1,720,962 research outputs found
ISSUES IN REDUCED ORDER MODELING OF MECHANICAL SYSTEMS
No full textA common modeling technique in investigating the dynamics of mechanical systems is the use of second order matrix differential equations. In such a formulation, the coefficient matrices contain the physical mass, damping, and stiffness parameters of the sys- tem, which in turn affect the vibrational parameters such as the nat- ural frequencies and modeshapes. The construction of a mass-- damping--stiffness model based on material properties and the systemís geometry, as done in finite element analysis, is a relatively straight forward procedure and is widely employed. The identifica- tion of such a model from the measured dynamic response, on the other hand, has proven to be a tough challenge, and it is often re- ferred to as the ëëinverse vibration problem".
Recently the authors have presented a solution to this problem based on identified state space realizations. This approach uses measured input and output data in the Observer/Kalman filter IDen- tification (OKID) algorithm to identify the Markov parameters of the system, which are then used in the Eigensystem Realization Algo- rithm (ERA) to realize the discrete time first-order system matrices. This initial state space model is further refined by minimizing the output error between the measured and predicted response using a non-linear optimization approach based on sequential quadratic programming techniques. Once the final form of the state space model is obtained, the physical parameters of the second-order (fi- nite element) model are retrieved from this state space model using complex eigenvalues and properly scaled complex eigenvectors. This solution has proven to be more flexible and general than the
80
JEM,128(3),340-350.
previously presented solutions to the problem, and it has been used effectively in estimating the physical parameters of various models. On the other hand, even though the requirements on the number of available sensors and actuators for a full order identification has been improved with the aforementioned solution, the question of obtaining reduced order models in the absence of full instrumenta- tion has not been fully investigated yet. This study represents a first attempt at providing some alternate formulations that address the problem of insufficient instrumentation. The discussions are devot- ed to the review of the full order modeling problem, effects of insuf- ficient instrumentation, possible reduced order modeling schemes, and alternate formulations that can be developed by employing as- sumptions that are often used in the literature, such as having a di- agonal mass matrix and/or a classically damped system
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
Variations on the Author
Full text link“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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
