Viscoelastic stress modeling in cementitious materials using constant viscoelastic hydration modulus

Viscoelastic stress modeling in ageing cementitious materials is of major importance in high performance concrete of low water cement ratio (e.g. w/c ~0.35) where crack resistance due to deformation restraint needs to be determined. Total stress analysis is complicated by the occurrence of internal stresses due to shrinkage, which requires...

Performance analysis of railway infrastructure and operations

Research on performance assessment of railway networks and companies has been stimulated by the European policy of deregulation of transport markets, the opening of national railway networks and markets to new entrants and separation of infrastructure and train operation. Recent international benchmarking studies of railways based on statistical...

An Optimization Model for Simultaneous Periodic Timetable Generation and Stability Analysis

We present an optimization model which is able to generate feasible periodic timetables for networks given the line structure and the requested line frequencies, taking into account infrastructure constraints and train overtake locations. As the model uses the minimum cycle time as the objective function, the stability of the timetable is also...

Benchmark analysis of railway networks and undertakings

Benchmark analysis of railway networks and companies has been stimulated by the European policy of deregulation of transport markets, the opening of national railway networks and markets to new entrants and separation of infrastructure and train operation. Recent international railway benchmarking studies which are mostly based on statistical...

Micro-hydration, pore connectivity and durability of cementitious materials

Latest developments in Hymostruc enable the possibility to evaluate the pore connectivity of an evolving microstructure while also considering the contribution of the ITZ and air voids and to examine the influence on frost durability. The numerical model is used to visualize this phenomenon and to show the contribution of both the pores and the...

Cryogenic suction pump mechanism for combined salt-and frost exposure

Freezing of water can be explained by the thermodynamic properties of the water due to the influence of temperature, pressure and special effects such as surface tension and salt solution. Gibbs free energy curves for ice and pore liquid containing different concentrations of NaCl (0-6%) are presented. These curves explain the onset of freezing...

Development of tidal watersheds in the Wadden Sea

The Wadden Sea consists of a series of tidal lagoons which are connected to the North Sea by tidal inlets. Boundaries to each lagoon are the mainland coast, the barrier islands on both sides of the tidal inlet, and the tidal watersheds behind the two barrier islands. Behind each Wadden Island there is a tidal watershed separating two adjacent...

Effectiveness of dynamic reordering and rerouting of trains in a complicated and densely occupied station area

Railway traffic experiences disturbances during operations while dispatchers need actions to restore feasibility and limit spreading of delays through the network. To help the dispatcher in such task, the dispatching support tool ROMA (Railway traffic Optimization by Means of Alternative graphs) has been designed and implemented. We report on...

Railway Network Timetabling and Dynamic Traffic Management

The paper discusses the current state of research concerning railway network timetabling and traffic management. Timetable effectiveness is governed by frequency, regularity, accurate running, recovery and layover times, as well as minimal headway, buffer times and waiting times. Analytic (queuing) models and stochastic micro-simulation are...

Delay propagation and process management at railway stations

Process operators at large railway stations have the difficult task to secure a fluent train traffic flow while minimizing deviations from established timetables. Variation in actual train departure times is inevitable due to many circumstances such as arrival delays and fluctuations in alighting and boarding time, even if some buffer time is...

Delay distributions in railway stations

The estimation of the precise arrival and departure times of trains at stations is done by means of a software tool that extracts the occupation and clearance times of each train per track section of the Dutch Railways‘ network. The software tool was applied to the whole automatically collected set of signal data of the area of Eindhoven during...

Improving railway punctuality by automatic piloting