Optical analysis of blast furnace gas combustion in a laboratory premixed burner

The use of blast furnace gas (BFG) as a fuel provides an alternative for waste stream valorization in the steel industry, enhancing the sustainability and decarbonization of its processes. Nevertheless, the implementation of this solution on an industrial scale requires a continuous control of the combustion due to the low calorific value of BFG. This work analyzes the combustion behavior and monitoring of BFG/CH4blends in a laboratory premixed fuel burner. We evaluate several stable combustion conditions by burning different BFG/CH4mixtures at a constant power rate over a wide range of air/fuel equivalence ratios. In addition, relevant image features and chemiluminescence emission spectra have been extracted from flames, using advanced optical devices. BFG combustion causes an increase in CO2and CO emissions, since those fuels are the main fuel components of the mixture. On the other hand, NOxemissions decreased because of the low temperature of combustion of the BFG and its mixtures. Chemiluminescence shows that, in the case of CH4combustion, peaks associated with hydrocarbons are present, while during the substitution of CH4by BFG those peaks are attenuated. Image flame features extracted from both ultraviolet and visible bandwidths show a correlation with the fuel blend and air/fuel equivalence ratio. In the end, methodologies developed in this work have been proven to be valuable alternatives with a high potential for the monitoring and control of BFG cofiring for the steel industry

Magnetic phase separation in ordered alloys

We present a lattice model to study the equilibrium phase diagram of ordered alloys with one magnetic component that exhibits a low temperature phase separation between paramagnetic and ferromagnetic phases. The model is constructed from the experimental facts observed in Cu$_{3-x}$AlMn$_{x}$ and it includes coupling between configurational and magnetic degrees of freedom which are appropriated for reproducing the low temperature miscibility gap. The essential ingredient for the occurrence of such a coexistence region is the development of ferromagnetic order induced by the long-range atomic order of the magnetic component. A comparative study of both mean-field and Monte Carlo solutions is presented. Moreover, the model may enable the study of the structure of the ferromagnetic domains embedded in the non-magnetic matrix. This is relevant in relation to phenomena such as magnetoresistance and paramagnetism.Comment: 12 pages, 11 figures, accepted in Phys. Rev.

Deceleration area and fetal acidemia

Aims: To compare the predictive ability for neonatal acidemia of individual components of intrapartum cardiotocography (CTG) described by National Institute of Child Health and Human Development (NICHD) system and deceleration area. Design: Case-control study. Setting: Spanish tertiary obstetrical hospital. Population: CTG patterns of 102 acidemic fetus (umbilical arterial cord gas pH =7.10, base deficit (BD>48) and 102 nonacidemic controls (umbilical arterial cord gas pH>7.10). Methods: Two reviewers blind to clinical and outcome data analyzed the last thirty minutes before delivery of 204 fetal heart rate (FHR) tracings, extracting those features defined by NICHD and certain measures of FHR decelerations, including deceleration area, not considered by this system. Outcome measures: The primary outcome was the predictive ability of NICHD features and non-NICHD deceleration measures for fetal acidemia. The secondary outcome was the impact of deceleration area in the last 30 min of labor on gasometry components (pH, BD and lactate). Results: Minimal variability (area under the curve (AUC) 0.74), total number of late (AUC: 0.75) and prolonged decelerations (0.77) were the three NICHD features with the greatest predictive ability for fetal acidemia in the last thirty minutes of labor. Total deceleration area demonstrated the highest discrimination power (AUC: 0.83) of all the analyzed elements. For each cm2 the area increases in the last 30 min of labor, pH decreases 0.08 units, BD increases 0.272 mEq/L and lactate 0.183 mEq/L. Conclusions: Total deceleration area showed the greatest predictive ability for fetal acidemia and its measure could help to estimate intrapartum fetal acid-base status

Impact of mobile emergency units on survival of acute myocardial infarction

Objetivo: Demostrar que los pacientes con infarto Agudo de miocardio(IAM) atendidos por una unidad móvil de emergencia (UME) tienen menos complicaciones y menor gravedad que los pacientes que acuden al hospital en ambulancia convencional.Objective: To demonstrate that patients with acute myocardial infarction (AMI) treated by a mobile emergency unit (EMU) have fewer complications and less severity than patients who go to the hospital by conventional ambulance

Subaltern forms of knowledge are required to boost local adaptation

Evidence shows that current adaptation planning approaches are not always successful in generating actionable knowledge to guide implementation on the ground. There remains a persistent disconnect between the production of (physical) climate science and the implementation of practical, local, and context-specific adaptation actions. We argue for a need to incorporate “subaltern” knowledge (i.e., that which is typically labeled local, traditional, or indigenous knowledge) in climate adaptation science and practice. Building on recent comparative assessment studies, we identify limitations of current local adaptation action in its typical application of scientific knowledge and illustrate key pathways through which the subaltern can be integrated to better inform current approaches. We argue that subaltern knowledge can be a critical source of innovation and can help to broaden the adaptation solution space by enhancing both the effectiveness and the social legitimacy of actions

Magnetic stress as a driving force of structural distortions: the case of CrN

We show that the observed transition from rocksalt to orthorhombic P$_{nma}$ symmetry in CrN can be understood in terms of stress anisotropy. Using local spin density functional theory, we find that the imbalance between stress stored in spin-paired and spin-unpaired Cr nearest neighbors causes the rocksalt structure to be unstable against distortions and justifies the observed antiferromagnetic ordering. This stress has a purely magnetic origin, and may be important in any system where the coupling between spin ordering and structure is strong.Comment: 4 pages (two columns) 4 figure

Electrical characterization of atomic-layer-deposited hafnium oxide films from hafnium tetrakis(dimethylamide) and water/ozone: Effects of growth temperature, oxygen source, and postdeposition annealing

The electrical properties of HfO2-based metal-insulator- semiconductor capacitors have been systematically investigated by means of I-V and C-V characteristics, admittance spectroscopy, deep level transient spectroscopy, conductance transient, and flat band voltage transient techniques. Attention is also given to the study of the temperature dependence of the leakage current. HfO2 films were grown on p-type silicon substrates by atomic layer deposition using hafnium tetrakis(dimethylamide) as hafnium precursor, and ozone or water as oxygen precursors. The growth temperature ranged from 150 to 350 °C. Low growth temperatures prevent decomposition and high growth rate, as well as high contamination levels. As a result, the leakage current is lower for lower deposition temperatures. Some of the deposited samples were submitted to a postdeposition annealing at 650 °C in N2 atmosphere, showing a decrease in the leakage current and an increase in the equivalent oxide thickness (EOT), whereas interfacial state density increases and defect density inside the dielectric bulk decreases. Regarding dielectric reliability, in our experimental conditions, HfO 2 layers grown at 150 °C exhibit the largest EOT and breakdown voltage. The electrical behaviour is clearly linked with structural properties, and especially with the formation of an interfacial layer between the HfO 2 layer and the silicon substrate, as well as with the presence of several impurities. © 2013 American Vacuum Society.Peer Reviewe

Magnetic properties of Ni2.18Mn0.82Ga Heusler alloys with a coupled magnetostructural transition

Polycrystalline Ni2.18Mn0.82Ga Heusler alloys with a coupled magnetostructural transition are studied by differential scanning calorimetry, magnetic and resistivity measurements. Coupling of the magnetic and structural subsystems results in unusual magnetic features of the alloy. These uncommon magnetic properties of Ni2.18Mn0.82Ga are attributed to the first-order structural transition from a tetragonal ferromagnetic to a cubic paramagnetic phase.Comment: 4 pages, 4 figures, revtex

Vacancy-assisted domain-growth in asymmetric binary alloys: a Monte Carlo study

A Monte Carlo simulation study of the vacancy-assisted domain-growth in asymmetric binary alloys is presented. The system is modeled using a three-state ABV Hamiltonian which includes an asymmetry term, not considered in previous works. Our simulated system is a stoichiometric two-dimensional binary alloy with a single vacancy which evolves according to the vacancy-atom exchange mechanism. We obtain that, compared to the symmetric case, the ordering process slows down dramatically. Concerning the asymptotic behavior it is algebraic and characterized by the Allen-Cahn growth exponent x=1/2. The late stages of the evolution are preceded by a transient regime strongly affected by both the temperature and the degree of asymmetry of the alloy. The results are discussed and compared to those obtained for the symmetric case.Comment: 21 pages, 9 figures, accepted for publication in Phys. Rev.

2D magnetic domain wall ratchet: The limit of submicrometric holes

The study of ratchet and crossed-ratchet effects in magnetic domain wall motion through 2D arrays of asymmetric holes is extended in this article to the submicrometric limit in hole size (small size regime). Therefore, the gap has been closed between the 2D ratchets in the range of tens-of-micrometers (large size regime) and the small size regime 1D ratchets based on nanowires. The combination of Kerr microscopy, X-ray PhotoEmission Electron Microscopy and micromagnetic simulations has allowed a full magnetic characterisation of both the domain wall (DW) propagation process over the whole array and the local DW morphology and pinning at the holes. It is found that the 2D small size limit is driven by the interplay between DW elasticity and half vortex propagation along hole edges: as hole size becomes comparable to DW width, flat DW propagation modes are favoured over kinked DW propagation due to an enhancement of DW stiffness, and pinned DW segments adopt asymmetric configurations related with Néel DW chirality. Nevertheless, both ratchet and crossed-ratchet effects have been experimentally found, and we propose a new ratchet/inverted-ratchet effect in the submicrometric range driven by magnetic fields and electrical currents respectively