Vijay Ganji, Tahra ElObeid, Zumin Shi, Hiba Bawadi, Abdelhamid Kerkadi, Noor Moussa, Hoda Ali and Alshaimaa Sobeih
Prevalence of vitamin D insufficiency among young Qatari women is ∼85%. The purpose of the study was to develop a food frequency questionnaire (FFQ) and to assess the degree of…
Abstract
Purpose
Prevalence of vitamin D insufficiency among young Qatari women is ∼85%. The purpose of the study was to develop a food frequency questionnaire (FFQ) and to assess the degree of agreement between food vitamin D intakes derived from FFQ and 24-h food recall (24HFR) in young Qatari women.
Design/methodology/approach
A vitamin D-centric, 40-item FFQ was developed based on foods consumed in Qatar. In total, 36 Qatari women provided food intakes using FFQ and 24HFR. Vitamin D contents of foods reported in FFQ and 24HFR were computed. Spearman rank correlation was used to evaluate the relation between vitamin D intakes of FFQ and 24HFR. Bland–Altman (BA) plot and quartile comparisons were performed to determine the degree of agreement between food intakes of FFQ and 24HFR.
Findings
Median intakes of vitamin D from FFQ were significantly higher compared to the vitamin D content from 24HFR (213 IU vs 126 IU; p < 0.008). Vitamin D intakes were lower with 24HFR when compared with the intakes of FFQ. There was no significant relationship between food vitamin D intake from FFQ and 24HFR (Spearman rho = 0.16; p < 0.35). In cross classification, ∼64% were assigned to the same or adjacent quartiles. As per BA plot, more than 95% food intakes were within the limits of agreement (LOA) (BA index, 2.8%).
Originality/value
There was a moderate agreement between vitamin D intakes and FFQ and 24HFR. 24HFR should be used with caution in assessing the habitual food vitamin D intake because of limited sources of the vitamer in Qatari cuisine. The FFQ is suitable for estimating the food vitamin D intake in young Qatari women.
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V.P. Iu and Y.K. Cheung
The theoretical development of the incremental finite element for non‐linear vibration of multilayer sandwich plates was presented in Part 1 and the equation of motion was…
Abstract
The theoretical development of the incremental finite element for non‐linear vibration of multilayer sandwich plates was presented in Part 1 and the equation of motion was established. In the second part of the paper, the solution techniques are described and a number of examples are given.
V.P. Iu and Y.K. Cheung
The first part of this paper presents an incremental variational principle and an incremental finite element in time‐space domain for the analysis of large amplitude, periodic…
Abstract
The first part of this paper presents an incremental variational principle and an incremental finite element in time‐space domain for the analysis of large amplitude, periodic vibration of multilayer sandwich plates. A reduced basis composed of eigenvectors corresponding to linear free vibration is introduced to reduce the order of the resulting linearized equations governing the non‐linear motion which are solved incrementally in association with Newton‐Raphson iterative method and an extrapolating technique. In the second part the solution techniques are described in detail and a number of examples on various non‐linear responses of rectangular multilayer sandwich plates, including superharmonic, subharmonic and internal resonance, are included in the study. Viscous modal damping is also considered when the structure is under forced excitation.
Y.K. Cheung and V.P. Iu
A simple numerical algorithm is developed for the implementation of the harmonic balance method to analyse periodic responses of a general dynamic system having geometrical…
Abstract
A simple numerical algorithm is developed for the implementation of the harmonic balance method to analyse periodic responses of a general dynamic system having geometrical non‐linearities of the quadratic and cubic types. The resulting non‐linear algebraic equations which are not explicitly determined are solved by non‐linear equation routines available in most mathematical libraries. Various non‐linear responses, such as the combinational resonances of a hinged‐clamped beam, the non‐linear effect on degenerate vibration modes of a square plate and the non‐linear oscillation of thin rings, are presented to demonstrate the versatility of the algorithm.
This bibliography contains references to papers, conference proceedings, theses and books dealing with finite strip, finite prism and finite layer analysis of structures…
Abstract
This bibliography contains references to papers, conference proceedings, theses and books dealing with finite strip, finite prism and finite layer analysis of structures, materially and/or geometrically linear or non‐linear.
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Mahdi Shayanmehr and Omid Basiri
In this paper, the important aspects of vibration analysis of carbon nanotubes (CNTs) as nano-resonators are studied. This study has covered the important nonlinear phenomena such…
Abstract
Purpose
In this paper, the important aspects of vibration analysis of carbon nanotubes (CNTs) as nano-resonators are studied. This study has covered the important nonlinear phenomena such as jump super-harmonic and chaotic behavior. CNT is modeled by using the modified nonlocal theory (MNT).
Design/methodology/approach
In previous research studies, the effects of CNT’s rotary inertia, stiffness and shear modulus of the medium were neglected. So by considering these terms in MNT, a comprehensive model of vibrational behavior of carbon nanotube as a nanosensor is presented. The nanotube is modeled as a nonlocal nonlinear beam. The first eigenmode of an undamped simply supported beam is used to extract the nonlinear equation of CNT. Harmonic balance method is used to solve the equation, while to study its super-harmonic behavior, higher-order harmonic terms were used.
Findings
In light of frequency response equation, jump phenomenon and chaotic behavior of the nanotube with respect to the amplitude of excitation are investigated. Also in each section of the study, the effects of elastic medium and nonlocal parameters on the vibration behavior of nanotube are investigated. Furthermore, parts of the results in linear and nonlinear cases were compared with results of other references.
Originality/value
The present modification of the nonlocal theory is so important and useful for accurate investigation of the vibrational behavior of nano structures such as a nano-resonator.
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Dileep Bonthu, Bharath H.S., Siddappa I. Bekinal, P. Jeyaraj and Mrityunjay Doddamani
The purpose of this study was to introduce three-dimensional printing (3DP) of functionally graded sandwich foams (FGSFs). This work was continued by predicting the mechanical…
Abstract
Purpose
The purpose of this study was to introduce three-dimensional printing (3DP) of functionally graded sandwich foams (FGSFs). This work was continued by predicting the mechanical buckling and free vibration behavior of 3DP FGSFs using experimental and numerical analyses.
Design/methodology/approach
Initially, hollow glass microballoon-reinforced high-density polyethylene-based polymer composite foams were developed, and these materials were extruded into their respective filaments. These filaments are used as feedstock materials in fused filament fabrication based 3DP for the development of FGSFs. Scanning electron microscopy analysis was performed on the freeze-dried samples to observe filler sustainability. Furthermore, the density, critical buckling load (Pcr), natural frequency (fn) and damping factor of FGSFs were evaluated. The critical buckling load (Pcr) of the FGSFs was estimated using the double-tangent method and modified Budiansky criteria.
Findings
The density of FGSFs decreased with increasing filler percentage. The mechanical buckling load increased with the filler percentage. The natural frequency corresponding to the first mode of the FGSFs exhibited a decreasing trend with an increasing load in the pre-buckling regime and an increase in post-buckled zone, whereas the damping factor exhibited the opposite trend.
Originality/value
The current research work is valuable for the area of 3D printing by developing the functionally graded foam based sandwich beams. Furthermore, it intended to present the buckling behavior of 3D printed FGSFs, variation of frequency and damping factor corresponding to first three modes with increase in load.
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Smita Parida and Sukesh Chandra Mohanty
The purpose of this paper is to investigate the linear and non-linear free vibration of a functionally graded material (FGM) rotating cantilever plate in the thermal environment…
Abstract
Purpose
The purpose of this paper is to investigate the linear and non-linear free vibration of a functionally graded material (FGM) rotating cantilever plate in the thermal environment. The study employs the development of a non-linear mathematical model using the higher order shear deformation theory in which the traction free condition is applied to derive the simplified displacement model with seven field variables instead of nine.
Design/methodology/approach
A mathematical model is developed based on the higher order shear deformation theory using von-Karman type non-linearity. The rotating plate domain has been discretized into C0 eight-noded quadratic serendipity elements with node wise 7 degrees of freedom. The material properties are considered temperature dependent and graded along the thickness direction obeying a simple power law distribution in terms of the volume fraction of constituents, based on Voigt’s micromechanical method. The governing equations are derived using Hamilton’s principle and are solved using the direct iterative method.
Findings
The importance of the present mathematical model developed for numerical analysis has been stated through the comparison studies. The results provide an insight into the vibration response of FGM rotating plate under thermal environment. The influence of various parameters like setting angle, volume fraction index, hub radius, rotation speed parameter, aspect ratio, side-thickness ratio and temperature gradient on linear and non-linear frequency parameters is discussed in detail.
Originality/value
A non-linear mathematical model is newly developed based on C0 continuity for the functionally graded rotating plate considering the 1D Fourier equation of heat conduction. The present findings can be utilized for the design of rotating plates made up of a FGM in the thermal environment under real-life situations.
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The concept and practice of e-services has become essential in business transactions. Yet there are still many organizations that have not developed e-services optimally. This is…
Abstract
The concept and practice of e-services has become essential in business transactions. Yet there are still many organizations that have not developed e-services optimally. This is especially relevant in the context of Indonesian Airline companies. Therefore, many airline customers in Indonesia are still in doubt about it, or even do not use it. To fill this gap, this study attempts to develop a model for e-services adoption and empirically examines the factors influencing the airlines customers in Indonesia in using e-services offered by the Indonesian airline companies. Taking six Indonesian airline companies as a case example, the study investigated the antecedents of e-services usage of Indonesian airlines. This study further examined the impacts of motivation on customers in using e-services in the Indonesian context. Another important aim of this study was to investigate how ages, experiences and geographical areas moderate effects of e-services usage.
The study adopts a positivist research paradigm with a two-phase sequential mixed method design involving qualitative and quantitative approaches. An initial research model was first developed based on an extensive literature review, by combining acceptance and use of information technology theories, expectancy theory and the inter-organizational system motivation models. A qualitative field study via semi-structured interviews was then conducted to explore the present state among 15 respondents. The results of the interviews were analysed using content analysis yielding the final model of e-services usage. Eighteen antecedent factors hypotheses and three moderating factors hypotheses and 52-item questionnaire were developed. A focus group discussion of five respondents and a pilot study of 59 respondents resulted in final version of the questionnaire.
In the second phase, the main survey was conducted nationally to collect the research data among Indonesian airline customers who had already used Indonesian airline e-services. A total of 819 valid questionnaires were obtained. The data was then analysed using a partial least square (PLS) based structural equation modelling (SEM) technique to produce the contributions of links in the e-services model (22% of all the variances in e-services usage, 37.8% in intention to use, 46.6% in motivation, 39.2% in outcome expectancy, and 37.7% in effort expectancy). Meanwhile, path coefficients and t-values demonstrated various different influences of antecedent factors towards e-services usage. Additionally, a multi-group analysis based on PLS is employed with mixed results. In the final findings, 14 hypotheses were supported and 7 hypotheses were not supported.
The major findings of this study have confirmed that motivation has the strongest contribution in e-services usage. In addition, motivation affects e-services usage both directly and indirectly through intention-to-use. This study provides contributions to the existing knowledge of e-services models, and practical applications of IT usage. Most importantly, an understanding of antecedents of e-services adoption will provide guidelines for stakeholders in developing better e-services and strategies in order to promote and encourage more customers to use e-services. Finally, the accomplishment of this study can be expanded through possible adaptations in other industries and other geographical contexts.
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Cuicui Feng, Ming Yi, Min Hu and Fuchuan Mo
The environment in which users acquire medical and health information has changed dramatically, with online health communities (OHCs) emerging as an essential means for accessing…
Abstract
Purpose
The environment in which users acquire medical and health information has changed dramatically, with online health communities (OHCs) emerging as an essential means for accessing health information. It is imperative to comprehend the factors that shape the users' compliance willingness (UCW) to health information in OHCs.
Design/methodology/approach
This study adopted the information adoption model (IAM) and theory of planned behavior (TPB) to investigate the influence of argument quality (AQ), source credibility (SC) and subjective norms (SN) on UCW while considering the two types of online health information – mature and emerging treatments. The authors conducted an explanatory-predictive study based on a 2 (treatment types: mature vs. emerging) * 2 (AQ: high vs. low) * 2 (SC: high vs. low) scenario-based experiment, using the partial least squares structural equation modeling (PLS-SEM).
Findings
SC positively influences AQ. AQ, SC and SN contribute to information usefulness (IU). These factors positively affect UCW through the mediation of IU. SN were found to improve UCW directly. Moreover, the moderating effect of SC on AQ and IU was more substantial for emerging treatments.
Originality/value
The research model integrates IAM and TPB, considering information types as an additional variable. The approach and findings provide a valuable explanation for UCW to health information in OHCs.