Vojtech Kresalek

Classification of audio sources using neural network applicable in security or military industry

In this paper, classification of audio sources is presented to supplement current work on existing system for localization of audio sources. The question of achieving the audio classification lies in the convenient discrimination of the feature vector in the feature vector space. Characteristics based on frequency analysis were chosen and used as feature vector. Artificial neural network was applied in order to classify different audio classes especially from security and military areas, such as different shots and explosions. The information about specific type of a sound can trigger localization process of given audio source. Moreover, it can improve situation when guards get ready for the alert state. This classification method is currently developed as an additional part of the system for audio source hyperbolic localization; the paper also gives some basic structure of that system. Its utilization can be found for additional securing of larger objects like squares or military basis, for instance.

Utilization of audio source localization in security systems

Paper deals with utilization of audio source localization in security systems especially dedicated for additional securing of larger objects like squares or military basis for instance. Proposed detection system supposes that intruder makes uniquely determinable noise which can be picked up by microphone array. On the basis of real-time signal analysis from each microphone unit direction to acoustic source can be determined. In this paper is presented time-delay estimation method of the direction of arrival of the sound wave which is used in many other practical applications. Experimental part proposes design of the evaluation system consisting of microphone sensory system and standard personal computer equipped with Advantech PCI-1716 multifunction data acquisition card.

The effect of tip speed in AFM scratching

In this study, we investigated the effect of tip speed in AFM scratching. Three testing patterns were engraved on polycarbonate substrate at different scratching parameters. The subsequent characterization of fabricated structures was performed using the identical atomic force microscope. It was found that the depth and width depend only weakly on tip speed.

Scanning of electromagnetic radiation for EMC and data security purposes

A semi-automatic measurement system and diagnostic tool for localization of radiating parts of electronic devices in near-field was developed. A near-field scanning of electromagnetic emission is performed by the system. Maximal spatial resolution of the scanning is 0.2 mm which is sufficient for exact localization of radiating parts in the most cases. Frequency range of the measurement is from 30 MHz to 3 GHz. The advantage of the system is simplicity of implementation, as it is based entirely on commercially produced devices. The test receiver Rohde & Schwarz ESPI7 was used for the measurement of radiation level. The advantageous functions of the receiver such as fast frequency scan and simultaneous measurement with three detectors was utilized. The scanning procedure is controlled by a program which leads a user throughout all measurement steps. The program was made in Agilent VEE Pro. Important part of the measurement is processing of the measured data. Therefore, software for effective data visualization and analysis was developed. The key functions of the program are projection of the measured data on a photograph of the tested device, peak search and highlighting of critical places. Results of the scanning of a main board of a personal computer are presented.

The effect of scratching direction in AFM nanolithography

In this paper, we investigated the effect of scratching direction in AFM scratching. The understanding of this effect is one of the key factors in the patterning process. In our experiment, several testing grooves were engraved in all four basic directions (forward, backward, right and left) on polycarbonate substrate using Si probe. Both the fabrication and subsequent characterization were performed using the identical atomic force microscope. Our results were compared to previous reports. It was found that scratching in the backward direction is the most suitable for the common usage.

Nano-steganography using atomic force microscopy

This paper presents physical nano-steganography for secret data transmission. The experimental code was engraved into the base polycarbonate plastic layer of a compact disc by atomic force microscopy nanolithography. The advantage is that such information cannot be found using optical microscopes and it is very problematic to find it even by the most of electron microscopes due to the subtle variations in height.

Terahertz Time-Domain Spectroscopy for Studying Absorbable Hemostats

This study deals with the kinetics of absorbable hemostats used for supporting the hemostasis and wound closure during surgical intervention. There are several types of hemostats of different composition therefore with different mechanism of action. Here, terahertz (THz) time-domain spectroscopy is used for studying the absorption kinetics of the reactions between the hemostatic and the physiological saline solution (PSS). The reactions correspond with the changes of the THz radiation response measured in time. These time dependences are analyzed to find time constants for mathematical description of the hemostatic kinetics and the significant differences among all types of hemostats are found. The physiological saline solution is replaced by human blood in the additional measurement. Based on the results, we can compare the reaction rate of different types of hemostats that could be beneficial in the surgery practice.

Quality control in microelectronics using scanning probe microscopy

In this paper, atomic force microscopy and its variation scanning microwave microscopy were used for the characterization of microelectronics (PNP bipolar transistors on a chip and epitaxial layers with different properties on a silicon substrate). The capabilities of these methods in the quality control process are presented.

Nanoscale characterization of ultra-thin tungsten films deposited by radio-frequency magnetron sputtering

In this article, atomic force microscopy was used for nanoscale characterization of ultra-thin tungsten films which were deposited on silicon substrate. Radio-frequency magnetron sputtering was used for tungsten deposition on the surface.

Device design based on automatic colour measurement used for polymer waste recycling

This paper deals with design and development of a device used for measurement of colour changes of granulate polymer material which is produced by recycling technology. Individual parts of design from the point of hardware and software are described. Description of user application in MATLAB programming environment is introduced. Relative measurement of reference sample set is also presented.