194 research outputs found
The Jordanian Humanitarian Demining Program: A Model of Optimism and Persistence
Detecting and removing over 300,000 estimated mines in Jordan’s 509 mine fields is a huge but not insurmountable problem. The deliberate clearing process requires courageous patience, a demonstrated quality of Jordan’s highly qualified engineer officers and soldiers. Trained and experienced deminers, outfitted with state-of-the-art protective equipment and using internationally recognized demining techniques and methodologies, form the base of the Royal Corps of Engineers Humanitarian Demining (HD) attack plan. Though many mines are unaccounted for due to erosion, flooding, and accidental detonation, Royal Corps of Engineer HD soldiers have an established perseverance that will prevail
Design of a Distribution Network Using Primal-Dual Decomposition
Amethodtosolvethedesignofadistributionnetworkforbottleddrinkscompanyisintroduced.Thedistributionnetworkproposed includes three stages: manufacturing centers, consolidation centers using cross-docking, and distribution centers. The problem is formulated using a mixed-integer programming model in the deterministic and single period contexts. Because the problem considersseveralelementsineachstage,adirectsolutionisverycomplicated.Formedium-to-largeinstancestheproblemfallsinto large scale. Based on that, a primal-dual decomposition known as cross decomposition is proposed in this paper. This approach allows exploring simultaneously the primal and dual subproblems of the original problem. A comparison of the direct solution withamixed-integerlinealprogrammingsolverversusthecrossdecompositionisshownforseveralrandomlygeneratedinstances. Resultsshowthegoodperformanceofthemethodproposed
Lead time performance in a internet product delivery supply chain with automatic consolidation
Internet sales have increased exponentially in the last decade. Much of the internet sales are of physical products in urban areas that require product delivery transportation with a tight delivery lead time. With this challenge, a new type of transportation services has been developed aiming to cope with a strict control of transportation lead time. In this paper, an internet product delivery service with customer orders that are multi-item as well as single item is simulated. We address specifically the mismatch between supply and demand when retailers for any reason are unable to estimate the configuration of multi-item orders. Three scenarios of demand patterns are simulated (demand as forecasted, lower than forecasted and higher than forecasted) using discrete-event simulation to look at the effect on transportation lead time. Results show the positive effect on the mismatch between demand and resource capacity which is expressed in higher number delayed delivery orders. The excess of capacity in the product delivery supply chain has not a positive impact on delivery time of orders as technically orders are not delivered before the multi-item components are not available. This leads to think that the excess of resources are not an element that add value to customers waiting for their orders.CONACY
Platinum-Bismuth Bimetallic Catalysts: Synthesis, Characterization and Applications
Bimetallic catalysts have been explored and shown to exhibit unique characteristics which are not present in monometallic catalysts. Platinum is well known as an effective catalyst for oxidation and reduction reactions, and it can be made more effective when bismuth is introduced as a promotor. Thus, the effectiveness of the Pt-Bi catalyst was demonstrated in prior work. What is not clear, however, is the mechanism behind the catalyst function; why addition of bismuth to platinum decreases deactivation and increases selectivity, and how effective would the Pt-Bi catalyst be in deoxygenation reactions? In this work, the effectiveness of different variations of the Pt-Bi catalyst was explored for the deoxygenation of guaiacol. Methane was selected as the model reductant. Two Pt-Bi catalysts with different metal ratios were prepared, tested and characterized to reveal the catalyst’s structure. Methods used in characterization included SEM, TEM and BET measurements. Representative catalysts were then tested in a fixed-bed reactor for performance
Posibles efectos de la implantación de la Alta Velocidad Ferroviaria en México: el caso del Tren Rápido de Pasajeros México-Querétaro
191 páginas. MaestrÃa en Planeación y PolÃticas Metropolitanas.El ferrocarril es, sin duda alguna, el modo de transporte que ha desarrollado mayores cambios en los últimos años en el mundo. La alta velocidad ferroviaria (AVF) ha revolucionado el mercado del transporte, su introducción ha conseguido cambiar la imagen de un sistema que se consideraba lento, incómodo y anticuado. Gracias a la nueva oferta de transporte basada en la velocidad, el acceso directo al centro de las ciudades, la puntualidad, la comodidad y, en general, la calidad del servicio, el Tren de Alta Velocidad (TAV) ha conseguido captar viajeros de otros modos de transporte e incluso generar una nueva demanda. Sin embargo, la AVF produce importantes efectos socioeconómicos, ambientales y urbanos en los territorios donde se establece
Multiple-fault detection methodology based on vibration and current analysis applied to bearings in induction motors and gearboxes on the kinematic chain
© 2016 Juan Jose Saucedo-Dorantes et al. Gearboxes and induction motors are important components in industrial applications and their monitoring condition is critical in the industrial sector so as to reduce costs and maintenance downtimes. There are several techniques associated with the fault diagnosis in rotating machinery; however, vibration and stator currents analysis are commonly used due to their proven reliability. Indeed, vibration and current analysis provide fault condition information by means of the fault-related spectral component identification. This work presents a methodology based on vibration and current analysis for the diagnosis of wear in a gearbox and the detection of bearing defect in an induction motor both linked to the same kinematic chain; besides, the location of the fault-related components for analysis is supported by the corresponding theoretical models. The theoretical models are based on calculation of characteristic gearbox and bearings fault frequencies, in order to locate the spectral components of the faults. In this work, the influence of vibrations over the system is observed by performing motor current signal analysis to detect the presence of faults. The obtained results show the feasibility of detecting multiple faults in a kinematic chain, making the proposed methodology suitable to be used in the application of industrial machinery diagnosis.Postprint (published version
Over 10% efficient wide bandgap CIGSe solar cells on transparent substrate with Na predeposition treatment
With the recent rise of new photovoltaic applications, it has become necessary to develop specific optoelectronic properties for thin-film technologies such as Cu(In,Ga)Se2 and to take advantage of their high degree of tunability. The feasibility of efficient wide bandgap absorbers on transparent conductive oxide substrates is, in that context, of critical importance. Using an original approach based on a predeposition sodium treatment, Cu(In,Ga)Se2 absorbers fabricated by sputtering and reactive annealing with a Ga to (Ga + In) content over 0.7 and an optical bandgap above 1.4 eV are deposited on transparent fluorine-doped tin oxide films, with the insertion of an ultrathin MoSe2 layer preserving the contact's ohmicity. Different material characterizations are carried out, and a thorough Raman analysis of the absorber reveals that the sodium pretreatment significantly enhances the Ga incorporation into the chalcopyrite matrix, along with markedly improving the film's morphology and crystalline quality. This translates to a spectacular boost of the photovoltaic performance for the resulting solar cell as compared with a reference device without Na, specifically in the voltage and fill factor. Eventually, an efficiency exceeding 10% is obtained without antireflection coating, a record value bridging the gap with the state of the art on nontransparent substrates.Peer ReviewedPostprint (author's final draft
Biosurfactants: The green generation of speciality chemicals and potential production using Solid-State fermentation (SSF) technology
Smart Monitoring Based on Novelty Detection and Artificial Intelligence Applied to the Condition Assessment of Rotating Machinery in the Industry 4.0
The application of condition monitoring strategies for detecting and assessing unexpected events during the operation of rotating machines is still nowadays the most important equipment used in industrial processes; thus, their appropriate working condition must be ensured, aiming to avoid unexpected breakdowns that could represent important economical loses. In this regard, smart monitoring approaches are currently playing an important role for the condition assessment of industrial machinery. Hence, in this work an application is presented based on a novelty detection approach and artificial intelligence techniques for monitoring and assessing the working condition of gearbox-based machinery used in processes of the Industry 4.0. The main contribution of this work lies in modeling the normal working condition of such gearbox-based industrial process and then identifying the occurrence of faulty conditions under a novelty detection framework
Aplicación del programa Vontron para la simulacion de la desalinizacion de agua salobre mediante osmosis inversa para la obtencion de agua potable
El objetivo fue simular con el software Vontron la desalinización de agua salobre mediante osmosis inversa para obtener agua potable. Se usó una muestra de agua salobre de un pozo en LurÃn, considerando parámetros de campo, enviándose las demás muestras al laboratorio para analizarlas con los parámetros de concentraciones de cloruros, nitratos, sulfato y metales totales y con el informe emitido se pasó a la siguiente etapa. Se ingresaron los datos al programa VONTRON para la simulación, se consideraron parámetros de operación y diseño, se hizo una simulación de diseño de sistema de osmosis inversa para obtener agua potable. Se realizó una matriz de experimentos con los parámetros de operación obteniéndose variables respuestas: flujo de alimentación, flujo de concentrado, presión de alimentación, presión de concentrado, energÃa especÃfica y SÓLIDOS TOTALES DISUELTOS Permeado (Solidos Totales disueltos), extraÃdos de las hojas de resultados del software para ingresar los parámetros de operación y diseño. También se usó el software Minitab 19, ingresando los datos de las hojas de resultados del software Vontron dándose diferentes combinaciones de tratamientos con tablas y gráficas para determinar el mejor tratamiento para diseñar un sistema de osmosis inversa, resultando favorable los parámetros de operación Ni 1, con ellos se podrá diseñar una planta de osmosis inversa y obtener agua potable eficientemente con datos reales según nuestro software comparándolo con el reglamento de calidad del agua
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