Closing workshop of the project was held

On Monday, December 18, 2017, closing Workshop with Presentation of the Research Results of the Project "Ultrasound System for Complex Material Parameters Determination in Nonlinear Working Conditions (ULTRASNON)", conducted in partnership with the University of Zagreb Faculty of Electrical Engineering and Computing (FER) and Institute for Nuclear Research INETEC, d.d., Zagreb , was held.

Presentation of project research results was as part of the project workshop. Presenters were from University in Zagreb (Faculty of Electrical Engineering and ComputingFaculty of Food Technology and Biotechnology) and from industry (Institute for Nuclear Research INETEC, d.d.).

At the end of agenda there was a lunch where all the colleagues were able to discuss topics and questions regarding project results.

In the picture above you can see opening presentation of prof. dr. sc. Antonio Petosic, project leader.

Autor: Petar Franček
Presentation of the Research Results

Closing Workshop with Presentation of the Research Results of the Project "Ultrasound System for Complex Material Parameters Determination in Nonlinear Working Conditions (ULTRASNON)", conducted in partnership with the University of Zagreb Faculty of Electrical Engineering and Computing (FER) and Institute for Nuclear Research INETEC, d.d., Zagreb , will be held on Monday, December 18, 2017.

We invite fellow teachers, postdocs and doctoral students and students to seize this opportunity for socializing. We look forward to your visit!

For more information, please read the article.

Autor: Petar Franček
Presentation of a LoskSam/AcuLab...

In a pleasant and comfortable atmosphere with the large number of potential students and school pupils, the day of the open doors of the Faculty of Electrical Engineering and Computing at the University of Zagreb was held on 25.11.2017. Visitors could get acquainted with the study programs of the FER, laboratories and a varity of scientific research and projects. Representatives of student associations and clubs provided information on student upgrades, exchanges and practices, and participation in sports competitions, excursions, and student life for future students. Teachers, students and staff of the faculty were available throughout the day for all visitors. For visitors the door was open from 10am to 4pm. At the entrance to the faculty there was a marked starting point from where the guided tours of the faculty went. In the tours were seen experiments from physics, experiments with sound, and Tesla's experiments and lightning. Along with the experiments, FER was presented to visitors at hall B4 starting at 12.30 pm and a moderated discussion that brought together the current and graduated FER femail students, FERgirl Tea Party.

Till this year at the days of the open doors the Department of Electroacoustics was present with the lectures and experiments presented to the visitors on the Xth floor of the C building of FER, but this year for the first time the departmant was presented in the main hall of the faculty. The Project Research Laboratory LoskSam / AcuLab was presented as part of the presentation of the institute. Attached to the this link you can download the poster in Croatian. 

Autor: Petar Franček
ULTRASNON at The Institute of...

The Institute of Thermomechanics is a scientific and research institution of the Academy of Sciences of the Czech Republic (Research Area of Mathematics, Physics and Earth Sciences > Section of Applied Physics). The Institute conducts interdisciplinary basic research in fluid dynamics, thermodynamics, dynamics of mechanical systems, solid mechanics, interactions of fluids and solids, environmental aerodynamics, biomechanics, mechatronics, electrophysics, electrical machines, drives and power electronics and material diagnostics.

After the end of the IXth NDT in Progress Workshop members of the project team decided to visit The Institute of Thermomechanic. In a pleasant atmosphere laboratories and test facilities were presented by researchers and other employees to ULTRASNON team members. Visit has ended with demonstration of ultrasound monitoring of a high pressure steam pipe from power plant. 

Autor: Petar Franček
IXth NDT Prague 2017

From October 9 to 11 2017 members of the project team were on the workshops "IXth NDT in Progress" in Prague (Czech Republic). All topics covered by this workshop are closely related to the ULTRASNON project's field of research. Along with the presented results from the industry and experience of the real conditions,  detailed measured results of a project goal, the characterization of the nonlinear field of actuator were presented. During the visit, team members had the opportunity to make acquaintances and make contacts with experts for the development and maintenance of ultrasonic instruments, thus creating the conditions for potential future cooperation.

Autor: Petar Franček
Creation of a NDT transducer

In collaboration with the project partner INETEC we have designed a non-destructive testing actuator. For the purpose of complete characterization, ceramics with wires soldered on has been measured. Second measuring has followed with mounted epoxy backing on ceramics. In the current phase, an insulating cover and housing are in production after which the transducer measurement will be repeated. Characterization results are published in project publications and the following results will be complemented in future papers. 

Autor: Petar Franček
Arrival of a new testing equipment

Few days ago new elements of the modular test assembly have arrived. With the obvious difference in the material much greater difference in the measurements will be anointed with new dimensions. The measurement results will be recorded and published in the future work and papers.

Autor: Petar Franček
More piezoceramic samples arrived

In the last few week various ultrasonic actuators have arrived in our laboratory. There are samples from under 1mm  up to 10mm thickness, with different shapes, sizes and material. Depending on its properties newly arrived ceramic actuator is going to be tested in all compatible predefined measuring configurations and results will be compared with the other measurement results.

Autor: Petar Franček
ULTRASNON Summer Workshop Continued

On 20th July 2017 workshop from week before was continued. Number of attendees has grown by joining more colleagues from INETEC institute what lead for even better argumentation. Measuring with methods used on the last workshop was repeated on newly received actuators. Results have been recorded and stored for further analysis. 


Autor: Petar Franček
ULTRASNON Summer Workshop

On 14th July 2017 colleagues from project partner INETEC visited a laboratory located in Faculty of Electrical Engineering and Computing to be present while performing various laboratory setups and measurements. Workshop has started in the morning and finished late in the afternoon.

In pleasant atmosphere prof. dr. sc. Petošić has acquainted attendees with all details about measurement setup and procedure. Among other measuring procedures on ultrasound transducers 2 were most used:

  • frequency sweep using BODE analyzer with proprietary Matlab automatization scripts
  • observing reflexion on the oscilloscope using pulse and burst excitation

Results and conclusions will be used in the construction and design of a new commercial ultrasound transducer produced in INETEC.

The workshop has ended with a gathering of all participants in the debate and calm discussion in a local restaurant.

Autor: Petar Franček
Review results and new project deadline

In the decision received on 20th June 2017. there are results of a Croatian science foundation reviewing council. The review was successful. All proposed modifications were accepted with some minor remarks. Reviewers were satisfied with project progress so they have determined new project deadline. Deadline is prolonged for four months and now it is till 31. December 2017. 

Autor: Petar Franček
New piezoceramic samples arrived

In order to improve and expand results new ceramic has arrived. By its properties it is closer to the softer types of piezo ceramic and this will be confirmed with our measuring procedures. The new ceramic actuator is going to be tested in all predefined measuring configurations and results will be compared with the other measurement results.

Autor: Petar Franček
Ongoing measurements

After putting together and assembling complete measurement setup, results have started tu pile up. There are few different methods for measuring non-linear characteristics of piezocheramic:

  • method that uses osciloscope and BODE analyzer with impedance adapter 
  • UI method using osciloscope and  BODE analyzer
  • phase skidding using generator and osciloscope
  • burst excitation of piezocheramic
  • resonance frequency with different excitation levels

For all measurements generated signal is amplified with E&I 2100L amplifier and along with temperature there are various parameters collected and saved. All that parameters can and will be used in further research. 


Autor: Petar Franček
Equipment assembled, testing in progress

Simulation equipment has been assembled. It can be used in various scenarios, and in different settings. It can have one or multiple chambers where every chamber can be filled with different medium. Its design fits the best with liquids, but it can be filled even with gas. Also, as shown in the picture, primary setup is with 2 ceramic actuators (one used for transmitting, and one used for receiving ultrasound waves), but it is not the only setup. It can be used with 1 ceramic driven by burst signal. Wholes on surface are custom drilled for inserting and moving sensors in positions calculated in advance.

Autor: Petar Franček
Creation of simulation equipment for...

After calculating and designing shapes and volumes of chambers new testing equipment has been made and delivered. It will be used to simulate realistic environment for determining parameters around the resonance frequency of the ultrasound waves actuated by piezo ceramic elements. For testing purposes ultrasound waves will be spread in various types of a liquid medium. Designs and calculations have been created by project researchers and equipment has been made of plexiglass materials.

Now it is time to assemble and to test leakage. Fingers crossed...

Autor: Petar Franček
New sensor installed

For better measurements and ceramic characterisation new hermetic temperature sensor has been installed. It is designed to be used with less minor modifications of a current setup for measurements within liquid medium. Its compatibility with already used measuring devices assures meaningful comparison of measurements results with this and other sensors.

Autor: Petar Franček
Electrical, acoustical and...

The electromechanical characterization of the ultrasound device in air and in the loading medium has been done by measuring the input electrical admittance, tip displacement, and acoustic pressure at different excitation levels below and above the cavitation threshold. The results of impedance measurements are fitted with a simplified theoretical model of RLC equivalent circuit describing the transducer electrical behaviour in unloaded and loaded conditions and at different driving conditions. Acoustic pressure distribution has been measured in a small sonoreactor in several measurement points, and acoustic intensity and radiated acoustic power have been estimated from RMS acoustic pressure assuming diffuse sound field. The radiated acoustic power estimated from averaged acoustic pressure signal has been compared with the output acoustic power measured using the calorimetric method at different excitation levels, and with the results of electromechanical characterization. The electroacoustic efficiency factor at extreme nonlinear driving conditions has been compared with the results of low-level impedance/transfer function spectroscopy for unloaded and loaded transducer in different sonoreactor configurations.

Autor: Antonio Petošić
Algoritham for tracking resonance...

The parameters of acoustic systems such as piezo-actuators and sensors are usually determined at low excitation levels using the frequency sweeping signals around the resonance frequency of interest. This work investigates the possibility of implementation of an acoustic measurement system on the FPGA platform, in order to increase the speed at which the measurements are performed and the resonance frequencies are determined. The classical frequency sweeping signal measurement is implemented. The resonance frequency at different excitation levels is determined with up- and down-sweeping signals. In real operating conditions, the resonance frequency and the magnitude of admittance and/or displacement is changing. The reason for this change are the nonlinear effects that occur in devices and loading mediums, and also the changes in thermodynamical conditions. The algorithm for tracking the resonance frequency is implemented as well. It is based on the examination of the phase characteristic and of the local maximum of admittance/displacement around the resonance frequency. The algorithm is implemented in real time due to the influence of nonlinear effects and constantly changing thermodynamical conditions in high-power applications of ultrasonic transducers.

Autor: Antonio Petošić
Measurement of pressure distribution...

In cooperation with Associate Professor Anet Režet Jambrak from the Faculty of Food Technology and Biotechnology the measurements of dynamic pressure in small sonoreactor at different applied electrical power to the considered ultrasound system has been done. The measured electrical parameters (voltage, current, power) of the considered ultrasound system with sonotrode and measured acoustical parameters (overall acoustic energy from  1-D pressure signals in echoic reactor) will be connected with efficiency of the process expressed with enthalpy,entropy and number destroyed microorganisms in considered solutions.

Autor: Antonio Petošić
Measuring the properties of the...

Several piezoceramic samples have been characterized by using different thermodynamical and excitation conditions in thermal isolated oven at INETEC L.t.d. It has been observed strong coupling between thermodynamical effects induced by different temperatures (from 25 degrees up to 125 Celsius degrees)  and nonlinear effects induced by large excitation fields of piezoceramic samples.  

Autor: Antonio Petošić
Measuring attenuation and speed...

In cooperation with INETEC team the measurement of longitudinal acoustic waves attenuation and sound wave velocity in soils has been done. The purpose is to develop an high power ultrasound system for detection of soil pollution. The all project team members from host institution and INETEC L.t.d. have been included in the task.

Autor: Antonio Petošić
Working visit to the EPFL ceramic lab

The principal investigator Assistant Professor antonio Petošić and Ph.D Marko Horvat visited EPFL ceramic lab. The project collaborator, Research Professor Damjanović showed us the measurement equipment and we have done some basic displacement and  velocity measurements of the APC 841 piezoceramic sample around thickness mode of working with MTI 2100 Photonic sensor. 

Autor: Antonio Petošić

The team members presented work about using novel algorithm for tracking resonant frequencies of piezoceramic samples and ultrasound transducers at different driving and loading conditions at ICU 2015 Conference in Metz. The conference lasted from 10. May till 14. May. The paper was written by Antonio Petošić, Marko Horvat, Petar Mateljak and Marko Budimir. It was observed that losses at resonance of piezoceramic samples are significantly increased when excitation level is increased due to coupled nonlinear effects and temperature increase in the device under test.

Autor: Antonio Petošić
Characterization of piezoceramic...

A MATLAB application has been developed for characterization of piezoceramic elements and transducers operating in the thickness-extensional mode. The input data is the impedance or admittance measured with Omicron BODE 100 analyzer. The ouptuts include real parameters of the equivalent RLC circuit, determined in the usual manner, using the so-called forward approach. Improvements to this method have been made and a reverse approach method has been defined for determining the values of the elements in the RLC circuit. The results show that the admittance of a piezoceramic element modeled with parameters obtained from the reverse approach is in better agreement with the actual measured admittance, thus justifying the proposed approach. Sherrit characterization with complex parameters has been implemented as well.         

Autor: Marko Horvat
Measurements of attenuation of...


In cooperation with INETEC L.t.d. and the host institution, the measurement setup for measuring attenuation of ultrasound waves in soil samples has been implemented. 

Autor: Antonio Petošić
The system for automatic acquisition...

The measurement system capable of automatic acquisition of RMS values of current through devices under test (DUT), i.e. piezoceramic elements and assembled ultrasonic transducers, and voltage across them. The system is also capable of measuring the sound pressure produced by the DUTs when excited with electrical signal, as well as measuring and monitoring the temperature changes exhibited by the DUTs as a result of high-power excitation during tests and measurements. The system consists of the OMICRON Lab BODE 100 vector/network analyzer, Agilent Technologies MSO-X-3024a mixed signal oscilloscope, Keysight 33500B waveform generator, Tektronix TCP312 current probe with Tektronix TCPA300 amplifier, Bruel&Kjaer Nexus conditioning amplifier, Keysight N2790A and Testec TT-SI 9001 differential probes, and Electronics & Innovation 2100L RF power amplifier with JT-6 matching transformer. 

Autor: Antonio Petošić
Employment on the project


On December 1st, 2014 postdoc researcher Marko Horvat was employed on this project.

Autor: Sanja Grubeša
Research laboratory equipment and...


The procurement of the equipment required for the excitation part of the measurement system to be used for material characterization has been completed.


The project has been presented at the Faculty of Electrical Engineering and Computing Day (21.11.2014) with poster.

Autor: Sanja Grubeša


The project began on September 1st,  2014.

Autor: Sanja Grubeša