scholarly journals Experimental Study of Pyrite Oxidation at 100 °C: Implications for Deep Geological Radwaste Repository in Claystone

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 427 ◽  
Author(s):  
Héloïse Verron ◽  
Jérôme Sterpenich ◽  
Julien Bonnet ◽  
Franck Bourdelle ◽  
Régine Mosser-Ruck ◽  
...  
Keyword(s):  
Oxidation Rate ◽  
Carbonic Acid ◽  
Near Field ◽  
Pyrite Oxidation ◽  
Thermodynamic Modelling ◽  
Stable Phase ◽  
Native Sulfur ◽  
Kinetic Effects ◽  
Pco2 Monitoring ◽  
Set Up

The oxidation of pyrite is one of the near field processes of the chemical evolution of clay rock planned to host a deep geological radioactive waste repository during operation. Indeed, this process can lead to transitory acidic conditions in the medium (i.e., production of sulphuric acid, carbonic acid) which may influence the corrosion kinetics of the carbon steel components of some disposal cells. In order to improve the geochemical modelling of the long-term disposal, the oxidation of pyrite in contact with clays and carbonates at 100 °C must be evaluated. In this study, special attention was paid to the pyrite oxidation rate thanks to an original experimental set-up, involving several pyrite/mineral mixtures and a reactor coupled to a micro gas chromatograph (PO2 and PCO2 monitoring). Although thermodynamic modelling expects that hematite is the most stable phase in a pure pyrite heated system (low pH), experiments show the formation of native sulfur as an intermediate product of the reaction. In the presence of calcite, the pH is neutralized and drives the lower reactivity of pyrite in the absence of native sulfur. The addition of clay phases or other detrital silicates from the claystone had no impact on pyrite oxidation rate. The discrepancies between experiments and thermodynamic modelling are explained by kinetic effects. Two laws were deduced at 100 °C. The first concerns a pure pyrite system, with the following law: r P y =   10 − 4.8 · P O 2 0.5 · t − 0.5 . The second concerns a pyrite/carbonates system: r P y + C a =   10 − 5.1 · P O 2 0.5 · t − 0.5 where PO2 corresponds to the partial pressure of O2 (in bar) and t is time in seconds. Different mechanisms are proposed to explain the evolution with time of the O2 consumption during pyrite oxidation: (i) decrease of the specific or reactive surface area after oxidation of fine grains of pyrite, (ii) decrease of O2 pressure, (iii) growing up of secondary minerals (Fe-oxides or anhydrite in the presence of calcium in the system) on the surface of pyrite limiting the access of O2 to the fresh surface of pyrite, and (iv) change in the pH of the solution.

Numerical Simulation of Viscous Jet for Near-Field Electrospinning

2009 ◽  
Vol 60-61 ◽  
pp. 465-469 ◽  
Author(s):  
Yuan Yuan Zhong ◽  
Gao Feng Zheng ◽  
Dao Heng Sun
Keyword(s):  
Numerical Simulation ◽  
Field Strength ◽  
Process Parameters ◽  
Near Field ◽  
Solution Concentration ◽  
Electrospinning Process ◽  
Substrate Distance ◽  
Viscous Jet ◽  
Set Up ◽  
The Impact

Near-Field Electrospinning (NFES) is a newly developed method to fabricate continuous and ordered solid nanofibers, with smaller spinneret-to-collector-distance the behavior of viscous jet would play a more prominent effect on the deposition and morphology of nanofiber. In this paper, a 2-dimentional physical model based on electrohydrodynamics and rheology was set up to discuss the morphology of viscous jet for NFES. The profile of the jet along z direction can be predicted by this model, and the impact of process parameters on the jet radius is analyzed. Radius of jet decreases with spinneret-to-substrate-distance decreasing; jet radius decreases with applied voltage and electric field strength increasing; jet electrospun from PEO solution is thinner than that from PVA solution with the same solution concentration; solution concentration has insignificant influence on the radius of jet from solution of the same polymer (PVA or PEO). This numerical simulation would improve the control of electrospinning process in NFES.

scholarly journals Performance Evaluation of a Novel Animals Tracking System based on UHF RFID Technology

2013 ◽  
Vol 9 (1) ◽  
pp. 4 ◽  
Author(s):  
Luca Catarinucci ◽  
Luigi Patrono
Keyword(s):  
Radio Frequency Identification ◽  
Tracking System ◽  
Near Field ◽  
Uhf Rfid ◽  
Wide Range ◽  
Frequency Identification ◽  
Set Up ◽  
Received Signal Strength Indication ◽  
Localization And Tracking ◽  
Localization Data

The adoption of solutions based on Radio Frequency IDentification technology in a wide range of contexts is a matter of fact. In many situations, such as the tracking of small-size living animals, the straightforward use of commercial systems does not ensure adequate performance. Consequently, both the RFID hardware and the software control platform should be tailored for the particular application. In this work, the specific requirements of Near Field Ultra High Frequency RFID reader antennas suitable for small-size animal localization and tracking are identified and a control system in a LabVIEW environment is designed. Afterwards, both hardware and software solutions have been implemented and validated. In particular, an algorithm based on the measured Received Signal Strength Indication, in order to obtain precise localization data, was developed and validated. Finally, the set-up of a first working prototype involving built-in-lab reader antennas has been completed and tested. The achieved results prove the effectiveness of the proposed tracking system.

Experimental Study of the Temperature Field Equation in the Leeward Tunnel during Mine Fire Period

2012 ◽  
Vol 588-589 ◽  
pp. 1842-1848
Author(s):  
Wen Cai Wang ◽  
Yu Hong Jiang ◽  
Tao Hou ◽  
Wei Liu ◽  
Yang Lu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Temperature Field ◽  
Field Equation ◽  
Wind Speed ◽  
Stable Phase ◽  
Measuring Point ◽  
Mine Fire ◽  
Mine Roadway ◽  
Set Up

According to the principle of heat transfer, the temperature field equation in the leeward tunnel was set up and the experimental device with a ratio of 1:20 was built. When it happened to fire in roadway, the correctness of the temperature field equation can be verified by the experiment. In experiments, the armored thermocouple and color paperless recorder were used to record the temperature of each measuring point. The S-3-300 pitot tube and YJB-2500 compensation micro-manometer were used to determine the wind speed. When the mine roadway fired, the experiment determined the temperature field equation experiment coefficient of Kc. It showed that in the developing phase of the fire Kc= 15 ~ 20, in the stable phase of the fire Kc= 10 ~ 15, in the failing phase of the fire Kc= 20 ~ 25.

scholarly journals Conservative transport of dissolved sulfate across the Rio Madre de Dios floodplain in Peru

Geology ◽  
2021 ◽  
Author(s):  
Emily I. Burt ◽  
Markus Bill ◽  
Mark E. Conrad ◽  
Adan Julian Ccahuana Quispe ◽  
John N. Christensen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Stable Isotope ◽  
Carbonic Acid ◽  
Isotope Composition ◽  
Sulfide Oxidation ◽  
Pyrite Oxidation ◽  
Sulfide Mineral ◽  
Mineral Weathering ◽  
Primary Role ◽  
Peruvian Andes

Mineral weathering plays a primary role in the geologic carbon cycle. Silicate weathering by carbonic acid consumes CO2 and stabilizes Earth’s climate system. However, when sulfuric acid drives weathering, CO2 can be released to the atmosphere. Recent work has established that sulfuric acid weathering resulting from sulfide mineral oxidation is globally significant and particularly important in rapidly eroding environments. In contrast, if SO42– produced by sulfide oxidation is reduced during continental transit, then CO2 release may be negated. Yet, little is known about how much SO42– reduction takes place in terrestrial environments. We report oxygen and sulfur stable isotope ratios of SO42– in river waters and mass budget calculations, which together suggest that SO42– released from pyrite oxidation in the Peruvian Andes mountains is conservatively exported across ~300 km of the Amazon floodplain. In this system, floodplain SO42– reduction does not counteract the large SO42– flux from Andean pyrite weathering or measurably affect the stable isotope composition of riverine SO42–. These findings support the hypothesis that uplift and erosion of sedimentary rocks drive release of CO2 from the rock reservoir to the atmosphere.

scholarly journals Validation of numerical methods for electromagnetic dosimetry through near-field measurements

ACTA IMEKO ◽  
2015 ◽  
Vol 4 (1) ◽  
pp. 90 ◽  
Author(s):  
Domenico Giordano ◽  
Luca Zilberti ◽  
Michele Borsero ◽  
Roberto Forastiere ◽  
Wencui Wang
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Field ◽  
Electromagnetic Field ◽  
Boundary Element Method ◽  
Near Field ◽  
Larmor Frequency ◽  
Field Measurements ◽  
Magnetic Element ◽  
Resonance Imaging ◽  
Set Up

This paper describes the arrangement of a first experimental set-up which allows the comparison between the measurement of the electromagnetic field quantities induced inside a simple cylindrical phantom and the same quantities estimated numerically through a boundary element method. The reliability of the numerical method has been tested at 64 MHz, the Larmor frequency associated to the magnetic resonance imaging devices with an isocenter magnetic field of 1.5 T. To assess its robustness, the comparison is also performed by introducing, inside the phantom, a metallic non magnetic element, which roughly simulates a medical implant.

Contactless Payment with RFID and NFC

2010 ◽  
pp. 112-120
Author(s):  
Marc Pasquet ◽  
Delphine Vacquez ◽  
Joan Reynaud ◽  
Félix Cuozzo
Keyword(s):  
Radio Frequency Identification ◽  
Information Integration ◽  
Short Distance ◽  
Near Field ◽  
Management Tools ◽  
Reading Technology ◽  
Frequency Identification ◽  
Set Up ◽  
The Cost ◽  
Contactless Card

The radio frequency identification (RFID) reading technology enables the transfer, by radio, of information from electronic circuit to a reader, opened up some interesting possibilities in the area of epayment (Domdouzis, Kumar, & Anumba, 2007). Today, the near field communication technology (NFC) opens up even more horizons, because it can be used to set up communications between different electronic devices (Eckert, 2005). Contactless cards, telephones with NFC capacities, RFID tag have been developed in industry and the services (Bendavid, Fosso Wamba, & Lefebvre, 2006). They are similar, but, some major differences explain the specificity of these three applications and the corresponding markets. The label, or marker, is a small size electronic element that transmits, on request, its numerical identification to a reader. The RFID identification makes it possible to store and recover data at short distance by using these miniature markers or labels (see Figure 1) associated to the articles to identify. The cost of the label is only few centimes. An RFID system is made of labels, readers connected to a fixed network, adapted software (collection of information, integration, confidentiality...), adapted services, and management tools that allow the identification of the products through packing. Contactless smartcards (see Figure 2) contain a microprocessor that can communicate under a short distance with a reader similar to those of RFID technology (Khu-smith & Mitchell, 2002). The originality of NFC is the fact that they were conceived for the protected bilateral transmission with other systems. NFC respects the standard ISO-14443 (Bashan, 2003) and thus, can be used as a contactless card. It can be used as a contactless terminal communicating with a contactless card or another NFC phone (ISO-18092). Services available through NFC are very limited today, but many experiments are in progress and electronic ticketing experiences (subways and bus) started in Japanb. There are two types of NFC phones: The mono chip composed of only one chip for GSM services (called the SIM) and NFC services. In that case, an NFC service is dependent of the phone operator. • The dual chip shows a clear separation of the two functions within two different chips. That completely isolates the operator and allows independent NFC services… We define the technology standards, the main platforms and actors in the background section. The main trust develops some contactless payment applications, and analyses the benefits and constraints of the different solutions. The future trends section concerns the research and technology evolution in contactless payment applications.

Contactless Payment with RFID and NFC

2011 ◽  
pp. 715-721
Author(s):  
Marc Pasquet ◽  
Delphine Vacquez ◽  
Joan Reynaud ◽  
Félix Cuozzo
Keyword(s):  
Radio Frequency Identification ◽  
Information Integration ◽  
Short Distance ◽  
Near Field ◽  
Management Tools ◽  
Reading Technology ◽  
Frequency Identification ◽  
Set Up ◽  
The Cost ◽  
Contactless Card

The radio frequency identification (RFID) reading technology enables the transfer, by radio, of information from electronic circuit to a reader, opened up some interesting possibilities in the area of e-payment (Domdouzis, Kumar, & Anumba, 2007). Today, the near field communication technology (NFC) opens up even more horizons, because it can be used to set up communications between different electronic devices (Eckert, 2005). Contactless cards, telephones with NFC capacities, RFID tag have been developed in industry and the services (Bendavid, Fosso Wamba, & Lefebvre, 2006). They are similar, but, some major differences explain the specificity of these three applications and the corresponding markets. The label, or marker, is a small size electronic element that transmits, on request, its numerical identification to a reader. The RFID identification makes it possible to store and recover data at short distance by using these miniature markers or labels (see Figure 1) associated to the articles to identify. The cost of the label is only few centimes. An RFID system is made of labels, readers connected to a fixed network, adapted software (collection of information, integration, confidentiality...), adapted services, and management tools that allow the identification of the products through packing. Contactless smartcards (see Figure 2) contain a microprocessor that can communicate under a short distance with a reader similar to those of RFID technology (Khu-smith & Mitchell, 2002). The originality of NFC is the fact that they were conceived for the protected bilateral transmission with other systems. NFC respects the standarda ISO-14443 (Bashan, 2003) and thus, can be used as a contactless card. It can be used as a contactless terminal communicating with a contactless card or another NFC phone (ISO-18092). Services available through NFC are very limited today, but many experiments are in progress and electronic ticketing experiences (subways and bus) started in Japan.

scholarly journals Formation and stability of 14C-containing organic compounds in alkaline iron-water systems: preliminary assessment based on a literature survey and thermodynamic modelling

2015 ◽  
Vol 79 (6) ◽  
pp. 1275-1286 ◽  
Author(s):  
E. Wieland ◽  
W. Hummel
Keyword(s):  
Radioactive Waste ◽  
Near Field ◽  
Water Systems ◽  
Thermodynamic Modelling ◽  
Preliminary Assessment ◽  
Carbon 14 ◽  
Current State ◽  
Alkaline Conditions ◽  
Anaerobic Corrosion ◽  
Intermediate Level Radioactive Waste

AbstractCarbon-14 is an important radionuclide in the inventory of radioactive waste and is considered to be a key radionuclide in performance assessment. In Switzerland, the 14C inventory in a cement-based repository for low- and intermediate-level radioactive waste is mainly associated with activated steel (∼85%). Anaerobic corrosion of the activated steel will determine the time-dependent release of 14C-bearing compounds from the cementitious near field into the host rock. The present study was carried out to provide an overview on the current state of the art knowledge regarding the carbon speciation during the anaerobic corrosion of activated and non-activated iron/steel and to critically assess the capability of thermodynamic modelling to predict 14C speciation in anoxic alkaline conditions. Previous experimental work showed the presence of oxidized and reduced hydrocarbons during corrosion in iron-water systems in anoxic (near neutral to alkaline) conditions which appears to be inconsistent with the negative redox potential of the system. The capability of thermodynamic modelling to predict the carbon speciation in these conditions was found to be limited due to uncertainties associated with the concept of metastability in the C–H–O system.

Impingement of a propeller-slipstream on a leading edge with a flow-permeable insert: A computational aeroacoustic study

2018 ◽  
Vol 17 (6-8) ◽  
pp. 687-711 ◽  
Author(s):  
Francesco Avallone ◽  
Damiano Casalino ◽  
Daniele Ragni
Keyword(s):  
Computational Study ◽  
Near Field ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Broadband Noise ◽  
Blade Passage ◽  
Propeller Wake ◽  
Upstream Direction ◽  
Field Noise ◽  
Set Up

This manuscript describes an aeroacoustic computational study on the impingement of a tractor-propeller slipstream on the leading edge of a pylon. Both the flow and acoustic fields are studied for two pylon leading edges: a solid and a flow-permeable one. The computational set-up replicates experiments performed at Delft University of Technology. Computational results are validated against measurements. It is found that the installation of the flow-permeable leading-edge insert generates a thicker boundary layer on the retreating blade side of the pylon. This is caused by an aerodynamic asymmetry induced by the helicoidal motion of the propeller wake, which promotes a flow motion through the cavity from the advancing to the retreating blade side of the pylon. The flow-permeable leading-edge insert mitigates the amplitude of the surface pressure fluctuations only on the pylon-retreating blade side towards the trailing edge, thus reducing structure-borne noise. Furthermore, it causes a reduction of the near-field noise only for receiver angles oriented in the upstream direction at the pylon-retreating blade side. In this range of receiver angles, it is found that the flow-permeable leading-edge insert reduces the amplitude of the tonal peaks for the third and fourth blade passage frequency, but strongly increases the broadband noise for frequencies higher that the seventh blade passage frequency.

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