9 Articles Published

1. APPLICATION OF MAGNETIC LEVITATION IN ACTIVE MECHANICAL SUSPENSION SYSTEMS

Authors: F. BELTRÁN-CARBAJAL , G. ALVAREZ , S. VILLANUEVA , Z. DAMIÁN

Abstract: Magnetic levitation has shown its potential in many engineering fields with promising future applications. This paper deals with the asymptotic tracking problem of desired reference position trajectories in an active mechanical suspension system using magnetic levitation foundations. A differential flatness-based output feedback controller is proposed for accomplishing this control objective using only position measurements. The electromagnetic circuit dynamics is considered for design of the control voltage to regulate the position of the mechanical system in accordance with the specified motion planning. A robust observer is also presented for real-time estimation of the unavailable signals of acceleration and velocity. The electric current is algebraically reconstructed through the estimated signals. The efficient performance of the proposed observer-control scheme is verified by computer simulation.

Keywords: Active mechanical suspension, Magnetic levitation, Differential flatness, Observer

Pages: 1 - 6 | DOI: 10.15224/978-981-07-7021-1-32

2. A DESIGN FOR CYCLIC TIME-TO-DIGITAL CONVERTER

Authors: CHUN-WEI LIN , SHENG FENG LIN

Abstract: The time-to-digital converter is a widely used device for measuring pulse width, jitter and timing characteristic of signal. In this paper, we present a cyclic time-to-digital converter based on the pulse-shrinking technique. Through utilizing the Schmitt trigger and design rules, the resolution of pulse-shrinking cell can be precisely adjusted by controlling the high and low threshold voltage of the transition. The proposed time-to-digital converter was implemented by TSMC 0.35μm 3.3V process and the simulation results show the resolution of circuit is very well that less than 20ps. In addition, within 4ns, the differential nonlinearity is less than 0.5LSB with respect to the resolution of 20ps.

Keywords: time-to-digital converter, pulse-shrinking element, Schmitt Trigge

Pages: 12 - 15 | DOI: 10.15224/978-981-07-7021-1-34

3. A DESIGN FOR CYCLIC TIME-TO-DIGITAL CONVERTER

Authors: CHUN-WEI LIN , SHENG FENG LIN

Abstract: The time-to-digital converter is a widely used device for measuring pulse width, jitter and timing characteristic of signal. In this paper, we present a cyclic time-to-digital converter based on the pulse-shrinking technique. Through utilizing the Schmitt trigger and design rules, the resolution of pulse-shrinking cell can be precisely adjusted by controlling the high and low threshold voltage of the transition. The proposed time-to-digital converter was implemented by TSMC 0.35μm 3.3V process and the simulation results show the resolution of circuit is very well that less than 20ps. In addition, within 4ns, the differential nonlinearity is less than 0.5LSB with respect to the resolution of 20ps.

Keywords: time-to-digital converter, pulse-shrinking element, Schmitt Trigge

Pages: 12 - 15 | DOI: 10.15224/978-981-07-7021-1-34

4. INFLUENCE OF POLE ARC OFFSET ON THE FIELD AND OUTPUT PARAMETERS OF BRUSHLESS DC MOTORS

Authors: ADEM DALCALI , ALI SAYGIN , CEMIL OCAK , OSMAN GURDAL, , SEDAT ALANTAR

Abstract: In this study, for optimization of pole arc, parametric approach method of a 16 W powered, high efficiency permanent magnet brushless DC motor (BLDC) which is used especially in rotary cryogenic coolers and other specific applications is discussed. In the study, for the magnets composing rotor poles, the effects of motor on electromagnetic field and output parameters are examined by changing parametrically the offset point of the pole arc. For new magnet geometries acquired by change of pole arc offset point, motor parameters such as magnetic flux distribution, output power, output torque, cogging torque and efficiency were obtained by using analytical and finite element analysis. Motor parameters and parametric solution method used as optimization technique are effectively introduced. Finally, effects of pole arc offset distances to fields and output parameters of the motor are simulated and represented graphically. The proposed machine has 18 slot, surface mounted 6-pole and inner ru

Keywords: BLDC, pole arc offset, cryogenic cooling, parametric approach

Pages: 16 - 20 | DOI: 10.15224/978-981-07-7021-1-35

5. SIMULATION OF TURBINE GOVERNING IN HYDRO POWER PLANTS

Authors: SUMIT KUMAR , O.P.RAHI , SANJEEV KUMAR GAGRAI

Abstract: Power system performance is affected by dynamic characteristics of hydraulic governor turbines during and following any disturbance, such as occurrence of a fault, loss of a transmission line or a rapid change of load. Accurate modelling of hydraulic system is essential to characterize and diagnose the system response. In this paper the mathematical modelling and simulation of the hydraulic turbine and governing system by using MATLab SISOTOOL has been presented. In addition, stability of turbine has been simulated in MATLab environment and has been shown by varPower system performance is affected by dynamic characteristics of hydraulic governor turbines during and following any disturbance, such as occurrence of a fault, loss of a transmission line or a rapid change of load. Accurate modelling of hydraulic system is essential to characterize and diagnose the system response. In this paper the mathematical modellinious stability plots like, Bode plot, root locus plot, and Nyquist plot.

Keywords: Governor, sisotool, turbine, zozzle, stability plot

Pages: 34 - 37 | DOI: 10.15224/978-981-07-7021-1-39

6. A ROBUST APPROACH FOR CONSTRUCTION OF IRREGULAR LDPC CODES

Authors: ASHISH GOSWAMI , RAKESH SHARMA

Abstract: The future communication systems aim at effective error control coding methods with effective error performance and considerable code rates. LDPC codes are again gaining popularity in future communication systems due to ease in encoding design, effective BER and accept-able code rate. This paper presents a new method for constructing an irregular LDPC codes from low column weight LDPC codes. It is discussed that theproposed method has simple encoding process and less memory requirements. It has been shown that proposed method improves BER performance on AWGN channel by approx. 1 dB per extension level with only slight reduction in code rate.

Keywords: LDPC Codes, Irregular LDPC Codes, Column Weight Code Rate, Parity Check Matrix.

Pages: 42 - 45 | DOI: 10.15224/978-981-07-7021-1-69

7. A LOW-POWER SAMPLE-AND-HOLD AMPLIFIER USING 0.05-µM CMOS TECHNOLOGY

Authors: HIMANSHU PUNDIR , RITURAJ SINGH RATHORE , VINOD KUMAR

Abstract: This paper presents a sample-and-hold circuit based on a cascode-miller compensation technique, utilizing a class-AB operational amplifier as an output stage. Also using the techniques of pre-charging and output capacitor coupling can mitigate the requirements for the op-amp, resulting in low power dissipation. Power consumption is about 300µW from a single 1-V power supply. The performance of this SHA is not degraded even if input frequency approaching up to Nyquist frequency.

Keywords: — Sampling, Sample and Hold (SHA), ADC (Analog to Digital Converter), Power Consumption.

Pages: 38 - 41 | DOI: 10.15224/978-981-07-7021-1-40

8. AN OMNI-PROTECTION SCHEME FOR CLASS-D AMPLIFIERS

Authors: BING-SHIUN HSIEH

Abstract: Class-D amplifier has been a popular device because it features very high power efficiency. However, with increasing power demand, the over-current/-voltage/-temperature protections of amplifiers are necessary to prevent over-heated damage caused by consuming large power consumption over a long time. This paper thus presents the method to dynamically reduce the total power loss of class-D amplifier according to the feedback signal of temperature sensor. The proposed scheme simultaneously reduces the static and dynamic power loss by lowering current delivery progressively and enabling parts of segmented power stages that are in need of conduction. The simulation results show that the total power loss (i.e. excessive heat) and relative temperature difference on chip packages can be reduced to 5.8% of the maximum value that is 12% improvement than that of conventional design. Moreover, the corresponding improvement on power efficiency is over 19% for the cases of small modulation indexes

Keywords: decision support system, web-based decision making , Knowledge management, dairy resource management

Pages: 7 - 11 | DOI: 10.15224/978-981-07-7021-1-33

9. EVANESCENT FIELD MONITORING FOR SIGNAL ENHANCEMENT OF GOLD NANOPARTICLES FILLED SURFACE PLASMON RESONANCE SENSING

Authors: BOONSONG SUTAPUN , CHARDCHAI KORJITTAVANIT

Abstract: The signal enhancement using the evanescent electric field monitoring in the gold nanoparticles (AuNPs) filled surface plasmon resonance (SPR) biosensing is of interest here. The profiles of average evanescent electric fields in a direction normal to the gold/saline layer interface of the 2-dimensional (2D) system are generated at various surface AuNP densities. The shift of the corresponding power density profile increases consistently with the density. The SPR curves associated with dielectric effects from AuNPs are next determined. It shows that the SPR curve shift also possesses the similar characteristic to that of the evanescent field. The evanescent field approach may thus be a potential tool for analyzing SPR signal enhancement.

Keywords: Electric field distribution, Gold nanoparticles, Maxwell-Garnett, SPR enhancement, Surface plasmon resonance

Pages: 21 - 24 | DOI: 10.15224/978-981-07-7021-1-36