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Journal articles on the topic 'C-OTDR monitoring'
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Zhang Xuping, 张旭苹, 陈晓红 Chen Xiaohong, 梁蕾 Liang Lei та ін. "长距离海缆在线监测改进型C-OTDR系统". Acta Optica Sinica 41, № 13 (2021): 1306001. http://dx.doi.org/10.3788/aos202141.1306001.
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Liu, Pengfei, Minglei Ma, Jianxiu Wang, Yanxia Long, Ansheng Cao, and Huboqiang Li. "Shield tunnel leakage detection using distributed optical fiber." IOP Conference Series: Earth and Environmental Science 1337, no. 1 (2024): 012008. http://dx.doi.org/10.1088/1755-1315/1337/1/012008.
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Abstract Leakage in operating tunnels is a serious problem during operating stage. In order to realize non-destructive detection of leakage in an operating shield tunnel, an optical fiber temperature measurement method based on Raman scattering and infrared thermal imaging technology is developed. The working principle of leakage monitoring with Distributed Fiber Optic Temperature Sensor (DTS) combined with time domain reflectometry (OTDR) technology are introduced. The distributed measurement of temperature field is realized in a typical tunnel. Infrared thermal imager is used to perform thermal imaging on the leakage area, and the temperature difference between the leakage area and the non-leakage area is 3.6 °C, which can meet the requirements of distributed optical fiber side leakage temperature accuracy. This illustrates the feasibility of quantitative monitoring of leaks in distributed optical fiber temperature sensing systems. The reasonable arrangement of leakage monitoring fiber in distributed fiber temperature sensing system is discussed in practical engineering.
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Timofeev, Andrey V. "A Non-Asymptotic Confidence Region with a Fixed Size for a Scalar Function Value: Applications in C-OTDR Monitoring Systems." Open Journal of Statistics 04, no. 08 (2014): 578–85. http://dx.doi.org/10.4236/ojs.2014.48054.
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Gan, Weibing, Shiyu Tu, Yuan Tao, Lingyun Ai, Cui Zhang, and Jianguan Tang. "Opto-Mechatronics System for Train-Track Micro Deformation Sensing." Sensors 22, no. 1 (2021): 296. http://dx.doi.org/10.3390/s22010296.
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In this paper, we proposed and experimentally demonstrated an opto-mechatronics system to detect the micro-deformation of tracks caused by running trains. The fiber Bragg grating (FBG) array acting as sensing elements has a low peak reflectivity of around −40 dB. The center wavelengths were designed to alternate between 1551 nm and 1553 nm at 25 °C. Based on dual-wavelength, wavelength-division multiplexing (WDM)/time-division multiplexing (TDM) hybrid networking, we adopted optical time-domain reflectometry (OTDR) technology and a wavelength-scanning interrogation method to achieve FBG array signal demodulation. The field experimental results showed that the average wavelength shift of the FBG array caused by the passage of the lightest rail vehicle was −225 pm. Characteristics of the train-track system, such as track occupancy, train length, number of wheels, train speed, direction, and loading can be accurately obtained in real time. This opto-mechatronics system can meet the requirements of 600 mm spatial resolution, long distance, and large capacity for monitoring the train-track system. This method exhibits great potential for applications in large-scale train-track monitoring, which is meaningful for the safe operation of rail transport.
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Kochanowicz, Marcin, and Jakub Markiewicz. "Application of optical reflectometer for monitoring corrosion process." Photonics Letters of Poland 14, no. 2 (2022): 40. http://dx.doi.org/10.4302/plp.v14i2.1144.
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In this work, a corrosion sensor based on an optical time domain reflectometer was presented. The first sensor with a bare tip was used to measure the corrosion process of silica glass fiber. Another sensor with a deposited silver layer was used for monitoring the corrosion process in nitric acid. In both cases, reflectance at the end of the fiber was decreasing with immersion time. Thus we can describe the corrosion stage by the level of fresnel reflectance. The maximum sensitivities of the analyzed sensors were as follows: 0.7dB/min (3% HF solution) 0.15dB/h (5%HNO3 solution) Results showed that the corrosion process in all cases wasn’t fully linear, and all reactions began almost instantly after immersing sensors in tested corrosive environments. Full Text: PDF ReferencesC. Elosua, F.J. Arregui et al., "Micro and Nanostructured Materials for the Development of Optical Fibre Sensors", Sensors, 17, 2312 (2017). CrossRef B.H. Lee, Y.H. Kim et al., "Interferometric Fiber Optic Sensors", Sensors, 12, 2467 (2012). CrossRef X. Wang, O.S. Wolfbeis, "Fiber-Optic Chemical Sensors and Biosensors" (2013-2015), Analytical Chemistry, 88, 203 (2016). CrossRef M.A. Butler, "Fiber Optic Sensor for Hydrogen Concentrations near the Explosive Limit", J. Electrochem. Soc., 138, 46 (1991). CrossRef M.A. Butler, "Optical Fiber hydrogen sensor", Appl. Phys. Lett. 45, 1007 (1984). CrossRef S.F. Silva, L. Coelho et al., "A Reviev of Palladium-Based Fiber-Optic Sensors for Molecular Hydrogen Detection", IEEE Sens. J., 12, 93 (2012). CrossRef C. Floridia, F.C. Salgado et al., "Methane leak detection and spectral analysis by using only optical time domain reflectrometry in semidistributed remote optical sensors", IEEE Sens., 2016. CrossRef J.F. Martins-Filho, E. Fontana et al., Fiber-optic-based Corrosion Sensor using OTDR, IEEE SENSORS 2007 Conference (2007). CrossRef E.A. Lima, A.C. Bruno, "Improving the detection of Flaws in Steel Pipes Using SQUID Planar Gradiometers", IEEE Trans. Appl. Supercond. 11, 1299 (2001). CrossRef J. Yin, J. Pineda de Gyvez et al., "Real-Time Full Signature Corrosion Detection of Underground Casing Pipes", IEEE Instrumentation and Measurement Technology Conference (1996). CrossRef H. Park, D. Kim et al., "HF etched glass substrated for improved thin-film solar cells", Heliyon, 4, 10, (2018). CrossRef M. Mozammel, "Kinetics of Silver Dissolution in Nitric Acid from Ag-Au0:04-Cu0:10 and Ag-Cu0:23 Scraps", J. Mater. Sci. Technol., 22, 696 (2006). DirectLink
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EOM, T. J. "Temperature Monitoring System Based on Fiber Bragg Grating Arrays with a Wavelength Tunable OTDR." IEICE Transactions on Electronics E88-C, no. 5 (2005): 933–37. http://dx.doi.org/10.1093/ietele/e88-c.5.933.
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Polishchuk, N. M., D. L. Kyryk, and I. Ye Yurchuk. "Microbiological monitoring as a component of efficient prevention and treatment of purulent-septic infections in an orthopedics and traumatology department." Zaporozhye Medical Journal 23, no. 3 (2021): 381–87. http://dx.doi.org/10.14739/2310-1210.2021.3.229667.
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Efficient monitoring of circulating purulent-septic infectious agents in a clinical setting and a study on antibiotic susceptibility of isolated strains of microorganisms allows identifying changes in the pathogen structure and trends in antibiotic resistance development, which helps to determine the tactics of antibacterial therapy and elaborate appropriate measures. The aim of the study. Retrospective analysis of the results of microbiological monitoring of purulent-septic infectious (PSI) agents in the Orthopedics and Traumatology Department (OTD) of the Zaporizhzhia Central Ambulance and Emergency Care Hospital over the period 2017–2020 to determine the main antibacterial drugs for empirical therapy. Materials and methods. We analyzed the bacteriological test results of 664 clinical material samples obtained from OTD patients using bacteriological examination statistical reporting and analytical data of the WHONET 5.6 software. Results. The main PSI pathogens in the OTD were from the ESKAPE group: E. coli, S. aureus, K. pneumoniae, A. baumannii, E. faecalis, P. aeruginosa and S. epidermidis, P. mirabilis, C. amycolatum. Isolates of E. faecalis were sensitive to vancomycin, linezolid, S. aureus – to linezolid, tigecycline, netilmicin, A. baumannii – to tigecycline. All P. aeruginosa strains were resistant to ticarcillin/clavulanate, cefepime, chloramphenicol, imipenem, meropenem, aztreonam, ciprofloxacin. E. coli and K. pneumoniae were resistant to ampicillin, ticarcillin/clavulanate, aztreonam, ceftriaxone, cefepime. The number of isolates sensitive to piperacillin/tazobactam, carbapenems, levofloxacin, gentamicin, amikacin, chloramphenicol ranged from 37 % to 65 %. Conclusions. E. coli, S. aureus, K. pneumoniae, A. baumannii, E. faecalis, P. aeruginosa, S. epidermidis, P. mirabilis, C. amycolatum play an important role in the structure of PSI pathogens in the Orthopedics and Traumatology Department of Zaporizhzhia Central Ambulance and Emergency Care Hospital. The antibiotics of choice as the antibacterial empirical therapy for enterococcal infections are vancomycin, linezolid, for staphylococcal infections – vancomycin, linezolid, tigecycline, netilmicin. PSI pathogens continually evolve developing antibiotic resistance, and it is of particular importance to monitor antibiotic susceptibility of microorganisms within the OTD.
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He, Yanfeng, Hossain Mohammed Syedul Hoque, and Kengo Sudo. "Introducing new lightning schemes into the CHASER (MIROC) chemistry–climate model." Geoscientific Model Development 15, no. 14 (2022): 5627–50. http://dx.doi.org/10.5194/gmd-15-5627-2022.
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Abstract. The formation of nitrogen oxides (NOx) associated with lightning activities (hereinafter designated as LNOx) is a major source of NOx. In fact, it is regarded as the dominant NOx source in the middle to upper troposphere. Therefore, improving the prediction accuracy of lightning and LNOx in chemical climate models is crucially important. This study implemented three new lightning schemes with the CHASER (MIROC) global chemical transport and climate model. The first lightning scheme is based on upward cloud ice flux (ICEFLUX scheme). The second one (the original ECMWF scheme), also adopted in the European Centre for Medium-Range Weather Forecasts (ECMWF) forecasting system, calculates lightning flash rates as a function of QR (a quantity intended to represent the charging rate of collisions between graupel and other types of hydrometeors inside the charge separation region), convective available potential energy (CAPE), and convective cloud-base height. For the original ECMWF scheme, by tuning the equations and adjustment factors for land and ocean, a new lightning scheme called the ECMWF-McCAUL scheme was also tested in CHASER. The ECMWF-McCAUL scheme calculates lightning flash rates as a function of CAPE and column precipitating ice. In the original version of CHASER (MIROC), lightning is initially parameterized with the widely used cloud-top height scheme (CTH scheme). Model evaluations with lightning observations conducted using the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) indicate that both the ICEFLUX and ECMWF schemes simulate the spatial distribution of lightning more accurately on a global scale than the CTH scheme does. The ECMWF-McCAUL scheme showed the highest prediction accuracy for the global distribution of lightning. Evaluation by atmospheric tomography (ATom) aircraft observations (NO) and tropospheric monitoring instrument (TROPOMI) satellite observations (NO2) shows that the newly implemented lightning schemes partially facilitated the reduction of model biases (NO and NO2), typically within the regions where LNOx is the major source of NOx, when compared to using the CTH scheme. Although the newly implemented lightning schemes have a minor effect on the tropospheric mean oxidation capacity compared to the CTH scheme, they led to marked changes in oxidation capacity in different regions of the troposphere. Historical trend analyses of flash and surface temperatures predicted using CHASER (2001–2020) show that lightning schemes predicted increasing trends of lightning or no significant trends, except for one case of the ICEFLUX scheme, which predicted a decreasing trend of lightning. The global lightning rates of increase during 2001–2020 predicted by the CTH scheme were 17.69 % ∘C−1 and 2.50 % ∘C−1, respectively, with and without meteorological nudging. The un-nudged runs also included the short-term surface warming but without the application of meteorological nudging. Furthermore, the ECMWF schemes predicted a larger increasing trend of lightning flash rates under the short-term surface warming by a factor of 4 (ECMWF-McCAUL scheme) and 5 (original ECMWF scheme) compared to the CTH scheme without nudging. In conclusion, the three new lightning schemes improved global lightning prediction in the CHASER model. However, further research is needed to assess the reproducibility of trends of lightning over longer periods.
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Andrey, V. Timofeev. "Adaptive Nonparametric Approach for Guaranteed Real-Time Detection of Targeted Signals in Multichannel Monitoring Systems." May 2, 2015. https://doi.org/10.5281/zenodo.1105731.
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An adaptive nonparametric method is proposed for stable real-time detection of seismoacoustic sources in multichannel C-OTDR systems with a significant number of channels. This method guarantees given upper boundaries for probabilities of Type I and Type II errors. Properties of the proposed method are rigorously proved. The results of practical applications of the proposed method in a real C-OTDR-system are presented in this report.
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Andrey, V. Timofeev. "Instant Location Detection of Objects Moving at High-Speedin C-OTDR Monitoring Systems." September 2, 2015. https://doi.org/10.5281/zenodo.1109127.
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The practical efficient approach is suggested to estimate the high-speed objects instant bounds in C-OTDR monitoring systems. In case of super-dynamic objects (trains, cars) is difficult to obtain the adequate estimate of the instantaneous object localization because of estimation lag. In other words, reliable estimation coordinates of monitored object requires taking some time for data observation collection by means of C-OTDR system, and only if the required sample volume will be collected the final decision could be issued. But it is contrary to requirements of many real applications. For example, in rail traffic management systems we need to get data of the dynamic objects localization in real time. The way to solve this problem is to use the set of statistical independent parameters of C-OTDR signals for obtaining the most reliable solution in real time. The parameters of this type we can call as «signaling parameters» (SP). There are several the SP’s which carry information about dynamic objects instant localization for each of COTDR channels. The problem is that some of these parameters are very sensitive to dynamics of seismoacoustic emission sources, but are non-stable. On the other hand, in case the SP is very stable it becomes insensitive as rule. This report contains describing of the method for SP’s co-processing which is designed to get the most effective dynamic objects localization estimates in the C-OTDR monitoring system framework.
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Andrey, V. Timofeev. "Monitoring the Railways by Means of C-OTDR Technology." April 4, 2015. https://doi.org/10.5281/zenodo.1100523.
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This paper presents development results of the method of seismoacoustic activity monitoring based on usage vibrosensitive properties of optical fibers. Analysis of Rayleigh backscattering radiation parameters changes, which take place due to microscopic seismoacoustic impacts on the optical fiber, allows to determine seismoacoustic emission sources positions and to identify their types. Results of using this approach are successful for complex monitoring of railways.
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Andrey, V. Timofeev. "Lipschitz Classifiers Ensembles: Usage for Classification of Target Events in C-OTDR Monitoring Systems." April 1, 2015. https://doi.org/10.5281/zenodo.1100474.
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This paper introduces an original method for guaranteed estimation of the accuracy for an ensemble of Lipschitz classifiers. The solution was obtained as a finite closed set of alternative hypotheses, which contains an object of classification with probability of not less than the specified value. Thus, the classification is represented by a set of hypothetical classes. In this case, the smaller the cardinality of the discrete set of hypothetical classes is, the higher is the classification accuracy. Experiments have shown that if cardinality of the classifiers ensemble is increased then the cardinality of this set of hypothetical classes is reduced. The problem of the guaranteed estimation of the accuracy for an ensemble of Lipschitz classifiers is relevant in multichannel classification of target events in C-OTDR monitoring systems. Results of suggested approach practical usage to accuracy control in C-OTDR monitoring systems are present.
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Garcia-Ruiz, Andres, Juan Pastor-Graells, Hugo F. Martins, Sonia Martin-Lopez та Miguel Gonzalez-Herraez. "Speckle Analysis Method for Distributed Detection of Temperature Gradients With $Φ $ OTDR". 15 вересня 2016. https://doi.org/10.1109/lpt.2016.2578043.
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A method to extend the operation of traditional single-frequency phase-sensitive optical time-domain reflectometry ( phi-OTDR) to the monitoring of distributed temperature gradients along an optical fiber is proposed and experimentally validated. The measurement principle is derived from the perturbation response of a single-wavelength phi-OTDR signal, which is analyzed as a unidimensional speckle pattern. The method could be implemented in parallel to standard phi-OTDR systems used for distributed vibration sensing with a close to zero cost and without affecting its operation, as it only requires a low computational cost post-processing of the traces which are already acquired. Frequency scanning of the laser, heterodyning or additional hardware are not required. The distributed detection of a temperature gradient of 2.5 °C over 10 min is demonstrated.
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Andrey, V. Timofeev, V. Egorov Dmitry, and M. Denisov Viktor. "The Rail Traffic Management with Usage of C-OTDR Monitoring Systems." July 2, 2015. https://doi.org/10.5281/zenodo.1107495.
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This paper presents development results of usage of C-OTDR monitoring systems for rail traffic management. The COTDR method is based on vibrosensitive properties of optical fibers. Analysis of Rayleigh backscattering radiation parameters changes which take place due to microscopic seismoacoustic impacts on the optical fiber allows to determine seismoacoustic emission source positions and to identify their types. This approach proved successful for rail traffic management (moving block system, weigh- in-motion system etc.).
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Andrey, V. Timofeev, and M. Denisov Viktor. "Robust Adaptation to Background Noise in Multichannel C-OTDR Monitoring Systems." July 5, 2015. https://doi.org/10.5281/zenodo.1108008.
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A robust sequential nonparametric method is proposed for adaptation to background noise parameters for real-time. The distribution of background noise was modelled like to Huber contamination mixture. The method is designed to operate as an adaptation-unit, which is included inside a detection subsystem of an integrated multichannel monitoring system. The proposed method guarantees the given size of a nonasymptotic confidence set for noise parameters. Properties of the suggested method are rigorously proved. The proposed algorithm has been successfully tested in real conditions of a functioning C-OTDR monitoring system, which was designed to monitor railways.
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Andrey, V. Timofeev. "Multi-Channel Information Fusion in C-OTDR Monitoring Systems: Various Approaches to Classify of Targeted Events." June 5, 2015. https://doi.org/10.5281/zenodo.1106893.
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The paper presents new results concerning selection of optimal information fusion formula for ensembles of C-OTDR channels. The goal of information fusion is to create an integral classificator designed for effective classification of seismoacoustic target events. The LPBoost (LP-β and LP-B variants), the Multiple Kernel Learning, and Weighing of Inversely as Lipschitz Constants (WILC) approaches were compared. The WILC is a brand new approach to optimal fusion of Lipschitz Classifiers Ensembles. Results of practical usage are presented.
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Wang, Zi, Yang-En Zou, Chen-Yin Guo та ін. "Integration of BOTDA and φ-OTDR Distributed Fiber Sensing for Multiple Parameters Monitoring". Physica Scripta, 26 лютого 2025. https://doi.org/10.1088/1402-4896/adbab9.
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Abstract In this article, the integration of the Brillouin optical time-domain analysis (BOTDA) and the phase-sensitive optical time domain reflectometry (φ-OTDR) distributed fiber sensing systems is discussed. By combining the two systems and sharing common instruments, the cost of the experiments is minimized, enabling the sensing of three parameters: temperature, strain, and vibration on the same 18.7 km fiber. In the BOTDA part, the focus is on temperature and strain analysis. Two 4m dispersion shifted fibers (DSF) are used to simulate strain at different positions, causing the Brillouin frequency shift (BFS) to shift from 10.88 GHz to 10.52 GHz, allowing for strain sensing. The two 4m single mode fibers and DSF are separately heated from room temperature to 200°C, resulting in an R2 value of 0.97654 and 0.99958, respectively, indicating a good linear relationship. In the φ-OTDR section, vibration point frequencies were demodulated using an external interferometer system based on Mach-Zehnder interferometer (MZI). This article presents comprehensive experiments that demonstrate the ability to achieve multi-parameter sensing on a single fiber using a hybrid system, all within a low-cost framework.
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Andrey, V. Timofeev, and V. Egorov Dmitry. "The Sequential Estimation of the Seismoacoustic Source Energy in C-OTDR Monitoring Systems." October 5, 2015. https://doi.org/10.5281/zenodo.1110129.
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The practical efficient approach is suggested for estimation of the seismoacoustic sources energy in C-OTDR monitoring systems. This approach is represents the sequential plan for confidence estimation both the seismoacoustic sources energy, as well the absorption coefficient of the soil. The sequential plan delivers the non-asymptotic guaranteed accuracy of obtained estimates in the form of non-asymptotic confidence regions with prescribed sizes. These confidence regions are valid for a finite sample size when the distributions of the observations are unknown. Thus, suggested estimates are non-asymptotic and nonparametric, and also these estimates guarantee the prescribed estimation accuracy in form of prior prescribed size of confidence regions, and prescribed confidence coefficient value.
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Andrey, V. Timofeev, and Egorov Dmitry. "Surveillance of Super-Extended Objects: Bimodal Approach." August 2, 2014. https://doi.org/10.5281/zenodo.1096023.
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This paper describes an effective solution to the task of a remote monitoring of super-extended objects (oil and gas pipeline, railways, national frontier). The suggested solution is based on the principle of simultaneously monitoring of seismoacoustic and optical/infrared physical fields. The principle of simultaneous monitoring of those fields is not new but in contrast to the known solutions the suggested approach allows to control super-extended objects with very limited operational costs. So-called C-OTDR (Coherent Optical Time Domain Reflectometer) systems are used to monitor the seismoacoustic field. Far-CCTV systems are used to monitor the optical/infrared field. A simultaneous data processing provided by both systems allows effectively detecting and classifying target activities, which appear in the monitored objects vicinity. The results of practical usage had shown high effectiveness of the suggested approach.
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Timofeev, A. V. "Comparison of various approaches to multi-channel Information fusion in c-otdr systems for remote monitoring of extended objects." Scientific and Technical Journal of Information Technologies, Mechanics and Optics, February 26, 2015, 122–29. http://dx.doi.org/10.17586/2226-1494-2015-15-1-122-129.
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