Muhammadiyah University of Surakarta
Surakarta, Indonesia

Muhammadiyah University of Surakarta is one of 164 Universities of Muhammadiyah and one of the 1890 Private Higher Educational institutions in Indonesia. Charity business education is determined to create a campus that promotes "Scientific and Islamic Discourse" to foster an Islamic culture that will instill in its students, knowledge and skills based on Islamic values. Wikipedia.

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Ulinuha A.,Muhammadiyah University of Surakarta
Proceeding - 2016 International Seminar on Intelligent Technology and Its Application, ISITIA 2016: Recent Trends in Intelligent Computational Technologies for Sustainable Energy | Year: 2016

The extensive and ever increasing application of nonlinear loads has introduced a distortion in power system voltage. The nonlinear v-i relation of the devices leads to the existence of higher frequency components of voltage/current causing system voltage no longer sinusoidal. The higher frequency components of current may be blocked using proper harmonic filters. However the location of filters should be carefully decided. Since the distorted currents may inject and flow over the system the assessment of filter locations is necessary to find the best locations. The impact of filter locations on harmonic suppression is evaluated using harmonic flow analysis. For this purposes, a Decoupled Harmonic Power Flow (DHPF) is developed and used in this study. The proposed scheme is implemented on a 30-bus distribution system to investigate the relation between filter locations and distortion mitigation. © 2016 IEEE.

Egerton T.A.,Newcastle University | Purnama H.,Newcastle University | Purnama H.,Muhammadiyah University of Surakarta
Dyes and Pigments | Year: 2014

A comparison of UV-C initiated decolourations of the anionic azo-dye Reactive Orange 16 by H2O2, by anatase TiO2 (PC500), and by H2O2/TiO2 is reported. The decolouration rates induced by H2O2, by TiO2 and by H2O2/TiO2, were compared in order to determine whether H2O2/TiO2 was more beneficial than either H2O2 or TiO2 alone. UV-C photolyses H2O2 to form hydroxyl radicals. UV-C can also initiate hydroxyl radical formation at the surface of TiO2, and in this study the photocatalytic conditions were chosen to enhance hydroxyl radical formation. In both cases the hydroxyl radicals lead to decolouration of the azo-dye Reactive Orange 16. Decolouration by irradiation of H2O 2/TiO2 was ∼5 times faster than by the TiO2 photocatalyzed reaction but slower than that caused by irradiation of H 2O2 alone. Thus, the relative order of decolouration rates is: UV-C/TiO2 < UV-C/TiO2/H2O2 < UV-C/H2O2. Estimates of the absorption of UV by both H2O2 and H2O2/Reactive Orange 16 solutions are used to show that this order is a consequence of the photonic efficiency of H2O2 photolysis being ten to a hundred times larger than the photonic efficiency of hydroxyl radical generation at the surface of TiO2. © 2013 Published by Elsevier Ltd.

Widayatno T.,Muhammadiyah University of Surakarta
AIP Conference Proceedings | Year: 2015

Electrodeposition of nickel onto copper in a system of low Ni2+ concentration and at a narrow interelectrode gap has been carried out. This electrochemical system was required for maskless pattern transfer through electroplating (Enface technique). Kinetics of Electrochemical reaction of Nickel is relatively slow, where such electrochemical system has never been used in this technology. Study on the kinetics of the electrochemical reaction of nickel in such system is essential due to the fact that the quality of an electrodeposited nickel is affected by kinetics. Analytical and graphical methods were utilised to determine kinetic parameters. The kinetic model was approximated by Butler-Volmer and j-η equation. Kinetic parameters such as exchange current density (j0) and charge transfer coefficient (α) were also graphically determined using the plot of η vs. log|j| known as Tafel plot. The polarisation data for an unstirred 0.19 M nickel sulfamate solution at 0.5?mV/s scan rate and RDE system was used. The results indicate that both methods are fairly accurate. For the analytical, the Tafel slope, the exchange current density, and charge transfer coefficient were found to be 149?mV/dec, 1.60 × 10-4 mA/cm2, and 0.39 respectively, whilst for the graphical method were 159?mV/dec, 3.16 × 10-4 mA/cm2, and 0.37. The kinetics parameters in this current study were also compared to those in literature. Significant differences were observed which might be due to the effect of composition and concentration of the electrolytes, operating temperature, and pH leading to the different reaction mechanism. However, the results obtained in this work are in the range of acceptable values. These kinetic parameters will then be used in further study of nickel deposition by modelling and simulation. © 2015 AIP Publishing LLC.

Hidayati N.,Muhammadiyah University of Surakarta | Scott K.,Northumbria University
Bulletin of Chemical Reaction Engineering and Catalysis | Year: 2016

Even though platinum is known as an active electro-catalyst for ethanol oxidation at low temperatures (< 100 oC), choosing the electrode material for ethanol electro-oxidation is a crucial issue. It is due to its property which easily poisoned by a strong adsorbed species such as CO. PtSn-based electro-catalysts have been identified as better catalysts for ethanol electro-oxidation. The third material is supposed to improve binary catalysts performance. This work presents a study of the ethanol electro-oxidation on carbon supported Pt-Sn and Pt-Sn-Ni catalysts. These catalysts were prepared by alcohol reduction. Nano-particles with diameters between 2.5-5.0 nm were obtained. The peak of (220) crystalline face centred cubic (fcc) Pt phase for PtSn and PtSnNi alloys was repositioned due to the presence of Sn and/or Ni in the alloy. Furthermore, the modification of Pt with Sn and SnNi improved ethanol and CO electro-oxidation. Copyright © 2016 BCREC GROUP. All rights reserved.

Ulinuha A.,Muhammadiyah University of Surakarta | Masoum M.A.S.,Curtin University Australia | Islam S.,Curtin University Australia
IET Generation, Transmission and Distribution | Year: 2011

A hybrid genetic-fuzzy algorithm (GA-Fuzzy) is proposed for optimal volt/var/total harmonic distortion (THD) control in distorted distribution systems serving non-linear loads. Load interval division (over a 24 h period) and optimal scheduling of load tap changer and switched shunt capacitors for simultaneously minimising energy losses and improving the power quality (as recommended by the IEEE 519 and IEC 61000 standards) are performed using GAs with fuzzy reasoning. The non-linear load flow is solved using a decoupled harmonic power flow algorithm. The integration of fuzzy rules and GA enables the approach to maintain the promising chromosomes and offer further improvement of the near-global solution. The IEEE 30-bus and 123-bus distribution systems with a number of harmonic generating loads are selected for the analyses. Simulation results using GA and GA-Fuzzy optimisation approaches are presented and compared for sinusoidal and non-sinusoidal treatments of the systems to demonstrate the advantages of the proposed hybrid approach. © 2011 The Institution of Engineering and Technology.

Supriyono,Muhammadiyah University of Surakarta
ARPN Journal of Engineering and Applied Sciences | Year: 2016

In this paper a formulation of boundary element method for shear deformable plate theory with material nonlinearity is presented. The material is assumed to undergo small strains. The von Mises criterion is used to evaluate the plastic zone and elastic perfectly plastic material behaviour is assumed. An initial stress formulation is used to formulate the boundary integral equations. Not only the plastic strain due to bending but also the plastic strains due to membrane are considered. The domain integral due to material nonlinearity is evaluated using a cell discretization technique. A total incremental method is applied instead of an incremental and iterative procedure, to solve the nonlinear boundary integral equations. Numerical examples are presented to demonstrate the validity and the accuracy of the formulation. © 2006-2016 Asian Research Publishing Network (ARPN).

Widayatno T.,Muhammadiyah University of Surakarta
ARPN Journal of Engineering and Applied Sciences | Year: 2016

Thickness and morphology of electrodeposited coating is crucial in every application of protective finish to ensure high quality and performance is achieved. How a deposited metal is distributed across the cathode surface is greatly affected by current density distribution. To calculate current density distribution prior to the design of electrochemical system is essential in order to optimize the uniformity. The effect of cell geometry and kinetics on current density distribution in nickel electrodeposition from low electrolyte concentration and narrow interelectrode gap has been investigated. This electrochemical system was required for nickel pattern transfer using Enface technology. The modelling and simulation was carried out by solving Laplace's equation in the potential model theory considering appropriate boundary conditions using the Boundary Element Method. The simulation was accomplished by using software of Elsy (ELSYCA NV). The results show that the current density distribution using 2D and axy-symmetrical system was identical for all electrode sizes. However, current density at the electrode edge in the axy-symmetrical model was higher by around 19 % which might be due to the extra space around the electrode. Thus, 2D configuration was sufficient to represent the actual reactor geometry for the experimentation. In a parallel plane electrode configuration, the current density significantly increases at the edge of the cathode. The current density was uniform in the range of 0.08< x/L (normalized length) < 0.92 which was over 80% of the surface area. Therefore, the patterns should be located at the middle of the anode for ensuring a uniform thickness of deposited nickel pattern was achieved. © 2006-2016 Asian Research Publishing Network (ARPN).

Solikin M.,Muhammadiyah University of Surakarta
Materials Science Forum | Year: 2016

This paper presents a research to produce high strength concrete incorporated with fly ash as cement replacement up to 50% (high volume fly ash concrete) by using local material. The research is conducted by testing the strength development of high volume fly ash concrete at the age of 14 days, 28 days and 56 days. As a control mix, the compressive strength of Ordinary Portland Cement (OPC) concrete without fly ash is used. Both concrete mixtures use low w/c. consequently, they lead to the use of 1% superplasticizer to reach sufficient workability in the process of casting. The specimens are concrete cubes with the dimension of 15 cm x15 cm x 15 cm. The totals of 24 cubes of HVFA concrete and OPC concrete are used as specimens of testing. The compressive strength design of concrete is 45 MPa and the slump design is ± 10 cm. The result shows that the compressive strengths of OPC concrete at the age of 14 days, 28 days, and 56 days are 38 MPa, 40 MPa, and 42 MPa. Whereas the compressive strength of HVFA concrete in the same age of immersing sequence are 29 MPa, 39 MPa, and 42 MPa. The result indicates that HVFA concrete can reach the similar compressive strength as that of normal concrete especially at the age of 56 days by deploying low water cement ratio. © 2016 Trans Tech Publications, Switzerland.

Sarjito S.,Muhammadiyah University of Surakarta
Applied Mechanics and Materials | Year: 2013

Downdraft evaporative cooling systems can be used for the thermal management of inside spaces in hot dry environments. There may be scope for improvement of such systems. The work described here is a study aimed at validating the Computational Fluids Dynamics (CFD) method using experimental data available from a prototype multi-stage system which existed at Ben-Gurion University. A detailed model of the prototype device has been developed. Initial CFD work has focused on establishing the relationship between ambient wind speed and the downdraft flow rate and comparing the result with the existing experimental data. Initial results are consistent and encouraging. Detailed flow features not evident from the experiments are revealed. Further CFD work to model the prototype performance with water spray evaporation is described briefly. © (2013) Trans Tech Publications, Switzerland.

Ulinuha A.,Muhammadiyah University of Surakarta
ARPN Journal of Engineering and Applied Sciences | Year: 2016

Distribution system is a part of electrical system that suffering from a number of problems, such as load variation, voltage fluctuation, and harmonic distortion. Harmonic distortion is one of the concerns recently taking more attention since it may cause losses amplification, rms voltage increment, and, the most dangerous effect is, equipment destruction if resonance frequency occurs. The extensive use of devices generating harmonic frequencies is the main reason of the problem. The nonlinear v-i characteristic of the devices may result in distortion of system voltage that should be prevented not to spread and further deteriorate the system. For this purpose, harmonic filter is commonly installed in the system. Distribution system normally includes a number of shunt capacitors for voltage improvement and losses minimization. However, the capacitors may also amplify the distortion. In this paper, the location and size of harmonic filters is determined using Genetic Algorithm. The aims are to improve the voltage and minimize the losses while mitigating the distortion. The implementation on the IEEE 18-bus system indicates simultaneous system enhancements including voltage improvement, losses reduction, and harmonic mitigation with minimum system modification and cost requirement. © 2006-2016 Asian Research Publishing Network (ARPN).

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