scholarly journals Autonomous Instrumentation for Measuring Electromagnetic Radiation from Rocks in Mine Conditions—A Functional Analysis

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 600
Author(s):  
Krzysztof Maniak ◽  
Remigiusz Mydlikowski

This paper analyses the function of an innovative integrated receiver for the measurement of electromagnetic field emissions. The autonomous receiver measures and registers the elevated emission levels of both components of the EM field originating from rocks subjected to increased mechanical stress. The receiver’s sensitivity of 60 µV/m, its dynamic range of 98 dB, and its impulse response of 0.23 V/µs were determined in laboratory conditions. Real EM field signals from hard coal samples subjected to crushing force were recorded using an autonomous receiver. The observed and recorded results confirm that the receiver operates in the full range of amplitudes of the EM field signal emitted from the rock. The results determine the band of characteristic signals for EM field emission from hard coal. The system created on the basis of autonomous EM receivers can support the existing seismic safety systems in real mine conditions by predicting the possibility of mine collapse hazards.

2019 ◽  
Vol 4 (2019) ◽  
pp. 30-35
Author(s):  
Remigiusz Mydlikowski ◽  
Krzysztof Maniak

The article presents the results of research concerning electromagnetic (EM) field emitted by rocks during the process of their destruction. The paper describes a measuring stand designed for subjecting rock samples to axial crushing. During the destruction of rock samples, both components of the electromagnetic field emitted by the rock were recorded. The paper presents the results of research on hard coal samples, presenting the obtained time domain waveforms and frequency spectrum of the emitted EM field components. Further potential uses of tests concerned with EM emitted by rocks are determined. Applications registering EM field in mine environments may provide an early mine collapse warnings.


Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1184 ◽  
Author(s):  
Mohammad Abdolrazzaghi ◽  
Mojgan Daneshmand

This paper presents a novel planar multifunctional sensor that is used to monitor physical variations in the environment regarding distance, angle, and stretch. A double split-ring resonator is designed at 5.2 GHz as the core operating sensor. Another identical resonator is placed on top of the first one. The stacked configuration is theoretically analyzed using an electric circuit model with a detailed parameter extraction discussion. This design is first employed as a displacement sensor, and a compelling high sensitivity of 500 MHz/mm is observed for a wide dynamic range of 0-5 mm. Then, in another configuration, the stacked design is used as a rotation sensor that results in a high sensitivity of 4.5 MHz/ ° for the full range of 0-180 ° . In addition, the stacked resonator is utilized as a strain detector, and a 0–30% stretch is emulated with a linear sensitivity of 12 MHz/%. Measurements are well in congruence with simulated results, which proves the accurate functionality of the sensor in tracking mechanical deformations, all in a single compact contraption.


Author(s):  
Emil Kichev ◽  
Ivan Ivanov ◽  
Kaliopa Mancheva ◽  
Yasen Petrov ◽  
Vesselina Vladimirova ◽  
...  

Refueling outages at the Kozloduy Nuclear Power Plant (KNPP) Units 5 and 6 are used to perform annual repairs and preventive maintenance activities, piping inspections, and test activities. A refueling outage at KNPP typically requires 60 days and occurs on an annual basis. Testing of safety systems at the KNPP Units 5 and 6 is an extensive exercise that results in multiple actuations of all components during each test and a relatively high number of component actuations each year. This results in equipment wear out issues that can lead to considerable component replacement and/or refurbishment. Numerous piping in-service inspections are conducted in locations where there has been no industry or plant-specific indications or failures, leading to unnecessary personnel exposure. KNPP is interested in using risk-informed (RI) approaches to reduce refueling outage length, piping inspections, testing, and exposure. KNPP is a four-loop Voda-Vodyanoi Energetichesky Reaktor (VVER) with a power level of 1000 MWe. Safety systems consist of three trains. The KNPP at-power probabilistic safety assessment (PSA) model includes internal and external events. It addresses the full range of events leading to core damage frequency (CDF) and includes a simplified level 2 model leading to large early release frequency (LERF). The RI approach, as defined in the U.S. Nuclear Regulatory Commission’s (NRC’s) risk-informed (RI) Regulatory Guides (RGs) 1.174, 1.177, and 1.178, was used in this program. The specific approach used for risk-informed in-service inspection (RI-ISI) is based on the Pressurized Water Reactor Owner’s Group methodology. The overall approach for each of the three applications used a multi-step process which included the following: identification of systems to address; identification of alternatives to current maintenance, inspection, and testing practices; a risk assessment of the proposed alternatives; an assessment of the impact of the changes on deterministic considerations; identification of monitoring requirements; and an assessment of the economic benefits. The RI-ISI program also considered the impact of the changes on personnel exposure. The overall approach made extensive use of data assessments, reliability methods, and risk assessments. The results demonstrated that the proposed changes in maintenance, in-service inspection, and testing programs have a small impact on risk, based on CDF and LERF. In addition, the proposed changes provide significant benefits in terms of reduced outage time, in-service inspections, testing requirements, and personnel exposure. The economic analysis demonstrated that changes to the maintenance program provide the largest benefit followed by the changes to the in-service inspection program and then the changes to the testing program.


Geophysics ◽  
1998 ◽  
Vol 63 (2) ◽  
pp. 750-762 ◽  
Author(s):  
Klaus Helbig

The amplitudes of seismic waves have always been a foremost concern of the seismologist to which considerable ingenuity was devoted. In the 1920s the problem was to magnify the ground motion sufficiently for detection. This was done at first by simple levers that moved mechanical pens. But at the start of exploration seismology, this had already been superseded by optical levers, photographic recording, and (soon after) electromechanical transduction followed by amplification. From the 1930s to about the early ’60s, devices of increasing complexity were introduced to compress the large amplitude difference between the first arrivals and the weakest reflections of interest to the limited dynamic range of the recording medium: first the paper record, then magnetic storage media, and finally the digital magnetic tape. This period can be identified with techniques known as automatic gain control (AGC). Soon after the introduction of digital recording techniques, the emphasis shifted: with intermediate digital storage, the limit to the dynamic range was no longer controlled by the properties of the storage medium. Now everything that passed through the acquisition unit could, in principle, be stored on magnetic disk or tape. At that time the aim became to record the ground motion as faithfully as possible. There were several technical developments on the way to achieve “true amplitudes” that, in turn, made exploration concepts like bright spots, seismic stratigraphy, and amplitude‐versus‐offset evaluation possible. However, the most significant innovation was what became known as floating‐point amplifier. It dominated seismic acquisition for about 25 years. Floating‐point representation of seismic signals allowed storage of the entire dynamic range in relatively economic words of about 18 bits. During the last decade, the quest for ever‐greater resolution—and the availability of mass‐produced components for hi‐fi audio equipment—led to the introduction of the sigma‐delta (Σ-δ) converter. With this device, the full range of the seismic signal (or rather the geophone output) is recorded in binary fixed‐point formats with 24 bits. With this development, the full seismic signal can be stored without distortion or loss of resolution.


Author(s):  
João P. A. Martins ◽  
Isabel F. Trigo ◽  
Virgílio A. Bento ◽  
Carlos da Camara

Land Surface Temperature (LST) is routinely retrieved from remote sensing instruments using semi-empirical relationships between top of atmosphere (TOA) radiances and LST, using ancillary data such as total column water vapor or emissivity. These algorithms are calibrated using a set of forward radiative transfer simulations that return the TOA radiances given the LST and the thermodynamic profiles. The simulations are done in order to cover a wide range of surface and atmospheric conditions and viewing geometries. This work analyses calibration strategies, considering some of the most critical factors that need to be taken into account when building a calibration dataset, covering the full dynamic range of relevant variables. A sensitivity analysis of split-windows and single channel algorithms revealed that selecting a set of atmospheric profiles that spans the full range of surface temperatures and total column water vapor combinations that are physically possible seems beneficial for the quality of the regression model. However, the calibration is extremely sensitive to the low-level structure of the atmosphere indicating that the presence of atmospheric boundary layer features such as temperature inversions or strong vertical gradients of thermodynamic properties may affect LST retrievals in a non-trivial way. This article describes the criteria established in the EUMETSAT Land Surface Analysis – Satellite Application Facility to calibrate its LST algorithms applied both for current and forthcoming sensors.


Author(s):  
Д.Г. Таймазов ◽  
С.А. Мамаев ◽  
А.С. Мамаев

Обсуждаются перспективы использования новых аппаратурно-методических разработок Института геологии ДФИЦ РАН для повышения сейсмической безопасности территории Дагестана. По предварительным расчетам разработанная на их базе деформационная станция траншейного типа (ДСТТ) в десятки раз дешевле и эффективнее, чем известная подземная деформационная станция штольневого типа, что делает реальным создание в сейсмоопасных районах сети ДСТТ и существенно расширит круг контролируемых параметров земной коры. В число этих параметров войдут локальные объемные деформации вмещающей среды, локальные линейные деформации в трех ортогональных координатах, величина и направление максимальных сдвиговых деформаций, азимут простирания и угол падения плоскости максимальных сдвиговых деформаций, деформация кручения относительно вертикальной оси, сейсмодеформации по трем координатам в широком частотном и динамическом диапазоне, локальные наклоны по двум ортогональным азимутам, сейсмоакселерограммы по трем ортогональным координатам в динамическом диапазоне 100 децибел, среднемасштабные (100 м) линейные деформации по трем ортогональным координатам, градиенты среднемасштабных линейных деформаций, среднемасштабные наклоны земной коры в двух ортогональных азимутах, крупномасштабные горизонтальные движения земной коры, вертикальные движения земной коры неприливные изменения силы тяжести и ее производных, обусловленные тектоническими причинами, амплитуды и фазы приливных гармоник во временных изменениях деформаций, наклонов, силы тяжести и ее градиентов. Становится возможным регулярное разномасштабное картирование всех перечисленных параметров, что означает качественно новый уровень деформационного мониторинга земной коры. Показана целесообразность использования комплекса для организации сейсмопрогностических наблюдений на территории Дагестана. К другим областям возможного применения разработок относятся геологоразведка, прецизионные гравитационные эксперименты, деформационный мониторинг крупных инженерных сооружений, прецизионные станки и системы позиционирования, что придает их реализации дополнительную актуальность. Описанный комплексный мониторинг предложено дополнить режимным просвечиванием сейсмоактивных зон Восточного Кавказа с использованием тяжелых вибросейсмоисточников и сейсмическим микрорайонированием крупных населенных пунктов в соответствие с существующими нормами и правилами. The prospects of using new hardware and methodological developments of the Institute of Geology of the Dagestan Federal Research Center of RAS to improve the seismic safety of the territory of Dagestan are discussed. According to the preliminary calculations, the trench-type deformation station (TTDS) developed on their basis is ten times cheaper and more efficient than the well-known underground deformation tunnel-type station, which makes it possible to create a TTDS network in seismically hazardous areas and which expand significantly the range of controlled parameters of the earths crust. These parameters will include local volumetric deformations of the host medium, local linear deformations in three orthogonal coordinates, the magnitude and direction of maximum shear deformations, the strike azimuth and the angle of incidence of the plane of maximum shear deformations, torsional deformation relative to the vertical axis, seismic deformation along three coordinates in a wide frequency and dynamic range, local slopes along two orthogonal azimuths, seismic accelerograms along three orthogonal coordinates in dynamic range 100 decibels medium-scale (100 m) linear deformations along three orthogonal coordinates, gradients of medium-scale linear deformations, medium-scale crustal tilts in two orthogonal azimuths, large-scale horizontal earths crust movement, vertical movement of the earths crust non-tidal changes in gravity and its derivatives caused by the tectonic reasons, the amplitudes and phases of tidal harmonics in temporal variations of deformations, inclinations, gravity and its gradients. It becomes possible a regular multi-scale mapping of all these parameters, which means a qualitatively new level of deformation monitoring of the earths crust. The expediency of using the complex for the organization of seismic-prediction observations in the territory of Dagestan is shown. Other areas of potential development applications include geological exploration, precision gravity experiments, strain monitoring of large engineering structures, precision machines and positioning systems, which gives their implementation additional relevance. It is proposed to supplement the described complex monitoring with regime transmission of seismically active zones of the East Caucasus using heavy vibro-seismic sources and seismic microzonation of large settlements following the existing norms and rules


Author(s):  
J. M. Van Niekerk ◽  
B. M. J. W. van der Veer ◽  
C. J. P. A. Hoebe ◽  
J van de Bovenkamp ◽  
C van Herk ◽  
...  

Objectives : Oropharyngeal Chlamydia trachomatis (CT) and especially Neisseria gonorrhoeae (NG) infections are common but few commercial nucleic acid amplification tests (NAATs) specify extragenital samples as intended use. The test characteristics of the cobas®4800 CT/NG assay are evaluated for oropharyngeal swabs. Methods: The technical validation includes analysis of the specificity, sensitivity, dynamic range, linearity, efficiency and precision. The probability of detection curve combined with historical data enables estimation of potentially missed diagnoses. A clinical evaluation has been performed on a subset of 2798 clinical samples available from routine diagnostics. Results of the cobas®4800 were compared with in-house CT/NG PCR assays. Discrepant samples were tested with resolver assays and these results were considered decisive. Results: No cross-reactivity was seen in the analytical specificity analysis. High linearity (≥0.983 R2), efficiency (89%-99%), and precision (0.1-0.9 Ct-value) were seen for both CT/NG. The limit of detection in oropharyngeal samples was 3.2x102 IFU/mL for CT and 6.7x102 CFU/mL for NG. Estimates on potentially missed diagnoses were up to 7.2% for CT and up to 24.7% for NG. Clinical sensitivity and specificity were evaluated with 25 CT, 86 NG positive and 264 negative samples, resulting in 100% and 99.6% for CT and 100% and 96.7% for NG respectively. Conclusion: The findings in this study demonstrate the utility of the cobas®4800 CT/NG assay for oropharyngeal samples. Despite being a highly accurate test, the range of reported Ct-values especially for NG suggest relatively low oropharyngeal loads. Hence, consistent detection over the full range of oropharyngeal loads could be impaired.


2005 ◽  
Vol 22 (4) ◽  
pp. 417-436 ◽  
Author(s):  
R.D. HAMER ◽  
S.C. NICHOLAS ◽  
D. TRANCHINA ◽  
T.D. LAMB ◽  
J.L.P. JARVINEN

Recently, we introduced a phototransduction model that was able to account for the reproducibility of vertebrate rod single-photon responses (SPRs) (Hamer et al., 2003). The model was able to reproduce SPR statistics by means of stochastic activation and inactivation of rhodopsin (R*), transducin (Gα), and phosphodiesterase (PDE). The features needed to capture the SPR statistics were (1) multiple steps of R* inactivation by means of multiple phosphorylations (followed by arrestin capping) and (2) phosphorylation dependence of the affinity between R* and the three molecules competing to bind with R* (Gα, arrestin, and rhodopsin kinase). The model was also able to account for several other rod response features in the dim-flash regime, including SPRs obtained from rods in which various elements of the cascade have been genetically disabled or disrupted. However, the model was not tested under high light-level conditions. We sought to evaluate the extent to which the multiple phosphorylation model could simultaneously account for single-photon response behavior, as well as responses to high light levels causing complete response saturation and/or significant light adaptation (LA). To date no single model, with one set of parameters, has been able to do this. Dim-flash responses and statistics were simulated using a hybrid stochastic/deterministic model and Monte-Carlo methods as in Hamer et al. (2003). A dark-adapted flash series, and stimulus paradigms from the literature eliciting various degrees of light adaptation (LA), were simulated using a full differential equation version of the model that included the addition of Ca2+-feedback onto rhodopsin kinaseviarecoverin. With this model, using a single set of parameters, we attempted to account for (1) SPR waveforms and statistics (as in Hamer et al., 2003); (2) a full dark-adapted flash-response series, from dim flash to saturating, bright flash levels, from a toad rod; (3) steady-state LA responses, including LA circulating current (as in Koutalos et al., 1995) and LA flash sensitivity measured in rods from four species; (4) step responses from newt rods (Forti et al., 1989) over a large dynamic range; (5) dynamic LA responses, such as the step-flash paradigm of Fain et al. (1989), and the two-flash paradigm of Murnick and Lamb (1996); and (6) the salient response features from four knockout rod preparations. The model was able to meet this stringent test, accounting for almost all the salient qualitative, and many quantitative features, of the responses across this broad array of stimulus conditions, including SPR reproducibility. The model promises to be useful in testing hypotheses regarding both normal and abnormal photoreceptor function, and is a good starting point for development of a full-range model of cone phototransduction. Informative limitations of the model are also discussed.


2021 ◽  
Author(s):  
Iwona Kudłacik ◽  
Jan Kapłon

<p>High-rate GNSS (HR-GNSS) observations are used for high-precision applications, where the point position changes in short intervals are required, such as earthquake analysis or structural health monitoring. We aim to apply the HR-GNSS observations into mining tremors monitoring, where the dynamic displacement amplitudes reach maximally dozens of millimetres. The study contains the analysis of several mining tremors of magnitudes 3-4 in Poland, recorded within the EPOS-PL project.</p><p>The HR-GNSS position is obtained with over 1 Hz frequency in kinematic mode with relative or absolute approaches. For short periods (up to several minutes), the positioning accuracy is very high, but the displacement time series suffer from low-frequency fluctuations. Therefore, it is not possible to apply them directly in the analysis of seismic phenomena, thus it is necessary to filter out low- and high-frequency noise.</p><p>In this study, we discussed some methods that are useful to reduce the noise in HR-GNSS displacement time series to obtain precise and physically correct results with reference to seismological observations, which for dynamic position changes are an order of magnitude more accurate. We presented the band-pass filtering application with automatic filtration limits based on occupied bandwidth detection and the discrete wavelet transform application with multiresolution analysis. The correction of noise increases the correlation coefficient by over 40%, reaching values over 0.8. Moreover, we tested the application of the basic Kalman filter to the integration of sensors: HR-GNSS and an accelerometer to visualize the most actual displacements of the station during a small earthquake - a mining tremor. The usefulness of this algorithm for the assumed purpose was confirmed. This algorithm allows to reduce the noise from HR-GNSS results, and on the other hand, to minimize the potential seismograph drift and its errors caused by the limited dynamic range of the seismograph. An unquestionable advantage is the possibility of obtaining a time series of displacements with a high frequency (equal to the frequency of seismograph observations, e.g. 250 Hz) showing the full range of station motion: dynamic and static displacements caused by an earthquake.</p>


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