Time filter

Source Type

Nong Khaem, Thailand

Jaikla W.,King Mongkuts University of Technology Thonburi | Noppakarn A.,Thonburi University | Lawanwisut S.,Thepsatri Rajabhat University

New first order allpass filter (APF) in current mode, constructed from 2 CCCCTAs and grounded capacitor, is presented. The current gain and phase shift can be electronically/orthogonally controlled. Low input and high output impedances are achieved which make the circuit to be easily cascaded to the current-mode circuit without additional current buffers. The operation of the proposed filter has been verified through simulation results which confirm the theoretical analysis. The application example as current-mode quadrature oscillator with noninteractive current control for both of oscillation condition and oscillation frequency is included to show the usability of the proposed filter. Source

Po-Ngam S.,Thonburi University
2014 11th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, ECTI-CON 2014

In this paper, the simplified control of three-phase four-leg shunt active power filter for harmonics mitigation, load balancing and reactive power compensation is proposed. In order to calculate the harmonics, current imbalance and reactive power, the load currents are detected and transformed to dq0 variables. By using the low-pass filter, the fundamental active power current can be separated from the d-axis current. Therefore, the commanded active power filter currents are consist of d-axis harmonic currents, q-axis and 0-axis currents. These components are regulated by the PI controller with feedforward utility voltage via the four-leg space vector inverter. Moreover, the design guidelines of space vector phase-locked loop (PLL), current controllers and DC-bus voltage controller are also presented. Validity of the proposed control schemes is confirmed by the simulation. © 2014 IEEE. Source

Maneewan S.,Buriram Rajabhat University | Sreewirote B.,Thonburi University | Jaikla W.,Suan Sunandha Rajabhat University
Proceedings of 2011 IEEE International Conference on Vehicular Electronics and Safety, ICVES 2011

A current-mode quadrature oscillator using single current follower transconductance amplifier (CFTA) as active element is given. The oscillator has high output impedance, employs two grounded capacitors, single resistor and has electronic control on oscillation condition and on oscillation frequency. The proposed circuit is suitable for integrated circuit (IC) architecture. PSpice simulation result is included to demonstrate the practicality of the oscillator circuit. © 2011 IEEE. Source

Thipprakmas S.,Thonburi University | Boochakul U.,Thonburi University
International Journal of Precision Engineering and Manufacturing

In recent years, increased manufacturing precision of complicated U-shaped parts is required. Such parts are typically fabricated by the U-bending process. However, there is a lack of research on the asymmetrical U-bending process. This results in processing difficulty in the control of spring-back characteristics. Therefore, in this study, the spring-back characteristics in the asymmetrical Ubending process were clearly clarified and compared with those in the symmetrical U-bending process using the finite element method (FEM). Furthermore, the effects of bend angle and tool radius on the spring-back characteristics were also investigated. The results revealed that the asymmetry of the U-shaped parts resulted in changes in bending and reversed bending stress distribution as well as in the spring-back characteristics. Therefore, with asymmetrical bend angles or tool radii in a U-shaped part, the changes in bend angle and/or tool radius on one side resulted in different spring-back characteristics and the obtained bend angle on the other side compared with the symmetrical U-shaped parts. Laboratory experiments were performed to validate the accuracy of the FEM simulation results. Based on the bend angles and bending forces, the FEM simulations showed good agreement with the experiments in terms of both the bend angles and bending forces. © 2015, Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg. Source

Hasanbeigi A.,Bangkok Thonburi University | Menke C.,Bangkok Thonburi University | Menke C.,Trier University of Applied Sciences | Therdyothin A.,Thonburi University
Energy Policy

The cement industry is one of the largest energy-consuming industries in Thailand with high carbon dioxide (CO2) emissions. Using a bottom-up electricity Conservation Supply Curve (CSC) model, the cost effective and the total technical electricity-efficiency potential for the Thai cement industry in 2008 is estimated to be about 265 and 1697 gigawatt-hours (GWh) which account for 8% and 51% of the total electricity used in the cement industry in 2005, respectively. The fuel CSC model shows the cost-effective fuel-efficiency potential to be 17,214 terajoules (TJ) and the total technical fuel-efficiency potential equal to 21,202 TJ, accounting for 16% and 19% of the total fuel used in cement industry in 2005, respectively. The economic analysis in this paper shows how the information from the CSCs can be used to calculate the present value (PV) of net cost savings over a period of time taking into account the energy price escalation rate. The results from the policy scenario analysis show that the most effective and efficient policy scenario is the introduction of an energy-related CO2 tax for the cement industry under a voluntary agreement program. This scenario results in 16.9% primary energy-efficiency improvement over a 5-year implementation period. © 2009 Elsevier Ltd. All rights reserved. Source

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