Planning Rapid Transit Networks

Rapid transit construction projects are major endeavours that require long-term planning by several players, including politicians, urban planners, engineers, management consultants, and citizen groups. Traditionally, operations research methods have not played a major role at the planning level but several tools developed in recent years can assist the decision process and help produce tentative network designs that can be submitted to the planners for further evaluation. This article reviews some indices for the quality of a rapid transit network, as well as mathematical models and heuristics that can be used to design networks.Canadian Natural Sciences and Engineering Research Council 39682-10Ministerio de Ciencia e Innovación MTM 2009-14243Junta de Andalucía P09-TEP-502

A maximum trip covering location problem with an alternative mode of transportation on tree networks and segments

In this paper the following facility location problem in a mixed planarnetwork space is considered: We assume that traveling along a given network is faster than traveling within the plane according to the Euclidean distance. A pair of points (Ai,Aj ) is called covered if the time to access the network from Ai plus the time for traveling along the network plus the time for reaching Aj is lower than, or equal to, a given acceptance level related to the travel time without using the network. The objective is to find facilities (i.e. entry and exit points) on the network that maximize the number of covered pairs. We present a reformulation of the problem using convex covering sets and use this formulation to derive a finite dominating set and an algorithm for locating two facilities on a tree network. Moreover, we adapt a geometric branch and bound approach to the discrete nature of the problem and suggest a procedure for locating more than two facilities on a single line, which is evaluated numerically.Future and Emerging Technologies Unit of EC (IST priority—6th FP) FP6-021235-2 (project ARRIVAL)Ministerio de Educación, Ciencia e Innovación (Spain)/FEDER MTM2009-14243Junta de Andalucía (Spain)/FEDER P09-TEP-5022Junta de Andalucía (Spain)/FEDER FQM-584

Computational study of a novel Knudsen pump design exploiting drilling and 3D printing techniques in low thermal conductivity materials

International audienc

Adsorption of azo-dye Orange II from aqueous solutions using a metal-organic framework material: Iron- benzenetricarboxylate

A Metal-Organic Framework (MOF), iron-benzenetricarboxylate (Fe(BTC)), has been studied for the adsorptive removal of azo-dye Orange II from aqueous solutions, where the effect of various parameters was tested and isotherm and kinetic models were suggested. The adsorption capacities of Fe(BTC) were much higher than those of an activated carbon. The experimental data can be best described by the Langmuir isotherm model (R2 > 0.997) and revealed the ability of Fe(BTC) to adsorb 435 mg of Orange II per gram of adsorbent at the optimal conditions. The kinetics of Orange II adsorption followed a pseudo-second-order kinetic model, indicating the coexistence of physisorption and chemisorption, with intra-particle diffusion being the rate controlling step. The thermodynamic study revealed that the adsorption of Orange II was feasible, spontaneous and exothermic process (-25.53 kJ·mol-1). The high recovery of the dye showed that Fe(BTC) can be employed as an effective and reusable adsorbent for the removal of Orange II from aqueous solutions and showed the economic interest of this adsorbent material for environmental purposes. © 2014 by the authors.The authors thank Autonomous Metropolitan University for its financial support to the project “Synthesis, modification and application of porous solid materials to sorption phenomena and catalysis”. Elizabeth Rojas-Garcia and Ricardo López-Medina thank CONACYT for their repatriation program fellowships. We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)Peer Reviewe

Estudio de la degradación fotocatalítica del colorante Negro 5, con el sistema titania industrial-alcóxido

En este estudio se prepararon catalizadores con titania con relaciones molares de TiO₂ industrial/alcóxido = 1, 5, 20, 100 y fueron calcinados a 450°C. Los catalizadores fueron estudiados con la difracción de rayos X, espectroscopia Raman y UV de sólidos. Se probaron las propiedades fotocatalíticas en la degradación del colorante Reactivo Negro 5, usando UV y luz visible. Se puede ver, que con luz UV se obtiene mejor actividad conforme se aumenta la cantidad de alcóxido, pero con luz visible disminuyó la actividad de degradación con el aumento del alcóxido.In this study, titania catalysts were prepared with molar ratios of industrial TiO₂/alkoxide = 1, 5, 20, 100 and calcined at 450°C. The catalysts were studied with X-ray diffraction, Raman and UV spectroscopy of solids. The photocatalytic properties on the degradation of Reactive Black 5 dye were tested using UV and visible light. It can be seen that with UV light better activity is obtained as the amount of alkoxide increases, but with visible light the degradation activity decreased with the increase in alkoxide

Degradación sono-fotocatalítica de orange II usando Fe₂O₃-TiO₂

Fe₂O₃-TiO₂ (1% de Fe) y muestras de TiO₂ puro (como referencia) fueron sintetizados por el método sol-gel. Los catalizadores Fe₂O₃-TiO₂ se prepararon para obtener un contenido de 1% de hierro. El TiO₂ sintetizado fue mezclado y molido con nanopartículas Fe₂O₃. Se determinó su estructura cristalográfica, parámetros de red y tamaño de partícula por difracción de rayos X. El área específica y diámetro de poro fueron determinados por el método BET (N₂ adsorción). Además, se realizaron estudios de degradación mediante reacciones fotocatalíticas y sono-fotocatalíticas, en la degradación del colorante Orange II (ultrasonido 250, 500 y 1000 kHz). Los materiales calcinados mostraron ser nanopartículas mesoporosas de TiO₂ en fase anatasa, con excelentes propiedades sonofotocatalíticas. La mejor actividad sono-fotocatalítica resultante fue mediante el uso de ultrasonido de 500 KHz. La longitud de onda de la fuente de luz no fue importante en las reacciones fotocatalíticas.Fe₂O₃-TiO₂ (1% Fe) samples and pure TiO₂ (as reference) were synthesized by the sol gel method. The Fe₂O₃-TiO₂ catalysts were prepared to obtain a content of 1% of iron. The synthesized TiO₂ was mixed and ground with Fe₂O₃ nanoparticles. Their crystallographic structure, lattice parameters and particle size were determined by X-ray diffraction. The specific area and pore diameter was studied by BET method (N2 adsorption). In addition, degradation studies using Orange II dye sono-photocatalysis were performed (ultrasound 250, 500 and 1000 kHz). The calcined materials showed TiO₂ nanoparticles in anatase phase and the mesoporous structures showed excellent sono-photocatalytic properties. Best sono-photocatalytic activity resulted with the use of ultrasound to 500 KHz. The wavelength of the light source was not important in photocatalytic reactions

Nanoestructuras de carbono en redes metal-orgánicas para la reducción fotocatalítica de CO₂ a combustibles

En el presente trabajo se plantea la conversión del CO₂ a combustibles mediante el uso de los fotocatalizadores, como los nanotubos de carbono incorporados a materiales híbridos metal-orgánicos como es el MOF Fe-BTC. Se logró la síntesis de materiales compósitos de Fe-BTC/CNT encontrando que 1.5% de CNT es la cantidad óptima, que los materiales resultaron tener buena actividad fotocatalítica produciendo biocombustibles como etanol y metanol, pudiendo competir con la producción reportada en la literatura aplicando la reducción fotocatalítica de CO₂.In the present work, the conversion of CO₂ to fuels was proposed by the use of photocatalysts, such as carbon nanotubes incorporated into metal-organic hybrid materials such as the MOF Fe-BTC. In this project the synthesis of Fe-BTC/CNT composite materials was achieved, finding that 1.5% of CNT is the optimum quantity, that the materials obtained have good photocatalytic activity producing biofuels such as ethanol and methanol, being able to compete with the production reported in the literature applying the photocatalytic reduction of CO

Síntesis y caracterización de ZnTiO₃ hexagonal mediante el método sol-gel

Se prepararon titanatos de zinc (ZnTiO₃) con alta pureza mediante el método sol-gel y posterior calcinación a diferentes temperaturas. La caracterización se realizó mediante análisis térmico diferencial (DTA, del inglés), termogravimétrico (TGA), difracción de rayos X (DRX) y microscopia electrónica de barrido (MEB). Se estudió el efecto de la cantidad de agua utilizada en la síntesis y la temperatura de calcinación sobre las propiedades estructurales y morfológicas.Zinc titanates (ZnTiO₃) were prepared with high purity by the sol-gel method and subsequent calcination at different temperatures. The characterization was carried out by differential thermal analysis (DTA), thermogravimetric (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of the amount of water used in the synthesis and the calcination temperature on the structural and morphological properties of zinc titanates were mainly studied

Degradación fotocatalítica de Orange II y Negro reactivo 5 mediante Fe-óxido de grafeno/TiO₂

En este trabajo se estudió la síntesis, caracterización y evaluación fotocatalítica de materiales a base óxido de titanio (TiO₂) impregnado con hierro y óxido de grafeno. Se preparó un material Fe- TiO₂, al cual se le impregnó óxido de grafeno (GO). La caracterización del fotocatalizador se realizó mediante difracción de rayos X (XRD) y UV-Vis reflectancia difusa (DR). La actividad fotocatalítica se evaluó con la degradación de los colorantes Orange II y Negro 5. Los materiales presentaron la fase anatasa y la banda prohibida disminuyó con el contenido de hierro-OG. La presencia de de hierro-(oxido de grafeno) permitieron la degradación de colorantes mediante el uso de luz visible.In this work we studied the synthesis, characterization and photocatalytic evaluation of materials based on titanium oxide (TiO₂) impregnated with iron and graphene oxide. A Fe- TiO₂ material was prepared, which was impregnated with graphene oxide (OG). The characterization of the photocatalyst was carried out by X-ray diffraction (XRD) and UV-Vis diffuse reflectance (DR). The photocatalytic activity was evaluated with the degradation of the Orange II and Black 5 dyes. The materials presented the anatase phase and the band gap decreased with the iron-OG content. The presence of iron-graphene oxide allowed the degradation of dyes by the use ofvisible light