Recent Submissions

  • ResearchGate: Disseminating, communicating, and measuring Scholarship?

    Thelwall, Mike; Kousha, Kayvan; Statistical Cybermetrics Research Group; School of Mathematics and Computer Science; University of Wolverhampton; Wulfruna Street Wolverhampton WV1 1LY UK; Statistical Cybermetrics Research Group; School of Mathematics and Computer Science; University of Wolverhampton; Wulfruna Street Wolverhampton WV1 1LY UK (2015-05)
  • Combination of finite element method and Drucker-Prager Cap material model for simulation of pharmaceutical tableting process

    Baroutaji, A.; Lenihan, S.; Bryan, K.; School of Mechanical, Electrical and Process Engineering, Cork Institute of Technology, T12 P928; BISHOPSTOWN, CORK IRELAND; School of Mechanical, Electrical and Process Engineering, Cork Institute of Technology, T12 P928; BISHOPSTOWN, CORK IRELAND; School of Mechanical, Electrical and Process Engineering, Cork Institute of Technology, T12 P928; BISHOPSTOWN, CORK IRELAND (Wiley, 2017-11)
    Density-dependent Drucker-Prager Cap (DPC) model is widely used for assessing the compaction behaviour of powders due to its capability of capturing the various phenomena associated with the powder compaction process such as work hardening, nonlinear densification, and frictional and compressible behaviour of the powder. This paper presents a full description of the Drucker-Prager Cap model for the compaction behaviour of microcrystalline cellulose (MCC) Avicel PH101 pharmaceutical powder. The experimental calibration process of Drucker-Prager Cap is detailed and all model parameters are calculated as a function of powder relative density. Also, the calibrated parameters are implemented in finite element code to perform a numerical simulation of a typical pharmaceutical tablet. The results showed that the finite element model (FEM) was able to accurately predict the compaction behaviour of the microcrystalline cellulose powder. Furthermore, the finite element predictions of stress and density distributions of the powders during the compaction were used to analyse the failure mechanisms associated with tableting.
  • The development of an implementation model for ICT in education: an example of the interaction of affordances and multimodality

    Hadfield, Mark; Jopling, Michael (2014-06-18)
    This paper discusses the development of a model targeted at non-specialist practitioners implementing innovations that involve information and communication technology (ICT) in education. It is based on data from a national evaluation of ICT-based projects in initial teacher education (ITE), which included a large-scale questionnaire survey and six in-depth case studies. It draws on affordance and multimodality theory to address, and move beyond, considerations of the role played by the usability and utility of technology in any implementation. It argues that the perceived ‘status’ of technologies is a key factor in the success of an innovation.
  • Implementing The Last PlannerTM System in a Road Construction Project in Nigeria

    Ahiakwo, Ograbe; Oloke, David; Suresh, Subashini; Khatib, Jamal. (2015)
    This paper describes a research investigation into the implementation of the Last Planner System (LPS) in a road construction project. LPS is known to be the most developed practical use of Lean Construction. It focuses on minimising the negative impacts of variability, uncertainties, buffers, making projects more predictable, creating reliable work plans and convalescing collaborative planning. LPS is unpopular in highway and road construction projects, as a lot of case studies have been recorded of its application on infrastructure and building projects as against highway and road projects. However in the road project. In order to achieve this aim, an Action Research strategy is adopted using different data collection methods such as interviews, observation and survey questionnaire. The initial state of production plan reliability within this case project was observed to be highly unreliable with a high degree of variability. However as the implementation commenced, production plans were stabilized with an improved reliability in the schedules. The results from this study demonstrate that although a road construction process is a linear process, a number of benefits were still recorded in terms of improving construction planning and control processes, during the implementation.
  • Development of a 3D finite element acoustic model to predict the sound reduction index of stud based double-leaf walls

    Arjunan, A.; Wang, C.J.; Yahiaoui, K.; Mynors, D.J.; Morgan, T.; Nguyen, V.B.; English, M. (Elsevier, 2014-11)
    Building standards incorporating quantitative acoustical criteria to ensure adequate sound insulation are now being implemented. Engineers are making great efforts to design acoustically efficient double-wall structures. Accordingly, efficient simulation models to predict the acoustic insulation of double-leaf wall structures are needed. This paper presents the development of a numerical tool that can predict the frequency dependent sound reduction index R of stud based double-leaf walls at one-third-octave band frequency range. A fully vibro-acoustic 3D model consisting of two rooms partitioned using a double-leaf wall, considering the structure and acoustic fluid coupling incorporating the existing fluid and structural solvers are presented. The validity of the finite element (FE) model is assessed by comparison with experimental test results carried out in a certified laboratory. Accurate representation of the structural damping matrix to effectively predict the R values are studied. The possibilities of minimising the simulation time using a frequency dependent mesh model was also investigated. The FEA model presented in this work is capable of predicting the weighted sound reduction index Rw along with A-weighted pink noise C and A-weighted urban noise Ctr within an error of 1 dB. The model developed can also be used to analyse the acoustically induced frequency dependent geometrical behaviour of the double-leaf wall components to optimise them for best acoustic performance. The FE modelling procedure reported in this paper can be extended to other building components undergoing fluid–structure interaction (FSI) to evaluate their acoustic insulation.
  • Reference Module in Materials Science and Materials Engineering

    Baroutaji, A.; Carton, J.G.; Sajjia, M.; Olabi, A.G. (Elsevier, 2015-12)
  • Methodology for Project Risk Assessment of Building Construction Projects Using Bayesian Belief Networks

    Odimabo, Onengiyeofori O; Oduoza, Chike; Suresh, Subashini (Scientific & Academic Publishing, 2017-11)
    The study aims to establish a risk assessment methodology to improve the performance of building construction projects especially in developing countries. A survey of randomly selected samples to evaluate risk factors experienced by construction practitioners was conducted based on the likelihood of occurrence and impacts on projects. A response rate of 53% comprising 305 contractors and subcontractors and 38 clients was received. Risk Acceptability Matrix (RAM) was used to rank/prioritise risk factors in order to determine critical risks that could affect building construction projects especially in developing countries. Bayesian Belief Network was then constructed by structural learning and used to appreciate the relationship amongst the risk factors. Results showed that critical risks affecting building construction projects were mainly improper construction methods, poor communication between involved parties, supplies of defective materials, delayed payment in contracts, fluctuation of materials prizes and unsuitable leadership style.
  • A Computationally-Efficient Numerical Model to Characterize the Noise Behavior of Metal-Framed Walls

    Arjunan, Arun; Wang, Chang; English, Martin; Stanford, Mark; Lister, Paul (MDPI AG, Basel, Switzerland, 2015-08-07)
    Architects, designers, and engineers are making great efforts to design acoustically-efficient metal-framed walls, minimizing acoustic bridging. Therefore, efficient simulation models to predict the acoustic insulation complying with ISO 10140 are needed at a design stage. In order to achieve this, a numerical model consisting of two fluid-filled reverberation chambers, partitioned using a metal-framed wall, is to be simulated at one-third-octaves. This produces a large simulation model consisting of several millions of nodes and elements. Therefore, efficient meshing procedures are necessary to obtain better solution times and to effectively utilise computational resources. Such models should also demonstrate effective Fluid-Structure Interaction (FSI) along with acoustic-fluid coupling to simulate a realistic scenario. In this contribution, the development of a finite element frequency-dependent mesh model that can characterize the sound insulation of metal-framed walls is presented. Preliminary results on the application of the proposed model to study the geometric contribution of stud frames on the overall acoustic performance of metal-framed walls are also presented. It is considered that the presented numerical model can be used to effectively visualize the noise behaviour of advanced materials and multi-material structures.
  • Development and Characterization of Phytosterol-Enriched Oil Microcapsules for Foodstuff Application

    Tolve, Roberta; Condelli, Nicola; Can, Aygül; Tchuenbou-Magaia, Fideline Laure (Springer Link, 2017-09-30)
    Phytosterols are lipophilic compounds contained in plants and have several biological activities. The use of phytosterols in food fortification is hampered due to their high melting temperature, chalky taste, and low solubility in an aqueous system. Also, phytosterols are easily oxidized and are poorly absorbed by the human body. Formulation engineering coupled with microencapsulation could be used to overcome these problems. The aim of this study was to investigate the feasibility of encapsulating soybean oil enriched with phytosterols by spray-drying using ternary mixtures of health-promoting ingredients, whey protein isolate (WPI), inulin, and chitosan as carrier agents. The effect of different formulations and spray-drying conditions on the microencapsules properties, encapsulation efficiency, surface oil content, and oxidation stability were studied. It was found that spherical WPI-inulin-chitosan phytosterol-enriched soybean oil microcapsules with an average size below 50 μm could be produced with good encapsulation efficiency (85%), acceptable level of surface oil (11%), and water activity (0.2–0.4) that meet industrial requirements. However, the microcapsules showed very low oxidation stability with peroxide values reaching 101.7 meq O2/kg of oil just after production, and further investigations and optimization are required before any industrial application of this encapsulated system.
  • Ex-situ evaluation of PTFE coated metals in a proton exchange membrane fuel cell environment

    Baroutaji, A.; Carton, J.G.; Oladoye, A.M.; Stokes, J.; Twomey, B.; Olabi, A.G. (Elsevier, 2017-08)
    Metallic-based bipolar plates exhibit several advantages over graphite-based plates, including higher strength, lower manufacturing cost and better electrical conductivity. However, poor corrosion resistance and high interfacial contact resistance (ICR) are major challenges for metallic bipolar plates used in proton exchange membrane (PEM) fuel cells. Corrosion of metallic parts in PEM fuel cells not only increases the interfacial contact resistance but it can also decrease the proton conductivity of the Membrane Electrode Assembly (MEA), due to catalyst poisoning phenomena caused by corrosive products. In this paper, a composite coating of polytetrafluoroethylene (PTFE) was deposited on stainless steel alloys (SS304, SS316L) and Titanium (G-T2) via a CoBlast™ process. Corrosion resistance of the coated and uncoated metals in a simulated PEM fuel cell environment of 0.5 M H2SO4 + 2 ppm HF at 70 °C was evaluated using potentiodynamic polarisation. ICR between the selected metals and carbon paper was measured and used as an indicator of surface conductivity. Scanning Electron Microscopy (SEM), 3D microscopy, Energy Dispersive X-ray (EDX), X-Ray Diffraction (XRD), and contact angle measurements were used to characterise the samples. The results showed that the PTFE coating improved the hydrophobicity and corrosion resistance but increased the ICR of the coated metals due to the unconductive nature of such coating. Thus, it was concluded that it is not fully feasible to use the PTFE alone for coating metals for fuel cell applications and a hybrid coating consisting of PTFE and a conductive material is needed to improve surface conductivity.
  • Sound Transmission Loss of Light-Weight Slotted Steel Studs in a Gypsum Plasterboard Partition Wall

    Arjunan, Arun (German Acoustical Society (DEGA), 2017-08)
    Acoustic bridging through structural links is known to reduce the Sound Transmission Loss (STL) of gypsum plasterboard partition walls with steel studs. As multifamily housing become more popular, stud manufacturers are increasingly interested in improving the acoustic characteristics of steel studs to improve the sound insulation. This work is an initial attempt to understand the influence of slotted stud configurations on the sound transmission loss (STL) of partition walls. A case of partition wall commonly known as the double-leaf wall incorporating a slotted stud design is analysed experimentally and numerically based on the ISO10140 guidelines. The numerical model used for the analysis is validated using experimental test at one-third-octave bands for a frequency range of 100 to 3150 Hz. The slot configurations are designed keeping the slot to non-slot area constant to identify the effect of slot location on the acoustic and structural behaviour. The results of this study provide a better understanding of the acoustic performance of double-leaf walls that use slotted stud sections. It is considered that this can help in developing acoustically efficient stud based partition walls to reduce acoustic bridging.
  • Experimental Investigation on the Sound Reduction Performance of Frequency Controlled Acoustic Interference Cavities

    Arjunan, Arun; Stanford, Mark; Rackley, Jonathan (German Acoustical Society (DEGA), 2016-08)
    The European directives on noise reduction associated with rail, road and aviation clearly depicts the need for high efficiency sound attenuating structures for targeted noise reduction. Consequently, this paper presents key observations from Phase 1 of the UK Department of Transport (DfT) funded research project to investigate the targeted creation of acoustic interference to develop high-efficiency noise abatement structures. Geometrical cavity inspired from existing theories around Herschel-Quincke concept is experimentally investigated for the creation of frequency dependent acoustic interference. The interference cavity within a global structure was digitally conceived and prototyped using the Selective Laser Sintering (SLS) process in a Nylon 12 material. A modified impedance tube method was then used to measure the frequency dependent Sound Reduction Index (R) for a frequency range of 250 to 1600 Hz. The results showed that depending on the frequency of interest acoustic interference can be recreated by controlling the cavity length. In addition R values of 72.47 dB were observed at 900 Hz confirming the potential of the technology for high efficiency noise barriers. The observation presented in this paper establishes a new viewpoint for the use of acoustic interference for targeted noise abatement.
  • An Intelligent, Multi-Transducer Signal Conditioning Design for Manufacturing Applications

    Sillitoe, I; Button, M; Owhonda, E (Elsevier, 2017-01-24)
    This paper describes a flexible, intelligent, high bandwidth, signal conditioning reference design and implementation, which is suitable for a wide range of force and displacement transducers in manufacturing applications. The flexibility inherent in the design has allowed more than 10 specialised transducer conditioning boards to be replaced by this single design, in a range of bespoke mechanical test equipment manufactured by the authors. The board is able to automatically reconfigure itself for a wide range of transducers and calibrate and balance the transducer. The range of transducers includes LVDT, AC/DC strain gauge and inductive bridges, and a range of standard industrial voltage current interface transducers. Further, with a minor lowcost addition to the transducer connector, the board is able to recognise the type of transducer, reconfigure itself and store the calibration data within the transducer, thereafter allowing a plugand-play operation as transducers are changed. The paper provides an example of the operation in typical manufacturing test application and illustrates the stability and noise performance of the design.
  • Gas to Liquid Technology: Its Technical, Economical & Environmental Impact!

    Ogan, Deinsam D. (Lambert Academic Publishing, 2012)
    This work discusses the importance of applying Gas to Liquid Technology (GTL) in the oil rich countries. It considers its economic, technical and environmental implications, while proposing that GTL can act as alternative to flaring of natural gas (associated or stranded gas). The research further shows that this technology will boost the world economy with the influx of green petrochemical products into the market and would technically reduce the carbon foot prints of these nations.
  • Finite Element Modelling of Multipass Fusion Welding with Application to Complex Geometries

    Jiang, Wei; Yahiaoui, Kadda (Professional Engineering Publishing, 2007)
    The current paper presents recently completed work in the development of advanced multi-pass weld modelling procedures, with the ultimate objective of predicting weld residual stress distributions in thick-walled complex geometries. The modelling technique was first developed using simple three-dimensional geometries, for which experimental data was available for validation purposes. All the non-linearities associated with welding, including geometry, material, and boundary non-linearities, as well as heat source movement were taken into account. The element removal/reactivate technique was employed to simulate the deposition of filler material. Combined with a newly developed meshing technique, the model was then applied to predict residual stress distributions for a relatively thick stainless steel piping branch junction. Finally, a parametric study was conducted to assess the effects of various manufacture-related welding parameters on the final residual stress fields. The interpass temperature and cooling rate were found to be the two most sensitive parameters affecting resultant residual stresses. The residual stress profiles can be optimized relatively easily by adjusting these parameters. This research demonstrated that the developed modelling technique has potential in multi-pass welding process optimization and wide industrial applications including weld repairs.(Professional Engineering Publishing)
  • Finite Element Simulation of Multipass Welding: Full Three-Dimensional Versus Generalized Plane Strain or Axisymmetric Models

    Jiang, Wei; Yahiaoui, Kadda; Laoui, Tahar (Professional Engineering Publishing, 2005)
    A full three-dimensional (3D) thermo-mechanical finite element (FE) model has been developed to simulate the step-by-step multipass welding process. Non-linearities associated with welding, such as a moving heat source, material deposition, temperature-dependent material properties, latent heat, and large deformations, were taken into account. The model was applied to multipass butt-welded mild steel plate and girth butt-welded stainless steel pipe for validation. The simulation results were compared with independently obtained experimental data and numerical predictions from two-dimensional (2D) generalized plane strain and axisymmetric models. Good agreements between the 3D predictions and experimental data have been obtained. The computational model has the potential to be applied to multipass welded complex geometries for residual stress prediction. (Professional Engineering Publishing)
  • Finite Element Prediction of Residual Stress Distributions in a Multipass Welded Piping Branch Junction

    Jiang, Wei; Yahiaoui, Kadda (ASME (American Society of Mechanical Engineers), 2007)
    Piping branch junctions and nozzle attachments to main pressure vessels are common engineering components used in the power, oil and gas, and shipbuilding industries amongst others. These components are usually fabricated by multipass welding. The latter process is known to induce residual stresses at the fabrication stage, which can have severe adverse effects on the in-service behavior of such critical components. It is thus desirable if the distributions of residual stresses can be predicted well in advance of welding execution. This paper presents a comprehensive study of three dimensional residual stress distributions in a stainless steel tee branch junction during a multipass welding process. A full three dimensional thermomechanical finite element model has been developed for this purpose. A newly developed meshing technique has been used to model the complex intersection areas of the welded junction with all hexahedral elements. Element removal/reactivate technique has been employed to simulate the deposition of filler material. Material, geometry, and boundary nonlinearities associated with welding were all taken into account. The analysis results are presented in the form of stress distributions circumferentially along the weld line on both run and branch pipes as well as at the run and branch cross sections. In general, this computational model is capable of predicting three dimensional through-thickness welding residual stress, which can be valuable for structural integrity assessments of complex welded geometries. (ASME)
  • Evaluation of Limit Load Data for Cracked Pipe Bends under Opening Bending and Comparisons with Existing Solutions

    Yahiaoui, Kadda; Moreton, D. N.; Moffat, D. G. (Amsterdam: Elsevier, 2002)
    Most existing limit load solutions for cracked pipe bends under in-plane bending have been developed following the experimental work by Griffiths on bends with through-wall defects or by extrapolation of solutions developed for cracked straight pipes. No data exists for part-penetrating defects. This contribution summarises recently obtained experimental and finite element results from 13 tests on axially (at the crown) and circumferentially (at the intrados) cracked carbon steel pipe bends under opening bending loads. Comparisons with predictions by existing solutions for the cases investigated are reported. The solutions are shown to be excessively conservative and, on occasions, non-applicable to the cases for which they are intended. The presented data, together with results more recently made available in the open literature, could be used to form a working basis for revising the existing solutions. (Elsevier)

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