Long-term structural health monitoring (SHM) plays an important role in the safety of public transport infrastructure such as bridges or tunnels and warns in the event of any emerging problem. This ...article describes development and testing of system based on fiber Bragg grating (FBG) sensors that can detect changes in strain and temperature. The first phase of the research has been focused on the development of new fiber optic sensors for the monitoring of concrete structures and their investigation in laboratory conditions. The work also shows novel applicability of the same FBG technology for glulam structures. Mechanical loading tests of the concrete beam as well as glulam beam with embedded sensors were carried out. Data measured by developed fiber optic sensors were compared with the readings from reference sensors as well as with the analytically calculated values. The achieved results proved good agreement between the measured data, analytical data and reference methods. In second phase of the research, the pilot installation of the sensors was carried out on the newly constructed prestressed-concrete bridge. The bridge was monitored throughout pre-stressing phase and monitoring continued after the completion of the construction works. Problems with the fragility of the sensors occurred during the measurements, but the obtained results provide a good basis for further improvement of the system.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This thesis provides concise and comprehensive overview of two different methods of fibre optic sensing and their beneficial use in geotechnical monitoring: Brillouin Optical Time Domain Analysis ...(BOTDA) and Fibre Bragg Gratings (FBG). The technological development of optical fibres and methods of optical fibre sensing led to the creation of new optic sensors used in civil engineering is last decades. The optic fibre sensing technology is in principle suitable for all kinds of building structures; it can be used for buildings, roads, bridges or tunnels and also for monitoring in geotechnics. Additionally, considering geotechnical structures, due to high uncertainties in the design parameters, it is desirable to collect in-situ data to verify the design assumptions, construction quality and actual behaviour in service. As visual inspection and surface mounted sensors are mostly inapplicable for this task, embedded fibre optic sensors may be a suitable monitoring solution for foundations, piles, anchors, tunnels, embankments as well as natural slopes. In the theoretical part of the thesis, the basic principles of both BOTDA and FBG sensing technologies are explained and followed by the state-of-the-art reviews. The practical part presents selected laboratory tests and mainly is focused on real on-site applications of BOTDA and FBG. The wide range of applications regarding geotechnical monitoring is shown in several field tests. The optical fibre sensing was used to observe slope movements both in deep boreholes in order to identify the shear zone in the subsoil / bedrock and in shallow trenches for monitoring of shallow active zones; the BOTDA technology was used for monitoring of deformations of tunnel primary lining. The FBG sensing technology was used for determination of the ground anchor root resistance mobilization, as well as during the static load test of diaphragm wall's lamellae for strain measurement. Each field test is described, the monitoring motivation is presented, details about the sensors are provided and the results are discussed.
Fiber Bragg Grating (FBG) sensors are used worldwide in structural health monitoring as a highly effective strain sensing method. Compared to traditional strain sensing methods in geotechnics, such ...as measurement by extensometers, deformeters, or strain gauges, FBG technology is beneficial in many issues, such as small dimensions of the sensor, easy and fast installation, long-term stability, immunity to electromagnetic interference or possibility of having dozens of sensing points on a single measuring cable. One part of the D3 highway construction, connecting the capital city Prague with southern Bohemia, is Pohůrka tunnel in the suburbs of the city of České Budějovice. With regard to the geomorphology of the locality and directional and elevational design of the highway, the tunnel is designed to be cut and cover. It has two 995.5 m long tubes, guided in two opposing curves. Due to complicated geotechnical and hydrogeological conditions in combination with demanding construction, static load tests of selected individual lamellae of diaphragm walls designed as retaining, load-bearing as well as sealing structures of the cut and cover tunnel were planned. Two test lamellae were instrumented for the purpose of static load test by resistance strain gauges, as well as FBG sensors. After the load tests, the results from both measurement technologies were compared to each other. The differences between the values obtained from FBG sensors and the values from strain gauges are acceptable enough; both measuring technologies proved their suitability in static load test of a diaphragm walls.
The condition of underlying rock and footing masonry affects significantly technical condition of historical monuments. The caused subsidence may affect the origin of construction cracks, which may ...directly influence its stability. These impacts are mostly indirect and they are difficult to identify due to information lack. Footing masonry and long-term changes in the underlying rock are hidden underneath existing ground and floor level. If records related to foundations do exist, they are frequently fragmental. Monitoring can be source of information due to direct outputs and data describing footing masonry and subsoil conditions. Examples of monitoring instrumentation and gained results, determination of conditions of masonry together with principles of monitoring applied in the project focused on the Broumov Group of Churches are presented in the paper. Within the monitoring instrumentation, Fibre Bragg Gratings monitoring technology has been used and is described in the paper as well.
Recently, there has been an increased interest in structural health monitoring (SHM) of building and transport structures. Standard strain gauges placed on a beam surface are mostly used to monitor ...the mechanical stresses of timber or concrete structures. However, these sensors are susceptible to mechanical damage, electromagnetic interference or negative influences of the measured data during the measurement, such as temperature variations or potential loss of data due to explosive environment. The fibre optic sensor system offers a more suitable and reliable solution – the sensors can be integrated directly into the load bearing structure during its production and thus protected by the construction material against ambient environmental conditions. The first part of this paper presents series of environmental tests of a measuring system based on Fibre Bragg Grating principle performed from 2016 to 2018 in a climate chamber. The chamber can generate defined humidity and/or temperature cycles, which can simulate the behavior of the structure under real environmental conditions. The tested fibre optic sensor system is suitable for load bearing timber (glued laminated timber beams) and concrete structures. In the second part of this paper, mechanical loading tests of glued laminated timber beam with integrated fiber optic sensors performed in 2016, 2017 and 2018 are presented. The article describes the design of test cycles, gives the results of testing, and is concluded with the discussion of given results together with the outline of the future research directions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The paper presents a concept of Fiber Bragg Grating sensors and Brillouin Optical Time Domain Reflectometry application for deformation monitoring on a side slope of an open cast mine. The fiber ...optics measurement techniques, instruments of our own construction and methods of instrumentations developed within two past research projects were used in-situ. Different means of geotechnical instrumentation for subsoil deformation monitoring were installed in a former opencast-mine in the Czech Republic in order to test our instrumentations and to gather information about the mine slope behavior. The first type is the sub-surface monitoring of the potentially unstable area and the second one is performed in boreholes to determine a slip surface location and to describe deformation development in time. The instrumentations were done both with fiber optics and geotechnical deformation measurement tools, so that the results can be cross-checked. Deployment and critical points of fiber optics deformation sensing as well as advantages and disadvantages are indicated and evaluated.
The paper introduces selected results of applications fiber optics deformation monitoring in geotechnics. Series of Fiber Bragg Gratings sensors and Brillouin Optical Time Domain Analysis were used ...for monitoring of a side slope deformations of an open cast mine. These monitoring technologies with developed ways of protection of fibers/optic cables, installation procedures and data evaluation were tested under laboratory conditions and in the underground research center of the Czech Technical University in Prague prior to on site deployment. The first type of applications was used for the surface monitoring of the potentially unstable area installed just below the ground surface. The outputs of these applications were the determination of the active part in the monitored area, the deformation development in time in selected lines drawn through the potentially unstable areas. The check of the assumption of so called reference part of the installation was provided with use of the Global Navigation Satellite System, which is sufficiently accurate for larger deformations.
In the past few years, the authors of the paper were involved in the research project focused on the application of Brillouin Optical Time Domain Analysis (BOTDA) for distributed deformation ...measurement in geotechnics. The basic principles of the BOTDA method as well as the process of its laboratory testing, on site applications and development of necessary instruments of own construction have been already published in various literatures. The paper presents development of reliable process for association of BOTDA analyzer outcomes and the optical measuring track in the geotechnical structure or in the host environment of the structure. The topography of the sensing cable allows obtaining possible critical spots of the structure and modeling of its behavior. The paper shows different possible ways of gaining the sensing cable topography. This process is relevant for various geotechnical structures and environments such as retaining structures, potentially unstable slopes or tunnels and several examples of its realization are listed and described in the paper.
Nanofibrous materials produced from natural polymers have wide range of potential uses in regenerative medicine. This paper focuses on preparation of nanofibrous layers produced from intentionally ...hydrophobized derivatives of hyaluronan, which is known for its ability to promote wound healing. This structural modification of hyaluronan expands the range of potential uses of this promising material, which is otherwise limited due to the hydrophilic nature of hyaluronic acid. The aim of this research was preparation of nanofibrous material that would retain its fibrous structure and dimensional stability even after getting into contact with an aqueous medium, which is impossible to achieve with layers composed solely of native hyaluronan. As a result, such material would be able to retain its breathability and good mechanical properties when both dry and wet. Furthermore, all prepared materials were proved non-toxic for cells. This self-supporting nanofibrous matrix can be used as a scaffold, or porous wound dressing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
10.
Eye involvement of borrelia aetiology Krbková, Lenka; Vodicková, Kristýna; Pellarová, Hana ...
Klinicka mikrobiologie a infekcni lekarstvi
13, Issue:
3
Journal Article
Peer reviewed
We present a case of eye involvement -- intermediate uveitis -- during tick-borne borreliosis in a 10-year-old boy. Ophthalmologic examination revealed impaired vision, apparent thick floating ...whitish opacity in the vitreous humour of the left eye and fine fibres in the vitreous humour of the right eye. Sonographic examination confirmed hyperechogenic opacity in the vitreous humour. An autoimmune process was suspected but not confirmed. Serological examination showed IgG antibodies against three pathogenic borreliae and borderline values of IgM antibodies against Borrelia garinii were found by immunoblot. The boy was treated with intravenous ceftriaxone for 21 days. The subsequent sonographic examination showed only minute sporadic echogenicity. Biomicroscopically, only residual opacity in the vitreous humour was found. Isolated eye involvement of borrelia aetiology is rare. The discussion provides a review of similar cases of uveitis including diagnosis of the eye form as published in literature.
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