307,011 research outputs found
Novel numerical optimisation of the Hohmann Spiral Transfer
No full textAs the revenue of commercial spacecraft platforms is generated by its payload, of which the capacity is maximised when fuel-mass is minimised, there is great interest in ensuring the fuel required for the trajectory to deliver the satellite to its working orbit is minimum. This paper presents an optimisation study of a novel orbit transfer, recently introduced by the authors through an analytical analysis, known as the Hohmann Spiral Transfer . The transfer is analogous to the bi-elliptic transfer but incorporating high and low-thrust propulsion. This paper has shown that substantial fuel mass savings are possible when utilizing the HST. For a transfer to Geostationary Earth Orbit it is shown that a fuel mass saving of approximately 320 kg (~ 5 - 10% of mwet ) is possible for a wet mass of 3000-6000 kg – whilst satisfying a time constraint of 90 days. Several trends in the gathered data are also identified that determine when the HST with high or low-thrust plane change should be used to offer the greatest fuel mass benefit
Análise e simulação computacional de órbita de transferência de Hohmann pelo método de Euler
Get PDFIn this monograph a study is made on the basic principles of Celestial Mechanics, using concepts of Newtonian physics. An introductory approach is presented on orbital transfer maneuvers, with emphasis on the Hohmann Transfer method. The Hohmann method is a rather simple technique, used in orbit transfer situations where it is desired to optimize the fuel consumption of a spacecraft. The method consists in the application of two pulses, generating an elliptical orbit, where it is desired to change the radius of this orbit to another of defined radius. The system of equations is solved analytically when considering the interaction of only 2 bodies, for 3 or more bodies the equations are solved numerically. Computational simulations are performed using the numerical method of Euler to solve the equations of trajectory of the body dynamically. The simulations are described in 5 different scenarios, where each scenario is configured to demonstrate the main steps of Hohmann transfer and the effects of perturbations in the orbit. The results are presented through graphs obtained for analysis.Nesta monografia faz-se um estudo sobre os princípios básicos da Mecânica Celeste, utilizando conceitos da física Newtoniana. Apresenta-se uma abordagem introdutória sobre manobras de transferência orbital, com ênfase no método de Transferência de Hohmann. O método de Hohmann é uma técnica bastante simples, utilizada em situações de transferência de órbita onde se deseja otimizar o consumo de combustível de um veículo espacial. O método consiste na aplicação de dois impulsos, gerando uma órbita elíptica, onde se deseja alterar o raio desta órbita para outro de
raio definido. O sistema de equações é resolvido analiticamente quando considerado a interação de somente 2 corpos, para 3 ou mais corpos as equações são resolvidas numericamente. É realizado simulações computacionais utilizando o método numérico de Euler para resolução das equações de trajetória do corpo de forma dinâmica. As simulações estão descritas em 5 cenários distintos, onde cada cenário é configurado para demonstrar as principais etapas de transferência de Hohmann e os efeitos de perturbações na órbita. Os resultados são apresentados através de gráficos obtidos
para análise.Trabalho não financiado por agência de fomento, ou autofinanciad
Unsere Schuleinrichtungen und die Reformbestrebungen im Lichte des Erziehungsprinzips und der Zeitforderungen
No full textvon L. Hohman
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Beschreibung, Theorie und Gebrauch des Präcisions-Polarplanimeters (Patent Hohmann und Coradi)
No full textvon Friedrich Hohman
Ander(e)s bilden : "N.O.Body" als queere, kuratorische Intervention in Magnus Hirschfelds "Bilderteil"
No full textAls eine künstlerisch-wissenschaftliche Praxis, die im Sinne des Verlernens hegemonialen Wissens Bedeutung veruneindeutigt, anstatt sie zu fixieren, versteht Philipp Hohmann in seinem Beitrag das Kuratieren. Er untersucht die künstlerische Arbeit "N.O.Body" von Pauline Boudry und Renate Lorenz, die in ihrer gleichnamigen Installation eine Auswahl der Abbildungen versammeln, anhand derer Magnus Hirschfeld in seiner 1926 bis 1930 erschienen "Geschlechtskunde" sein Einordnungsprinzip der sexuellen Zwischenstufen illustrierte. Dem pädagogisch-aufklärerischen Impetus des sog. 'Bilderteils', dem das Motto vorangestellt ist, "Bilder sollen bilden", stellen Baudry/Lorenz mit ihrer Re-Konstellation der Bilder, ihrem Film und der Performance, die Teil der Installation ist, eine "Affirmation als Methode der Kritik [gegenüber], um mit, gegen und auch jenseits dieser Bilder anders oder Andere(s) zu bilden" (Hohmann)
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
Get PDFThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
Zur Erkundung eines Meso-Ortes. Raucher*innenecken an Schulen
Get PDFHohmann S, Neuhaus T. Zur Erkundung eines Meso-Ortes. Raucher*innenecken an Schulen. PraxisForschungLehrer*innenBildung. Zeitschrift für Schul- und Professionsentwicklung. 2022;4(1):214-227
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