Recent Submissions

  • Evaluation of bandwidth management technique using dynamic LSP tunnelling and LDP in MPLS for sustainable mobile wireless networks

    Mustapha, O.Z.; Hu, Yim Fun; Sheriff, Ray E.; Abd-Alhameed, Raed A.; Ali, M. (2020-03)
    Fairness in bandwidth resource allocation is highly significance to the advancement of the future generation mobile and wireless technologies. It is likely that restriction of bandwidth due to the employment of some scheduling scheme would not be an appropriate option for the future development of communication systems. However, there is need to consider an implementation that would lead to good network performance and avoid unguaranteed bandwidth delivery. This paper focusses on evaluating the performance of Bandwidth Allocation using Dynamic Label Switching Paths (LSPs) Tunnelling and Label Distribution Protocol (LDP) signalling in Multi-Protocol Label Switching (MPLS) network. This will make provision for bandwidth allocation and reservation possible. An appropriate bandwidth allocation would have a positive impact on throughput as well as the delay. The results of an IP (Internet Protocol) Network without MPLS enabled is compared with MPLS model network. Furthermore, implementation of dynamic and static LSPs models are presented with about 75% decrease in packet delay variation for dynamic LSP when compared from static LSP. In addition, the models of bandwidth estimation, bandwidth allocation, delay and jitter are provided. Performance metrics used in this respect for multimedia services (Voice and Video conferencing) confirm that the modified models are improved in comparison with the baseline, having highest throughput of about 51% increment, and packet delay variation decreases drastically.
  • Dual-Polarized Highly Folded Bowtie Antenna with Slotted Self-Grounded Structure for Sub-6 GHz 5G Applications

    Alibakhshikenari, M.; Virdee, B.S.; See, C.H.; Shukla, P.; Moghaddam, S.M.; Zaman, A.U.; Shafqaat, S.; Akinsolu, M.O.; Liu, B.; Yang, J.; et al. (IEEE, 2021)
    In this paper, a novel dual-polarized highly-folded self-grounded Bowtie antenna that is excited through I-shaped slots is proposed for applications in sub-6GHz 5G multiple-input-multiple-output (MIMO) antenna systems. The antenna consists of two pairs of folded radiation petals whose base is embedded in a double layer of FR-4 substrate with a common ground-plane which is sandwiched between the two substrate layers. The ground-plane is defected with two I-shaped slots located under the radiation elements. Each pair of radiation elements are excited through a microstrip line on the top layer with RF signal that is 180° out of phase with respect to each other. The RF signal is coupled to the pair of feedlines on the top layer through the I-shaped slots from the two microstrip feedlines on the underside of the second substrate. The proposed feed mechanism gets rid of the otherwise bulky balun. The Bowtie antenna is a compact solution with dimensions of 32×32×33.8 mm3. Measured results have verified that the antenna operates over a frequency range of 3.1–5 GHz and exhibits an average gain and antenna efficiency in the vertical and horizontal polarizations of 7.5 dBi and 82.6%, respectively.
  • Quantum ReLU activation for Convolutional Neural Networks to improve diagnosis of Parkinson’s disease and COVID-19

    Parisi, Luca; Neagu, Daniel; Ma, R.; Campean, I. Felician (Elsevier, 2022-01)
    This study introduces a quantum-inspired computational paradigm to address the unresolved problem of Convolutional Neural Networks (CNNs) using the Rectified Linear Unit (ReLU) activation function (AF), i.e., the ‘dying ReLU’. This problem impacts the accuracy and the reliability in image classification tasks for critical applications, such as in healthcare. The proposed approach builds on the classical ReLU and Leaky ReLU, applying the quantum principles of entanglement and superposition at a computational level to derive two novel AFs, respectively the ‘Quantum ReLU’ (QReLU) and the ‘modified-QReLU’ (m-QReLU). The proposed AFs were validated when coupled with a CNN using seven image datasets on classification tasks involving the detection of COVID-19 and Parkinson’s Disease (PD). The out-of-sample/test classification accuracy and reliability (precision, recall and F1-score) of the CNN were compared against those of the same classifier when using nine classical AFs, including ReLU-based variations. Findings indicate higher accuracy and reliability for the CNN when using either QReLU or m-QReLU on five of the seven datasets evaluated. Whilst retaining the best classification accuracy and reliability for handwritten digits recognition on the MNIST dataset (ACC = 99%, F1-score = 99%), avoiding the ‘dying ReLU’ problem via the proposed quantum AFs improved recognition of PD-related patterns from spiral drawings with the QReLU especially, which achieved the highest classification accuracy and reliability (ACC = 92%, F1-score = 93%). Therefore, with these increased accuracy and reliability, QReLU and m-QReLU can aid critical image classification tasks, such as diagnoses of COVID-19 and PD.
  • Estimation of structural steel and concrete stocks and flows at urban scale–towards a prospective circular economy

    Ajayebi, A.; Hopkinson, P.; Zhou, Kan; Lam, Dennis; Chen, H-M.; Wang, Y. (2021-11)
    Quantification of stocks and flows of construction materials is a key first stage in assessing the potential for creating higher value at end-of-life decisions compared to destructive demolition. Steel and concrete are amongst the most widely used construction materials primarily in structural components. Such components are highly variable in design, type, and dimensions. In the absence of urban-scale digitised models of structural components or building plans, accurate assessment relies on either onsite inspection or modelling by material intensity (MI) co-efficient which can vary by up to a factor of 100. In this study, we extend previous stock modelling approaches through the development of a method that relies on building archetypes and produces MI coefficients of steel and concrete that are representative of frame types, temporally explicit and disaggregated at product level. This is compared to the common existent method of calculating MI to demonstrate the capabilities of the proposed method. Coupled with a spatiotemporal model of urban buildings, the developed MI of both methods are applied to a case study in the UK. The total in-use stock of steel and concrete within multi-storey buildings is estimated at 81,000 tonnes and 655,000 m3 respectively. The stocks of steel and concrete are disaggregated based on their functions as products, for instance steel beams are distinguished from reinforcement steel. Subsequently, the embodied carbon of the in-use stock is calculated as 350 kt CO2eq. The results show the proposed method enables a more granular assessment of the embodied carbon of the structural material quantities.
  • New composite flooring system for the circular economy

    Lam, Dennis; Yang, Jie; Wang, Yong; Dai, Xianghe; Sheehan, Therese; Zhou, Kan (Techno-Press, 2021-09-10)
    Circular economy is an economic system aimed at minimizing wastes and making the most of the current resources. This regenerative approach contrasts with the traditional linear economy, which has been adopted by the construction industry. Developing new construction technologies for sustainable built environment is a top priority for the construction industry throughout the world. Much of the environmental impact from the construction industry is associated with the consumption of resources and generation of waste. The construction industry in Europe consumes over 70,000 million tonnes of materials each year and generates over 250 million tonnes of waste. Composite flooring formed by connecting the concrete slabs to the supporting steel beams has been widely used for many years and is well established as one of the most efficient floor systems in multi storey steel frame building structures. However, shear connectors are welded through the steel decking to the steel beams and cast into the concrete; this made deconstruction and reuse of these components almost impossible. A new composite flooring system which allows for the reuse of the steel beams and composite floor slabs is developed and tested to assess its potential and suitability for reuse. This paper presents the results of a series of full scale beam tests and demonstrates the reusability of this new form of composite flooring systems. Simplified hand calculations are also provided and compared against beam tests
  • Toward full-stack in silico synthetic biology: integrating model specification, simulation, verification, and biological compilation

    Konur, Savas; Mierla, L.M.; Fellermann, H.; Ladroue, C.; Brown, B.; Wipat, A.; Twycross, J.; Dun, B.P.; Kalvala, S.; Gheorghe, Marian; et al. (2021-08-02)
    We present the Infobiotics Workbench (IBW), a user-friendly, scalable, and integrated computational environment for the computer-aided design of synthetic biological systems. It supports an iterative workflow that begins with specification of the desired synthetic system, followed by simulation and verification of the system in high- performance environments and ending with the eventual compilation of the system specification into suitable genetic constructs. IBW integrates modelling, simulation, verification and bicompilation features into a single software suite. This integration is achieved through a new domain-specific biological programming language, the Infobiotics Language (IBL), which tightly combines these different aspects of in silico synthetic biology into a full-stack integrated development environment. Unlike existing synthetic biology modelling or specification languages, IBL uniquely blends modelling, verification and biocompilation statements into a single file. This allows biologists to incorporate design constraints within the specification file rather than using decoupled and independent formalisms for different in silico analyses. This novel approach offers seamless interoperability across different tools as well as compatibility with SBOL and SBML frameworks and removes the burden of doing manual translations for standalone applications. We demonstrate the features, usability, and effectiveness of IBW and IBL using well-established synthetic biological circuits.
  • Applications of Biocatalysts for Sustainable Oxidation of Phenolic Pollutants: A Review

    Salehi, S.; Abdollahi, K.; Panahi, R.; Rahmanian, Nejat; Shakeri, M.; Mokhtarani, B. (MDPI, 2021-08-02)
    Phenol and its derivatives are hazardous, teratogenic and mutagenic, and have gained significant attention in recent years due to their high toxicity even at low concentrations. Phenolic compounds appear in petroleum refinery wastewater from several sources, such as the neutralized spent caustic waste streams, the tank water drain, the desalter effluent and the production unit. Therefore, effective treatments of such wastewaters are crucial. Conventional techniques used to treat these wastewaters pose several drawbacks, such as incomplete or low efficient removal of phenols. Recently, biocatalysts have attracted much attention for the sustainable and effective removal of toxic chemicals like phenols from wastewaters. The advantages of biocatalytic processes over the conventional treatment methods are their ability to operate over a wide range of operating conditions, low consumption of oxidants, simpler process control, and no delays or shock loading effects associated with the start-up/shutdown of the plant. Among different biocatalysts, oxidoreductases (i.e., tyrosinase, laccase and horseradish peroxidase) are known as green catalysts with massive potentialities to sustainably tackle phenolic contaminants of high concerns. Such enzymes mainly catalyze the o-hydroxylation of a broad spectrum of environmentally related contaminants into their corresponding o-diphenols. This review covers the latest advancement regarding the exploitation of these enzymes for sustainable oxidation of phenolic compounds in wastewater, and suggests a way forward.
  • A New Optimization Algorithm Based on the Fungi Kingdom Expansion Behavior for Antenna Applications

    Alnahwi, F.M.; Al-Yasir, Y.I.A.; Sattar, D.; Ali, R.S.; See, C.H.; Abd-Alhameed, Raed A. (MDPI, 2021-08-26)
    This paper presents a new optimization algorithm based on the behavior of the fungi kingdom expansion (FKE) to optimize the radiation pattern of the array antenna. The immobile mass ex-pansion of the fungi is mimicked in this work as a chaotic behavior with a sinusoidal map func-tion, while the mobile mass expansion is realized by a linear function. In addition, the random germination of the spores is utilized for randomly distributing the variables that are far away from the best solution. The proposed FKE algorithm is applied to optimize the radiation pattern of the antenna array, and then its performance is compared with that of some well-known algo-rithms. The MATLAB simulation results verify the superiority of the proposed algorithm in solving 20-element antenna array problems such as sidelobe reduction with sidelobe ratio (SLR = 25.6 dB), flat-top pattern with SLR = 23.5 dB, rectangular pattern with SLR = 19 dB, and an-ti-jamming systems. The algorithm also results in a 100% success rate for all of the mentioned antenna array problems
  • Ultra-Compact mm-Wave Monolithic IC Doherty Power Amplifier for Mobile Handsets

    Sajedin, M.; Elfergani, Issa T.; Rodriguez, Jonathan; Abd-Alhameed, Raed A.; Fernandez-Barciela, M.; Violas, M. (MDPI, 2021-09)
    This work develops a novel dynamic load modulation Power Amplifier (PA) circuity that can provide an optimum compromise between linearity and efficiency while covering multiple cellular frequency bands. Exploiting monolithic microwave integrated circuits (MMIC) technology, a fully integrated 1W Doherty PA architecture is proposed based on 0.1 µm AlGaAs/InGaAs Depletion- Mode (D-Mode) technology provided by the WIN Semiconductors foundry. The proposed wideband DPA incorporates the harmonic tuning Class-J mode of operation, which aims to engineer the voltage waveform via second harmonic capacitive load termination. Moreover, the applied post-matching technique not only reduces the impedance transformation ratio of the conventional DPA, but also restores its proper load modulation. The simulation results indicate that the monolithic drive load modulation PA at 4 V operation voltage delivers 44% PAE at the maximum output power of 30 dBm at the 1 dB compression point, and 34% power-added efficiency (PAE) at 6 dB power back-off (PBO). A power gain flatness of around 14 ± 0.5 dB was achieved over the frequency band of 23 GHz to 27 GHz. The compact MMIC load modulation technique developed for the 5G mobile handset occupies the die area of 3.2.
  • Toward Improving Confidence in Autonomous Vehicle Software: A Study on Traffic Sign Recognition Systems

    Aslansefat, K.; Kabir, Sohag; Abdullatif, Amr R.A.; Vasudevan, Vinod; Papadopoulos, Y. (IEEE, 2021-08)
    This article proposes an approach named SafeML II, which applies empirical cumulative distribution function-based statistical distance measures in a designed human-in-the loop procedure to ensure the safety of machine learning-based classifiers in autonomous vehicle software. The application of artificial intelligence (AI) and data-driven decision-making systems in autonomous vehicles is growing rapidly. As autonomous vehicles operate in dynamic environments, the risk that they can face an unknown observation is relatively high due to insufficient training data, distributional shift, or cyber-security attack. Thus, AI-based algorithms should make dependable decisions to improve their interpretation of the environment, lower the risk of autonomous driving, and avoid catastrophic accidents. This paper proposes an approach named SafeML II, which applies empirical cumulative distribution function (ECDF)-based statistical distance measures in a designed human-in-the-loop procedure to ensure the safety of machine learning-based classifiers in autonomous vehicle software. The approach is model-agnostic and it can cover various machine learning and deep learning classifiers. The German Traffic Sign Recognition Benchmark (GTSRB) is used to illustrate the capabilities of the proposed approach.
  • Flyback photovoltaic micro-inverter with a low cost and simple digital-analog control scheme

    Yaqoob, S.J.; Obed, A.; Zubo, R.; Al-Yasir, Yasir; Fadhel, H.; Mokryani, Geev; Abd-Alhameed, Raed A. (MDPI, 2021-07)
    The single-stage flyback Photovoltaic (PV) micro-inverter is considered as a simple and small in size topology but requires expensive digital microcontrollers such as Field-Programmable Gate Array (FPGA) or Digital Signal Processor (DSP) to increase the system efficiency, this would increase the cost of the overall system. To solve this problem, based on a single-stage flyback structure, this paper proposed a low cost and simple analog-digital control scheme. This control scheme is implemented using a low cost ATMega microcontroller built in the Arduino Uno board and some analog operational amplifiers. First, the single-stage flyback topology is analyzed theoretically and then the design consideration is obtained. Second, a 120 W prototype was developed in the laboratory to validate the proposed control. To prove the effectiveness of this control, we compared the cost price, overall system efficiency, and THD values of the proposed results with the results obtained by the literature. So, a low system component, single power stage, cheap control scheme, and decent efficiency are achieved by the proposed system. Finally, the experimental results present that the proposed system has a maximum efficiency of 91%, with good values of the total harmonic distortion (THD) compared to the results of other authors
  • Diagnostics and prognostics for complex systems: A review of methods and challenges

    Soleimani, Morteza; Campean, I. Felician; Neagu, Daniel (2021)
    Diagnostics and prognostics have significant roles in the reliability enhancement of systems and are focused topics of active research. Engineered systems are becoming more complex and are subjected to miscellaneous failure modes that impact adversely their performability. This everincreasing complexity makes fault diagnostics and prognostics challenging for the system-level functions. A significant number of successes have been achieved and acknowledged in some review papers; however, these reviews rarely focused on the application of complex engineered systems nor provided a systematic review of diverse techniques and approaches to address the related challenges. To bridge the gap, this paper firstly presents a review to systematically cover the general concepts and recent development of various diagnostics and prognostics approaches, along with their strengths and shortcomings for the application of diverse engineered systems. Afterward, given the characteristics of complex systems, the applicability of different techniques and methods that are capable to address the features of complex systems are reviewed and discussed, and some of the recent achievements in the literature are introduced. Finally, the unaddressed challenges are discussed by taking into account the characteristics of automotive systems as an example of complex systems. In addition, future development and potential research trends are offered to address those challenges. Consequently, this review provides a systematic view of the state of the art and case studies with a reference value for scholars and practitioners.
  • 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.
  • Green and Highly Efficient MIMO Transceiver System for 5G Heterogenous Networks

    Al-Yasir, Yasir; Abdulkhaleq, Ahmed M.; Parchin, Naser O.; Elfergani, Issa T.; Rodriguez, J.; Noras, James M.; Abd-Alhameed, Raed A.; Rayit, A.; Qahwaji, Rami (IEEE, 2021-07-27)
    The paper presents the general requirements and an exemplary design of the RF front-end system that in today´s handset is a key consumer of power. The design is required to minimize the carbon footprint in mobile handsets devices, whilst facilitating cooperation, and providing the energy-efficient operation of multi-standards for 5G communications. It provides the basis of hardware solutions for RF front-end integration challenges and offers design features covering energy efficiency for power amplifiers (PAs), Internet of Things (IoT) controlled tunable filters and compact highly isolated multiple-input and multiple-output (MIMO) antennas. An optimum design requires synergetic collaboration between academic institutions and industry in order to satisfy the key requirements of sub-6 GHz energy-efficient 5G transceivers, incorporating energy efficiency, good linearity and the potential for low-cost manufacturing. A highly integrated RF transceiver was designed and implemented to transmit and receive a picture using compact MIMO antennas integrated with efficient tunable filters and high linearity PAs. The proposed system has achieved a bit error rate (BER) of less than 10-10 at a data rate of 600 Mb/s with a wireless communication distance of more than 1 meter and power dissipation of 18-20 mW using hybrid beamforming technology and 64-QAM modulation.
  • Investigating the compatibility of nickel coated carbon nanotubes and cementitious composites through experimental evidence and theoretical calculations

    Wang, D.; Dong, S.; Wang, X.; Ashour, Ashraf F.; Lv, X.; Han, B. (2021-09)
    Nickel coated multi-walled carbon nanotubes (NiMCNTs) are favorable reinforcing nanofillers for modifying cementitious composites due to their preeminent mechanical properties, electrical conductivity, thermal properties and dispersibility. This paper investigates the mechanical properties and compatibility of NiMCNTs filled cementitious composites, having two different types of cement, two water to cement ratios, and two dosages of five types of NiMCNTs. The results show that 0.06 vol.% NiMCNTs with small aspect ratios can significantly enhance the mechanical properties of cementitious composites, while NiMCNTs with large aspect ratios play a better strengthening effect at 0.03 vol.%. The flexural strength/toughness of cementitious composites containing 0.06 vol.% NiMCNTs with an aspect ratio of 200 can be increased by 19.65%/116.78%. Adding 0.03 vol.% NiMCNTs with an aspect ratio of 1000 enhances the compressive strength/toughness of composites by 18.61%/47.44%. Besides, NiMCNTs have preferable compatibility to cementitious composites prepared by P·O 42.5R cement with a water to cement ratio of 0.3. The enhancement mechanism is related to the denser microstructure and effective suppression of microcracks in the cementitious matrix by NiMCNTs with filling, bridging and pull-out effects, as well as the high interface bond strength between NiMCNTs and matrix. A strength prediction model for NiMCNTs reinforced cementitious composites is also established to estimate the mechanical strength of cementitious composites containing NiMCNTs with different aspect ratios/contents, showing a small relative error within ±6%/±13% for predicted flexural/compressive strength values in comparison with the experimental results.
  • Tranquillity trails – design, implementation and benefits for healthy leisure

    Watts, Gregory R.; Bauer, J. (Taylor and Francis, 2021)
    Tranquillity trails (TTs) are designed to provide a quiet and peaceful walk through mainly leafy lanes and roads and connect green open spaces where visitors can stop for thought and relaxation. There are numerous health benefits from being in close proximity to nature and TTs can facilitate this contact in mainly urban areas. This study involved the design of a trail in Tramore, a coastal town in south east Ireland. The trail links an old coastguard station, now converted to a cultural centre and coffee shop, with a Japanese garden. The trail includes a coastal path with fine views across a bay, wooded areas as well as leafy residential streets. The design of the trail was facilitated by the use of a previous developed tranquillity rating prediction tool (TRAPT) that involved the estimation of the level of man-made noise and the percentage of natural features in view. Participants who had completed the whole of the trail were encouraged to complete a questionnaire to gauge any benefits. As expected, it was reported that there were increased levels of relaxation and reduced stress. It was concluded that the approach can be used elsewhere to improve the well-being of residents and visitors.
  • Bond behaviors between nano-engineered concrete and steel bars

    Wang, X.; Dong, S.; Ashour, Ashraf F.; Ding, S.; Han, B. (Elsevier, 2021-09)
    This paper investigated the bond characteristics between eight types of nanofillers modified reactive powder concrete (RPC) and plain steel bars, aiming to explore the modifying mechanisms and establish a bond-slip relationship model for nanofillers modified RPC and steel bar interface. The experimental results indicated that the incorporation of nanofillers can increase the bond strength and reduce the slip between RPC and plain steel bars. It was shown that a 2.15 MPa/20.5% of absolute/relative increase in cracking bond strength, a 1.25 MPa/10.3% of absolute/relative increase in ultimate bond strength, a 2.35 MPa/22.4% of absolute/relative increase in residual bond strength, a 0.592 mm/56.5% of absolute/relative reduction in ultimate bond slip, and a 1.779 mm/52.1% of absolute/relative reduction in residual bond slip were the best achieved due to the addition of various nanofillers. The enhancement of nanofillers on RPC-steel bar interface has been mainly attributed to RPC microstructure improvement, optimization of intrinsic compositions, and elimination of defects in the interface, especially the underside near steel bar, due to the nano-core effect of nanofillers enriched in the interface. In addition, the bond-slip relationship of nanofillers modified RPC-steel bar interface can be accurately described by the proposed model considering an initial branch.
  • Energy-harvesting concrete for smart and sustainable infrastructures

    Wang, X.; Dong, S.; Ashour, Ashraf F.; Han, B. (A Springer Nature Publication, 2021)
    Concrete with smart and functional properties (e.g., self-sensing, self-healing, and energy-harvesting) represents a transformative direction in the field of construction materials. Energy-harvesting concrete has the capability to store or convert the ambient energy (e.g., light, thermal, and mechanical energy) for feasible uses, alleviating global energy and pollution problems as well as reducing carbon footprint. The employment of energy-harvesting concrete can endow infrastructures (e.g., buildings, railways, and highways) with energy self-sufficiency, effectively promoting sustainable infrastructure development. This paper provides a systematic overview on the principles, fabrication, properties, and applications of energy-harvesting concrete (including light-emitting, thermal-storing, thermoelectric, pyroelectric, and piezoelectric concretes). The paper concludes with an outline of some future challenges and opportunities in the application of energy-harvesting concrete in sustainable infrastructures.
  • Flow analysis of melted urea in a perforated rotating bucket

    Muhammad, A.; Rahmanian, Nejat; Pendyala, R. (2013-10)
    A comprehensive study of the internal flow field for the prilling application in a perforated rotating bucket has been carried out. Computational Fluid Dynamics (CFD) is used to investigate the flow field of urea melt inside the perforated rotating bucket. The bucket is mounted at the top of the prilling tower. In prilling process, urea melt is sprayed by the perforated rotating bucket to produce the urea droplets, which falls down due to gravity. These drops fall down through a cooling medium and solidify into prills. The velocity field in the bucket is very important to study, as it has great effect on the heat and mass transfer performance in prilling process. ANSYS 14.0 CFD package is used to simulate and Design Modeler and Catia V5 are used for geometrical model of the perforated prilling bucket. Velocity distribution on different planes are obtained and discussed.
  • 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.

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