37 research outputs found
Caracterización microestructural de recubrimientos NiCoCrAlYTa obtenidos por láser coaxial y por refusión láser sobre AISI 316L
[ES] En este estudio se ha evaluado la microestructura de recubrimientos NiCoCrAlYTa depositados
mediante la técnica de laser cladding coaxial, y en recubrimientos obtenidos por proyección
térmica de alta velocidad (HVOF) y refundidos por láser, ambos sobre láminas de acero
inoxidable AISI 316L. Se ha analizado la microestructura, variaciĂłn de microdureza y
composiciĂłn quĂmica, mediante microscopĂa Ăłptica, microscopĂa electrĂłnica de barrido (MEB) y
microanálisis por espectroscopĂa de energĂa dispersiva (EDS). Los recubrimientos obtenidos no
presentan macro defectos importantes y existe una buena uniĂłn metalĂşrgica con el sustrato; no
obstante, existe una estructura dendrĂtica columnar no homogĂ©nea que depende del procesado
láser. Los análisis evidencian la disoluciĂłn y mezcla de elementos quĂmicos relevantes con el NiCr
que generan una variaciĂłn gradual entre sustrato y recubrimiento que influye en el
endurecimiento observado en la intercara del recubrimiento. Se logra la densificaciĂłn de los
recubrimientos HVOF eliminando la porosidad inicial y mejorando su acabado superficial,
diferencias en la disoluciĂłn de elementos quĂmicos han sido encontradas para las dos tĂ©cnicas
utilizadas, debido al espesor del recubrimiento obtenido y los parámetros láser utilizados.[EN] In this study the microstructure of NiCoCrAlYTa coatings deposited by coaxial laser cladding
technique, and laser remelted coatings obtained previously by high velocity oxy fuel thermal
spraying (HVOF), both on sheets of stainless steel AISI 316L, were evaluated. Optical
microscopy, scanning electron microscopy, and energy dispersive spectroscopy microanalysis
have been used to analyze the chemical composition, microstructure, and microhardness. A
coatings without cracks or macro pores and a good metallurgical bond with the substrate through
the dilution zone was obtained; yet there is no a homogeneous columnar dendrite structure that
depends of laser processing parameters. The analysis evidenced the dilution and mixing of
relevant chemical elements such as Fe, Co, Al and Ta with Ni-Cr, generating a gradual variation
between substrate and coating which influence the hardening observed at the interface of the
coating. The densification is achieved by removing HVOF coating initial porosity and improving
the surface finish, differences in the chemicals components dissolution have been found for the
two techniques employed, influence by the thickness coating and by the laser parameters.Pereira Falcón, JC.; Candel Bou, JJ.; Amado, J.; Amigó Borrás, V. (2014). Caracterización microestructural de recubrimientos NiCoCrAlYTa obtenidos por láser coaxial y por refusión láser sobre AISI 316L. Revista Colombiana de Materiales. Especial(5):127-132. http://hdl.handle.net/10251/91890S127132Especial
Mixing Bandt-Pompe and Lempel-Ziv approaches: another way to analyze the complexity of continuous-states sequences
In this paper, we propose to mix the approach underlying Bandt-Pompe
permutation entropy with Lempel-Ziv complexity, to design what we call
Lempel-Ziv permutation complexity. The principle consists of two steps: (i)
transformation of a continuous-state series that is intrinsically multivariate
or arises from embedding into a sequence of permutation vectors, where the
components are the positions of the components of the initial vector when
re-arranged; (ii) performing the Lempel-Ziv complexity for this series of
`symbols', as part of a discrete finite-size alphabet. On the one hand, the
permutation entropy of Bandt-Pompe aims at the study of the entropy of such a
sequence; i.e., the entropy of patterns in a sequence (e.g., local increases or
decreases). On the other hand, the Lempel-Ziv complexity of a discrete-state
sequence aims at the study of the temporal organization of the symbols (i.e.,
the rate of compressibility of the sequence). Thus, the Lempel-Ziv permutation
complexity aims to take advantage of both of these methods. The potential from
such a combined approach - of a permutation procedure and a complexity analysis
- is evaluated through the illustration of some simulated data and some real
data. In both cases, we compare the individual approaches and the combined
approach.Comment: 30 pages, 4 figure
Trends in arsenic levels in PM10 and PM2.5 aerosol fractions in an industrialized area
Arsenic is a toxic element that affects human health and is widely distributed in the environment. In the area of study, the main Spanish and second largest European industrial ceramic cluster, the main source of arsenic aerosol is related to the impurities in some boracic minerals used in the ceramic process. Epidemiological studies on cancer occurrence in Spain points out the study region as one with the greater risk of cancer. Concentrations of particulate matter and arsenic content in PM10 and PM2.5 were measured and characterized by ICP-MS in the area of study during the years 2005-2010. Concentrations of PM10 and its arsenic content range from 27 to 46 mu g/m(3) and from 0.7 to 6 ng/m(3) in the industrial area, respectively, and from 25 to 40 mu g/m(3) and from 0.7 to 2.8 ng/m(3) in the urban area, respectively. Concentrations of PM2.5 and its arsenic content range from 12 to 14 mu g/m(3) and from 0.5 to 1.4 ng/m(3) in the urban background area, respectively. Most of the arsenic content is present in the fine fraction, with ratios of PM2.5/PM10 in the range of 0.65-0.87. PM10, PM2.5, and its arsenic content show a sharp decrease in recent years associated with the economic downturn, which severely hit the production of ceramic materials in the area under study. The sharp production decrease due to the economic crisis combined with several technological improvements in recent years such as substitution of boron, which contains As impurities as raw material, have reduced the concentrations of PM10, PM2.5, and As in air to an extent that currently meets the existing European regulations.The authors are grateful to Ilmo. Ayuntamiento de L'Alcora for the financial support through the 07I055 project, Generalitat Valenciana for their support and collaboration, and Miss Miriam Rubio Renau for her assistance in the laboratory work. Also, the authors are indebted to an anonymous referee for the interesting suggestions.GarcĂa Aleix, J.; Delgado Saborit, J.; VerdĂş MartĂn, GJ.; AmigĂł Descarrega, JM.; Esteve Cano, V. (2014). Trends in arsenic levels in PM10 and PM2.5 aerosol fractions in an industrialized area. Environmental Science and Pollution Research. 21(1):695-703. https://doi.org/10.1007/s11356-013-1950-0S695703211Arruti A, Fernandez-Olmo I, Irabien A (2011) Impact of the global economic crisis on metal levels in particulate matter (PM) at an urban area in the Cantabria region (northern Spain). Environ Pollut 159:1129–1135Arslan F, Arslan C, Celik MS (1999) Arsenic removal through the decrepitation of colemanite ores. Powder Technol 103:260–264Benach J, Yasui Y, Borrell C, Rosa E, Pasarin MI, Benach N et al (2003) Examining geographic patterns of mortality: the atlas of mortality in small areas in Spain (1987–1995). Eur J Public Health 13:115–123Cantor KP, Lubin JH (2007) Arsenic, internal cancers, and issues in inference from studies of low-level exposures in human populations. Toxicol Appl Pharmacol 222:252–257Celades I, Moliner-Salvador R, Ros-Dosda T, Monfort E, Zaera V (2012) Environmental development of the spanish ceramic tile manufacturing sector over the period 1992–2007. Boletin de la Sociedad Espanola de Ceramica y Vidrio 51:111–118Chappell WR, Abernathy CO, Calderon RL, Thomas DJ (eds) (2003) Arsenic exposure and health effects V. Proceedings of the Fifth International Conference on Arsenic Exposure and Health Effects, 14–18 July 2002, San Diego, CaliforniaChen WH, Bochmann F, Sun Y (2007) Effects of work related confounders on the association between silica exposure and lung cancer: a nested case–control study among Chinese miners and pottery workers. Int Arch Occup Environ health 80:320–326CNE (Centro Nacional de EpidemiologĂa) (2011) Available at http://revista.isciii.es/index.php/bes/article/view/339Cohen SM, Arnold LL, Eldan M, Lewis AS, Beck BD (2006) Methylated arsenicals: the implications of metabolism and carcinogenicity studies in rodents to human risk assessment. Crit Rev Toxicol 36:99–133Delgado-Saborit JM, Esteve-Cano V (2007) Field comparison of passive samplers versus UV-photometric analyser to measure surface ozone in a Mediterranean area. J Environ Monit 9:610–615Diaz-Villasenor A, Burns AL, Hiriart M, Cebrian ME, Ostrosky-Wegman P (2007) Arsenic-induced alteration in the expression of genes related to type 2 diabetes mellitus. Toxicol Appl Pharmacol 225:123–133Directive 1999/30/EC of the European Parliament and of the Council of 22 April 1999 relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient airDirective 2004/107/EC of the European Parliament and of the Council of 15 December 2004 relating to arsenic, cadmium, mercury, nickel and polycyclic aromatic hydrocarbons in ambient airDuker AA, Carranza EJM, Hale M (2005) Arsenic geochemistry and health. Environ Int 31:631–641Englyst V, Lundstrom NG, Gerhardsson L, Rylander L, Nordberg G (2001) Lung cancer risks among lead smelter workers also exposed to arsenic. Sci Total Environ 273:77–82Esteve V, Peris G (2000) Ionic characterization of size fractionated airborne tropospheric particulate at CastellĂłn (Spain). Journal of Aerosol Science 31:346–347Esteve V, Ramos A (1999) Materiales para la decoraciĂłn cerámica. Recomendaciones para su correcta manipulaciĂłnFang GC, Chang CN, Wu YS, Fu PPC, Yang DG, Chu CC (1999) Characterization of chemical species in PM2.5 and PM10 aerosols in suburban and rural sites of central Taiwan. Sci Total Environ 234:203–212Fernandez-Camacho R, Rodriguez S, de la Rosa J, de la Campa AMS, Viana M, Alastuey A et al (2010) Ultrafine particle formation in the inland sea breeze airflow in southwest Europe. Atmos Chem Phys 10:9615–9630Figueroa DA, Rodriguez-Sierra CJ, Jimenez-Velez BD (2006) Concentrations of Ni and V, other heavy metals, arsenic, elemental and organic carbon in atmospheric fine particles (PM2.5) from Puerto Rico. Toxicol Ind Health 22:87–99Gao Y, Nelson ED, Field MP, Ding Q, Li H, Sherrell RM, Gigliotti CL, Van Ry DA, Glenn TR, Eisenreich SJ (2002) Characterization of atmospheric trace elements on PM(2.5) particulate matter over the New York–New Jersey harbor estuary. Atmos Environ 36:1077–1086Halek F, Keyanpour-Rad M, Darbani RM, Kavousirahim A (2010) Concentrations and source assessment of some atmospheric trace elements in northwestern region of Tehran, Iran. Bull Environ Contam Toxicol 84:185–190Hayes RB (1997) The carcinogenicity of metals in humans. Cancer Causes Control 8:371–385He ZLL, Yang XE, Stoffella PJ (2005) Trace elements in agroecosystems and impacts on the environment. J Trace Elem Med Biol 19:125–140Hetland RB, Refsnes M, Myran T, Johansen BV, Uthus N, Schwarze PE (2000) Mineral and/or metal content as critical determinants of particle-induced release of IL-6 and IL-8 from A549 cells. J Toxicol Environ Health A 60:47–65Ho KF, Lee SC, Yu JC, Zou SC, Fung K (2002) Carbonaceous characteristics of atmospheric particulate matter in Hong Kong. Sci Total Environ 300:59–67Holmes CW, Miller R (2004) Atmospherically transported elements and deposition in the southeastern United States: local or transoceanic? Appl Geochem 19:1189–1200IARC (2009) IARC monographs on the evaluation of carcinogenic risks to humans. Complete list of agents evaluated and their classification. IARC Monograph 100C-6 2012. Available at http://monographs.iarc.fr/ENG/Classification/index.phpJomova K, Jenisova Z, Feszterova M, Baros S, Liska J, Hudecova D et al (2011) Arsenic: toxicity, oxidative stress and human disease. J Appl Toxicol 31:95–107Karagolge Z, Alkan M, Donmez B (2002) Removal of arsenic from colemanite ore containing arsenic by froth flotation. J Chem Eng Jpn 35:217–225Lewis AS, Reid KR, Pollock MC, Campleman SL (2012) Speciated arsenic in air: measurement methodology and risk assessment considerations. J Air Waste Manage Assoc 62:2–17Mandal BK, Suzuki KT (2002) Arsenic round the world: a review. Talanta 58:201–235Marcazzan GM, Vaccaro S, Valli G, Vecchi R (2001) Characterisation of PM10 and PM2.5 particulate matter in the ambient air of Milan (Italy). Atmos Environ 35:4639–4650Millán MM, Salvador R, Mantilla E (1997) Photooxidant dynamics in the Mediterranean basin in summer: results from European research projects. J Geophys Res 102(D7):8811–8823Minguillon MC, Monfort E, Querol X, Alastuey A, Celades I, Miro JV (2009) Effect of ceramic industrial particulate emission control on key components of ambient PM(10). J Environ Manage 90:2558–2567Navas-Acien A, Sharrett AR, Silbergeld EK, Schwartz BS, Nachman KE, Burke TA et al (2005) Arsenic exposure and cardiovascular disease: a systematic review of the epidemiologic evidence. Am J Epidemiol 162:1037–1049Pacyna EG, Pacyna JM, Fudala J, Strzelecka-Jastrzab E, Hlawiczka S, Panasiuk D et al (2007) Current and future emissions of selected heavy metals to the atmosphere from anthropogenic sources in Europe. Atmos Environ 41:8557–8566Pallares S, Vicente AB, Jordan MM, Sanfeliu T (2007) Study of the levels of concentration of As, Cd and Ni in a ceramic cluster. Water Air Soil Pollut 180:51–64Putaud JP, Raes F, Van Dingenen R, Bruggemann E, Facchini MC, Decesari S et al (2004) European aerosol phenomenology—2: chemical characteristics of particulate matter at kerbside, urban, rural and background sites in Europe. Atmos Environ 38:2579–2595Querol-Balaguer MA, Delgado-Saborit JM, Ramos-Pino F, AmigĂł-Descarrega JM, Esteve-Cano V (2004) Chemical characterization of PM10 airborne particulate matter at the ceramic cluster of Castellon (Spain). Geophys Res Lett 6:6108Querol X, Alastuey A, Moreno T, Viana MM, Castillo S, Pey J et al (2008) Spatial and temporal variations in airborne particulate matter (PM10 and PM2.5) across Spain 1999–2005. Atmos Environ 42:3964–3979Querol X, Alastuey A, Rodriguez S, Plana F, Mantilla E, Ruiz CR (2001) Monitoring of PM10 and PM2.5 around primary particulate anthropogenic emission sources. Atmos Environ 35:845–858Querol X, Alastuey A, Rodriguez S, Viana MM, Artinano B, Salvador P et al (2004a) Levels of particulate matter in rural, urban and industrial sites in Spain. Sci Total Environ 334:359–376Querol X, Alastuey A, Ruiz CR, Artinano B, Hansson HC, Harrison RM et al (2004b) Speciation and origin of PM10 and PM2.5 in selected European cities. Atmos Environ 38:6547–6555Querol X, Minguillon MC, Alastuey A, Monfort E, Mantilla E, Sanz MJ et al (2007) Impact of the implementation of PM abatement technology on the ambient air levels of metals in a highly industrialised area. Atmos Environ 41:1026–1040Rampazzo G, Masiol M, Visin F, Rampado E, Pavoni B (2008) Geochemical characterization of PM10 emitted by glass factories in Murano, Venice (Italy). Chemosphere 71:2068–2075Roy P, Saha A (2002) Metabolism and toxicity of arsenic: a human carcinogen. Curr Sci 82:38–45Sanchez-Rodas D, Sanchez de la Campa A, Oliveira V, de la Rosa J (2012) Health implications of the distribution of arsenic species in airborne particulate matter. J Inorg Biochem 108:112–114Sanchez de la Campa AM, de la Rosa J, Gonzalez-Castanedo Y, Fernandez-Camacho R, Alastuey A, Querol X et al (2011) Levels and chemical composition of pm in a city near a large Cu-smelter in Spain. J Environ Monit 13:1276–1287Sanchez de la Campa AM, de la Rosa JD, Sanchez-Rodas D, Oliveira V, Alastuey A, Querol X et al (2008) Arsenic speciation study of PM2.5 in an urban area near a copper smelter. Atmos Environ 42:6487–6495Santacatalina M, Yubero E, Mantilla E, Carratlá A (2011) Relevance of the economic crisis in chemical PM10 changes in a semi-arid industrial environment. Environ Monit Assess 184:6827–6844Tsopelas F, Tsakanika L-A, Ochsenkuehn-Petropoulou M (2008) Extraction of arsenic species from airborne particulate filters—application to an industrial area of Greece. Microchem J 89:165–170Vahidnia A, Van der Voet GB, de Wolf FA (2007) Arsenic neurotoxicity—a review. Hum Exp Toxicol 26:823–832Vickery W, Moreno A, Monfort E (1998) Influencia de las materias primas borácicas en las emisiones de los hornos de fusiĂłn de fritas. Qualicer 98:205–214von Schneidemesser E, Stone EA, Quraishi TA, Shafer MM, Schauer JJ (2010) Toxic metals in the atmosphere in Lahore, Pakistan. Sci Total Environ 408:1640–1648WHO (2000) Air quality guidelines for Europe. WHO Regional Office for Europe Copenhage
Laser Cladding of MCrAlY coatings on stainless steel
MCrAlY alloys (where M stands for Ni,Co or both) are commonly used as overlay protective coatings in gas turbine engine components against high temperature oxidation and corrosion. The protective effect of these alloys is due to the formation of a continuous thermally stable oxide layer on the coating surface. In this work several types of MCrAlY alloys, differing in their elemental composition, have been deposited on austenitic stainless steel by means of laser cladding. The microstructure of the coatings have been characterized by SEM-EDS and XRD. As expected, elemental composition compatible with γ-Ni/γ'-Ni3Al, β-Ni/β'-NiAl or γCo/β-(Co,Ni)Al phases are observed in hypoeutectic or hypereutectic microstructures depending on the alloy composition. The high temperature oxidation behavior of the coatings was evaluated by air furnace oxidation tests at 1100ÂşC for 200 h. The oxidized surface of the samples was examined by SEM-EDS and the oxides present identified by theoretical stoichiometric calculations. Results indicate the formation of a uniform Al3O2 protective oxide scale with NiO, CoO, Y2O3/YAlO3 and Cr2O3 oxide inclusions.Tobar, M.; Amado, J.; Yáñez, A.; Pereira FalcĂłn, JC.; AmigĂł Borrás, V. (2014). Laser Cladding of MCrAlY coatings on stainless steel. Physics Procedia. 56(C):276-283. doi:10.1016/j.phpro.2014.08.172S27628356
Crack Free Tungsten Carbide Reinforced Ni(Cr) Layers obtained by Laser Cladding
[EN] The development of hardfacing coatings has become technologically significant in many industries A common approach is the production of metal matrix composites (MMC) layers. In this work NiCr-WC MMC hardfacing layers are deposited on C25 steel by means of laser cladding. Spheroidal fused tungsten carbides is used as reinforcement phase. Three different NiCr alloys with different Cr content were tested. Optimum conditions to obtain dense, uniform carbide distribution and hardness close to nominal values were defined. The effect of Cr content respect to the microstructure, susceptibility for cracking and the wear rate of the resulting coating will also be discussed. © 2011 Published by Elsevier Ltd.This works has been done under the financial support of Xunta de Galicia, project reference 08DPI024CT, Programa de Diseno y Produccion Industrial.Amado Paz, JM.; Tobar Vidal, MJ.; Yañez Casal, AJ.; Amigó Borrás, V.; Candel Bou, JJ. (2011). Crack Free Tungsten Carbide Reinforced Ni(Cr) Layers obtained by Laser Cladding. Physics Procedia. 12(1):338-344. https://doi.org/10.1016/j.phpro.2011.03.043S33834412
Dynamical complexity of short and noisy time series: Compression-Complexity vs. Shannon entropy
Shannon entropy has been extensively used for characteriz-
ing complexity of time series arising from chaotic dynamical systems and stochastic processes such as Markov chains. However, for short and noisy time series, Shannon entropy performs poorly. Complexity measures which are based on lossless compression algorithms are a good substitute in such scenarios. We evaluate the performance of
two such Compression-Complexity Measures namely Lempel-Ziv complexity(LZ)andEffort-To-Compress(
ETC)onshorttimeseriesfrom chaoticdynamicalsystemsinthepresenceofnoise.Both
LZ and ETC outperform Shannon entropy (H) in accurately characterizing the dynamical complexity of such systems. For very short binary sequences
(which arise in neuroscience applications),
ETC has higher number of distinct complexity values than
LZ and H, thus enabling a finer resolution. For two-state ergodic Markov chains, we empirically show that ETC
converges to a steady state value faster than LZ.
Compression-Complexity measures
are promising for applications which involve short
and noisy time series
Permutation entropy: One concept, two approaches
Since C. Bandt and B. Pompe introduced permutation entropy in 2002 for piecewise strictly monotonous self-maps of one-dimensional intervals, this concept has been generalized to ever more general settings by means of two similar, though not equivalent, approaches. The first one keeps the original spirit in that it uses “sharp” dynamics and the corresponding ordinal partitions. The second uses symbolic (or “coarse-grained” dynamics with respect to arbitrary finite partitions, as in the conventional approach to the Kolmogorov-Sinai entropy of dynamical systems. Precisely, one of the main questions along these two avenues refers to the relation between permutation entropy and Kolmogorov-Sinai entropy. In this paper the authors will explain the underpinnings of both approaches and the latest theoretical results on permutation entropy. The authors also discuss some remaining open questions