1,722,575 research outputs found
Men at LAMSA Gathering
No full textPhotograph of fourteen men lined up side by side. All of the men are wearing full suits and neckties, five of the men are wearing eyeglasses and one wears sunglasses. One man is holding a hat by his side. In the background is a poster with "LAMSA" on it
Mujeres sentadas en el mostrador de LAMSA en el aeropuerto
No full textLAMSA (Líneas Aéreas Mexicanas, S.A.
Bifurcations in Latch-Mediated Spring Actuation (LaMSA) Systems
Get PDFIn nature, different species of smaller animals produce ultra-fast movements
to aid in their locomotion or protect themselves against predators. These
ultra-fast impulsive motions are possible, as often times, there exist a small
latch in the organism that could hold the potential energy of the system, and
once released, generate an impulsive motion. These types of systems are
classified as Latch Mediated Spring Actuated (LaMSA) systems, a
multi-dimensional, multi-mode hybrid system that switches between a latched and
an unlatched state. The LaMSA mechanism has been studied extensively in the
field of biology and is observed in a wide range of animal species, such as the
mantis shrimp, grasshoppers, and trap-jaw ants. In recent years, research has
been done in mathematically modeling the LaMSA behavior with physical
implementations of the mechanism. A significant focus is given to mimicking the
physiological behavior of the species and following an end-to-end trajectory of
impulsive motion. This paper introduces a foundational analysis of the
theoretical dynamics of the contact latch-based LaMSA mechanism. The authors
answer the question on what makes these small-scale systems impulsive, with a
focus on the intrinsic properties of the system using bifurcations. Necessary
and sufficient conditions are derived for the existence of the saddle fixed
points. The authors propose a mathematical explanation for mediating the latch
when a saddle node exists, and the impulsive behavior after the bifurcation
happens.Comment: Accepted to the 26th International Symposium on Mathematical Theory
of Networks and Systems. 8 pages, 4 figure
Control in Latch-Mediated, Spring-Actuated (LaMSA) systems
No full textInsects and other small organisms are capable of impressive impulsive motions, producing extraordinarily high forces for their tiny body masses. Jumping is one such motion where these insects achieve high velocities and accelerations, and this jumping behaviour can be replicated via Latch-Mediated Spring-Actuated (LaMSA) mechanisms. However, the ability to control jumping behaviour in engineered systems is currently limited. This paper examines the latch-spring interface as a potential area for control in a small jumping LaMSA robot. Different latch geometries are used to produce varied jumping behaviour across the applied motor voltage range, and a preliminary dynamic analysis of the unlatching process is presented. Deeper understanding of latch dynamics could provide engineers with an alternate approach to designing small robots within system constraints in future. Conventionally, latches are removed from LaMSA systems by an external force or actuator. However, we show that the internal spring force inherent in the system can contribute to the latch removal process, especially in small scale systems where external actuators alone may be weaker. This helps circumvent the limitations of the available low torque motors at this size scale, allowing the jumper design presented in this work to achieve a range of take-off velocities from 1.78m/s to 2.23m/s.Bachelor of Engineering (Mechanical Engineering
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
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
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
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