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,...

Calibration for discrete element modelling of railway ballast: A review

The discrete element method (DEM) has been confirmed as an effective numerical method for modelling railway ballast, and successfully used to analyse a wide range of ballast-related applications (e.g. geomaterials). However, there still exists some aspects under development. Among them, the model calibration can be the most significant one ...

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...

Improved recovery of temporal variations of the Earth’s gravity field from satellite kinematic orbits using an epoch-difference scheme

To monitor temporal variations of the Earth’s gravity field and mass transport in the Earth’s system, data from gravity recovery and climate experiment (GRACE) satellite mission and its successor GRACE Follow-On (GFO) are used. To fill in the temporal gap between these missions, other satellites’ kinematic orbits derived from GPS-based high...

Fibre-bridged fatigue delamination in multidirectional composite laminates

The influence of fibre bridging on delamination failure in multidirectional composite laminates with different thickness scales is characterized, and the dependence of fibre bridging significance on laminate thickness as well as loading regime is investigated in this paper. Both quasi-static and fatigue resistance curves (R-curve) are...

Improvements in the Monthly Gravity Field Solutions Through Modeling the Colored Noise in the GRACE Data

The Gravity Recovery And Climate Experiment (GRACE) mission has achieved a quantum leap in knowledge of the Earth's gravity field. However, current gravity field solutions still cannot reach the prelaunch baseline accuracy. One of the reasons for that is the presence of colored noise in GRACE data, which is typically ignored in the classical...

An analysis on half century morphological changes in the Changjiang Estuary: Spatial variability under natural processes and human intervention

Examination of large scale, alluvial estuarine morphology and associated time evolution is of particular importance regarding management of channel navigability, ecosystem, etc. In this work, we analyze morphological evolution and changes of the channel-shoal system in the Changjiang Estuary, a river- and tide-controlled coastal plain estuary,...

Mode I fatigue delamination growth with fibre bridging in multidirectional composite laminates

Fatigue delamination in multidirectional composite laminates was experimentally investigated in present study. Both the Paris relation and a modified Paris relation (with a new similitude parameter) were employed to interpret fatigue delamination with significant fibre bridging. The results clearly demonstrated that fatigue delamination was...

Earth’s gravity field modelling based on satellite accelerations derived from onboard GPS phase measurements

GPS data collected by satellite gravity missions can be used for extracting the long-wavelength part of the Earth’s gravity field. We propose a new data processing method which makes use of the ‘average acceleration’ approach to gravity field modelling. In this method, satellite accelerations are directly derived from GPS carrier phase...

A high resolution model of linear trend in mass variations from DMT-2: Added value of accounting for coloured noise in GRACE data

We present a high resolution model of the linear trend in the Earth’s mass variations based on DMT-2 (Delft Mass Transport model, release 2). DMT-2 was produced primarily from K-Band Ranging (KBR) data of the Gravity Recovery And Climate Experiment (GRACE). It comprises a time series of monthly solutions complete to spherical harmonic degree 120...

Visualization for the Coherent Set of 3D Property Units

There are many 3D objects with denser aggregation that they are fully/partly coherent touched with each other through shared facets, which we called coherent set of 3D objects. Visualization for 3D property unit is an effective way to understand 3D spatial occupation, location and relationship in urban space, particularly in the coherent set of...

The Applications and Practices of 3D Cadastre in Shenzhen

As the economy and urbanization develop, the expansion of the city not only develops towards the horizontal space, but also towards the vertical space. Facing the development of three-dimensional (3D) space, the traditional two-dimensional (2D) cadastral management mode cannot satisfy the need of current 3D land use and urban plan, so developing...

Updated Delft mass transport model DMT-2: Computation and validation

Validation of static gravity field models using GRACE K-band ranging and GOCE gradiometry data

The ability of satellite gravimetry data to validate global static models of the Earth’s gravity field is studied. Two types of data are considered: K-band ranging (KBR) data from the Gravity Recovery and Climate Experiment (GRACE) mission and Satellite Gravity Gradiometry (SGG) data from the GOCE (Gravity field and steady-state Ocean...

Logical Design and Implementation of the Data Model for 3D Cadastre in China

The establishment of 3D cadastre is imperative and needs support from legal, organizational and technological aspects. In Shenzhen, China, establishment of 3D cadastre has achievedgreat progress. The joint register mechanism was employedfirstly in Shenzhen, and related research is going on, including definitions, visualization and topological...

Topological Relationship Identification in 3D Cadastre

With the accelerated urbanization process, the trend of three-dimensional land use makes the traditional model of 2D cadastral management encounter challenges, because of insufficiency to express in 3D. Therefore, the 3D cadastre and related concepts have been proposed. The breadth and depth of its research are gradually broadened and refined....

3D cadastre in China: A case study in Shenzhen City

3D Cadastre in China - a Case Study in Shenzhen City

A rapid urban growth in China urges to extend land use to land space use in three dimensions due to limited land resource in cities. 3D cadastre is emerging as an effective means to support such a demands for using urban land in a way of three dimensions. Shenzhen, located in the south-eastern coastal region of China, as one of the most...