19672 research outputs found
Sort by
Algorithm in the fluidized-bed reactor for the polymerization of propylene
No full textA modified artificial bee optimization is proposed in this study. The algorithm is based on the colony behavior of certain bee species to achieve optimal solution in the bounded environment. The proposed algorithm is designed by improving the exploration knowledge of onlooker bee from meta-heuristic concept in search space. The multiple searches is proposed in the exploration phase to evaluate the multi objective functions. The performance of the proposed algorithm is tested on the typical benchmark equations and complex case of the polymerization of propylene in fluidized bed reactor. The proposed technique is able to provide an optimal solutions and it shows a good performance in term of convergence, accuracy and computational load
Public perception and attitude towards dengue prevention activity and response to dengue early warning in Malaysia
No full textAn early warning system for dengue is meant to predict outbreaks and prevent dengue cases by aiding timely decision making and deployment of interventions. However, only a system which is accepted and utilised by the public would be sustainable in the long run. This study aimed to explore the perception and attitude of the Malaysian public towards a dengue early warning system. The sample consisted of 847 individuals who were 18 years and above and living/working in the Petaling District, an area adjacent to Kuala Lumpur, Malaysia. A questionnaire consisting of personal information and three sub-measures of; i) perception, ii) attitude towards dengue early warning and iii) response towards early warning; was distributed to participants. We found that most of the respondents know about dengue fever (97.1%) and its association with climate factors (90.6%). Most of them wanted to help reduce the number of dengue cases in their area (91.5%). A small percentage of the respondents admitted that they were not willing to be involved in public activities, and 64% of them admitted that they did not check dengue situations or hotspots around their area regularly. Despite the high awareness on the relationship between climate and dengue, about 45% of respondents do not know or are not sure how this can be used to predict dengue. Respondents would like to know more about how climate data can be used to predict a dengue outbreak (92.7%). Providing more information on how climate can influence dengue cases would increase public acceptability and improve response towards climatebased warning system. The most preferred way of communicating early warning was through the television (66.4%). This study shows that the public in Petaling District considers it necessary to have a dengue warning system to be necessary, but more education is required
Islamic religiosity and Islamic financial asset holdings (IFAH)
No full textPurpose: This paper aims to examine the relationship between Islamic religiosity and Islamic financial asset holdings (IFAH) among Muslim individuals in Malaysia. Design/methodology/approach: Data for this study were collected through a survey questionnaire, and a sample of 751 working Muslims in Kuala Lumpur was obtained. Islamic religiosity was measured via religiosity levels and religiosity dimensions. IFAH was measured as the fraction of Islamic financial assets held in a financial portfolio. A generalized linear model (GLM) was used to estimate the relationships. Findings: The results show that religiosity level influences the IFAH. Devout Muslims held more Islamic financial assets than casual Muslims. All religiosity dimensions influenced IFAH, with faith having the greatest influence and virtues the least. Educational level strongly influenced IFAH. Research limitations/implications: The sample consisted of working Muslims in Kuala Lumpur; hence, generalization cannot be made to all Malaysian Muslims. This study only focused on Islamic financial assets and did not consider other types of Islamic financial products, such as financing. Practical implications: Efforts to encourage Muslims to opt for Islamic financial assets may be more effective if they begin from the core of religious education. Educating individuals on Islamic principles, including the values and concepts of Islamic finance, is important to encourage the Islamic banking industry to prosper among Muslims. Originality/value: The paper provides an extension of current literature on spirituality and religion by incorporating a comprehensive measure of Islamic religiosity and its relationship with financial asset holdings
UASFF start-up for biohydrogen and biomethane production from treatment of Palm Oil Mill Effluent
No full textA start-up study was conducted to produce biohydrogen and biomethane from Palm Oil Mill Effluent (POME) using a two-stage up-flow anaerobic sludge fixed-film (UASFF) bioreactor. 100% molasses was used to start the system, and POME was added at 10% increments until it reached 100% after 59 days. During this period of continuous operation, the HRT and temperature were adjusted in order to optimize the condition for biogas production. Hydrogen and methane gas production fluctuated between 53–70% and 90–95%, respectively, in the last four days of operation (days 56–59), with POME percentage being increased from 70% to 100% (30%–0% molasses). Using 100% raw POME led to a total COD removal of 83.70%, average gas production rates of 5.29 L H2 d−1 (57.11% H2) and 9.60 L CH4 d−1 (94.08% CH4), in their respective units. This output is comparable to, if not better than using 100% molasses as substrate. This work concludes that based on the relative consistency of biogas production on days 56–59, the two-stage UASFF bioreactor operating at a final HRT of 4 h and temperature of 43 °C has taken a period of two months for start-up
Photovoltaic Flyback Microinverter With Tertiary Winding Current Sensing
No full textThis paper presents a new low cost, non-invasive, and isolated current sensing technique for the grid-tied photovoltaic (PV) flyback microinverter. This is accomplished by using the flyback transformer itself as a current sensor, achieved by introducing a tertiary winding to the flyback transformer. The mathematical integration of the tertiary winding's open circuit voltage through a ground-clamped-integrator results in the sensing of the magnetizing current. Since the magnetizing current is a combination of both primary and secondary current, control of both grid current and maximum power point tracking (MPPT) is implemented by sensing only the magnetizing current. This allows the PV, primary, secondary, and the grid current loops to be free of any invasive current sensors. Moreover, controlling the magnetizing current provides an alternative solution to an inherent problem with continuous conduction mode (CCM), the control complexity. Linear ramping and de-ramping of the magnetizing current allows for a set-reset hysteresis control to be implemented, resulting in CCM control simplicity that is akin to the boundary and discontinuous conduction mode. A grid-tied microinverter prototype is presented for verification, achieving the following experimental result: 1.9% grid current THD, 0.9988 power factor, above 99% static MPPT efficiency and dynamic efficiency of 98.50%
Report of the forth Asian Prostate Cancer (A-CaP) study meeting
No full textThe Asian Prostate Cancer (A-CaP) Study is an Asia-wide prospective registry study for surveying the treatment outcome of prostate cancer patients who have received a histopathological diagnosis. The study aims to clarify the clinical situation for prostate cancer in Asia and use the outcomes for the purposes of international comparison. Following the first meeting in Tokyo on December 2015, the second meeting in Seoul, Korea 2016, the third meeting in Chiang Mai, Thailand, on October 2017, the fourth meeting was held in Seoul, again on August 2018 with the participation of members and collaborators from 13 countries and regions. In the meeting, participating countries and regions presented the current status of data collection and the A-CaP office presented a preliminary analysis of the registered cases received from each country and region. Participants discussed ongoing challenges relating to data cleaning and data updating which is the next step of the A-CaP study following the data collection phase between 2016 and 2018. There was specific difference in term of the patient characteristics, and initial treatment pattern among East Asia, Southeast Asia and Turkey, and Jordan. Finally, a close relationship between prevalence of PSA test and disease stage of the patients at diagnosis in Japan and Malaysia was discussed
Classification of strategies for solving programming problems using Aol sequence analysis
No full textThis eye tracking study examines participants’ visual attention when solving algorithmic problems in the form of programming problems. The stimuli consisted of a problem statement, example output, and a set of multiple-choice questions regarding variables, data types, and operations needed to solve the programming problems. We recorded eye movements of students and performed an Area of Interest (AoI) sequence analysis to identify reading strategies in terms of participants’ performance and visual effort. Using classical eye tracking metrics and a visual AoI sequence analysis we identified two main groups of participants—effective and ineffective problem solvers. This indicates that diversity of participants’ mental schemas leads to a difference in their performance. Therefore, identifying how participants’ reading behavior varies at a finer level of granularity warrants further investigation
Model selection based on value-at-risk backtests approach for GARCH-type models
Get PDFThis paper aims to investigate the efficiency of the value-at-risk (VaR) backtests in the model selection from different types of generalised autoregressive conditional heteroskedasticity (GARCH) models with skewed and non-skewed innovation distributions. Extensive simulation is carried out to compare the model selection based on VaR backtests and Akaike Information Criteria (AIC). When the model is given but the innovation distribution is one of the six selected distributions which may be skewed or non-skewed, the simulation results show that both AIC and the VaR backtests succeed in selecting the correct innovation distribution from the set of six distributions under consideration. This indicates that both AIC and the VaR backtests are able to distinguish between skewed and non-skewed distributions when the innovation distribution is misspecified. Using an empirical data from NASDAQ index, we observe that the selected combination of model and innovation distribution based on the smallest AIC does not agree with that selected by using the in-sample VaR backtests. Examination of confidence limits for VaR and the expected shortfall forecasts under various loss functions provides evidence that the selected combination of model and innovation distribution using the VaR backtests tends to possess smaller mean absolute percentage error and logarithmic loss
Mangrove Oyster (Crassostrea belcheri) as a Biomonitor Species for Bioavailability of Polycyclic Aromatic Hydrocarbons (PAHs) from Sediment of the West Coast of Peninsular Malaysia
No full textRapid industrialization and urbanization in the west coast of Peninsular Malaysia has caused increasing pollution particularly of petroleum and petroleum by-products. Surface sediment and mangrove oyster (Crassostrea belcheri) were collected from five mangrove ecosystems in the west coast of Peninsular Malaysia and investigated for bioavailability of polycyclic aromatic hydrocarbons (PAHs). Sampling locations were selected from both remote areas with few or no previous records of petroleum pollution such as Pulau Merambong and polluted areas that are under international attention such as Klang mangrove ecosystem. PAH fractions were obtained through soxhlet extraction and two-step column chromatography and the fractions were injected to gas chromatography-mass spectrometry (GC-MS) for analysis. The concentrations of PAHs ranged from 151 to 4973 ng g−1 dw in the sediments, while from 309 to 2225 ng g−1 dw in the oysters. When tested for diagnostic ratios, a predominance of pyrogenic source PAHs was detected in the sediments, whereas PAHs in the oysters had mixed petrogenic and pyrogenic sources. A significant correlation (p < 0.05) was found between high molecular weight (HMW) PAHs in the sediments and oysters and biota accumulation factors (BAFs) of PAHs were approaching or exceeding unity indicating the ability of mangrove oyster in bioaccumulation of PAHs. Overall, this study indicates that mangrove oyster (C. belcheri) can be used as a biomonitor species for PAHs in an aquatic environment. © 2017, © 2017 Taylor & Francis Group, LLC
The economic potential of the African iron-ore tailings: synthesis of magnetite for the removal of trace metals in groundwater—a review
No full textAfrica has the second largest ultimately recoverable resources (URR) of gigaton (Gt) iron (Fe) ore in the world. South Africa is among the countries in the world with high-quality iron ore deposits. The most significant sources of Fe ore in the African continent are hosted by the banded iron ore formation of Precambrian age with high-quality hematite (Fe2O3) bodies. Synthetic magnetite (Fe3O4) nanoparticles (NPs), in recent years, have emerged as novel magnetic NPs with structurally distinct properties because of intensive research efforts by many researchers. They exhibited almost the same chemical and physical properties with naturally occurring Fe3O4, and they have been successfully adopted in removing trace metals from groundwater. For a better understanding of the development of suitable techniques for their application in contaminated groundwater, this paper emphasizes the synthetic methodology, surface modification, coating with porous materials/inorganic clays, functionalized composites, properties, and its ex situ groundwater remediation application. Magnetic separation is the most suitable and cost-effective method for the groundwater remediation of trace metals for both high and lower concentrations. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature