2,222 research outputs found

    Estimation of specific cutting energy in an S235 alloy for multi-directional ultrasonic vibration-assisted machining using the Finite聽Element Method

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    The objective of this work is to analyze the influence of the vibration-assisted turning process on the machinability of S235 carbon steel. During the experiments using this vibrational machining process, the vibrational amplitude and frequency of the cutting tool were adjusted to drive the tool tip in an elliptical or linear motion in the feed direction. Furthermore, a finite element analysis was deployed to investigate the mechanical response for different vibration-assisted cutting conditions. The results show how the specific cutting energy and the material鈥檚 machinability behave when using different operational cutting parameters, such as vibration frequency and tool tip motion in the x-axis, y-axis, and elliptical (x-y plane) motion. Then, the specific cutting energy and material鈥檚 machinability are compared with a conventional turning process, which helps to validate the finite element method (FEM) for the vibration-assisted process. As a result of the operating parameters used, the vibration-assisted machining process leads to a machinability improvement of up to 18% in S235 carbon steel. In particular, higher vibration frequencies were shown to increase the material鈥檚 machinability due to the specific cutting energy decrease. Therefore, the finite element method can be used to predict the vibration-assisted cutting and the specific cutting energy, based on predefined cutting parameters.Peer ReviewedPostprint (published version

    Tombs, teeth and culture: 2,500 years of microevolution and the origins of the prehispanic societies in the Calima archaeological region of Colombia, South America

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    El objetivo principal de esta investigaci贸n es el de contribuir a la discusi贸n sobre el origen de las sociedades prehisp谩nicas formativas y tard铆as de la regi贸n arqueol贸gica Calima de Colombia. Los restos dentales examinados en esta investigaci贸n pertenecen a 114 individuos distribuidos en siete cementerios ubicados en la regi贸n arqueol贸gica Calima. Se observaron 15 rasgos no m茅tricos dentales aplicando el m茅todo de ASUDAS (Arizona State University Dental Anthropology System). Se aplic贸 la Medida Media de Divergencia MMD en las comparaciones entre pares de muestras colombianas de los periodos Formativo y Tard铆o de la regi贸n arqueol贸gica. El an谩lisis de coordenadas principales realizado muestra dos grupos. La sociedad tard铆a Sonso expone diferencias significativas con relaci贸n a Ilama. El origen Ilama se explica como resultado de migraciones desde el noroccidente del pa铆s durante el periodo Formativo temprano (6000 ? 4000 AP), mientras que el origen Sonsoide proviene del sur del pa铆s durante 茅pocas Formativas tard铆as (2000 ? 1500 AP).umen El objetivo principal de esta investigaci贸n es el de contribuir a la discusi贸n sobre el origen de las sociedades prehisp谩nicas formativas y tard铆as de la regi贸n arqueol贸gica Calima de Colombia. Los restos dentales examinados en esta investigaci贸n pertenecen a 114 individuos distribuidos en siete cementerios ubicados en la regi贸n arqueol贸gica Calima. Se observaron 15 rasgos no m茅tricos dentales aplicando el m茅todo de ASUDAS (Arizona State University Dental Anthropology System). Se aplic贸 la Medida Media de Divergencia MMD en las comparaciones entre pares de muestras colombianas de los periodos Formativo y Tard铆o de la regi贸n arqueol贸gica. El an谩lisis de coordenadas principales realizado muestra dos grupos. La sociedad tard铆a Sonso expone diferencias significativas con relaci贸n a Ilama. El origen Ilama se explica como resultado de migraciones desde el noroccidente del pa铆s durante el periodo Formativo temprano (6000 鈥 4000 AP), mientras que el origen Sonsoide proviene del sur del pa铆s durante 茅pocas Formativas tard铆as (2000 鈥 1500 AP)Fil: Rodriguez Florez, Carlos David. Universidad Nacional de Cordoba. Facultad de Ciencias Exactas, Fisicas y Naturales; Argentina;Fil: Colantonio, Sonia Edith. Consejo Nacional de Investigaciones Cient铆ficas y T茅cnicas. Centro Cient铆fico Tecnol贸gico - CONICET - C贸rdoba. Centro de Investigaciones y Estudio sobre Cultura y Sociedad; Argentina

    EFFECT OF PLANT POPULATION IN GREAT NORTHERN AND PINTO BEAN PRODUCTION IN WESTERN NEBRASKA

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    INTRODUCTION In this project we explored the effect of plant population and row spacing on the yield and quality of great northern and pinto beans grown in Nebraska. This project builds on the findings from a preliminary non-replicated great northern variety trial conducted at Morrill, NE in 2014. That trial included four great northern cultivars with different plant architecture. In general, yields were reduced 18.8% (795 kg ha-1) when plant population increased from 251,152 to 300,715 plants ha-1. Yield reduction was greatest in 鈥6107鈥 (24.7%) followed by 鈥楳arquis鈥 (20.1%), 鈥楤eryl-R鈥 (15.5%) and 鈥楥oyne鈥 (14.0%). In the current project we used replicated trials to evaluate the impact of plant population on two great northern and two pinto bean cultivars. Within each market class, one cultivar had a prostrate (III) and the other had an upright (II) growth habit. Our goal was to identify the optimal plant population and row spacing for each cultivar. MATERIALS AND METHODS This study was conducted during 2015 at the PREC-Scottsbluff, NE. Two great northern, 鈥楳arquis鈥 (III) and 鈥楧raco鈥 (II), and two pinto cultivars, Montrose (III) and Sinaloa (II) were planted in separate experiments at two row spacing (15 and 30 inches) and four plant populations. Target populations for the 30-inch row spacing were 45,000, 80,000, 100,000, and 120,000 plants/acre. Target populations for the 15-inch row spacing were 80,000, 100,000, 120,000, and 150,000 plants/acre. Four and seven rows were planted for the 30- and 15-inch row spacing experiments, respectively

    EFFECT OF PLANT POPULATION IN GREAT NORTHERN AND PINTO BEAN PRODUCTION IN WESTERN NEBRASKA

    Get PDF
    INTRODUCTION In this project we explored the effect of plant population and row spacing on the yield and quality of great northern and pinto beans grown in Nebraska. This project builds on the findings from a preliminary non-replicated great northern variety trial conducted at Morrill, NE in 2014. That trial included four great northern cultivars with different plant architecture. In general, yields were reduced 18.8% (795 kg ha-1) when plant population increased from 251,152 to 300,715 plants ha-1. Yield reduction was greatest in 鈥6107鈥 (24.7%) followed by 鈥楳arquis鈥 (20.1%), 鈥楤eryl-R鈥 (15.5%) and 鈥楥oyne鈥 (14.0%). In the current project we used replicated trials to evaluate the impact of plant population on two great northern and two pinto bean cultivars. Within each market class, one cultivar had a prostrate (III) and the other had an upright (II) growth habit. Our goal was to identify the optimal plant population and row spacing for each cultivar. MATERIALS AND METHODS This study was conducted during 2015 at the PREC-Scottsbluff, NE. Two great northern, 鈥楳arquis鈥 (III) and 鈥楧raco鈥 (II), and two pinto cultivars, Montrose (III) and Sinaloa (II) were planted in separate experiments at two row spacing (15 and 30 inches) and four plant populations. Target populations for the 30-inch row spacing were 45,000, 80,000, 100,000, and 120,000 plants/acre. Target populations for the 15-inch row spacing were 80,000, 100,000, 120,000, and 150,000 plants/acre. Four and seven rows were planted for the 30- and 15-inch row spacing experiments, respectively

    The GuideView System for Interactive, Structured, Multi-modal Delivery of Clinical Guidelines

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    GuideView is a computerized clinical guideline system which delivers clinical guidelines in an easy-to-understand and easy-to-use package. It may potentially enhance the quality of medical care or allow non-medical personnel to provide acceptable levels of care in situations where physicians or nurses may not be available. Such a system can be very valuable during space flight missions when a physician is not readily available, or perhaps the designated medical personnel is unable to provide care. Complex clinical guidelines are broken into simple steps. At each step clinical information is presented in multiple modes, including voice,audio, text, pictures, and video. Users can respond via mouse clicks or via voice navigation. GuideView can also interact with medical sensors using wireless or wired connections. The system's interface is illustrated and the results of a usability study are presented

    Los efectos del cr茅dito bidireccional entre conglomerados financieros en el mercado repo

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    Examinamos c贸mo la estructura del mercado, el poder de mercado y el riesgo sist茅mico responden a relaciones de financiamiento estrechas e intensas entre conglomerados financieros (CF) en mercados de repos bilaterales descentralizados. Usando datos a nivel transaccional de M茅xico, documentamos relaciones de financiamiento persistentes y estables entre bancos y fondos afiliados a CF con dos caracter铆sticas distintivas: primero, las transacciones de financiamiento son bidireccionales, es decir, un par dado de CF rivales proporciona financiamiento mutuo en el mismo d铆a; segundo, las transacciones bidireccionales se ejecutan a tasas promedio m谩s bajas en comparaci贸n con las transacciones unidireccionales. Mostramos que los pr茅stamos bidireccionales entre los CF favorecen la concentraci贸n del mercado, aumentan el poder de mercado de los fondos afiliados a los CF y empeoran los t茅rminos de intercambio de las transacciones de cr茅dito de bancos y fondos independientes. Adem谩s, encontramos que la contribuci贸n individual a nivel de banco al riesgo sist茅mico aumenta con los pr茅stamos bidireccionales.We examine how market structure, market power, and systemic risk respond to close and intense lending relationships between financial conglomerates (FCs) in non-centrally cleared bilateral repo. Using transaction-level data from Mexico, we document persistent and stable funding relationships between FC-affiliated banks and funds with two distinctive features: first, funding transactions are two-way, that is, a given pair of rival FCs provide lending to one another on the same day; second, two-way transactions are executed at lower average rates than one-way transactions. We show that two-way lending between FCs favours both market concentration and market power of FC-affiliated funds, and worsens the terms of trade of independent banks鈥 and funds鈥 lending. Furthermore, we find that the bank-level contribution to systemic risk increases with two-way lending.Los efectos del cr茅dito bidireccional entre conglomerados financieros en mercados repo bilaterales Enfoque El mercado de acuerdos de recompra (repo) es una parte importante de los sistemas financieros en todo el mundo. En este mercado, los bancos y otras instituciones financieras obtienen liquidez contra garant铆as con el compromiso de recomprar esas garant铆as en un corto per铆odo de tiempo. Precisamente por su importancia como fuente de liquidez de corto plazo para instituciones expuestas a corridas, los mercados repo tambi茅n tienen el potencial de generar crisis que pueden involucrar a todo el sistema financiero. Recientemente, la creciente concentraci贸n de los mercados financieros en unos pocos grandes conglomerados financieros (CF) est谩 causando nuevas preocupaciones sobre los efectos de los mercados repo en la estabilidad de los sistemas. En este art铆culo, examinamos c贸mo la estructura de mercado, el poder de mercado y el riesgo sist茅mico responden a relaciones de pr茅stamo estrechas e intensas entre conglomerados financieros (CF) en mercados repo en los que las partes interact煤an directamente sin la intervenci贸n de una autoridad central o intermediario. Para esto, usamos datos transaccionales del mercado repo mexicano registrados por el Banco Central de M茅xico entre el 1潞. de enero de 2006 y el 8 de febrero de 2018, construimos medidas de profundidad e intensidad de las relaciones bidireccionales entre CF basadas en el volumen total de cr茅dito y el n煤mero de cr茅ditos de cada par, respectivamente, y llevamos a cabo un conjunto de regresiones para determinar el efecto de la profundidad e intensidad de las relaciones bidireccionales de cr茅dito entre pares de CF en varias variables de inter茅s indicadoras del grado de concentraci贸n del mercado de oferta de liquidez, poder de mercado de los fondos de inversi贸n y contribuci贸n de los bancos al riesgo del sistema. Contribuci贸n Las contribuciones de este art铆culo son principalmente tres. Primero, documentamos un fen贸meno nuevo en la literatura de relacionamiento de cr茅dito entre instituciones: la existencia de transacciones de cr茅dito bidireccionales y contempor谩neas entre bancos y fondos afiliados a CF a tasas promedio m谩s bajas en comparaci贸n con las transacciones unidireccionales. Segundo, mostramos que este tipo de relaciones tiene efectos estad铆stica y econ贸micamente significativos en el nivel de competencia del mercado de fondeo repo y en la estabilidad del sistema financiero. Finalmente, nuestro trabajo pone la lupa sobre una vulnerabilidad a la que pueden estar expuestos todos aquellos mercados repo con caracter铆sticas similares a las de M茅xico: bilateral, sin intervenci贸n de una autoridad central y en el que las partes conocen la identidad de su contraparte. Resultados Mostramos que los pr茅stamos bidireccionales entre los CF favorecen la concentraci贸n del mercado, aumentan el poder de mercado de los fondos afiliados a los CF y empeoran los t茅rminos de intercambio de los pr茅stamos de bancos y fondos independientes. Adem谩s, encontramos que la contribuci贸n individual a nivel bancario al riesgo sist茅mico aumenta con los pr茅stamos bidireccionales. Frase destacada: Nuestro trabajo pone la lupa sobre una vulnerabilidad a la que pueden estar expuestos todos aquellos mercados repo con caracter铆sticas similares a las de M茅xico: bilateral, sin intervenci贸n de una autoridad central y en el que las partes conocen la identidad de su contraparte

    Schwarz alternating domain decomposition approach for the solution of mixed heat convection flow problems based on the method of approximate particular solutions

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    The incompressible two-dimensional Navier-Stokes equations including thermal energy balance equation are solved by the recently developed Method of Approximate Particular Solutions (MAPS). In a previous authors鈥 work this method was implemented to solve the two-dimensional Stokes equations by employing the pressure and velocity particular solutions obtained by Oseen鈥檚 decomposition with the Multiquadric (MQ) RBF as non-homogeneous term. A pressure-velocity linkage strategy is not required since the pressure particular solutions are obtained from the velocity ones. In the present contribution, the Navier-Stokes equations with Boussinesq approximation are solved by linearizing the convective term in a Picard iterative scheme. With the velocity values obtained at each of the Picard iterations, the energy conservation equation is solved by the MAPS by approximating temperature with the particular solutions of a Poisson problem with the MQ as a forcing term. With the aim of improving the computational efficiency of the global strategy, the two-dimensional domain is split into overlapped rectangular subdomains where the Schwarz Alternating Algorithm is employed to find a solution by using velocity and temperatures values from neighbouring zones as boundary conditions. The mixed convection lid-driven cavity flow problem is solved for moderate Reynolds and low Richardson numbers with the aim of validating the proposed method

    M茅todo ABN como alternativa matem谩tica de impacto positivo en el rendimiento y en la memoria de trabajo

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    La palabra 鈥淢atem谩ticas鈥 siempre ha supuesto para la mayor铆a de las personas un compendio de ideas prefijadas negativas. Generaci贸n tras generaci贸n se ha empleado el m茅todo tradicional sin cuestionarlo en exceso, y actualmente contin煤a siendo el m茅todo m谩s extendido en nuestros centros educativos. Se le denomina CBC (Cerrado Basado en Cifras) a este anticuado m茅todo centrado en quehaceres mec谩nicos exigiendo una abstracci贸n por encima de sus posibilidades al alumnado, conllevando un bajo rendimiento matem谩tico, as铆 como un desaprovechamiento de habilidades innatas cognitivas
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