• Behaviour of inclined, tapered and STS square CFST stub columns subjected to axial load

      Lam, Dennis; Dai, Xianghe; Han, L-H.; Ren, Q-X.; Li, W. (2012)
      This paper describes the finite element method using ABAQUS to model the axial compressive behaviour of inclined, tapered and straight-tapered-straight (STS) concrete filled steel tubular stub (CFST) columns with square hollow sections. The accuracy of the numerical model was verified by comparing the numerical predictions with experimental study of the 200×200×3.75 RHS filled with C60 concrete with inclined angle of 0-9° and tapered angle of 0-4°. The results show that the compressive behaviours, load vs. strain relationship and failure mode predicted by the numerical simulations were agreeable with experimental results. After the validation, a parametric study was performed with 3 typical steel hollow sections (200×200×3.75 RHS, 300×300×6.3 RHS and 400×400×8.0 RHS) and extended the inclined angle and tapered angle to 0-15° and 0-12° respectively. The parametric study highlights some of the behaviour observed in test and extends the application range. In addition, reduction factor for calculating the axial capacity of this form of CFST columns are proposed.
    • Behaviour of interlocking mortarless hollow block walls under in-plane loading

      Safiee, N.A.; Nasir, N.A.M.; Ashour, Ashraf F.; Bakar, N.A. (2018-01)
      Experimental study of five full scale masonry wall panels subjected to prescibed pre-compressive vertical loading and increasing in-plane lateral loading is discussed. All five walls were constructed using interlocking mortarless load bearing hollow concrete blocks. The behaviour of wall in term of deflections along the wall height, shear strength, mortarless joint behaviour and local and overall failures under increasing in-plane lateral loading and pre-compressive vertical loading are reported and analysed. Simple strut-and-tie models are also developed to estimate the ultimate in-plane lateral capacity of the panel walls tested. The results indicate that, as the pre-compressive load increases, the in-plane lateral load capacity of walls increases. All walls tested failed due to diagonal shear and/or moderate toe crushing depending on the level of the pre-compressive load. The proposed strut-and-tie models were able to give reasonable predictions of the walls tested.
    • Behaviour of normal and high strength concrete-filled compact steel tube circular stub columns.

      El-Lobody, E.; Young, B.; Lam, Dennis (2006)
      This paper presents the behaviour and design of axially loaded concrete-filled steel tube circular stub columns. The study was conducted over a wide range of concrete cube strengths ranging from 30 to 110 MPa. The external diameter of the steel tube-to-plate thickness (D/t) ratio ranged from 15 to 80 covering compact steel tube sections. An accurate finite element model was developed to carry out the analysis. Accurate nonlinear material models for confined concrete and steel tubes were used. The column strengths and load¿axial shortening curves were evaluated. The results obtained from the finite element analysis were verified against experimental results. An extensive parametric study was conducted to investigate the effects of different concrete strengths and cross-section geometries on the strength and behaviour of concrete-filled compact steel tube circular stub columns. The column strengths predicted from the finite element analysis were compared with the design strengths calculated using the American, Australian and European specifications. Based on the results of the parametric study, it is found that the design strengths given by the American Specifications and Australian Standards are conservative, while those of the European Code are generally unconservative. Reliability analysis was performed to evaluate the current composite column design rules.
    • ¿Behaviour of semi-rigid composite beam ¿ column connections with steel beams and precast hollow core slabs.

      Lam, Dennis; Fu, F. (2006)
      This paper is concerned with the behaviour of beam ¿ column connections of steel ¿ concrete composite beams with precast hollow core slabs. Experiments were carried out to investigate the joint rotation characteristics and ultimate moment capacity of these connections. Details of the test specimens, instrumentation, test set-up and test procedures are described. Results obtained for the connection moment capacity, rotation capacity and failure modes are presented. It is found that through proper design and detailing, these simple steel connections display the characteristics of a semi-rigid connection with very little extra cost.
    • Behaviour of strip footing on fiber-reinforced model slopes

      Mirzababaei, M.; Inibong, E.; Mohamed, Mostafa H.A.; Miraftab, M. (2014)
      Laboratory scale model slopes reinforced with waste carpet fibers were made in a rigid tank with dimensions of 800 mm x 300 mm x 500 mm. Bearing capacities of the strip footing rested on non-reinforced and fiber-reinforced model slopes with 1%, 3% and 5% fiber content were compared at 20% footing displacement ratio. The influence of location of footing on the bearing capacity was studied with placing the footing at different edge distances from the crest of the footing (i.e., 150 mm, 100 mm and 0). Suction probe sensors were installed at appropriate locations on the rear side of the model slope to measure the pore-water pressure generated due to the footing pressure. Results showed that fiber reinforcement increased the bearing resistance of the model slopes significantly. Inclusion of 5% fiber increased the bearing resistance by 271% compared to that of non-reinforced model slope at the footing edge distance ratio of 3. The location of footing was found to affect the load-carrying capacity of the fiber-reinforced model slope. The increase in the edge distance ratio of the footing increased the load-carrying capacity of the model slope.
    • Behaviours of circular CFDST with stainless steel external tube: Slender columns and beams

      Zhao, H.; Wang, R.; Lam, Dennis; Hou, C-C; Zhang, R. (Elsevier, 2021-01)
      In this work, experimental and numerical investigations were performed on the behaviours of circular concrete filled double steel tubular (CFDST) slender columns and beams, in which the external tube employed stainless steel tube. Eighteen specimens, 12 slender columns and 6 beams, were tested to obtain the failure patterns, load versus deflection relationships and strain developments of stainless steel tube. A finite element (FE) model was developed and verified by experimental results. The validated FE model was then employed to investigate the effects of key parameters, including hollow ratio, eccentric ratio and material strength, on the load-carrying capacity. The load distribution among the components and contact stress between steel tube and sandwiched concrete were also analyzed. Finally, the design methods for CFDST, hollow CFST and solid CFST members with carbon steel external tube respectively suggested by Han et al. (2018), Chinese GB 50936-2014 (2014) and AISC 360-16 (2016) were employed to evaluate their applicability for the circular CFDST slender columns and beams with stainless steel outer tube.
    • Bending of circular-section bonded rubber blocks.

      Horton, J.M.; Tupholme, Geoffrey E.; Gover, Michael J.C. (2002)
      Convenient exact closed-form expressions are derived for calculating the bending stiffness of and stresses within loaded cylindrical bonded rubber blocks of circular cross-section. The particular solutions for simple bending, cantilever loading and apparent shear situations are deduced and studied in detail. The shapes of the deformed profiles are discussed and confirmation is provided that the previously adopted assumption of parabolic profiles of the deformed lateral curved surface is only valid for blocks of very small aspect ratio. In simple bending a relationship which is more realistic than those hitherto suggested is derived for the couple required to maintain a specified rotation of the loaded end of the block. In apparent shear an exact expression for the ratio of the true to the apparent shear modulus is derived, and compared with the experimental data. An improved approximate relation is deduced.
    • BER performance of 2x2 and 4x4 transmit diversity MIMO in downlink LTE

      Uyoata, U.E.; Noras, James M. (2014-12)
      Multi-antenna(MIMO) techniques are reported to improve the performance of radio communication systems in terms of their capacity and spectral efficiency. In combination with appropriate receiver technologies they can also provide savings in the required transmit power with respect to target bit error rate. Long Term Evolution(LTE), one of the candidates for fourth generation(4G) mobile communication systems has MIMO as one of its underlying technologies and ITU defined channel models for its propagating environment. This paper undertakes a comprehensive verification of the performance of transmit diversity MIMO in the downlink sector of LTE. It uses models built using MATLAB to carry out simulations. It is deduced that generally increasing transmit diversity configuration from 2x2 to 4x4 offers SNR savings in flat fading channels though with a user equipment moving at 30km/hr, deploying 2x2 offers higher SNR saving below 7dB. Furthermore bandwidth variation has minimal effect on the BER performance of transmit MIMO except at SNR values above 9dB while the gains of higher modulation schemes come with a transmit power penalty.
    • Bi-fractional Wigner functions

      Agyo, Sanfo D.; Lei, Ci; Vourdas, Apostolos (2016)
      Two fractional Fourier transforms are used to define bi-fractional displacement operators, which interpolate between displacement operators and parity operators. They are used to define bi-fractional coherent states. They are also used to define the bi-fractional Wigner function, which is a two-parameter family of functions that interpolates between the Wigner function and the Weyl function. Links to the extended phase space formalism are also discussed.
    • Bi-fuel SI Engine Model for Analysis and Optimization

      Rezapour, Kambiz; Mason, Byron A.; Wood, Alastair S.; Ebrahimi, Kambiz M. (2014)
      The natural gas as an alternative fuel has economical and environmental benefits. Bi-fuel engines powered by gasoline and compressed natural gas (CNG) are an intermediate and alternative step to dedicated CNG engines. The conversion to bi-fuel CNG engine could be a short-term solution to air pollution problem in many developing countries. In this paper a mathematical model of a bi-fuel four-stroke spark ignition (SI) engine is presented for comparative studies and analysis. It is based on the two-zone combustion model, and it has the ability to simulate turbulent combustion. The model is capable of predicting the cylinder temperature and pressure, heat transfer, brake work , brake thermal and volumetric efficiency, brake torque, brake specific fuel consumption (BSFC), brake mean effective pressure (BMEP), concentration of CO2, brake specific CO (BSCO) and brake specific NOx (BSNOx). The effect of engine speed, equivalence ratio and performance parameters using gasoline and CNG fuels are analysed. The model has been validated by experimental data using the results obtained from a bi-fuel engine. The results show the capability of the model in terms of engine performance optimization and minimization of the emissions. The engine used in this study is a typical example of a modified bi-fuel engine conversion, which could benefit the researchers in the field.
    • Biaxially oriented polypropylene pipes: implications for impact and hydrostatic pressure resistance.

      Morath, C.C,; Ward, Ian M.; Soliman, M.; Voets, P.; Kleppinger, R. (2006)
      The Leeds die drawing process has been used to produce biaxially oriented polypropylene pipes with significant enhancement of hoop mechanical properties in terms of tensile modulus and tensile strength owing to a unique orientation of the ¿ crystallites throughout their cross-section. Pendulum impact tests on these pipes show major improvements in impact resistance. Hydrostatic pressure tests were undertaken at room temperature 95 and 110°C. Major improvements in behaviour were found including more than an order of magnitude increase in lifetime at 95°C. Furthermore, the toughness was improved enormously leading to a brittle tough transition temperature below ¿70°C.
    • BiCGStab, VPAStab and an adaptation to mildly nonlinear systems.

      Graves-Morris, Peter R. (2007)
      The key equations of BiCGStab are summarised to show its connections with Pade and vector-Pade approximation. These considerations lead naturally to stabilised vector-Pade approximation of a vector-valued function (VPAStab), and an algorithm for the acceleration of convergence of a linearly generated sequence of vectors. A generalisation of this algorithm for the acceleration of convergence of a nonlinearly generated system is proposed here, and comparative numerical results are given.
    • Big data in predictive toxicology

      Neagu, Daniel; Richarz, A-N. (Royal Society of Chemistry, 2019-12)
      The rate at which toxicological data is generated is continually becoming more rapid and the volume of data generated is growing dramatically. This is due in part to advances in software solutions and cheminformatics approaches which increase the availability of open data from chemical, biological and toxicological and high throughput screening resources. However, the amplified pace and capacity of data generation achieved by these novel techniques presents challenges for organising and analysing data output. Big Data in Predictive Toxicology discusses these challenges as well as the opportunities of new techniques encountered in data science. It addresses the nature of toxicological big data, their storage, analysis and interpretation. It also details how these data can be applied in toxicity prediction, modelling and risk assessment.
    • Bio-DME production based on conventional and CO2-enhanced gasification of biomass: A comparative study on exergy and environmental impacts

      Parvez, A.M.; Wu, T.; Li, S.; Miles, N.; Mujtaba, Iqbal M. (2018-03)
      In this study, a novel single-step synthesis of dimethyl ether (DME) based on CO2-enhanced biomass gasification was proposed and simulated using ASPEN PlusTM modelling. The exergetic and environmental evaluation was performed in comparison with a conventional system. It was found that the fuel energy efficiency, plant energy efficiency and plant exergetic efficiency of the CO2-enhanced system were better than those of the conventional system. The novel process produced 0.59 kg of DME per kg of gumwood with an overall plant energy efficiency of 65%, which were 28% and 5% higher than those of conventional systems, respectively. The overall exergetic efficiency of the CO2-enhanced system was also 7% higher. Exergetic analysis of each individual process unit in both the CO2-enhanced system and conventional systems showed that the largest loss occurred at gasification unit. However, the use of CO2 as gasifying agent resulted in a reduced loss at gasifier by 15%, indicating another advantage of the proposed system. In addition, the LCA analysis showed that the use of CO2 as gasifying agent could also result in less 21 environmental impacts compared with conventional systems, which subsequently made the CO2-22 enhanced system a promising option for a more environmental friendly synthesis of bio-DME.
    • Biomass-derived nanocellulose modified cementitious composites: A review

      Wang, D.; Dong, S.; Ashour, Ashraf F.; Wang, X.; Qiu, L.; Han, B. (elsevier, 2022)
      Cementitious composites, the most abundant human-made materials in the world, are challenged to be more sustainable, durable and cost-effective to adapt to the development of structural engineering, economy and environment. Owing to their excellent strength, toughness and durability, nano-fillers reinforced cementitious materials have attracted broad attention in civil engineering researches and applications. However, it is worth noting that nano-fillers reinforced cementitious materials achieve their proprieties by using of different industrial nano-fillers, i.e., graphenes, carbon nanotubes, carbon nanofibers, etc. Although the properties of conventional cementitious materials are improved, the incorporation of the above nano-fillers are high cost and environmental footprint. Different from high-energy consuming carbon nanofillers, nanocellulose is one of the biomass-derived nanofillers with excellent nanometer properties, biological performances and composite effects, and it has proved to be a promising green filler to enhance the mechanical properties, durability and functional properties and lower the carbon footprint of cementitious composites. Therefore, this paper provides an overview on biomass-derived nanocellulose modified cementitious composites, mainly focusing on their fabrication, properties (early performance, mechanical performance, durability, and functional performance) and applications. It also concludes with an outline of some future opportunities and challenges in the development of biomass-derived nanocellulose modified cementitious composites.
    • Biomaterials for breast reconstruction: Promises, advances, and challenges

      Abdul-Al, Mohamed; Zaernia, Amir; Sefat, Farshid (2020-11)
      Breast reconstruction is the opportunity that provides the chance of having breast after undergoing surgical removal of the breast tissue due to cancer-related surgery. However, this varies on the stage of the cancer diagnosis and the procedure undertaken. There are many regenerative medicine methods that provide several initiatives and direct solutions to problems such as the development of “bioactive tissue,” which can regenerate adipose tissues with similar normal functions and structures. There have been several studies which have previously explored for the improvement of breast reconstruction including different variations of biomaterials, different fabrication and processing techniques, cells as well as growth factors which enable bioengineers and tissue engineers to reconstruct a suitable breast for patients with breast cancer. Many factors such as shape, proper volume, mechanical properties have been studies but very scattered with not adequate solutions for existing patients worldwide. This review article aims to cover recent advances in biomaterials, which can be used for reconstruction of breasts as well as looking at the various factors that might lead to individuals needing reconstruction and the materials that are available. The focus would be to look at the various biomaterials that are available to use for reconstruction, their properties, and their structural integrity.
    • Biomechanics of ramp descent in unilateral trans-tibial amputees: Comparison of a microprocessor controlled foot with conventional ankle–foot mechanisms

      Struchkov, Vasily; Buckley, John G. (2016-02)
      Background Walking down slopes and/or over uneven terrain is problematic for unilateral trans-tibial amputees. Accordingly, ‘ankle’ devices have been added to some dynamic-response feet. This study determined whether use of a microprocessor controlled passive-articulating hydraulic ankle–foot device improved the gait biomechanics of ramp descent in comparison to conventional ankle–foot mechanisms. Methods Nine active unilateral trans-tibial amputees repeatedly walked down a 5° ramp, using a hydraulic ankle–foot with microprocessor active or inactive or using a comparable foot with rubber ball-joint (elastic) ‘ankle’ device. When inactive the hydraulic unit's resistances were those deemed to be optimum for level-ground walking, and when active, the plantar- and dorsi-flexion resistances switched to a ramp-descent mode. Residual limb kinematics, joints moments/powers and prosthetic foot power absorption/return were compared across ankle types using ANOVA. Findings Foot-flat was attained fastest with the elastic foot and second fastest with the active hydraulic foot (P < 0.001). Prosthetic shank single-support mean rotation velocity (p = 0.006), and the flexion (P < 0.001) and negative work done at the residual knee (P = 0.08) were reduced, and negative work done by the ankle–foot increased (P < 0.001) when using the active hydraulic compared to the other two ankle types. Interpretation The greater negative ‘ankle’ work done when using the active hydraulic compared to other two ankle types, explains why there was a corresponding reduction in flexion and negative work at the residual knee. These findings suggest that use of a microprocessor controlled hydraulic foot will reduce the biomechanical compensations used to walk down slopes.
    • Biometric of Intent: A New Approach Identifying Potential Threat in Highly Secured Facilities

      Al Hamar, J.; Chamieh, J.; Al-Mohannadi, Hamad; Al Hamar, M.; Al-Mutlaq, A.; Musa, Ahmad S. (2018)
      Biometric of Intent (BoI) is a Computer Vision (CV) automation, using Artificial Intelligence (AI) techniques, which presents a new approach that extends the reach of the classic biometric identification process. It provides an efficient mechanism which deters the threats raised by unknown individuals who have deceitful intentions and who aim to deploy unlawful operations such as terrorist attacks. In this context, our proposed BoI model is based on a framework constructed upon an automated machine learning facial expression analysis system which can assist law enforcement agencies who intend to deploy a systematic preventive security approach that aims to reduce the risk of potential unlawful attacks by rogue individuals through the evaluation of their emotional state in relation to their malicious intent.
    • Biometrics in the World of Electronic Borders

      Kumi Kyeremeh, George; Abdul-Al, Mohamed; Abduljabbar, Nabeel; Qahwaji, Rami S.R.; Abd-Alhameed, Raed A. (2021-12-06)
      Recently, the demand for border crossing has increased massively, with the aim to increase the processing and clearance speed at border crossing points (BCP). The attempt to improve travel convenience, Border Cross Point (BCP) output, and national security result in automated border control (ABC) with biometric technology having a major effect on the efficiency, and safety of the control processes. The border processing of BCP can be increased by automating biometric recognition and facilitated by clearance procedures. This paper discussed the two structures of an e-gate (ABC) and a prospective benefit of biometrics to the EU border in terms of accuracy, integrity, robustness, and efficiency. Challenges posed by biometrics in border control systems were identified and recommendations such as multimodal systems and smart systems with AI and machine learning were suggested to assist travelers to cross border points faster.