Alojz Suhadolnik

Numerical calculation of digital curve length by using anchored discrete convolution

The paper presents a new method introducing an anchored discrete convolution for calculating the length of a digital curve. The method is based on discrete convolution by using convolution masks and point anchoring in the pixel. The use of ordinary convolution distorts the curve shape and gives large errors in length calculation. The advantage of anchoring is that it limits the point shifting into the pixel during the calculation of the curve length. The method is applied to an analytical arc and various calculations are performed. In addition different methods from the literature were compared and a real sample was tested.

Combined bracketing methods for solving nonlinear equations

Abstract Several methods based on combinations of bisection, regula falsi, and parabolic interpolation has been developed. An interval bracketing ensures the global convergence while the combination with the parabolic interpolation increases the speed of the convergence. The proposed methods have been tested on a series of examples published in the literature and show good results.

Refractive index measurement with optical fiber Mach-Zehnder interferometer

An interferometric technique for determination of the refractive index of liquids is described. The method is based on measurements of phase variations caused by the relative movement of an optical fiber tip in a liquid sample. The apparatus consists of two independent interferometers. A two-frequency Michelson interferometer is used to measure the liquid sample displacement in the air, while an optical fiber Mach-Zehnder interferometer measures the optical path length difference in the moving sample. The liquid sample refractive index is then derived by dividing the fringe counts obtained by both interferometers. The measurements have been performed in different liquids. With the distilled water sample, the statistical error of this method was found to be 5 X 10-5.

Superlinear bracketing method for solving nonlinear equations

A new method based on Mullers algorithm for solving nonlinear equations has been developed. The classic Mullers method is based on an interpolating polynomial built on the last three points of an iterative sequence. Unfortunately, Mullers method is not globally convergent. In order to ensure the global convergence a bracketing is introduced. The proposed method does not require the use of a derivative of the function and is more rapidly convergent than a classical regula falsi method. The method is good alternative to other bracketing methods.

Microphone based on fiber optic reflective sensor

A simple fiber optic microphone was developed. The sensor operates on the well known principle of reflective sensors where the optical fibers are used as a source and modulated light collecting medium. The optical fiber reflective sensor was applied as a vibration detector of a membrane isntrument. The sensor characteristic was found linear for displacement amplitudes up to 0.6 mm for the large core fiber optic sensor. The measured signals were compared to signals from a commercial dynamic microphone. The test results indicate that the fiber optic microphone is capable of detecting lower frequencies that the high quality dynamic audio microphone.