1,721,307 research outputs found
Design and development of a multimodal self adjusting vibration energy harvesting system / Lim Chin Seong
No full textVibration energy harveting devices have the potential to replace batteries in powering remote sensors. However,the bandwidth of such devices is typically very narrow, and thus. only abble to generate sufficient power when the excitation frequency is at the natural frequency of the device. This research aims to design, build and test the behavior of a antilever beam that has the capability to self-tune its natural frequency mechanically.The self-turning mechanism is designed based on the observation that vibration causes freely supported disc to rotate, and the mass distribution of an asymmetrical disc changes with the rotary position of the disc, which in turn changes the natural frequency of the cantilever beam. Teh self-tuning mechanism is found to increase the bandwidth of the testing apparatus as compared to the bandwith without self-tuning. An improvement of up to 318% was observed between the measured vibration magnitudes of the self-tuning system vs the system without self-tuning. The vibration magnitude is characterized by RMS Acceleration and Displacement as measured by accelerometers and laser displacement sensor. It is expectedthat higher Acceleration and Displacement would couse more electrical power to be generated when the self-tuning mechanism is combinedwith energy conversion devices such as piezo-electric elements
Studies on the effect of nanosized ceramic filler in poly (vinyl alcohol)-lithium perchlorate based polymer electrolytes / Lim Chin Shen
Get PDFIn this study, three polymer electrolyte systems are prepared by means of solution casting technique. These polymer electrolytes consist of poly (vinyl alcohol) (PVA) (host polymer), lithium perchlorate (LiClO4) (dopant salt) and different types of ceramic fillers [antimony trioxide (Sb2O3) and titanium oxide (TiO2)]. The prepared polymer electrolyte samples with various wt. % of filler content were subjected to X-ray diffraction (XRD), impedance spectroscopy, morphological, and thermal studies. 60 wt. % of PVA and 40 wt. % of LiClO4 shows the highest ionic conductivity of 2.6110-5 S cm-1 at room temperature. The highest ionic conductivity increased to 9.5110-5 S cm-1 and 1.3010-4 S cm-1 with the addition of Sb2O3 and TiO2, respectively. The prepared polymer electrolyte systems obey the Arrhenius rule. XRD analyses reveal the suppression in crystallinity of PVA upon the addition of LiClO4 and inorganic fillers. Incorporation of Sb2O3 and TiO2 shifts the glass transition temperature, Tg to a lower temperature at which the flexibility of polymer backbone was enhanced. SEM images reveal the modification of surface morphology upon the addition of LiClO4 and inorganic fillers. TGA studies indicate that the thermal stability of polymer electrolyte increases significantly when Sb2O3 and TiO2 were introduced to polymer electrolyte which results in the second onset decomposition temperature being shifted to higher temperature. Electric double layer capacitors (EDLCs) were prepared by sandwiching the polymer thin films with two carbon electrodes. Results reveal that the polymer electrolyte with fillers attains higher specific capacitance compared to polymer electrolyte without filler. The prepared EDLCs have the capacitance retention over 90% which demonstrates the EDLC cells have excellent electrochemical stability
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
Persepsi guru sekolah rendah terhadap keberkesanan kursus dalam perkhidmatan bagi pengajaran mata pelajaran sains di daerah Hulu Perak, Perak / Lim Chin Hoe
Get PDFVariations 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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