Search Results

You are looking at 1 - 4 of 4 items for :

  • Author: Michał Nowicki x
  • Engineering x
Clear All Modify Search
Open access

Michał Nowicki, Maciej Kachniarz and Roman Szewczyk

Abstract

The paper presents a special measurement system for investigation of temperature influence on the indication of commercially available sensors of the magnetic field. Utilizing the developed system, several magnetoresistive and Hall-effect sensors were investigated within the temperature range from −30°C to 70°C. The obtained results indicate that sensitivity of most of the investigated sensors is unaffected, except the basic magnetoresistive device. However, Hall-effect sensors exhibit considerable temperature drift, regardless of the manufacturer.

Open access

Piotr Karwat, Ziemowit Klimonda, Michał Sęklewski, Marcin Lewandowski and Andrzej Nowicki

Abstract

Ultrasonic methods of human body internal structures imaging are being continuously enhanced. New algorithms are created to improve certain output parameters. A synthetic aperture method (SA) is an example which allows to display images at higher frame-rate than in case of conventional beam-forming method.

Higher computational complexity is a limitation of SA method and it can prevent from obtaining a desired reconstruction time. This problem can be solved by neglecting a part of data. Obviously it implies a decrease of imaging quality, however a proper data reduction technique would minimize the image degradation.

A proposed way of data reduction can be used with synthetic transmit aperture method (STA) and it bases on an assumption that a signal obtained from any pair of transducers is the same, no matter which transducer transmits and which receives. According to this postulate, nearly a half of the data can be ignored without image quality decrease.

The presented results of simulations and measurements with use of wire and tissue phantom prove that the proposed data reduction technique reduces the amount of data to be processed by half, while maintaining resolution and allowing only a small decrease of SNR and contrast of resulting images.

Open access

Przemysław Łabęcki, Michał Nowicki and Piotr Skrzypczyński

Abstract

This article considers selected operational characteristics and measurement errors of the 2D laser scanner URG-04LX, which is a compact sensor suitable for walking robots. Quantitative errors in range measurement are evaluated considering the intensity output available from the sensor. The obtained intensity values help to correct the range measurements with regard to the optical characteristics of the observed surfaces. Moreover, mixed measurements are characterized and compared to the mixed measurements characteristics in the popular Sick LMS 200 laser scanner. Finally, it is shown how taking into account the error characteristics of the URG-04LX scanner improves its performance as the main exteroceptive sensor of a small walking robot.

Open access

Barbara Gambin, Michał Byra, Eleonora Kruglenko, Olga Doubrovina and Andrzej Nowicki

Abstract

Texture of ultrasound images contain information about the properties of examined tissues. The analysis of statistical properties of backscattered ultrasonic echoes has been recently successfully applied to differentiate healthy breast tissue from the benign and malignant lesions. We propose a novel procedure of tissue characterization based on acquiring backscattered echoes from the heated breast. We have proved that the temperature increase inside the breast modifies the intensity, spectrum of the backscattered signals and the probability density function of envelope samples. We discuss the differences in probability density functions in two types of tissue regions, e.g. cysts and the surrounding glandular tissue regions. Independently, Pennes bioheat equation in heterogeneous breast tissue was used to describe the heating process. We applied the finite element method to solve this equation. Results have been compared with the ultrasonic predictions of the temperature distribution. The results confirm the possibility of distinguishing the differences in thermal and acoustical properties of breast cyst and surrounding glandular tissues.