Analysis of Railway Ballasted Track Stiffness and Behavior with a Hybrid Discrete-Continuum Approach

Railway ballasted track stiffness is an important indicator to identify supporting condition that ensures that the facility is well designed and functioned. Although many studies have been performed on track stiffness based on experimental tests and finite-element methods, the factors influencing the track stiffness have not been completely...

Kinetic analysis on premixed oxy-fuel combustion of coal pyrolysis gas at ultra-rich conditions: Selective combustion and super-adiabatic flame temperatures

Oxy-fuel combustion of coal pyrolysis gas has recently been proposed to serve as internal heat source of a vertical low-temperature pyrolysis furnace, in order to make the output pyrolysis gas nearly free of nitrogen and widely useful. To keep the pyrolysis temperature and the heat carrier gas volume unchanged from air combustion to oxy-fuel...

Observing the impact of urban morphology and building geometry on thermal environment by high spatial resolution thermal images

Urban surface temperature is a very important variable in the observation and understanding of energy exchange. A comprehensive understanding of the urban thermal environment is of great significance towards the adaptability of urban areas to climate hazards. The heterogeneity of urban space increases the complexity of the urban surface...

A multi-axis robot-based bioprinting system supporting natural cell function preservation and cardiac tissue fabrication

Despite the recent advances in artificial tissue and organ engineering, how to generate large size viable and functional complex organs still remains as a grand challenge for regenerative medicine. Three-dimensional bioprinting has demonstrated its advantages as one of the major methods in fabricating simple tissues, yet it still faces...

Sustained unidirectional rotation of a self-organized DNA rotor on a nanopore

Flow-driven rotary motors such as windmills and water wheels drive functional processes in human society. Although examples of such rotary motors also feature prominently in cell biology, their synthetic construction at the nanoscale has remained challenging. Here we demonstrate flow-driven rotary motion of a self-organized DNA nanostructure...

A DNA turbine powered by a transmembrane potential across a nanopore

Rotary motors play key roles in energy transduction, from macroscale windmills to nanoscale turbines such as ATP synthase in cells. Despite our abilities to construct engines at many scales, developing functional synthetic turbines at the nanoscale has remained challenging. Here, we experimentally demonstrate rationally designed nanoscale DNA...

Numerical analysis of train-track-subgrade dynamic performance with crumb rubber in ballast layer

Crumb rubber (CR) has been proposed to apply in the ballast or sub-ballast layer for ballast degradation mitigation and vibration (noise) reduction. The CR can change the ballast layer stiffness, which can affect the train-track-subgrade dynamic performance and cause travel comfort and safety issues. Towards this, this study aims at...

Coupled discrete-continuum approach for railway ballast track and subgrade macro-meso analysis

This paper presents a multi-layer railway ballast track and substructure model, where a coupled discrete and continuous method is used for macro-meso dynamic behaviour analysis under moving wheel loads. In this coupled model, the discrete element method (DEM) is utilised to build the superstructure of the ballast track (i.e. rail, fastener,...

Macro-meso dynamic analysis of railway transition zone: Hybrid DEM/FDM simulation and experimental validation

To probe into the mechanical behaviour of railway transition zone from the macro-meso aspects, a numerical model of transition zone is built that hybrids the Discrete Element Method (DEM) and Finite Difference Method (FDM). The DEM is utilised to simulate the ballast bed and sleeper, because it can consider the realistic ballast shapes and...