3,682 research outputs found

    Logistics operation hiring process in Colombia: the implementation of a crosscutting logistics operator

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    Este art铆culo tiene como objetivo presentar los criterios que se deben tener en cuenta para contratar los servicios de los operadores log铆sticos. Las evidencias presentadas en este art铆culo se basan en informaci贸n obtenida a trav茅s de encuestas, entrevistas, estudio de casos, sondeos y revisi贸n de literatura. La principal conclusi贸n muestra que la claridad contractual es clave en el surgimiento de un nuevo modelo de negocio que puede impulsar el desarrollo del pa铆s. Las empresas deben ver la contrataci贸n log铆stica con una oportunidad estrat茅gica, al igual que pensar en cada posible situaci贸n que se pueda presentar para as铆 plasmar un curso de acci贸n en el contratoThe main objective of this paper is to present opinions that must be bared in mind when hiring ser颅vices from logistics operators. The evidence presented in this paper was obtained from information gathered from surveys, interviews, case studies, polls, and literature reviews. The main conclusion shows that contractual clarity is key during the upsurge of a new business model that can drive the development of the country. Businesses must see the hiring of logistics services as a strategic op颅portunity as well as listing all the possible situations that can arise in order to include in the contract a course of action to be followed

    Method for landslides detection with semi-automatic procedures: The case in the zone center-east of Cauca department, Colombia

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    Landslides are a common natural hazard that causes human casualties, but also infrastructure damage and land-use degradation. Therefore, a quantitative assessment of their presence is required by means of detecting and recognizing the potentially unstable areas. This research aims to develop a method supported on semiautomatic methods to detect potential mass movements at a regional scale. Five techniques were studied: Morphometry, SAR interferometry (InSAR), Persistent Scatterer InSAR (PS-InSAR), SAR polarimetry (PolSAR) and NDVI composites of Landsat 5, Landsat 7, and Landsat 8. The case study was chosen within the mid-eastern area of the Cauca state, which is characterised by its mountainous terrain and the presence of slope instabilities, officially registered in the CGS-SIMMA landslide inventory. This inventory revealed that the type `slide' occurred with 77.4% from the entire registries, `fall' with 16.5%, followed by `creeps' with 3%, flows with 2.6%, and `lateral spread' with 0.43%. As a result, we obtained the morphometric variables: slope, CONVI, TWI, landform, which were highly associated with landslides. The effect of a DEM in the processing flow of the InSAR method was similar for the InSAR coherence variable using the DEMs ASTER, PALSAR RTC, Topo-map, and SRTM. Then, a multiInSAR analysis gave displacement velocities in the LOS direction between -10 and 10 mm/year. With the dual-PolSAR analysis (Sentinel-1), VH and VV C-band polarised radar energy emitted median values of backscatters, for landslides, about of -14.5 dB for VH polarisation and -8.5 dB for VV polarisation. Also, L-band fully polarimetric NASA-UAVSAR data allowed to nd the mechanism of dispersion of CGS landslide inventory: 39% for surface scattering, 46.4% for volume dispersion, and 14.6% for double-bounce scattering. The optical remote sensing provided NDVI composites derived from Landsat series between 2012 and 2016, showing that NDVI values between 0.40 and 0.70 had a high correlation to landslides. In summary, we found the highest categories related to landslides by Weight of Evidence method (WofE) for each spaceborne technique applied. Finally, these results were merged to generate the landslide detection model by using the supervised machine learning method of Random Forest. By taking training and test samples, the precision of the detection model was of about 70% for the rotational and translational types.Los deslizamientos son una amenaza natural que causa p茅rdidas humanas, da帽os a la infraestructura y degradaci贸n del suelo. Una evaluaci贸n cuantitativa de su presencia se requiere mediante la detecci贸n y el reconocimiento de potenciales 谩reas inestables. Esta investigaci贸n tuvo como alcance desarrollar un m茅todo soportado en m茅todos semi-autom谩ticos para detectar potenciales movimientos en masa a escala regional. Cinco t茅cnicas fueron estudiadas: Morfometr铆a, Interferometr铆a radar, Interferometr铆a con Persistent Scatterers, Polarimetr铆a radar y composiciones del NDVI con los sat茅lites Landsat 5, Landsat 7 y Landsat 8. El caso de estudio se seleccion贸 dentro de la regi贸n intermedia al este del departamento del Cauca, la cual se caracteriza por terreno monta帽oso y la presencia de inestabilidades de la pendiente oficialmente registrados en el servicio SIMMA del Servicio Geol贸gico Colombiano. Este inventario revel贸 que el tipo de movimiento deslizamiento ocurri贸 con una frecuencia relativa de 77.4%, caidos con el 16.5% de los casos y reptaciones con 3%, flujos con 2.6% y propagaci贸n lateral con 0.43%. Como resultado, se obtuvo las variables morfom茅tricas: pendiente, convergencia, 铆ndice topogr谩fico de humedad y forma del terreno altamente asociados con los deslizamientos. El efecto de un DEM en el procesamiento del m茅todo InSAR fue similar para la variable coherencia usando los DEMs: ASTER, PAlSAR RTC, Topo-map y SRTM. Un an谩lisis Multi-InSAR estim贸 velocidades de desplazamiento en direcci贸n de vista del radar entre -10 y 10 mm/a帽o. El an谩lisis de polarimetr铆a dual del Sentinel-1 arroj贸 valores de retrodispersi贸n promedio de -14.5 dB en la banda VH y -8.5dB en la banda VV. Las cuatro polarimetr铆as del sensor a茅reo UAVSAR permiti贸 caracterizar el mecanismo de dispersi贸n del Inventario de Deslizamiento as铆: 39% en el mecanismo de superficie, 46.4% en el mecanismo de volumen y 14.6% en el mecanismo de doble rebote. La informaci贸n generada en el rango 贸ptico permiti贸 obtener composiciones de NDVI derivados de la plataforma Landsat entre los a帽os 2012 y 2016, mostrando que el rango entre 0.4 y 0.7 tuvieron una alta asociaci贸n con los deslizamientos. En esta investigaci贸n se determinaron las categor铆as de las variables de Teledetecci贸n m谩s altamente relacionadas con los movimientos en masa mediante el m茅todo de Pesos de Evidencias (WofE). Finalmente, estos resultados se fusionaron para generar el modelo de detecci贸n de deslizamientos usando el m茅todo supervisado de aprendizaje de m谩quina Random Forest. Tomando muestras aleatorias para entrenar y validar el modelo en una proporci贸n 70:30, el modelo de detecci贸n, especialmente los movimientos de tipo rotacional y traslacional fueron clasificados con una tasa general de 茅xito del 70%.Ministerio de CienciasConvocatoria 647 de 2014Research line: Geotechnics and Geoenvironmental HazardDoctorad

    Comparison between laparoscopic versus open appendectomy in a pediatric population

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    La apendicitis aguda es la patolog铆a quir煤rgica m谩s frecuente en la poblaci贸n pedi谩trica. Existe a煤n controversia en cuanto a algunos aspectos de la laparoscopia al compararla con la cirugia abierta para el tratamiento de esta patologia en pacientes pedi谩tricos. Es en el marco de esta discusi贸n que surge la necesidad de investigar en el servicio de Cirug铆a Pedi谩trica del Hospital Militar Central en el abordaje m铆nimamente invasivo de la apendicectom铆a y comprarlos con la cirug铆a convencional con el fin de evaluar nuestros resultados con respecto a otras series reportadas en la literatura, para contribuir a la generaci贸n de conocimiento en esta 谩rea.ningunoAcute appendicitis is the most frequent surgical disease in children. There has been a lot of controversy regarding laparoscopy when compared with open surgery for the treatment of appendicitis in children. Because of this, we decided to review the results of minimally invasive surgery for appendicitis in children treated at the pediatric surgical department at Hospital Militar Central in Bogota, Colombia, and compare them with the results of open surgery and other series reported in the literature

    Utilizaci贸n y eficacia de la pierna no dominante en la ejecuci贸n del remate de los jugadores de la primera C del Deportivo Pereira a帽o 2008

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    Semanalmente se pierden cientos de opciones de remate en el f煤tbol profesional a nivel mundial, debido a la poca utilizaci贸n de la pierna no dominante. Adem谩s, es de notar, el pobre 铆ndice de utilizaci贸n y eficacia de dicho miembro. Actualmente, este deporte exige un alto grado de precisi贸n con ambas piernas en el momento de resolver cualquier problema de juego. Adem谩s, es importante conocer la frecuencia con la que cada jugador seg煤n su puesto espec铆fico realiza un remate, con el fin de elaborar entrenamientos m谩s espec铆ficos para cada uno con relaci贸n a este gesto t茅cnico. El presente estudio estar谩 enfocado hacia la evaluaci贸n mediante observaci贸n indirecta del grado de utilizaci贸n y eficacia en la ejecuci贸n del remate con la pierna no dominante en los jugadores del equipo de la primera C del Deportivo Pereira. Para esta investigaci贸n se realiz贸 una grabaci贸n en video de diez partidos en competencia, los cuales Fueron analizados posteriormente llenando una planilla de observaci贸n con el fin de medir lo anteriormente planteado. Los datos obtenidos fueron vaciados en una plantilla de Excel donde se realizaron laS gr谩ficas respectivas. De 130 remates analizados, el 74% se realizaron con la pierna dominante y el 26% fueron ejecutados con la pierna no dominante. La contundencia de la utilizaci贸n de la pierna dominante sobre la no dominante es clara. Corrobor谩ndose as铆 la poca predisposici贸n psicomotriz, cuando se trata de resolver situaciones reales de juego con su pierna no dominante

    Semiolog铆a Radiol贸gica en Patolog铆a Cerebral de Emergencia: Radiological semiology in emergency brain pathology

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    Radiology is a great tool in the diagnosis of encephalic pathologies, especially in situations of neurological urgency and emergency, to rule out the presence of a specific pathology, and to definite the location and size of the lesion, or clarify an initial uncertain diagnosis. In this way, the knowledge of its main signs, findings and characteristics is important to perform an adequate examination, because it facilitates the description of the images obtained with greater speed and precision allowing an optimal and immediate labor of the treating doctor in favor of the patient. Therefore, this article presents a brief review of the representative radiological semiology obtained in the medical literature, where the references were bibliographies and researches, which is convenient to localize the signs that could exist as soon as the examination was obtained, for the future therapeutic of the patient, such as the possibility of extension in the radiology exam or suggestion by the medical technologist of radiology in coordination with the requesting physician to guarantee the patient's care effective.La radiolog铆a es una gran herramienta en el diagn贸stico de patolog铆as encef谩licas, especialmente en situaciones de urgencia y emergencia neurol贸gicas, para descartar la presencia de una patolog铆a espec铆fica, y definir la localizaci贸n y tama帽o de la lesi贸n, o esclarecer un diagn贸stico inicial incierto. De esa forma, el conocimiento de sus principales signos, hallazgos y caracter铆sticas es importante para realizar un examen adecuado, porque esto facilita la descripci贸n de las im谩genes obtenidas con una mayor rapidez y precisi贸n permitiendo una labor 贸ptima e inmediata del m茅dico tratante en favor del paciente. Por ello, este art铆culo presenta una breve revisi贸n de la semiolog铆a radiol贸gica representativa obtenida en la literatura m茅dica, donde las referencias fueron bibliograf铆as e investigaciones, lo cual resulta conveniente para ubicar los signos que pudiese existir apenas fue obtenido el examen, para la futura terap茅utica del paciente, as铆 como la posibilidad de ampliaci贸n en el examen radiol贸gico o sugerencia del tecn贸logo m茅dico de radiolog铆a en coordinaci贸n con el m茅dico solicitante para garantizar la atenci贸n efectiva del paciente

    Indagando sobre la Comunidad Andina

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    La Comunidad Andina est谩 conformada por Bolivia, Colombia, Ecuador, Per煤 y Venezuela. Desde su creaci贸n en 1969, ha estado sujeta a diversos cambios y transformaciones, pasando a su vez por 茅pocas de crisis como la sucedida entre 1979-1987, a la de total estancamiento entre 1987-1989 y luego de recuperaci贸n gracias al modelo de apertura econ贸mica. As铆, en 1985, Bolivia fue el primer pa铆s en aplicar el modelo de liberaci贸n comercial, le siguieron Colombia, Ecuador y Venezuela en 1989 y Per煤 en 1990

    Comparative analysis of order batching and routing problem in the picking regarding classical HVRP (heterogeneous vehicle routing problem)

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    Este art铆culo tiene como objetivo comparar la conformaci贸n de lotes con ruteo, en la preparaci贸n de pedidos respecto al problema HVRP (Heterogeneous Vehicle Routing Problem) bas谩ndose en la utilizaci贸n de una metodolog铆a de la revisi贸n sistem谩tica de la literatura. Del an谩lisis comparativo se identifica la necesidad de realizar modificaciones radicales e incluir nuevos componentes al problema HVRP, para modelar la conformaci贸n de lotes con ruteo de m铆nimo tiempo, en la preparaci贸n de pedidos, considerando K equipos de manejo de materiales (EMM) heterog茅neos, n productos, m posiciones de almacenamiento, la disponibilidad del inventario y dem谩s restricciones asociadas a la operaci贸n.This paper aims to compare the order batching and routing problem(OBRP) regarding heterogeneous vehicle routing problem (HVRP), in order to identify whether there are any differences and similarities between these ones. The OBRP consist in generating product groups, which are collected from storage locations using material specific handling equipment. Each product group(or batch) is matched to a route, which states the sequences to pick the products in the shortest time possible. On the other hand, HVRP is a variant of the Vehicle Routing Problem(VRP), in which customers are served by a heterogeneous fleet of vehicles with various capacities, in order to delivery products in a distribution network at the lowest possible cost. Additionally, in the related literature were not identified HVRP papers that tackled order batching and routing problem (OBRP), but they were focused primarily in transportation and distribution process. Therefore, it was detected a gap in the state of the art. The comparation analysis was developed using a variation of the methodology called Systematic Literature Review (SLR) , which was based on analysis of papers. This methodology was implemented eight stages, the most important of which are as follows: i) formulating the research questions and evaluation criteria (stage 2), ii) inclusion and exclusion criteria (stage 3), iii) results of systematic review (stage 6), iv) comparative analysis between OBRP and HVRP based on set evaluation criteria (stage 7) and v) conclusions and research opportunities (stage 8). The main findings of this paper were as follow: First, order batching was not modeled in HVRP, hence relevance of this gap. Second, in order batching and routing problem is necessary to represent K heterogeneous MHE with different speed travels, load capacities and lift heights. In HVRP papers the heterogeneity is only caused by vehicles in different load capacities. Third, a constraint among n products, m storage locations and K heterogeneous EMH should be implemented to ensure the feasibility of solutions of OBRP. This constraint is raised, since any MHE are not able to pick some products from storage locations, due to theirs technical characteristics. In addition, none of HVRP papers represented this constraint. Fourth, setup time and handling time were not modeled in reviewed HVRP papers, since these times were not as significant in transportation and distribution routes. Therefore, these times should be included in HVRP to represent OBRP. Fifth, available of inventory were not considered in HVRP papers, since this condition was not important in the modeled process. It should be noted that this condition is critical in OBRP, since only can be picked products with available inventory in Distribution Centre (DC). Based on findings, it was detected a significant gap in the state of the art related to the formulation and solution a minimum time OBRP considering n products, m storage locations and K heterogeneous MHE and described constraint. Therefore, this approach, not only it will fill this gap, but also contribute to knowledge in OBRP. In addition, this paper it will be one of the first to analyze HVRP in warehouse and DC

    Consumer choice and local network effects in the colombian mobile telecommunications market

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    El objetivo de este art铆culo es analizar el grado de los efectos de red en el mercado m贸vil de telecomunicaciones en Colombia, e identificar otros determinantes de la elecci贸n del consumidor bas谩ndose en una encuesta de usos y h谩bitos realizada por el Centro Nacional de Consultor铆a para la Comisi贸n de Regulaci贸n de Comunicaciones en el a帽o 2016. A partir de esa encuesta se realiz贸 este estudio que muestra que no existen diferencias regionales en la adopci贸n de operadores en Colombia, y que el atractivo de los diferentes operadores depende del tama帽o total del operador al cual se quiera suscribir el usuario. Este hallazgo significa que el mercado relevante se debe definir a nivel nacional y que las estrategias de precios de los operadores deben ser de car谩cter nacional y no regional. Tambi茅n se encuentra que en la elecci贸n de operador son determinantes claves el sexo de las personas, la edad, el estrato, el gasto mensual en servicios m贸viles, el tipo de plan y el n煤mero de llamadas que se realizan. Por 煤ltimo, los usuarios prefieren al operador que les brinde la mayor experiencia por lo cual es un determinante clave a trabajar por parte de los operadores de servicios m贸viles en Colombia.The objective of this article is to analyze the degree of network effects in the mobile telecommunications market in Colombia, and identify other determinants of consumer choice based on a survey of uses and habits carried out by the National Consulting Center for the Commission of Regulation of Communications in 2016. Based on this survey, this study was conducted which shows that there are no regional differences in the adoption of operators in Colombia, and that the attractiveness of the different operators depends on the total size of the operator to which the user wishes to subscribe. This finding means that consumers are not likely to be affected by other people's choices within their local area but rather by the overall size of the network. The relevant market must be defined at the national level and the pricing strategies of the operators must be national and not regional. It is also found that in the choice of operator key factors are gender, the age, the stratum, the monthly expenditure on mobile services, the type of plan and the number of calls made. Finally, users prefer the operator that offers them the greatest experience, which is why it is a key determinant to work for operators of mobile services in Colombia.Universidad Pablo de Olavid
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