2,653 research outputs found
From Late Prehistory to the Foundation of Early States in Inland Southeast Asia: a Debate
Mortuary data from three Iron Age sites in Northeast Thailand and three in Northwest Cambodia are here reviewed for information on social formation on the cusp of early states. It has been suggested that the three Cambodian sites present evidence for a complex polity with three social tiers and that this contrasts with the lack of any evidence for equivalent complexity in the three communities in the upper Mun Valley of Northeast Thailand. This model is examined and queried on the basis of insufficient data for the Cambodian sites, and contestable statistical analysis. In its place, an alternative is presented, that identifies a critically important climatic deterioration causing increased aridity which stimulated the development of plough-based wet rice cultivation in irrigated permanent fields. In the upper Mun Valley of Northeast Thailand, this coincided with a swift rise in social elites, interred in lineage-based nuclei in which leading individuals were accompanied by unprecedented wealth. Within a century or two, some Iron Age settlements greatly expanded into regal centers documented through texts that mentioned the state of Sri Canasapura. This transition might also have occurred in Northwest Cambodia at the same time, but evidence for this is so far unconvincing
Medición de esfuerzos residuales mediante la técnica de replicación de indentaciones en monobloques V8 de aluminio.
El presente trabajo de investigación presenta la Técnica de Replicación de Indentaciones para la medición de esfuerzos residuales en los puentes entre cilindros en siete monobloques V8 de aluminio. Esta técnica mide el cambio en el espaciamiento entre pares de huellas antes y después de un relevado de esfuerzos, relacionando esta deformación mediante la ley de Hooke con los esfuerzos residuales, empleando el Sistema de Replicación de Indentaciones para transferir la superficie de los puentes entre cilindros en réplicas positivas, precisas y estables, con una variación de ≈+2 μm respecto a las mediciones directas del espaciamiento entre pares de huellas, ofreciendo resultados precisos y adecuados para numerosas aplicaciones por su versatilidad, almacenamiento y transportación de las réplicas, para la medición de esfuerzos residuales.
La Técnica de Replicación de Indentaciones al igual que la Técnica de Galgas Extensométricas Uniaxiales para la medición de la deformación en los puentes entre cilindro, revelaron que los esfuerzos residuales estaban sometidos a tensión, donde la dirección del máxima esfuerzo es tangencial a las camisas de hierro gris.
El mapeo de esfuerzos residuales reflejó campos de esfuerzos a lo largo de los puentes entre cilindros, los cuales se asocian a factores geométricos vinculados al cambio de espesor, aumentando considerablemente la magnitud de los esfuerzos residuales al disminuir el espesor debido a la distribución de la carga en un área menor, concentrándose el máximo esfuerzo al centro de los puentes entre cilindros. El procesamiento de datos y los análisis estadísticos de la evaluación de esfuerzos residuales al centro de los puentes entre cilindros mediante la Técnica de Replicación de Indentaciones y la Técnica de Galgas Extensométricas fue estadísticamente significativa con un nivel de confianza del 95.0% (α=0.05)
Estudio del comportamiento a fatiga a bajo ciclo de las aleaciones de aluminio hipoeutécticas
Este trabajo de investigación presenta la caracterización de las propiedades mecánicas estáticas y dinámicas, así como del efecto Bauschinger de las aleaciones hipoeutécticas A319 T7, A356 T6 y A356+0.5Cu T6. Lo cual, permitió establecer, como
aportación científica, nuevas teorías sobre el comportamiento de los mecanismos de endurecimiento, en el campo plástico, como la mutua determinación de los parámetros microestructurales y de las propiedades mecánicas de dichas aleaciones y, a su vez, con los parámetros del proceso de fundición, y viceversa. Que, a su vez, por distinción analógica, permitió hacer predicciones e inferencias con mayor precisión sobre el comportamiento a fatiga a bajo ciclo de componentes automotrices, como, por ejemplo, la cabeza de cilindros, siendo esta la aportación tecnológica del estudio. De tal manera que, dichas aleaciones presentaron un modelo de endurecimiento cinemático a isotrópico, es decir, presentaron un ablandamiento permanente, en el primer ciclo de histéresis, pasando por un endurecimiento cíclico estable, en tanto que cercano a la fractura por
fatiga, presentaron un ablandamiento cíclico.
A través de la fractografía, se determinó que los defectos inherentes al proceso de vaciado, como, por ejemplo, la porosidad cercana a la superficie y de mayor tamaño, dominaron el fenómeno de nucleación; se observó también estrías por fatiga, así como partículas dañadas, agrietadas y desprendidas. Por otra parte, el fenómeno de propagación de la grieta, devino por la coalescencia de microgrietas, a través de regiones con mayor densidad de defectos y partículas quebradizas, hasta crecer a grietas de tamaño macroscópico y, por último, presentando un modo de fractura dúctil de coalescencia, es
decir, la unión e interacción entre microporos, aceleró la fractura. Lo cual, permitió demostrar que la naturaleza de las partículas de mayor presencia, en el primer ciclo de histéresis, determinó el comportamiento del efecto Bauschinger de las aleaciones A319 T7, A356 T6 y A356+0.5Cu T6, disminuyendo dicho fenómeno a medida que aumentó la deformación plástica y, a su vez, ajustándose a un comportamiento tipo Masing.
Abstract
This research work presents the characterization of the static and dynamic mechanical properties, as well as the Bauschinger effect of the hypoeutectic alloys A319 T7, A356 T6 and A356+0.5Cu T6. This allowed establishing, as a scientific contribution, new theories about the behavior of the hardening mechanisms in the plastic field, such as the mutual determination of the microstructural parameters and the mechanical properties of said alloys and, in turn, with the parameters of the casting process, and vice versa.
Which, in turn, by analogical distinction, allowed making predictions and inferences with greater precision about the fatigue behavior at low cycle of automotive components, such
as, for example, the cylinder head, this being the technological contribution of the study. In such a way that, said alloys presented a kinematic to isotropic hardening model, that is, they presented a permanent softening, in the first hysteresis cycle, passing through a stable cyclic hardening, while close to fatigue fracture, they presented a cyclical softening.
Through fractography, it was determined that the defects inherent to the casting process, such as, for example, porosity close to the surface and of greater size, dominated the nucleation phenomenon; fatigue striations were also observed, as well as damaged, cracked and detached particles. On the other hand, the crack propagation phenomenon was caused by the coalescence of microcracks, through regions with a higher density of defects and brittle particles, until they grew into macroscopic cracks and, finally, presenting a ductile fracture mode Coalescence, that is, the union and interaction between
micropores, accelerated the fracture. This made it possible to demonstrate that the nature of the particles with the highest presence, in the first hysteresis cycle, determined the
behavior of the Bauschinger effect of the alloys A319 T7, A356 T6 and A356+0.5Cu T6, decreasing this phenomenon as it increased plastic deformation and, in turn, adjusting to a Masing-type behavior
Insoluble soybean polysaccharides: Obtaining and evaluation of their O/W emulsifying properties
The aims of this work were to obtain different samples of insoluble soybean polysaccharides (ISPS) from defatted soy flour and to study their potential application as O/W emulsifier. In this regard, the insoluble residue (okara) resulting from an aqueous extraction (60 °C, pH 9.0), was submitted to an acidic extraction (pH 3.5, 120 °C) without or with a pretreatment (high pressure homogenization or sonication treatment). The insoluble residues of these extractions were dried (oven, 70 °C or vacuum post-treatment with 2-propanol, 40 °C) yielding different ISPS samples. Aqueous dispersions of ISPS samples (1?2% w/w, pH 3 and 7), were used to prepare coarse and fine O/W emulsions. Emulsion stability against creaming and coalescence processes, and the rheological behavior were analyzed. ISPS samples obtained by okara pretreatment and vacuum dried post-treatment with 2-propanol allow to produces emulsions with high values of flocculation degree, increasing the stability of the particle size, and allowing the formation of stronger gel-like emulsions. These pretreatments expose internal sites of the polysaccharide and protein structures, increasing their superficial hydrophobicity and, therefore, allow a strong absorption of the macromolecules at the oil-water interface and/or the formation of external layers, increasing the rigidity of the interfacial film and contributing to the formation of hydrated flocs, Also, these treatments could solubilize certain compounds in okara that would interfere negatively in the formation of the interfacial film. Particularly, sample obtained by high pressures homogenization of the okara presented the best emulsifying properties and it was not significantly affected by variations in the pH of the emulsion. The results of this research work demonstrate a high potential of application of the ISPS samples as O/W emulsifier, under acid and neutral conditions, increasing the added value of an important by-product of the soybean industry.Fil: Porfiri, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos; ArgentinaFil: Vaccaro, J.. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos; ArgentinaFil: Stortz, Carlos Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Navarro, Diego Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Wagner, Jorge Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos; ArgentinaFil: Cabezas, Dario Marcelino. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos; Argentin
Numerical and experimental analysis of automotive turbocharger compressor aeroacoustics at different operating conditions
Centrifugal compressor aeroacoustics are analyzed by means of a three-dimensional CFD model. Three operating points at nominal compressor speed are simulated ranging from best efficiency point to near-surge conditions. Experimental measurements are obtained using a steady flow rig mounted on an anechoic chamber. URANS and DES predictions of compressor global variables and pressure spectra are compared against experimental measurements. Flow-induced noise increases as the operating point moves toward surge line. Stall at the suction side of the blades exists even for high mass flow conditions, causing a high frequency boundary layer oscillation. Low momentum cells rotating at the diffuser are found at points closer to surge, causing the so-called whoosh noise. Inducer rotating stall is also present at these conditions. Point closest to surge shows a rotating tornado-type vortex at the inducer, determining a moving low pressure region that increases low frequency noise content.The equipment used in this work has been partially supported by the Spanish Ministerio de Economia y Competitividad through grant no. TRA2012-36954 and by FEDER project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)" framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economia y Competitividad. Part of the computational resources used in this work have been provided by Super computing Center of Universitat Politecnica de Valencia and are thus gratefully acknowledged.Broatch Meza, A.; Galindo, J.; Navarro García, R.; García Tíscar, J. (2016). Numerical and experimental analysis of automotive turbocharger compressor aeroacoustics at different operating conditions. International Journal of Heat and Fluid Flow. 61B:245-255. https://doi.org/10.1016/j.ijheatfluidflow.2016.04.003S24525561
The analysis of the basketball coach speech during the moments of game and pause in relation to the performance in competition
In the area of the professional competition, the coach is a fundamental part in the management of a team and more concretely in the game planning. During the competition, the management of the times of pause and times out as well as the conduct of the coach during the same ones is an aspect to analyze in the sports performance. It is for this that it becomes necessary to know some of the behaviors that turn out to be more frequent by the coach and that are more related to a positive performance of his players. For it there has been realized a study of 7 cases of expert coaches in those that his verbal behavior has observed during 4 games. It has focused on the content of the information only to verbal level, on his meaning. The information that have been obtained in the study shows a major quantity of information elaborated during the pauses of the games and a major tactical content with regard to the moments of game. On the other hand, a relation exists between a major number of questions and a minor number of psychological instructions when the score is adverse, whereas in case of victory, a direct relation does not exist with any category. The rest of categories of the speech do not meet influenced directly for the result, for what it is not possible to consider a direct and immediate relation between the coach verbal behavior during the pauses and the result of the game, except in punctual moments
Endogenous Antioxidants: A Review of their Role in Oxidative Stress
Oxidative stress (OxS) constitutes a disturbance caused by an imbalance between the generation of free radicals and antioxidant system, which causes damage to biomolecules. This, in turn, may lead the body to the occurrence of many chronic degenerative diseases. Therefore, it is very important to know the functioning of those endogenous (and exogenous) antioxidants systems to prevent such diseases. Due to evolutionary conditions in living beings, among other functions have been developed and selected defense systems against the deleterious action of free radicals. Such systems are intrinsic in cells (at level intracellular and extracellular) and act together with the dietary exogenous antioxidants. All these antioxidant systems have very important role in preserving the oxide/reduction equilibrium in the cell. To understand the role of the transcription factor Nrf2 in regulating the processes of antioxidant defense, it must also know the role of many of the endogenous antioxidants that occur because of its activation. Therefore, this chapter makes a literature review of the most important general aspects of endogenous antioxidant systems, which will provide another point of view from which to approach the study and treatment of many chronic degenerative diseases, such as diabetes, hypertension, and Parkinson
Acoustic characterization of automotive turbocompressors
The performance of different experimental techniques proposed in the literature for acoustic characterization was
assessed through the study of the noise generated by the compressor of an automotive turbocharger under different
working conditions in an engine test cell. The most critical restrictions of in-duct intensimetry methods regarding frequency
limitations are presented and experimentally demonstrated. The results provided by those methods were correlated
against a reference intensity probe. A beamforming method based on three-sensor-phased arrays appears to be
the most reliable approach in the plane wave range, presenting higher accuracy than the more common two-microphone
method and simple pressure level measurements. Also, preliminary results from a novel radiated noise quantification
technique based on acoustic particle velocity are presented and discussed. The results indicate that further research on
this topic is required.This work has been partially supported by the Spanish Ministerio de Economia y Competitividad through grant no. TRA2012-36954. The equipment used in this work has been partially supported by FEDER project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06),'' framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economia y Competitividad.Torregrosa, AJ.; Broatch Jacobi, JA.; Navarro García, R.; García Tíscar, J. (2015). Acoustic characterization of automotive turbocompressors. International Journal of Engine Research. 16(1):31-37. https://doi.org/10.1177/1468087414562866S313716
Live Streaming Speech Recognition Using Deep Bidirectional LSTM Acoustic Models and Interpolated Language Models
[EN] Although Long-Short Term Memory (LSTM) networks and deep Transformers are now extensively used in offline ASR, it is unclear how best offline systems can be adapted to work with them under the streaming setup. After gaining considerable experience on this regard in recent years, in this paper we show how an optimized, low-latency streaming decoder can be built in which bidirectional LSTM acoustic models, together with general interpolated language models, can be nicely integrated with minimal performance degradation. In brief, our streaming decoder consists of a one-pass, real-time search engine relying on a limited-duration window sliding over time and a number of ad hoc acoustic and language model pruning techniques. Extensive empirical assessment is provided on truly streaming tasks derived from the well-known LibriSpeech and TED talks datasets, as well as from TV shows on a main Spanish broadcasting station.This work was supported in part by European Union's Horizon 2020 Research and Innovation Programme under Grant 761758 (X5gon), and 952215 (TAILOR) and Erasmus+ Education Program under Grant Agreement 20-226-093604-SCH, in part by MCIN/AEI/10.13039/501100011033 ERDF A way of making Europe under Grant RTI2018-094879-B-I00, and in part by Generalitat Valenciana's Research Project Classroom Activity Recognition under Grant PROMETEO/2019/111. Funding for open access charge: CRUE-Universitat Politecnica de Valencia. The associate editor coordinating the review of this manuscript and approving it for publication was Prof. Lei Xie.Jorge-Cano, J.; Giménez Pastor, A.; Silvestre Cerdà, JA.; Civera Saiz, J.; Sanchis Navarro, JA.; Juan, A. (2022). Live Streaming Speech Recognition Using Deep Bidirectional LSTM Acoustic Models and Interpolated Language Models. IEEE/ACM Transactions on Audio Speech and Language Processing. 30:148-161. https://doi.org/10.1109/TASLP.2021.3133216S1481613
- …