Search results for " ferro"

An ANN model to correlate roughness and structural performance in asphalt pavements

2017

Abstract In this paper, using a large database from the Long Term Pavement Performance program, the authors developed an Artificial Neural Network (ANN) to estimate the structural performance of asphalt pavements from roughness data. Considering advantages of modern high-performance survey devices in the acquisition of road pavement functional parameters, it would be of practical significance if the structural state of a pavement could be estimated from its functional conditions. To differentiate various road section conditions, several significant input parameters, related to traffic, weather, and structural aspects, have been included in the analysis. The results are very interesting and …

Propriétés et performances de phosphines ferrocéniques dans le couplage C-O, C-S et C-N : nouvelles méthodologies de synthèse au palladium

2012

Multidentate ligands usually show great activities in low loading organometallic catalysis in palladium. Among these ligands, the use of ferrocenyl polyphosphane ligands give interesting results. Robust palladium-ferrocenyl triphosphane catalytic systems have permitted to obtain biarylamines and aryl-heteroaryl ethers in the presence of low catalytic loadings. DFT studies on catalytic cycle during formation of aryl-heteroaryl ethers were carried out. The presence of third phosphino group stabilizes a transition state which enhances the rate of the reductive elimination. Triarylamines were obtained with ferrocenyl diphosphane in the presence of 2 mol% of palladium loading. Moderate to excell…

Microstructural Study of Asphalt Mixture Containing Reclaimed Material

2012

In this paper mixing of reclaimed material with virgin asphalt material has been studied non-destructively. Specimens prepared with virgin asphalt mix and with asphalt mix containing reclaimed material were scanned in X-ray Computed tomography (CT). The obtained Images were analysed for particles and pores (air voids) distribution. All the specimens were also tested in compression test and X-ray scanned while testing. It was found that distribution of reclaimed is not uniform through the samples. There is no considerable effect of increasing the mixing time on particles' distribution. Similar trend of increase in air voids (cracks) with the increase in load was found for both virgin mix and…

Evaluation of dry asphalt rubber concrete in railway sub-ballast using the four point bending test

2016

The study of bituminous mixes can be related to tyre rubber material recycling. Encouraging scrap tyre disposal and cutting down on pit employment are the environmental aims. In the field of railways, technological processes involved in the use of crumb rubber are the wet-dry processes. In the mechanical characterisation of the asphalt concrete in terms of both the fatigue resista recycled waste tires nce and the stiffness modulus it is necessary to use a design method for the sub-ballast railway material, even more so if the asphalt concrete investigated is an innovative material such as a dry asphalt rubber concrete (DARC) (i.e. a bituminous mixture with crumb rubber formed by a dry proce…

Simulation-Based Analysis of "What-If" Scenarios with Connected and Automated Vehicles Navigating Roundabouts.

2022

Despite the potential of connected and automated vehicles (CAVs), there are still many open questions on how road capacity can be influenced and what methods can be used to assess its expected benefits in the progressive transition towards fully cooperative driving. This paper contributes to a better understanding of the benefits of CAV technologies by investigating mobility-related issues of automated vehicles operating with a cooperative adaptive cruise control system on roundabout efficiency using microscopic traffic simulation. The availability of the adjustment factors for CAVs provided by the 2022 Highway Capacity Manual allowed to adjust the entry capacity equations to reflect the pr…

The azido ligand: a useful tool in designing chain compounds exhibiting alternating ferro- and antiferro-magnetic interactions

1997

A one-pot reaction of NiII 1, CoII 2, FeII 3 and MnII 4 with 2,2A-bipyridine (bipy) and azide in water leads to [M(bipy)(N3)2]n chains where the metal ion is alternatively bridged by double end-on (EO) and end-to-end (EE) azido bridges; theoretical analysis of the variable-temperature magnetic susceptibility data of 1 and 4 reveals the occurrence of intrachain alternating ferro- (through EO) and antiferro-magnetic (through EE) interactions. Julve Olcina, Miguel, Miguel.Julve@uv.es ; Lloret Pastor, Francisco, Francisco.Lloret@uv.es ; Clemente Juan, Juan Modesto, Juan.M.Clemente@uv.es

RHEOLOGY AND CURING OF TYRE RUBBER MODIFIED BITUMENS

2011

Bitumen stabilized ballast: a potential solution for railway track-bed

2016

Railway ballast degradation under dynamic loads progressively leads to loss of mechanical performance and geometry of the track, so that maintenance interventions are frequently needed. In order to system- atically avoid this issue, recently solutions have been proposed to reinforce track-bed by using polyur- ethane and/or resins as well as asphalt layers among others. Nonetheless, their main limitations are related to the high initial cost and low productivity. To cope with these limitations, in this study, bitumen stabilized ballast (BSB) is proposed as a new solu- tion for ballast stabilization. This method aims at improving durability and reducing settlement by mod- ifying both stiffnes…

A Dynamic Model of Ballasted Rail Track with Bituminous Sub-Ballast Layer

2012

AbstractThe bituminous sub-ballast layer within the ballasted rail track allows some mechanical and environmental advantages. An analytical model of a ballasted rail track with sub-ballast layer has been proposed by considering the rail as viscous-elastic continuous beam discretely supported, at four levels of elasticity.The model was used to compare the mechanical performance of both ballasted track with and without bituminous sub-ballast layer. The results confirmed that the bituminous sub-ballast layer reduces the dynamic forces on the ground and achieves the technical objectives as reduction of ground borne vibrations and increase of the design life of the rail track.

Novel performance-based technique for predicting maintenance strategy of bitumen stabilised ballast

2018

Abstract Despite being the most used worldwide, railway ballasted tracks presents high maintenance cost related to ballast settlement and particle degradation. With the aim of reducing life cycle costs, bitumen stabilised ballast (BSB) has been recently proposed as a relatively cheap alternative maintenance solution to be applied to existing tracks. This study aims at assessing the potential advantages of this technology, defining a novel maintenance strategy of traditional ballasted track-beds. A protocol for the application of the BSB technology and its associated maintenance strategy is defined. To estimate minor and major maintenance operations of BSB scenario in comparison to tradition…