• Laboratory experimental study of ocean waves propagating over a partially buried pipeline in a trench layer

      Sun, K.; Zhang, J.; Gao, Y.; Jeng, D.; Guo, Yakun; Liang, Z. (2019-02-01)
      Seabed instability around a pipeline is one of the primary concerns in offshore pipeline projects. To date, most studies focus on investigating the wave/current-induced response within a porous seabed around either a fully buried pipeline or a thoroughly exposed one. In this study, unlike previous investigations, a series of comprehensive laboratory experiments are carried out in a wave flume to investigate the wave-induced pore pressures around a partially embedded pipeline in a trench layer. Measurements show that the presence of the partially buried pipeline can significantly affect the excess pore pressure in a partially backfilled trench layer, which deviates considerably from that predicted by the theoretical approach. The morphology of the trench layer accompanied with the backfill sediments, especially the deeper trench and thicker backfill (i.e.,b≥1D,e≥0.5D), provides a certain degree of resistance to seabed instability. The amplitude of excess pore pressure around the trench layer roughly exhibits a left-right asymmetric distribution along the periphery of the pipeline, and decays sharply from the upper layer of the trench to the lower region. Deeper trench depth and thicker buried layer significantly weaken the pore-water pressures in the whole trench area, thus sheltering and protecting the submarine pipeline against the transient seabed liquefaction.
    • Laminar and turbulent analytical dam break wave modelling on dry-downstream open channel flow

      Taha, T.; Lateef, A.O.A.; Pu, Jaan H. (2018-09)
      A dam break wave caused by the discontinuity in depth and velocity of a flow is resulted from instantaneous release a body of water from a channel and classified naturally as a rapidly varied unsteady flow. Due to its nature, it is hard to be accurately represented by analytical models. The aim of this study is to establish the modelling differences and complexity echelons between analytically simulated explicit laminar and turbulent dry bed dam break wave free surface profiles. An in-depth solution to the free surface profile has been provided and evaluated by representing the reported dam break flow measurements at various locations. The methodology adopted utilizes the free surface profile formulations presented by Chanson 1,2, which are developed using the method of characteristics. In order to validate the results of the presented analytical models in illustrating the dam break wave under dry bed conditions, published experimental data provided by Schoklitsch 3, Debiane 4 and Dressler 5 are used to compare and analyze the performance of the dam break waves under laminar and turbulent flow conditions.
    • A laminar flow model of aerosol survival of epidemic and non-epidemic strains of Pseudomonas aeruginosa isolated from people with cystic fibrosis

      Clifton, I.J.; Fletcher, L.A.; Beggs, Clive B.; Denton, M.; Peckham, D.G. (2008)
      Cystic fibrosis (CF) is an inherited multi-system disorder characterised by chronic airway infection with pathogens such as Pseudomonas aeruginosa. Acquisition of P. aeruginosa by patients with CF is usually from the environment, but recent studies have demonstrated patient to patient transmission of certain epidemic strains, possibly via an airborne route. This study was designed to examine the survival of P. aeruginosa within artificially generated aerosols. Survival was effected by the solution used for aerosol generation. Within the aerosols it was adversely affected by an increase in air temperature. Both epidemic and non-epidemic strains of P. aeruginosa were able to survive within the aerosols, but strains expressing a mucoid phenotype had a survival advantage. This would suggest that segregating individuals free of P. aeruginosa from those with chronic P. aeruginosa infection who are more likely to be infected with mucoid strains may help reduce the risk of cross-infection. Environmental factors also appear to influence bacterial survival. Warming and drying the air within clinical areas and avoidance of humidification devices may also be beneficial in reducing the risk of cross-infection.
    • Landfill leachate treatment with ozone and ozone/hydrogen peroxide systems.

      Tizaoui, Chedly; Bouselmi, L.; Mansouri, L.; Ghrabi, A. (2007)
      In the search for an efficient and economical method to treat a leachate generated from a controlled municipal solid waste landfill site (Jebel Chakir) in the region of greater Tunis in Tunisia, ozone alone and ozone combined with hydrogen peroxide were studied. The leachate was characterised by high COD, low biodegradability and intense dark colour. A purpose-built reactor, to avoid foaming, was used for the study. It was found that ozone efficacy was almost doubled when combined with hydrogen peroxide at 2 g/L but higher H2O2 concentrations gave lower performances. Enhancement in the leachate biodegradability from about 0.1 to about 0.7 was achieved by the O3/H2O2 system. Insignificant changes in pH that may due to buffering effect of bicarbonate was found. A small decrease in sulphate concentrations were also observed. In contrast, chloride concentration declined at the beginning of the experiment then increased to reach its initial value. Estimates of the operating costs were made for comparison purposes and it was found that the O3/H2O2 system at 2 g/L H2O2 gave the lowest cost of about 3.1 TND (2.3 USD)/kg COD removed.
    • Large-scale data analysis using the Wigner function

      Earnshaw, Rae A.; Lei, Ci; Li, Jing; Mugassabi, Souad; Vourdas, Apostolos (2012)
      Large-scale data are analysed using the Wigner function. It is shown that the ‘frequency variable’ provides important information, which is lost with other techniques. The method is applied to ‘sentiment analysis’ in data from social networks and also to financial data.
    • Lattice-Boltzmann coupled models for advection-diffusion flow on a wide range of Péclet numbers

      Dapelo, Davide; Simonis, S.; Krause, J.J.; Bridgeman, John (Elsevier, 2021-04)
      Traditional Lattice-Boltzmann modelling of advection–diffusion flow is affected by numerical instability if the advective term becomes dominant over the diffusive (i.e., high-Péclet flow). To overcome the problem, two 3D one-way coupled models are proposed. In a traditional model, a Lattice-Boltzmann Navier–Stokes solver is coupled to a Lattice-Boltzmann advection–diffusion model. In a novel model, the Lattice-Boltzmann Navier–Stokes solver is coupled to an explicit finite-difference algorithm for advection–diffusion. The finite-difference algorithm also includes a novel approach to mitigate the numerical diffusivity connected with the upwind differentiation scheme.
    • Layered ensemble model for short-term traffic flow forecasting with outlier detection

      Abdullatif, Amr R.A.; Rovetta, S.; Masulli, F. (2016-11)
      Real time traffic flow forecasting is a necessary requirement for traffic management in order to be able to evaluate the effects of different available strategies or policies. This paper focuses on short-term traffic flow forecasting by taking into consideration both spatial (road links) and temporal (lag or past traffic flow values) information. We propose a Layered Ensemble Model (LEM) which combines Artificial Neural Networks and Graded Possibilistic Clustering obtaining an accurate forecast of the traffic flow rates with outlier detection. Experimentation has been carried out on two different data sets. The former was obtained from real UK motorway and the later was obtained from simulated traffic flow on a street network in Genoa (Italy). The proposed LEM model for short-term traffic forecasting provides promising results and given the ability for outlier detection, accuracy, robustness of the proposed approach, it can be fruitful integrated in traffic flow management systems.
    • Lean approach in a high mix, low volume manufacturing environment-case study

      Hussain, Anees; Munive-Hernandez, J. Eduardo; Campean, I. Felician (2020-03)
      Market competition is fierce and has been intensified due to globalization, therefore companies have experienced increase pressure to improve cycle and delivery times and achieve a high level of customization. Lean principles have been designed and implemented to respond to market changes. However, these principles are commonly aimed to aid low-mix high-volume (LMHV) manufacturers. This paper aims to develop a systematic approach to implement a lean framework in a high-mix low-volume (HMLV) manufacturing environment. An HMLV manufacturing environment, currently produces a variety of products which differs in terms of shape and size and different sequence of operation and as a much smaller batch size. Additionally, analysis of the manufacturing assembly shows there is a substantial variation in cycle and changeover time from product to product. In this approach, an action based study has been completed. This study uses data collection methods to be applied in order to calculate timings to be used in a Discrete Event Simulation (DES). The simulation uses lean tools to study material movement and facility layout to minimize bottlenecks and eliminate waste from the process. An introduction of lean supermarket is considered within the simulation whereby an operator withdraws products in an specific amount needed by a downstream process before introducing it across the assembly floor and an action plan is created. As a result, a lean manufacturing simulation study has been implemented to evaluate the effects of a supermarket concept within the current manufacturing environment. Initial results show a variation within the cycle and setup times for each of the different products due to the nature of the process. The paper, is limited to applying the approach to a singular production line and a singular manufacturing plant. The practical implications to implement this approach into a manufacturing environment is that there should be a need from the company. This approach should be driven by senior members within the organization as the resistance to change would increase the risk of failure. Another implication of the proposed approach is to ensure the accuracy of the data collected and to introduce a series of briefs within each stage of the approach. This is important as all stakeholders would need to be kept up-to-date with the project. However, the approach is applicable to any organization and can be applied to any sector. This paper, develops a systematic approach to implement a lean framework in a high-mix low-volume (HMLV) manufacturing environment. The approach is validated in an automotive manufacturing organization competing in global markets.
    • Learning and reuse of engineering ramp-up strategies for modular assembly systems

      Scrimieri, Daniele; Oates, R.F.; Ratchev, S.M. (2015-12)
      We present a decision-support framework for speeding up the ramp-up of modular assembly systems by learning from past experience. Bringing an assembly system to the expected level of productivity requires engineers performing mechanical adjustments and changes to the assembly process to improve the performance. This activity is time-consuming, knowledge-intensive and highly dependent on the skills of the engineers. Learning the ramp-up process has shown to be effective for making progress faster. Our approach consists of automatically capturing information about the changes made by an operator dealing with disturbances, relating them to the modular structure of the machine and evaluating the resulting system state by analysing sensor data. The feedback thus obtained on applied adaptations is used to derive recommendations in similar contexts. Recommendations are generated with a variant of the k-nearest neighbour algorithm through searching in a multidimensional space containing previous system states. Applications of the framework include knowledge transfer among operators and machines with overlapping structure and functionality. The application of our method in a case study is discussed.
    • Learning Transferable Features for Diagnosis of Breast Cancer from Histopathological Images

      Al Zorgani, Maisun M.; Irfan, Mehmood; Ugail, Hassan (2022-01)
      Nowadays, there is no argument that deep learning algorithms provide impressive results in many applications of medical image analysis. However, data scarcity problem and its consequences are challenges in implementation of deep learning for the digital histopathology domain. Deep transfer learning is one of the possible solutions for these challenges. The method of off-the-shelf features extraction from pre-trained convolutional neural networks (CNNs) is one of the common deep transfer learning approaches. The architecture of deep CNNs has a significant role in the choice of the optimal learning transferable features to adopt for classifying the cancerous histopathological image. In this study, we have investigated three pre-trained CNNs on ImageNet dataset; ResNet-50, DenseNet-201 and ShuffleNet models for classifying the Breast Cancer Histopathology (BACH) Challenge 2018 dataset. The extracted deep features from these three models were utilised to train two machine learning classifiers; namely, the K-Nearest Neighbour (KNN) and Support Vector Machine (SVM) to classify the breast cancer grades. Four grades of breast cancer were presented in the BACH challenge dataset; these grades namely normal tissue, benign tumour, in-situ carcinoma and invasive carcinoma. The performance of the target classifiers was evaluated. Our experimental results showed that the extracted off-the-shelf features from DenseNet-201 model provide the best predictive accuracy using both SVM and KNN classifiers. They yielded the image-wise classification accuracy of 93.75% and 88.75% for SVM and KNN classifiers, respectively. These results indicate the high robustness of our proposed framework.
    • Leg Length Discrepancy: A Study on In-Shoe Plantar Pressure Distribution

      Abu-Faraj, Z.O.; Abdul-Al, Mohamed; Al-Deeb, R.A. (2015-10-16)
      Leg length discrepancy (LLD) refers to the medical a condition where legs are of different lengths. This condition might affect gait and posture, and may lead to various orthopedic disorders that can have serious repercussions on the individual, be it physiological, psychological, social, economic, or ergonomic. In order to ameliorate the rehabilitation of individuals with LLD, it is imperative to understand the biomechanics of LLD in these individuals. Hence, the current study’s objective is to characterize the plantar pressures of individuals with Leg Length Discrepancy in comparison to those of asymptomatic individuals. This pilot study employs a pedar-x in-shoe pedobarograph system to gather the history of dynamic plantar pressures in one adult male individual with LLD and a representative adult normal volunteer with no diagnosed neurological or musculoskeletal disorders. The obtained results reveal quantifiable differences in the study metrics between the two individuals during walking. These results provide a proof-of-concept for this study, and may serve as diagnostic tools to better rehabilitate individuals with LLD and, thus, provide them with a better quality of life. Future work is to incorporate an extended study of 10 normal individuals versus 10 individuals with LLD, and includes both males and females, as well as both adults and adolescents.
    • Life modelling of a plastic automotive component

      Campean, I. Felician; Grove, Daniel M.; Henshall, Edwin; Rosala, George F. (2005)
      This paper presents a framework for life prediction modelling and illustrates it with a case study of a plastic automotive component subjected to competing failure mechanisms: wear, leading to a soft failure-degradation of functional performance, and fatigue, leading to loss of function through fracture of a main sub-component. The paper focuses on developing a life prediction model for the fatigue failure mechanism. Structural and kinematic analysis of the component was conducted to identify a suitable substitute load characteristic for the failure mechanism. The aim is to develop an approximate model using limited testing data and when a baseline stress-life model is not available. The issues highlighted by the case study are generic to development of life models for non-critical automotive components, thus providing potentially wide scope for practical application of the approach.
    • Linear Equalisers with Dynamic and Automatic Length Selection.

      Riera-Palou, F.; Noras, James M.; Cruickshank, D.G.M. (2001)
      A simple method for dynamically adjusting the number of taps of linear equalisers operating in unknown channel conditions is presented. Simulations with various scenarios show that the technique successfully predicts the optimum equaliser length and is capable of adjusting it as the environment changes
    • Linearization and first-order expansion of the rocking motion of rigid blocks stepping on viscoelastic foundation

      Palmeri, Alessandro; Makris, N. (2008)
      In structural mechanics there are several occasions where a linearized formulation of the original nonlinear problem reduces considerably the computational effort for the response analysis. In a broader sense, a linearized formulation can be viewed as a first-order expansion of the dynamic equilibrium of the system about a `static¿ configuration; yet caution should be exercised when identifying the `correct¿ static configuration. This paper uses as a case study the rocking response of a rigid block stepping on viscoelastic supports, whose non-linear dynamics is the subject of the companion paper, and elaborates on the challenge of identifying the most appropriate static configuration around which a first-order expansion will produce the most dependable results in each regime of motion. For the regime when the heel of the block separates, a revised set of linearized equations is presented, which is an improvement to the unconservative equations published previously in the literature. The associated eigenvalues demonstrate that the characteristics of the foundation do not affect the rocking motion of the block once the heel separates.
    • Link Budget Maximization for a Mobile-Band Subsurface Wireless Sensor in Challenging Water Utility Environments

      See, Chan H.; Abd-Alhameed, Raed A.; Atojoko, Achimugu A.; McEwan, Neil J.; Excell, Peter S. (2018-01)
      A subsurface chamber transceiver system and associated propagation channel link budget considerations for an underground wireless sensor system (UWSS) are presented: the application was a sewerage system for a water utility company. The UWSS operates over the GSM850/900, GSM1800/1900 and UMTS bands in order to operate with the standard public mobile phone system. A novel antenna was developed to minimize path loss from the underground location: a folded loop type, which is small enough to fit conveniently inside a utility manhole access chamber while giving adequate signal strength to link to mobile base stations from such a challenging environment. The electromagnetic performance was simulated and measured in both free space and in a real manhole chamber. An experimental test bed was created to determine the return loss and received signal strength with different transceiver positions below the manhole chamber access cover. Both numerical and experimental results suggested an optimum position of the unit inside the manhole, combining easy access for maintenance with viable received signal strength. This confirmed that the characteristics were adequate for incorporation in a transceiver designed to communicate with mobile base stations from underground. A field trial confirmed the successful operation of the system under severe conditions.
    • Liquid level monitoring using passive RFID tags

      Atojoko, Achimugu A.; Bin-Melha, Mohammed S.; Elkhazmi, Elmahdi A.; Usman, Muhammad; Abd-Alhameed, Raed A.; See, Chan H. (2013)
      Tank flooding have become major causes of pollution both in residential and industrial areas majorly caused by overflows of water(mostly residential) and volatile poisonous industrial liquids from the storage tanks. An effective way of avoiding this problem will be by deploying some mechanism to monitor liquid level at each point in time and escalating unusual liquid levelsto a pump control circuit or to the relevant authorities for prompt action to avoid a flooding occurrence. This paper presents a low cost power efficient liquid level monitoring technique. Passive RFID tags are designed modelled and deployed, the signal variation from the Alien Reader Software are used to effectively estimate the level of liquid in any surface or underground tank. The experimental set up is presented and an expository presentation is made of the passive tag design, modelled and simulated and adopted for same application.
    • Load capacity of reinforced concrete continuous deep beams

      Yang, Keun-Hyeok; Ashour, Ashraf F. (2008)
      Most codes of practice, such as EC2 and ACI 318-05, recommend the use of strut-and-tie models for the design of reinforced concrete deep beams. However, studies on the validity of the strut-and-tie models for continuous deep beams are rare. This paper evaluates the strut-and-tie model specified by ACI 318-05 and mechanism analysis of the plasticity theory in predicting the load capacity of 75 reinforced concrete continuous deep beams tested in the literature. The influence of such main parameters as compressive strength of concrete, shear span-to-overall depth ratio, main longitudinal bottom reinforcement, and shear reinforcement on the load capacity is also investigated using both methods and experimental results. Experimental results were closer to the predictions obtained from the mechanism analysis than the strut-and-tie model. The strut-and-tie model highly overestimated the load capacity of continuous deep beams without shear reinforcement.
    • Load capacity predictions of continuous concrete deep beams reinforced with GFRP bars

      Shalookh, Othman H. Zinkaah; Ashour, Ashraf F. (2019-06)
      Nine continuous concrete deep beams reinforced with glass fibre reinforced polymer (GFRP) bars were experimentally tested to failure. Three main parameters were investigated, namely, shear span-to-overall depth ratio, web reinforcement and size effect. The experimental results confirmed the impacts of web reinforcement and size effect that were not considered by the strut-and-tie method (STM) of the only code provision, the Canadian S806-12, that addressed such elements. The experimental results were employed to evaluate the applicability of the methods suggested by the American, European and Canadian codes as well as the previous studies to predict the load capacities of continuous deep beams reinforced with GFRP bars. It was found that these methods were unable to reflect the influences of size effect and/or web reinforcement, the impact of which has been confirmed by the current experimental investigation. Therefore, a new effectiveness factor was recommended to be used with the STM. Additionally, an upper-bound analysis was developed to predict the load capacity of the tested specimens considering a reduced bond strength of GFRP bars. A good agreement between the predicted results and the experimental ones was obtained with the mean and coefficient of variation values of 1.02 and 5.9%, respectively, for the STM and 1.03 and 8.6%, respectively, for the upper-bound analysis.
    • Load-aware radio access selection in future generation wireless networks

      Ali, Muhammad; Pillai, Prashant; Hu, Yim Fun (2013)
      In the telecommunication networks the introduction of Next Generation Wireless Networks (NGWN) has been described as the most significant change in wireless communication. The convergence of different access networks in NGWN allows generalized mobility, consistency and ubiquitous provision of services to mobile users. The general target of NGWN is to transport different types of information like voice, data, and other media like video in packets form like IP. The NGWNs offer significant savings in costs to the operators along with new and interesting services to the consumers. Major challenges in NGWN are efficient resource utilization, maintaining service quality, reliability and the security. This paper proposes a solution for seamless load aware Radio Access Technology (RAT) selection based on interworking of different RATs in NGWN. In this paper novel load balancing algorithms have been proposed which have been simulated on the target network architecture for TCP data services. The IEEE 802.21 Media Independent Handover (MIH) is utilized in load balancing specifically for mobility management, which enable low handover latency by reducing the target network detection time. The proposed method considers the network type, signal strength, data rate and network load as primary decision parameters for RAT selection process and consists of two different algorithms, one located in the mobile terminal and the other at the network side. The network architecture, the proposed load balancing framework and RAT selection algorithms were simulated using NS2. Different attributes like load distribution in the wireless networks and average throughput to evaluate the effects of load balancing in considered scenarios.
    • Localised Credit Based QoS Routing.

      Alabbad, Saad H.; Woodward, Mike E. (2006)
      Localized Quality of Service (QoS) routing has recently been proposed as a viable alternative approach to traditional QoS routing algorithms that use global state information. In this approach, problems associated with maintaining global state information and the staleness of such information are avoided by having the source nodes to infer the network QoS state based on flow blocking statistics collected locally, and perform flow routing using this localized view of the network QoS state . In this paper we introduce a credit based routing algorithm (cbr) which is a simple yet effective localized QoS routing algorithm. We compare its performance against the localized proportional sticky routing (psr) algorithm same time complexity. using different types of network topologies, QoS requirements and traffic patterns and under a wide range of traffic loads. Extensive simulations show that our algorithm outperforms the psr algorithm with the same time complexity.