1,720,964 research outputs found
Photovoltaic performance of amorphous silicon flexible solar modules under mechanical loading
No full textThe applications of photovoltaic devices can be significantly expanded by directly integrating them into structures. Solar cells integrated into structures can help to power a variety of devices such as structural monitoring sensors and unmanned aerial vehicles (UAVs). However, little work has been reported in the literature on the performance of solar cells under deformation. Thus, a thorough investigation on the photovoltaic behavior of solar modules under mechanical loading is necessary in order to provide the optimal integration conditions for practical applications. The photovoltaic performance of commercially available amorphous silicon solar modules was tested under applied mechanical stresses. The current density-voltage characteristics were measured at increasing stress levels during a uniaxial tensile test. As strain increased, the short circuit current density decreased, and at strains greater than 1.4%, the fill factor, and maximum power point degraded. The performance degradation is attributed to micro-structural changes in the form of cracking under applied stress. These results are required to determine the allowable loading conditions and failure mechanism in solar module integrated structural systems
Performance of thin-film lithium energy cells under uniaxial pressure
No full textThe objective of this study was two-fold. The first objective
was to determine if the all-solid-state thin-film lithium energy
cells could withstand the minimal 550 kPa uniaxial pressure
required for composite manufacturing, which both specimens
successfully did. The second objective was to determine the
upper boundary uniaxial pressure limit of operation for the
all-solid-state thin-film lithium energy cells. The two all-solid-
state thin-film lithium energy cells tested in the present
study under uniaxial pressure performed well even when
subjected to uniaxial pressures up to about 2.0 MPa. However,
pressures higher than this value led to their degradation.
The observed degradation was due to the mechanical
failure of the sealant. Above this pressure, the sealant was
squeezed out of the space between the two mica substrates
and the lithium-metal anode layer, which in turn allowed the
ambient air to penetrate into the energy cell core, thus leading
to the rapid degradation of the charge and discharge performance
and the ultimate demise of the energy cell. We found
out that, within the observed range, uniformly distributed packaging characteristics, we found that allsolid-
state thin-film energy cells charge/discharge
cycles under upwardly increasing
uniform uniaxial pressure are extraordinarily
robust and resilient to the effects of uniaxial,
uniformly distributed uniaxial pressure had little or no effect on the charge/discharge
performance of the all-solid-state thin-film lithium energy
cells. Other power charge/draws outside of 1 mAh were
not of interest in this study for the reasons already pointed
out, albeit that they may be considered for future studies.
Apart from other considerations for failure due to the current and
constant power charge/sink of 1mAh. If the
overall structure of the energy cell is mechanically
robust, i.e., of high structural integrity,
the maximum pressure that can be
imposed is expected to be much higher than
the maximum values noted earlier.
The present study indicates that all-solidstate
thin-film energy cells can be used as an
integral part of a load-bearing multifunctional,
smart material structure if their packaging
is of sufficiently high structural integrity.
Hence, the goal of using fiber reinforced
laminated composites as the packaging
material for all-solid-state thin-film batteries
in multifunctional smart materials structures
is well within reach
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
Investigation of effective material properties in composites with internal defect or reinforcement particles
No full textAbstractThis paper is concerned with the investigation of the effective material properties of internally defective or particle-reinforced composites. An analysis was carried out with a novel method using the two-dimensional special finite element method mixing the concept of equivalent homogeneous materials. A formulation has been developed for a series of special finite elements containing an internal defect or reinforcement in order to assure the high accuracy especially in the vicinity of defects or reinforcements. The adoption of the special finite element can greatly simplify numerical modeling of particle-composites. The numerical result provides the effective material properties of particle-reinforced composite and explains that the size of particles has great influence on the material properties. Numerical examples also demonstrate the validity and versatility of the proposed method by comparing with existing results from literatures
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