Sławomir Cięszczyk

Method of simultaneous measurement of two direction force and temperature using FBG sensor head

This paper presents a method for measuring two components of bending force and temperature using one sensor head. Indirect inference based on the spectra of two fiber Bragg gratings (FBGs) placed on a cantilever beam is used. The method was developed during work on the inverse problem of determining a nonuniform stress distribution based on FBG spectra. A gradient in the FBG stress profile results in a characteristic shape of its reflective spectrum. The simultaneous measurements of force and temperature were possible through the use of an appropriate layout of the sensor head. The spectral characteristics of the sensors gratings do not retain full symmetry, which is due to the geometry of the sensors head and the related difference in the distribution of the axial stress of the gratings. In the proposed approach, the change in width of the sum of the normalized transmission spectra was used to determine the value of the applied force. In the presented method, an increase in the sensitivity of this change to the force is obtained relative to the other known systems. A change in the spectral width was observed for an increase in bending forces from 0 to 150 N. The sensitivity coefficient of the spectral width to force, defined as the ratio of the change of the spectral half-width to the change in force was 2.6e-3  nm/N for the first grating and 1.2e-3  nm/N for the second grating. However, the sensitivity of the whole sensor system was 5.8e-3  nm/N, which is greater than the sum of the sensitivities of the individual gratings. For the purpose of this work, a station with a thermal chamber has been designed with a bracket on which fiber optic transducers have been mounted for use in further measurements. The sensor head in this experiment is considered to be a universal device with potential applications in other types of optical sensors, and it can be treated as a module for development through its multiplication on a single optical fiber.

Inverse problem of determining periodic surface profile oscillation defects of steel materials with a fiber Bragg grating sensor

We propose and experimentally demonstrate a method for the detection of steel material defects utilizing a fiber Bragg grating sensor. The considered defects are periodic grooves along the length of the tested steel profile. Direct measurement of the spectral reflectance characteristics of the fiber is performed, and the related inverse problem of indirect defect shape determination is solved. It has been demonstrated that the defect periodicity estimation is 2.5 mm, with an error of less than 0.1. Furthermore, it has been shown that for periodic intervals of the order of 5 mm, the difference between the strain amplitude calculated using our method and the amplitude obtained via the finite element method was 1.4 mϵ.

ECTL application for carbon monoxide measurements

Semiconductor lasers, which can be surely characterize by many of their advantages, have been used for measurements of concentration of gases for many years. Doing measurements in industrial conditions, because of its several difficulties, needs using special technology of measurements. In this article using modified, correlated absorption spectroscopy, in order to measure CO concentration, has been shown.

Application of flame monitoring system for flame spectrum analysis in industrial conditions

The flame monitoring system is intended to use in industrial condition for controlling pulverized coal combustion in power boiler. Placing the fiber-optic probes close to the each burner, one can obtain detailed information of the coal combustion process within the single burner. In order to enhance flame-monitoring system sensitivity for detection of fuels composition changes, we have measured flame emission spectra.

Passive optical gas concentration sensor in industrial boilers

This paper presents review of optical radiation measurement method in combustion process. Analysis and comparison of different methods is described and some applications in coal combustion boilers are shown. Such sensors can detect presence of target molecule, measure concentration ratio of two molecules and quantitatively measure the concentration.

Solving problems on base of concepts formalization of language image and figurative meaning of the natural-language constructs

Building of “clever” thesaurus by algebraic means on base of concepts formalization of language image and figurative meaning of the natural-language constructs in the article are proposed. A formal theory based on a binary operator of directional associative relation is constructed and an understanding of an associative normal form of image constructions is introduced. A model of a commutative semigroup, which provides a presentation of a sentence as three components of an interrogative language image construction, is considered.

Optical switching method based on two diffraction gratings bistable system

This paper presents properties of all-optical bistable fibre switch using two fibre Bragg gratings and rare earth elements doped optical fiber. It is not possible to obtain bistable properties at low switching power level in case of a single fibre grating. In this article the method of optical switching that uses all-optical switch has been proposed. It has been achieved by varying the refractive index of nonlinear optical material as a result of light signal amplitude changes. Presented optical bistable device can be used both in contemporary optically switched networks as well as in optoelectronic sensors, owing to their high achievable resolution.

A study and modeling of Fabry-Perot cavities with rare earth doped fiber

This paper presents properties of all-optical bistable fibre switch using two fibre Bragg gratings and rare earth elements doped optical fiber. It is not possible to obtain bistable properties at low switching power level in case of a single fibre grating. In this article the method of optical switching that uses all-optical switch has been proposed. It has been achieved by varying the refractive index of nonlinear optical material as a result of light signal amplitude changes. Presented optical bistable device can be used both in contemporary optically switched networks as well as in optoelectronic sensors, owing to their high achievable resolution.

The direct and inverse problem in fiber Bragg gratings modelling

In this article the proposals of the ways of modelling structures of fiber Bragg gratings by the use of the object-oriented programming and by the use of the direct and inverse problem were introduced. The results of the inverse problem solution, done for Bragg gratings, were also introduced in this work. This process was conducted by using of local optimization algorithms.

Neural network fusion and inversion model for NDIR sensor measurement

This article presents the problem of the impact of environmental disturbances on the determination of information from measurements. As an example, NDIR sensor is studied, which can measure industrial or environmental gases of varying temperature. The issue of changes of influence quantities value appears in many industrial measurements. Developing of appropriate algorithms resistant to conditions changes is key problem. In the resulting mathematical model of inverse problem additional input variables appears. Due to the difficulties in the mathematical description of inverse model neural networks have been applied. They do not require initial assumptions about the structure of the created model. They provide correction of sensor non-linearity as well as correction of influence of interfering quantity. The analyzed issue requires additional measurement of disturbing quantity and its connection with measurement of primary quantity. Combining this information with the use of neural networks belongs to the class of sensor fusion algorithm.