• Long-chain branched poly(lactic acid)- b-poly(lactide- co-caprolactone): Structure, viscoelastic behavior, and triple-shape memory effect as smart bone fixation material

      Liu, Y.; Cao, H.; Ye, L.; Coates, Philip D.; Caton-Rose, Philip D.; Zhao, X. (2020-03-11)
      A novel fully biosbased poly(lactic acid)-b-poly(lactide-co-caprolactone) (PLA-b-PLCL) with a two-phase structure and long-chain branches was specifically designed and prepared through reactive melt processing. The results showed that PLCL segments were introduced onto PLA chains successfully. With the increase of PLCL content, the blockier distribution of LA/CL chain sequences of the sample was exhibited. PLA-b-PLCL showed two distinct thermal transitions, corresponding to the glass transition of PLA and PLCL domains, respectively, whereas the phase morphology changed from a sea-island to a co-continuous structure with increasing PLCL content. Because of the long-chain branched structure, PLA-b-PLCL samples showed a much higher viscoelasticity, strong molecular entanglement, and obvious strain-hardening behavior, resulting in a high draw ratio of the sample during orientation process, whereas the tensile strength and the modulus of the oriented sample reached up to 173 MPa and 5.4 GPa, respectively, which basically met the requirements of bone screws. Moreover, PLA-b-PLCL showed a triple-shape memory effect at 55 and 120 °C, respectively. For PLA-b-30 wt % PLCL, the recovery ratio can reach up to 98.1% under 55 °C, while high mechanical properties can be maintained, realizing self-reinforcement and self-fastening effect simultaneously as a smart bone fixation material.
    • Long-term drying shrinkage of self-compacting concrete: experimental and analytical investigations

      Abdalhmid, Jamila M.; Ashour, Ashraf F.; Sheehan, Therese (2019-03-30)
      The present study investigated long-term drying shrinkage strains of self-compacting concrete (SCCs). For all SCCs mixes, Portland cement was replaced with 0–60% of fly ash (FA), fine and course aggregates were kept constant with 890 kg/m3 and 780 kg/m3, respectively. Two different water binder ratios of 0.44 and 0.33 were examined for both SCCs and normal concrete (NCs). Fresh properties of SCCs such as filling ability, passing ability, viscosity and resistance to segregation and hardened properties such as compressive and flexural strengths, water absorption and density of SCCs and NCs were also determined. Experimental results of drying shrinkage were compared to five existing models, namely the ACI 209R-92 model, BSEN-92 model, ACI 209R-92 (Huo) model, B3 model, and GL2000. To assess the quality of predictive models, the influence of various parameters (compressive strength, cement content, water content and relative humidity) effecting on the drying shrinkage strain as considered by the models are studied. The results showed that, using up to 60% of FA as cement replacement can produce SCC with a compressive strength as high as 30 MPa and low drying shrinkage strain. SCCs long-term drying shrinkage from 356 to 1000 days was higher than NCs. ACI 209R-92 model provided a better prediction of drying shrinkage compared with the other models.
    • Loop feed meander-line antenna RFID tag desing for UHF band

      Ma, Y.; Abd-Alhameed, Raed A.; Zhou, Dawei; See, Chan H.; Abidin, Z.Z.; Jin, C.; Peng, B. (2014)
      A loop feed meander-line Antenna (LFMLA) RFID tag on a relatively low dielectric constant substrate operates on the European UHF band 865-868 MHz is presented. The tag modeling is analyzed using two different electromagnetic simulator HFSS and CST. A prototype tag antenna is constructed and measured for validation. The input impedance of the proposed antenna is verified against the simulated data results, the measured and simulated results are found to be in good agreement. The compact size tag antenna shows excellent impedance matching to the typical input impedance of a RFID integrated circuit chip and a significant improvement in reading range up to 5 meters.
    • Lotus-leaf inspired surfaces: hydrophobicity evolution of replicas due to mechanical cleaning and mold wear

      Romano, J.-M.; Garcia-Giron, A.; Penchev, P.; Gülçür, Mert; Whiteside, Benjamin R.; Dimov, S. (2020-03)
      Inspired from the low wetting properties of Lotus leaves, the fabrication of dual micro/nano-scale topographies is of interest to many applications. In this research, superhydrophobic surfaces are fabricated by a process chain combining ultrashort pulsed laser texturing of steel inserts and injection moulding to produce textured polypropylene parts. This manufacturing route is very promising and could be economically viable for mass production of polymeric parts with superhydrophobic properties. However, surface damages, such as wear and abrasion phenomena, can be detrimental to the attractive wetting properties of replicated textured surfaces. Therefore, the final product lifespan is investigated by employing mechanical cleaning of textured polypropylene surfaces with multipurpose cloths following the ASTM D3450 standard. Secondly, the surface damage of replication masters after 350 injection moulding cycles with glass-fiber reinforced polypropylene, especially to intensify mould wear, was investigated. In both cases, the degradation of the dual-scale surface textures had a clear impact on surface topography of the replicas and thus on their wetting properties, too.
    • Low cost on-line non-invasive sewer flow monitoring

      Nichols, Andrew; Tait, Simon J.; Horoshenkov, Kirill V.; Shepherd, Simon J.; Zhang, Y. (2013)
      A novel acoustic sensor has been developed, capable of remotely monitoring the free surface ‘fingerprint’ of shallow flows. Temporal and spatial properties of this pattern are shown to contain information regarding the nature of the flow itself. The remote measurement can thereby be used to infer the bulk flow properties such as depth, velocity, and the hydraulic roughness of the pipe. The instrument is non-invasive and is also low cost, low maintenance, and low power. Such a device will allow for widespread monitoring of flow conditions in drainage networks, enabling pro-active maintenance and reliable real-time control.
    • Low energy pre-blended mortars: Part 1-Control of the sand drying process using a lime drying technique

      Hughes, David C.; Illingworth, J.M. (2015-12-30)
      Produttion control methods allow factory produced mortars to be supplied to a more consistent formulation than site produced mortars. However, there is scope to enhance their "sustainability" credentials by addressing the methods of drying the wet sand and the use of lower energy hydraulic components. This paper describes the development of a technique in which quicklime is added in controlled quantities to remove free water by both chemical combination and evaporation. The slaked lime so generated is porous and a third mechanism of absorption is suggested which, however, might have adverse effects during storage of the pre-blended mortar. The principal process-control factors are lime addition based upon a ratio of the stoichiometric requirements for complete slaking of the quicklime, free moisture content of the sand, mixing time of the combined sand and quicklime, and storage of the mixed material. (C) 2015 Elsevier Ltd. All rights reserved.
    • Low energy pre-blended mortars: Part 2-Production and characterisation of mortars using a novel lime drying technique

      Hughes, David C.; Illingworth, J.M.; Starinieri, V. (2015-12-30)
      The presence of free water in mortars destined for silo or bagged storage can lead to the degradation of the binder phase. Such water may be present as a result of using wet, as-delivered sand or as a consequence of prior processes such as de-activation of Roman cement. Thus, water must be removed from the system prior to storage. Part 1 of this paper describes the control of a technique by which quicklime is added to the wet system which principally dries it by both slaking the quicklime and evaporation as a consequence of the exothermic slaking reaction. Two examples of mortars are presented in which excess water is removed from the system by the inclusion of quicklime. In the first, the water is present in the as-delivered sand and the binder is a combination of the slaked lime and ggbs. In the second, the water remains after pre-hydration of a Roman cement which is a process to retard its rapid setting characteristics. It is shown that optimally dried mortars are not subject to degradation following storage of both mortar types. (C) 2015 Elsevier Ltd. All rights reserved.
    • Low-cost failure sensor design and development for water pipeline distribution systems

      Khan, Asar; Widdop, Peter D.; Day, Andrew J.; Wood, Alastair S.; Mounce, Steve R.; Machell, James (2002)
    • Low-cost process monitoring for polymer extrusion

      Deng, J.; Li, K.; Harkin-Jones, E.; Price, M.; Fei, M.R.; Kelly, Adrian L.; Vera-Sorroche, Javier; Coates, Philip D.; Brown, Elaine C. (2014)
      Polymer extrusion is regarded as an energy-intensive production process, and the real-time monitoring of both energy consumption and melt quality has become necessary to meet new carbon regulations and survive in the highly competitive plastics market. The use of a power meter is a simple and easy way to monitor energy, but the cost can sometimes be high. On the other hand, viscosity is regarded as one of the key indicators of melt quality in the polymer extrusion process. Unfortunately, viscosity cannot be measured directly using current sensory technology. The employment of on-line, in-line or off-line rheometers is sometimes useful, but these instruments either involve signal delay or cause flow restrictions to the extrusion process, which is obviously not suitable for real-time monitoring and control in practice. In this paper, simple and accurate real-time energy monitoring methods are developed. This is achieved by looking inside the controller, and using control variables to calculate the power consumption. For viscosity monitoring, a 'soft-sensor' approach based on an RBF neural network model is developed. The model is obtained through a two-stage selection and differential evolution, enabling compact and accurate solutions for viscosity monitoring. The proposed monitoring methods were tested and validated on a Killion KTS-100 extruder, and the experimental results show high accuracy compared with traditional monitoring approaches.
    • Lower and upper probabilities in the distributive lattice of subsystems

      Vourdas, Apostolos (2014-08-12)
      The set of subsystems ∑ (m) of a finite quantum system ∑(n) (with variables in Ζ(n)) together with logical connectives, is a distributive lattice. With regard to this lattice, the ℓ(m | ρn) = Tr (𝔓(m) ρn ) (where 𝔓(m) is the projector to ∑(m)) obeys a supermodularity inequality, and it is interpreted as a lower probability in the sense of the Dempster–Shafer theory, and not as a Kolmogorov probability. It is shown that the basic concepts of the Dempster–Shafer theory (lower and upper probabilities and the Dempster multivaluedness) are pertinent to the quantum formalism of finite systems.
    • LRD and SRD Traffics: Review of Results and Open Issues for the Batch Renewal Process

      Kouvatsos, Demetres D.; Fretwell, Rod J. (2002)
      The batch renewal process is the least-biased choice of process given only the measures of count correlation and interval correlation at all lags.This paper reviews the batch renewal process, both for LRD (long-range-dependent) traffic and for SRD (short-range-dependent) traffic in the discrete space-discrete time domain, and in the wider context of general traffic in that domain. It shows some applications of the batch renewal process in simple queues and in queueing network models. The paper concludes with open research problems and issues arising from the discussion.
    • A machine learning approach for ethnic classification: the British Pakistani face

      Khalid Jilani, Shelina; Ugail, Hassan; Bukar, Ali M.; Logan, Andrew J.; Munshi, Tasnim (2017)
      Ethnicity is one of the most salient clues to face identity. Analysis of ethnicity-specific facial data is a challenging problem and predominantly carried out using computer-based algorithms. Current published literature focusses on the use of frontal face images. We addressed the challenge of binary (British Pakistani or other ethnicity) ethnicity classification using profile facial images. The proposed framework is based on the extraction of geometric features using 10 anthropometric facial landmarks, within a purpose-built, novel database of 135 multi-ethnic and multi-racial subjects and a total of 675 face images. Image dimensionality was reduced using Principle Component Analysis and Partial Least Square Regression. Classification was performed using Linear Support Vector Machine. The results of this framework are promising with 71.11% ethnic classification accuracy using a PCA algorithm + SVM as a classifier, and 76.03% using PLS algorithm + SVM as a classifier.
    • Machine learning-based investigation of the association between CMEs and filaments

      Al-Omari, M.; Qahwaji, Rami S.R.; Colak, Tufan; Ipson, Stanley S. (2010-04)
      In this work we study the association between eruptive filaments/prominences and coronal mass ejections (CMEs) using machine learning-based algorithms that analyse the solar data available between January 1996 and December 2001. The Support Vector Machine (SVM) learning algorithm is used for the purpose of knowledge extraction from the association results. The aim is to identify patterns of associations that can be represented using SVM learning rules for the subsequent use in near real-time and reliable CME prediction systems. Timing and location data in the NGDC filament catalogue and the SOHO/LASCO CME catalogue are processed to associate filaments with CMEs. In the previous studies which classified CMEs into gradual and impulsive CMEs, the associations were refined based on CME speed and acceleration. Then the associated pairs were refined manually to increase the accuracy of the training dataset. In the current study, a data- mining system has been created to process and associate filament and CME data, which are arranged in numerical training vectors. Then the data are fed to SVMs to extract the embedded knowledge and provide the learning rules that could have the potential, in the future, to provide automated predictions of CMEs. The features representing the event time (average of the start and end times), duration, type and extent of the filaments are extracted from all the associated and not-associated filaments and converted to a numerical format that is suitable for SVM use. Several validation and verification methods are used on the extracted dataset to determine if CMEs can be predicted solely and efficiently based on the associated filaments. More than 14000 experiments are carried out to optimise the SVM and determine the input features that provide the best performance.
    • Maintaining QoS through preferential treatment to UMTS services

      Awan, Irfan U.; Al-Begain, Khalid (2003)
      One of the main features of the third generation (3G) mobile networks is their capability to provide different classes of services; especially multimedia and real-time services in addition to the traditional telephony and data services. These new services, however, will require higher Quality of Service (QoS) constraints on the network mainly regarding delay, delay variation and packet loss. Additionally, the overall traffic profile in both the air interface and inside the network will be rather different than used to be in today's mobile networks. Therefore, providing QoS for the new services will require more than what a call admission control algorithm can achieve at the border of the network, but also continuous buffer control in both the wireless and the fixed part of the network to ensure that higher priority traffic is treated in the proper way. This paper proposes and analytically evaluates a buffer management scheme that is based on multi-level priority and Complete Buffer Sharing (CBS) policy for all buffers at the border and inside the wireless network. The analytical model is based on the G/G/1/N censored queue with single server and R (R¿2) priority classes under the Head of Line (HoL) service rule for the CBS scheme. The traffic is modelled using the Generalised Exponential distribution. The paper presents an analytical solution based on the approximation using the Maximum Entropy (ME) principle. The numerical results show the capability of the buffer management scheme to provide higher QoS for the higher priority service classes.
    • Maintenance cost models in deregulated power systems under opportunity costs.

      Al-Arfaj, Khalid A.; Dahal, Keshav P.; Azaiez, M.N. (2007)
      Maintenance costs in deregulated power systems play an important role. This mainly includes direct costs associated with material and labor costs; and indirect costs associated with spare parts inventory, shipment, test equipment cost, indirect labor, and opportunity costs. The cost function is used as the sole or main component of the objective function in maintenance scheduling and planning activities. The cost has been modeled in literature with several representations for centralized power systems. With deregulation of power industries in many countries the costs representation to be used within the maintenance model in the decentralized power systems has become an important research question. This paper presents modeling of different components of maintenance costs that can be used within the main objective function of the maintenance scheduling and planning problem for the deregulated environment.
    • Maintenance scheduling for railway tracks under limited possession time

      Dao, Cuong D.; Basten, R.; Hartmann, A. (2018-08)
      Maintenance planning for busy railway systems is challenging because there is growing pressure on increasing operation time, which reduces the infrastructure-accessible time for maintenance. This paper proposes an optimization model that is aimed at finding the best maintenance schedule for multiple components in a railway track to minimize the total cost in the planning horizon. One distinct and practical feature of the model is that the track accessible time for maintenance is limited. We formulate all relevant costs in the component's life cycle, including maintenance cost, fixed track-closure (possession) cost, social-economic cost related to the effects of maintenance time on the train operation, and service-life shortening cost due to the shifting of activities. Generally, it is beneficial to cluster and maintain several components in a single possession because this helps reduce the cost by occupying the track only once. However, the decision must depend on the available possession time. A sensitivity analysis is performed to highlight the effects of available possession time on the number of required possessions as well as the total cost incurred.
    • Making Asset Investment Decisions for Wastewater Systems That Include Sustainability

      Ashley, R.M.; Blackwood, D.; Butler, D.; Jowitt, P.; Davies, J.; Smith, H.; Gilmour, D.; Oltean-Dumbrava, Crina (2008-03)
      Effective integrated water management is a key component of the World Water Vision and the way in which aspirations for water equity may be realized. Part of the vision includes the promotion of sustainability of water systems and full accountability for their interaction with other urban systems. One major problem is that “sustainability” remains an elusive concept, although those involved with the provision of urban wastewater systems now recognize that decisions involving asset investment should use the “triple bottom line” approach to society, the economy, and the environment. The Sustainable Water Industry Asset Resource Decisions project has devised a flexible and adaptable framework of decision support processes that can be used to include the principles of sustainability more effectively. Decision mapping conducted at the outset of the project has shown that only a narrow range of criteria currently influence the outcome of asset investment decisions. This paper addresses the concepts of sustainability assessment and presents two case studies that illustrate how multicriteria decision support systems can enhance the assessment of the relative sustainability of a range of options when decisions are being made about wastewater asset investment.
    • Making use of turbulence and its interaction with sound: a non-invasive flow monitor

      Nichols, Andrew; Horoshenkov, Kirill V.; Tait, Simon J.; Shepherd, Simon J. (2014)
      A novel acoustic sensor has been developed which is capable of remotely monitoring the free surface ‘fingerprint’ of shallow flows. The temporal and spatial properties of this fingerprint are shown to contain a wealth of information regarding the nature of the flow itself. The remote measurement can thereby be used to infer the bulk flow properties such as depth, velocity, and hydraulic roughness to within 8 % accuracy. The instrument is totally non-invasive and as such is low cost, low maintenance, and low power. Such a device will allow for widespread monitoring of flow conditions in drainage and river networks, informing flood models, and facilitating pro-active maintenance and real time control.
    • Malware Propagation Modelling in Peer-to-Peer Networks: A Review

      Musa, Ahmad S.; Al-Mohannadi, Hamad; Alhamar, J. (2018)
      Peer-to-Peer (P2P) network is increasingly becoming the most important means of trading content throughout the last years due to the constant evolvement of the cyber world. This popularity made the P2P network susceptible to the spread of malware. The detection of the cause of malware propagation is now critical to the survival of P2P networks. This paper offers a review of the current relevant mathematical propagation models that have been proposed to date to predict the propagation behavior of a malware in a P2P network. We analyzed the models proposed by researchers and experts in the field by evaluating their limitations and a possible alternative for improving the analysis of the expected behavior of a malware spread.
    • The Man Who Killed Suzy Lamplugh.

      Rashid, M. Ali; Entwhistle, C.; Jones, S. (2002)
      A reinvestigation into the unsolved murder of 25-year-old estate agent Suzy Lamplugh who went missing in 1986. Despite appeals on 'Crimewatch' and four separate investigations her killer was never found. Documentary profiles John Cannan, currently serving three life sentences for robbery, rape and murder, and who senior police officers believe to be the estate agents murderer.