PhD, EngD, MPhil and MSc by research theses (SAS)

Permanent URI for this collection

https://dspace.lib.cranfield.ac.uk/handle/1826/23

Browse

Now showing 1 - 20 of 618

Open Access
A methodology for cost and risk reduction in purchasing and supply management.
(Cranfield University, 2010-09) Younis, Kieron; Tiwari, Ashutosh
Automotive manufacturers in the UK and other industrialised nations face competitive pressures from rivals with lower underlying cost bases. Reducing costs and risks is of increasing importance, and purchasing and supply management can make a substantial contribution to this. This work delivers a validated methodology for meeting the challenges that purchasers are most often facing in automotive manufacturing facilities operating in industrialised markets. The aim of this research is to develop a novel methodology for identifying and implementing cost reduction activities for the purchasing function of automotive companies. Specifically the methodology presented here defines activities which implement continuous improvement in the purchasing process including; costing, sourcing, stocking, and social responsibility assessment. A literature review and interviews with practitioners in industry were used to explore how strategic purchasing is implemented in the field and identify the key issues facing practitioners. Using these findings, a skeleton methodology for strategic purchasing and supply management was developed. This skeleton methodology brought together; (i) the capturing of social responsibility competency in the supply base and a formal means of measuring and reporting supplier compliance, (ii) techniques for the identification of price reduction candidates and the comparison of dissimilar supplier bids, and (iii) techniques for the identification of stock reduction candidates and the use of supplier knowledge in stock reduction. A study was conducted to address each of these areas individually the results of which were validated through real-world findings from the purchasing environment of the industrial collaborator. The skeleton methodology was validated using a series of questionnaires with experts from industry and academia. The corporate social responsibility component of the methodology identified suppliers which posed a potential resourcing risk to the industrial collaborator, the acquisition cost reduction component found 8% of cost savings, and the inventory holding reduction component found 7% savings. The methodology has been shown to provide an operational link between a manufacturer’s strategic need to reduce costs and risks and the capabilities of purchasing functions and professionals. The implications of this work are that purchasing can now be used as a means to achieve a competitive advantage.
Open Access
Conductivity grading in epoxy graphene oxide composites using thermal reduction.
(Cranfield University, 2014-02) Chatzi, Panagiota; Skordos, Alexandros A.
The aim of this project is the development of a method for the production of conductivity graded polymeric materials through the in-situ reduction of Graphene Oxide (GO). These types of composites can be used for the reduction of electrical field concentrations observed in several applications, such as cables, cable joints, microelectronic components and bushings. The evolution of electrical conductivity of GO was monitored during thermal reduction under isothermal and dynamic heating thermal conditions and compared with the kinetics of the reduction reaction as observed using calorimetry. These results were replicated in epoxy/GO composite to prove the feasibility of in-situ reduction and capabilities for controlling this process. In addition, reduction was achieved in epoxy/GO composites using infrared continuous and pulsed laser. It was shown that thermal reduction is possible in the cured epoxy composite at relatively low temperatures up to 26ᴼC. The kinetics of reduction follows a double mechanism which can be represented using a double n-th order process. Electrical measurements showed that conductivity increased significantly up to 0.12 S/m for dry particles and 0.09 S/m for the composite. Heat transfer by conduction and irradiation on specific areas resulted in selective reduction, and a conductive graded material.
Open Access
Design analysis and fabrication of a mobile energy harvesting device to scavenge bio-kinetic energy.
(Cranfield University, 2014-05) Daniels, Alice Charlotte Hilda; Zhu, Meiling; Tiwari, Ashutosh
The increasing prevalence of low power consumption electronics brings greater potential to mobile energy harvesting devices as a possible power source. The main contribution of this thesis is the study of a new piezoelectric energy harvesting device, called the piezoelectric flex transducer (PFT), which is capable of working at non- resonant and low frequencies to harvest bio-kinetic energy of a human walking. The PFT consists of a piezoelectric element sandwiched between substrate layers and metal endcaps, the endcaps are specifically designed to amplify the axial force load on the piezoelectric element, instead of conventional designs of piezoelectric energy harvesters that focus on utilising resonant frequency in order to increase power harvested. This thesis presents the analyses, design, prototyping and characterisation of the PFT using a coupled piezoelectric-circuit finite element model (CPC-FEM) to show the energy harvesting capability of the proposed and developed novel device to harvest bio-kinetic energy. Prior to the study of the new PFT, an initial focus was given to a traditional Cymbal device to investigate its potential as a bio-kinetic energy harvesting device. To gain an understanding, effects of geometrical parameters and material properties of the device on its energy harvesting capability were studied and in doing so issues and problems were identified with the traditional Cymbal device for use as a bio-kinetic energy harvesting device. Its structural materials were not able to withstand higher than a 50N applied load and it was proposed that a small adhesion area connection in a fundamental part of the structure may have been at high risk of delamination. In order to study these, the CPC-FEM model was developed using the commercial software of ANSYS and validated by experimental methods. Later, based on a modelling and experimental study, a novel PFT was proposed and implemented to overcome the issues and problems of the traditional Cymbal device. For this initial study, the Cymbal was analysed by studying how key dimensional parameters affect the energy harvesting performance of the Cymbal. In addition to this, how piezoelectric material properties affect the energy harvesting performance were studied using the developed CPC-FEM model through comparisons of different piezoelectric materials and their electrical performances to aid with selecting high power producing materials for the final PFT design. It was found that (1) d₃₁ is a more dominant material property over other material properties for higher power output, (2) Figure of Merit (FOM) was more linear related to the power output than either the k₃₁ or the d₃₁, and (3) εᵀ r₃₃ had some role when the materials have an identical d₃₁; a lower ε ᵀ₃₃ was preferred. A combined FOM with d₃₁ parameters is recommended for selection of piezoelectric material for a higher power outputs. The design of the new PFT is partly based on the traditional Cymbal however, the new PFT has more potential for withstanding higher forces due to an addition of substrate layers that reduced delamination risks. Using a similar approach to designing the traditional Cymbal, the new PFT was designed and tested with force frequencies of less than 5Hz and forces of up to 1kN. In the design process, the validated CPC-FEM was used 1) to analyse then utilise correlations between geometric parameters and power outputs, and 2) to ensure structural integrity by monitoring mechanical stress in the PFT. The PFT was retrofitted into a shoe and the harvested power was used to power an in-house developed wireless sensor module whilst the subject with a body weight of 760N was wearing the shoe and ran at 3.1mph (equivalent to 1.4Hz on the shoe), the PFT produced an average maximum power of 2.5mW over 2MΩ load and the power produced is able to power the wireless module approximately every 10 seconds.
Open Access
The application of electrolytic in-process dressing to precision grinding processes
(2007-06) Zervos, Charilaos; Stephenson, David J.; Robinson, M. J.
Electrolytic In-Process Dressing (ELID) has attracted a lot of attention in recent years as it is a promising method of grinding a wide range of materials, including ones that are difficult to machine, to high quality finishes. The EC funded project Nanogrind undertook the construction of a high precision grinding machine which will incorporate an ELID system, applying the technique on a spherical wheel for the production of components with intricate geometries (e.g. freeforms, aspherics). In this project, the main objective was to understand the basic features of ELID, such as the electrochemical properties of the oxide layer and its effect on the final finish of the produced components (glass, a hard and brittle material was the main focus). Acoustic emission studies, a promising in-process monitoring tool, verified the effectiveness of ELID grinding when the contact area between the wheel and workpiece is increased. Compared to conventional resin bond wheel grinding, ELID ground components were of higher quality with less damage introduced in them. ELID current monitoring also gave excellent results when it was correlated to surface finish achieved across the surface of the testpieces ground. Electrochemical Impedance Spectroscopy was an innovative technique that was applied in order to acquire basic information about the metal bond wheel, such as the charge transfer resistance. Its correlation to the oxide layer thickness gave an indication of the way corrosion rates change with the presence or not of an oxide film on the wheel surface. Finally, sub-surface damage introduced into glass components was evaluated and was compared to the depths of damage predicted by theoretical models, giving further insight into the way the overall processing time of a component should be optimised in order to acquire high quality, damage-free finished components in a time efficient, cost effective way.
Open Access
Maximising struvite recovery from real wastewater sources
(2007-04) Thomas, David J. L.; Parsons, Simon
Formation of struvite (MgNFLjPCU.ôFfeO) in reactors is proposed to limit struvite problems in sewage treatment works (STW) and offer a method of phosphorus recovery and recycling. Four sites of interest were identified by Severn Trent Water Ltd: Derby, Wanlip, Stoke Bardolph STW and Coleshill sludge destruction plant for their potential to produce struvite. Initial tests on sludge liquors collected from the four sites showed that >80% of initial orthophosphate could be removed when the Mg:PC>4 ratios was adjusted to >2:1 for Wanlip, Stoke Bardolph STW and Coleshill at pH 9. Two reactor types, a fluidised bed reactor (FBR) and a stirred tank reactor, were trialled in Phase 1 testing with Wanlip STW liquors. The FBR was able to achieve a >90% orthophosphate removal with Mg additions of 3.5 to 5 mmol but produced a suspended solid content of -300 mg L"1. To overcome the problem of ‘fines’ a metallic mesh accumulation device was fitted to the reactor. The mesh system was able to reduce the suspended solids within the liquors <50mg L' 1 when the reaction time was increased from two to three hours. The stirred tank reactor was able to remove on average 55% of the phosphate content of the liquors with a magnesium addition of 5mmol. In Phase 2 testing both types of reactor were run side-by-side in a continuous operation. In the three experiments carried out the initial orthophosphate concentration was adjusted to 95 mg L' 1 (Immol). The stirred tank reactor was able to consistently remove -65% of the influent orthophosphate concentration in the 3 experiments at a Mg:P0 4 ratio of 3.5:1. The FBR removal steadily improved from 25% to 65% over the 3 experiments. The metallic mesh system was further trialled here and successfully captured 4.1 g of struvite. A cationic polymer, polyDADMAC, was also tested for the capture of fines with less success than in previous reports. The precipitate from each reactor was analysed with SEM-EDS and XRD. The FBR produced relatively pure struvite and stirred tank a struvite and amorphous material mixture.
Open Access
Towards sustainable landfill management
(2006-11) Smith, Richard; Pollard, Simon
The UK is reliant on landfill as a waste management option with some 72% w/w of municipal waste landfilled in 2003/04. This thesis advances an argument that landfill, as practised historically and currently, is unsustainable. This thesis demonstrates, specifically, that current legislative aftercare provisions of 30-60 years are inadequate with reference to modelled landfill completion times (the achievement of equilibrium status) of up to 2,000 years. Uniquely, the research quantifies the scale and significance of methane emissions during the early stages (up to 28 months waste age) of landfill operations at 21 UK landfills using a modified flux box. The onset of methanogenesis is quantified for the first time, using a series of in situ monitoring probes installed at one UK landfill site. A significant and novel finding is that the advective flow of landfill gas is preferentially dominated by lateral movement, evidenced here by examination of a predominantly municipal solid waste (MSW) landfill site in Southern England. The direct implications of this finding for the design of landfill gas management systems are discussed. For future landfills, this research has examined a number of UK scenarios in which the gas and leachate characteristics from waste residues going to landfill are modelled to the point of completion or achievement of equilibrium status. This analysis now allows for a comparative assessment of the future performance of landfills. Under these scenarios, completion times can be reduced in some instances {e.g. landfilling of compost and mechanical biological treatment residues) and extended in others (incinerator bottom ash). Problematic contaminants remain; notably arsenic, chromium and lead. Using the research herein, the work describes the application of a landfill gas management hierarchy. In part response to the requirements of the EU Landfill Directive, this provides a science-based framework for operators to maximise protection of the environment and human health from gaseous emissions. The research provides evidence that can be used by landfill managers seeking to maximise landfill collection efficiency. This contributes to regulators managing public and environmental health and is increasingly significant for climate change.
Open Access
Process parameter sensing for remote hyperbaric welding
(2009-08) Papadopoulos, Konstantinos; Yapp, D.
Pipeline ovality and equipment set-up variations pose a challenge for offshore remote hyperbaric welding operations using a fillet welded sleeve for pipeline repair. The distance from the torch to the pipe should be kept as constant as possible to maintain optimum welding process stability. The work of this research project was focused on using through-the-wire sensing and the establishment of the feasibility of Dip Resistance measurement as a suitable method for real time contact tip to work-piece distance estimation and control under Hyperbaric Welding conditions. Analysis of cases of Dip Resistance application in 1 Atm and factors of influence has been performed and their relevance and importance for the RPRS program is examined. Suitability of the Dip Resistance is concluded and verification of this under hyperbaric conditions is tested. For this purpose, a data acquisition hardware system was built and software was written using Lab VIEW 7.1 in order to acquire and analyse the welding signals in real-time and store the signals for later analysis. A second program focused on the analysis of the Dip Resistance information was written using Lab VIEW 7.1 in order to analyse the experimental data off-line and to evaluate the results in more detail. Experiments were made using various welding patterns so as to determine the feasibility of the method of the use of Dip Resistance information as a method for real-time estimation and control of the weld process. Based on these results, three detection algorithms were evaluated and the most suitable one was selected for further investigation. Initial investigation on other factors of influence like the length of the welding current’s path and resistance variation with temperature is examined. The results from the experiments and their off-line analysis are presented and a discussion of the results is presented. It is concluded that real-time control of the contact tip to work-piece distance torch may be achieved in real-time using dip resistance monitoring if it used in conjunction with the welding current and welding voltage signals allows achievement of robust control. Suggestions for further study and achievement of a complete solution are presented.
Open Access
A system development methodology for embedded applications
(2009-07) Goh, Kiah Mok; Tjahjono, Benny; Baines, Tim
In recent years, Singapore’s manufacturing sector has contributed more than a quarter of the total Gross Domestic Product (GDP) and has established global leadership positions in several manufacturing areas such as electronics, Information Technology (IT) and industrial automation. The Singapore Economic Review Committee (ERC) recommendation states that “software and embedded systems that drive products are one of the most important technologies for the manufacturing sector. “ With the increasing adoption of automated and intelligent products, embedded systems have emerged as a crucial technology for Singapore. However, the development of embedded applications is not a trivial undertaking as it can usually involve multi-discipline parties and different application platforms. Most embedded application developments use either vendor specific or desktop based methodologies. Vendor specific methodologies constrain the company to rely on the specific vendor's solutions, whereas desktop-based methodologies are not well suited to embedded application development. Therefore, this research aims to develop a standard-based system development methodology for embedded applications. The research programme comprises 5 stages. The first stage reviews the existing system development methodologies for embedded applications. The next stage formulates the proposed conceptual methodology followed by the development of the proof-of-concept tool to demonstrate the merits of the proposed approach. The methodology is then tested and evaluated respectively by using industrial experiments and feedback from a workshop. The final stage refines the methodology based on the feedback and presents the final system development methodology. The research has provided a sound foundation which future research in methodology for embedded applications to develop further.
Unknown
The influences of post-preparative treatments on luminescence from CdTe nanoparticles
(2008) Gardner, Hannah Catherine; Dunn, S. C.
Nanotechnology has seen an explosion of research interest in recent years. Nanoparticles are finding applications in an ever growing list of applications. To further develop these applications an understanding of the properties of a nanoparticle is needed. This thesis prevents an investigation of the photoluminescent properties of CdTe nanoparticles as a function of various post-preparative treatments. Changing the inter-particle distance is found to cause photoluminescence wavelength shifts. These shifts are determined by the amount of energy transferred between nanoparticles. The effects of interparticle distance are seen when a suspension is diluted, re-concentrated or deposited as a thin film. In a thin film format similar effects are seen if the number of layers in a thin film is increased. Changing the temperature of either a thin film or suspension of nanoparticles produces both reversible and irreversible photoluminescence wavelength shifts. The reversible changes are mainly found to be due to the presence of thermally activated trap states within the nanoparticles. Finally, formation of a thin film via the layer-by-layer deposition method is studied. A real time in-situ analysis technique is used to monitor the whole deposition process. The deposition is found to take place in a series of stages with nanoparticles becoming either strongly or loosely bound to the surface. Optical waveguide lightmode spectroscopy is found to be an extremely useful technique for monitoring this thin film deposition as it allows researchers the opportunity to quickly and easily characterize individual experimental setups.
Open Access
Cost of a package plant membrane bioreactor
(2007-05) Fletcher, Harriet Kate; Judd, Simon J.
The capital and operating costs associated with a small package plant MBR for smallscale domestic duty has been appraised based on a medium-strength municipal wastewater. The three main membrane configurations were considered, these being multi-tube, hollow fibre and flat sheet, with the most appropriate plant design chosen for each configuration. The analysis proceeded via a consideration of the estimated amortised capital costs of the plant individual components and their installation, coupled with operating costs based largely on energy demand and residuals management. Energy demand was calculated from aeration and pumping costs, with aeration based on a combination of empirical relationships for membrane aeration and mass balance, and the modified Activated Sludge Model version 2 used for estimating tank size and sludge generation. Results indicate that it is possible to produce a single household MBR at a capital cost similar to the current market cost for package treatment plants. Desludging and maintenance of these plants is similar but power requirements for an MBR are around 4 times that associated with more conventional package plants. Economies of scale exist from 6-20 p.e. plants but above 20 p.e. there is little cost difference per head, due to the design assumptions made. CAPEX and OPEX are to some extent interchangeable; reductions in CAPEX are associated with an increase in OPEX and vice versa. Whilst costs are high, the market for package MBRs is significantly influenced by the recycling potential of the effluent produced. A cursory comparison has also been made with conventional package plant treatment processes.
Open Access
The damaging effect of surface-traffic-generated soil pressures on buried archaeological artefacts
(2010-04-12) Dain-Owens, Anne Peregrine; Kibblewhite, Mark G.; Godwin, R. J.; Hann, M. J.
The aim of this work was to investigate the influence of surface loading from conventional field operations on the damage to buried artefacts, both pots and bones. The objectives of this research were a) to investigate the influence of surface loading and resulting breakage relating to the material strengths of buried objects - ceramic (unglazed), and aged bone; b) to assess the magnitudes of peak subsurface pressures transferred through soil under the dynamic surface loading from tyres and other field operations; c) to develop and test an empirical model for predicting the effects of subsurface pressure application on buried objects from surface loads; and d) to explore ways of identifying the potential for damage to buried artefacts under agricultural and other field operations. Experimental investigations were performed in both the laboratory and field. The laboratory work was undertaken to determine the magnitude of subsurface pressure at which buried objects were damaged. Conducted in a sandy-loam-filled soil bin, instrumented ceramic and bone artefacts were buried alongside pressure sensors and subjected to loading by a single smooth tyre appropriately loaded and inflated for subsurface pressure generation. The breakage of the buried objects and the pressures under the moving tyre were recorded in order to allow correlation of the subsurface pressures to buried artefact breakage. The fieldwork was done to determine the magnitudes of subsurface pressure generated by individual field operations whilst travelling in a similar sandy loam field soil. Four plots were established, with each assigned a particular cultivation regime. An accelerated timeframe was utilized so that a years’ series of field operations could be driven over pressure sensors buried in the soil. The peak pressures from each field operation within each plot were recorded and summarized, and the data was analysed relative to field operation type and cultivation regime type. Multiple statistical analyses were performed, as the laboratory data and field data were independently evaluated before being correlated together. An empirical relationship between buried object damage and subsurface pressure magnitude was developed. The different pot types and bone orientations broke at different subsurface pressures. The four pot types listed in ascending order of strength to resist damage (with breakage pressure threshold value) are: shell tempered (1.3 bar), grog tempered (1.6 bar), flint tempered (3.1 bar), and sand tempered (3.6 bar). Aged human radius bones were tested, and the parallel bone orientation proved stronger than the perpendicular orientation, where 2.8 bar was the lowest subsurface pressure found to cause damage. The primary field operations, presented in ascending order relative to peak magnitude of subsurface pressure per specific operation, are: roll (0.68 bar), drill (1.03 bar), heavy duty cultivator (1.21 bar), spray 1 (1.27 bar), harvester (1.30 bar), spray 2 (1.31 bar), tractor / trailer (1.46 bar), shallow mouldboard plough (1.61 bar), deep mouldboard plough (2.04 bar). The relationships between vehicle specification and subsurface pressure generation potential were described, relating to the vehicle mass, tyre/track physical properties, and tyre inflation pressure. The effect of cultivation method on overall magnitude of subsurface pressure was defined, with lowest pressure generation within a zero-till cultivation regime (1.08 bar), higher in a non-inversion cultivation regime (1.13 bar), followed by the shallow inversion regime (1.22 bar), and highest within a conventional inversion scheme (1.30 bar). The laboratory and field results were correlated by a statistical analysis comparing breakage point to peak subsurface pressure. The shell tempered pot was found to be most susceptible to damage. The grog tempered pot was less vulnerable to damage, followed by the flint tempered pot. The quartz tempered pot was predicted to survive intact under all field operations within this research. In conclusion, this research has developed a functional and predictive empirical relationship between damage to pot and aged bone artefacts from subsurface soil pressures generated by surface traffic. It has been found that different types of buried pot and bone artefacts break at different subsurface pressures. In addition, a complete dataset consisting of peak subsurface pressures recorded under a year’s range of field operations within a sandy loam soil at field-working moisture content has been compiled. The effect of different cultivation methods on the generation of subsurface pressures was also evaluated. The breakage thresholds specific to each artefact type have been related to the in-field subsurface soil pressures. A correlation of breakage to the subsurface pressures under each operation yields a prediction of percentage of artefact-type breakage. From this correlation, relationships are observed between vehicle specification, subsurface pressure generation, and consequential artefact breakage. The achievements provide knowledge about how field operations affect specific types of buried archaeology, providing a valuable asset to farmers, land managers, and regulatory bodies. It is evident that agricultural practices, choice of track or tyre type, and inflation pressures must be carefully managed if the intention is to protect or mitigate damage to buried archaeological artefacts. Thus, a contribution has been made to the development of ‘best management practices’ and to the specification and use of field operations relative to intended mitigation of buried artefact damage.
Open Access
Investigating the relationship between shear and floe fate using CFD
(2006-11) Bridgeman, Jonathan Matthew; Parsons, Simon; Jefferson, Bruce
The size, density and strength of floes play a major role in the removal of contaminants from water in physico-chemical treatment processes. The efficiency of the main removal processes is a function of floe size, strength and density. Changes in these parameters affect floe removal and hence the removal of adsorbed organic matter. Coagulation and flocculation efficiency and floe strength are often assessed using ajar tester. Here, computational fluid dynamics (CFD) was used to model the flow field within standard jar test apparatus and, using a Lagrangian particle trajectory model, to study the effects of turbulence on individual floes. The hydrodynamic environments were also investigated experimentally using laser Doppler anemometry (LDA) and particle image velocimetry (PIV) measurement techniques. Combining numerical and experimental data, velocity gradient values at which floe breakage occurs were postulated for three different floe suspensions. Although the threshold values are determined using jar test and CFD data in combination, they are based on the floes’ resistance to induced velocity gradients. This is a significant result, as previous breakage thresholds have been expressed only in terms of mixing speed and cannot be applied at full scale. With this in mind, work was subsequently undertaken to use CFD to model numerically the hydrodynamic conditions within two full scale flocculation vessels; one mechanically mixed, the other hydraulically mixed. This section of work had two principal aims; firstly, to investigate the perceived benefits of using CFD to model the hydraulic performance of the flocculation process at two large surface water treatment works, and secondly, to investigate the practicality and effectiveness of using CFD and jar test results in combination to consider floe fate in the flocculation vessels (in terms of growth, breakage and residence time). This work drew upon the results and conclusions of the previous laboratory scale work and facilitated a greater insight into flocculation processes. Improved understanding of flocculator hydrodynamics can only serve to improve design procedures and standards for future installations.
Open Access
A process-based approach to engineering design knowledge reuse
(2007-06) Baxter, David; Gao, James X.
Manufacturing enterprises are under increasing pressure to produce products of higher quality at lower cost in shorter time frames if they are to remain competitive. Engineering design support methods can help companies to achieve these goals. One such approach is ,,design knowledge reuse. Industrial requirements have been identified as (i) the ability to rapidly create product variants; (ii) the ability to capture and re-use design knowledge, and; (iii) the capability to support the design effort across a distributed enterprise. The research aim is developed to assist the manufacturing enterprise in meeting the industrial requirements in the following way: a design solution to a new product requirement can be supported using an application package that is developed for a specific product domain. The application package consists of knowledge about previous products and projects, and procedures for using the knowledge to achieve a new solution. An initial investigation showed that design reuse in practice is lacking in specific areas: access to relevant and contextualised captured design knowledge; the relationship between design reuse and the product development process; integrated engineering and business objectives. Literature gaps were also identified. They include: (i) knowledge reuse for the whole product life cycle (particularly early design); (ii) integrated product and design process models; (iii) a 'how-to' element of the product design process. The aim of this research is to provide a method for reusing engineering design knowledge. The research method is 'interview case study', which supports a flexible approach and enables the research to develop according to the findings. The research was carried out with four companies, one of which took part in a detailed case study, providing case data to develop, populate and validate the proposed system. The outcome of the research is a proposal for a process based engineering design reuse method. The method consists, of a combination of product, process and task knowledge to support the design process. Product knowledge is represented using a product ontology. Process knowledge is represented using the Design Roadmap method. Task knowledge is represented using a template developed to record the critical aspects of the task, including 'how-to' knowledge. Case studies are used to validate the proposed framework and the developed prototype system. The proposed design knowledge reuse framework is applicable to a range of industries in which mature, complex products are developed.
Open Access
Modelling the drivers of soil moisture in the landscape in order to apply the STAMINA model at a regional level
(2007-01) Baggaley, Nicola J.; Mayr, T.
The STAMINA (Stability And MItigatioN of Arable systems in hilly landscapes) model is a new crop yield model than takes into account the impact of terrain on crop growth. The ability to model yield variations as a function of terrain can help policy makers plan for potential changes in climate. In its original form the STAMINA model is too complex to be run at a regional extent. The literature pointed to the key drivers of crop growth being linked to water availability in the Iandscape. The research was therefore split into two sections. The first section outlines the investigation of soil moisture in the landscape. Two field experiments were undertaken. The first measured surface soil moisture at over 100 locations, using a Delta-T ThetaProbe on eight occasions in three different fields. The results from regression models showed that up to 80% of the variation in surface soil moisture can be explained using 1:10,000 taxonomic soil units. Radiation and wetness indices combined explained a maximum of 41% of the variation. These variables also explained significant additional variation when combined with 1:25,000 soil units. The second experiment measured soil moisture at six depths from 100 mm to 1 m at 38 locations in two fields using a Delta-T profile probe. Regression models showed that 1:10,000 taxonomic soil units combined with depth explain up to 67% of the variance in soil moisture. These results highlight the importance of the drainage characteristics of the soil profile in determining soil moisture content. The second section focuses on the development of an index approach to apply the STAMINA model at a regional extent. This method and STAMINA version 1.8 were tested on three representative catchments in a 10 km2 area of Bedfordshire. They succeeded in highlighting similar areas of the landscape that are at risk from low yields. Grid size analysis suggested that a grid size of 100 m was sufficient for running the index based version of the STAMINA model. This still maintained an accurate representation ❑f the topographic features that control the modelled yield variability. Further investigation into the soil hydrology module in STAMINA version 1.8 suggested that predicted yield was very sensitive to a change in the way soil water drainage was modelled, in particular the potential for a soil to recharge over the winter months.
Open Access
A methodology for the distributed and collaborative management of engineering knowledge
(2007-09) Aziz, Hayder; Gao, J
The problems of collaborative engineering design and management at the conceptual stage in a large network of dissimilar enterprises was investigated. This issue in engineering design is a result of the supply chain and virtual enterprise (VE) oriented industry that demands faster time to market and accurate cost/manufacturing analysis from conception. Current tools and techniques do not completely fulfil this requirement due to a lack of coherent inter-enterprise collaboration and a dearth of manufacturing knowledge available at the concept stage. Client-server and peer to peer systems were tested for communication, as well as various techniques for knowledge management and propagation including Product Lifecycle Management (PLM) and expert systems. As a result of system testing, and extensive literature review, several novel techniques were proposed and tested to improve the coherent management of knowledge and enable inter-enterprise collaboration. The techniques were trialled on two engineering project examples. An automotive Tier-1 supplier which designs products whose components are subcontracted to a large supply chain and assembled for an Original Equipment Manufacturer (OEM) was used as a test scenario. The utility of the systems for integrating large VEs into a coherent project with unified specifications were demonstrated in a simple example, and problems associated with engineering document management overcome via re-usable, configurable, object oriented ontologies propagated throughout the VE imposing a coherent nomenclature and engineering product definition. All knowledge within the system maintains links from specification - concept - design - testing through to manufacturing stages, aiding the participating enterprises in maintaining their knowledge and experience for future projects. This potentially speeds the process of innovation by enabling companies to concentrate on value-added aspects of designs whilst ‘bread-and-butter’ expertise is reused. The second example, a manufacturer of rapid-construction steel bridges, demonstrated the manufacturing dimension of the methodology, where the early stage of design, and the generation of new concepts by reusing existing manufacturing knowledge bases was demonstrated. The solution consisted of a de-centralised super-peer net architecture to establish and maintain communications between enterprises in a VE. The enterprises are able to share knowledge in a common format and nomenclature via the building-block shareable super-ontology that can be tailored on a project by project basis, whilst maintaining the common nomenclature of the ‘super-ontology’ eliminating knowledge interpretation issues. The two-tier architecture developed as part of the solution glues together the peer-peer and super-ontologies to form a coherent system for internal knowledge management and product development as well as external virtual enterprise product development and knowledge management. In conclusion, the methodology developed for collaboration and knowledge management was shown to be more appropriate for use by smaller enterprises collaborating in a large Virtual Enterprise than PLM technology in terms of: usability, configurability, cost of system and individual control over intellectual property rights.
Open Access
Information and communication technology (ICT) in the early years of education
(2008) Abdalla, Eman Shafik Hassan; Lemon, Mark
Information and communication technology (ICT) has become an important factor in the education field, especially for pupils with special educational needs. The aim of this research is to understand how ICT is perceived to affect the learning capability of primary age pupils, including those with special educational needs. The specific objectives are to: (i) Investigate the literature about the relationship between information and communication technology (ICT) and pupils with special educational needs; (ii) Identify some of the factors that affect the use of information and communication technology (ICT) for assisting pupils’ learning (reading and writing) ability in three case studies school; (iii) Investigate the current use of ICT resources in three schools and the roles played by teachers and parents in these schools to help pupils learn in both classroom and home environments; (iv) Assess the perceived impact of ICT on pupils’ learning through observation and interviews in the case study schools; (v) Communicate examples of best practice, for both teachers and parents, on more effective way of using ICT to improve pupils’ learning. The research has been carried out in three schools one of which is a special school for pupils with special educational needs. Data have been collected in three ways. Firstly, direct observation has been carried out in the classroom; secondly, interviews have been carried out with teachers; and finally a survey of 175 parents was carried out by questionnaire. The key finding drawn from this research indicate that ICT is perceived to have a positive impact on pupils’ learning regardless of their educational needs. The study also identified that ICT is perceived to improve the quality of teaching and ICT use by primary age children. A second issue raised the shortage of teacher training for ICT, especially staff development, and finally, teachers and parents needed time to become skilled with the new technologies before attempting to teach with them. The study presents examples of best practice to distinguish between how teachers and parents might improve their support for pupils using ICT. These include the need for teachers to match learning needs, style and curricula and for parents to understand how their pupils learn and the nature of any learning problem.
Open Access
Manufacture of novel intermetallic bond coats from the electroplating of ionic liquids
(2010) Craig, Mark; Nicholls, J. R.; Robinson, M. J.
Gas turbine engines for both aerospace and power generation are constantly being revised to improve running efficiency and performance. Gas turbine engines essentially consist of three distinct regions: compressor, combustion and turbine sections with the combustor and turbine sections required to experience higher and higher temperatures in pursuit of efficiency gains. Stage 1 high pressure turbine blades (buckets) are located closest to the combustion zone and experience extremely high temperatures. Further, turbine blades experience high centrifugal force whilst in operation and therefore engine designers must take into consideration both the mechanical effects o f operation and the high temperatures associated with engine use. Environmental resistant coating systems are therefore employed to allow the design of the base material (nickel-based superalloys) to be biased towards mechanical properties (high creep resistance). Nickel-platinum-aluminide coatings are the diffusion coating of choice for both aero-and industrial turbines with the platinum being typically deposited by electroplating on the nickel alloys, followed by heat treating to form a platinised enriched area which is then aluminised by insertion into a chemical vapour deposition (CVD) retort and reacting with an aluminium halide at elevated temperature. The CVD process is utilised as it is relatively easy to form desirable intermetallics though this route. The electrodeposition of aluminium from aqueous media is not possible as water undergoes hydrolysis before the reduction potential of aluminium is reached. Ionic liquids are an alternative method o f depositing aluminium via electroplating without the need o f water as the electrolyte. Ionic liquids have numerous benefits including a wide electrochemical window and have low toxicity. In comparison to the CVD process, they are multiuse and can be easily recycled/reused as the ionic liquid itself is not consumed within the plating process. Electroplating aluminium from ionic liquids to form a dense coating onto nickelbased superalloys is therefore proposed within this thesis as an alternative novel approach to achieving desirable nickel aluminide intermetallic coatings after post processing heat treatment. Furthermore, the post heat treatment may be done within either a traditional CVD-type regime or with a new and novel low temperature heat treatment regime developed as part of this thesis - ICON. Both heat treatments form β-NiAl. The heat treatment using CVD-type parameters forms coatings akin to those produced using a CVD route, whereas the ICON coating shows improved chemical homogeneity and a smaller interdiffusion zone - both o f which are shown to offer superior coating oxidation performance. Aluminium electrodeposited on CMSX4 heat treated with CVD-type parameters shows excellent cyclic oxidation data which is at least equal to, if not greater than those produced using traditional methods.
Open Access
Developing a current capability design for a manufacture framework in the aerospace industry
(Cranfield University, 2008-09) Whiteside, A.; Shehab, Essam
During progressive product design and development in the aerospace industry, a lack of effective communication between the sequential functions of design, manufacturing and assembly causes delays and setbacks whereby production capabilities are unable to realise design intent in high-complexity product models. There is a need to formalise the progressive design and release of an engineering model to production functions during New Product Introduction (NPI) via defining key stages of definition maturity and information requirements through a structured process. This research develops a framework to facilitate optimal Design for Manufacture and Assembly (DfMA) based on current manufacturing capabilities within the aerospace industry, promoting effective knowledge management at all stages of design definition. The framework was developed through the accomplishment of a series of objectives: (1) Investigate optimal DfMA principles and process capability analysis through a comprehensive literature review, (2) capture the current practice of progressive drawing release in the aerospace and automotive sectors, (3) create a route map of the release process built around the optimal critical path, (4) define roles and procedures to follow at each stage and (5) validate the proposed process framework through expert opinion. These objectives were achieved through the adoption of a four-stage qualitative methodology. The framework promotes the understanding and identification of the major stages, activities, responsibilities and information requirements throughout a structured design release process where quantified manufacturing capability data is incorporated within early design definition activities. Adherence to the process route-map ensures that no engineering model is released that cannot be realised by manufacturing and assembly functions. This facilitates the efficient organisation of information on an optimal concurrent engineering platform, leading to a reduction in product development leadtimes and re-work through informed design.
Open Access
ISO roadmap for software products
(Cranfield University, 2010-09) Ihrig, Aboud; Mehnen, Jorn
The complex nature of ISO 9001 standards has been an obvious limitation for implementation. ISO 9001 accreditation provides external and internal advantages. The external benefits include increased market access and customer confidence. The internal advantages include quality improvements in both the product and process. However, this research demonstrates that the current ISO guideline for software products has not completely fulfilled the expectations in its implementation within the software organisation. Numerous companies are experiencing difficulties with ISO implementation and maintenance. Based on the analysis provided by this research, poor communication and an unsystematic approach were identified as the main current problems associated with ISO implementation. In addition, it also shows that the organisations often underestimate internal organisation factors, such as resistance to change. The existing difficulties in maintaining applied quality systems have resulted in a lack of control and monitoring. This thesis introduces an ISO Roadmap and corresponding Checklist for software products. The main goal of this ISO Roadmap is to provide enhanced transparency and assistance in the application of ISO 90003:2004 in order to make ISO implementation more manageable, visible and understandable for all people involved within the organisation. The result of this research provides the software industry with an initial step towards better systematisation and control for ISO implementations. This should help the software industry to better navigate through the ‘ISO jungle’ and facilitate an improved approach for implementation and maintenance activities. This research relied heavily on the development of the literature review, ISO 90003 standards, and knowledge from interviewees ... [cont.].
Open Access
Computer aided design of involute gear shaper cutters
(Cranfield University, 2007-10) Butans, Jevgenijs; Tiwari, Ashutosh
The global market competition has put a pressure on the industry to reduce lead time and increase quality of parts. In particular, the area of gear cutting tool design requires capability to rapidly produce tool designs with increased tool geometry precision. The aim of this research is to explore the field of gear shaper cutter design and produce a model and software that would enable creation of more precise cutter designs, faster. A literature survey of involute cylindrical gearing geometry highlights deficiencies in addressing industry requirements of tool manufacturing, as most of the research in the area is focused on problems of gear design, but not tool design. This research, therefore, focuses on the process of gear manufacturing using the gear shaper cutters. It attempts to develop an analytical model and a set of tools that are able to aid the design process of gear shaper cutter. With cylindrical gear being essentially " at" and therefore easier to express an- alytically, the focus of recent papers has shifted to non-cylindrical and non-involute gear trains. Yet the geometry of the tools used to produce cylindrical gears remains largely untapped area, in particular the geometry of gear shaper cutters. The knowl- edge about the profile of the cutter teeth and the profile cut by the cutter in the gear blank are essential for high precision gear manufacturing. The gear shaper cutter is a metal cutting tool and therefore should be re-sharpened on a regular basis. These re-sharpening operations change the profile of the tool and, consequently, the profile of the gear it cuts. The changes in the cutter and gear geometry are analysed in this thesis and a way to calculate the life span of the tool is suggested. Gear shaper cutter profiles usually have one or more modifications to the theoret- ical ideal involute profile applied. Some of these modifications are used to produce a better cutter profile, while other should in turn produce modifications to the gear profile, and, finally, some are used to overcome generated gear profile constraints. Computer-Aided Design (CAD) software for gear shaper cutter design should be able to show the profile of the cutter and the profile cut by the cutter with arbitrary modifications applied. The analysis and visualisation of gear shaper cutters profiles cut by these cutters is impossible without a clear understanding of the principles of operation of gear generation hardware, generating motion and different machine geometry, all being covered in this thesis. In order to verify the analytical model and the CAD software case studies of the real-life gear shaper cutter designs were performed.