Displaying publications 21 - 40 of 735 in total

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  1. A comparative study on the membrane based palm oil mill effluent (POME) treatment plant
    Ahmad AL, Chong MF, Bhatia S
    J Hazard Mater, 2009 Nov 15;171(1-3):166-74.
    PMID: 19573986 DOI: 10.1016/j.jhazmat.2009.05.114
    The discharge of palm oil mill effluent (POME) causes serious pollution problems and the membrane based POME treatment is suggested as a solution. Three different designs, namely Design A, B and C distinguished by their different types and orientations of membrane system are proposed. The results at optimum condition proved that the quality of the recovered water for all the designs met the effluent discharge standards imposed by the Department of Environment (DOE). The economic analysis at the optimum condition shows that the total treatment cost for Design A was the highest (RM 115.11/m(3)), followed by Design B (RM 23.64/m(3)) and Design C (RM 7.03/m(3)). In this study, the membrane system operated at high operating pressure with low membrane unit cost is preferable. Design C is chosen as the optimal design for the membrane based POME treatment system based on the lowest total treatment cost.
    Matched MeSH terms: Models, Theoretical
  2. Fulltext A comprehensive propagation prediction model comprising microfacet based scattering and probability based coverage optimization algorithm
    Kausar AS, Reza AW, Wo LC, Ramiah H
    ScientificWorldJournal, 2014;2014:601729.
    PMID: 25202733 DOI: 10.1155/2014/601729
    Although ray tracing based propagation prediction models are popular for indoor radio wave propagation characterization, most of them do not provide an integrated approach for achieving the goal of optimum coverage, which is a key part in designing wireless network. In this paper, an accelerated technique of three-dimensional ray tracing is presented, where rough surface scattering is included for making a more accurate ray tracing technique. Here, the rough surface scattering is represented by microfacets, for which it becomes possible to compute the scattering field in all possible directions. New optimization techniques, like dual quadrant skipping (DQS) and closest object finder (COF), are implemented for fast characterization of wireless communications and making the ray tracing technique more efficient. In conjunction with the ray tracing technique, probability based coverage optimization algorithm is accumulated with the ray tracing technique to make a compact solution for indoor propagation prediction. The proposed technique decreases the ray tracing time by omitting the unnecessary objects for ray tracing using the DQS technique and by decreasing the ray-object intersection time using the COF technique. On the other hand, the coverage optimization algorithm is based on probability theory, which finds out the minimum number of transmitters and their corresponding positions in order to achieve optimal indoor wireless coverage. Both of the space and time complexities of the proposed algorithm surpass the existing algorithms. For the verification of the proposed ray tracing technique and coverage algorithm, detailed simulation results for different scattering factors, different antenna types, and different operating frequencies are presented. Furthermore, the proposed technique is verified by the experimental results.
    Matched MeSH terms: Models, Theoretical*
  3. A comprehensive review of milk fouling on heated surfaces
    Sadeghinezhad E, Kazi SN, Dahari M, Safaei MR, Sadri R, Badarudin A
    Crit Rev Food Sci Nutr, 2015;55(12):1724-43.
    PMID: 24731003 DOI: 10.1080/10408398.2012.752343
    Heat exchanger performance degrades rapidly during operation due to formation of deposits on heat transfer surfaces which ultimately reduces service life of the equipment. Due to scaling, product deteriorates which causes lack of proper heating. Chemistry of milk scaling is qualitatively understood and the mathematical models for fouling at low temperatures have been produced but the behavior of systems at ultra high temperature processing has to be studied further to understand in depth. In diversified field, the effect of whey protein fouling along with pressure drop in heat exchangers were conducted by many researchers. Adding additives, treatment of heat exchanger surfaces and changing of heat exchanger configurations are notable areas of investigation in milk fouling. The present review highlighted information about previous work on fouling, influencing parameters of fouling and its mitigation approach and ends up with recommendations for retardation of milk fouling and necessary measures to perform the task.
    Matched MeSH terms: Models, Theoretical
  4. Fulltext A control chart based on cluster-regression adjustment for retrospective monitoring of individual characteristics
    Ong HC, Alih E
    PLoS One, 2015;10(4):e0125835.
    PMID: 25923739 DOI: 10.1371/journal.pone.0125835
    The tendency for experimental and industrial variables to include a certain proportion of outliers has become a rule rather than an exception. These clusters of outliers, if left undetected, have the capability to distort the mean and the covariance matrix of the Hotelling's T2 multivariate control charts constructed to monitor individual quality characteristics. The effect of this distortion is that the control chart constructed from it becomes unreliable as it exhibits masking and swamping, a phenomenon in which an out-of-control process is erroneously declared as an in-control process or an in-control process is erroneously declared as out-of-control process. To handle these problems, this article proposes a control chart that is based on cluster-regression adjustment for retrospective monitoring of individual quality characteristics in a multivariate setting. The performance of the proposed method is investigated through Monte Carlo simulation experiments and historical datasets. Results obtained indicate that the proposed method is an improvement over the state-of-art methods in terms of outlier detection as well as keeping masking and swamping rate under control.
    Matched MeSH terms: Models, Theoretical*
  5. Fulltext A fast density-based clustering algorithm for real-time Internet of Things stream
    Amini A, Saboohi H, Wah TY, Herawan T
    ScientificWorldJournal, 2014;2014:926020.
    PMID: 25110753 DOI: 10.1155/2014/926020
    Data streams are continuously generated over time from Internet of Things (IoT) devices. The faster all of this data is analyzed, its hidden trends and patterns discovered, and new strategies created, the faster action can be taken, creating greater value for organizations. Density-based method is a prominent class in clustering data streams. It has the ability to detect arbitrary shape clusters, to handle outlier, and it does not need the number of clusters in advance. Therefore, density-based clustering algorithm is a proper choice for clustering IoT streams. Recently, several density-based algorithms have been proposed for clustering data streams. However, density-based clustering in limited time is still a challenging issue. In this paper, we propose a density-based clustering algorithm for IoT streams. The method has fast processing time to be applicable in real-time application of IoT devices. Experimental results show that the proposed approach obtains high quality results with low computation time on real and synthetic datasets.
    Matched MeSH terms: Models, Theoretical*
  6. A finite element model to predict wellbore fracture pressure with acid damage
    Fanhui-Zeng, Jianchun-Guo, Yuxuan-Liu
    Sains Malaysiana, 2015;44:1377-1388.
    Hydraulic fracturing becomes more difficult when confronted with a formation of high fracturing pressure. In such formations, acidizing before the main fracturing treatment provide a method to reduce fracture pressure. The aim of this paper was to investigate the evolution of fracture pressure in a wellbore with acidizing. Five experiments were conducted to study the mechanisms of acid damage on reservoir minerals and cementing materials properties. Consequently, a mathematical model to predict fracture pressure with acidizing has been established and verified by field data. The analysis results showed that it is possible to reduce fracture pressure with decreased rock strength and fracture critical stress intensity factor by means of acid damage. Acid damage destroys the crystal structure of mineral particles, breaks the crystalline layers in cementing materials, increases rock porosity and reduces the rock strength. In addition, as the acid concentration, formation temperature and acid treatment time increased, it was useful to reduce fracture pressure in the wellbore. Using the proposed model, we were able to select the optimal acid damage construction parameters to reduce fracture pressure.
    Matched MeSH terms: Models, Theoretical
  7. A fuzzy logic control in adjustable autonomy of a multi-agent system for an automated elderly movement monitoring application
    Mostafa SA, Mustapha A, Mohammed MA, Ahmad MS, Mahmoud MA
    Int J Med Inform, 2018 04;112:173-184.
    PMID: 29500017 DOI: 10.1016/j.ijmedinf.2018.02.001
    Autonomous agents are being widely used in many systems, such as ambient assisted-living systems, to perform tasks on behalf of humans. However, these systems usually operate in complex environments that entail uncertain, highly dynamic, or irregular workload. In such environments, autonomous agents tend to make decisions that lead to undesirable outcomes. In this paper, we propose a fuzzy-logic-based adjustable autonomy (FLAA) model to manage the autonomy of multi-agent systems that are operating in complex environments. This model aims to facilitate the autonomy management of agents and help them make competent autonomous decisions. The FLAA model employs fuzzy logic to quantitatively measure and distribute autonomy among several agents based on their performance. We implement and test this model in the Automated Elderly Movements Monitoring (AEMM-Care) system, which uses agents to monitor the daily movement activities of elderly users and perform fall detection and prevention tasks in a complex environment. The test results show that the FLAA model improves the accuracy and performance of these agents in detecting and preventing falls.
    Matched MeSH terms: Models, Theoretical*
  8. Fulltext A generalized quantum-inspired decision making model for intelligent agent
    Hu Y, Loo CK
    ScientificWorldJournal, 2014;2014:240983.
    PMID: 24778580 DOI: 10.1155/2014/240983
    A novel decision making for intelligent agent using quantum-inspired approach is proposed. A formal, generalized solution to the problem is given. Mathematically, the proposed model is capable of modeling higher dimensional decision problems than previous researches. Four experiments are conducted, and both empirical experiments results and proposed model's experiment results are given for each experiment. Experiments showed that the results of proposed model agree with empirical results perfectly. The proposed model provides a new direction for researcher to resolve cognitive basis in designing intelligent agent.
    Matched MeSH terms: Models, Theoretical*
  9. A global strategy for road building
    Laurance WF, Clements GR, Sloan S, O'Connell CS, Mueller ND, Goosem M, et al.
    Nature, 2014 Sep 11;513(7517):229-32.
    PMID: 25162528 DOI: 10.1038/nature13717
    The number and extent of roads will expand dramatically this century. Globally, at least 25 million kilometres of new roads are anticipated by 2050; a 60% increase in the total length of roads over that in 2010. Nine-tenths of all road construction is expected to occur in developing nations, including many regions that sustain exceptional biodiversity and vital ecosystem services. Roads penetrating into wilderness or frontier areas are a major proximate driver of habitat loss and fragmentation, wildfires, overhunting and other environmental degradation, often with irreversible impacts on ecosystems. Unfortunately, much road proliferation is chaotic or poorly planned, and the rate of expansion is so great that it often overwhelms the capacity of environmental planners and managers. Here we present a global scheme for prioritizing road building. This large-scale zoning plan seeks to limit the environmental costs of road expansion while maximizing its benefits for human development, by helping to increase agricultural production, which is an urgent priority given that global food demand could double by mid-century. Our analysis identifies areas with high environmental values where future road building should be avoided if possible, areas where strategic road improvements could promote agricultural development with relatively modest environmental costs, and 'conflict areas' where road building could have sizeable benefits for agriculture but with serious environmental damage. Our plan provides a template for proactively zoning and prioritizing roads during the most explosive era of road expansion in human history.
    Matched MeSH terms: Models, Theoretical
  10. A glycerol-free process to produce biodiesel by supercritical methyl acetate technology: an optimization study via Response Surface Methodology
    Tan KT, Lee KT, Mohamed AR
    Bioresour Technol, 2010 Feb;101(3):965-9.
    PMID: 19773156 DOI: 10.1016/j.biortech.2009.09.004
    In this study, fatty acid methyl esters (FAME) have been successfully produced from transesterification reaction between triglycerides and methyl acetate, instead of alcohol. In this non-catalytic supercritical methyl acetate (SCMA) technology, triacetin which is a valuable biodiesel additive is produced as side product rather than glycerol, which has lower commercial value. Besides, the properties of the biodiesel (FAME and triacetin) were found to be superior compared to those produced from conventional catalytic reactions (FAME only). In this study, the effects of various important parameters on the yield of biodiesel were optimized by utilizing Response Surface Methodology (RSM) analysis. The mathematical model developed was found to be adequate and statistically accurate to predict the optimum yield of biodiesel. The optimum conditions were found to be 399 degrees C for reaction temperature, 30 mol/mol of methyl acetate to oil molar ratio and reaction time of 59 min to achieve 97.6% biodiesel yield.
    Matched MeSH terms: Models, Theoretical
  11. A grounded explanation of why women present with advanced breast cancer
    Taib NA, Yip CH, Low WY
    World J Surg, 2014 Jul;38(7):1676-84.
    PMID: 24280975 DOI: 10.1007/s00268-013-2339-4
    Advanced breast cancer presentation remains a large obstacle in lowering mortality rates in low- and middle-resource countries. This study aims to explore the reasons why women present with breast cancer at an advanced stage.
    Matched MeSH terms: Models, Theoretical
  12. A hazard rate analysis of fertility using duration data from Malaysia
    Chang C
    Res Popul Econ, 1988;6:137-59.
    PMID: 12280927
    Matched MeSH terms: Models, Theoretical*
  13. Fulltext A high-speed and low-offset dynamic latch comparator
    Rahman LF, Bin Ibne Reaz M, Yin CC, Marufuzzaman M, Rahman MA
    ScientificWorldJournal, 2014;2014:258068.
    PMID: 25114959 DOI: 10.1155/2014/258068
    Circuit intricacy, speed, low-offset voltage, and resolution are essential factors for high-speed applications like analog-to-digital converters (ADCs). The comparator circuit with preamplifier increases the power dissipation, as it requires higher amount of currents than the latch circuitry. In this research, a novel topology of dynamic latch comparator is illustrated, which is able to provide high speed, low offset, and high resolution. Moreover, the circuit is able to reduce the power dissipation as the topology is based on latch circuitry. The cross-coupled circuit mechanism with the regenerative latch is employed for enhancing the dynamic latch comparator performance. In addition, input-tracking phase is used to reduce the offset voltage. The Monte-Carlo simulation results for the designed comparator in 0.18 μm CMOS process show that the equivalent input-referred offset voltage is 720 μV with 3.44 mV standard deviation. The simulated result shows that the designed comparator has 8-bit resolution and dissipates 158.5 μW of power under 1.8 V supply while operating with a clock frequency of 50 MHz. In addition, the proposed dynamic latch comparator has a layout size of 148.80 μm × 59.70 μm.
    Matched MeSH terms: Models, Theoretical*
  14. A hybrid ART-GRNN online learning neural network with a epsilon -insensitive loss function
    Yap KS, Lim CP, Abidin IZ
    IEEE Trans Neural Netw, 2008 Sep;19(9):1641-6.
    PMID: 18779094 DOI: 10.1109/TNN.2008.2000992
    In this brief, a new neural network model called generalized adaptive resonance theory (GART) is introduced. GART is a hybrid model that comprises a modified Gaussian adaptive resonance theory (MGA) and the generalized regression neural network (GRNN). It is an enhanced version of the GRNN, which preserves the online learning properties of adaptive resonance theory (ART). A series of empirical studies to assess the effectiveness of GART in classification, regression, and time series prediction tasks is conducted. The results demonstrate that GART is able to produce good performances as compared with those of other methods, including the online sequential extreme learning machine (OSELM) and sequential learning radial basis function (RBF) neural network models.
    Matched MeSH terms: Models, Theoretical*
  15. A market modeling review study on predicting Malaysian consumer behavior towards widespread adoption of PHEV/EV
    Adnan N, Nordin SM, Rahman I, Amini MH
    Environ Sci Pollut Res Int, 2017 Aug;24(22):17955-17975.
    PMID: 28612311 DOI: 10.1007/s11356-017-9153-8
    With the rising concern about climate change, there has been an increased public awareness that has resulted in new government policies to support scientific research for mitigating these problems. Malaysia is among the major energy-intense countries and is under an excessive burden to advance its energy efficiency and to also work towards the reduction of its carbon emission. Plug-in hybrid electric vehicles (PHEVs) have the potential to lessen the carbon emission and gasoline consumption in order to alleviate environmental problems. Most of the energy problems linked to the increasing transportation pollution are now being reduced with the solution of the adoption of PHEVs. PHEVs are seen as a solution to cut carbon emission, which prevents environmental damages. Furthermore, PHEVs' driving range and performance can be comparable to the other hybrid vehicles as well as the conventional IC engines that have gasoline and diesel tanks. Thus, many efforts are being initiated to promote the use of PHEVs as an innovative and affordable transportation system. In order to achieve making the consumers aware of the adoption of PHEVs, we used a model which is based on the extended theory of planned behavior (TPB). This review is based on the factors affecting the adoption of PHEVs among Malaysian consumers. The model takes into account the ten key features that influence the adoption of PHEVs, such as environmental concern, personal norm, attitude, vehicle ownership costs, driving range, charging time, intention, subjective norm, perceived behavioral control, and personal norm. All these constructs are drivers towards the adoption of PHEVs. These factors affect the relationship between the adoption of PHEVs and how consumers intend to protect the environment. This review is based on improving how the "attitude-action" gap is understood as it is an important element for further studies on PHEVs. The aim of the research is to come up with a framework that examines how to modify the consumer's environmental concerns in acquiring PHEVs. This will pave the way for more academic research and future works that can emphasize how to obtain empirical results. The authors' recommendation is that, before a consumer's behavior is assessed and considered, an observation of the current technology is needed with methods and knowledge of the existing technology adoption aspect.
    Matched MeSH terms: Models, Theoretical
  16. A mathematical framework for minimally invasive tumor ablation therapies
    Hall SK, Ooi EH, Payne SJ
    Crit Rev Biomed Eng, 2014;42(5):383-417.
    PMID: 25745803
    Minimally invasive tumor ablations (MITAs) are an increasingly important tool in the treatment of solid tumors across multiple organs. The problems experienced in modeling different types of MITAs are very similar, but the development of mathematical models is mostly performed in isolation according to modality. Fundamental research into the modeling of specific types of MITAs is indeed required, but to choose the optimal treatment for an individual the primary clinical requirement is to have reliable predictions for a range of MITAs. In this review of the mathematical modeling of MITAs 4 modalities are considered: radiofrequency ablation, microwave ablation, cryoablation, and irreversible electroporation. The similarities in the mathematical modeling of these treatments are highlighted, and the analysis of the models within a general framework is discussed. This will aid in developing a deeper understanding of the sensitivity of MITA models to physiological parameters and the impact of uncertainty on predictions of the ablation zone. Through robust validation and analysis of the models it will be possible to choose the best model for a given application. This is important because many different models exist with no objective comparison of their performance. The collection of relevant in vivo experimental data is also critical to parameterize such models accurately. This approach will be necessary to translate the field into clinical practice.
    Matched MeSH terms: Models, Theoretical*
  17. Fulltext A mathematical model of healthy diet menu plan for MARA Junior Science College boarding schools
    Nurly Diana Jalil, Maslin Masrom, Wan Normeza Wan Zakaria
    Journal of Advanced Research Design, 2017;33(1):8-14.
    MyJurnal
    Adolescents need more attention on eating habits as they go through a critical path
    period of physical, physiological and psychological changes from children to adult.
    Therefore, planning a proper healthy diet menu is important to adolescents to have
    the sufficient nutrients for proper growth. However, manually plan healthy diet menu
    is complicated, inefficient and time-consuming. The purpose of this study is to develop
    a mathematical model of healthy diet menu plan that minimizes the daily fat intake
    and meets the necessary nutrient intake for adolescents aged 13 between 17 years old
    within the budget provided by Majlis Amanah Rakyat (MARA) for Malaysia adolescent
    in MARA Junior Science College (MJSC) boarding schools. Optimization approach and
    binary integer programming method were used to address the diet problem in this
    study. The finding of the study indicates that the developed mathematical model of
    healthy diet menu plan for MJSC can generate menu plan that minimizes the total fat
    intake at minimum level of requirement per day. This menu plan can be used as a
    guideline for the management of the boarding schools to provide healthy diet meals
    for their students.
    Matched MeSH terms: Models, Theoretical
  18. Fulltext A metamodel for mobile forensics investigation domain
    Ali A, Abd Razak S, Othman SH, Mohammed A, Saeed F
    PLoS One, 2017;12(4):e0176223.
    PMID: 28445486 DOI: 10.1371/journal.pone.0176223
    With the rapid development of technology, mobile phones have become an essential tool in terms of crime fighting and criminal investigation. However, many mobile forensics investigators face difficulties with the investigation process in their domain. These difficulties are due to the heavy reliance of the forensics field on knowledge which, although a valuable resource, is scattered and widely dispersed. The wide dispersion of mobile forensics knowledge not only makes investigation difficult for new investigators, resulting in substantial waste of time, but also leads to ambiguity in the concepts and terminologies of the mobile forensics domain. This paper developed an approach for mobile forensics domain based on metamodeling. The developed approach contributes to identify common concepts of mobile forensics through a development of the Mobile Forensics Metamodel (MFM). In addion, it contributes to simplifying the investigation process and enables investigation teams to capture and reuse specialized forensic knowledge, thereby supporting the training and knowledge management activities. Furthermore, it reduces the difficulty and ambiguity in the mobile forensics domain. A validation process was performed to ensure the completeness and correctness of the MFM. The validation was conducted using two techniques for improvements and adjustments to the metamodel. The last version of the adjusted metamodel was named MFM 1.2.
    Matched MeSH terms: Models, Theoretical*
  19. A model for community participation in breast cancer prevention in Iran
    Ahmadian M, Samah AA
    Asian Pac J Cancer Prev, 2012;13(5):2419-23.
    PMID: 22901232
    CONTEXT: Genuine community participation does not denote taking part in an action planned by health care professionals in a medical or top-down approach. Further, community participation and health education on breast cancer prevention are not similar to other activities incorporated in primary health care services in Iran.

    OBJECTIVE: To propose a model that provides a methodological tool to increase women's participation in the decision making process towards breast cancer prevention. To address this, an evaluation framework was developed that includes a typology of community participation approaches (models) in health, as well as five levels of participation in health programs proposed by Rifkin (1985 and 1991).

    METHOD: This model explains the community participation approaches in breast cancer prevention in Iran. In a 'medical approach', participation occurs in the form of women's adherence to mammography recommendations. As a 'health services approach', women get the benefits of a health project or participate in the available program activities related to breast cancer prevention. The model provides the five levels of participation in health programs along with the 'health services approach' and explains how to implement those levels for women's participation in available breast cancer prevention programs at the local level.

    CONCLUSION: It is hoped that a focus on the 'medical approach' (top-down) and the 'health services approach' (top-down) will bring sustainable changes in breast cancer prevention and will consequently produce the 'community development approach' (bottom-up). This could be achieved using a comprehensive approach to breast cancer prevention by combining the individual and community strategies in designing an intervention program for breast cancer prevention.

    Matched MeSH terms: Models, Theoretical*
  20. A model of the demand for medical and health services in Peninsular Malaysia
    Heller PS
    Soc Sci Med, 1982;16(3):267-84.
    PMID: 7100978 DOI: 10.1016/0277-9536(82)90337-9
    This paper provides an empirical analysis of the determinants of the demand for medical services in Peninsular Malaysia. After elaborating a theoretical model of household demand for medical care in Section II an econometric model is specified and estimated in Sections III, IV, and V. The results indicate that total medical demand, as measured by the absolute volume of outpatient and inpatient consumption, is highly inelastic to the cash price and to the cost in time of utilization. Total medical demand is also inelastic with respect to income. Yet consumers are clearly responsive to the relative prices of alternative sources of medical care. Consumers are also sensitive to the way in which the time of utilization is spent, with high travel and treatment time causing reduced demand for services.
    Matched MeSH terms: Models, Theoretical*
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