Diawati C.,Lampung University
AIP Conference Proceedings | Year: 2016
The enthalpy concept and its change were introduced to describe the forms of internal energy transfer in chemical reactions. Likewise, the concepts of exothermic and endothermic reactions introduced as a consequence of heat transfer form. In the heat measurement process at constant pressure, work is often ignored. The exothermic or endothermic reactions, usually only based on the increase or decrease of the reaction temperature, without associated with the internal energy. Depictions of enthalpy and its change assumed closely related to students' problem-solving ability. Therefore, the study to describe pre-service chemistry teacher student's conceptions and problem-solving ability on topic chemical thermodynamics has been done. This research was a case study of chemical education course in Provinsi Lampung. The subjects of this study were 42 students who attend the chemical thermodynamics course. Questions about exothermic and endothermic reactions, enthalpy and its change, as well as internal energy and its change were given in the form of an essay exam questions. Answers related to conception qualitatively categorized, while problem solving answers were scored and assessed. The results showed that, in general, students were having problems in enthalpy and describe the changes in the form of heat and work. The highest value of problem solving ability obtained 26.67 from the maximum value of 100. The lowest value was 0, and the average value was 14.73. These results show that the problem-solving ability of pre-service chemistry teacher students was low. The results provide insight to researchers, and educators to develop learning or lab work on this concept. © 2016 AIP Publishing LLC.
Amrizal N.,Lampung University |
Amrizal N.,University of Lleida |
Chemisana D.,University of Lleida |
Rosell J.I.,University of Lleida
Applied Energy | Year: 2013
A hybrid photovoltaic/thermal transient model has been developed and validated experimentally. The methodology extends the quasi-dynamic thermal model stated in the EN 12975 in order to involve the electrical performance and consider the dynamic behavior minimizing constraints when characterizing the collector. A backward moving average filtering procedure has been applied to improve the model response for variable working conditions. Concerning the electrical part, the model includes the thermal and radiation dependences in its variables. The results revealed that the characteristic parameters included in the model agree reasonably well with the experimental values obtained from the standard steady-state and IV characteristic curve measurements. After a calibration process, the model is a suitable tool to predict the thermal and electrical performance of a hybrid solar collector, for a specific weather data set. © 2012 Elsevier Ltd.
Asmiati,Lampung University |
Baskoro E.T.,Bandung Institute of Technology
AIP Conference Proceedings | Year: 2012
Let G be a connected graph G. Let c be a k-coloring of V(G) which induces an ordered partition Π = S 1,S 2,.,S k of V(G), where S i is the set of vertices receiving color i. The color code c Π(ν) of vertex ν is the ordered k-tuple (d(ν,S 1), d(ν, S 2),., d(ν, S k)), where d(ν, S i) = min d(ν, x)|x ∈ S i, for 1 ≤ i ≤ k. If the color codes of all vertices are different, then c is called a locating-coloring of G. The locating-chromatic number of G, denoted by χ L(G) is the smallest k such that G has a locating k-coloring. In this paper, we investigate graphs with locating-chromatic number 3. In particular, we determine all maximal graphs having cycles (in terms of the number of edges) with locating-chromatic number 3. From this result, we then characterize all graphs on n vertices containing cycles with locating-chromatic number 3. © 2012 American Institute of Physics.
Sukmana I.,University of Technology Malaysia |
Sukmana I.,Lampung University
The Scientific World Journal | Year: 2012
The guidance of endothelial cell organization into a capillary network has been a long-standing challenge in tissue engineering. Some research efforts have been made to develop methods to promote capillary networks inside engineered tissue constructs. Capillary and vascular networks that would mimic blood microvessel function can be used to subsequently facilitate oxygen and nutrient transfer as well as waste removal. Vascularization of engineering tissue construct is one of the most favorable strategies to overpass nutrient and oxygen supply limitation, which is often the major hurdle in developing thick and complex tissue and artificial organ. This paper addresses recent advances and future challenges in developing three-dimensional culture systems to promote tissue construct vascularization allowing mimicking blood microvessel development and function encountered in vivo. Bioreactors systems that have been used to create fully vascularized functional tissue constructs will also be outlined. © Copyright 2012 Irza Sukmana.
Sukmana I.,University of Technology Malaysia |
Sukmana I.,Lampung University
Journal of Artificial Organs | Year: 2012
Tissue engineering seeks strategies to design polymeric scaffolds that allow high-cell-density cultures with signaling molecules and suitable vascular supply. One major obstacle in tissue engineering is the inability to create thick engineered-tissue constructs. A pre-vascularized tissue scaffold appears to be the most favorable approach to avoid nutrient and oxygen supply limitations as well as to allow waste removal, factors that are often hurdles in developing thick engineered tissues. Vascularization can be achieved using strategies in which cells are cultured in bioactive polymer scaffolds that can mimic extracellular matrix environments. This review addresses recent advances and future challenges in developing and using bioactive polymer scaffolds to promote tissue construct vascularization. © The Japanese Society for Artificial Organs 2012.
Samosir A.S.,Lampung University |
Samosir A.S.,University of Technology Malaysia |
Yatim A.H.M.,University of Technology Malaysia
IEEE Transactions on Industrial Electronics | Year: 2010
An electric vehicle powered by fuel cells (FCs) gives far more promising performance. An FC is a clean energy source and has a high energy-storage capability. However, an FC has a slow dynamic response. A secondary power source is needed during start-up and transient conditions. An ultracapacitor can be used as a secondary power source to improve the performance and efficiency of the overall system. Several methods have been devised to connect an energy-storage device to an FC. This paper presents a converter system for connecting an ultracapacitor as secondary energy storage to an FC electric-vehicle system. A bidirectional dcdc converter is used for interfacing ultracapacitor energy storage to an FC system. The controller of the converter system was designed and implemented based on dynamic evolution control. The performance of the proposed dynamic evolution control is tested through simulation and experiment. Simulation and experimental results show that the proposed techniques are suitable for controlling bidirectional dcdc converters. © 2010 IEEE.
Suharso,Lampung University |
Buhani,Lampung University |
Bahri S.,Lampung University |
Endaryanto T.,Lampung University
Desalination | Year: 2011
The investigation of Gambier extracts (Uncaria gambier Roxb leaves) as an inhibitor of calcium carbonate scale formation has been carried out using the bottle-roller batch method with the concentration of a growth solution ranging from 0.1 to 0.6M and at the temperature of 80°C. The data obtained shows that Gambier extracts inhibit the formation of calcium carbonate scale at the various concentrations of the growth solution. The ability of Gambier extracts as an inhibitor of the formation of calcium carbonate scale is around 40-100% in inhibiting the growth rate of CaCO3 scale. This ability depends on the concentration of Gambier extracts added into the growth solution and the concentration of the growth solution as a growth media of CaCO3 seed crystals. © 2010 Elsevier B.V.
Hermida L.,Universiti Sains Malaysia |
Hermida L.,Lampung University |
Abdullah A.Z.,Universiti Sains Malaysia |
Mohamed A.R.,Universiti Sains Malaysia
Renewable and Sustainable Energy Reviews | Year: 2015
Deoxygenation process of fatty acid as a renewable resource to produce diesel-like hydrocarbons is one of the alternatives to address drastic shortage of crude oil-based fuels in the near future. Catalytic deoxygenation process of fatty acid is getting attention from both academia and industry. Researchers have tried different techniques in the fatty acid deoxygenation to enhance the production of diesel-like hydrocarbons. This review paper elucidates the influence of tmain operating conditions towards achieving optimum yield and selectivity of desired products. The reaction pathways, the reaction kinetics as well as recent progress in deoxygenation of fatty acid for production of diesel-like hydrocarbons are also reviewed. © 2014 Elsevier Ltd. All rights reserved.
Kartika T.,Lampung University
Social Sciences (Pakistan) | Year: 2016
Indonesia is a developing country, it also the country with the largest population in Southeast Asia. Most female population the use of cosmetics in everyday life. Unfortunately, many dangerous cosmetic products on the market. In general, dangarous cosmetic products dominated by the dye content is prohibited (red K3, rhodamine), contamination of heavy metals Pb and whitening (mercury). Selling whitening cosmetic products can not be separated from the public perception that beautiful is white. NA-DFC. The National of Drug and Food Agency has attempted to tackle the circulation of these products in the market. This study discusses: use of cosmetics female Indonesian nation; Triple M theory; some research on dangarous cosmetics. The results of this discussion is the mass media (television) take part in instilling the perception that a beautiful woman is white skin, smooth, slim as an advertising model on the face whitening products. Study Triple M theory explains that the mass media (television and web pages BPOM/NA-DFC), social (relationships groups or individuals) and culture (values, habits, perception) is a continuous unitary spawned use dangarous cosmetic products as well overcome. © Medwell Journals, 2016.
ICREM7 2015 - Proceedings of the 7th International Conference on Research and Education in Mathematics: Empowering Mathematical Sciences through Research and Education | Year: 2015
This paper is concerned with a mathematical derivation of the nonlinear time-discrete Technology Emission Means (TEM) model that discuss its behavior from the perspective of discrete dynamical systems. Nonlinear time-discrete dynamics tends to chaotic behavior. The addition of a control parameter into the dynamics of this model has led to new results in the field of time-discrete control systems. In this paper, we added another control parameter into the TEM model in the form of regulation. More ever we discuss stability theory of the TEM model, numerical solutions and compare their behavior before and after the addition of the regulatory control parameter. Finally, we obtained that by adding regulatory control parameter more stable than before. © 2015 IEEE.