This article deals with the issue of fire safety monitoring of wooden buildings. Wooden buildings currently represent a quick and relatively inexpensive option for acquiring a family house. However, with regard to the building material and its flammability, the construction possibilities are strongly regulated by standards. The aim of this paper is to describe the possibilities of monitoring temperature changes during a simulated fire using optical fiber and a distributed temperature measurement system (DTS). The DTS system uses the principle of stimulated Raman scattering, which allows longitudinal temperature measurements with a spatial resolution of 1 m. The increase in spatial resolution was achieved by winding the optical fiber into 5 cm diameter rings, with a fiber length of 3 m in each ring. The measuring rings of optical fiber were attached to fabric arranged in a rectangular grid. This fabric with the rings was then placed at the surveyed locations in the construction panels. During the temperature loading of the test samples with the gas torch, temperature monitoring was carried out both on the reverse side of the samples and in the inner layers. The results showed that this system with conventional multimode optical fibers can measure temperatures ranging from 20 °C to approximately 500 °C. This method offers the possibility to accurately monitor the temperatures of wooden buildings, including the inner layers of the building panels. The proposed method can therefore be used to thoroughly verify the fire safety of wooden buildings and their components.
This article focuses on the analysis of the effect of long-time thermal load on the total losses of the selected fiber-optic couplers which have been thermal stressed for the thirty weeks at temperature 100 °C ± 5 °C. A total of six couplers with 10:90, 1:99 and 50:50 dividing ratio were tested. Measurements were made for two wavelengths (1310 nm and 1550 nm). The results obtained show how long-term thermal stresses affect the total losses of the optical couplers. This information could be interest for the practical implementations of the optical couplers.
The article describes a comparative measurement of a classical seismic sensor and a fiber-optic interferometric sensor for the perimetric applications. We created and proposed technically and financially the simplest interferometric sensor (type two-arm Mach Zehnder). A test polygon was created where were analyzed the vibration-acoustic manifestations caused by the 20 test subjects. The article describes original results that clearly point to the high sensitivity of the interferometric sensor.
Indirect monitoring of room's occupancy are two of the key requirements for technological systems that are used to secure independent housing for people in their home environment. For indirect monitoring of the Smart Home room's occupancy, we used Fiber Bragg grating sensor, temperature sensor T(°C), CO2(ppm) sensor, and humidity sensor rH (%). The first part of the paper describes the proposal of an implementation of Fiber Bragg grating for the detection of human presence in a room of SH. The second part of this paper dealing with the use of CO2 concentration measurement for detecting and monitoring room's occupancy with the implementation of Artificial Neural Network for the detection of human presence in the room of SH. Experimental results verified high method accuracy (<90%) within the short-term and long-term experiments. Utilization of Fiber Bragg grating in SH was proven on the experimental basis with the combination of measurement CO2 for room's occupancy monitoring in SH.
Road car transport is today the main species of cargo and passenger transport. However, car transport is accompanied by large negative effects with adverse environmental impacts. Therefore, it is an effort to shift part of the transported costs to rail transport. But the problem is vibrations which created the passing vehicles. The vibrations are transmitted over the rails and the railway infrastructure into the rock environment. These vibrations can adversely affect buildings around the railroad. This article presents a comparison of vibration measurements using a classical commonly used seismic sensor and innovative fiber-optic interferometric sensor. Presented results are based on the real measurements of train traffic. Presented results can serve as a basis for mathematical models which predict the future load of objects in the vicinity of railway tracks.
The undesirable dynamic effects of harmonic vibrations due to various devices and technologies are commonly monitored using by seismic stations operating on the principle of mechanical vibration systems (using on horizontal foundation structures or rock mass) or by resistance strain gauges (using e.g. on vertical concrete or steel elements). Modern, progressively evolving alternative to monitor these dynamic effects are methods based on fiber-optic principle. There is used fiber Bragg grating (FBG) or fiber-optic interferometric sensors. At the experimental level the article presents results comparison of conventional approaches to the monitoring of harmonic vibrations and approaches based on fiber-optic principle. Data was process in both amplitude and frequency domain.
Monitoring deformations of structures or testing of supporting elements are important activities in life cycle of structures. Determined large deformation may indicate defect or failure of supporting structures. The aim of the experiments is to show another, less frequently used strain measurement method. The fibber Bragg grating sensor was used for measuring of the strain changes in simple supported concrete beam. These sensors based on optical fibers allow to measure the strain of the fiber by changing the wavelength of light in the deformed fiber. The article describes an experiment conducted at the Faculty of Civil engineering VŠB Technical University of Ostrava. The values measured by these sensors are compared with measurements using traditional methods.
This paper deals with mechanical properties of polydimethylsiloxane (PDMS) as material for preparation of deformation sensors. PDMS is widely used especially in medical area. Some application of PDMS as material for preparation of deformation sensors with fiber optics has been prepared. Due to its hyper-elastic and viscoelastic of this material is complicate to use it with long time and large deformation mechanics. In this paper authors compare the numerical models of prepared sensor using hyper-elastic models and mechanical experiment at large deformation.
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