Staff publications (SAS)

Permanent URI for this collection

https://dspace.lib.cranfield.ac.uk/handle/1826/24

Browse

Now showing 1 - 20 of 902

Open Access
3D characterisation of tool wear whilst diamond turning silicon
(Elsevier Science B.V., Amsterdam., 2006-07-24T00:00:00Z) Durazo-Cardenas, Isidro; Shore, Paul; Luo, X.; Jacklin, T.; Impey, Susan A.; Cox, A.
Nanometrically smooth infrared silicon optics can be manufactured by the diamond turning process. Due to its relatively low density, silicon is an ideal optical material for weight sensitive infrared (IR) applications. However, rapid diamond tool edge degradation and the effect on the achieved surface have prevented significant exploitation. With the aim of developing a process model to optimise the diamond turning of silicon optics, a series of experimental trials were devised using two ultra-precision diamond turning machines. Single crystal silicon specimens (1 1 1) were repeatedly machined using diamond tools of the same specification until the onset of surface brittle fracture. Two cutting fluids were tested. The cutting forces were monitored and the wear morphology of the tool edge was studied by scanning electron microscopy (SEM). The most significant result showed the performance of one particular tool was consistently superior when compared with other diamond tools of the same specification. This remarkable tool performance resulted in doubling the cutting distance exhibited by the other diamond tools. Another significant result was associated with coolant type. In all cases, tool life was prolonged by as much as 300% by using a specific fluid type. Further testing led to the development of a novel method for assessing the progression of diamond tool wear. In this technique, the diamond tools gradual recession profile is measured by performing a series of plunging cuts. Tool shape changes used in conjunction with flank wear SEM measurements enable the calculation of the volumetric tool wear rate.
Open Access
Accurate measurement of the piezoelectric coefficient of thin films by eliminating the substrate bending effect using spatial scanning laser vibrometry
(Institute of Physics, 2010-06-30T00:00:00Z) Leighton, Glenn J. T.; Huang, Zhaorong
One of the major difficulties in measuring the piezoelectric coefficient d(33,f) for thin films is the elimination of the contribution from substrate bending. We show by theoretical analysis and experimental measurements that by bonding thin film piezoelectric samples to a substantial holder, the substrate bending can be minimized to a negligible level. Once the substrate bending can be effectively eliminated, single-beam laser scanning vibrometry can be used to measure the precise strain distribution of a piezoelectric thin film under converse actuation. A significant strain increase toward the inside edge of the top electrode (assuming a fully covered bottom electrode) and a corresponding strain peak in the opposite direction just outside the electrode edge were observed. These peaks were found to increase with the increasing Poisson's ratio and transverse piezoelectric coefficient of the piezoelectric thin film. This is due to the non-continuity of the electric field at the edge of the top electrode, which leads to the concentration of shear stress and electric field in the vicinity of the electrode edge. The measured d(33,f) was found to depend not only on the material properties such as the electromechanical coefficients of the piezoelectric thin films and elastic coefficients of the thin film and the substrate, but also on the geometry factors such as the thickness of the piezoelectric films, the dimensions of the electrode, and also the thickness of the substrate.
Open Access
Achieving equilibrium status and sustainable landfill - the holy grail?
(The Waste Conference Ltd, 2004-09) Hall, D. H.; Gronow, Jan R.; Smith, Richard; Blakey, N.
This paper presents the results of a research contract jointly funded by the Environment Agency and ESART examining the residues of likely post-Landfill Directive waste streams that will need to go to landfill and the time taken to achieve sufficient stabilisation such that management controls can be removed. The first part of the project has identified a number of processes that are likely to be adopted by the waste management industry in order to meet the biodegradable waste diversion targets. Both leachate quality and landfill gas generation data has been assessed for each residue stream. Forward modelling has been undertaken on these data using LandSim2.5 within GoldSim to assess the likely period of management needed in order to achieve equilibrium status.
Open Access
Acoustic monitoring of engine fuel injection based on adaptive filtering techniques
(Elsevier Science B.V., Amsterdam., 2010-12-31T00:00:00Z) Albarbar, A.; Gu, F.; Ball, A. D.; Starr, Andrew G.
Diesel engines injection process is essential for optimum operation to maintain the design power and torque requirements and to satisfy stricter emissions legislations. In general this process is highly dependent upon the injection pump and fuel injector health. However, extracting such information about the injector condition using needle movements or vibration measurements without affecting its operation is very difficult. It is also very difficult to extract such information using direct air-borne acoustic measurements.In this work adaptive filtering techniques are employed to enhance diesel fuel injector needle impact excitations contained within the air-borne acoustic signals. Those signals are remotely measured by a condenser microphone located 25cm away from the injector head, band pass filtered and processed in a personal computer using MatLab. Different injection pressures examined were 250, 240, 230, 220 and 210 bars and fuel injector needle opening and closing impacts in each case were thus revealed in the time-frequency domain using the Wigner-Ville distribution (WVD) technique. The energy of 7-15kHz frequency bands was found to vary according to the injection pressure. The developed enhancement scheme parameters are determined and its consistency in extracting and enhancing signal to noise ratio of injector signatures is examined using simulation and real measured signals; this allows much better condition monitoring information extraction.
Open Access
Adaptation to climate change: legal challenges for protected areas
(Igitur, Utrecht Publishing and Archiving Services, 2009-07-01T00:00:00Z) Cliquet, A.; Backes, C.; Harris, Jim A.; Howsam, Peter
Climate change will cause further loss of biodiversity. As negative effects are already taking place, adaptive measures are required to protect biodiversity from the effects of climate change. The EU policy on climate change and biodiversity aims at improving a coherent ecological network in order to have more resilient ecosystems and to provide for connectivity outside core areas. The existing legal framework, the Birds and Habitats Directives, can enable adaptive approaches, by establishing and managing the Natura 2000 network and providing for connectivity measures. However, policy and law so far have mainly been aimed at conserving the status quo of habitats and species within core areas. The question is whether a legal requirement to protect certain species in certain places makes sense when species and even ecosystems are migrating due to climate change. Instead, efforts must be increased to protect ecosystem functions, goods and services from the negative effects of climate change, and to facilitate the ecological restoration of new areas. Even more effort is needed for the implementation of connectivity. If existing legislation proves too weak to face these challenges, a new ‘Ecosystem Framework Directive’ might provide the necessary legal impe
Open Access
Agricultural technology and land use futures: The UK case
(Elsevier Science B.V., Amsterdam., 2009-12-31T00:00:00Z) Burgess, Paul J.; Morris, Joe
This paper explores how agricultural technology has interacted with recent land use in the UK and how it might do so in the next 50 years. From 1960 to 1985, farmers successfully used technology to increase the output of crop and animal products per unit of land and particularly of labour. This reduced the number of people employed in agriculture, and promoted larger and more specialised farm enterprises. Between 1985 and 2006, food prices were relatively low, and although labour productivity continued to increase, land productivity remained relatively static. However during this period, farmers started to address the effects of agriculture on reduced water quality and habitat loss. For established agricultural products, technological innovation tends to have an incremental effect, working through genetic improvement, the removal of abiotic and biotic stress (e.g. crop nutrition and protection, irrigation and drainage, and animal nutrition, health and housing) and the substitution of labour. Whereas the ﬁrst two processes tend to be scale-neutral, the substitution of labour is usually easiest to achieve on larger farms. Other key areas for technological innovation include addressing air, soil and water quality, biodiversity, waste reduction, and information management. Over the next 50 years, large step-changes in land use arising from agricultural technology are predicted to arise from the development of new markets for agricultural products. A strong bioenergy sector will strengthen the links between crop commodity and energy prices and will have a major effect on future land use. Climate change and the regulation of greenhouse gas emissions will alter the relative proﬁtability of crop and animal production systems. Lastly, increased public awareness of the links between food, health and the environment could substantially shift the demand for speciﬁc agricultural products. Continual improvements in agricultural technology are pivotal to providing society with the ﬂexibility to balance the challenges of improving human well-being with the management of the planet’s ecosystem. Increased technological innovation increases the probability that agricultural land can be used for other purposes, but the exact relationship is dependent on trade and environmental policies. The large external effects of agriculture mean that decisions regarding the adoption of future technologies should be taken by farmers working with other stakeholders. © 2009 Queen’s Printer and Controller of HMSO. Published by Elsevier Ltd. All rig
Open Access
Air quality and worker health effects in materials recovery facilities (MRFs) in England and Wales.
(Eurowaste, 2003-10) Gladding, T.; Thorn, Jörgen; Smith, Richard
There are varying types of Materials Recycling Facilities (MRFs, also known as Materials Recovery Facilities, or Materials Recycling Factories) in operation in the UK and throughout Europe. A full outline of the various types of MRF operations is given by the Institute of Wastes Management (IWM 2000). This review concentrates on MRFs used to sort and process sourcesegregated household and commercial waste, the most common type. A MRF that deals with household and commercial waste is defined as a central operation where source-segregated, dry, recyclable materials are sorted, mechanically or manually, to market specifications for processing into secondary materials.
Open Access
Alley coppice-a new system with ancient roots
(EDP Sciences, 2014-07-01T00:00:00Z) Morhart, Christopher D.; Douglas, Gerry C.; Dupraz, Christian; Graves, Anil R.; Nahm, Michael; Paris, Pierluigi; Sauter, Udo H.; Sheppard, Jonathan; Spiecker, Heinrich
Context: Current production from natural forests will not satisfy future world demand for timber and fuel wood, and new land management options are required. Aims: We explore an innovative production system that combines the production of short rotation coppice in wide alleys with the production of high-value trees on narrow strips of land; it is an alternative form of alley cropping which we propose to call 'alley coppice'. The aim is to describe this alley coppice system and to illustrate its potential for producing two diverse products, namely high-value timber and energy wood on the same land unit. Methods: Based on a comprehensive literature review, we compare the advantages and disadvantages of the alley coppice system and contrast the features with well-known existing or past systems of biomass and wood production. Results: We describe and discuss the basic aspects of alley coppice, its design and dynamics, the processes of competition and facilitation, issues of ecology, and areas that are open for future research. Conclusion: Based on existing knowledge, a solid foundation for the implementation of alley coppice on suitable land is presented, and the high potential of this system could be shown.
Open Access
Amplitude of probability density function (APDF) of vibration response as a robust tool for gearbox diagnosis
(Blackwell Publishing Ltd, 2012-12-31T00:00:00Z) Rzeszucinski, P. J.; Sinha, J. K.; Edwards, Rodger; Starr, Andrew G.; Allen, B.
A ‘Go' or ‘No Go' assessment is a safety requirement for quick and robust estimation of the condition of gearboxes used in helicopters and other critical machines. A range of vibration-based condition indicators (CIs) has been developed to meet this requirement. CIs are compared automatically with pre-set threshold values representing a healthy system, so that the health of the gearbox can be assessed and diagnosis made where necessary. The use of kurtosis of the residual signal of the measured vibration data, computed as part of the ‘FM4' method, is widespread, because it is accepted as a good and reliable indicator. However, it has been observed in some cases that FM4 may not show a continually increasing trend with the propagation of a fault. This behaviour may lead to improper assessment of the severity of the fault. Hence, a new CI, based on the deviation in the normal probability density function (PDF) of the measured vibration data, is suggested which demonstrates an increasing trend that is more robustly and monotonically correlated with the fault propagation.
Open Access
Anaerobic digestion foaming causes – A review
(Elsevier, 2009-12) Ganidi, Nafsika; Tyrrel, Sean F.; Cartmell, Elise
Anaerobic digestion foaming has been encountered in several sewage treatment plants in the UK. Foaming has raised major concerns for the water companies due to significant impacts on process efficiency and operational costs. Several foaming causes have been identified over the past few years by researchers. However, the supporting experimental information is limited and in some cases absent. The present report aims to provide a detailed review of the current anaerobic digestion foaming problem and to identify gaps in knowledge regarding the theory of foam formation in anaerobic digesters.
Open Access
Anaerobic workout
(Institution of Chemical Engineers, 2010-11-30T00:00:00Z) McAdam, Ewan J.
Anaerobic technology cannot directly replace current wastewater treatment processes exclusively. The UASB reactor configuration removes slightly less organic carbon by comparison as the process relies on lamella separation for passive clarification rather than using fine pores like anMBR. By contrast, whilst anMBR can operate as a single unit process for organic carbon removal, the membrane surface has to be cleaned using gas sparging to limit surface deposition, which requires extra energy. One can demonstrate the significance of nitrogen removal on total energy demand using the UASB-ASP flowsheet as an example. Lower temperatures increase the solubility of dissolved gases, in accordance with Henry's law. Novel secondary technologies increase both the environmental and economic horizon by realizing energy positive wastewater treatment and the potential to generate new product streams.
Open Access
Analyses of Power Output of Piezoelectric Energy-Harvesting Devices Directly Connected to a Load Resistor Using a Coupled Piezoelectric-Circuit Finite Element Method
(IEEE Institute of Electrical and Electronics, 2009-07-31T00:00:00Z) Zhu, Meiling; Worthington, Emma; Njuguna, James A. K.
A coupled piezoelectric-circuit finite element model (CPC-FEM) is proposed for the first time to study the power output of a vibration-based piezoelectric vibration-based piezoelectric energy harvesting devices (EHDs) that is directly connected to a resistive load. Special focus is given to the effect of the resistive load value on the vibrational amplitude of the piezoelectric EHDs, and thus on the current, voltage, and power generated by the EHDs. In the literature, these outputs are widely assumed to be independent of the resistive load value for the reduction in complexity of modelling and simulation. The presented CPC-FEM uses a cantilever with sandwich structure and a seismic mass attached to the tip to study the following load characteristics of the EHD as a result of changing the resistive load value: (1) the electric outputs of the EHD: current through and voltage across the resistive load, (2) the power dissipated by the resistive load, (3) the vibration amplitude of tip displacement of the cantilever, and (4) the shift in resonant frequency of the cantilever. Investigation results shows significant dependences of the vibration characteristics of the piezoelectric EHDs on the externally connected resistive load are found, rather than independence as previously assumed in most literature. The CPC-FEM is capable of predicting the generated power output of the EHDs with different resistive load value while simultaneously calculating the effect of the resistive load value on the vibration amplitude. The CPC-FEM is invaluable for validating the performance of designed EHDs before fabrication and testing, thereby reducing the recurring costs associated with repeat fabrication and trials. In addition, the proposed CPC-FEM is potentially useful in device designs optimisations for maximal power generation.
Open Access
Analysing oily wastes in soils
(Institution of Chemical Engineers, 2009-12-31T00:00:00Z) Coulon, Frederic
Many hydrocarbon contaminated sites posing potential risks to human health harbour weathered, ‘mid-distillate' or heavy oils. Now, a bioremediation consortium (PROMISE), led by Cranfield University, has developed a novel and robust analytical procedure for weathered hydrocarbon contaminated soils within a UK risk-based framewo
Open Access
Analysis of cold weather patterns over the period 1991-2012
(2013-01-22T00:00:00Z) Farewell, Timothy S.; Hallett, Stephen H.; Truckell, Ian G.
Within the context of an observed increase in the numbers of burst pipes associated with colder winters in the Anglian water region, we have analysed temperature data for England and Wales from the period 1991-2012 to identify cold winter periods. To do so, we have calculated the annual accumulated temperature below 1 °C for each MORECS square over the winter period. The resulting data has been mapped for both the whole of England and Wales as well as just for the Anglian Water region. The data shows that the four winters between 2008-2012 were considerably colder than the preceding eleven winters. Additionally, for the winter of 2011-2012, the average temperature for all England of Wales was warmer than the 1991-2011 period average. However locally, in the Anglian Water region, the average temperatures were colder than the 1991-2011 average. The available MORECS data shows that while there are some periods of time with warmer winters (e.g. 1997-2008) and periods with colder winters (1990-1994, 1995-1997 and 2008- 2012), the lengths of these periods are considerably variable. From the MORECS data for the period 1991-2012, there does not appear to be a cyclical or predictable pattern in determining the harshness of the winter period.
Open Access
Analysis of petroleum-contaminated soils by diffuse reflectance spectroscopy and sequential ultrasonic solvent extraction-gas chromatography
(Elsevier Science B.V., Amsterdam., 2014-01-31T00:00:00Z) Okparanma, R. N.; Coulon, Frederic; Mouazen, Abdul Mounem
In this study, we demonstrate that partial least-squares regression analysis with full cross-validation of spectral reflectance data estimates the amount of polycyclic aromatic hydrocarbons in petroleumcontaminated tropical rainforest soils. We applied the approach to 137 field-moist intact soil samples collected from three oil spill sites in Ogoniland in the Niger Delta province (5.317N, 6.467E), Nigeria. We used sequential ultrasonic solvent extractionegas chromatography as the reference chemical method. We took soil diffuse reflectance spectra with a mobile fibre-optic visible and near-infrared spectrophotometer (350e2500 nm). Independent validation of combined data from studied sites showed reasonable prediction precision (root-mean-square error of prediction ¼ 1.16e1.95 mg kg1, ratio of prediction deviation ¼ 1.86e3.12, and validation r2 ¼ 0.77e0.89). This suggests that the methodology may be useful for rapid assessment of the spatial variability of polycyclic aromatic hydrocarbons in petroleum-contaminated soils in the Niger Delta to inform risk assessment and remediation.
Open Access
Analysis of surface roughness in relation to soil loss and runoff at high rainfall intensities.
(John Wiley & Sons, Ltd, 2002-08-30T00:00:00Z) Idowu, O. J.; Rickson, R. Jane; Godwin, R. J.
The decay of roughness is an important factor governing surface processes such as infiltration and soil erosion. Thus the decay of surface roughness under different surface conditions was investigated and related to quantitative amounts of soil loss, runoff and sediment concentration in a laboratory experiment. Rainfall with an intensity of 128 mm/h was applied to a bare or mulched surfaces of a sandy loam soil with known surface roughness at specified time intervals. The decay of roughness as expressed by roughness ratio, in this experiment, was better predicted when related to an exponential function of the square root of cumulative kinetic energy of rainfall rather than with the cumulative rainfall. The roughness decay equations in literature did not predict breakdown under mulched surfaces accurately. Thus the exponent parameters of the roughness decay equations were adjusted to reflect the reduced decay occurring under mulched surfaces. In a bare soil, regression equations expressing the dependent variables as a function of initial roughness index were significant, but with low coefficients of determination, being 0.39 for soil loss, 0.12 for runoff and 0.36 for sediment concentration. In addition to initial roughness index, cumulative kinetic energy of rainfall was further included in the regressions. This led to an increase in coefficients of determination, which was 0.81 for soil loss, 0.74 for runoff and 0.49 for sediment concentration. The coefficients of determination (0.87 for soil loss, 0.85 for runoff and 0.51 for sediment concentration) were further increased when the final roughness index was included in addition to initial roughness index and cumulative kinetic energy in the regressions. This work shows that soil loss and runoff could be predicted from bare soil surface provided the initial roughness and the energy of rainfall is known. However, field verifications of these relationships are needed under different tillage tools and under natural rainfall. Copyright (C) 2002 John Wiley Sons, Ltd.
Open Access
Analysis of the 2007/8 Defra Farm Business Survey Energy Module
(2010-11-30T00:00:00Z) Williams, Adrian G.; Pearn, Kerry R.; Sandars, Daniel L.; Audsley, Eric; Parsons, David J.; Chatterton, Julia C.
Key points This study has delivered an invaluable baseline estimate of energy use and greenhouse gas (GHG) emissions on commercial farms in England. Energy use and GHG emissions associated with particular commodities were quantified and results broadly agreed with those derived by Life Cycle Assessment, but with much scatter in the environmental performance of farms.Direct energy use on farms was generally less that indirect (embedded) energy use, except for horticulture, which is dominated by heating fuel use. In contrast, most GHG emissions are incurred on farms, rather than as embedded emissions.Scatter in both environmental and economic performance underlies the somewhat disappointing finding of no clear positive link between farm financial performance and energy use or GHG emissions. However, the mere existence of these ranges shows that there is scope for improvement in both financial and environmental performance and that there is no apparent barrier for both to be achievable in harmony. The recording of such farm-level energy data is essential for the future, as it should enable improvements to be made in efficiency of energy use. The improved UK agricultural GHG inventory will depend on high quality energy data on agricultural activities. This study will be invaluable in identifying the level of detail needed. Future data requirements include: contractor work rates and fuel use per unit area and per unit time, fertiliser and pesticide use by brand name, enhanced output data, especially animal live weights, and horticultural produce recorded by weight rather than by value.
Open Access
Apparent Reduction in the Value of the d 33 Piezoelectric Coefficient in PZT Thick Films.
(Taylor & Francis, 2002-01-01T00:00:00Z) Dorey, Robert A.; Whatmore, Roger W.
Thick PZT films (1 - 20 m) have been prepared using a composite sol gel technique whereby PZT powder and a PZT producing sol are formed into a slurry and spin coated onto silicon wafers. The maximum relative permittivity obtained was approximately 80% of that exhibited by bulk PZT of comparable composition. However, the d 33, f and e 31, f [1] piezoelectric coefficients were shown to be significantly lower than that of bulk PZT. It has been proposed that the measured value of d 33, f is affected appreciably by particle-particle rotation and substrate clamping leading to reduced poling efficiency which may also greatly reduce the value of e 31, f observed. Samples with high levels of porosity have been shown to exhibit a reduced value of d 33 . This was attributed to 31 and 51 mode piezoelectrically generated charges caused by the bending and shearing of particle-particle bridges. The effect of substrate clamping, on d 33, f and poling, has been studied by monitoring the changes in position and intensity of the (200)/(002) X-ray diffraction (XRD) peaks of composite films. The presence of the substrate was found to introduce tensile stresses parallel to the film plane which distorted the unit cell. Subsequent permanent polarisation following poling was found to be reduced due to the presence of these stresses. The discrepancies between the values of d 33 measured on thick films and bulk ceramics were highlighted as being of particular importance if thick film materials are to be modelled for device applications. Thick film piezoelectric coefficients (i.e. those of the combined film-substrate structure) should not be used in place of material piezoelectric coefficients when attempting to model the behaviour of devices. Such actions would inevitably lead to erroneous results.
Open Access
The application of a new research and development project selection model in SMEs.
(Elsevier Science B.V., Amsterdam., 2006-02-01T00:00:00Z) Lawson, Craig P.; Longhurst, Philip J.; Ivey, Paul C.
The work reported in this paper investigates Research and Development (R&D) project selection models, focusing on the application of a new hybrid project selection model in a UK based engineering Small to Medium-sized Enterprise (SME). Work is done to enable the new project selection model to be applied in an SME and the model is then field tested. Field test results provide insight into the barriers to the adoption of such a model in an SME, either as a decision support tool or as a knowledge acquisition and learning tool. Insights are gained into the suitability and limits that exist within SMEs for the use of such decision support models. As an outcome of the field test results a simple R&D project portfolio cash-flow tracking method is proposed.
Open Access
Application of an ecosystem function framework to perceptions of community woodlands
(Elsevier Science B.V., Amsterdam., 2009-07-01T00:00:00Z) Agbenyega, Olivia; Burgess, Paul J.; Cook, Matthew; Morris, Joe
Owners, local residents, government, and conservation organisations can express divergent preferences in the development and management of local woodlands. The perceptions of these four groups were examined, in the context of three community woodlands in Eastern England, using an ecosystem function framework. In a pilot study, residents were able to allocate a relative importance to woodland ecosystem services which were then related to “regulation”, “habitat”, and “production” or “information” functions. However residents also placed importance on negative services or “dis-services” associated with the woodland ecosystem. Therefore a fifth category of “dis-services” was included in the main survey which included 84 local residents, three woodland owners, three government institutions, and six representatives from conservation groups. Each of the four groups placed greatest importance on services associated with habitat (16–39% of the total importance) and information (30–50%) functions suggesting, in this example, mutual interest in the use of woodlands as a habitat or recreational resource. By contrast a potential area of difference was the particularly high importance placed by one owner on dis-services such as fly tipping. In addition the woodland owners placed higher importance (10–20%), than local residents and conservation groups (7–9%), on the productive services of the wood. This suggests a need for communication when production-related operations affect recreation. The ecosystem function framework appears to be a useful approach for highlighting potential tensions and areas of mutual interest in the manage