ORCID Profile
0000-0002-9905-9162
Current Organisation
University of Nottingham - Malaysia Campus
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Publisher: Springer Science and Business Media LLC
Date: 03-2017
DOI: 10.1557/MRC.2017.10
Abstract: Considered as a less hazardous piezoelectric material, potassium sodium niobate (KNN) has been in the fore of the search for replacement of lead (Pb) zirconate titanate for piezoelectrics applications. Here, we challenge the environmental credentials of KNN due to the presence of ~60 wt% Nb 2 O 5 , a substance much less toxic to humans than Pb oxide, but whose mining and extraction cause significant environmental damage.
Publisher: Trans Tech Publications, Ltd.
Date: 10-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.629.89
Abstract: The use of advanced materials in automotive, aerospace and communication technologies has called for re-assessment of classical models of many structural elements. The primary objective of this study relates to the use of a higher-order continuum model for discerning the contribution of certain geometric and material properties on wave propagation behavior of a spinning appendage of an aircraft appendage. The spinning appendage is characterized by a through-thickness functional material gradation and subjected to an axial dead load. The foundation of the present model rests on the trio of the mechanics of functionally graded solid structures, the extended Hamilton’s principle and the thin beam theory. Numerical results from the wave mechanics analyses reveal the noticeable influence of axial dead load and attendant wave splitting effect caused by the gyroscopic moment of the system. The wave mechanics result paves the way for the non-destructive damage testing of the element.
Publisher: Elsevier BV
Date: 2021
Publisher: BMJ
Date: 13-01-2021
DOI: 10.1136/BMJ.M4573
Abstract: To evaluate sodium-glucose cotransporter-2 (SGLT-2) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists in patients with type 2 diabetes at varying cardiovascular and renal risk. Network meta-analysis. Medline, Embase, and Cochrane CENTRAL up to 11 August 2020. Randomised controlled trials comparing SGLT-2 inhibitors or GLP-1 receptor agonists with placebo, standard care, or other glucose lowering treatment in adults with type 2 diabetes with follow up of 24 weeks or longer. Studies were screened independently by two reviewers for eligibility, extracted data, and assessed risk of bias. Frequentist random effects network meta-analysis was carried out and GRADE (grading of recommendations assessment, development, and evaluation) used to assess evidence certainty. Results included estimated absolute effects of treatment per 1000 patients treated for five years for patients at very low risk (no cardiovascular risk factors), low risk (three or more cardiovascular risk factors), moderate risk (cardiovascular disease), high risk (chronic kidney disease), and very high risk (cardiovascular disease and kidney disease). A guideline panel provided oversight of the systematic review. 764 trials including 421 346 patients proved eligible. All results refer to the addition of SGLT-2 inhibitors and GLP-1 receptor agonists to existing diabetes treatment. Both classes of drugs lowered all cause mortality, cardiovascular mortality, non-fatal myocardial infarction, and kidney failure (high certainty evidence). Notable differences were found between the two agents: SGLT-2 inhibitors reduced admission to hospital for heart failure more than GLP-1 receptor agonists, and GLP-1 receptor agonists reduced non-fatal stroke more than SGLT-2 inhibitors (which appeared to have no effect). SGLT-2 inhibitors caused genital infection (high certainty), whereas GLP-1 receptor agonists might cause severe gastrointestinal events (low certainty). Low certainty evidence suggested that SGLT-2 inhibitors and GLP-1 receptor agonists might lower body weight. Little or no evidence was found for the effect of SGLT-2 inhibitors or GLP-1 receptor agonists on limb utation, blindness, eye disease, neuropathic pain, or health related quality of life. The absolute benefits of these drugs vary substantially across patients from low to very high risk of cardiovascular and renal outcomes (eg, SGLT-2 inhibitors resulted in 3 to 40 fewer deaths in 1000 patients over five years see interactive decision support tool ( atch-it/200820dist/#!/ ) for all outcomes. In patients with type 2 diabetes, SGLT-2 inhibitors and GLP-1 receptor agonists reduced cardiovascular and renal outcomes, with some differences in benefits and harms. Absolute benefits are determined by in idual risk profiles of patients, with clear implications for clinical practice, as reflected in the BMJ Rapid Recommendations directly informed by this systematic review. PROSPERO CRD42019153180.
Publisher: Science Publishing Corporation
Date: 09-10-2018
DOI: 10.14419/IJET.V7I4.13.21347
Abstract: One-dimensional semi-infinite heat transfer solution is a common solution for transient heat transfer experiments. This solution is valid for a short certain amount of time before the semi-infinite solid became invalid. Crank Nicolson solution has been chosen to address this issue. This paper reports the time limitation for semi-infinite solid solution and justify the usability of Crank Nicolson solution given the same boundary conditions. The flat plate heat transfer experiment has been conducted. With the same boundary conditions, at Fourier number 0.1, the resultant heat transfer coefficient and adiabatic wall temperature have shown a good agreement between the semi-infinite solid solution and the Crank Nicolson solution. Beyond this Fourier number, both solutions have given inaccurate results. The inaccurate results are due to unsuitable boundary conditions. Future work will involve modification of the back face boundary conditions to address the time limitation of the one-dimensional semi-infinite solid heat transfer solution.
Publisher: Trans Tech Publications, Ltd.
Date: 2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/JNANOR.38.26
Abstract: The main aim of this work is to analyze the various heat transport mechanisms and their roles in efficiency enhancement of a thin-film solar cell due to embedded metallic nanoparticles at the rear of the cell, from both electrical and thermal aspects. The nanoparticles present deep inside the cell reflect incident radiation which then increases the optical path length for enhanced electricity generation. The increase in the optical path length also tends to induce additional but undesirable thermal heating which reduces the performance of the cells. The relationship between the improved conversion efficiency and the thermal effect is the crucial factor of maximizing the performance of thin-film solar cells and has yet to be explored. An accurate theoretical/numerical modeling is warranted in this case. Here, we present an analysis of combined light propagation and preliminary phonon transport in the cell to study solar-energy deposition and the associated thermal gradient.
Publisher: Elsevier
Date: 2022
Publisher: River Publishers
Date: 25-07-2017
Publisher: Elsevier BV
Date: 02-2023
Publisher: IEEE
Date: 05-2015
Publisher: Elsevier
Date: 2020
Publisher: Elsevier BV
Date: 10-2020
Publisher: AIP Publishing
Date: 11-2022
DOI: 10.1063/5.0124416
Abstract: One of the many ways of cavitation utilized for process intensification is through acoustically inducing it. As acoustic cavitation gained traction in recent industrial works, numerical modeling became an important study tool to scrutinize and optimize acoustic cavitation applications. However, available hydrodynamic cavitation models are found incapable of accurately predicting acoustic cavitation structures and flow features. This could source from the oversimplification of the Rayleigh–Plesset equation or from obscure effects of empirical model constants. To address this issue, new mass transfer source terms for Zwart–Gerber–Belamri model were derived based on the consideration of Rayleigh–Plesset's second-order derivatives. In addition, a design of experiments statistical approach, coupled with Monte Carlo simulations, was implemented to assess the influence of empirical model constants on the model's performance by examining variations in litude and frequency responses. Moreover, a set of optimized model constants was obtained: evaporation constant = 17.359 88, condensation constant = 0.1, Bubble Radius = 25 × 10−6 m, and Nucleation Site Volume Fraction = 5 × 10−4, to obtain a maximum pressure and frequency of 3.62 bar and 4128.73 Hz, respectively. The new model, with the new constants, was configured into ANSYS Fluent 22.1 and validated against experimental values. The new model resulted with maximum pressure and frequency of 3.48 bar and 4894.56 Hz, respectively, validating the statistical model and showing drastic improvement in qualitatively and quantitatively capturing acoustic cavitation.
Publisher: MDPI AG
Date: 16-08-2022
DOI: 10.3390/SU141610141
Abstract: Four-dimensional (4D) printing of shape memory polymers is a leading research field due to the possibilities allowed by using these materials. The strain difference in the structures that is caused by the different stiffness profiles can be used to influence the shape-memory effect in the actuators. In this study, the influence of patterns on the strain is tested in polylactic acid (PLA) actuators using patterns made of different shapes. Five bioinspired geometrical shapes, namely, circles, squares, hexagons, rhombuses, and triangles, are used in the three-dimensional (3D) printing of the actuators. The use of shapes of different sizes along with combinations of different patterns in the PLA actuators is carried out to develop 40 actuators with different designs. The effects of the patterns and their characteristics are analysed and compared. The self-bending angles of the actuators range from 6.19° to 30.86°, depending on the patterns and arrangement used. To demonstrate the feasibility of utilizing the proposed designs in practical applications, a hand-like shaped gripper is developed. The results show that the gripper can grip objects with uniform and non-uniform cross-sections. The developed gripper demonstrates that the proposed concept can be implemented in various applications, including self-morphing structures and soft robotics.
Publisher: Elsevier BV
Date: 04-2012
Publisher: Elsevier BV
Date: 12-2017
Publisher: Elsevier BV
Date: 11-2010
Publisher: Springer Singapore
Date: 2019
Publisher: Elsevier BV
Date: 12-2010
Publisher: Elsevier BV
Date: 12-2023
Publisher: Elsevier BV
Date: 09-2021
Publisher: Elsevier BV
Date: 05-2015
Publisher: Elsevier BV
Date: 10-2020
Publisher: River Publishers
Date: 04-03-2015
Publisher: Elsevier BV
Date: 2013
Publisher: Elsevier BV
Date: 07-2012
Publisher: Elsevier BV
Date: 10-2020
Publisher: Elsevier BV
Date: 10-2020
Publisher: Elsevier BV
Date: 03-2019
Publisher: World Scientific Pub Co Pte Ltd
Date: 23-10-2017
DOI: 10.1142/S0219455417501103
Abstract: Some high-speed rotating micro-machines and micro-vibration devices rely on the use of whirling micro-shafts subject to the effect of gravity and magnetic fields. At present, the consequences of the interaction between the elastic deformation of such shafts and the magnetic/gravitational field effects remain unresolved. Focusing on micro-scale whirling shafts with very high torsional rigidity, this study presents a theoretical treatment grounded in the theory of micro-continuum elasticity to examine the ramification of this interaction. The differential transformation method (DTM) is used to obtain extensive numerical results for qualitative assessments of the magnetic-gravitational effects interaction on standing, hanging and horizontally positioned spinning micro-scale shafts. The influence of bearing-support flexibility on the response of the whirling micro-shaft is also considered with rotational and translational springs. The gravitational sag reduces the stability of whirling standing micro-shafts and increases that of the hanging micro-shafts. Further, for all the micro-shafts configurations investigated, the magnetic field is observed to stiffen the response of the shaft and favorably shifts the critical points of vibration of the whirling shafts forward.
Publisher: Elsevier BV
Date: 08-2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2023
Publisher: Elsevier BV
Date: 11-2014
Publisher: SAGE Publications
Date: 14-01-2020
Abstract: A model is proposed for investigating the size-dependent frequency response of arbitrarily oriented microscale frames used in the build-up of lattice structures with micro unit cells. The model employs the Rayleigh–Love, the Timoshenko and the modified couple stress theories to overcome the weaknesses of the conventional theories. Descriptions of the model and finite element implementation are presented. Predictions from the reduced forms of the model agree with published results. The frequency analyses of different microscale frames reveal the influence of material lengthscale, dead weight, lateral inertia and orientation angles. For small aspect ratios, neglecting the lateral inertia effect incurs a substantial error in predicting the frequencies of higher modes, but only marginally affects the lower modes. The resonant frequencies exhibit a sharp drop in the presence of dead weight, but it increases in the presence of material lengthscale.
Publisher: Science Publishing Corporation
Date: 15-09-2018
DOI: 10.14419/IJET.V7I4.3.19547
Abstract: The purpose of this work was to develop a criterion for estimating the quality factor of the tribosystem and to assess its effect on wear rate, friction coefficient and run-in time. The basis of the methodological approach when developing a criterion for the quality of the tribosystem is the parameters that take into account the construction of the tribosystem, the thermal diffusivity of materials and the loading conditions of the tribosystems.The definition of the quality of the tribosystem has been further developed, which, unlike the known one, takes into account the geometric dimensions and kinematic scheme of the tribosystem, the thermal diffusivity of materials and the rate of propagation of deformation in the surface layers of the triboelement materials during their contact interaction. Theoretical and experimental studies established the relationship between the quality value, wear rate and the friction coefficient in the process of running-in. It is shown that the increase in quality helps to reduce the above-mentioned parameters.The relationship between the running-in time and the quality value is established. It is shown that the process of running-in can be controlled. To reduce the running-in time, it is necessary to reduce the sliding speed during the transient process and to increase the tribological properties of the lubricating medium. The presented theoretical and experimental studies allow us to state that the quality of tribosystems Q can be a measure of the potential ability of the tribosystem to adapt (adapt) to operating conditions, providing the maximum resource.
Publisher: Elsevier BV
Date: 06-2021
Publisher: Wiley
Date: 10-09-2015
Publisher: SAGE Publications
Date: 09-09-2015
Abstract: We used the data of 297 participants (15-64 years old) from a cohort study (2003-2010) who were free from hypertension at baseline, to develop a risk score to predict hypertension by primary health care workers in rural India. Age ≥35 years, current smoking, prehypertension, and central obesity were significantly associated with incident hypertension. The optimal cutoff value of ≥3 had a sensitivity of 78.6%, specificity of 65.2%, positive predictive value of 41.1%, and negative predictive value of 90.8%. The area under the receiver operating characteristic curve of the risk score was 0.802 (95% confidence interval = 0.748-0.856). This simple and easy to administer risk score could be used to predict hypertension in primary care settings in rural India.
Publisher: AIP Publishing LLCMelville, New York
Date: 22-05-2021
DOI: 10.1063/9780735423152_004
Abstract: Solar photovoltaic (PV) technology has undergone a tremendous evolution in terms of mainstream adoption, capital cost, capacity, and industrial-scale production in recent years. However, this evolution has also sparked scrutiny of the environmental profiles of the PV ecosystem. Along this direction, this chapter centers on life cycle analysis (LCA), which has emerged as an invaluable tool for the assessment of the energy requirements and environmental profile from cradle to grave of PV systems. It explores PV's pivotal position among sustainable energy transformation schemes examines material supply criticality on PV's development and highlights the quantitative trends of conversion efficiency, energy payback time, and CO2 emissions of different modules. A snapshot of a framework within a case study for conducting the LCA of a laboratory-scale PV module with new material architecture is provided. This serves the requirements to establish and develop new guidelines and methods that integrate environmental factors into the PV technology development process at the design and fabrication stages before upscaling and transitioning from laboratory to market. A succinct discussion on the associated issues of scaling up laboratory processes to industrial scale alongside the challenges of end-of-life evaluations of PV modules is also provided.
Publisher: Springer Science and Business Media LLC
Date: 09-10-2021
Publisher: SAGE Publications
Date: 05-03-2012
Abstract: This study presents a distributed parameter model for the transverse vibration analysis of a micro end mill. Owing to its geometrical nonuniformity, the micro end mill is spatially sub-structured into three distinct spinning elastic systems. With the application of the extended Hamilton’s principle to the energy expressions of the spinning elastic systems, the governing equations of each sub-structured system are obtained. The overall analytical model incorporates a number of nonclassical structural effects that range from rotary inertia, shear deformation, taper ratio, to the rate of twist. For detailed frequency analyses, systematic solution of the elastodynamics governing equations is provided with the spectral finite element method. To assess the accuracy of the presented method, the frequency values of each of the spatial sub-structure are validated through available results in the literature. In the same vein, the solution of the entire ensemble of the distributed parameter system compares well with ANSYS® simulation. The investigation reveals the spinning rate to have the most significant effect on the frequency value of the micro tool followed by the taper ratio and the complex geometry of the micro flute.
Publisher: Elsevier BV
Date: 12-2019
Publisher: Elsevier BV
Date: 2012
Publisher: Elsevier BV
Date: 10-2020
Publisher: CRC Press
Date: 17-04-2018
DOI: 10.1201/B22398
Publisher: Wiley
Date: 05-10-2021
DOI: 10.1002/CNM.3531
Abstract: Research evidence abounds on the effectiveness of micropillar‐based microelectromechanical systems for the detection of a wide variety of ultrasmall biological objects for clinical and non‐clinical applications. However, the standard micropillar‐based sensing platforms rely on a single‐column micropillar with a spot at the tip for binding of objects. Although this long‐standing form has shown immense potential, performance improvement is hindered by the fundamental limits enforced by physical laws. Moreover, the single‐column micropillar has a lower sensing area and is ill‐suited for a simultaneous differential sensing of chemical/biological objects of different mass. Here, we report a new set of nature‐inspired, branched micropillar‐based sensing resonators to address the highlighted issues. The characteristics of the newly proposed branched micropillars are comprehensively examined with three payloads ( Bartonella Bacilliformis , Escherichia coli , and Micro magnetic beads ). Anchored on the capability of continuum theoretical framework, the mathematical model of the micropillar is formulated through the synthesis of the modified couple stress, the Rayleigh‐Love, and the Timoshenko theories. The finite element method is employed to shed light on the variability of the structures' resonant response under performance reduction factors (payload's rotary inertia, damaged substrate, and density of a surrounding fluid). The results obtained indicate superior performance indicators for the triply‐branched micropillar: enhanced response sensitivity for multiple payloads and less susceptibility to deterioration in resonant frequencies due to fluid immersion.
Publisher: Elsevier
Date: 2022
Publisher: World Scientific Pub Co Pte Lt
Date: 06-2016
DOI: 10.1142/S0219455415500224
Abstract: Approximate numerical solutions are obtained for the vibration response of a functionally graded (FG) micro-scale beam entrapped within an axially-directed magnetic field using the differential transformation method (DTM). Idealized as a one-dimensional (1D) continuum with a noticeable microstructural effect and a thickness-directed material gradient, the microbeam’s behavior is studied under a range of nonclassical boundary conditions. The immanent microstructural effect of the micro-scale beam is accounted for through the modified couple stress theory (MCST), while the microscopic inhomogeneity is smoothened with the classical rule of mixture. The study demonstrates the robustness and flexibility of the DTM in providing benchmark results pertaining to the free vibration behavior of the FG microbeams under the following boundary conditions: (a) Cl ed-tip mass (b) cl ed-elastic support (transverse spring) (c) pinned-elastic support (transverse spring) (d) cl ed-tip mass-elastic support (transverse spring) (e) cl ed-elastically supported (rotational and transverse springs) and (f) fully elastically restrained (transverse and rotational springs on both boundaries). The analyses revealed the possibility of using functional gradation to adjust the shrinking of the resonant frequency to zero (rigid-body motion) as the mass ratio tends to infinity. The magnetic field is noted to have a negligibly minimal influence when the gradient index is lower, but a notably dominant effect when it is higher.
Publisher: Elsevier BV
Date: 2022
Location: Singapore
Location: Saudi Arabia
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Khameel Mustapha.