Marko Barjaktarović

First steps in new affordable PIV measurements

Particle image velocimetry (PIV) is an optical, laser based, measurement of fluid velocity and its 2D/3D visualisation. We have presented a new approach in low-cost PIV design using: 1) fast industrial camera, 2) laser pointer, with cylindrical lens for continual fluid flow illumination, 3) acquisition software developed in house, 4) OpenPIV analysis software. Velocity was measured in the glass jar where swirl flow was generated by magnetic stirrer. In this pilot study, results obtained by calibration device based on Laser Doppler anemometry and our PIV results are in good agreement.

Wavelet based edge detection algorithm for web surface inspection of coated board web

This paper presents significant improvement of the already installed vision system. System was designed for real time coated board inspection. The improvement is achieved with development of a new algorithm for edge detection. The algorithm is based on the redundant (undecimated) wavelet transform. Compared to the existing algorithm better delineation of edges is achieved. This yields to better defect detection probability and more accurate geometrical classification, which will provide additional reduction of waste. Also, algorithm will provide detailed classification and more reliably tracking of defects. This improvement requires minimal changes in processing hardware, only a replacement of the graphic card would be needed, adding only negligibly to the system cost. Other changes are accomplished entirely in the image processing software.

High performance coated board inspection system based on commercial components

This paper presents a vision system for defect (fault) detection on a coated board developed using three industrial firewire cameras and a PC. Application for image processing and system control was realized with the LabView software package. Software for defect detection is based on a variation of the image segmentation algorithm. Standard steps in image segmentation are modified to match the characteristics of defects. Software optimization was accomplished using SIMD (Single Instruction Multiple Data) technology available in the Intel Pentium 4 processors that provided real time inspection capability. System provides benefits such as: improvement in production process, higher quality of delivered coated board and reduction of waste. This was proven during successful exploitation of the system for more than a year.

Hybrid Vision-Fusion system for whole-body scintigraphy

Radioiodine therapy in the treatment of differentiated thyroid carcinoma (DTC) is used in clinical practice for the ablation of thyroid residues and/or destruction of tumour tissue. Whole-body scintigraphy for visualization of the spatial 131I distribution performed by a gamma camera (GC) is a standard procedure in DTC patients after application of radioiodine therapy. A common problem is the precise topographic localization of regions where radioiodine is accumulated even in SPECT imaging. SPECT/CT can provide precise topographic localization of regions where radioiodine is accumulated, but it is often unavailable, especially in developing countries because of the high price of the equipment. In this paper, we present a Vision-Fusion system as an affordable solution for 1) acquiring an optical whole-body image during routine whole-body scintigraphy and 2) fusing gamma and optical images (also available for the auto-contour mode of GC). The estimated prediction error for image registration is 1.84u202fmm. The validity of fusing was tested by performing simultaneous optical and scintigraphy image acquisition of the bar phantom. The fusion result shows that the fusing process has a slight influence and is lower than the spatial resolution of GC (mean valueu202f±u202fstandard deviation: 1.24u202f±u202f0.22u202fmm). The Vision-Fusion system was used for radioiodine post-therapeutic treatment, and 17 patients were followed (11 women and 6 men, with an average age of 48.18u202f±u202f13.27 years). Visual inspection showed no misregistration. Based on our first clinical experience, we noticed that the Vision-Fusion system could be very useful for improving the diagnostic possibility of whole-body scintigraphy after radioiodine therapy. Additionally, the proposed Vision-Fusion software can be used as an upgrade for any GC to improve localizations of thyroid/tumour tissue.

Simulating fluid flow in “Shrinky Dink” microfluidic chips — Potential for combination with low-cost DIY microPIV

This paper describes the first steps towards a union of low-cost “Shrinky Dink” (SD) microfluidic chip fabrication with low-cost do-it-yourself (DIY) micro-PIV. The SD microfluidic chip fabrication technique enables rapid development of complex designs using inexpensive materials and reagents, while abrogating the need for a cleanroom. DIY microPIV system provides a low-cost means of accurate flow profile analysis in microchannels, comparable to high-cost, standard microPIV setups. Initially, a simple microfluidic design of a T-junction was created and several chips with the same design were fabricated by the SD technique. We used COMSOL Multiphysics Creeping Flow interface to simulate the flow profiles in the obtained channel geometry. The next step will be to experimentally verify these simulations using our DIY microPIV system, in order to confirm the potential of combined use of these two cost-effective systems, to rapidly produce and analyze microfluidic designs, thereby enabling greater accessibility to these methods in labs with limited resources. It is envisioned that the systems described here can be effectively employed for a wide array of applications in biophysics, fluid mechanics, and bioengineering.

Analog front end stage of a fiber optic magnetic field point scanner

Fiber optic Faraday magnetic field scanners are sophisticated sensing devices whose important part is electronic signal processing block. This paper presents some aspects of a design of an AFE (Fig. 2) for FOFMS that meets these requirements. Electronic section containing the AFE has been constructed and implemented into electronic processing section containing analog to digital conversion (ADC). This unit has been integrated into a sensor and used to collect and process data in order to asses the sensor performance figures.

High input impedance ADC driver with error compensation

A novel high impedance JFET high voltage follower combined with ADC driver and a dedicated error compensation feedback is discussed in this paper. Proposed circuit builds around required ADC driver and its transfer curve by adding few low cost components to turn it into a high impedance input ADC driver with high voltage capability and error compensation ability. Such a circuit is applicable in instrumentation dedicated to voltage measurement.