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Appropriate interaction between pantograph and catenary is imperative for smooth operation of electric trains. Changing heights of overhead lines to accommodate level crossings, overbridges, and tunnels pose significant challenges in maintaining consistent current collection performance as the pantograph aerodynamic profile, and thus aerodynamic load changes significantly with operational height. This research aims to analyse the global flow characteristics and aerodynamic forces acting on individual components of an HSX pantograph operating in different configurations and orientations, such that the results can be combined with multibody simulations to obtain accurate dynamic insight into contact forces. Specifically, computational fluid dynamics simulations are used to investigate the pantograph component loads in a representative setting, such as that of the recessed cavity on a Class 800 train. From an aerodynamic perspective, this study indicates that the total drag force acting on non-fixed components of the pantograph is larger for the knuckle-leading orientation rather than the knuckle-trailing, although the difference between the two is found to reduce with increasing pantograph extension. Combining the aerodynamic loads acting on individual components with multibody tools allows for realistic dynamic insight into the pantograph behaviour. The results obtained show how considering aerodynamic forces enhance the realism of the models, leading to behaviour of the pantograph–catenary contact forces closely matching that seen in experimental tests.

The interaction between the rolling stock and the infrastructure plays a crucial role in railway vehicle dynamics. The standard approach consists of using a multibody formulation to model the railway vehicles running on simplified tracks. The track model can be rigid, if it comprises only a geometric description of the rail; semi-rigid, if it considers an elastic foundation underneath the rail; or a moving track model, if it comprises a track section underneath each wheelset traveling with the same speed of the vehicle. Despite their computational inexpensiveness, these approaches do not provide a complete representation of track flexibility and disregard coupling effects with the vehicle and among the track components. This work proposes a methodology to automatically generate finite element models of railway tracks comprising its relevant flexible components, i.e., rails, pads, fastening systems, sleepers, and ballast or slab. The finite element mesh is generated based on a parametric description of the track that allows an accurate description of its geometry, including curvature, cross-level, grade, and irregularities. The methodology is demonstrated with a case study in which a track with a complex geometry is loaded with two different approaches. The first approach prescribes moving loads, which is a typical approach used to design or analyze the infrastructure. The second approach applies loads retrieved from the dynamic analysis of a complete vehicle. The results show the benefits of this method and reveal that prescribed loading underestimates the forces resulting from the vehicle dynamics, which is an important issue on curved sections.

Railway vehicle homologation with respect to running dynamics is addressed via dedicated norms that require the knowledge of the accelerations and wheel–rail contact forces obtained from experimental computational testing. Multibody dynamics allows the modelling of railway vehicles and their simulation on realistic operations conditions. However, the representativeness of the multibody models, and the results of their use in railway dynamics are greatly influenced by the modelling assumptions and their ability to represent the operational conditions. In this paper, two alternative multibody models of a railway vehicle are presented and simulated in a realistic railway track scenarios to appraise the consequences of different modelling assumptions on the railway dynamic analysis outcome. A vehicle–track interaction compatibility analysis is performed afterwards according to norm EN 14363. The analysis consists of two stages: the use of a simplified method, described in the norm for the identification of the different performance indexes from the railway vehicle dynamic analysis outcome; and the visual inspection of the vehicle motion with respect to the track via dedicated visualization tools. The results of the virtual vehicle homologation tests are presented and discussed in face of the modelling assumptions used, being significant differences identified between the railway vehicle modelled with cylindrical joints with clearances or with equivalent force elements. It is also concluded that the use of clearance joints prevents the need to use modelling assumptions on the equivalent force elements that have limited or no physical meaning, thus reducing the number of modelling parameters for which a high level of abstraction has to be exercised.

In the oil industry, pipelines (circular ducts) are widely used for the transportation of oil and yours derived. Because of their advantages, such as low operating cost and increased safety during transportation, pipelines have become indispensable for transporting oil in large quantities and for long distances. As an alternative to this problem, the transport of oil and water can be accomplished using ducts with an elliptical cross-section. Thus, this work has the objective of studying the flow of oil and water in cylindrical ducts with an elliptical cross-section by using the Ansys CFX software. Results of the velocity, pressure and volumetric fraction distributions of the oil and water phases are presented and analyzed. By applying the same inlet velocity to oil and water, revealed that the elliptical duct, with aspect ratio equal to 5.0, has a pressure drop less (84.2%) than the pressure drop obtained for one duct of circular cross-section (aspect ratio equal to 1.0).

One of the main challenges related to the oil industry is the conscious disposal of effluents from the stages of oil exploration and production. The treatment of the water produced originated these processes has become a challenge for the sector. The membrane filtration technique emerges as an important tool in the treatment of these oily waters, due to their good characteristics, such as uniformity in permeate quality and long shelf life. In this work, a 2D mathematical model was developed, using computational fluid dynamics (CFD) as tool for the evaluation of the water-oil separation process in a tubular ceramic membrane. Linear momentum, energy, and mass conservation equations were used, which were solved using the commercial package ANSYS CFX® 15. The results obtained demonstrate that the developed model was able to predict the behavior of the water/oil separation process through the membrane, evidencing the influence of the oil particle size under the formation of the polarization layer by concentration, as well as, allowed to verify the importance of the temperature and the retention index of the solute under the permeation velocity and system performance.

Hydrocyclones are equipment that offer various advantages and have been the subject of studying for many researches related to separation processes of gas-solid, solid-liquid, and liquid-liquid mixtures. The purpose of this work is to study the oil-water separation process in a hydrocyclone by Computational Fluid Dynamics (CFD). Results of the pressure, velocity and volume fraction fields inside the device are presented and analyzed. It was possible to conclude that the proposed mathematical model was able to predict separation performance and the three-dimensional behavior of the phases flow analyzed (water/oil) in the hydrocyclone.

Oil reservoirs are porous and permeable rocks that allow the hydrocarbon accumulation. Reservoir simulations are necessary to obtain the best fluid flow conditions in the porous medium and increase oil recovery capacity. The aim of this paper was to study the influence of the absolute rock permeability on the oil recovery of a complex geometry oil reservoir, using water injection with the black oil model. Numerical simulations in boundary-fitted coordinates were performed in a two-dimensional and irregularly shaped reservoir. Finite volume method was used to solve the governing equations and two inverted five-spot meshes were set in parallel for a total injection time of 30 years. Results of injected porous volume per recovered oil volume, the water cut charts and the water saturations maps showed that the lower porous medium permeability increased the oil recovery, once the permeability intensified fingers and early breakthrough, which leads to high water production rates and consequent reduction of the waterflooding efficiency.

Innovative technologies are needed to attend the increasingly strict requirements for produced water treatment, since most of the separation processes are limited to particles larger than 10 µm. Separation processes using ceramic membranes are attracting great interest from academic and industrial community. Nevertheless, few studies, especially numerical, regarding the inorganic membrane’s application for the polluted water separation have been reported. In the present work, therefore, a study of fluid-flow dynamics for a laminar regime in porous tubes (tubular porous ceramic membrane) has been performed. The mass, momentum and mass transport conservation equations were solved with the aid of a structured mesh using ANSYS CFX commercial package. The velocity of local permeation was determined using the resistance in series model. The specific resistance of the polarized layer was obtained by Carman-Kozeny equation. The numerical results were evaluated and compared with the results available in the literature, where by a good agreement with each other was found. The numerical results, obtained by the proposed shell and tubular membrane separation module, indicate that there is facilitation of mass transfer and hence a reduction in the thickness of the polarized boundary layer occurs.

Background: Accumulating evidence indicates that mangiferin (MGF), a natural xanthone, by virtue of its antioxidant and anti-inflammatory properties is neuroprotective. Here we sought to verify the cytoprotective role of MGF on cultured rat primary mesen-cephalic cells exposed to 6-hydroxydopamine (6-OHDA) in vitro, and the MGFs anti-inflammatory potential in mouse model of ketamine-induced schizophrenia in vivo. Methods: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-assay was performed to measure cell viability in mesen-cephalic cell cultures exposed to neurotoxin (6-OHDA, 40 µM). Schizophrenia was induced in mice by ketamine (50 mg/kg, ip, twice a day, for 7 days). The treatment effects of MGF (50 mg/kg, po, for 7 days) were verified on locomotor behavioral changes in open-field test, and on the oxidant stress-related increase in lipid-peroxidation (malondialdehyde) and interleukin-6 (IL-6) levels in brain tissues. Results: MGF (10-100 µM) produced no per seeffect on cell viability as measured by MTT assay, but significantly prevented the 6-OHDA-induced cell death in a concentration-dependent manner. Acridine orange/ethidium bromide (AO/EtBr) staining confirmed the absence of 6-OHDA-induced morphological changes characteristic of apoptosis/necrosis. In open-field test, ketamine-induced impaired locomotor activity and behavioral changes such as grooming and stereotyped but not rearing were effectively ameliorated by MGF pretreatment. Also, ketamine-associated increase in brain tissue levels of IL-6 and MDA were significantly lowered in MGF-pretreated mice. Conclusion: Mangiferin has a neurocytoprotective role related, at least in part, to an antioxidant and anti-inflammatory mechanism, which could be explored for more effective therapies of schizophrenia and other neurodegenerative diseases.

We have estimated the incidence and molecular basis of α-thal-assemia in a Portuguese population, mostly from the Greater Lisbon area. In a group of 100 consecutive cord blood samples, the gene frequency of the rightward deletion (-α3.7) was 0.035, and the leftward deletion (-α4.2) was 0.015. In this group, we have also found four heterozygotes for the triple α-globin gene rearrangement (αααanti3.7 gene frequency 0.020). We have characterized the subtypes of -α3.7 and αααanti3.7 rearrangements. On the whole, these results give an incidence of 10% for deletional a-thalassemia carriers in the studied Portuguese population In a group of 342 subjects presenting β-thalassemia, or Hb S trait, β-thalassemia major, sickle cell disease or low red blood cell indices, the -α3.7, -α4.2, -SEA -MED (αα)MM and αααanti3.7 haplotypes were found in different combinations. Only one nondeletional α-thalassemia determinant (a 5 nucleotide deletion in the α2-globin gene in the second intervening sequence donor site) was detected, which might suggest a low incidence of these defects in the Portuguese population