1,720,958 research outputs found
PRODUKSI BIODIESEL DARI MINYAK JELANTAH MENGGUNAKAN KATALIS KALSIUM OKSIDA
No full textThe transesterification reaction has performed to convert waste cooking oils into biodiesel with assistant of heterogen catalyst of calcium oxide using reactor in a laboratory . The reaction was performed in two stages that is the esterification followed transesterification reaction. The aim of research is to study the effect of temperature and time reaction on viscosity and biodiesel yield. The results showed that obtained biodiesel had viscosity value in accordance with SNI 04-7182-2006 about diesel-fuel viscosity. At lower temperature (40, 45, and 50°C), the longer reaction time could lead to the increasing of biodiesel yield. Meanwhile, at higher temperature reaction (55°C and 60°C) the longer reaction time could reduce biodiesel yield. The highest biodiesel yield was obtained at following reaction condition: temperature reaction 50°C, 6 hours reaction time, ratio oil:MeOH = 1:48 molar ratio, % wt CaO = 8% to weight of waste cooking oil
PENGARUH MICROWAVE HEATING TERHADAP KUALITAS MINYAK DEDAK PADI
No full textRice bran oil as an alternative edible oil is promising to be developed. However, the presence of lipaze enzym which hydrolyze actively trigliceride into free fatty acid results rice bran quality can not be controlled and tend to degrade. Stabilization proccesswas needed to overcome this isue. Stabilization with microwave heating has been carried out to study the effect of stabilization toward the quality of rice bran oil. The results showed that the highest percentage of oil mass 7.67% was obtained at mediumpower (power 2), stabilization time 1 minute and the extraction waiting time for 0 week. Meanwhile, the levels of free fatty acids tended to be constant when the proccess was carried out at power 3 (high power) for all stabilization times. Microwave heating was effective enough to reduce the lipase enzyme in rice bran so as free fatty acid content did not increase significantly.
Keywords: Microwave Heating, Rice Bran Oil, Stabilization
TRANSESTERIFIKASI MINYAK DEDAK PADI SECARA IN-SITU DENGAN BANTUAN GELOMBANG MIKRO
No full textRice bran as rice milling waste is very promising to be used as raw material of oil producer such as biodiesel oil. The production process with the assistant of microwaves has been studied in this research. The production process was carried out in-situ where the extraction process of rice bran oil and the biodiesel formation reaction occur simultaneously in microwave radiation. Rice bran was obtained from Lamongan area with IR 64 type. The reaction was carried out in microwaves that had been modified by variation of operating conditions including reaction times (10, 30 and 50 min) and weight ratio of rice bran to methanol (1:4, 1:8, 1:12, 1:16 and 1:20). The results obtained are then analyzed by product yield and free fatty acid content. The optimum condition is obtained when the highest yield of the product with the lowest free fatty acid. The results showed that the optimum condition was obtained at reaction time of 30 minutes with the ratio of rice bran: methanol at 1:12
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
In-situ Biodiesel and Sugar Production From Rice Bran Under Subcritical Condition
Get PDFAn integrated method of producing biodiesel and sugar using subcritical water and methanol has been employed as a
potential way to reduce the high cost of single biofuel production from rice bran. The effects of temperature, methanol to water
ratio and reaction time on the biodiesel yield and purity, and the concentration of sugar in hydrolysate were investigated
systematically. Biodiesel with yield and purity of 65.21%and 73.53%, respectively, was obtained from rice bran with initial free
fatty acid (FFA) content of 37.64% under the following conditions: T= 200 oC, P= 4.0 MPa (using CO2 as pressurizing gas), ratio
of rice bran/water/methanol of 1/2/6 (g/mL/mL), and 3 h of reaction time. FFAs level was reduced to 10.00% with crude
biodiesel recovery of 88.69%. However, the highest biodiesel yield (67.39%) and crude biodiesel recovery (100.00%) were
obtained by decreasing the amount of methanol so that the ratio of rice bran/water/methanol became 1/4/4, g/mL/mL. In addition,
the highest sugar concentration of 0.98 g/L was obtained at 180 oC and 4.0 MPa with ratio of rice bran/water/methanol of 1/4/4
(g/mL/mL) and reaction time of 3 h. Since no catalyst was employed and the biodiesel and reducing sugar were produced directly
from rice bran with high water and FFA contents, the process was simple and environmentally friendly, which would make the
production of biofuel more economical and sustainable
- …
