Displaying publications 161 - 180 of 735 in total

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  1. Aziz F, Arof H, Mokhtar N, Shah NM, Khairuddin ASM, Hanafi E, et al.
    PLoS One, 2018;13(8):e0202092.
    PMID: 30157219 DOI: 10.1371/journal.pone.0202092
    In this paper, an image-based waste collection scheduling involving a node with three waste bins is considered. First, the system locates the three bins and determines the waste level of each bin using four Laws Masks and a set of Support Vector Machine (SVM) classifiers. Next, a Hidden Markov Model (HMM) is used to decide on the number of days remaining before waste is collected from the node. This decision is based on the HMM's previous state and current observations. The HMM waste collection scheduling seeks to maximize the number of days between collection visits while preventing waste contamination due to late collection. The proposed system was trained using 100 training images and then tested on 100 test images. Each test image contains three bins that might be shifted, rotated, occluded or toppled over. The upright bins could be empty, partially full or full of garbage of various shapes and sizes. The method achieves bin detection, waste level classification and collection day scheduling rates of 100%, 99.8% and 100% respectively.
    Matched MeSH terms: Models, Theoretical*
  2. Shehzad A, Bashir MJK, Horttanainen M, Manttari M, Havukainen J, Abbas G
    Environ Technol, 2018 Jul;39(14):1841-1850.
    PMID: 28595513 DOI: 10.1080/09593330.2017.1340350
    The present study explores the potential of MSW gasification for exergy analysis and has been recently given a premier attention in a region like Pakistan where the urbanization is rapidly growing and resources are few. The plant capacity was set at 50 MW based on reference data available and the total exergetic efficiency was recorded to be 31.5 MW. The largest irreversibility distribution appears in the gasifier followed by methanation unit and CO2 capture. The effect of process temperature, equivalence ratio and MSW moisture content was explored for inspecting the variations in syngas composition, lower heating value, carbon conversion efficiency and cold gas efficiency. Special attention of the paper is paid to the comparative assessment of MSW gasification products in four regions, namely Pakistan, USA, UAE and Thailand. This extended study gave an insight into the spectrum of socioeconomic conditions with varying MSW compositions in order to explain the effect of MSW composition variance on the gasification products.
    Matched MeSH terms: Models, Theoretical*
  3. Irfan SA, Razali R, KuShaari K, Mansor N, Azeem B, Ford Versypt AN
    J Control Release, 2018 02 10;271:45-54.
    PMID: 29274697 DOI: 10.1016/j.jconrel.2017.12.017
    Nutrients released into soils from uncoated fertilizer granules are lost continuously due to volatilization, leaching, denitrification, and surface run-off. These issues have caused economic loss due to low nutrient absorption efficiency and environmental pollution due to hazardous emissions and water eutrophication. Controlled-release fertilizers (CRFs) can change the release kinetics of the fertilizer nutrients through an abatement strategy to offset these issues by providing the fertilizer content in synchrony with the metabolic needs of the plants. Parametric analysis of release characteristics of CRFs is of paramount importance for the design and development of new CRFs. However, the experimental approaches are not only time consuming, but they are also cumbersome and expensive. Scientists have introduced mathematical modeling techniques to predict the release of nutrients from the CRFs to elucidate fundamental understanding of the dynamics of the release processes and to design new CRFs in a shorter time and with relatively lower cost. This paper reviews and critically analyzes the latest developments in the mathematical modeling and simulation techniques that have been reported for the characteristics and mechanisms of nutrient release from CRFs. The scope of this review includes the modeling and simulations techniques used for coated, controlled-release fertilizers.
    Matched MeSH terms: Models, Theoretical*
  4. Chen C, Chong NS, Smith R
    Math Biosci, 2018 02;296:98-112.
    PMID: 29273381 DOI: 10.1016/j.mbs.2017.12.002
    Mass-media reports on an epidemic or pandemic have the potential to modify human behaviour and affect social attitudes. Here we construct a Filippov model to evaluate the effects of media coverage and quarantine on the transmission dynamics of influenza. We first choose a piecewise smooth incidence rate to represent media reports being triggered once the number of infected individuals exceeds a certain critical level [Formula: see text] . Further, if the number of infected cases increases and exceeds another larger threshold value [Formula: see text] ( [Formula: see text] ), we consider that the incidence rate tends to a saturation level due to the protection measures taken by individuals; meanwhile, we begin to quarantine susceptible individuals when the number of susceptible individuals is larger than a threshold value Sc. Then, for each susceptible threshold value Sc, the global properties of the Filippov model with regard to the existence and stability of all possible equilibria and sliding-mode dynamics are examined, as we vary the infected threshold values [Formula: see text] and [Formula: see text] . We show generically that the Filippov system stabilizes at either the endemic equilibrium of the subsystem or the pseudoequilibrium on the switching surface or the endemic equilibrium [Formula: see text] depending on the choice of the threshold values. The findings suggest that proper combinations of infected and susceptible threshold values can maintain the number of infected individuals either below a certain threshold level or at a previously given level.
    Matched MeSH terms: Models, Theoretical*
  5. Atee HA, Ahmad R, Noor NM, Rahma AM, Aljeroudi Y
    PLoS One, 2017;12(2):e0170329.
    PMID: 28196080 DOI: 10.1371/journal.pone.0170329
    In image steganography, determining the optimum location for embedding the secret message precisely with minimum distortion of the host medium remains a challenging issue. Yet, an effective approach for the selection of the best embedding location with least deformation is far from being achieved. To attain this goal, we propose a novel approach for image steganography with high-performance, where extreme learning machine (ELM) algorithm is modified to create a supervised mathematical model. This ELM is first trained on a part of an image or any host medium before being tested in the regression mode. This allowed us to choose the optimal location for embedding the message with best values of the predicted evaluation metrics. Contrast, homogeneity, and other texture features are used for training on a new metric. Furthermore, the developed ELM is exploited for counter over-fitting while training. The performance of the proposed steganography approach is evaluated by computing the correlation, structural similarity (SSIM) index, fusion matrices, and mean square error (MSE). The modified ELM is found to outperform the existing approaches in terms of imperceptibility. Excellent features of the experimental results demonstrate that the proposed steganographic approach is greatly proficient for preserving the visual information of an image. An improvement in the imperceptibility as much as 28% is achieved compared to the existing state of the art methods.
    Matched MeSH terms: Models, Theoretical*
  6. Ahmed A, Al-Amin AQ, Rasiah R
    Environ Sci Pollut Res Int, 2019 Oct;26(29):30003-30015.
    PMID: 31414393 DOI: 10.1007/s11356-019-06141-7
    This study critically evaluates two COP proposals on Malaysia that have been under consideration to reduce climate damage. A top-down disaggregation framework deploying an "Empirical Regional Downscaling Dynamic Integrated Model of Climate and the Economy" is used to evaluate the local government climate roadmap and Malaysia's emissions reduction agendas under COP21 and subsequently COP22 proposals. The findings show that the costs from climate damage over the period 2010-2110 under the Malaysian Optimal Climate Action scenario will amount to MYR5,483 (US$1589) billion. The commensurate climate damage costs under the COP21 and COP22 scenario would be MYR5, 264 (US$1526) billion. Thus, the effective proposal for reducing climate damage in Malaysia over the period 2010-2110 is the COP22 time-adjusted COP21 proposal but there are a number of macroeconomic cost implications for savings and consumption that policy makers must address before acting.
    Matched MeSH terms: Models, Theoretical*
  7. Cheung ML, Chau KY, Lam MHS, Tse G, Ho KY, Flint SW, et al.
    Int J Environ Res Public Health, 2019 Jun 26;16(13).
    PMID: 31247962 DOI: 10.3390/ijerph16132257
    With the advancement of information technology, wearable healthcare technology has emerged as one of the promising technologies to improve the wellbeing of individuals. However, the adoption of wearable healthcare technology has lagged when compared to other well-established durable technology products, such as smartphones and tablets, because of the inadequate knowledge of the antecedents of adoption intention. The aim of this paper is to address an identified gap in the literature by empirically testing a theoretical model for examining the impact of consumers' health beliefs, health information accuracy, and the privacy protection of wearable healthcare technology on perceived usefulness. Importantly, this study also examines the influences of perceived usefulness, consumer innovativeness, and reference group influence on the adoption intention of wearable healthcare technology. The model seeks to enhance understanding of the influential factors in adopting wearable healthcare technology. Finally, suggestions for future research for the empirical investigation of the model are provided.
    Matched MeSH terms: Models, Theoretical*
  8. Farhan N, Rageh Al-Maleki A, Ataei S, Muhamad Sarih N, Yahya R
    Bioorg Chem, 2023 Jun;135:106511.
    PMID: 37027951 DOI: 10.1016/j.bioorg.2023.106511
    Medication products from natural materials are preferred due to their minimal side effects. Extra-virgin olive oil (EVOO) is a highly acclaimed Mediterranean diet and a common source of lipids that lowers morbidity and disease severity. This study synthesised two fatty amides from EVOO: hydroxamic fatty acids (FHA) and fatty hydrazide hydrate (FHH). The Density Functional Theory (DFT) was applied to quantum mechanics computation. Nuclear magnetic resonance (NMR), Fourier transforms infrared (FTIR), and element analysis were used to characterise fatty amides. Likewise, the minimum inhibitory concentration (MIC) and timing kill assay were determined. The results revealed that 82 % for FHA and 80 % for FHH conversion were achieved. The amidation reagent/EVOO ratio (mmol: mmol) was 7:1, using the reaction time of 12 h and hexane as an organic solvent. The results further revealed that fatty amides have high antibacterial activity with low concentration at 0.04 μg/mL during eight h of FHA and 0.3 μg/mL during ten h of FHH. This research inferred that FHA and FHH could provide an alternative and effective therapeutic strategy for bacterial diseases. Current findings could provide the basis for the modernisation/introduction of novel and more effective antibacterial drugs derived from natural products.
    Matched MeSH terms: Models, Theoretical*
  9. Lim JT, Maung K, Tan ST, Ong SE, Lim JM, Koo JR, et al.
    PLoS Comput Biol, 2021 May;17(5):e1008959.
    PMID: 34043622 DOI: 10.1371/journal.pcbi.1008959
    Mass gathering events have been identified as high-risk environments for community transmission of coronavirus disease 2019 (COVID-19). Empirical estimates of their direct and spill-over effects however remain challenging to identify. In this study, we propose the use of a novel synthetic control framework to obtain causal estimates for direct and spill-over impacts of these events. The Sabah state elections in Malaysia were used as an example for our proposed methodology and we investigate the event's spatial and temporal impacts on COVID-19 transmission. Results indicate an estimated (i) 70.0% of COVID-19 case counts within Sabah post-state election were attributable to the election's direct effect; (ii) 64.4% of COVID-19 cases in the rest of Malaysia post-state election were attributable to the election's spill-over effects. Sensitivity analysis was further conducted by examining epidemiological pre-trends, surveillance efforts, varying synthetic control matching characteristics and spill-over specifications. We demonstrate that our estimates are not due to pre-existing epidemiological trends, surveillance efforts, and/or preventive policies. These estimates highlight the potential of mass gatherings in one region to spill-over into an outbreak of national scale. Relaxations of mass gathering restrictions must therefore be carefully considered, even in the context of low community transmission and enforcement of safe distancing guidelines.
    Matched MeSH terms: Models, Theoretical*
  10. Tahriri F, Dawal SZ, Taha Z
    ScientificWorldJournal, 2014;2014:505207.
    PMID: 24982962 DOI: 10.1155/2014/505207
    A new multiobjective dynamic fuzzy genetic algorithm is applied to solve a fuzzy mixed-model assembly line sequencing problem in which the primary goals are to minimize the total make-span and minimize the setup number simultaneously. Trapezoidal fuzzy numbers are implemented for variables such as operation and travelling time in order to generate results with higher accuracy and representative of real-case data. An improved genetic algorithm called fuzzy adaptive genetic algorithm (FAGA) is proposed in order to solve this optimization model. In establishing the FAGA, five dynamic fuzzy parameter controllers are devised in which fuzzy expert experience controller (FEEC) is integrated with automatic learning dynamic fuzzy controller (ALDFC) technique. The enhanced algorithm dynamically adjusts the population size, number of generations, tournament candidate, crossover rate, and mutation rate compared with using fixed control parameters. The main idea is to improve the performance and effectiveness of existing GAs by dynamic adjustment and control of the five parameters. Verification and validation of the dynamic fuzzy GA are carried out by developing test-beds and testing using a multiobjective fuzzy mixed production assembly line sequencing optimization problem. The simulation results highlight that the performance and efficacy of the proposed novel optimization algorithm are more efficient than the performance of the standard genetic algorithm in mixed assembly line sequencing model.
    Matched MeSH terms: Models, Theoretical
  11. Abdul Razak F, Jensen HJ
    PLoS One, 2014;9(6):e99462.
    PMID: 24955766 DOI: 10.1371/journal.pone.0099462
    'Causal' direction is of great importance when dealing with complex systems. Often big volumes of data in the form of time series are available and it is important to develop methods that can inform about possible causal connections between the different observables. Here we investigate the ability of the Transfer Entropy measure to identify causal relations embedded in emergent coherent correlations. We do this by firstly applying Transfer Entropy to an amended Ising model. In addition we use a simple Random Transition model to test the reliability of Transfer Entropy as a measure of 'causal' direction in the presence of stochastic fluctuations. In particular we systematically study the effect of the finite size of data sets.
    Matched MeSH terms: Models, Theoretical
  12. Zolhavarieh S, Aghabozorgi S, Teh YW
    ScientificWorldJournal, 2014;2014:312521.
    PMID: 25140332 DOI: 10.1155/2014/312521
    Clustering of subsequence time series remains an open issue in time series clustering. Subsequence time series clustering is used in different fields, such as e-commerce, outlier detection, speech recognition, biological systems, DNA recognition, and text mining. One of the useful fields in the domain of subsequence time series clustering is pattern recognition. To improve this field, a sequence of time series data is used. This paper reviews some definitions and backgrounds related to subsequence time series clustering. The categorization of the literature reviews is divided into three groups: preproof, interproof, and postproof period. Moreover, various state-of-the-art approaches in performing subsequence time series clustering are discussed under each of the following categories. The strengths and weaknesses of the employed methods are evaluated as potential issues for future studies.
    Matched MeSH terms: Models, Theoretical
  13. Magableh A, Shukur Z, Ali NM
    ScientificWorldJournal, 2014;2014:327808.
    PMID: 25136656 DOI: 10.1155/2014/327808
    Unified Modeling Language is the most popular and widely used Object-Oriented modelling language in the IT industry. This study focuses on investigating the ability to expand UML to some extent to model crosscutting concerns (Aspects) to support AspectJ. Through a comprehensive literature review, we identify and extensively examine all the available Aspect-Oriented UML modelling approaches and find that the existing Aspect-Oriented Design Modelling approaches using UML cannot be considered to provide a framework for a comprehensive Aspectual UML modelling approach and also that there is a lack of adequate Aspect-Oriented tool support. This study also proposes a set of Aspectual UML semantic rules and attempts to generate AspectJ pseudocode from UML diagrams. The proposed Aspectual UML modelling approach is formally evaluated using a focus group to test six hypotheses regarding performance; a "good design" criteria-based evaluation to assess the quality of the design; and an AspectJ-based evaluation as a reference measurement-based evaluation. The results of the focus group evaluation confirm all the hypotheses put forward regarding the proposed approach. The proposed approach provides a comprehensive set of Aspectual UML structural and behavioral diagrams, which are designed and implemented based on a comprehensive and detailed set of AspectJ programming constructs.
    Matched MeSH terms: Models, Theoretical
  14. Jawahar N, Ponnambalam SG, Sivakumar K, Thangadurai V
    ScientificWorldJournal, 2014;2014:458959.
    PMID: 24790568 DOI: 10.1155/2014/458959
    Products such as cars, trucks, and heavy machinery are assembled by two-sided assembly line. Assembly line balancing has significant impacts on the performance and productivity of flow line manufacturing systems and is an active research area for several decades. This paper addresses the line balancing problem of a two-sided assembly line in which the tasks are to be assigned at L side or R side or any one side (addressed as E). Two objectives, minimum number of workstations and minimum unbalance time among workstations, have been considered for balancing the assembly line. There are two approaches to solve multiobjective optimization problem: first approach combines all the objectives into a single composite function or moves all but one objective to the constraint set; second approach determines the Pareto optimal solution set. This paper proposes two heuristics to evolve optimal Pareto front for the TALBP under consideration: Enumerative Heuristic Algorithm (EHA) to handle problems of small and medium size and Simulated Annealing Algorithm (SAA) for large-sized problems. The proposed approaches are illustrated with example problems and their performances are compared with a set of test problems.
    Matched MeSH terms: Models, Theoretical
  15. Rahman S, Akib S, Khan MT, Shirazi SM
    ScientificWorldJournal, 2014;2014:729357.
    PMID: 24790578 DOI: 10.1155/2014/729357
    This experimental study was conducted to idealize the efficacy of sea wall in controlling the tsunami forces on onshore structures. Different types of sea walls were placed in front of the building model. The tsunami forces and the wave heights were measured with and without the sea wall conditions. Types of sea wall, wall height, and wall positions were varied simultaneously to quantify the force reductions. Maximum of 41% forces was reduced by higher sea wall, positioned closer proximity to the model whereas this reduction was about 27% when the wall height was half of the high wall. Experimental investigations revealed that wall with adequate height and placed closer to the structures enables a satisfactory predictor of the force reduction on onshore structures. Another set of tests were performed with perforated wall placing near the building model. Less construction cost makes the provision of perforated sea wall interesting. The overall results showed that the efficacy of perforated wall is almost similar to solid wall. Hence, it can be efficiently used instead of solid wall. Moreover, overtopped water that is stuck behind the wall is readily gone back to the sea through perforations releasing additional forces on the nearby structures.
    Matched MeSH terms: Models, Theoretical
  16. Khan FM, Sarmin NH, Khan HU
    ScientificWorldJournal, 2014;2014:275947.
    PMID: 24883375 DOI: 10.1155/2014/275947
    In several advanced fields like control engineering, computer science, fuzzy automata, finite state machine, and error correcting codes, the use of fuzzified algebraic structures especially ordered semigroups plays a central role. In this paper, we introduced a new and advanced generalization of fuzzy generalized bi-ideals of ordered semigroups. These new concepts are supported by suitable examples. These new notions are the generalizations of ordinary fuzzy generalized bi-ideals of ordered semigroups. Several fundamental theorems of ordered semigroups are investigated by the properties of these newly defined fuzzy generalized bi-ideals. Further, using level sets, ordinary fuzzy generalized bi-ideals are linked with these newly defined ideals which is the most significant part of this paper.
    Matched MeSH terms: Models, Theoretical
  17. Hossain MK, Kamil AA, Baten MA, Mustafa A
    PLoS One, 2012;7(10):e46081.
    PMID: 23077500 DOI: 10.1371/journal.pone.0046081
    The objective of this paper is to apply the Translog Stochastic Frontier production model (SFA) and Data Envelopment Analysis (DEA) to estimate efficiencies over time and the Total Factor Productivity (TFP) growth rate for Bangladeshi rice crops (Aus, Aman and Boro) throughout the most recent data available comprising the period 1989-2008. Results indicate that technical efficiency was observed as higher for Boro among the three types of rice, but the overall technical efficiency of rice production was found around 50%. Although positive changes exist in TFP for the sample analyzed, the average growth rate of TFP for rice production was estimated at almost the same levels for both Translog SFA with half normal distribution and DEA. Estimated TFP from SFA is forecasted with ARIMA (2, 0, 0) model. ARIMA (1, 0, 0) model is used to forecast TFP of Aman from DEA estimation.
    Matched MeSH terms: Models, Theoretical
  18. Sadollah A, Bahreininejad A
    J Mech Behav Biomed Mater, 2011 Oct;4(7):1384-95.
    PMID: 21783149 DOI: 10.1016/j.jmbbm.2011.05.009
    Despite dental implantation being a great success, one of the key issues facing it is a mismatch of mechanical properties between engineered and native biomaterials, which makes osseointegration and bone remodeling problematical. Functionally graded material (FGM) has been proposed as a potential upgrade to some conventional implant materials such as titanium for selection in prosthetic dentistry. The idea of an FGM dental implant is that the property would vary in a certain pattern to match the biomechanical characteristics required at different regions in the hosting bone. However, matching the properties does not necessarily guarantee the best osseointegration and bone remodeling. Little existing research has been reported on developing an optimal design of an FGM dental implant for promoting long-term success. Based upon remodeling results, metaheuristic algorithms such as the genetic algorithms (GAs) and simulated annealing (SA) have been adopted to develop a multi-objective optimal design for FGM implantation design. The results are compared with those in literature.
    Matched MeSH terms: Models, Theoretical
  19. Humada AM, Hojabri M, Sulaiman MH, Hamada HM, Ahmed MN
    PLoS One, 2016;11(4):e0152766.
    PMID: 27035575 DOI: 10.1371/journal.pone.0152766
    A grid-connected photovoltaic (PV) system operates under fluctuated weather condition has been modeled and characterized based on specific test bed. A mathematical model of a small-scale PV system has been developed mainly for residential usage, and the potential results have been simulated. The proposed PV model based on three PV parameters, which are the photocurrent, IL, the reverse diode saturation current, Io, the ideality factor of diode, n. Accuracy of the proposed model and its parameters evaluated based on different benchmarks. The results showed that the proposed model fitting the experimental results with high accuracy compare to the other models, as well as the I-V characteristic curve. The results of this study can be considered valuable in terms of the installation of a grid-connected PV system in fluctuated climatic conditions.
    Matched MeSH terms: Models, Theoretical
  20. Ibrahim RW, Ahmad MZ, Al-Janaby HF
    Saudi J Biol Sci, 2016 Jan;23(1):S45-9.
    PMID: 26858564 DOI: 10.1016/j.sjbs.2015.09.012
    A mutation is ultimately essential for adaptive evolution in all populations. It arises all the time, but is mostly fixed by enzymes. Further, most do consider that the evolution mechanism is by a natural assortment of variations in organisms in line for random variations in their DNA, and the suggestions for this are overwhelming. The altering of the construction of a gene, causing a different form that may be communicated to succeeding generations, produced by the modification of single base units in DNA, or the deletion, insertion, or rearrangement of larger units of chromosomes or genes. This altering is called a mutation. In this paper, a mathematical model is introduced to this reality. The model describes the time and space for the evolution. The tool is based on a complex domain for the space. We show that the evolution is distributed with the hypergeometric function. The Boundedness of the evolution is imposed by utilizing the Koebe function.
    Matched MeSH terms: Models, Theoretical
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