Evaluation of a risk assessment system for heritage railway earthworks

There are currently over 100 heritage railways in the UK carrying 6.8 million passengers on 15 million passenger journeys and contributing an estimated £579 million to the UK economy. Many of these lines include significant earthworks, which present a considerable risk to their safe operation. In the last decade there have been major slips at several heritage railways causing major disruption to operations and a serious threat to business continuity. This research describes the application of a risk assessment system based on that used by Network Rail but specifically adapted for heritage railway conditions. Adaptations include significant alterations to the consequence categories used in prioritization of earthwork issues and a simple low-cost method of implementation based on paper forms and Excel spreadsheets. Use of the system on two heritage railways, the Bo’ness and Kinneil Railway and the Strathspey Railway is evaluated by means of discussion with railway engineering staff and civil engineering volunteers. It is concluded that whilst the system represents a realistic and useful approach to management of earthwork assets, the system could not be used by heritage railway volunteer staff without targeted training. Such training, however, would be straightforward to provide, perhaps under the auspices of the Heritage Railway Association

Breakage functions of particles of four different materials subjected to uniaxial compression

Particle breakage is a common problem in the conveying and handling of particulate solids. The phenomenon of particle breakage has been studied by experiments by a number of researchers in order to describe the process of breakage by mathematical functions. The development of comminution functions that can suitably describe the breakage behavior of granular materials can lead to a significant improvement in the design and efficiency of particulate solids handling equipment. The present study focuses on developing the strength distribution and the breakage functions of particles of four different materials subjected to uniaxial compressive loading. Single particles were compressed until fracture in order to determine their strength distribution and the fragments were investigated to determine their size distribution. The parameters of logistic function and breakage function were obtained by curve-fitting of the functions to the strength distribution and size distribution of the fragments respectively. These functions were then implemented in the BGU-DEM code which was used to carry out Discrete Element Method (DEM) simulations on single particle breakage by compression. The simulations produced a similar mass distribution of fragments to the breakage function obtained from the experimental data

Exotic structures on magnetic multilayers

To characterize the possible magnetic structures created on magnetic multilayers a model has been formulated and studied. The interlayer inhomogeneous structures found indicate either (i) a regular periodic, (ii) a quasiperiodic change in the magnetization or (iii) spatially chaotic glass states. The magnetic structures created depend mainly on the ratio of the magnetic anisotropy constant to the exchange constant. With the increase of this ratio the periodic structures first transform into the quasiperiodic and then into the chaotic glass states. The same tendency arises with the depolarization of the magnetic moments of the first layer deposited on the substrate.Comment: 4 pages, 1 figur

U02581 Group Design Potable Water Supply - Project Brief 2007-2009

This group design project for MEng students in the School of Engineering and Electronics is intended to introduce students to multidisciplinary planning and design. The project should develop creative thinking, team skills, and an improved understanding of other disciplines

X-ray absorption fine structure of adsorbates on metal surfaces

The structural techniques of SEXAFS. NEXAFS and photoelectron diffraction have been applied to several adsorption systems. In combination they have allowed detailed surface structural studies to be achieved and the usefulness of these complementary techniques (which employ the same experimental geometry) has been demonstrated. SEXAFS studies have been carried out for atomic and molecular adsorption systems. It has been found that for several systems the (usual) Fourier filtering analysis method is not applicable due to the superposition of EXAFS from different shells. Some systems have been successfully analysed by the Fourier method, however. In particular, EXAFS from the Cu(111) [ √3x√3] R30°-Cl adsorption system yield the same result when analysed by both the Fourier filtering method and a multiple shell simulation routine. Adsorption occurs in the three-fold hollow with a Cl-Cu bond length of 2.39±0.02Ǻ. This is in contrast with earlier analysis of I chemisorbed on Ni(100) where it was found that only the multi-shell method was applicable. Photoelectron diffraction measurements for both normal and off-normal geometries confirmed the site found by SEXAFS and further revealed that adsorption was in the fcc-like three-fold hollow (as opposed to the hcp-like one). A study of the formate intermediate on Cu(110) using NEXAFS revealed that the molecule is adsorbed with it’s plane parallel to the [1ī0] azimuth. Single shell SEXAFS analysis determined the adsorption site to be atop a Cu atom on the 'ridges' with the 0 atoms in the pseudo bridge sites. The average O-Cu distance being l.98±0.O7Ǻ. Reanalysis of the SEXAFS data of formate adsorbed on Cu(110) and Cu(100) using the multi-shell method revealed that the 'anomalous chemisorption bond' proposed for the latter was erroneous. A misleading result had been obtained with the Fourier filtering method because of the superposition of EXAFS from two similar bond lengths. NEXAF studies of the reaction of ethanol and oxygen on Cu(110) revealed that ethanol and an ethoxy intermediate were coadsorbed with the 0-C bond effectively parallel to the surface in the ethanol and perpendicular in the ethoxy

Simulating the Hydrodynamics of Self-Propelled Colloidal Clusters using Stokesian Dynamics

Self-propelled clusters are involved in many technological applications such as in material science and biotechnology, and understanding their interaction with the fluid that surrounds them is of a great importance. We present results of swimming velocity and energy dissipation obtained through Stokesian dynamics simulations of self-propelled clusters. The clusters are of diffusion limited aggregates (DLA), consisting of force- and torque-free spherical particles. The number of particles per cluster ranges from 100 to 400, and with two fractal dimensions of 2.1 and 2.4. The clusters are self-propelled by imposing an explicit gait velocity applied in the x, y and z directions. It is found that the swimming velocity of the cluster and the energy dissipation are strongly dependent on the number of particles in the cluster and its fractal dimension, and on the orientation of the imposed explicit gait velocity. It was found that the rotational velocity of the self-propelled clusters decreases as the number of particles within the cluster is increased, n line with experimental observations reported recently in the literature

Self – Propelled Nanofluids a Path to a highly Effective Coolant

We propose a new self-propelled nanofluid having advantageous thermal and rheological properties at the same time. The nanofluid consists of a low volume fraction of self-propelled particles known as Artificial Bacterial Flagella (ABF), which will swim as pushers in a manner similar to the swimming of E-coil microorganisms with flagella. A theoretical model is introduced, describing the mechanisms responsible for the reduction of viscosity. The model shows that the swimming velocity of the particle and its geometry play an essential role in the reduction of the suspension viscosity. The results obtained from the theoretical model compare qualitatively with experiments in the literature. The model shows a significant decrease in viscosity at very low volume fractions, and that the viscosity of the suspension is reduced as the volume fraction of the particles increases. Using an in-house finite volume code, we numerically simulate natural convection effects in our ABF self-propelled nanofuid inside a square cavity heated from its vertical sides. Simulations are conducted at volume fractions of 0.7%, 0.8% and 0.83%, comparing the performance of a self-propelled nanofluid with conventional non-active nanofluids (i.e. carbon nanotubes in water). The results show that the heat transfer rate measured by the Nusselt number is three times higher than for the case of classical nanofluids and pure water at the same operating conditions and 0.83% volume fraction of particles. Also, due to the very dilute volume fractions of particles in the proposed nanofluid, their stability can endure for long operating times. There is also a significant decrease in the viscosity (around 25 times lower than water) which will result in a significant reduction in the pumping power

Simulating Geobag Revement Failure Processes

An experimental and numerical study has been carried out to help develop design guidelines for the construction of low-cost river bank protection using geobags. Building upon previous work, a 1:10 scale model was tested in a laboratory flume, comparing two different construction methods (running bond and stack bond), subjected to three different water depths. It was found that whilst the failure pattern was highly dependent on water depth, the construction method had no noticeable impact, and it was concluded that the dominating factor is the friction between individual geobags, which itself is dependent on bag overlap rather than specific construction method. A simple Discrete Element Method (DEM) model was constructed using the LIGGGHTS open source software with drag and lift models applied to a multi sphere simulation of the laboratory model geobags. It was found that despite its simplicity this DEM model could reproduce the failure pattern of revetments very well, and thus has potential for future use in developing design guidelines aimed at the developing world

Calibration of a Hydraulic Model for Seasonal Flooding in a Lowland River with Natural Diversions and Bathymetric Uncertainty, for Dam Downstream Impact Assessment

A method is developed to generate bank-full river main channel geometry, to complement an open-source Digital Elevation Model (DEM) and produce a calibrated hydraulic model reproducing the extent of historically observed overbank flooding. This approach relies on limited surveyed cross section and flow rate information and is potentially suitable for projects in developing countries where the availability of measured data is limited. The method presented is applied to the case of the seasonal flooding of the Baro River in the Gambela floodplain in Ethiopia, modelled with a two-dimensional hydraulic model. The simulated flooding extent for the 1990 wet season is compared with the observed flooding from 1990 satellite imagery and the expected flow interaction patterns with the near Alwero River, showing good agreement. The calibrated model is also used to show the impact of the planned TAMS hydropower dam on the Baro River flooding

The health and safety implications of socio-cultural context for community construction projects in developing countries

Community participation in construction during rural infrastructure projects in developing countries is encouraged by many non-governmental organizations. The health and safety aspects of this type of development model have not previously been adequately researched, however. The aim is to identify the socio-cultural factors that motivate community members to participate in construction activities which they perceive as hazardous during a case study of a water and sanitation project in rural Ghana. This is a step towards understanding how health and safety can be more effectively managed during community development projects. A qualitative approach has been taken, using interview, observation and reflection. It was found that the communal culture of the local context resulted in community members feeling pressurized to participate in hazardous construction activities. Local customary laws further compelled individuals as they were concerned they could be fined or arrested should they not fulfil their communal obligations. Further work is required to determine the boundaries within which findings apply but it is likely that there are implications for others managing community construction projects both in Ghana and further afield