Search

The trend in the development of maritime and river propulsion systems is to make a transition from hydrocarbon to more environmentally friendly solutions. This contributes positively to the solution of the problems identified by the International Maritime Organization (IMO) regarding the high emissions of polluting gases emitted by maritime transportation. Currently, there is a wide variety of systems available due to the development of mobility technologies focused on decarbonization. This paper presents an analysis of technological alternatives for boats with electromobility applications and propulsion systems in the waterway field. First, a description of the operation of boats with electric motors, the different energy sources, and the alternative propulsion options is presented. Then, the electromobility technologies are characterized, analyzing the different configurations between the power source and the propulsion system. The results show a comparative table of technologies and their advantages and disadvantages. In addition, the most environmentally friendly technologies present significant challenges for large-scale implementation due to their recent development. In the short term, hybrid systems technologies present advantages over the others, as current systems are available, with the addition of equipment with higher efficiency and lower environmental impact.

Copyright of Scientia et Technica is the property of Scientia et Technica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Masa Stork Company recognized in the hydrocarbons sector in Colombia, in a power generation project saw the need to use 2-inch tubing to transport wastewater in the cooling of motor-generators, presenting the problem of fracture in the welding when they are put into operation. When stainless steels are heated in a temperature range of 500 ° C to 700 ° C, the carbon-containing the steel reacts with the chromium to form chromium carbides that do not have the same characteristics as the alloyed chromium. These reactions deplete the steel and reduce its properties in the heated zone. This investigation focused in the determination of the influence of the temperature in the ZAT of a welding in stainless steel AISI 316, under GTAW process, welded with ER316 electrode when subjected to pre-heating temperature before welding and its behavior before heat treatment; and determining that in the welding a low contribution of heat must be taken into account, distributing the heat in a balanced way so that it is distributed in the piece as symmetrically as possible. In addition, it must be ensured that the level of embrittlement is as low as possible, thus making the Zone Affected by heat more narrow.

La empresa Masa Stork, reconocida en el sector de hidrocarburos en Colombia, se vio en la necesidad de utilizar en un proyecto de generación de energía tubería de 2 pulgadas para transporte de aguas residuales en la refrigeración de moto-generadoras pero posteriormente se presentó un problema de fractura en la soldadura cuando estas se pusieron en funcionamiento. Cuando los aceros inoxidables son calentados en un rango de temperatura de 500°C a 700°C, el carbono que contiene el acero reacciona con el cromo y forma carburos de cromo que no tienen las mismas características del cromo aleado. Estas reacciones empobrecen el acero y hacen que disminuyan sus propiedades en la zona calentada. Esta investigación se enfocó en la determinación de la influencia de la temperatura en la Zona Afectada Termodinámicamente (ZAT) de una soldadura en acero inoxidable AISI 316, bajo proceso GTAW, soldado con electrodo ER316 al ser sometido a temperatura de precalentamiento antes de la soldadura y su comportamiento ante tratamiento térmico. Se determinó que en el soldeo debe tenerse en cuenta una baja aportación de calor, distribuyendo el calor en forma equilibrada para que este sea repartido en la pieza de la forma más simétricamente posible. Además, se debe procurar que el nivel de embriamiento sea lo más bajo posible, así se consigue que la ZAT sea más estrecha.

Presentamos el caso de un paciente de sexo masculino, de 26 años de edad, con compromiso subagudo de la fuerza muscular de los miembros inferiores y retención urinaria. Se documentó la presencia de un tuberculoma intramedular para el que recibió tratamiento antituberculoso y corticosteroides, obteniéndose resolución total de los síntomas. Al final se hace una corta revisión de la literatura científica.We present the case of a 26 year old male patient, with a subacute compromise of muscle strength in his lower limbs and urinary retention. The presence of an intramedullary tuberculoma was documented. The patient received corticosteroids and anti-tuberculous therapy, with a total resolution of the symptoms. A short a literature review is also included.