• Haar Wavelet Collocation Method for Thermal Analysis of Porous Fin with Temperature-dependent Thermal Conductivity and Internal Heat Generation

      Oguntala, George A.; Abd-Alhameed, Raed A. (2017-03-15)
      In this study, the thermal performance analysis of porous fin with temperature-dependent thermal conductivity and internal heat generation is carried out using Haar wavelet collocation method. The effects of various parameters on the thermal characteristics of the porous fin are investigated. It is found that as the porosity increases, the rate of heat transfer from the fin increases and the thermal performance of the porous fin increases. The numerical solutions by the Haar wavelet collocation method are in good agreement with the standard numerical solutions.
    • Hamiltonian modeling and structure modified control of diesel engine

      Qian, J.; Guo, Yakun; Zou, Y.; Yu, S. (2021-04)
      A diesel engine is a typical dynamic system. In this paper, a dynamics method is proposed to establish the Hamiltonian model of the diesel engine, which solves the main difficulty of con-structing a Hamiltonian function under the multi-field coupling condition. Furthermore, the control method of Hamiltonian model structure modification is introduced to study the control of a diesel engine. By means of the principle of energy-shaping and Hamiltonian model structure modification theories, the modified energy function is constructed, which is proved to be a quasi-Lyapunov function of the closed-loop system. Finally, the control laws are derived, and the simulations are carried out. The study reveals the dynamic mechanism of diesel engine operation and control and provides a new way to research the modeling and control of a diesel engine system.
    • Hand hygiene and health-care-associated infections.

      Banfield, Kathleen R.; Kerr, Kevin G.; Jones, K.A.; Snelling, Anna M. (2009-10-19)
      Despite wide acknowledgment that hand hygiene is the pre-eminent measure in the control of health-care-associated infection, Didier Pittet and colleagues 1 have highlighted that there is still a need for a systematic programme of research that will allow the development of new¿as well as refinement of existing¿approaches to hand cleansing. One of the key priorities Pittet and colleagues identified is the need for investigations into the relative importance of between and within patient cross-transmission
    • Handbook of Tissue Engineering Scaffolds: Volume one

      Mozafari, M.; Sefat, Farshid; Atala, A. (2019-06-18)
      This title provides a comprehensive and authoritative review on recent advancements in the application and use of composite scaffolds in tissue engineering. Chapters focus on specific tissue/organ (mostly on the structure and anatomy), the materials used for treatment, natural composite scaffolds, synthetic composite scaffolds, fabrication techniques, innovative materials and approaches for scaffolds preparation, host response to the scaffolds, challenges and future perspectives, and more. Bringing all the information together in one major reference, the authors systematically review and summarise recent research findings, thus providing an in-depth understanding of scaffold use in different body systems.
    • Handbook of Tissue Engineering Scaffolds: Volume two

      Mozafari, M.; Sefat, Farshid; Atala, A. (Elsevier, 2019-06-18)
      This title provides a comprehensive and authoritative review on recent advancements in the application and use of composite scaffolds in tissue engineering. Chapters focus on specific tissue/organ (mostly on the structure and anatomy), the materials used for treatment, natural composite scaffolds, synthetic composite scaffolds, fabrication techniques, innovative materials and approaches for scaffolds preparation, host response to the scaffolds, challenges and future perspectives, and more. Bringing all the information together in one major reference, the authors systematically review and summarise recent research findings, thus providing an in-depth understanding of scaffold use in different body systems.
    • Handover optimised authentication scheme for high mobility wireless multicast

      Mapoka, Trust T.; Shepherd, Simon J.; Abd-Alhameed, Raed A.; Anoh, Kelvin O.O. (2015)
      Abstract: In this paper a distributed handover optimized authentication scheme based on independent session key per access network (HOISKA) is developed for the decentralized multi-service group key management scheme over wireless mobile multicast. It enables a handover user Mi involved in multiple multicast service subscriptions to securely reuse the long term credential initially issued by the trusted authentication server (As) for deriving unique session keys per access network as it performs handover authentication across various access networks. The distributed nature of the scheme enables offloading the authentication function to the area network controllers (AKDs) such that As is not involved during handover exchange authentication signaling. This simplifies handover by reducing handover exchange signalling constituting to handover delays. Handover Access authentication (HAA) phase in HOISKA is presented then analyzed using the delay analytical model. The model proves efficacy by inducing minimum delays with less handover blocking probability while providing same level of security to the widely deployed handover authentication scheme.
    • Harmonic-suppression Using Adaptive Surface Meshing and Genetic Algorithms

      Bin-Melha, Mohammed S.; Abd-Alhameed, Raed A.; Zhou, Dawei; Zainal-Abdin, Z.B.; See, Chan H.; Elfergani, Issa T.; Excell, Peter S. (2011-03-22)
      A novel design strategy for microstrip harmonic-suppression antennas is presented. The computational method is based on an integral equation solver using adaptive surface meshing driven by a genetic algorithm. Two examples are illustrated, all involving design of coaxially-fed air-dielectric patch antennas implanted with shorting and folded walls. The characteristics of the antennas in terms of the impedance responses and far ¯eld radiation patterns are discussed theoretically and experimentally. The performances of all of the GA-optimised antennas were shown to be excellent and the presented examples show the capability of the proposed method in antenna design using GA.
    • The Haven.

      Rashid, M. Ali; Wardle, E. (Channel 4, 2005)
      The programmes follow the experiences of people living in or visiting the community. They range from a school leaver who feels she is learning more at Findhorn than she would at university to an Indian guru who offers himself as the community's new leader and wants to build a temple in the garden. A poignant backdrop to the series is the growing frailty of one of Findhorn¿s founders, 87-year-old Eileen Caddy, and the preparations, both practical and psychological, that community members are making for her death.
    • Health-risk assessment for roof-harvested rainwater via QMRA in Ikorodu area, Lagos, Nigeria

      John, Chukwuemeka K.; Pu, Jaan H.; Moruzzi, R.; Pandey, M. (IWA, 2021-09)
      This paper presents a study to assess the roof-harvested rainwater (RHRW) in the Ikorodu area of Lagos state, Nigeria, and recommends guidance to minimise the health risk for its households. The types, design and use of rainwater harvesting systems have been evaluated in the study area to inspect the human risk of exposure to Escherichia coli (E. coli). To achieve these objectives, a detailed survey involving 125 households has been conducted which showed that 25% of them drink RHRW. Quantitative microbial risk assessment (QMRA) analysis has been used to quantify the risk of exposure to harmful E. coli from RHRW utilised as potable water, based on the ingestion of 2 L of rainwater per day per capita. Results have revealed that the maximum E. coli exposure risk from the consumption of RHRW, without application of any household water treatment technique (HHTTs) and with application of alum only, were 100 and 96 respectively, for the estimated number of infection risk per 10,000 exposed households per year. This estimation has been done based on 7% of E. coli as viable and harmful. Conclusively, it is necessary that a form of disinfectant be applied to the RHRW before use.
    • Heartbeat of the Sun from Principal Component Analysis and prediction of solar activity on a millenium timescale

      Zharkova, Valentina V.; Shepherd, Simon J.; Popova, E.; Zharkov, Sergei I. (2015-10)
      We derive two principal components (PCs) of temporal magnetic field variations over the solar cycles 21–24 from full disk magnetograms covering about 39% of data variance, with σ = 0.67. These PCs are attributed to two main magnetic waves travelling from the opposite hemispheres with close frequencies and increasing phase shift. Using symbolic regeression analysis we also derive mathematical formulae for these waves and calculate their summary curve which we show is linked to solar activity index. Extrapolation of the PCs backward for 800 years reveals the two 350-year grand cycles superimposed on 22 year-cycles with the features showing a remarkable resemblance to sunspot activity reported in the past including the Maunder and Dalton minimum. The summary curve calculated for the next millennium predicts further three grand cycles with the closest grand minimum occurring in the forthcoming cycles 26–27 with the two magnetic field waves separating into the opposite hemispheres leading to strongly reduced solar activity. These grand cycle variations are probed by α − Ω dynamo model with meridional circulation. Dynamo waves are found generated with close frequencies whose interaction leads to beating effects responsible for the grand cycles (350–400 years) superimposed on a standard 22 year cycle. This approach opens a new era in investigation and confident prediction of solar activity on a millenium timescale.
    • Heat exchanger network optimization by differential evolution method

      Thuy, N.T.P.; Pendyala, R.; Rahmanian, Nejat; Marneni, N. (2014)
      The synthesis of heat exchanger network (HEN) is a comprehensive approach to optimize energy utilization in process industry. Recent developments in HEN synthesis (HENS) present several heuristic methods, such as Simulated Annealing (SA), Genetic Algorithm (GA), and Differential Evolution (DE). In this work, DE method for synthesis and optimization of HEN has been presented. Using DE combined with the concept of super-targeting, the ΔTmin optimization is determined. Then DE algorithm is employed to optimize the global cost function including the constraints, such as heat balance, the temperatures of process streams. A case study has been optimized using DE, generated structure of HEN and compared with networks obtained by other methods such as pinch technology or mathematical programming. Through the result, the proposed method has been illustrated that DE is able to apply in HEN optimization, with 16.7% increase in capital cost and 56.4%, 18.9% decrease in energy, global costs respectively.
    • Heat treatment effect on wear behaviour of HVOF-sprayed near-nanostructured coatings

      Ben Mahmud, T.; Khan, Tahir I.; Farrokhzad, M.A. (2017)
      This study investigates the effect of heat treatment on changes in microstructure and wear behaviour of WC-NiCr coatings. Two feedstock powders with a similar chemical composition and different particle sizes (near nano-structured WC-17NiCr and microstructured WC-15NiCr) were used. High-velocity oxyfuel spraying technique was used to deposit coatings on to a mild steel substrate using identical spraying parameters. Coated samples were then heat treated in a nitrogen atmosphere at 500 and 700°C. The effect of heat treatment on changes in hardness and wear performance of the coatings was studied using microstructural analysis, micro-hardness indentation and abrasive wear tests. The results showed that the heat treatment increased the hardness of both coatings and a corresponding increase in wear resistance was recorded. The formation of a brittle CrWO4 phase in the microstructured coating resulted in brittle fracture of the coating and this gave lower wear resistance compared to the nanostructured coatings.
    • Hidden labour: The skilful work of clinical audit data collection and its implications for secondary use of data via integrated health IT

      McVey, Lynn; Alvarado, Natasha; Greenhalgh, J.; Elshehaly, Mai; Gale, C.P.; Lake, J.; Ruddle, R.A.; Dowding, D.; Mamas, M.; Feltbower, R.; et al. (Springer/Biomed Central, 2021-07-16)
      Background: Secondary use of data via integrated health information technology is fundamental to many healthcare policies and processes worldwide. However, repurposing data can be problematic and little research has been undertaken into the everyday practicalities of inter-system data sharing that helps explain why this is so, especially within (as opposed to between) organisations. In response, this article reports one of the most detailed empirical examinations undertaken to date of the work involved in repurposing healthcare data for National Clinical Audits. Methods: Fifty-four semi-structured, qualitative interviews were carried out with staff in five English National Health Service hospitals about their audit work, including 20 staff involved substantively with audit data collection. In addition, ethnographic observations took place on wards, in ‘back offices’ and meetings (102 hours). Findings were analysed thematically and synthesised in narratives. Results: Although data were available within hospital applications for secondary use in some audit fields, which could, in theory, have been auto-populated, in practice staff regularly negotiated multiple, unintegrated systems to generate audit records. This work was complex and skilful, and involved cross-checking and double data entry, often using paper forms, to assure data quality and inform quality improvements. Conclusions: If technology is to facilitate the secondary use of healthcare data, the skilled but largely hidden labour of those who collect and recontextualise those data must be recognised. Their detailed understandings of what it takes to produce high quality data in specific contexts should inform the further development of integrated systems within organisations.
    • Hidden Markov models and alert correlations for the prediction of advanced persistent threats

      Ghafir, Ibrahim; Kyriakopoulos, K.G.; Lambotharan, S.; Aparicio-Navarro, F.J.; Assadhan, B.; Binsalleeh, H.; Diab, D.M. (2019-07)
      Cyber security has become a matter of a global interest, and several attacks target industrial companies and governmental organizations. The advanced persistent threats (APTs) have emerged as a new and complex version of multi-stage attacks (MSAs), targeting selected companies and organizations. Current APT detection systems focus on raising the detection alerts rather than predicting APTs. Forecasting the APT stages not only reveals the APT life cycle in its early stages but also helps to understand the attacker's strategies and aims. This paper proposes a novel intrusion detection system for APT detection and prediction. This system undergoes two main phases; the first one achieves the attack scenario reconstruction. This phase has a correlation framework to link the elementary alerts that belong to the same APT campaign. The correlation is based on matching the attributes of the elementary alerts that are generated over a configurable time window. The second phase of the proposed system is the attack decoding. This phase utilizes the hidden Markov model (HMM) to determine the most likely sequence of APT stages for a given sequence of correlated alerts. Moreover, a prediction algorithm is developed to predict the next step of the APT campaign after computing the probability of each APT stage to be the next step of the attacker. The proposed approach estimates the sequence of APT stages with a prediction accuracy of at least 91.80%. In addition, it predicts the next step of the APT campaign with an accuracy of 66.50%, 92.70%, and 100% based on two, three, and four correlated alerts, respectively.
    • High gain CPW‐fed UWB planar monopole antenna‐based compact uniplanar frequency selective surface for microwave imaging

      Abdulhasan, R.A.; Alias, R.; Ramli, K.N.; Seman, F.C.; Abd-Alhameed, Raed A. (2019-08)
      In this article, a novel uniplanar ultra‐wideband (UWB) stop frequency selective surface (FSS) was miniaturized to maximize the gain of a compact UWB monopole antenna for microwave imaging applications. The single‐plane FSS unit cell size was only 0.095λ × 0.095λ for a lower‐operating frequency had been introduced, which was miniaturized by combining a square‐loop with a cross‐dipole on FR4 substrate. The proposed hexagonal antenna was printed on FR4 substrate with coplanar waveguide feed, which was further backed at 21.6 mm by 3 × 3 FSS array. The unit cell was modeled with an equivalent circuit, while the measured characteristics of fabricated FSS array and the antenna prototypes were validated with the simulation outcomes. The FSS displayed transmission magnitude below −10 dB and linear reflection phase over the bandwidth of 2.6 to 11.1 GHz. The proposed antenna prototype achieved excellent gain improvement about 3.5 dBi, unidirectional radiation, and bandwidth of 3.8 to 10.6 GHz. Exceptional agreements were observed between the simulation and the measured outcomes. Hence, a new UWB baggage scanner system was developed to assess the short distance imaging of simulated small metallic objects in handbag model. The system based on the proposed antenna displayed a higher resolution image than the antenna without FSS.
    • A high gain multiband offset MIMO antenna based on a planar log-periodic array for Ku/K-band applications

      Fakharian, M.M.; Alibakhshikenari, M.; See, C.H.; Abd-Alhameed, Raed A. (2022-03-08)
      An offset quad-element, two-port, high-gain, and multiband multiple-input multiple-output (MIMO) planar antenna based on a log-periodic dipole array (LPDA) for Ku/K-band wireless communications is proposed, in this paper. A single element antenna has been designed starting from Carrel's theory and then optimized with a 50-Ω microstrip feed-line with two orthogonal branches that results mainly in a broadside radiation pattern and improves diversity parameters. For experimental confirmation, the designed structure is printed on an RT-5880 substrate with a thickness of 1.57 mm. The total substrate dimensions of the MIMO antenna are 55 × 45 mm2. According to the measured results, the designed structure is capable of working at 1.3% (12.82-12.98 GHz), 3.1% (13.54-13.96 GHz), 2.3% (14.81-15.15 GHz), 4.5% (17.7-18.52 GHz), and 4.6% (21.1-22.1 GHz) frequency bands. Additionally, the proposed MIMO antenna attains a peak gain of 4.2-10.7 dBi with maximum element isolation of 23.5 dB, without the use of any decoupling structure. Furthermore, the analysis of MIMO performance metrics such as the envelope correlation coefficient (ECC) and mean effective gain (MEG) validates good characteristics, and field correlation performance over the operating band. The proposed design is an appropriate option for multiband MIMO applications for various wireless systems in Ku/K-bands.
    • High orientation of long chain branched poly (lactic acid) with enhanced blood compatibility and bionic structure

      Li, Z.; Ye, L.; Zhao, X.; Coates, Philip D.; Caton-Rose, Philip D.; Martyn, Michael T. (2016-03-25)
      Highly-oriented poly (lactic acid) (PLA) with bionic micro-grooves was fabricated through solid hot drawing technology for further improving the mechanical properties and blood biocompatibility of PLA. In order to enhance the melt strength and thus obtain high orientation degree, long chain branched PLA (LCB-PLA) was prepared at first through a two-step ring-opening reaction during processing. Linear viscoelasticity combined with branch-on-branch (BOB) model was used to predict probable compositions and chain topologies of the products, and it was found that the molecular weight of PLA increased and topological structures with star like chain with three arms and tree-like chain with two generations formed during reactive processing, and consequently draw ratio as high as1200% can be achieved during the subsequent hot stretching. With the increase of draw ratio, the tensile strength and orientation degree of PLA increased dramatically. Long chain branching and orientation could significantly enhance the blood compatibility of PLA by prolonging clotting time and decreasing platelet activation. Micro-grooves can be observed on the surface of the oriented PLA which were similar to the intimal layer of blood vessel, and such bionic structure resulted from the formation of the oriented shish kebab-like crystals along the draw direction.
    • High performance on-chip array antenna based on metasurface feeding structure for terahertz integrated circuits

      Alibakhshikenari, M.; Virdee, B.S.; See, C.H.; Abd-Alhameed, Raed A.; Limiti, E. (2019-09-01)
      In this letter a novel on-chip array antenna is investigated which is based on CMOS 20μm Silicon technology for operation over 0.6-0.65 THz. The proposed array structure is constructed on three layers composed of Silicon-Ground-Silicon layers. Two antennas are implemented on the top layer, where each antenna is constituted from three sub-antennas. The sub-antennas are constructed from interconnected dual-rings. Also, the sub-antennas are interconnected to each other. This approach enhances the aperture of the array. Surface waves and substrate losses in the structure are suppressed with metallic via-holes implemented between the radiation elements. To excite the structure, a novel feeding mechanism is used comprising open-circuited microstrip lines that couple electromagnetic energy from the bottom layer to the antennas on the top-layer through metasurface slot-lines in the middle ground-plane layer. The results show the proposed on-chip antenna array has an average radiation gain, efficiency, and isolation of 7.62 dBi, 32.67%, and -30 dB, respectively.
    • High performance simulations of kernel P systems

      Bakir, M.E.; Konur, Savas; Gheorghe, Marian; Niculescu, I.M.; Ipate, F. (2014)
      The paper presents the use of a membrane computing model for specifying a synthetic biology pulse generator example and discusses some simulation results produced by the tools associated with this model and compare their performances. The results show the potential of the simulation approach over the other analysis tools like model checkers.