[IEEE 2013 IV International Conference on Power Engineering, Energy and Electrical Drives (POWERENG)...

Design and Implementation a Microcontroller based High Power Ultrasonic Dispersion System with self

Frequency adjusting property

Javad Abbaszadeh

Control and Instrumentation

Engineering Department, FKE,

Universiti Teknologi

Malaysia, Johor Bahru, Malaysia

JAB@fkegraduat

e.utm.my

Esmaeil Najafiaghdam

Electronic Department, Faculty of Electrical

Engineering, Sahand

university of Technology, Tabriz, Iran

[email protected]

Herlina Abdul Rahim Control and

Instrumentation Engineering

Department, FKE, Universiti Teknologi


[email protected]

.my

Ruzairi Abdul Rahim





[email protected]

.my

Sahar Sarafi

Electronic Department, FKE,



[email protected]

Abubakar Suleiman





Abstract- In This paper a novel ultrasonic dispersion system

for the cleaning application or dispersing of particles which are mixed in liquid, has been proposed. The frequency band of designed system is 28 kHz so that the frequency of ultrasonic wave sweeps from 20 kHz to 30 kHz with 100 Hz steps. Transferring a maximum and optimum energy of ultrasonic wave to the liquid conveyor with high efficiency during total usage time is remarkable superiority of designed and manufactured system compares with other similar available systems in markets. High power ultrasonic transducers with the nominal maximum power 110 watt are applied as the ultrasonic wave generator. To increase the efficiency of system and transmitting the maximum energy to the liquid tank, the frequency of system should set on the resonance frequency of transducer. Control section is implemented in system for real-time monitoring and adjusting the frequency of system. Hall Effect current sensor is used as the current sampling component and controlling program is implemented on AVR microcontrollers. The manufactured ultrasonic dispersion system is consisted of 4 high power ultrasonic transducer result in 450 watt ultrasonic energy, effectively.

Keywords-ultrasonic dispersion; ultrasonic transducer; high power; frequency controlling

I. INTRODUCTION

Ultrasonic cavitation is a physical phenomena leads to dispersion and deagglomeration of mix particles suspended in liquid. Propagation of sound waves into the liquid media results in alternating high-pressure (compression) and low pressure (rarefaction) cycles, with rates depending on the frequency. During the mentioned cycles, small vacuum bubbles are created and collapsed violently. Implosion of vacuum bubbles cause to very high temperatures and

pressures locally. The implosion of the cavitation bubble also results in liquid jets of up to 280m/s velocity [1].

Application of mentioned phenomena is applied in ultrasonic dispersion system. The dispersing power of a liquid tank depends on how strong the bubbles collapse. Existence of any gases inside the solution reduces the pressure of that region, which finally prevents the strong collapsing of the bubbles. Since the ultrasonic wave cause to creation of cavitation, ultrasonic wave should produce by an ultrasonic system [3]. The whole structure of proposed ultrasonic dispersion system in block diagram form is shown in Figure 1. All of the blocks will be explained in the next subsections accurately. Pulsing is most commonly done by means of a pulsing circuit provided integrally in the body of high quality ultrasonic generators. Therefore, microprocessor based generator implementations are widely preferred for the designers [4]. In this study, such an ultrasonic generator system, which has a novel software algorithm and a power-driver circuit, has been designed, implemented, and tested [2].

Figure 1. Block diagram of ultrasonic dispersion system. As can be seen on figure 1, ultrasonic transducer is one of

the important parts of the system to produce the ultrasonic wave by vibration. The applied transducer in system is a kind of composite piezoelectric transducers in the sandwich form

978-1-4673-6392-1/13/$31.00 ©2013 IEEE670

4th International Conference on Power Engineering, Energy and Electrical Drives Istanbul, Turkey, 13-17 May 2013

POWERENG 2013

with backing and horn to amplify the intewave.

The method of transducer mounting on tand impedance matching of transducer wpreliminary conditions for transferring theThe major benefit of designed system cosystems is delivering of efficient high energy during its working time by automfrequency of system on resonance freqmonitoring of system is done with frequexciting signal, comparing with maximumback the new result to microcontroller.

Liquid tank must be made of stainless sas thin as possible. Ultrasonic transducersbottom of the tank by using special glutransducers to be placed and the distandepend on the size of the tank. There “immersible transducers” on the market.inside the dispersing liquid by using a wabox, in which transducers are mounted.

In this paper, brief introduction to ultrand their frequency characteristic will be then followed by a presentation of powesystem and its fundamental parts. Control is presented at the next section anexperimental results of manufactured sdemonstrated. Conclusion is presented in t

II. ULTRASONIC TRANSDUC

There are two types of transducersultrasonic applications, magnetostrictive Due to our considered objectives, piezoeare selected as the transducers of Piezoelectric transducers utilize the piezoea material to convert electrical enermechanical energy [10,11]. The metransducer is consist of multiple piezoarranged in sandwich form among the batransducers. Typical construction of stransducer is shown in figure 2 [15]. Wheto amplify the intensity of the ultrasonic the applied wave to liquid tank, piezoeleultrasonic wave with mechanical vibrationproper exciting signal and backing prevenof ultrasonic wave in back direction [12,15

Figure 2. Typical structure of ultrasonic

A. Electrical model of ultrasonic transduThe Frequency characteristic of ultraso

the resonance frequency region can be d

ensity of ultrasonic

the surface of tank, with tank, are the

e ultrasonic energy. ompares with other

power ultrasonic matic adjusting the quency. Real-time uency sweeping of m current and feed

steel and it must be s are located on the ue. The number of nce between them are also so called They are located ater resistant metal

rasonic transducers presented. This is

er amplifier part of part of the system

nd ultimately the system have been the last section.

CERS

used for power and piezoelectric.

electric transducers proposed system. electric property of rgy directly into entioned selected electric plates are acking and horn of selected ultrasonic ere horn part cause wave and uniform

ectrics produce the n in the influence of nts the propagation 5].

transducer.

ucers onic transducer on

described using the

Butterworth-Van Dyke (BVD) (Rs, Ls, Cs) and the electrical C0) of the transducer are shown

The losses described by R1, c Where R0 describes the diel

material and Rxm the acousAssuming Rxm is the largest pacan be considered as the trameasure [7]. The derived impedance is given by:

From Eq.2 the resonance fre

achieved by [7]:

and the parallel resonance [7]

The parameters of our used

been presented in table1.

Figure 3. Butterworth-van

TABLPARAMETERS OF ULTRA

Type Length (mm)

Frequenc(kHz)

CCH-6850D-

28LB PZT-4

66 28

B. Impedance matching Acoustic impedance of variou

of equation as follow:

Where Z is the acoustic im

medium and c is the sound speesystem, various interactions eenergy from transducer to insid

model. The mechanical parts parts (the clamping capacitor

n on figure 3 [6]. an be split:

(1)

ectric losses in piezoceramic stic emission into medium. art, the power supplied to R1 ansducer acoustic efficiency ultrasonic transducer input

(2)

equency of transducer can be

(3)

]:

(4)

d ultrasonic transducer have

n dyke transducer model.

LE I ASONIC TRANSDUCER

cy Impedance

Capacitance (pF) 10%

10-20 7800

us media calculates by the use

(5)

mpedance, is the density of ed. In the mentioned designed exist to send the ultrasonic de the liquid tank. One of the

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interactions is among the transducer coouter surface of liquid tank. Trapping an asurfaces causes to reflection and attenuawave. It is assumed the acoustic impedantank equal to 430 and 44.6×106, respectivereflection wave calculated as fallow:

The big value difference of impedancesteel and air is the main reason of refleliquid type of coupling material (wet coallow easy application and conformity tothe transducer and the surface. It also shouconductor of sound energy to allow maximstructure [13]. Other characteristics of cougenerally dependent on particular applicmore viscous coupling material would be fill in the roughness, for the rough-surfaThe proposed acoustic coupling as used silicone sealant, which is a viscous matstate to become solid when it dries off. Thmaterial, ensure the transmition of maultrasonic wave to inside the liquid tank.

III. CIRCUIT OF TRANSMITT

Since the selected ultrasonic transducpower transducers and for exciting theamplitude voltage and current. This is supamplifier circuit. Various types of amplifcan do the similar work but with differencategories of power amplifiers are as follow

1. Linear power amplifiers by thjunction transistors such as ClassAB and etc)

2. Power switching amplifiers by adfor impedance matching andvoltages such as class E, Class D

For example the class-B amplifier usinghave a theoretical performance estimatedmost cases, these amplifiers available odesigned for audio systems and are not uultrasonic transducers operating at high the first category needs a lot of elementhigh resistivity which leads to increasing onot affordable to choose the first choice aspart of ultrasonic system [8,9].

However, power Mosfets makes it poclass-D power amplifiers for high freqoverall efficiencies around 95% [9]. The consists of various parts with different tasas the block diagram in figure 4. The inpuwidth modulation signal (PWM) thamicrocontroller, the generated PWM signisolation part to distinct the high power p

ontact surface and ir gap between two ation of ultrasonic nce of air and steel ely. The amount of

(6)

e between stainless ction. Normally, a

oupling) is used to o the void between uld be a very good

mum transfer to the upling materials are ations such as the used to effectively

aced material [14]. in configuration is terial that changes

his type of coupling aximum energy of

TER

cers are the high em we need high pplied by the power fiers exist that they nt efficiency. Two w [5]:

he use of bipolar s A, Class B, Class

dding transformers d amplifying the and etc.

g bipolar transistors d at about 78%. In on the market are usually suitable for frequencies. Since

ts and due to their of temperature, it is s a power amplifier

ossible to produce quencies that offer

designed amplifier sks that it is shown ut signal is a pulse-at generates with nal proceed to the part of circuit from

low power part and reduce theon the pulse generator then signbe amplified to drive the power PWM signal is reached to the the power switches with its relat

Figure 4.Block diagram The designed circuit schemat

figure 5. The generated PWMcannot support the driving voadequate current so driver stadrive the power mosfets. The the gate of mosfets the PWMsource of mosfets. The minimrunning the mosfets is 15 volt mA that they are prepared with

Figure 5.Circuit schem The output stage of the transm

full bridge inverter. Class-D cooutput stage of the transmitter the class-D amplifier are switchfull bridge form and LC filteoutput stage is demonstrated in

The topology of a LC resonFigure 6. For the design of thewith [16]:

The value f is selected, tha

the Lf -Cp oscillating circuit is 2resonance below the operating pIn piezoelectric systems with

e noise affection of switching nals is sent to the driver part to

mosfets and finally amplified output stage of circuit to run ted frequency.

m of power amplifier.

tic of driver stage is shown in M signal with microcontroller oltage of power mosfet with age amplifies the voltage to amplified signals proceed to

M signal falls between gate-mum amplitude of voltage for

and minimum current is 150 driver stage.

matic of driver stage

mitter circuit is in the type of onstruction is selected as the of system. The basic parts of hing mosfets in half bridge or er. The circuit schematic of figure 6. nant converter is depicted in e output filter it is calculated

(7)

at the resonance frequency of 20 to 25% of the mechanical point of the transmitter circuit.

high damping the distance

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between the resonance frequencies is much[16].

Figure 6.Circuit schematic of outpu The transfer function of LC filter consi

based on the admittance of two sides canuse of GLC(j ) = Vi(j ) / Vp(j ). Themechanical oscillation circuit on the transfnoticeable at stimulation with mechfrequency ( = 1). At this point of operatfalls below the amplification of 1. In addincreasing rapidly when the mechaniapproached [16].

More suitable conditions are gained byCf for compensation in parallel to reducethe resulting loading system. Unluckily tyields of course higher load currents caustress for the power semiconductors asvoluminous inductor Lf.

The switching circuit consists of 4 powform of full bridge inverter. For describoperation of inverter, some assumptions shassume the voltage name of the joining poT2 (figure 6) is Vm and the voltage nambetween T3 and T4 is Vn (figure 6) anvoltage of inverter. The working methotransistors as follow [17]:

When T1 and T4 turn on:

Vm = P , Vn = 0 then Vm-Vn=P When T2 and T3 turn on:

Vm = 0 , Vn = P then Vm-Vn=-P The A and B signals which are PWM

applied to driver of mosfets. In fact mosturned on during one-half period, and moturned on during the other half period. ThT4 are short circuited to ground at the end period. This choice of driving was adapfreewheeling sequence of the current of loa

The full bridge switch commutation is bootstrap method. To switch a mosfet, voltage VGS must be positive. This is thtransistors T1 and T3. However, for the toknown bootstrap method is used. With thisof the full bridge, the inverter design madeliver a maximum power of about 2 kW and 1.5 kW into a reactive load. To

h smaller (e. g. 10)

ut stage

sted of Lf and Cf is n be achieved with e influence of the fer characteristic is hanical resonance tion the magnitude dition the phase is ical resonance is

y using a capacitor e the impedance of this increased load

using larger current s well as a more

wer mosfets in the ing the manner of hould be taken. we

oint between T1 and me of joining point

d P is the supply od of 4 mentioned

signals which are sfets T1 and T4 are sfets T3 and T2 are hus mosfets T2 and of their conduction pted to generate a ad [17]. done by using the the gate-to-source

he case for bottom op mosfets the well s type of command akes it possible to into resistive load, reduce the high-

frequency noise, capacitors of aas closely as possible to the mProperly designed RC-type snterminals of each mosfet coovershoots during the transition

IV. REAL-TIME

Control part of system as theprocesses and supervises thaccurately. Generally, it provariable frequency, sampling twith the maximum current tresonance frequency of systemof ultrasonic transducer variecapacitance, the level of liquid stiffness of liquid tank have piezoelectric resonance frequenautomatic finding the resonanceto working the system in maxim

The program of software alglanguage is approximately toosoftware algorithm to be run circuit has the following feature

1. Ability to set the operatinrange of 20 kHz-30 kHz.

2. Dispersing-power control b3. Timing control for adjustin4. Automatic power shut-

temperature of power MOSFETlimit.

5. Display controls to indmodes, power adjustment, operation time.

6. Recovering the resonantransducers due to possible dfrequencies resulted from chaanalogue feedback has been paddition to the power unit.

In the main loop of programare set and the proper valueparameters, then interrupt operprevious case has been done oexecute. Ultimately the mode owants to change the operation mby the use of control interface bsystem.

By the pushing of start buttogenerate the PWM pulses. Dchooses with the specified pocurrent of piezoelectric is meacurrent sensor. Output of currcurrent and it is necessary that ito be applicable to the microfrequency of piezoelectric, phawith the phase of flowed curresystem reaches the maximummeasured by the sensor applies

a few microfarads were placed mosfets, as shown in figure 6. nubber circuits placed on the onsiderably reduced voltage ns [17].

CONTROLLING

e brain of system monitors all he performance of system duces exciting pulses with the current and comparing it to fix the frequency in the

m. Since resonance frequency es with the variation of its

inside the tank, temperature, an influence in variation of

ncy. Control part of system by e frequency in real-time cause

mum power. gorithm which is written in C o long. Here, the developed on the AVR microcontroller

es: ng frequency manually in the

by PWM pulses. ng by the user. -down property when the Ts overflows the temperature

icate temperature, operating frequency adjustment, and

nt frequency of ultrasonic deviations on their resonant anges on tank loadings. An proposed for this purpose in

m, the primary circumstances es allocated to the primary ration for the retrieval of the

or the new commands of user f operation is selected. If user mode of system, he can do it board which is located on the

on, microcontroller begins to Duty cycle of PWM pulses ower of system. The flowed asured by the in line located rent sensor is in the form of it converts to the voltage form ocontroller. In the resonance ase of applied voltage equals ent and in this case current of m value. Voltage which is s to the analogue comparator

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pin of microcontroller and it compares with the source voltage (the voltage in resonance frequency of piezoelectric).

The real-time method of controlling the power is the produced PWM pulses starts to frequency sweep to extract the resonance frequency of system by the finding of maximum flow current from piezoelectric. Measured current converts to voltage and by the analog to digital convertor of AVR microcontroller converts to digital and saved in memory of microcontroller temporarily. Then the frequency of system is set on the determined frequency until the amount of flowing current changes. While the amount of current varies the frequency sweep repeat to find the new resonance frequency.

Figure 9. Flowchart of main program

Automatic frequency adjusting is done by the execution of

following steps. As we know from the data sheet of piezoelectric, the resonance frequency of piezoelectric without load is 28 kHz so at first, frequency sweep is done from 20 kHz to 30 kHz with the 100 Hz steps. The mentioned sweeping is done until the detection of maximum current then frequency locks on the detected frequency. While the maximum current does not exist in the mentioned frequency band then frequency band of sweeping has been extended from 20 kHz to 35 kHz.

When the frequency of system locks on resonance frequency, time counter starts to work (it shows the working time of system which is determined by user). In addition, temperature control of system is such that detected voltage from temperature sensor which is connected to the container of liquid sends to the ADC pin of microcontroller in each 10

seconds and it compares with the critical temperature of system.

Time controlling method is such that the entire working time of system adjusts with the keypad by the user. While the system suddenly is switched off for any reason, the rest of time is saved in microcontroller and with the restarting, system asks the user if it continues the before settings or rest the system to initial settings. The flowchart of main loop of program is demonstrated in figure 9.

.

V. EXPERIMENTAL RESULTS

High power circuit of system which its schematic demonstrated in previous sections, are shown in figures 10 and 11. Figure 10 shows the DC supply part of circuit that it can produce 150 V. This part is consist of regulators for supporting other parts (except output stage) DC voltage and diode bridge and electrolyte capacitance for rectify of voltage. Maximum current that it can support is 8 ampere. In the next figure, control part of system and output stage of power amplifier part is illustrated. The first component of control part is AVR microcontroller. Two important tasks of this microcontroller are generating the PWM pulses with 50% duty cycle and automatic frequency adjusting of system. Other shown component in figure 11 is Hall-effect current sensor. The model of the mentioned sensor is CSNE 151 -100 and the method of connection between ports of current path depends on the maximum flowing current. The output of current sensor is current in mA range then it converts to voltage and feedback to the ADC port of microcontroller.

Power mosfets of output stage which construct the full bridge structure of output stage is shown in figure 11. These mosfets are the type of IRFP-460n and they tolerate 500 volt peak to peak voltage and 20 A current. Due to the small drain-source resistance (0.24 ) the switching rate of used mosfets are so high. The rate of switching cause to the slew rate of pulses in output is as our desire. Since the current with amount of 6-8 A flows through the output stage, the temperature of the used mosfets increase. Suitable heat sinks with calculated dimensions to cool the transistors are implemented.

Ferrite core which is demonstrated in figure 11, is the type of EE65 to support the high amplitude of current. Designing of ferrite transformer is a complicated process such as determining the air gap between the cores and calculating the first and secondary wiring ratio. Value of inductance of primary winding is 4.2 mH and secondary inductance of transformer is 68.4 mH.

Square PWM pulses with duty cycle of 50% are shown in figure 12. These pulses after generation with microcontroller and after passing through the isolator with mosfet driver part are amplified. The probe of oscilloscope is on the 0.1 attenuation mode and the shown pulses value is about 20 volt peak to peak. Figure 13 shows the applied voltage on piezoelectric. The shape of signal seems to sine wave due to the affection of RLC tank in output stage. The value of voltage is about 450 volt peak to peak (probe of oscilloscope is on 0.1 attenuation mode).

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FIGURE 10. DC SUPPLY OF SYSTEM

FIGURE 11. PCB OF DESIGNED CIRCUIT

FIGURE 12. DRIVER SIGNAL OF OUTPUT STAGE

FIGURE 13. OUTPUT SIGNAL OF CIRCUIT TO EXCITE THE TRANSDUCERS

FIGURE 14. ULTRASONIC DISPERSION SYSTEM

The structure of designed system is shown in figure 14. There is key pad and graphic LCD and some bottoms as start, stop and menu for adjusting the working time of system and power of system. These bottoms are the facilities of system implemented to adjust with users. A tap is implemented in liquid tank to vacate the dispersed particles suspended in liquid.

VI. CONCLUSION

In this paper a novel ultrasonic dispersion system with Automatic frequency adjustment is proposed. Its frequency band ranges from 20 kHz to 35 kHz and a maximum power of 440 W is delivered. The system consists of 4 ultrasonic transducers positioned on the bottom of stainless steel tank.

The designed system has a wide application in industry especially in chemical industry. Nano powder production is an interesting field that a lot of researchers investigate on it in early decades. The designed system compares with other system for producing nano powder has a significant priority. It has been used in the Catalyst laboratory and its performance compares well with the other ultrasonic dispersion system. The system’s application decreases the total time of nano powder produced. The total time of nano powder producing by the use of this system is decreased considerably. The uniformity and quality of powder are also in good condition.

.

REFERENCES [1] L.Thompson, L. Doraiswamy. Sonochemistry: science and engineering,

Industrial and Engineering Chemistry Research 38 (4), 1215-1249, 1999.

[2] M.Yakut, A.Tangel, C.Tangel, “A microcontroller based generator design for ultrasonic cleaning machines” journal of electrical & electronics engineering , volume 9, pp.853-860, 2009.

[3] C. Buasri, A. Jangwanitlert, “Comparison of switching strategies for an ultrasonic cleaner”, 5th International Conference on Electrical Engineering / Electronics, Computer, Telecommunications and Information Technology, ECTI-CON pp. 1005-1008, 2008.

[4] A.Jangwanitlert, P.Paisuwana and T.Vijaktakul, “Ultrasonic cleaner” proc, in EECON 22,Kasetsart University, Vol 22,2542, 1999.

[5] Ramok’P,ms A., Emeteriao J. L. S, “Improvement in transient piezoelectric responses of NDE transceivers using selective damping and tuning networks”, IEEE transactions on ultrasonics ferroelectrics and frequency control. Vol 47. No 4. P. 826-835, 2000.

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[6] H. Kifune, Y. Hatanaka and M. Nakaoka, “Cost effective phase shifted pulse modulation soft switching high frequency inverter for induction heating applications”, Proc. IEE Electrical Power Appl. Vol. 151, pp. 19-25, 2004.

[7] L. Svilainis, G.Motiejunas, “Power amplifier fr ultrasonic transducer excitatin” ULTRAGARSAS, Nr.1 (58), pp. 30-36, 2006.

[8] T.Suzuki, H.Ikeda, Y.Mizutani, T.Nakabori, Y.Ichioka, H.Yoshida, K.Honda, T.Miyamoto, and S.Sano, “Full-Bridged MOS-FET DC-to-RF Inverter for High Frequency Ultrasonic Transducer at 3 MHz”, IEEE ISIE’95, pp.232-236, 1995.

[9] J. Ishikawa, Y. Mizutani, T. Suzuki, H. Ikeda, H. Yoshida, “High-frequency drivepower and frequency control for ultrasonic transducer operating at 3 MHz”, Industry Applications Conference, 1997. 32. IAS Annual Meeting, IAS '97,Vol. 2, pp. 900-905, 1997.

[10] Domarkas V., Ka.ys R.-J.” Piezoelectric transducers for measuring devices”. Vilnius: Mintis P. 255, 1975.

[11] Le Locle, “Piezoelectric Converters Modeling and Characterization” published by M.P. Interconsulting, E-book, 266 pages, August, 2004.

[12] M. H. Fazalul Rahiman, R.Abdul Rahim, J. Pusppanathan, “Two-Phase Flow Regime Identification by UltrasonicComputerized Tomography” Sensors & Transducers Journal, Vol. 116, Issue 5, pp. 76-82, May 2010.

[13] A. Kannath and R. J. Dewhurst, “Real-time measurement of acoustic field displacements using ultrasonic interferometry,” Meas. Sci. Technol., vol. 15, pp. 59–66, 2004.

[14] M. L. Sanderson and H. Yeung, “Guidelines for the use of ultrasonic non-invasive metering technique,” Flow Meas. Instrum., vol. 13, pp. 125–142, 2002.

[15] D.Ensminger and F. B. Stulen, “ULTRASONICS, Data, Equations, And Their Practical Uses” Taylor & Francis Group, LLC, 2009. [16] C. Kauczor, T. Schulte, N. Fröhleke, “RESONANT POWER

CONVERTER FOR ULTRASONIC PIEZOELECTRIC CONVERTER” Institute for Power Electronics and Electrical Drives, University of Paderborn, Germany, 2009.

[17] K. Agbossou, J.L. Dion, S. carignan and A. Cheriti, “Class D Amplifier for a Power Piezoelectric Load” IEEE Transactions on Ultrasonic, piezoelectrics and Frequency control, VOL, 47, NO. 4, pp. 1036-1041, July 2000.

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