Numerical modeling of strain rate hardening effects on viscoplastic behavior of metallic materials

The main goal of the present work is to provide a finite strain elasticviscoplastic framework to numerically account for strain, strain rate hardening, and viscous effects in cold deformation of metallic materials. The aim is to provide a simple and robust numerical framework capable of modeling the main macroscopic behavior associated with high strain rate plastic deformation of metals. In order to account for strain rate hardening effects at finite strains, the hardening rule involves a rate dependent saturation hardening, and it accounts for linear hardening prevailing at latter deformation stages. The numerical formulation, finite element implementation, and constitutive modeling capabilities are assessed by means of decremental strain rate testing and constant strain rate loading followed by stress relaxation. The numerical results have demonstrated the overall framework can be an efficient numerical tool for simulation of plastic deformation processes where strain rate history effects have to be accounted for

Some numerical verification examples for plane stress elasto-viscoplasticity

This paper presents analytical, semi-analytical and numerical reference examples which can be employed for code verification of elasto-viscoplastic models under plane stress conditions. Mainly because of the overstress function the algorithms traditionally employed in elasto-plastic implementations must be rewritten to correctly impose the plane stress state along with the viscoplastic flow. The viscoplastic formulation presented here considers the strain-rate hardening effects by means of a hardening law that are assumed to have terms depending on the strain rate, which removed can represent a Voce type hardening. The proposed verification tests were employed for the numerical verification of an in-house implementation of the so-called stress-projected procedure inside the finite element method context. Although the focus of this paper is on the stressprojected algorithms the examples presented here can be employed for the verification of other algorithms intended to impose the plane stress state in viscoplasticit

Extra-virgin olive oil phenols block cell cycle progression and modulate chemotherapeutic toxicity in bladder cancer cells

Epidemiological data indicate that the daily consumption of extra‑virgin olive oil (EVOO), a common dietary habit of the Mediterranean area, lowers the incidence of certain types of cancer, in particular bladder neoplasm. The aim of the present study was to evaluate the antiproliferative activity of polyphenols extracted from EVOO on bladder cancer (BCa), and to clarify the biological mechanisms that trigger cell death. Furthermore, we also evaluated the ability of low doses of extra‑virgin olive oil extract (EVOOE) to modulate the in vitro activity of paclitaxel or mitomycin, two antineoplastic drugs used in the management of different types of cancer. Our results showed that EVOOE significantly inhibited the proliferation and clonogenic ability of T24 and 5637 BCa cells in a dose‑dependent manner. Furthermore, cell cycle analysis after EVOOE treatment showed a marked growth arrest prior to mitosis in the G2/M phase for both cell lines, with the subsequent induction of apoptosis only in the T24 cells. Notably, simultaneous treatment of mitomycin C and EVOOE reduced the drug cytotoxicity due to inhibition of ROS production. Conversely, the co‑treatment of T24 cells with paclitaxel and the polyphenol extract strongly increased the apoptotic cell death at each tested concentration compared to paclitaxel alone. Our results support the epidemiological evidence indicating that olive oil consumption exerts health benefits and may represent a starting point for the development of new anticancer strategies

Nuevos desafíos: la formación emprendedora

El reto de las universidades exige combinar su actividad científica y de investigación con su capacidad para formar profesionales que puedan incorporarse al ámbito laboral. Si bien lo que debe prevalecer es la preparación de egresados con una visión crítica de la realidad, su misión actual no debe limitarse a prepararlos para que consigan un empleo sino afrontar el desafío de educarlos desde una perspectiva más amplia que los estimule a cuestionar e introducir cambios en la sociedad, a través de una actitud prospectiva y anticipadora. Ante el déficit de empleo, la capacidad de emprender y el desarrollo de estrategias de cooperación y colaboración resultan fundamentales. Estas competencias son esenciales para la formulación del proyecto profesional, que podrá ser propio o de terceros y que incluye, entre otros: el desarrollo de la iniciativa, el fortalecimiento de la toma de decisión, la capacidad de asumir riesgos y la participación a través del perfeccionamiento del liderazgo, la conducción activa de ideas y proyectos, del trabajo en equipo, de la valoración de la creatividad, la observación, la autonomía, la flexibilidad, la adaptabilidad, el pensamiento analítico. Competencias que, desde edades tempranas, hay que desarrollar en el proceso de enseñanza y aprendizaje

Prenúncios da emancipação feminina: o despontar da nova mulher em De amor y de sombra e Uma varanda sobre o silêncio

IX Congresso Brasileiro de Hispanistas realizado nos dias 22 a 25 agosto 2016A preocupação relativa à temática feminina e às construções sociais dos papéis inerentes ao gênero feminino tem encontrado, nos tempos atuais, um merecido espaço de acolhida por parte dos estudiosos e dos pesquisadores da área, no intento de desconstruir o mito patriarcal, segundo o qual “o mundo sempre pertenceu aos machos” (BEAUVOIR, 2009). No presente estudo, analisaremos o comportamento feminino concernente aos avanços sociais e individuais em relação ao direito da mulher de encontrar um devido espaço de realização pessoal. Para tanto, tomaremos como base as personagens centrais dos romances De amor y de sombra e Uma varanda sobre o silêncio, escritos por Isabel Allende (1942) e Josué Montello (19172006), ambas no ano de 1984. O objetivo deste estudo consiste em revelar aos estudiosos da temática feminina que, dentre as principais realizações da mulher, nos tempos atuais, encontramos sentido também em realizála como pessoa e profissionalmente, e não apenas na maternidade e na procriação (SWAIN, 2007), os principais pilares da significação femininaUNILA­-UNIOEST

USULAN PERBAIKAN EFEKTIVITAS KINERJA PEKERJA DI DEPARTEMEN VENEER DENGAN MENGGUNAKAN OVERALL LABOR EFFECTIVENESS (OLE) DAN ROOT CAUSE ANALYSIS: (STUDI KASUS: PT. ASIA FORESTAMA RAYA)

PT. Asia Forestama Raya (PT. AFR) yang bertempat di tepian Sungai Siak, Kelurahan Limbungan, Kecamatan Rumbai Pesisir, Kota Pekanbaru, Riau merupakan salah satu perusahaan yang mengolah hasil hutan (kayu) menjadi kayu lapis (plywood). Manajemen Sumber Daya Manusia (MSDM) yang baik yaitu disaat perusahaan dapat memanfaatkan sumber daya yang dimiliki agar tercapainya produktivitas yang baik. Berdasarkan analisa awal dilihat dari data produksi yang tidak mencapai target, turnover pekerja sebesar 22,08% dan data cacat yang sebagian besar dihasilkan dari bagian veneer serta bagian bahan baku dan mesin diketahui tidak memiliki hambatan, sehingga masalah yang perlu diperbaiki yaitu kurangnya kinerja pekerja. Veneer merupakan komponen utama dari triplek dan kualitas baik buruknya plywood dilihat dari veneer. Efektivitas Keseluruhan Pekerja (Overall Labor Effectiveness/OLE) adala suatu metode digunakan untuk mengukur efektivitas, pemanfaatan, kinerja dan kualitas pekerja yang berpengaruh terhadap output yang dihasilkan di lantai produksi serta profitabilitas melalui pengukuran konstribusi dari pekerja. Nilai OLE departemen veneer sebesar 66,15% kurang dari standar dunia yaitu 85%, nilai ini termasuk dalam tingkat wajar (fairly typical level) pada standar dunia. Setelah nilai OLE diketahui maka tahap selanjutnya yaitu mengetahui akar penyebab masalah menggunakan Root Cause Analysis (RCA). Adapun penyebab utama kurangnya kinerja OLE yaitu penjadwalan waktu kerja tidak baik, penumpukan bahan, pekerja kurang terampil, pada proses perekrutan, tidak adanya pengendalian kualitas pekerja, ketidak puasan pekerja dan kurang baiknya interaksi antar pekerja dan lingkungan. Berdasarkan akar penyebab masalah tersebut diberikan usulan perbaikan yaitu program pelatiham kerja, sanksi pengurangan gaji untuk pekerja yang tidak memenuhi target, rancangan kerja untuk meningkatkan produktivitas serta rancanagn alur perekrutan  kerja

Dust formation in the winds of AGBs: the contribution at low metallicities

We present new models for the evolution of stars with mass in the range 1Msun < M < 7.5Msun, followed from the pre-main-sequence through the asymptotic giant branch phase. The metallicity adopted is $Z=3*10^{-4} (which, with an alpha-enhancement of +0.4, corresponds to [Fe/H]=-2). Dust formation is described by following the growth of dust grains of various types as the wind expands from the stellar surface. Models with mass M>3Msun experience Hot Bottom Burning, thus maintaining the surface C/O below unity. Unlike higher Z models, the scarcity of silicon available in the envelope prevents the formation of silicates in meaningful quantities, sufficient to trigger the acceleration of the wind via radiation pressure on the dust grains formed. No silicate formation occurs below a threshold metallicity of Z=10^{-3}. Low--mass stars, with M< 2.5Msun become carbon stars, forming solid carbon dust in their surroundings. The total dust mass formed depends on the uncertain extent of the inwards penetration of the convective envelope during the Third Dredge--Up episodes following the Thermal Pulses. Carbon grains have sizes 0.08 micron < a_C < 0.12 micron and the total amount of dust formed (increasing with the mass of the star) is M_C=(2-6)*10^{-4}Msun. Our results imply that AGB stars with Z=3*10^{-4} can only contribute to carbon dust enrichment of the interstellar medium on relatively long timescales, > 300 Myr, comparable to the evolutionary time of a 3Msun star. At lower metallicities the scarcity of silicon available and the presence of Hot Bottom Burning even in M< 2Msun, prevents the formation of silicate and carbon grains. We extrapolate our conclusion to more metal--poor environments, and deduce that at Z < 10^{-4} dust enrichment is mostly due to metal condensation in supernova ejecta.Comment: 13 pages, 8 figures, accepted for publication on MNRA

Probabilistic identification of rockfall source areas at regional scale in El Hierro (Canary Islands, Spain)

Abstract Modelling rockfall phenomena is complex and requires various inputs, including an accurate location of the source areas. Source areas are controlled by geomorphological, geological, or other geo-environmental factors and may largely influence the results of the modelling. In the Canary Islands, rockfalls are extremely common and pose a major threat to society, costing lives, disrupting infrastructure, and destroying livelihoods. In 2011, the volcanic event on the island of El Hierro triggered numerous rockfalls that affected strategic infrastructures, with a substantial impact on the local population. During the emergency, the efforts performed to map the source areas and to model the rockfalls in the considerably steep landscape characterising the island were not trivial. To better identify the rockfall source areas, we propose a probabilistic modelling framework that applies a combination of multiple statistical models using the source area locations mapped in the field as the dependent variable and a set of thematic data as independent variables. The models use as input morphometric parameters derived from the Digital Elevation Model and lithological data as an expression of the mechanical behaviour of the rocks. The analysis of different training and validation scenarios allowed us to test the model sensitivity to the input data, select the optimal model training configuration, and evaluate the model applicability outside the training areas. The final map obtained from the model for the entire island of El Hierro provides the probability of a given location being a potential source area and can be used as the input for rockfall runout simulation modelling

Una aproximación conceptual de las empresas de base tecnológica

Resulta indiscutible el rol del conocimiento y la innovación para el desarrollo de las empresas y naciones. Uno de los indicadores de innovación es la transferencia de conocimiento desde las Universidades o Centros de Investigación que puede manifestarse en la creación de empresas de base tecnológica. Numerosas investigaciones que toman como objeto de estudio a este tipo de empresas avalan su contribución al desarrollo económico de la sociedad. No obstante ello, aún no hay consenso acerca de una definición clara y generalizable; lo que trae aparejado la dificultad de realizar comparaciones históricas y geográficas. El siguiente trabajo se propone una revisión bibliográfica en términos históricos como actuales sobre el concepto de Empresa de Base Tecnológica, con el fin de realizar un análisis comparativo que refleje la evolución de este término a lo largo de los años así como también la concepción actual adoptada por los principales organismos de ciencia y técnica del Mercosur. Para ello se realizó un análisis exploratorio y comparativo de la bibliografía existente en la temática así como también las definiciones adoptadas por los referentes señalados. De esta manera, el trabajo pretende lograr una aproximación conceptual que sea el resultado del análisis de las diversas posturas planteadas y que se enmarque dentro de la realidad de los países de la región.publishedVersio