Syamsiro M.,Janabadra University |
Saptoadi H.,Gadjah Mada University |
Tambunan B.H.,State University of Medan |
Pambudi N.A.,State University of Semarang
Energy for Sustainable Development | Year: 2012
Indonesia is the third largest producer of cocoa bean in the world. One of the residues produced after removal of the cocoa bean from the fruit is cocoa pod husk (CPH). The objective of this work was to assess the use of CPH as a renewable energy source. CPH was sun-dried, crushed, and screened to obtain a particle size of less than 1. mm. Five grams mixture of CPH and binder in the proportion of 70% and 30% by weight respectively was pelletized and dried at 50 °C for 5. hours. Carbonization was performed at 400 °C for 2. hours. The results show that CPH has a high heating value of 17.0. MJ/kg. The air flow rate and fuel composition significantly affected the burning time and CO emission factor. The increase of carbonized CPH portion in the fuel increased the burning time of the pellet. The increase of air flow rate and carbonized CPH portion also increased the emission factor of CO. © 2011 International Energy Initiative.
Simanjuntak J.P.,Universiti Sains Malaysia |
Simanjuntak J.P.,State University of Medan |
Zainal Z.A.,Universiti Sains Malaysia
Biomass and Bioenergy | Year: 2015
This study aims to improve the heating value (HV) of gas produced during the gasification of sawdust using a new type of air-blown gasifier based on a two-compartment cylindrical fluidized bed. The gasification process is based on an internally circulating aerated fluidized bed (ICAFB) and consists of two individual zones; a gasification zone in the annulus and combustion zone in the draft tube. The annulus and draft tube are connected via orifices at the lower section of the draft tube wall to enable the solids to move from the annulus to the draft tube. Char, gasified residue, together with hot bed material move to the draft tube and combust to produce heat. Fluidization ratio (RQ) which is the ratio of air flow rate in the annulus (Qan) to the air flow rate in the draft tube (Qdt) together with equivalence ratio (ER) were used to control the temperature of the gasifier. The effects of ER on the temperature system stabilization, composition, HV of producer gas (PG) and gasifier performance were presented. ER ranges from 0.148 to 0.203 were used in this study. PG compositions of 3.13%, 2.28%, 25.8%, 8.2% and 22.48% for H2, O2, CO, CH4 and CO2 respectively with a HV of about 6.96 MJ m-3 were obtained at an ER of 0.185 and temperature of about 866°C. Compared with previous air-blown fluidized bed biomass gasification results, the ICAFB gasifier is capable of producing producer gas with higher CO and CH4 fractions. © 2015 Elsevier Ltd.
Mustari E.,Bandung Institute of Technology |
Diningrat D.S.,State University of Medan |
Ratnasih R.,Bandung Institute of Technology |
Widiyanto S.M.,Bandung Institute of Technology
Journal of Plant Sciences | Year: 2016
Background: Teak (Tectona grandis Linn f.) is one of valuable timber species because of the beauty, strength and durability properties. Main problem in teak improvement program is reproductive biology, a low pollen viability, high embryo abortion, low pollination success and low fruit production. Investigation carried out at the teak improvement that flowering aspects is very important. Teak development program was facing difficulties due to the lack of information about the role of genes regulating flowering. APETALA2 (AP2) and APETALA3 (AP3) genes as member of the floral organ Identity. The role of teak flowering development predicted by up and down regulation of TgAP2 and TgAP3 genes. This study was conducted to determine the gene expression profile of TgAP2 and TgAP3 in the developmental stages of teak flowering. Materials and Methods: In this study, TgAP2 and TgAP3 genes in teak identified from NGS transcriptome data that is annotated with Solanum lycopersicum. The TgAP2 and TgAP3 genes activities on the several developmental stages of teak flowering tissues are done with QRT-PCR analysis using 18S RNA as gene reference. Results: The highest expression level of TgAP2 on the floral development stages of 4th lateral floral buds. The TgAP3 gene expression reached the highest level on the apical floral bud stage development. Vegetative shoot as control stages, TgAP2 gene expression level reached 9 times compared to the control and TgAP3 more than 12 times. The TgAP2 and TgAP3 genes expression profile has non-significant correlation on all floral development stages. Conclusion: The TgAP2 and TgAP3 genes expressed with different level in all stages of the teak flowering development. The TgAP2 and TgAP3 genes have non-significant correlation expression profile in role of teak floral development. These results indicate that the TgAP2 and TgAP3 expression profiles equivalent to the general pattern in the Arabidopsis model plant. © 2016 Eri Mustari et al.
Sirait T.M.,State University of Medan |
Derlina,State University of Medan
Proceedings of the 2015 International Conference on Technology, Informatics, Management, Engineering and Environment, TIME-E 2015 | Year: 2015
The objectives of this research was to analyze whether the problem based learning model has a better effect than the direct instructional model towards physics learning outcomes. It also aims at using the problem based learning model for analyzing the student learning activity in an experimental class. The populations used in this research are three classes of high school students in SMAN 2 Balige, Indonesia (Classes X1, X2, X3, A.Y. 2014/2015). The control sample was class X1 whereas the experimented class was class X3. The analysis of the experiment in this research was based on the quasi-experimental method with two groups were being used for pretest and posttest designs. The data were collected using learning outcomes of seven essay writing tests and the learning activities were observed using some predesigned observation sheet. The data were analyzed using the descriptive and inferential statistics of obtained from the t-test of independent samples. The test was done using a significance level of 0.05. The result of the test showed that both of the students' samples have normal distribution when the population was assumed to be homogeneous. The test showed that the problem based learning model provides better effects than the direct instructional model when used to assess the student learning outcomes in a dynamic electricity class. © 2015 IEEE.
Molliq R.Y.,State University of Medan |
Noorani M.S.M.,National University of Malaysia
International Journal of Computational Methods | Year: 2013
This paper presents a new reliable modification of the variational iteration method (MoVIM). An enlarged interval of convergence region of series solutions is obtained by inserting a nonzero auxiliary parameter (h) into the correction functional of variational iteration method. Approximate analytical solutions for some examples of nonlinear problems are obtained using variational iteration method. Comparison with the exact solution, Runge-Kutta method 4, and also another modified variational iteration method has shown that MoVIM is an accurate method for solving nonlinear problems. © 2013 World Scientific Publishing Company.
Ginting E.M.,State University of Medan |
Bukit N.,State University of Medan
Indonesian Journal of Chemistry | Year: 2015
This study investigated the use of the electrochemical method to prepare alumina (α -Al2O3) from aluminum metal. The α-Al2O3 precursor was calcined at 110 °C for six hours and then characterized using Fourier Transform Infrared (FTIR) spectroscopy, Particle Size Analysis (PSA), X-Ray Diffraction spectroscopy (XRD), and Scanning Electron Microscopy (SEM). To study transformation of the precursor into α-Al2O3, three samples were sintered at 400, 800, and 1200 °C, respectively and they were characterized. The most interesting result obtained was the transition of AlOOH and α -Al(OH)3 into γ-Al2O3 at low temperatures (400 to 800 °C), followed by transformation of γ-Al2O3 into α -Al2O3 at high temperature (1200 °C). The overall results obtained demonstrated that electrochemical method is a potential alternative for production of α-Al2O3, which can be achieved in practically pure phase at sintering temperature at 1200 °C. © 2015, Gadjah Mada University. All rights reserved.
Manullang B.,State University of Medan |
Kons M.M.S.,State University of Medan
ICETC 2010 - 2010 2nd International Conference on Education Technology and Computer | Year: 2010
The purpose of this study was to improve the quality of learning through the integration model of hard skill and soft skills in the courses. The methods used in this study was research and development of the Borg and Gall, which were done with the steps as follows: a preliminary survey was done to collect data on faculty understanding of soft skills and capabilities in the integration of soft skills learning, learning styles and how students learn and data issues faced by students. Data acquisition techniques performed through self-evaluation and discussion forums (focus group discussion) and the guidance of the group. Data obtained were descriptive analyzed for mapping learning profile done. From the results of survey analysis which were conducted preliminary planning integration model diagrams and phase components of courses, and guide the integration model of soft skills and hard skills would be tested in the study were limited. Feasibility level to test the model proposed the hypothesis presented in the form of the following research question: how did the integration model soft skills and hard skills courses provide opportunities to improve the quality of learning. This study was conducted at the State University of Medan for seven faculties in 2009 year. The results of this study indicated that the integration hard skill (content area of study) with the soft skills (personal skills, social skills, transcendence skills and learning skills) can build a good learning atmosphere and successfully improve student success in learning. For lecturers and students of the lecture gives a satisfactory result, happiness and dignity. The model which was built collaboratively between teachers, counselors, students, therefore could be build a holistic academic atmosphere in the faculty and the university. © 2010 IEEE.
Luthan P.L.A.,State University of Medan
IOP Conference Series: Materials Science and Engineering | Year: 2016
Mandailing is one of bataknesse ethnic in North Sumatera which belong to strong to hold the customs and traditions Mandailing culture which reflected in the parts of the traditional houses. However rapidly the construction modern house make possibility the traditional house which enriched with culture value will be extinct.This studyto identify the value of culture and architecture typology of traditional house in Mandailing Natal North Sumatera. A case study using phenomenology method that is recording and serving the phenomenon which found in field as evidence that include existing condition from building. The finding show that 1) religion system or reliance in the front of location election, ornamentation orientation, construction system and room arrangement, 2) kinship system in the front of room organization, room amount and the completeness, 3) live philosophy found in shape and room arrangement which can accomodate all activity, 4) leadership system in the front of ornamentation shape and the meaning, pillar shape, house size vertically, and 5) social system in the front of roof shape, the used of decoration style and room arrangement. Architecture typology of Mandailing house dug from the shape and the construction, room arrangement, and roof shape. © Published under licence by IOP Publishing Ltd.
Rangkuti Y.M.,State University of Medan |
Sinaga M.S.,State University of Medan |
Marpaung F.,State University of Medan |
Side S.,University of Indonesia
AIP Conference Proceedings | Year: 2014
In this work, Vaccination (V), Susceptible (S) Infected (I), and Recovered (R) (VSIR) model for transmission of Tuberculosis in North Sumatera is modified. An exposed class is adopted to VSIR model so called VSEIR to determine the probability of people who infectious before infected. This model is written in ordinary differential equation (ODEs) in five classes. Determination the equilibrium point and stability analysis of the model is discussed to determine the dynamic behaviour of systems. A simulation is also discussed to see the suitable model to North Sumatera data. The simulation of VSEIR model indicates Tuberculosis has not endemic in North Sumatera. © 2014 AIP Publishing LLC.
Marpaung F.,State University of Medan |
Rangkuti Y.M.,State University of Medan |
Sinaga M.S.,State University of Medan
AIP Conference Proceedings | Year: 2014
The optimally of singular control for SEIR model of Tuberculosis is analyzed. There are controls that correspond to time of the vaccination and treatment schedule. The optimally of singular control is obtained by differentiate a switching function of the model. The result shows that vaccination and treatment control are singular. © 2014 AIP Publishing LLC.