Papers by Vladimir Ivchenko
VLSI architecture for repetitive waveform measurement with zero overhead averaging
IEEE International Workshop on Intelligent Signal Processing, 2005., 2005
The architecture and performance of a digital waveform acquisition instrument with built in avera... more The architecture and performance of a digital waveform acquisition instrument with built in averaging is discussed. The substantial time required for averaging in software was eliminated in the developed architecture by using hardware averaging at the speed of waveform occurrence, due to a fully pipelined operation of constituent units. This architecture was implemented using an FPGA development board, and was
Compensation for temperature variation in ultrasonic chemical process monitoring
IEEE Ultrasonics Symposium, 2005., 2005
ABSTRACT Not Available
Development of Electronic Components for an Integrated Ultrasonic Front End ASIC
2007 IEEE Instrumentation & Measurement Technology Conference IMTC 2007, 2007
ABSTRACT The development of an ASIC for ultrasonic front end is described. The ASIC contains a hi... more ABSTRACT The development of an ASIC for ultrasonic front end is described. The ASIC contains a high speed binary driver and broadband amplifier optimised for a conventional piezoelectric transducer. Experimental results that agree well with simulations are presented and discussed.
Accurate Interleaved Sampling of Repetitive Ultrasonic Waveforms: Two Clock Timing Architecture and its FPGA Implementation
2006 IEEE Instrumentation and Measurement Technology Conference Proceedings, 2006
Random interleaved sampling has become a widespread operating mode for digital storage oscillosco... more Random interleaved sampling has become a widespread operating mode for digital storage oscilloscopes. Different repetitions of (notionally) the same waveform are recorded at random time shifts, and are interleaved in memory. This procedure requires substantial time, especially if further averaging is required. In this paper, an approach that ensures accurate time shifts is presented for ultrasonic measurements. Operating two independent oscillators with related frequencies forms the accurate shifts. One of these is used to excite an ultrasonic transducer, and the other to clock the analogue to digital converter (ADC). This architecture was implemented using a commercial "off-the-shelf" field programmable gate array (FPGA). An experimental waveform is presented that was sampled at the equivalent sampling frequency of 2160 MHz using an ADC with a clock frequency of 80 MHz. Power dissipation related to different architectures is discussed
Ultrasonic Measurements of Temperature in Aqueous Solutions: Why and How
Physics Research International, 2011
ABSTRACT The paper describes two different approaches to ultrasonic measurements of temperature i... more ABSTRACT The paper describes two different approaches to ultrasonic measurements of temperature in aqueous solutions. The first approach uses two narrowband ultrasonic transducers and support electronics that form an oscillating sensor which output frequency is related to the measured temperature. This low-cost sensor demonstrated sensitivity of about 40 Hz/K at the distance of 190 mm and the operating frequency of about 25 kHz. The second approach utilised pulse-echo mode at the centre frequency of 20 MHz. The reflector featured a cavity that was filled with deionised water. The ultrasound propagation delay in the cavity was related to the temperature in the solution. The experiments were conducted for deionised water, and solutions of sodium persulfate, sodium chloride, and acetic acid with concentrations up to 0.5 M. In the experiments (conducted within the temperature range from 15 to 30°C), we observed increases in the ultrasound velocity for increased temperatures and concentrations as was expected. Measurement results were compared with literature data for pure and seawater. It was concluded that ultrasonic measurements of temperature were conducted with the resolution well below 0.1 K for both methods. Advantages of ultrasonic temperature measurements over conventional thermometers were discussed.
Super-resolution in situ ultrasonic monitoring of chemical reactions
IEEE Ultrasonics Symposium, 2004, 2004
This paper describes experiments to compare the sensitivity and robustness of ultrasound measurem... more This paper describes experiments to compare the sensitivity and robustness of ultrasound measurements with pH measurements when monitoring chemical reactions under laboratory conditions, the aim being to determine the relative suitability of the two techniques for process monitoring and control. It is shown that ultrasonic time-of-flight measurements, based on the centre of the area of an ultrasonic pulse, provides for
Resolving Complex Chemical Processes: Comparison of Monitoring by Ultrasound with Other Measurement Methods
2006 IEEE Instrumentation and Measurement Technology Conference Proceedings, 2006
... 7 with replaceable tip 6), pH meter (PHM-240, Radiometer, with pH electrode 5 and temperature... more ... 7 with replaceable tip 6), pH meter (PHM-240, Radiometer, with pH electrode 5 and temperature probe 4), magnetic stirrer 1 immersed into a solution under test 2. ... In the considered case the group velocity parameter was found the most noise resilient and sensitive to ...
A field programmable gate array-based ultrasonic spectrometer
Measurement Science and Technology, 2008
... voltage ultrasonic data acquisition system intended for process monitoring of liquid chemical... more ... voltage ultrasonic data acquisition system intended for process monitoring of liquid chemicals in an ... Recent advances in reconfigurable hardware technology such as field programmable gate arrays ... The system is physically compact, potentially of low cost, and could provide the ...
Measurement Science and Technology, 2011
ABSTRACT
Journal of Physics: Conference Series, 2013
This paper describes a system for ultrasonic wave attenuation measurements which is based on pseu... more This paper describes a system for ultrasonic wave attenuation measurements which is based on pseudo-random binary codes as transmission signals combined with on-the-fly correlation for received signal detection. The apparatus can receive signals in the nanovolt range against a noise background in the order of hundreds of microvolts and an analogue to digital convertor (ADC) bit-step also in the order of hundreds of microvolts. Very high signal to noise ratios (SNRs) are achieved without recourse to coherent averaging with its associated requirement for high sampling times. The system works by a process of dithering -in which very low amplitude received signals enter the dynamic range of the ADC by 'riding' on electronic noise at the system input. The amplitude of this 'useful noise' has to be chosen with care for an optimised design. The process of optimisation is explained on the basis of classical information theory and is achieved through a simple noise model. The performance of the system is examined for different transmitted code lengths and gain settings in the receiver chain. Experimental results are shown to verify the expected operation when the system is applied to a very highly attenuating material -an aerated slurry.
Ultrasonic monitoring of foamed polymeric tissue scaffold fabrication
Journal of Materials Science: Materials in Medicine, 2008
Polymeric tissue scaffolds are central to many regenerative medicine therapies offering a new app... more Polymeric tissue scaffolds are central to many regenerative medicine therapies offering a new approach to medicine. As the number of these regenerative therapies increases there is a pressing need for an improved understanding of the methods of scaffold fabrication. Of the many approaches to processing scaffolds, supercritical fluid fabrication methods have a distinct advantage over other techniques as they do not require the use of organic solvents, elevated processing temperatures or leaching processes. The work presented here is centred on the development of a new approach to monitoring supercritical scaffold fabrication based on determination of the scaffold acoustic impedance to inform protocols for scaffold fabrication. The approach taken uses an ultrasonic pulse-echo reflectometer enabling non-invasive monitoring of the supercritical environment on-line. The feasibility of this approach was investigated for two scaffolds of different molecular weight. Acoustic results demonstrate that differences in the physical properties of the two scaffolds could be resolved, particularly during the foaming process which correlated with findings from time-lapsed imaging and micro X-ray computed tomography (micro X-ray CT) images. Thus, this work demonstrates the feasibility of ultrasonic pulse-echo reflectometry to non-invasively study supercritical scaffold fabrication on-line providing a greater understanding of the scaffold fabrication process.
High-Accuracy Data Acquisition Architectures for Ultrasonic Imaging
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000
This paper proposes a novel architecture for a data acquisition system intended to support the ne... more This paper proposes a novel architecture for a data acquisition system intended to support the next generation of ultrasonic imaging instruments operating at or above 100 MHz. Existing systems have relatively poor signal-to-noise ratios and are limited in terms of their maximum data sampling rate, both of which are improved by a combination of embedded averaging and embedded interleaved sampling. "On-the-fly" pipelined operation minimizes control overheads for signal averaging. A two-clock sampling timing system provides for effective sampling rates that are a factor of 20 or more above the basic sampling rate of the analog-to-digital converter (ADC). The system uses commercial field-programmable gate array devices operated at clock frequencies commensurable with the ADC clock. Implementation is via the Xilinx Xtreme digital signal processing development kit, available at low cost. Sample rates of up to 2160 MHz have been achieved in combination with up to 16384 coherent averages using the above-mentioned off-the-shelf hardware.
IEEE Transactions on Instrumentation and Measurement, 2000
A cross-disciplinary experimental study related to both ultrasonic instrumentation and analytical... more A cross-disciplinary experimental study related to both ultrasonic instrumentation and analytical chemistry is reported. The hydrolysis process was conducted by time-resolved titration in a fully automated manner. Acquired ultrasonic records were processed in order to estimate the propagation delay of the ultrasonic pulse in the evolving medium. The limited hardware resolution of two different ultrasonic instruments employed was improved by calculating the center of gravity of the recorded pulses. Application of signal averaging to the acquisition of raw records in the custom-built instrument eliminated spurious records almost completely. The estimated ultrasonic delays were corrected for temperature changes that were measured independently. This procedure transformed the ultrasonic titration curves into two almost straight lines that intersected at the equivalence point. The results obtained showed that it was possible to detect changes as small as 200 ppm by using the ultrasonic instrument in situ at significantly lower setting times compared to a conventional pH-meter.
IEEE Transactions on Instrumentation and Measurement, 2000
Random interleaved sampling has become a widespread operating mode for digital storage oscillosco... more Random interleaved sampling has become a widespread operating mode for digital storage oscilloscopes. Different repetitions of (notionally) the same waveform are recorded at random time shifts and are interleaved in memory, resulting in an increase of the equivalent sampling frequency. This procedure requires substantial time, particularly if further averaging is required. In this paper, an approach that ensures accurate time shifts is presented for repeated waveform measurements. Operating two independent oscillators with related frequencies forms the accurate shifts. One of these is used to excite a waveform of interest repeatedly, and the other clocks the analog-to-digital converter (ADC). This architecture was implemented using a commercial "off-the-shelf" field programmable gate array. Examples of experimental waveforms, which are sampled at 2160 MHz using an ADC that is clocked at 80 MHz, are presented. They are compared with the simulated and independently measured waveforms where appropriate.
Self-Calibrating Scalable Research Platform for Ultrasonic Measurements in Chemical and Biological Reactors
ABSTRACT A research platform that integrates high accuracy FPGA waveform acquisition architecture... more ABSTRACT A research platform that integrates high accuracy FPGA waveform acquisition architectures and MATLAB graphical user interface is described. The platform provides self-calibrating measurements and frame jitter free operation. The FPGA architectures were tested on two different chips using the same user interface successfully. Examples of the platform utilization for monitoring of chemical and biological reactors are presented.
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Papers by Vladimir Ivchenko