SUMMARY
In this paper, we propose a two-step procedure for the automated detection of micro-earthquakes, using single-station, three-component passive seismic data. The first step consists of the ...computation of an appropriate characteristic function, along with an energy-based thresholding scheme, in order to attain an initial discrimination of the seismic noise from the ‘useful’ information. The three-component data matrix is factorized via the singular value decomposition by means of a properly selected moving window and for each step of the windowing procedure a diagonal matrix containing the estimated singular values is formed. The ${L_2}$-norm of the singular values resulting from the above-mentioned windowing process defines the time series which serves as a characteristic function. The extraction of the seismic signals from the initial record is achieved by following a histogram-based thresholding scheme. The histogram of the characteristic function, which constitutes its empirical probability density function, is estimated and the optimum threshold value is chosen corresponds to the bin that separates the above-mentioned histogram in two different areas delineating the background noise and the outliers. Since detection algorithms often suffer from false alarms, which increase in extremely noisy environments, as a second stage, we propose a new ‘decision-making’ scenario to be applied on the extracted intervals, for the purpose of decreasing the probability of false alarms. In this context, we propose a methodology, based on comparing among autoregressive models estimated both on isolated seismic noise, in addition to the detections resulting from the first stage. The performance and efficiency of the proposed technique is supported by its application to a series of experiments that were based on both synthetic and real data sets. In particular, we investigate the effectiveness of the characteristic function, along with the thresholding scheme by subjecting them to noise robustness tests using synthetic seismic noise, with different statistical characteristics and at noise levels varying from 5 down to –5 dB. Results are compared with those obtained by the implementation of a three-component version of the well-known STA/LTA algorithm to the same data set. Moreover, the proposed technique and its potential to distinguish seismic noise from the useful information through the proposed decision making scheme is evaluated, by its application to real data sets, acquired by three-component short-period recorders that were installed for monitoring the microseismic activity in areas characterized by different noise attributes.
This study performs a reanalysis of the seismicity recorded during the 1996 Gjálp eruption that occurred at NW Vatnajökull, Iceland. The seismicity was recorded by the temporary HOTSPOT network ...consisting of 30 three-component broadband stations. In total 301 events were identified between 29 September and 12 October and their phases were manually picked. A velocity model was estimated from P-phase travel times by using VELEST. Events were first located using the algorithm NONLINLOC in order to obtain absolute locations. Precise relative locations were obtained with HYPODD by utilizing catalog and cross-correlation differential travel times. Results show that events clustered first along the SW rim of the Bárðarbunga caldera and later along the Gjálp fissure, with most hypocentral depths located between 3 and 8 km. Waveforms of the 10 largest events that followed the Bárðarbunga earthquake were inverted in order to obtain moment tensors. For all events we found that the deviatoric moment tensor fits the data better than pure double-couple or full moment tensor solutions. Events along the Bárðarbunga caldera exhibited reverse focal mechanisms, while those at the Gjálp fissure exhibited mostly strike-slip faulting. Seismic velocity variations calculated using ambient noise interferometry, point to the possibility that a small subglacial eruption occurred at Bárðarbunga before the main earthquake. This removed melt from the magma chamber causing its roof to collapse, and also resulted in the lateral migration of magma towards the Gjálp fissure. The 2014–2015 Bárðarbunga–Holuhraun eruption shares common characteristics with the 1996 Gjálp eruption, although the size of the latter was much smaller.
Polyvinylpyrrolidone (PVP), as a nitrogen-containing heterocyclic polymer, is a promising candidate for preparation of high performance iodide-based polymer electrolytes for dye-sensitized solar ...cells (DSSCs). In the present investigation, PVP electrolytes composed of different wt% loadings of potassium iodide and iodine were prepared, thoroughly characterized, and applied to DSSCs. The TiO2 electrode of the solid state DSSCs was optimized (film thickness, dye loading, TiCl4 treatment), to achieve high energy conversion efficiency. Differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy, linear sweep voltammetry, and ultraviolet–visible spectroscopy were used to characterize the PVP electrolytes. One-diode model equivalent circuit analysis was applied to DSSCs characteristic curve, in order to calculate the key electrical circuit elements values, determining solar cells efficiency. The maximum energy conversion efficiency attained by the solid state DSSCs under real test conditions was 3.74%, at about 1000 W/m2 irradiation intensity. By in-situ gelation of the PVP electrolytes onto TiO2, an optimal electrode film thickness on the order of 15 μm was achieved, which is very close to the corresponding value usually attained to liquid state DSSCs. The results are satisfactory compared to DSSCs employing liquid state factory available electrolytes, while simultaneously the PVP electrolytes preparation is simple and of low-cost, having great prospects for further optimization.
AR AND CHAMBER MUSIC: MUSICAL KALEIDOSCOPE Patias, P.; Georgoula, O.; Kaimaris, D. ...
International archives of the photogrammetry, remote sensing and spatial information sciences.,
01/2023, Letnik:
XLVIII-M-2-2023
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
DIGI-ORCH is a research project with objectives, on one hand, to design and develop "smart" brochures for concerts and educational programs of the State Conservatory of Thessaloniki (Greece), and, on ...the other, to develop an innovative system for the visualization of information on smart mobile devices (smartphones and tablets). The application of Augmented Reality (AR) provides free access to the information and content of the above concerts and educational programs, combining the information of a robust data server and an easy-to-use user interface of the smart device in real-time.The pilot implementation of the system in real conditions took place at the beginning of December 2022, in an event held at the facilities of the State Conservatory of Thessaloniki. The event was an evening of Chamber Music entitled Musical Kaleidoscope, with the internationally acclaimed artists Simos Papanas (violin), Dimos Goundaroulis (violoncello), and Vassilis Varvaresos (piano). They performed the Piano Trio no. 3 in G minor, Robert Schumann's opus 110, and the Piano Trio no. 2 in E flat major, Op. 100 D. 929 by Franz Schubert. The concert was attended by over 150 attendees.The paper will present the chaîne-operatoire of the development of the system, from the acquisition of raw data (text, video, image, and sound) to the methodology used to produce the "smart" event brochure and the AR application for the above concert. Essentially, this large amount of information that cannot be assessed by a regular printed concert brochure is included in the smart system and displayed on the mobile device when the user locates the appropriate AR patterns on the surface of the analog concert poster and/or on the pages of the brochure.This information comprised of ie. additional text and images about the composers and their musical projects, about the musicians of the concert (e.g. biographies), their interviews and rehearsals (video) before the concert, information about the State Conservatory of Thessaloniki (text, video, image, and sound), 3D models of musical instruments, 360° of the concert space, etc. diverse multimedia material.
On 2010 January 18 and 22, two earthquakes of MW 5.3 and 5.2, respectively, occurred near the town of Efpalio on the western Gulf of Corinth. We performed a shear wave splitting analysis using the ...cross-correlation method and calculated VP/VS ratios for events that occurred in the epicentral area of the Efpalio earthquakes, between 2009 January and 2010 December. The data analysis revealed the presence of shear wave splitting in the study area, as well as variations of the splitting parameters and VP/VS ratios. The average values of time-delay, fast polarization direction and VP/VS ratio for the time period before the Efpalio earthquakes, were calculated at 2.9 + or - 0.4 ms km (super -1) , 92 degrees + or - 10 degrees and 1.76 + or - 0.04, respectively, while after the occurrence of the earthquakes, including the aftershock sequence, they were calculated at 5.5 + or - 0.5 ms km (super -1) , 82 degrees + or - 9 degrees and 1.88 + or - 0.04. A few months after the occurrence of the Efpalio earthquakes, the mentioned splitting parameters were calculated at 3.6 + or - 0.4 ms km (super -1) and 83 degrees + or - 9 degrees . VP/VS ratio exhibited a mean value of 1.87 + or - 0.04. The mean fast polarization directions were in general consistent with the regional stress field, almost perpendicular to the direction of the extension of the Gulf of Corinth. The observed increase in the time-delays and VP/VS ratios after the Efpalio earthquakes indicates changes in the crustal properties, which possibly resulted from variations in the pre-existing microcrack system characteristics. We suggest that a migration of fluids in the form of overpressured liquids, which are likely originated from dehydration reactions within the crust, was triggered by the Efpalio earthquakes and caused the observed variations. The findings of this work are consistent with those of previous studies that have indicated the presence of fluids of crustal origin in the study area.
Technologies are difficult to assess in an early stage of development. A comparison between innovative and conventional technologies is often complex due to differences in scale (large-scale with ...several 100 t/d vs. demonstrator-scale with less than 100kg/d) and subsequent efficiency. A methodology is implemented using Key Performance Indicators (KPIs) enhanced by Life Cycle Assessment (LCA) aspects and incorporating industrial principles for technology assessment. The methodology is applied to identify the trade-off between direct and indirect emissions and to evaluate scale dependency with focus on energy and broader sustainability. The applicability is illustrated for glass and ceramic frits production and supported by experimental data for conventionally and innovatively heated processes.
Aims To assess insulin sensitivity and secretion in the fasting state in regularly transfused patients with β‐thalassaemia major with normal glucose response during an oral glucose tolerance test ...and to estimate its possible relation to iron overload.
Methods We measured fasting glucose, insulin and C‐peptide levels in 24 patients with β‐thalassaemia major and 18 control subjects matched for age and body mass index. Insulin sensitivity and insulin release index were calculated according to the homeostasis model assessment (HOMA). Correlations with age, body mass index and serum ferritin were also calculated.
Results Fasting glucose levels in patients were increased compared with control subjects (5.5 ± 0.12 vs. 4.7 ± 0.13 mmol/l, mean ± sem, P < 0.001). Pancreatic B‐cell insulin secretion in the fasting state (estimated by SCHOMA) was lower in thalassaemic patients (SCHOMA 88.5 ± 11.11 vs. 184.3 ± 23.72 in control subjects, P < 0.001). Patients were then divided into those with impaired (IFG) and normal (NFG) fasting glucose. SCHOMA was higher in the patients with NFG compared with those with IFG patients (110.6 ± 17.63 vs. 66.3 ± 10.88, respectively, P < 0.05) but estimated insulin sensitivity (ISIHOMA) was similar. Plasma values of C‐peptide correlated positively with ferritin (r = 0.42, P = 0.04) and SCHOMA (r = 0.45, P = 0.02) and negatively with ISIHOMA (r = −0.43, P = 0.03).
Conclusions These results support the concept that impaired B‐cell function, as reflected by a reduction in the insulin secretion index, is present in β‐thalassaemic patients with normoglycaemia before changes in oral glucose tolerance tests are apparent.
The paper provides an overall assessment of the environmental effects of co-incineration of cutting oil emulsions in cement plants through the quantification of emissions of key pollutants, namely ...NOx, CO and VOC. Two realistic scenarios are considered. In the first, the cutting oil emulsion is injected directly into the rotary kiln while the second scenario involves injection of the cutting oil emulsion in the tertiary air stream and thus directly into the precalciner. A detailed kinetic PSR modelling study is performed for combustion conditions relevant both to cement kiln and precalciner operating conditions. It is demonstrated that, although NOx emissions from the precalciner are generally substantially lower than those from the cement kiln, emulsion injection in the latter appears to be favourable and can lead up to 50% reductions in NO levels. However, injection of cutting oil emulsion with relatively high nitrogen content in the precalciner may lead, under lean conditions, to increases in the emitted NO levels. The effect of cutting oil emulsion on CO and VOC emissions both under cement kiln and precalciner conditions is also quantified.
The paper provides an overall assessment of the environmental effects of co-incineration of cutting oil emulsions in cement plants through the quantification of emissions of trace species, namely ...polychlorinated dioxins and furans and heavy metals. A detailed kinetic model for dioxin formation and destruction is developed and it is shown that under typical precalciner conditions PCDD/F emissions are well below regulatory limits. A two-phase CFD simulation of the flow and temperature field inside the tertiary air duct assesses the possibility of PCDD/F formation. It is demonstrated that fine atomization and sufficiently long tertiary air ducts virtually diminish the possibility of homogeneous PCDD/F formation. Furthermore, it is shown that emulsifiable cutting oils do not seem to carry a prohibitive metal loading, both in terms of quantity and quality (metal species carried), although case-specific composition analysis is a necessity.
Nearly a quarter of the energy consumption of Europe is required for industrial processes. Huge efficiency potentials can be exploited. One such is under research within the EU funded project DAPhNE ...by developing an integrated solution for energy intensive firing processes with microwave technologies. A methodology towards the preliminary definition of Key Performance Indicators (KPIs) with focus on economical, environmental and operational aspects is presented within this paper. By means of lab-scale measurements, the preliminary selected KPIs are determined and benchmarked against conventional KPIs to develop an eco-efficient production system. Moreover life cycle assessment (LCA) results support the evaluation and quantify the environmental benefits of microwave heating. Lab-scale results indicate a high carbon emission reduction potential.
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