1,720,959 research outputs found
Synthesis of graphene using waste cooking palm oil (WCPO) by double thermal chemical vapour deposition (DTCVD) method for humidity sensor application / Robaiah Mamat
Get PDFThe lack of waste cooking palm oil management especially from fried chicken is becoming problematic issues where it disposing to soil, kitchen sink, drainage system, river and others, which cause pollutions effect. Nowadays, graphene grows to be new types of materials for manufacturing humidity sensors with low cost and eco-friendly technology in industry. Conventionally, graphene was synthesized from fossil fuels with high toxicity such as methane, acetylene and ethanol benzene, xylene, toluene, etc. The costs of these carbon sources are expensive and non-renewable. Therefore, efforts by utilizing carbon source from natural source such as grass, plastics, vegetation waste, sugarcane, tea-tree extract, sesame oil, camphor oil, and palm oil have been studied. In this research, abundant of waste cooking palm oil (WCPO) was used as a natural carbon source for synthesis graphene. It is as alternative to conserve the environment and low-cost method. WCPO was used as a precursor and nickel foil was used as a substrate. Graphene was successfully deposited on nickel substrate by using double thermal chemical vapour deposition, (DTCVD) method. All samples were prepared at different cycle precursor (refined, first cycle, second cycles and third cycles), amount of precursor (5 μl, 10 μl, 50 μl, and 100 μl), temperature precursor (250°C-450°C), deposition temperature (850°C-1100°C), and synthesis time (5-30 minutes), respectively. The results indicate that graphene prepared at third cycles precursor with 10 μl at 350°C of temperature precursor, 1000°C of deposition temperature and 20 minutes deposition time have good arrangements graphene network structure with large active area and introduce less boundary defects. Additionally, the full width half maximum, (FWHM) of the (002) peak become larger (0.32) which indicate decreased size of the crystallite (25.24 nm), and decreases number of graphene layers (9 layers). Moreover, at the optimum parameter the formation of active carbon species (dehydrogenation) and diffusion of active carbon on the surface was energetic and increase the percentage of reflectance (66.37%). The growth of graphene film at an optimum parameter, resulting in the highest of I2D/IG (0.41) and lowest of ID/IG (0.02) since, the carbon atoms segregate and form multi layers graphene with high crystalline and low defective structure. Subsequently, the optimum sample of graphene on nickel substrate was transferred onto glass substrate by Poly (methyl methacrylate), (PMMA) polymer for humidity sensor application. The response-recovery time, sensitivity, and repeatability of humidity sensor were determined using humidity chamber. The adsorption (response time) and desorption (recovery time) process takes several hundred second, 597 and 503 second respectively. These attributed to the sheet resistant is height in multilayer graphene. However, it is found that the sensitivity of multilayer graphene-based humidity sensor using WCPO has potential to develop as sensing material in humidity sensors and comparable with other material that sensitive to water molecules. It shows the sensitivity at 40% to 90% RH, is 365%. In the meantime, humidity sensor using graphene quantum dots, rGO/Ls, graphene/polypyrrole, and SZO/SnO2 sensor, the sensitivity are, 390, 298, 138, and 67.1%, respectively. Multilayer graphene-based humidity sensor using WCPO remains constant and similar at fifth cycles, indicating that sensor exhibits stable and excellent repeatability and have potential as a sensing material based with low cost and renewable energy
Synthesis and characterization of rare earth elements cerium and dysprosium doped low density bi-2223 superconductor / Robaiah Mamat
No full textSo far, there are limited reports on the investigation on the influence of the rare earth doped low density Bi| 6Pbo 4Sr2Ca2Cu3 0 y system where cerium and dysprosium doping samples possessed a weak connection in the bulk samples. Hence, this study is conducted to investigate the influences of rare earth elements (Ce, Dy) doping on the structural and superconducting properties in low density Bij 6Pbo 4Sr2Ca2Cu3 0 y superconductor. In this research, the influences of cerium and dysprosium doped low density Bi| 6Pbo 4Sr2Ca2Cu3 0 y superconductor were studied based on the best level of low density and sintering time, furthermore, the technique of mixing the superconducting samples with sucrose was used to prepare the low density rare earth elements (Ce, Dy) doped Bi| 6Pbo 4Sr2Ca2Cu3 0 y superconductor. The optimum level of sucrose was found at 0.050 g mixed with 1.950 g of Bi(Pb)SrCaCuO powder while the critical current density, Jc of high density (standard sample) and optimum lowdensity was measured to be 3.746 A/cm 2 and 5.405 A/cm 2 , respectively at 77 K under zero magnetic field. Furthermore, the optimal sintering time of the samples Bii 6Pbo 4Sr2Ca2Cu3 0 v system was found at 850°C for 72 hours. The best Jc achieved in high density and optimal low density samples were 7.547 A/cm 2 and 8.333 A/cm 2 respectively at 77 K under zero magnetic fields. However, it was found that both doped Ce and Dy at Ca site indicated deteriorations on the superconducting properties when compared with the undoped samples. The doping samples exhibited the
increased values of 7c and Jc towards the optimum concentration and decreased after the further increase of Ce and Dy dopants
Investigation of daylighting performance inside building due to light pipes of different designs / Robaiah Mamat
Get PDFMalaysia is blessed with plenty of sunlight. Fully utilize of this great natural resource would significantly reduce the total electric energy consumption in buildings. Using light pipe for example, to introduce natural light in the occupied space is said to give a lot of advantages. Its small cross sectional area of opening allows less heat to enter the building. In addition, light pipe is also applicable for deep interior spaces, where having windows is an impossible option. This study was conducted to investigate the performance of five different designs of light pipes models. The models were built using a highly reflective material and were tested in a room model under a solar simulator. The whole experiment was divided to two parts. The first part covers the investigation on the intensity of the transmitted daylight when the light pipe models were placed at the center of the roof. The result indicates that cylindrical design performs the best in terms of the average illuminance of the transmitted daylight as well as the distribution of the light. In the second part, further investigation was carried out by placing the light pipes at one corner of the room. This involves only two designs which can be fixed nicely to the corner of the walls. It was found that having only one unit of light pipe of such design is not sufficient in bringing in daylight into the interior "space. However, prediction based on the real measurement data shows that certain light pipe designs that can be fixed well to the corners have great potential to replace artificial light during daytime if more than one unit is used
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
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
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