Showing papers by "National University of Malaysia published in 2012"

A Review of Smart Homes—Past, Present, and Future

Abstract: A smart home is an application of ubiquitous computing in which the home environment is monitored by ambient intelligence to provide context-aware services and facilitate remote home control. This paper presents an overview of previous smart home research as well as the associated technologies. A brief discussion on the building blocks of smart homes and their interrelationships is presented. It describes collective information about sensors, multimedia devices, communication protocols, and systems, which are widely used in smart home implementation. Special algorithms from different fields and their significance are explained according to their scope of use in smart homes. This paper also presents a concrete guideline for future researchers to follow in developing a practical and sustainable smart home.

The role of oxidative stress and antioxidants in diabetic complications.

Abstract: Diabetes is considered to be one of the most common chronic diseases worldwide. There is a growing scientific and public interest in connecting oxidative stress with a variety of pathological conditions including diabetes mellitus (DM) as well as other human diseases. Previous experimental and clinical studies report that oxidative stress plays a major role in the pathogenesis and development of complications of both types of DM. However, the exact mechanism by which oxidative stress could contribute to and accelerate the development of complications in diabetic mellitus is only partly known and remains to be clarified. On the one hand, hyperglycemia induces free radicals; on the other hand, it impairs the endogenous antioxidant defense system in patients with diabetes. Endogenous antioxidant defense mechanisms include both enzymatic and non-enzymatic pathways. Their functions in human cells are to counterbalance toxic reactive oxygen species (ROS). Common antioxidants include the vitamins A, C, and E, glutathione (GSH), and the enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GRx). This review describes the importance of endogenous antioxidant defense systems, their relationship to several pathophysiological processes and their possible therapeutic implications in vivo.

A review on bio-oil production from biomass by using pyrolysis method

Abstract: The paper provides an updated review on thermal conversion of biomass for the production of liquid products referred as bio-oil. This technology is described focusing on the characterization of feedstock, reactor design, products formation and upgrading. For feedstock characterization is covered in terms of several pretreatment methods. The reactor designs are illustrated number of design ranging from fixed bed to circulating fluidized bed. The properties of bio-oil composition have caused increasingly extensive research to be undertaken to address properties that need modification and this area is reviewed in terms of physical, catalytic and chemical upgrading. The mechanism of the products formation is also illustrated by several chemical routes. Reactor parameters such as heating rate, temperature of pyrolysis, catalysts etc are reviewed.

Antifungal activity of chitosan nanoparticles and correlation with their physical properties.

Abstract: The need of natural antimicrobials is paramount to avoid harmful synthetic chemicals. The study aimed to determine the antifungal activity of natural compound chitosan and its nanoparticles forms against Candida albicans, Fusarium solani and Aspergillus niger. Chitosan nanoparticles were prepared from low (LMW), high molecular weight (HMW) chitosan and its derivative, trimethyl chitosan (TMC). Particle size was increased when chitosan/TMC concentration was increased from 1 to 3 mg/mL. Their zeta potential ranged from +22 to +55 mV. Chitosan nanoparticles prepared from different concentrations of LMW and HMW were also found to serve a better inhibitory activity against C. albicans (MIC(LMW) = 0.25-0.86 mg/mL and MIC(HMW) = 0.6-1.0 mg/mL) and F. solani (MIC(LMW) = 0.86-1.2 mg/mL and MIC(HMW) = 0.5-1.2 mg/mL) compared to the solution form (MIC = 3 mg/mL for both MWs and species). This inhibitory effect was also influenced by particle size and zeta potential of chitosan nanoparticles. Besides, Aspergillus niger was found to be resistant to chitosan nanoparticles except for nanoparticles prepared from higher concentrations of HMW. Antifungal activity of nanoparticles prepared from TMC was negligible. The parent compound therefore could be formulated and applied as a natural antifungal agent into nanoparticles form to enhance its antifungal activity.

Complex intuitionistic fuzzy sets

Abstract: This paper presents a new concept of complex intuitionistic fuzzy set (CIFS) which is generalized from the innovative concept of a complex fuzzy set (CFS) by adding the non-membership term to the definition of CFS. The novelty of CIFS lies in its ability for membership and non-membership functions to achieve more range of values. The ranges of values are extended to the unit circle in complex plane for both membership and non-membership functions instead of [0, 1] as in the conventional intuitionistic fuzzy functions. We define basic operations namely complement, union, and intersection on CIFSs. Properties of these operations are derived.

Trombe walls: A review of opportunities and challenges in research and development

Abstract: Green building and sustainable architecture are new techniques for addressing the environmental and energy crises. Trombe walls are regarded as a sustainable architectural technology for heating and ventilation. This article reviews the application of Trombe walls in buildings. The reviews discuss the characteristics of Trombe walls, including Trombe-wall configurations, and Trombe-wall technology. The advantages and disadvantages of this sustainable architectural technology have been highlighted, and future research questions have been identified.

A review of solar energy modeling techniques

Abstract: Solar radiation data provide information on how much of the sun's energy strikes a surface at a location on the earth during a particular time period. These data are needed for effective research in solar-energy utilization. Due to the cost of and difficulty in solar radiation measurements and these data are not readily available, alternative ways of generating these data are needed. In this paper, a review is made on the solar energy modeling techniques which are classified based on the nature of the modeling technique. Linear, nonlinear, artificial intelligence models for solar energy prediction have been considered in this review. The outcome of the review showed that the sunshine ratio, ambient temperature and relative humidity are the most correlated coefficients to solar energy.

Exploring English language learning and teaching in Malaysia

Abstract: This paper presents a review of recent research that investigates the problem and the practice of English language teaching and learning in Malaysia. The aim of the paper is to identify the factors that contribute to low or limited English literacy achievement among Malaysian learners. A review of these studies indicates a general pattern of dissatisfaction among students, educators, policy makers and the public regarding the teaching and learning of the language (Razianna Abdul Rahman, 2005; Rosemala Ismail, 2008). In addition, studies focusing on English language proficiency among Malaysian university graduates also seem to resonate a feeling of uneasiness with the graduates’ level of English proficiency (Isarji Sarudin et al., 2008). This paper therefore discusses some of the key issues and competing discourses confronting English language learning in this country. It reflects on how the teaching of English is variously conceptualized in our classrooms, raising important questions about the positions of English literacy to Malaysian learners and the society in general.

Lean production supply chain management as driver towards enhancing product quality and business performance

Abstract: Purpose – The purpose of this paper is to obtain a better understanding of the extent to which lean production permeates manufacturing companies in Malaysia by drawing on supply chain management (SCM) managers' or production managers' perception of lean production practices and level of performances in the industryDesign/methodology/approach – The instrument used in this study is a structured survey questionnaire consisting of two major parts The first part comprises several variables measuring lean production practices, and the second part consists of several performance measurements Sample companies are chosen from Malaysian manufacturing companies listed in the Federation of Malaysian Manufacturers directory From the 300 companies sampled, 200 responses were completed, representing a 67 per cent response rateFindings – The results support the conceptual model, demonstrating strong association between lean production, product quality performance, and business performance The structural equation mo

Risk factors for osteoradionecrosis after head and neck radiation: a systematic review.

Abstract: Objective This systematic review aimed to answer the clinical question, “What is the current risk of developing osteoradionecrosis of the jaws among irradiated head and neck cancer patients?” Study Design A systematic review of published English-language randomized controlled trials on the outcome of radiation therapy was performed via Medline and Embase databases. Data on osteoradionecrosis/bone toxicity were collected and analyzed. Results Twenty-two articles reporting on a total of 5,742 patients were selected for final review based on strict eligibility criteria. An estimated 2% of the head and neck–irradiated patients are at risk of developing osteoradionecrosis. Patients receiving adjunctive radiotherapy, accelerated fractionation without dose reduction, and chemoradiotherapy show no increase in osteoradionecrosis risk. Accelerated fractionation with dose reduction is associated with a reduced risk, whereas hyperfractionation shows elevated risk of developing osteoradionecrosis. Conclusions The risk of developing osteoradionecrosis among the irradiated head and neck cancer patient has significantly declined in recent years.

Ultrafiltration in Food Processing Industry: Review on Application, Membrane Fouling, and Fouling Control

Abstract: Ultrafiltration process has been applied widely in food processing industry for the last 20 years due to its advantages over conventional separation processes such as gentle product treatment, high selectivity, and lower energy consumption. Ultrafiltration becomes an essential part in food technology as a tool for separation and concentration. However, membrane fouling compromises the benefits of ultrafiltration as fouling significantly reduces the performance and hence increases the cost of ultrafiltration. Recent advances in this area show the various intensive studies carried out to improve ultrafiltration, focusing on membrane fouling control and cleaning of fouled membranes. Thus, this paper reviews recent developments in ultrafiltration process, focusing on fouling mechanisms of ultrafiltration membranes as well as the latest techniques used to counter membrane fouling.

Planetary Stewardship in an Urbanizing World: Beyond City Limits

Abstract: Cities are rapidly increasing in importance as a major factor shaping the Earth system, and therefore, must take corresponding responsibility. With currently over half the world's population, cities are supported by resources originating from primarily rural regions often located around the world far distant from the urban loci of use. The sustainability of a city can no longer be considered in isolation from the sustainability of human and natural resources it uses from proximal or distant regions, or the combined resource use and impacts of cities globally. The world's multiple and complex environmental and social challenges require interconnected solutions and coordinated governance approaches to planetary stewardship. We suggest that a key component of planetary stewardship is a global system of cities that develop sustainable processes and policies in concert with its non-urban areas. The potential for cities to cooperate as a system and with rural connectivity could increase their capacity to effect change and foster stewardship at the planetary scale and also increase their resource security.

The third national health and morbidity survey: Prevalence of obesity, and abdominal obesity among the Malaysian elderly population

Abstract: Obesity is an emerging public health threat in the elderly population in developing countries. Hence, the Third National Health and Morbidity Survey has assessed 4746 individuals aged 60 years and older recruited through a household survey to determine the prevalence of adiposity using body mass index and waist circumference. The national's prevalence of overweight and obesity in men was 29.2% (95% confidence interval [CI] = 27.2-31.3) and 7.4% (95% CI = 6.4-8.6), respectively. However, the prevalence decreased with age. The figures in women were 30.3% (95% CI = 28.5-32.1) and 13.8% (95% CI = 12.5-15.2), respectively. The prevalence of abdominal obesity was 21.4% (95%CI = 20.2-22.6), with 7.7% (95% CI = 6.7-9.0) in men and 33.4% (95% CI = 31.4-35.3) in women. Predictors of adiposity include the following: Malay and Indian ethnicity, higher education level, higher household income, from urban area, and being married. In conclusion, adiposity affects about one third of the Malaysian elderly population, especially those of the younger age group, women, and those with higher socioeconomic status.

Dementia, stroke, and vascular risk factors; a review

Abstract: Interest in dementia has increased over the past few decades. Stroke is an important cause of cognitive problems. The term vascular cognitive impairment is now used to describe dementia attributed to stroke or deep white matter lesions detected on imaging. Although vascular cognitive impairment is increasingly diagnosed, Alzheimer's disease remains the most common dementia worldwide. The relationship between Alzheimer's disease and vascular cognitive impairment is unclear, although there exists significant overlap, which prompts physicians to consider them opposite ends of a disease spectrum, rather than separate entities. There is also substantial evidence that stroke risk factors such as hypertension, diabetes; lipid disorders, etc. are independently associated with an increased risk of Alzheimer's disease and vascular cognitive impairment. Evidence suggests that these risk factors have a cumulative effect on Alzheimer's disease development but not on vascular cognitive impairment. This is more marked in Alzheimer's disease patients in the presence of the e4 allelic variant of apolipoprotein E. How these risk factors increase the risk of dementia is largely unknown. Physicians must be aware that stroke causes dementia; that vascular risk factors appear to be independent risk factors in developing dementia, and that poststroke care must include cognitive assessment.

A combined approach for clustering based on K-means and gravitational search algorithms

Abstract: Clustering is an attractive and important task in data mining that is used in many applications. Clustering refers to grouping together data objects so that objects within a cluster are similar to one another, while objects in different clusters are dissimilar. K-means is a simple and efficient algorithm that is widely used for data clustering. However, its performance depends on the initial state of centroids and may trap in local optima. The gravitational search algorithm (GSA) is one effective method for searching problem space to find a near optimal solution. In this paper, we present a hybrid data clustering algorithm based on GSA and k-means (GSA-KM), which uses the advantages of both algorithms. The GSA-KM algorithm helps the k-means algorithm to escape from local optima and also increases the convergence speed of the GSA algorithm. We compared the performance of GSA-KM with other well-known algorithms, including k-means, genetic algorithm (GA), simulated annealing (SA), ant colony optimization (ACO), honey bee mating optimization (HBMO), particle swarm optimization (PSO) and gravitational search algorithm (GSA). Five real and standard datasets from the UCI repository have been used to demonstrate the results of the algorithms. The experimental results are encouraging in terms of the quality of the solutions and the convergence speed of the proposed algorithm.

A review on the role of materials science in solar cells

Abstract: The demand for energy of modern society is constantly increasing. The desire for environmental-friendly alternative energy resources with the least dependency on fossil fuels is growing. Solar energy is an important technology for many reasons and is worthy of urgent attention. Indeed, it has experienced rapid growth over the last few years. It is expected to become truly main stream when the breakeven of high performance is achieved and its cost becomes comparable with other energy sources. Various approaches have been proposed to enhance the efficiency of solar cells. This paper reviews some current initiatives and critical issues on the efficiency improvement of solar cells from the material sciences and chemistry perspectives.