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Semarang, Indonesia

Susilawati,University of Semarang
2014 International Conference on Physics, ICP 2014 | Year: 2014

This research project is based on vocational skills in physics teaching materials for vocational high school students. Vocational skill-based project was developed to improve the skills of vocational students. The series of student activities, scientific activities and assignments designed so as to help students mastering the skills for vocational school. In this study, the research object is the light vehicle engineering and voltage electrical installation techniques. The series of scientific activities and assignment of students was tested in a group of students majoring in engineering light vehicle and a group of students majoring in electrical voltage installation techniques. This research was carried out by quantitative descriptive approach. Observations made during the learning skills of the students. Mastery of the skills of students before and after participating in a series of scientific activities and assignments will be compared. The discussion will be reviewed at each condition and the symptoms that arise during the learning process. The results of this study showed that each of the research subjects experienced an increase in vocational skills, which was showed from assessment of student performance. The results of performance evaluation conducted tests and observation. Performance capabilities after a series of scientific activities and assignments is higher. Based on these results, project-based vocational skills can be recommended to improve the skills of vocational students are ready to work for technology. © 2014. The authors - Published by Atlantis Press.

Riyadi S.,University of Semarang
ICITACEE 2015 - 2nd International Conference on Information Technology, Computer, and Electrical Engineering: Green Technology Strengthening in Information Technology, Electrical and Computer Engineering Implementation, Proceedings | Year: 2016

Stand-alone photovoltaic systems are still required in locations where electricity is unavailable. They can provide electric energy for pumping systems, lightings, etc. This paper presents a design of a photovoltaic powered converter to provide regulated AC voltage. The system consists of a buck chopper and an inverter. The chopper acts as a Maximum Power Point Tracker to optimize the battery charging. The inverter used in the proposed system is operated as a controlled voltage source to force its output voltage tracks the reference. The controllers are implemented by dsPICs. Simulation and experimental results show the effectiveness of the proposed system with simple control scheme. Sinusoidal voltage can be generated by the inverter based on look-up table method. The power equilibrium is also achieved. © 2015 IEEE.

Riyadi S.,University of Semarang
2014 1st International Conference on Information Technology, Computer, and Electrical Engineering: Green Technology and Its Applications for a Better Future, ICITACEE 2014 - Proceedings | Year: 2015

A photovoltaic (PV)-Grid System integrates electric energy generated by PV modules and a grid. A Maximum Power Point Tracker (MPPT) is required due to PV characteristic. It will force the PV modules produce maximum power in the DC voltage. It is needed an inverter to convert DC into AC voltage and to match the grid voltage. A standard inverter topology used in active filtering is functioned to inject harmonic and reactive power components but it must be able to transmit active power component in PV-Grid System. Instantaneous power concept is often used to control an active power filter due to its simplicity. In this paper, a control method for a three-phase three-legs inverter is proposed. This is based on inverse Clarke Transformation. The inverter is implemented by Voltage Source Inverter (VSI) that is operated as a controlled current source by using a current controller. Inverter output currents will be compared to references produced by inverse Clarke Transformation. To achieve power equilibrium, the voltage of the DC-link is kept constant. The obtained results have proven that all the power generated by the PV modules can be transmitted into the grid. © 2014 IEEE.

Suseno H.,National Nuclear Energy Agency | Wahono I.B.,Agency for Assessment and Application of Technology | Muslim,University of Semarang
Marine Pollution Bulletin | Year: 2015

As data on anthropogenic radionuclide concentrations (i.e., 134Cs and 137Cs) in Indonesian marine environments including the Indian Ocean are scarce, offshore monitoring has been performed in the West Sumatra and South Java Seas. The activity concentration of 137Cs ranges from below minimum detectable activity (MDA) to 0.13Bqm-3 in the surface seawater of the South Java Sea and from lower than MDA to 0.28Bqm-3 in the surface seawater of the West Sumatra Sea. The concentrations of 137Cs in the surface seawater of the West Sumatra and South Java Seas are lower than the estimation of 137Cs concentration in the subsurface waters owing to the input of the North Pacific Ocean via the Indonesian Throughflow (ITF). The concentrations of 134Cs in the sampling locations were lower than MDA. These results have indicated that these Indonesian marine waters have not yet been influenced by the Fukushima radioactive release. © 2015 Elsevier Ltd.

Setiawan F.B.,University of Semarang
2014 1st International Conference on Information Technology, Computer, and Electrical Engineering: Green Technology and Its Applications for a Better Future, ICITACEE 2014 - Proceedings | Year: 2015

Speech signal can be modeled by sinusoidal model. On the sinusoidal model, there are many kinds for representing the signal. One of model is Segmental Sinusoidal model. The segmental sinusoidal model is an approximation method based on sinusoidal model for speech signal, especially for periodic detection. The periodic signal can be decomposed by infinite sinusoidal signal with combination of amplitude, frequency and phase. After the signal is decomposed, parameter will be quantized. The proposed quantization method in this paper is sampling signal on big part between minimum and maximum part over observation block. Some parameters of speech signal are detected. The useful parameters are peaks and period between consecutive peaks. Period information obtained from this quantization tends to different than the original, In this paper, we show the experimental results that there are many differences between period information on encoder side with the decoder side. It caused by quantization error on period information and quantization error on the codebook design. Effect of differences is degradation of signal quality, especially on frequency signal accuracy. On this paper, deviation of the reconstructed signal from original signal will be evaluated. Deviation from the original signals means that some error occur on period quantization. © 2014 IEEE.

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