 还是在实践应用发展方面, 数字货币均呈现出了蓬勃向上的态势. 本文从技术创新、机制设计以及风险监管三个角度梳理了数字货币的主要研究问题, 详细阐述了基础支撑技术、隐私保护技术、共识机制、激励机制、币值机制、发行机制、风险分析、监管考量等方面的研究进展、存在问题及应用现状, 并展望了未来重点研究方向, 致力于为数字货币领域的研究提供有益借鉴.  相似文献   

13.
数据时效性判定问题的求解算法   总被引:1,自引:0,他引:1  
李默涵  李建中  高宏 《计算机学报》2012,35(11):2348-2360
数据的时效性问题是影响数据质量的重要因素之一.时效性差的数据会对企业决策和人们的日常生活带来许多不利影响,这使得判定数据的时效性成为必要.许多应用数据库中都没有完整、清洁、可用的时间戳,从而导致数据时效性的判定非常困难.冗余记录和时效约束能够在时间戳缺失的情况下有效地辅助恢复数据的时序关系,因而能够帮助数据时效性的判定.文中研究包含冗余记录的集合在给定时效约束下的时效性判定问题,并首次提出了时效性判定问题的求解算法.首先,文中定义了查询相关时效性和用户相关时效性.在判定查询相关时效性时,文中将查询归结为最新值查询和时效序列查询两类,并分别根据两类查询的特点,对每类查询定义了查询结果时效性和平均时效性.然后,文中提出了时效图的概念.利用时效图,文中给出了查询相关时效性和用户相关时效性判定问题的求解算法.最后给出了真实数据和虚拟数据上的实验结果,验证了文中算法较高的执行效率,并分析了各个参数对算法的影响.  相似文献   

14.
基于XML数据的通用路径表达式的查询   总被引:2,自引:0,他引:2  
郑刚 《微机发展》2004,14(11):94-97
查询重写是数据库研究的一个基本问题,它和查询优化、数据仓库、数据集成、语义缓存等数据库问题密切相关。同时,查询重写也是在关系数据库中存储和查询XML数据的关键问题。由于XML数据是元素嵌套和元素引用的,嵌套层数可以任意,并且模式和数据混合,因此XML的查询会涉及到广义路径表达式(GPE)。文中着重研究了如何解决XML数据的查询重写的方案,把含有广义路径表达式的XML查询语句重写为含有简单路径表达式(SPE)的XML查询语句,再转化为基于关系数据库的SQL语句。  相似文献   

15.
查询重写是数据库研究的一个基本问题,它和查询优化、数据仓库、数据集成、语义缓存等数据库问题密切相关.同时,查询重写也是在关系数据库中存储和查询XML数据的关键问题.由于XML数据是元素嵌套和元素引用的,嵌套层数可以任意,并且模式和数据混合,因此XML的查询会涉及到广义路径表达式(GPE).文中着重研究了如何解决XML数据的查询重写的方案,把含有广义路径表达式的XML查询语句重写为含有简单路径表达式(SPE)的XML查询语句,再转化为基于关系数据库的SQL语句.  相似文献   

16.
C.-S. Huang  C.-H. Hung  S. Wang 《Computing》2006,77(3):297-320
In this paper, we present a finite volume method for a two-dimensional Black-Scholes equation with stochastic volatility governing European option pricing. In this work, we first formulate the Black-Scholes equation with a tensor (or matrix) diffusion coefficient into a conservative form. We then present a finite volume method for the resulting equation, based on a fitting technique proposed for a one-dimensional Black-Scholes equation. We show that the method is monotone by proving that the system matrix of the discretized equation is an M-matrix. Numerical experiments, performed to demonstrate the usefulness of the method, will be presented.  相似文献   

17.
International Journal of Computer Vision - Registration maps or warps form a key element in Shape-from-Template (SfT). They relate the template with the input image, which contains the projection...  相似文献   

18.
GSM风靡全球     
GSM是欧洲开发的数字蜂窝移动电话标准。现已扩展到欧洲以外的亚洲、非洲、南美、中东以及澳大利亚等地区。有关专家预测,到2000年,欧洲的GSM移动电话用户将达到190O万甚至可达2300万。其发展前景甚为乐观。本文主要介绍当前GSM在世界各地的发展,并以表格的形式展示各地区的经营现状。  相似文献   

19.
On the Geometry of Visual Correspondence   总被引:1,自引:1,他引:0  
Image displacement fields—optical flow fields, stereo disparity fields, normal flow fields—due to rigid motion possess a global geometric structure which is independent of the scene in view. Motion vectors of certain lengths and directions are constrained to lie on the imaging surface at particular loci whose location and form depends solely on the 3D motion parameters. If optical flow fields or stereo disparity fields are considered, then equal vectors are shown to lie on conic sections. Similarly, for normal motion fields, equal vectors lie within regions whose boundaries also constitute conics. By studying various properties of these curves and regions and their relationships, a characterization of the structure of rigid motion fields is given. The goal of this paper is to introduce a concept underlying the global structure of image displacement fields. This concept gives rise to various constraints that could form the basis of algorithms for the recovery of visual information from multiple views.  相似文献   

20.
介绍了进钞、走钞通道直流电机的速度、电流双闭环控制系统控制方法.  相似文献   

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