364,678 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Space is the machine: a configurational theory of architecture
No full textSince The social logic of space was published in 1984, Bill Hillier and his colleagues at University College London have been conducting research on how space features in the form and functioning of buildings and cities. A key outcome is the concept of ‘spatial configuration’ — meaning relations which take account of other relations in a complex. New techniques have been developed and applied to a wide range of architectural and urban problems. The aim of this book is to assemble some of this work and show how it leads the way to a new type of theory of architecture: an ‘analytic’ theory in which understanding and design advance together. The success of configurational ideas in bringing to light the spatial logic of buildings and cities suggests that it might be possible to extend these ideas to other areas of the human sciences where problems of configuration and pattern are critical
Space is the machine, part one: theoretical preliminaries
No full text‘Theoretical Preliminaries’ deals with the most basic of all questions which architectural theory tries to answer: what is architecture, and what are theories, that they can be needed in architecture? In the first chapter, ‘What architecture adds to building’, the key concepts of the book are set out on the way to a definition of architecture. The argument is that in addition to functioning as bodily protection, buildings operate socially in two ways: they constitute the social organisation of everyday life as the spatial configurations of space in which we live and move, and represent social organisation as physical configurations of forms and elements that we see. Both social dimensions of building are therefore configurational in nature, and it is the habit of the human mind to handle configuration unconsciously and intuitively, in much the same way as we handle the grammatical and semantic structures of a language intuitively. Our minds are very effective in handling configuration in this way, but because we do work this way, we find it very difficult to analyse and talk rationally about the configurational aspects of things. Configuration is in general ‘non-discursive’, meaning that we do not know how to talk about it and do not in general talk about it even when we are most actively using it. In vernacular buildings, the configurational, or non-discursive, aspects of space and form are handled exactly like the grammar of language, that is, as an implication of the manipulation of the surface elements, or words and groups of words in the language case, building elements and geometrical coordinations in building. In the vernacular the act of building reproduces cultural given spatial and formal patterns. This is why it seldom seems ‘wrong’. Architecture, in contrast, is the taking into conscious, reflective thought of these non-discursive and configurational aspects of space and form, leading to the exercise of choice within a wide field of possibility, rather than the reduplication of the patterns specific to a culture. Architecture is, in essence, the application of speculative and abstract thought to the non-discursive aspects of building, and because it is so, it is also its application to the social and cultural contents of building.
Chapter 2, ‘The need for an analytic theory of architecture’, then takes this argument into architectural theory. Architectural theories are essentially attempts to subject the non-discursive aspects of space and form to rational analysis, and to establish principles to guide design in the field of choice, principles which are now needed as cultural guidance is no longer automatic as it is in a vernacular tradition. Architectural theories are both analytic in that they always depend on conjectures about what human beings are like, but they are also normative, and say how the world should be rather more strongly than they say how it is. This means that architecture can be innovative and experimental through the agency of theories, but it can also be wrong. Because theories can be wrong, architects need to be able to evaluate how good their theories are in practice, since the repetition of theoretical error - as in much of the modernist housing programme - will inevitably lead to the curtailment of architectural freedom. The consequence of this is the need for a truly analytic theory of architecture, that is, one which permits the investigation of the non-discursive without bias towards one or other specific non-discursive style.
Chapter 3, ‘Non-discursive technique’, outlines the prime requirement for permitting architects to begin this theoretical learning: the need for neutral techniques for the description and analysis of the non-discursive aspects of space and form, that is, techniques that are not simply expressions of partisanship for a particular type of configuration, as most architectural theories have been in the past. The chapter notes a critical difference between regularities and theories. Regularities are repeated phenomena, either in the form of apparent typing or apparent consistencies in the time order in which events occur. Regularities are patterns in surface phenomena. Theories are attempts to model the underlying processes that produce regularities. Every science theorises on the basis of its regularities. Social sciences tend to be weak not because they lack theories but because they lack regularities which theories can seek to explain and which therefore offer the prime test of theories. The first task in the quest for an analytic theory of architecture is therefore to seek regularities. The first purpose of ‘non-discursive technique’ is to pursue this task
Mapping the Discipline of the Olympic Games An Author-Cocitation Analysis
Full text linkThe authors conducted an author cocitation analysis on prominent authors writing about the Olympics during the 1990s. Author cocitation is an established bibliometric technique that can be used to measure the relative similarities of topics written about by the cited authors. This enables a visual representation of the “intellectual space” of the discipline, in this case the Olympics, to be created for the period under review. So core and peripheral research areas are identified, along with their major contributors. The representation appears as a two-dimensional cluster-enhanced map. Subject expertise was then applied to the results to place labels on the generated clusters of authors and their topics
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Meaning of Concurrent Space Engineering in Phase B
No full textNowadays, Concurrent Engineering (CE) is a well-established process for pre-development phases within the space sector and applied in international agencies, in industry and academia since several years. Recently the high efficiency of a Phase 0/A CE-process could be verified in many studies at the Concurrent Engineering Facility (CEF) of the German Aerospace Center (DLR). The decrease of cost, time and inconsistencies in system design is apparent. This is a result amongst others out of the participation of all domains related to the space mission, the use of a common data model and very frequent iterations in the development process.
The DLR Institute of Space Systems has already gained first experiences of Phase B Concurrent Engineering in the frame of the DLR Compact-Satellite project as well as within two CE studies related to CubeSats. These activities have been executed primarily on an empirical basis. It has been done by addressing the needs of the respective project status and simultaneously working out the desired results with all relevant team members in the DLR CEF.
In order to elaborate a meaningful approach for supporting higher space project development phases applying CE, an intensive discussion of the stakeholder’s needs, expected results and possible design processes is required. The actual questions deal with aspects of preliminary and detailed design, with the major differences between Phase A and Phase B activities in view of CE, with tools commonly used by the domain experts and how these could be linked to the CE-process and a central data model. Are generic processes required or rather different, dedicated types of CE activities along the Phase B timeline? Are they similar or not for system design, subsystem issues or associated topics such as verification and validation planning, cost estimation or requirement reviews? Do these activities and their objectives have to be pre-defined and shall they be implemented entirely in the project plan already at a very early stage? Is it advisable to keep margin with respect to the schedule for trouble-shooting tasks like a potential payload/bus interface re-design study?
In the frame of corresponding work a discussion baseline for the long list of aspects related to CE in higher project phases is provided, by mainly introducing the basic characteristics, requirements and constraints of Phase B design and the comparability to earlier and also higher phases. Furthermore, a set of pros and cons are described for scenarios of how, when and where CE could be applied in Phase B. Finally, initial proposals are given for potential adaptions of organizational and process-related aspects such as the definition of a CE activity timeline, including the variation of design iteration cycles, the team set-up for dedicated sessions and how the H/W and S/W infrastructure could be prepared. Achieving a common understanding of these issues is an important step for more sustainable and efficient space product development applying the methodologies of CE also in Phase B and beyond
Trailblazing through a Knowledge Space of Science: Forward Citation Expansion in CiteSeer
Full text linkUnderstanding emerging trends and patterns in science and technology is essential not only to scientists and engineers in their own fast-advancing fields but also to a wide variety of individuals and organizations who are also interested in tracking the development of thematic topics. This is a challenging task because many existing tools are not particularly designed to deal with the dynamics of intellectual structures that transcend the boundaries of individual documents or isolated topics. In this article, we introduce a conceptual and operational platform that extends the traditional notion of traveling along individual citation pathways and defines operators for recursive and holistic theme expansion based on citation connectivity. We describe the implementation of a forward expansion operator and illustrate its potential with the CiteSeer metadata. In addition, we integrate the forward expansion operators with information visualization techniques
A weakly Stegall space that is not a Stegall space
No full textA topological space X is said to belong to the class of Stegall (weakly Stegall) spaces if for every Baire (complete metric) space B and minimal usco φ : B2X, φ is single-valued at some point of B. In this paper we show that under some additional set-theoretic assumptions that are equiconsistent with the existence of a measurable cardinal there is a Banach space X whose dual, equipped with the weak topology, is in the class of weakly Stegall spaces but not in the class of Stegall spaces. This paper also contains an example of a compact space K such that K belongs to the class of weakly Stegall spaces but ( C(K), weak) does not
Photon-Sail Trajectories Towards Exoplanet Proxima b
No full textThis paper investigates trajectories within the Alpha Centauri system to reach planet Proxima b. These trajectories come in the form of connections between the classical Lagrange points of Alpha-Centauri’s binary system (composed of the stars Alpha Centauri A and B, AC-A and AC-B) and the classical Lagrange points of the Alpha Centauri C (AC-C)/Proxima b system. These so-called heteroclinic connections are sought using a patched restricted three-body problem method. A genetic algorithm is applied to optimize the linkage conditions between the two three-body systems, focusing on minimizing the position, velocity, and time error at linkage. Four different futuristic, graphenebased sail configurations are used for the analyses: two sails with a reflective coating on only one side of the sail with lightness numbers equal to β = 100 and β = 1779, and two sails with a reflective coating on both sides (again, considering β = 100 and β = 1779). Results from the genetic algorithm show that, for example, a transfer from the L2-point in the AC-A/AC-B system to the L1-point in the AC-C/Proxima b system can be accomplished with a transfer time of 235 years for the one-sided graphene-based sail with β = 1779.Astrodynamics & Space MissionsAerospace Engineerin
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