bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular engineering of simple carbazole-arylamine hole-transport materials for perovskite solar cells
Authors: Liu Xuepeng , Ma Shuang , Mateen Muhammad , Shi Pengju , Liu Cheng , Ding Yong , Cai Molang , Guli Mina , Nazeeruddin Mohammad Khaja , Dai Songyuan
Published: January 2020

N,N-Dimethylamino-based carbazole-arylamine hole-transport materials show better performance than methylsulfanyl or methoxy counterparts in perovskite solar cells, and even exhibit higher efficiency and extremely lower laboratory synthesis cost than conventional spiro-OMeTAD.
Using nanoconfinement to inhibit the degradation pathways of conversion-metal oxide anodes for highly stable fast-charging Li-ion batteries
Authors: Ng Benjamin , Peng Xiong , Faegh Ehsan , Mustain William E.
Published: January 2020

Nanostructured hybrids that physically encapsulate highly morphable, high capacity Li-ion battery anodes can potentially enable much longer cycle life than straightforward deployment of the same chemistry.
An efficiently enhanced UV-visible light photodetector with a Zn:NiO/p-Si isotype heterojunction
Authors: Zhang Yongfang , Ji Tao , Zou Rujia , Ha Enna , Hu Xin , Cui Zhe , Xu Chaoting , He Shu’ang , Xu Kaibing , Zhang Yihong , Hu Junqing
Published: January 2020

A high-performance broadband photodetector based on a Zn:NiO/p-Si isotype heterojunction formed using a sol–gel process demonstrates an EQE as high as ∼184% at a reverse bias of −4 V.
Electrode-controlled confinement of conductive filaments in a nanocolumn embedded symmetric–asymmetric RRAM structure
Authors: Xiao Wen , Song Wendong , Feng Yuan Ping , Gao Daqiang , Zhu Yao , Ding Jun
Published: January 2020

A novel hybrid RRAM structure is developed combining symmetric and asymmetric structures to confine conductive filaments using cost-effective electrode materials.
A progressive learning method for predicting the band gap of ABO3 perovskites using an instrumental variable
Authors: Li Changjiao , Hao Hua , Xu Ben , Zhao Guanghui , Chen Lihao , Zhang Shujun , Liu Hanxing
Published: January 2020

A progressive learning method with an instrumental variable and bond-valence vector sums was used to improve the bandgap prediction precision.
Design optimisation of an axial‐flux reluctance magnetic coupling based on a two‐dimensional semi‐analytical model
Authors: Lubin Thierry , Vahaj Amir Abbas , Rahideh Akbar
Published: January 2020

In this study, design optimisation of an axial‐flux reluctance magnetic coupling is presented. The optimal design procedure is based on a two‐dimensional (2D) semi‐analytical model defined at the mean radius combined with a multi‐objective genetic algorithm (NSGA‐II). In order to take into account the end‐effects in the radial direction, a correction factor is defined to improve the torque and the axial‐force determination. The obtained results are compared with those of 3D non‐linear finite element simulations and experimental results. It is shown that the proposed semi‐analytical model is very accurate and requires very little computing time.
Network partitioning approach for reactive power/voltage control using analytical nodes coupling expressions
Authors: Li Weixing , Tian Aina , Ma Jin , Mou Xiaoming , Liang Xiaodong
Published: January 2020

Power‐grid partitioning is an important prerequisite for power systems security analysis and control. In this study, a novel recursive grid bipartitioning strategy is proposed. First, two analytical expressions are derived from Kirchhoff's equations to represent coupling relationships between nodes. Then, generator nodes under study are divided into two groups by recursively applying the coupling relationships between generator nodes. Finally, the coupling relationships between generator and load nodes are used to merge relevant load nodes to the corresponding groups of generators. The stopping criterion of the grid bipartitioning process is also discussed. The proposed bipartitioning strategy is implemented on the IEEE 118‐bus system and a practical provincial power grid in China to demonstrate its effectiveness.
Algorithm for phasor estimation during current transformer saturation and/or DC component presence: definition and application in arc detection on overhead lines
Authors: Belčević Nenad M. , Stojanović Zoran N.
Published: January 2020

During the current transformer (CT) saturation, the secondary current waveform of a CT is notably different from the primary current's waveform. When the discrete Fourier transform (DFT) is applied to such a distorted secondary current of a CT, the obtained root mean square (RMS) value is significantly lower than it actually is, which can lead to the malfunctioning of the relay protection devices. The operation of some relay protection algorithms (such as certain algorithms for electric arc detection on overhead lines) is conditioned by higher fault current harmonics. Obviously, due to the secondary current's distortion, the higher current harmonics cannot be accurately estimated. On the other hand, even when there is no CT saturation, the RMS value can be incorrectly estimated under DFT due to the fault current's direct component. This study presents a new algorithm which enables an accurate RMS value estimation regardless of the CT saturation and/or presence of the direct fault current component. What is more, the algorithm also enables the estimation of higher fault current harmonics under CT saturation. Various tests have indicated a high precision and robustness of the proposed algorithm and the possibility of combining this algorithm with the algorithm for electric arc detection on overhead lines.
On‐line monitoring device for dry zone formation in the soil surrounding underground power cables
Authors: Gouda Osama E. , Osman Gomaa F.A.
Published: January 2020

Formation of dry zones around power cables is an important factor affecting the cable loading and may lead to cable failure. This phenomenon is ignored by some standards in the calculation of power cables capacity. Numerous efforts have been done by many researchers for cable monitoring. In this study, monitoring system based on measurements of temperature distribution surrounding the cable route is suggested. When reaching the temperature of the dry zone formation the system will produce a warning alarm. To the best of the authors knowledge, the invention of a device that gives a warning in the case of drying layers formation around the power cables has not received attention so far. The proposed device is characterised by cheap price, high accuracy and its simplicity in the design. The system is tested in the laboratory using different soil types. Field tests are done to verify the reliability of the device.
Operation and control of hybrid HVDC system with LCC and full‐bridge MMC connected in parallel
Authors: Xiao Huangqing , Sun Kaiqi , Pan Jiuping , Liu Yilu
Published: January 2020

In this study, a new kind of hybrid high‐voltage direct current (HVDC) system is proposed. Each terminal of the proposed system consists of one line commutated converter (LCC) and one full‐bridge modular multilevel converter (FB‐MMC). The LCC and FB‐MMC are connected in parallel so that they can share the same transmission line. The active–reactive power capability of the hybrid HVDC system is extended compared with the conventional LCC‐HVDC system, and power reversal control without power interruption can be achieved by the coordination control of LCC and FB‐MMC. Besides, the proposed hybrid HVDC system is capable of handling DC fault, because both LCC and FB‐MMC have DC fault blocking capability. Moreover, the power rating of FB‐MMC can be designed to low value while keeping the bulk‐power transmission capability of LCC. A two‐terminal bipolar hybrid HVDC system is built in PSCAD/EMTDC. The simulation results verify the effectiveness and feasibility of the proposed hybrid topology and corresponding control strategies.
Improved tight and effective two‐binary‐variable formulations for UC problems
Authors: Yang Linfeng , Fang Beihua , Zhang Chen , Li Wei
Published: January 2020

This study presents two mixed‐integer programmings formulations for the unit commitment (UC) problem. First, the authors proposed a variable upper bound‐based UC formulation, which is simultaneously tight and compact. Moreover, the tighter and relatively compact multi‐period formulation is also presented. Both formulations (‘Multi_New’ and ‘Mult’) are tighter than the previous 2‐bin (Base) and the tighter characteristic largely reduces the computational time of the formulations. Compared to the ‘Base’ formulation, the proposed formulations reduced by at least 6.6%, even 42.1% in the average time of calculation. The proposed models were tested on 73 instances over a scheduling period of 24 and 48 h. Compared to the ‘Base’ formulation, the initial Gap of ‘New’ formulation is improved by at least 8.4%. Moreover, compared to ‘Multi’ formulation, the compactness of ‘Multi_New’ formulation is improved by at least 33%. In addition, the numeric experiments show dramatic improvements in computational time for their proposed models. They provide evidence that the proposed models have better performance than the previous models.
Efficient electronic beam steering method in time modulated linear arrays
Authors: Gassab Oussama , Azrar Arab , Dahimene Abdelhakim , Bouguerra Sara , He Chong
Published: January 2020

An efficient electronic beam steering technique in time modulated linear array (TMLA) is proposed, where the first positive and negative sidebands are utilised to implement the electronic steering process. In this technique, new periodic time sequences are used, in which a positive‐ON, negative‐ON, and OFF durations are utilised to obtain high sufficient steering in TMLA. Furthermore, it is shown that by using these time sequences, the non‐steerable array pattern at the fundamental frequency and also the even sidebands can be eliminated and nulled to zero. In addition, the radiation power and the directivity of this proposed steered‐TMLA are formulated in their closed form. The genetic algorithm is implemented to optimise the steered‐TMLA by suppressing the remaining odd sidebands and increasing the power radiation at the first positive and negative sidebands.
MCMCI: A code to fully characterise an exoplanetary system
Authors: Bonfanti A. , Gillon M.
Published: January 2020

Context.Useful information can be retrieved by analysing the transit light curve of a planet-hosting star or induced radial velocity oscillations. However, inferring the physical parameters of the planet, such as mass, size, and semi-major axis, requires preliminary knowledge of some parameters of the host star, especially its mass or radius, which are generally inferred through theoretical evolutionary models.

Aims.We seek to present and test a whole algorithm devoted to the complete characterisation of an exoplanetary system thanks to the global analysis of photometric or radial velocity time series combined with observational stellar parameters derived either from spectroscopy or photometry.

Methods.We developed an integrated tool called MCMCI. This tool combines the Markov chain Monte Carlo (MCMC) approach of analysing photometric or radial velocity time series with a proper interpolation within stellar evolutionary isochrones and tracks, known as isochrone placement, to be performed at each chain step, to retrieve stellar theoretical parameters such as age, mass, and radius.

Results.We tested the MCMCI on the HD 219134 multi-planetary system hosting two transiting rocky super Earths and on WASP-4, which hosts a bloated hot Jupiter. Even considering different input approaches, a final convergence was reached within the code, we found good agreement with the results already stated in the literature and we obtained more precise output parameters, especially concerning planetary masses.

Conclusions.The MCMCI tool offers the opportunity to perform an integrated analysis of an exoplanetary system without splitting it into the preliminary stellar characterisation through theoretical models. Rather this approach favours a close interaction between light curve analysis and isochrones, so that the parameters recovered at each step of the MCMC enter as inputs for purposes of isochrone placement.
Ionized gas kinematics of massive elliptical galaxies in CALIFA and in cosmological zoom-in simulations
Authors: Florian Jan , Ziegler Bodo , Hirschmann Michaela , Papaderos Polychronis , Choi Ena , Frigo Matteo , Gomes Jean-Michel , Somerville Rachel S.
Published: January 2020

Context.Powerful active galactic nuclei (AGN) are supposed to play a key regulatory role on the evolution of their host galaxies by shaping the thermodynamic properties of their gas component. However, little is known as to the nature and the visibility timescale of the kinematical imprints of AGN-driven feedback. Gaining theoretical and observational insights into this subject is indispensable for a thorough understanding of the AGN-galaxy coevolution and could yield empirical diagnostics for the identification of galaxies that have experienced a major AGN episode in the past.

Aims.We present an investigation of kinematical imprints of AGN feedback on the warm ionized gas medium (WIM) of massive early-type galaxies (ETGs). To this end, we take a two-fold approach that involves a comparative analysis of Hαvelocity fields in 123 local ETGs from the CALIFA (Calar Alto Legacy Integral Field Area Survey) integral field spectroscopy survey with 20 simulated galaxies from high-resolution hydrodynamic cosmological SPHgal simulations. The latter were resimulated for two modeling setups, one with and another without AGN feedback.

Methods.In order to quantify the effects of AGN feedback on gas kinematics, we measured three parameters that probe deviations from simple regular rotation by using the kinemetry package. These indicators trace the possible presence of distinct kinematic components in Fourier space (k3, 5/k1), variations in the radial profile of the kinematic major axis (σPA), and offsets between the stellar and gas velocity fields (Δϕ). These quantities were monitored in the simulations from a redshift 3 to 0.2 to assess the connection between black hole accretion history, stellar mass growth, and the kinematical perturbation of the WIM.

Results.Observed local massive galaxies show a broad range of irregularities, indicating disturbed warm gas motions, which is irrespective of being classified via diagnostic lines as AGN or not. Simulations of massive galaxies with AGN feedback generally exhibit higher irregularity parameters than without AGN feedback, which is more consistent with observations. Besides AGN feedback, other processes like major merger events or infalling gas clouds can lead to elevated irregularity parameters, but they are typically of shorter duration. More specifically,k3, 5/k1is most sensitive to AGN feedback, whereas Δϕis most strongly affected by gas infall.

Conclusions.We conclude that even if the general disturbance of the WIM velocity is not a unique indicator for AGN feedback, irregularity parameters that are high enough to be consistent with observations can only be reproduced in simulations with AGN feedback. Specifically, an elevated value for the deviation from simple ordered motion is a strong sign for previous events of AGN activity and feedback.
A hyper luminous starburst at z = 4.72 magnified by a lensing galaxy pair at z = 1.48
Authors: Ciesla L. , Béthermin M. , Daddi E. , Richard J. , Diaz-Santos T. , Sargent M. T. , Elbaz D. , Boquien M. , Wang T. , Schreiber C. , Yang C. , Zabl J. , Fraser M. , Aravena M. , Assef R. J. , Baker A. J. , Beelen A. , Boselli A. , Bournaud F. , Burgarella D. , Charmandaris V. , Côté P. , Epinat B. , Ferrarese L. , Gobat R. , Ilbert O.
Published: January 2020

We serendipitously discovered in the Herschel Reference Survey an extremely bright infrared source with S500 ∼ 120 mJy in the line of sight of the Virgo cluster which we name Red Virgo 4 (RV4). Based on IRAM/EMIR and IRAM/NOEMA detections of the CO(5−4), CO(4−3), and [CI] lines, RV4 is located at a redshift of 4.724, yielding a total observed infrared luminosity of 1.1 ± 0.6 × 1014 L⊙. At the position of the Herschel emission, three blobs are detected with the VLA at 10 cm. The CO(5−4) line detection of each blob confirms that they are at the same redshift with the same line width, indicating that they are multiple images of the same source. In Spitzer and deep optical observations, two sources, High-z Lens 1 (HL1) West and HL1 East, are detected at the center of the three VLA/NOEMA blobs. These two sources are placed at z = 1.48 with X-shooter spectra, suggesting that they could be merging and gravitationally lensing the emission of RV4. HL1 is the second most distant lens known to date in strong lensing systems. Constrained by the position of the three VLA/NOEMA blobs, the Einstein radius of the lensing system is 2.2″ ± 0.2 (20 kpc). The high redshift of HL1 and the large Einstein radius are highly unusual for a strong lensing system. In this paper, we present the insterstellar medium properties of the background source RV4. Different estimates of the gas depletion time yield low values suggesting that RV4 is a starburst galaxy. Among all high-z submillimeter galaxies, this source exhibits one of the lowest L[CI] to LIR ratios, 3.2 ± 0.9 × 10−6, suggesting an extremely short gas depletion time of only 14 ± 5 Myr. It also shows a relatively high L[CI] to LCO(4−3) ratio (0.7 ± 0.2) and low LCO(5−4) to LIR ratio (only ∼50% of the value expected for normal galaxies) hinting at low density of gas. Finally, we discuss the short depletion time of RV4. It can be explained by either a very high star formation efficiency, which is difficult to reconcile with major mergers simulations of high-z galaxies, or a rapid decrease of star formation, which would bias the estimate of the depletion time toward an artificially low value.
HD 117214 debris disk: scattered-light images and constraints on the presence of planets
Authors: Engler N. , Lazzoni C. , Gratton R. , Milli J. , Schmid H. M. , Chauvin G. , Kral Q. , Pawellek N. , Thébault P. , Boccaletti A. , Bonnefoy M. , Brown S. , Buey T. , Cantalloube F. , Carle M. , Cheetham A. , Desidera S. , Feldt M. , Ginski C. , Gisler D. , Henning Th. , Hunziker S. , Lagrange A. M. , Langlois M. , Mesa D. , Meyer M. R. , Moeller-Nilsson O. , Olofsson J. , Petit C. , Petrus S. , Quanz S. P. , Rickman E. , Stadler E. , Stolker T. , Vigan A. , Wildi F. , Zurlo A.
Published: January 2020

Context. Young stars with debris disks are the most promising targets for an exoplanet search because debris indicate a successful formation of planetary bodies. Debris disks can be shaped by planets into ring structures that give valuable indications on the presence and location of planets in the disk.

Aims. We performed observations of the Sco-Cen F star HD 117214 to search for planetary companions and to characterize the debris disk structure.

Methods. HD 117214 was observed with the SPHERE subsystems IRDIS, IFS, and ZIMPOL at optical and near-IR wavelengths using angular and polarimetric differential imaging techniques. This provided the first images of scattered light from the debris disk with the highest spatial resolution of 25 mas and an inner working angle <0.1″. With the observations with IRDIS and IFS we derived detection limits for substellar companions. The geometrical parameters of the detected disk were constrained by fitting 3D models for the scattering of an optically thin dust disk. Investigating the possible origin of the disk gap, we introduced putative planets therein and modeled the planet–disk and planet–planet dynamical interactions. The obtained planetary architectures were compared with the detection limit curves.

Results. The debris disk has an axisymmetric ring structure with a radius of 0.42(±0.01)″ or ~45 au and an inclination of 71(±2.5)° and exhibits a 0.4″ (~40 au) wide inner cavity. From the polarimetric data, we derive a polarized flux contrast for the disk of (Fpol)disk/F∗ = (3.1 ± 1.2) × 10−4 in the RI band.

Conclusions. The fractional scattered polarized flux of the disk is eight times lower than the fractional IR flux excess. This ratio is similar to the one obtained for the debris disk HIP 79977, indicating that dust radiation properties are similar for these two disks. Inside the disk cavity we achieve high-sensitivity limits on planetary companions with a mass down to ~4 MJ at projected radial separations between 0.2″ and 0.4″. We can exclude stellar companions at a radial separation larger than 75 mas from the star.
Peculiar emission line spectra of core extremely red BOSS quasars at z∼2–3: orientation and/or evolution?
Authors: Villar Martín M. , Perna M. , Humphrey A. , Castro Rodríguez N. , Binette L. , Pérez González P. G. , Mateos S. , Cabrera Lavers A.
Published: January 2020

Context. Core extremely red quasars (core ERQ) have been proposed to represent an intermediate evolutionary phase in which a heavily obscured quasar blows out the circumnuclear interstellar medium with very energetic outflows before it becomes an optical quasar.

Aims. We investigate whether the properties of core ERQ fit the AGN orientation-based unification scenario.

Methods. We revised the general UV and optical emission line properties of core ERQ in the context of the orientation-based scenario. We used diagnostic diagrams based on UV emission line ratios and UV-to-optical line kinematic information to compare the physical and kinematic gas properties of core ERQ with those of other luminous narrow- and broad-line AGN. In particular, we provide a revised comparison of the [OIII] kinematics in 21 core ERQ (20 from Perrotta et al. 2019, MNRAS, 488, 4126 and SDSS J171420.38+414815.7, based on GTC EMIR near-infrared spectroscopy) with other samples of quasars with matching luminosity with the aim of evaluating whether core ERQ host the most extreme [OIII] outflows.

Results. The UV line ratios suggest that the physical properties (e.g., density and metallicity) of the ionised gas in core ERQ are similar to those observed in the broad-line region of blue nitrogen-loud quasars. The [OIII] outflow velocities of core ERQ are on average consistent with those of very luminous blue type 1 quasars, although extreme outflows are much more frequent in core ERQ. These similarities can be explained in the context of the AGN unification model under the assumption that core ERQ are viewed with an intermediate orientation between type 2 (edge-on) and type 1 (face-on) quasars.

Conclusions. We propose that core ERQ are very luminous but otherwise normal quasars viewed at an intermediate orientation. This orientation allows a direct view of the outer part of the large broad-line region from which core ERQ UV line emission originates; the extreme [OIII] outflow velocities are instead a consequence of the very high luminosity of core ERQ.
The strange case of the peculiar spiral galaxy NGC 5474
Authors: Bellazzini M. , Annibali F. , Tosi M. , Mucciarelli A. , Cignoni M. , Beccari G. , Nipoti C. , Pascale R.
Published: January 2020

We present the first analysis of the stellar content of the structures and substructures identified in the peculiar star-forming galaxy NGC 5474, based on Hubble Space Telescope resolved photometry from the LEGUS survey. NGC 5474 is a satellite of the giant spiral M 101, and it is known to have a prominent bulge that is significantly off-set from the kinematic centre of the underlying H I and stellar disc. The youngest stars (age ≲ 100 Myr) trace a flocculent spiral pattern extending out to ≳8 kpc from the centre of the galaxy. On the other hand, intermediate-age (age ≳ 500 Myr) and old (age ≳ 2 Gyr) stars dominate the off-centred bulge and a large substructure residing in the south-western part of the disc (SW over-density) and they are not correlated with the spiral arms. The old age of the stars in the SW over-density suggests that this may be another signature of any dynamical interactions that have shaped this anomalous galaxy. We suggest that a fly by with M 101, generally invoked as the origin of the anomalies, may not be sufficient to explain all the observations. A more local and more recent interaction may help to put all the pieces of this galactic puzzle together.
Aspects regarding the applicability of ATEX directives for the evaluation of products regarding the risk of explosion
Authors: Părăian Mihaela , Burian Sorin , Vătavu Niculina , Păun Florin
Published: January 2020

Current legislation regulates the obligations and responsibilities of persons who perform design, manufacture and use of equipment and installations in potentially explosive atmospheres with regard to compliance with explosion prevention requirements. There are two European Directives, so-called ATEx Directives, which regulate the placing on the European market of products intended for use in potentially explosive atmospheres and their safe use: Directive 2014/34/EU and Directive 1999/92/EC. The paper presents some aspects regarding the border situations where the two directives apply, in the case of assemblies of equipment to be assessed by a manufacturer in accordance with the Directive 2014/34/EU for putting on the market and the installations that are equipment assembled by the user under his responsibility and have to be assessed by users toward with the Directive 1999/92/EC requirements.
Best practices to improve construction site safety, in the specific conditions of processing plant building
Authors: Vladkova Blagovesta
Published: January 2020

Construction and installation work at large industrial sites are a major challenge both in terms of meeting deadlines and ensuring healthy and safe working conditions. Force majeure circumstances that require rapid and adequate response often occur at complex sites. Construction site safety is one of the most important things during a construction project. The main reason is the accidents that occur. Presented paper’s target is to shed more light on some good practices, which can lead to improved occupational health and safety. Author experienced such practices in specific conditions during processing plant construction. Such facilities are characterized by installation of special large-scale mineral processing equipment, including work in explosive atmosphere. Moreover, outdoor work in severe weather conditions is performed very often. Another very important, and at the same time difficult task, is coordinating many people, working for contractors and subcontractors. Some of the most important factors in such practice, which have a key role in the successful realization of that type of project will be discussed.
Computational simulation of safety parameters concerning friction and impact sensitivity of tested civil use explosives
Authors: Jitea Ilie Ciprian , Laszlo Robert , Rus Daniela , Ilici Ştefan , Miclea Olga
Published: January 2020

The paper presents the results of the theoretical and practical researches regarding the development of conceptual and experimental models specific to the determination of the safety parameters regarding the friction and impact sensitivity, whose plausibility be guaranteed through a whole range of scientific solutions characterized by validated results through numerical modeling and simulations. Designing these types of processes requires consideration, with a relative approximation, the degree of danger due to the design of fragments resulting from detonation, vibrations, pressures, tensions created in the space affected by the explosion, explosion gas generation etc. Estimating the peak values of induced requests is an essential for implementing IT solutions of previous experimentation allows the study of a large number of scenarios, the limit being mainly dependent on the time spent on computer simulations. In this context, safety research into the handling of explosives, the acquisition of experience and knowledge as well as the validation of results by comparison with previous practical experiments and those specified in the literature, become relevant and necessary requirements. Methods used to determine security parameters, analyzed by classical and IT means are relevant to the interpretation of the nature of the explosive matter in terms of their effect in terms of the effect they may have on the environment of use in the event of an explosion in accordance with the legislation in force an important indicator of classification, handling, storage and transport in the assessment and the management of the risks associated with these operations. The paper presents a series of results regarding computer numerical simulations, safety parameters (friction and impact sensitivity). The similarity of the results obtained in the case of physical experiments to determine the susceptibility of explosive substances tested to friction and impact stimuli in relation to those provided by computerized numerical simulations demonstrate the usefulness of these IT science solutions that through the ANSYS Multiphysics package provide the prerequisites for determining the safety features in the field of explosives for civilian use.
Defining parameters for numerical modelling of fires
Authors: Vass Zoltan , Şimon-Marinică Adrian Bogdan , Stănilă Sorina
Published: January 2020

Fires caused by human activities are one of the main causes of losses in terms of both human lives and material and economic capital. To prevent these losses, it is necessary to perform the needed activities of research in the area of industrial fires, as such one of the methods of achieving this, is to perform computer aided numerical simulations of fires. By this process of computational modelling, we can determine the causes of the fires, and the mechanism by which the fire has propagated and developed. Also, numerical modelling of fires, can help in the development of procedures, and norms, which we can implement, to protect the personnel and to prevent material and economic losses.
Designing and using robots for performing inspections in potentially explosive atmospheres
Authors: Colda Cosmin , Burian Sorin
Published: January 2020

Directive 2014/34/EU ATEx regulates the placement on the European market of equipment and technical installations for use in potentially explosive atmospheres. The current article has as purpose to present the manner of choosing types of protection for designing robots intended to be used for performing inspections in atmospheres with explosion hazard. The safety of workers has led to the development of technologies required for simplifying and safe performance of inspections in areas with explosion hazard.
Environmental impact of methane released from coal mines
Authors: Ianc Nicolae , Boantă Corneliu , Gherghe Ion , Tomescu Cristian
Published: January 2020

Methane gas accompanying coal deposits was formed as a result of successive stages of the anaerobic process of vegetal material transformation into coal, at high temperatures and pressures, without external oxygen supply. During the metamorphism process, the content of C, H and O is modified, meaning an increase in carbon content, a decrease in hydrogen and oxygen, the nitrogen and sulphur content remaining constant. During this process, water and carbon dioxide is generated, the water being generated in the first transformation phases. Within the slow oxidation process, gas products result by using the oxygen content in plants, especially methane and carbon dioxide due to the fermentation stimulated by bacteria. Methane released into the atmosphere following the mining of coal have double ecological impact, participating in the destruction of the ozone layer and at the same time contributing to the enhancement of the greenhouse effect. At the same time, methane gas released into the atmosphere during coal mining may be used by mining operators as primary power resource for covering the power requirements of the mine or it can be used for commercial purposes.
Influence of the flooding speed of former lignite open pits on the stability of final slopes
Authors: Lazăr Maria , Faur Florin , Apostu Izabela Maria
Published: January 2020

Flooding the residual gaps of former lignite open pits is often applied worldwide, offering opportunities for the use of the lake and the reclaimed land, as well as many benefits, ranging from the restoration of ecosystems to the development of the local economy. The flooding process is conditioned by the available quantities of water from natural and/or artificial sources. Flooding can be done either by natural methods (underground water inflow plus intake of water from rainfall and superficial drainage), or by natural and artificial methods (water adductions from superficial collectors). Unlike artificial flooding, natural flooding has the advantage of reduced costs, but it is a long-lasting process. Depending on the flooding speed, as a result of rising water level and saturation of rocks from the final slopes, geotechnical phenomena such as landslides may occur. The paper aims at establishing the dependence between the rhythm of raising the water level in the lake and the geotechnical behavior of the rock in the internal dump. Depending on this, there is a need to accelerate the flooding process through adductions, as the hydrostatic pressure manifested on the final slopes determines the increase of their stability reserve.
LoRa communication and geolocation system for sensors network
Authors: Rus Cosmin , Leba Monica , Marcuş Răzvan , Pellegrini Lilla , Costandoiu Alin
Published: January 2020

The Internet of Things (IoT) has developed tremendously over the past few years and has proven its worth in many areas of activity. With regard to environmental air quality monitoring, there are more and more products and applications that try to gather as much data as possible about all the pollution factors in a given area. This paper aims to present a new method of using devices capable of communicating with each other using the LoRa communication protocol to report to a real-time central server on environmental air quality. The innovation of this paper is the fact that it is implemented using a developed LoRa localization protocol, which connects an air quality sensor network, using only the low power of the LoRa technology by applying a multilayer algorithm to the gateway timestamps from received packages. The so created LoRaWAN tracking system is able to exploit transmitted packets to calculate the current position without using GPS or GSM that are high power consumers.
Managemnet of revegetation of the slag and ash deposits of the Paroseni Thermoelectric Power Plant
Authors: Tataru Andreea Cristina , Stanci Aurora , Tataru Dorin , Radu Mihai Sorin , Rus Ioan
Published: January 2020

As a result of the combustion of coal in the Paroseni Thermal Power Plant, large amounts of slag and ash waste are produced. Slag and ashes are deposited in the Caprisoara Valley slag and ash deposits. Upon completion of the deposit process, these landfills must be cleaned and reintroduced in natural circuit. An important step in the process of reintroduction in natural circuit of the deposits of slag and ashes is the implementation of some methods of revegetation. The chosen method must respect the main objectives of an environmental management system. In this paper we will present a method for managing the process of revegetation of the slag and ash deposits in order to reintroduce affected areas into the natural circuit.
Measuring the change of air temperature with 8 LM75A sensors in mining area
Authors: Stanimirescu Alexandra , Egri Angela , Soica Florin Flavius , Radu Sorin Mihai
Published: January 2020

The studied geographical area is situated in a intramontane region situated on the Jiu River called the Jiu Valley, where the main economic activity is mining. The importance of studying this area is related to the effect of coal mining on the climate. Coal extraction in the area led to a change of atmospheric temperature due to the emissions of gases and dust that affects the environment. The use of LM75A sensors allow us to accurately read the air temperature and transmit warning messages when certain temperature intervals are exceeded.
Research on the improvement of test methods for the determination of dust penetration in enclosures of equipment intended for explosive atmospheres
Authors: Vătavu Niculina , Jurca Adrian , Vătavu Sorin , Gabor Dan
Published: January 2020

Carcasses of electrical or non-electrical equipment operating in potentially explosive atmospheres must provide a certain degree of protection against access to hazardous parts, penetration of solid bodies and/or water penetration, which must be tested according to the specifications of the Ex protection types. Normal protection classes are indicated by the international IP code followed by two characteristic digits referring to the protection against penetration of solid foreign bodies and water protection, followed by optional letters if required by the beneficiary according to the imposed conditions of use. Within the ENExEMEIP laboratory, have been developed laboratory tests to verify the first characteristic figure of the standard degree of protection according to the standardized European method. In the paper is presented the test stand of the large gauge equipment, a stand made with state-of-the-art equipment that provides the necessary performance for the accreditation of the test according to the standardized requirements. Checking dustproof protection to equipment used in areas where explosive atmospheres generated by combustion dust may occur is particularly important for assessing compliance with the requirements of the ATEX Directive [5], as this protection is a basic requirement for explosion protection.
Safety, health and hazards related to using of sprayed concrete in underground mining works
Authors: Toderaş Mihaela , Danciu Ciprian
Published: January 2020

Sprayed concrete is a traditional building material, but at the same time it represents a highly innovative technology. The development of sprayed concrete includes material science and advances spraying equipment technology. The performance and characteristics of sprayed concrete depend mainly on the condition of its application, equipments, experience and competence of the crew performing the sprayed concrete operation. This paper presents some aspects regarding a sprayed concrete operation that may have multiple hazards due to the equipment, pressure value and the projection of rebound. In addition, the use of sprayed concrete in underground mining works, involve an adequate ventilation in the application area. Special attention has to be given to chemical admixtures and complementary products use in the constituent materials and finally, in the composition of sprayed concrete.
Technical and safety aspects at the demolition by blasting works of a cooling tower with a high of 72.00 m
Authors: Laszlo Robert , Radeanu Cristian , Ilici Stefan , Grecea Mircea , Levente Miklos
Published: January 2020

From the point of view of demolition, one of the most interesting construction categories is the hyperboloid shape cooling towers. These seemingly fragile structures support at the base on a reinforced concrete belt and pillars. An important element to be taken into account when choosing the demolition solution is the slope of the tower. As this ratio between tower height and base diameter is greater (4-5), the easier is the demolition of the tower by overturning, respectively by moving the centre of gravity of the construction away from its base. In the case of the cooling tower described in this article, its height was 72.00 m and the base diameter of 52.00 m - the slope ratio index being less than 2, which was why the chosen solution of demolition was that of partial lateral collapse followed by a total crash of the tower on its position. The article describes how to perform the demolition of the cooling tower, the technical and safety solutions adopted for its successful collapse in the intended direction, in very sensitive location conditions regarding the constructions and installations in its immediate vicinity.
The role of powered support in ensuring the proper longwall working cross-section area in rockburst-prone seams
Authors: Lubosik Zbigniew , Rajwa Sylwester , Walentek Andrzej , Masny Wojciech , Wrana Aleksander
Published: January 2020

In Poland, for underground hard coal seam extraction, the longwall method is used. Retreat longwalls with natural roof caving in the gob are the most common. Currently it is estimated that about a half of the hard coal output in Poland originates from seams located in areas of rock burst hazard. The article shows information about 18 rock bursts, and 14 other seismic events which occurred between 2003 and 2012 in underground mines belonging to one of coal companies in Poland. In addition, negative consequences of those dynamic phenomena in the longwall workings are described. In the next part of paper, the most common types of damage to powered supports after the rock mass tremors and other dynamic phenomena in longwall workings are shown. In order to avoid damage of powered supports, in geo-mining conditions where dynamic phenomena occur, different types of protective means are applied. In the paper the methodology of assessing the powered support yield ability is described. At the end, an example of the assessed yield ability of a powered support in given geo-mining conditions of a longwall face affected by the seismic events is presented.
Using the event tree analysis in the investigation of a work accident
Authors: Mares Radu Emil , Nagy Mariana , Radu Ioan
Published: January 2020

Work accidents occur when the system doesn’t work properly and the safety barriers are avoided. The analysis of such events can be made by different methods. This paper aims at demonstrating how a work accident can be investigated by the use of the Events’ Tree decision method. Applying the steps of the algorithm, the method leads to determinate the causes of a work accident that occurs during the starting procedure of an equipment. By building the events’ tree, a graphical representation of the operations and decisions lead to a logical framework that explains the work accident. The case study consists of the description, analysis, investigation and mitigation of a work accident that occurred at the Rehabilitation of a road in Arad County. Using the Events’ Tree decision method, the cause of the accident was found to be the weak training of the operator and the carelessness of the job manager.
Water reuse as a secure pathway to deal with water scarcity
Authors: Torretta Vincenzo , Katsoyiannis Ioannis , Collivignarelli Maria Cristina , Bertanza Giorgio , Xanthopoulou Maria
Published: January 2020

An adequate access to water supply systems is crucial for a sustainable future. Climate change is expected to increase water shortage problems worldwide. Reuse/recycling of treated wastewater for domestic and/or agricultural purposes can be considered an interesting water supply: it is independent from seasonal drought and meteorological variability and able to cover the peak of water demand. In the case of direct reuse, the parameter of treated water must comply with the reuse limits for biological oxygen demand, chemical oxygen demand and suspended solids. In case of indirect reuse, the regulatory approach changes as the dilution ratio between discharge and flow of the irrigation canal is taken into account too. There are many interventions that are considered useful for the purpose of promoting the development of an enhanced water recovery and recycling: legislation improvements, modification in the water storage management, prevention in pollution discharged into sewerage systems, improving the efficiency of WWTPs, incentive the adoption of rainwater storage tanks and interventions for the separation of gray water, establish a “blue certificate” for financing investments. In the present paper those aspects are analysed referring to some cases found in an Italian region.
Why do the psycho-social conditions in the field of mining require changes to occupational health and safety legislation?
Authors: Albulescu Andrei-George , Bejinariu Costică , Popescu Ioan , Baciu Constantin , Bernevig-Sava Mihai-Adrian
Published: January 2020

In 2019, 13 years have passed since the adoption of Law no. 319/2006 on Safety and Health at Work. Analysing the conditions of its application, there is a clear need to change, to correct some structural deficiencies and to reformulate various terms and definitions. The „ad literam” translation of the Council Directive 89/391/EEC has led to the forced introduction of some terms (e.g. designated worker, external service, light accident) or the ambiguous formulation of some requirements (e.g.: the situations in which the employer resorts to external services). The authors formulate proposals that will lead to the improvement of mining activities: - the obligation to undergo psychological examination, upon hiring and periodically, as a result of intensification of the general stress conditions and the effects of the special activities conducted underground; - determining the number of specialists in the field of occupational safety and health, depending on the number of employees in the respective enterprise; - the investigation of all work related accidents by the Territorial Labour Inspectorates, respectively the Labour Inspectorate, in order to avoid the conflict of interests during their investigation and to have a correct record of them, including in the mining activities.
Using PC indices to predict violent GIC events threatening power grids
Authors: Stauning Peter
Published: January 2020

The aim of the present contribution is to investigate the timing relations between enhancements in the Polar Cap (PC) indices and power grid disturbances related to geomagnetically induced currents (GIC). The polar cap indices, PCN (North) and PCS (South), are based on measurements of geomagnetic variations in the central polar caps. These variations are strongly related to the transpolar convection of plasma and magnetic fields driven by the solar wind. During cases of enhanced merging processes at the front of the magnetosphere and subsequent tailward convection of plasma and embedded magnetic fields, the magnetospheric tail configuration may accumulate excess energy, which upon release may cause violent substorm activity. Earlier reports have disclosed remarkably lengthy intervals, ranging up to several hours, of elevated PC index values preceding GIC-related power grid disruptions. The present investigation has shown that the delays of typically 3–4 h between increases in the PC indices and GIC-related power grid disturbances are related to displacements of the substorm processes responsible for strong GIC events to subauroral latitudes where vulnerable power grids reside. The results have shown that PC index values remaining above an “alert level” of 10 mV/m through more than 1 h indicate a high risk for violent GIC events that may threaten power grids and other vulnerable technical systems. These results support the application of real-time PC indices in space weather monitoring and forecast services.
Wenn Helfer Hilfe brauchen
Authors: Koch Sebastian
Published: January 2020

Wenn irgendwo auf der Welt eine Epidemie ausbricht und viele Menschen erkranken, ist internationales Eingreifen von Hilfskräften nötig, darunter auch Ärzte und Pflegekräfte. Doch was geschieht, wenn diese Helfer sich selbst anstecken?
Schmerzhafte artifizielle Ekchymosen an Hals und Gesicht
Authors: Markovic A. , Simon J. C. , Kirsten H. L. , Kunz M.
Published: January 2020

Es wird über den Fall einer 13-jährigen Patientin mit neu aufgetretenen, auf Druck schmerzhaften Hautveränderungen beidseits am Hals und im Gesicht berichtet. Auf Nachfrage traten die Effloreszenzen episodisch im Rahmen von Stresssituationen auf. Im Verlauf kam es zu einer Spontanheilung mit Narbenbildung und mehreren Rezidiven. Nach erfolgter Probebiopsie wurde ein Gardner-Diamond-Syndrom ausgeschlossen und der Verdacht auf selbstinduzierte Hautläsionen geäußert.